Vinegar

VINEGAR

Vinegar is an alcoholic liquid that has been allowed to sour. It is primarily used to flavor and

preserve foods and as an ingredient in salad dressings and marinades. Vinegar is also used as a

cleaning agent. The word is from the French vin (wine) and aigre (sour).

History

The use of vinegar to flavor food is centuries old. It has also been used as a medicine, a corrosive

agent, and as a preservative. In the Middle Ages, alchemists poured vinegar onto lead in order to

create lead acetate. Called "sugar of lead," it was added to sour cider until it became clear that

ingesting the sweetened cider proved deadly.

By the Renaissance era, vinegar-making was a lucrative business in France. Flavored with

pepper, clovers, roses, fennel, and raspberries, the country was producing close to 150 scented

and flavored vinegars. Production of vinegar was also burgeoning in Great Britain. It became so

profitable that a 1673 Act of Parliament established a tax on so-called vinegar-beer. In the early

days of the United States, the production of cider vinegar was a cornerstone of farm and

domestic economy, bringing three times the price of traditional hard cider.

The transformation of wine or fruit juice to vinegar is a chemical process in which ethyl alcohol

undergoes partial oxidation that results in the formation of acetaldehyde. In the third stage, the

acetaldehyde is converted into acetic acid. The chemical reaction is as follows: CH 3 CH 2

OH=2HCH 3 CHO=CH 3 COOH.

Historically, several processes have been employed to make vinegar. In the slow, or natural,

process, vats of cider are allowed to sit open at room temperature. During a period of several

months, the fruit juices ferment into alcohol and then oxidize into acetic acid.

The French Orleans process is also called the continuous method. Fruit juice is periodically

added to small batches of vinegar and stored in wooden barrels. As the fresh juice sours, it is

skimmed off the top.

Both the slow and continuous methods require several months to produce vinegar. In the modern

commercial production of vinegar, the generator method and the submerged fermentation

method are employed. These methods are based on the goal of infusing as much oxygen as

possible into the alcohol product.

Raw Materials

Vinegar is made from a variety of diluted alcohol products, the most common being wine, beer,

and rice. Balsamic vinegar is made from the Trebbiano and Lambrusco grapes of Italy's Emilia-

Romagna region. Some distilled vinegars are made from wood products such as beech.

Acetobacters are microscopic bacteria that live on oxygen bubbles. Whereas the fermentation of

grapes or hops to make wine or beer occurs in the absence of oxygen, the process of making

vinegars relies on its presence. In the natural processes, the acetobacters are allowed to grow

over time. In the vinegar factory, this process is induced by feeding acetozym nutrients into the

tanks of alcohol.

Mother of vinegar is the gooey film that appears on the surface of the alcohol product as it is

converted to vinegar. It is a natural carbohydrate called cellulose. This film holds the highest

concentration of acetobacters. It is skimmed off the top and added to subsequent batches of

alcohol to speed the formation of vinegar. Acetozym nutrients are manmade mother of vinegar in

a powdered form.

Herbs and fruits are often used to flavor vinegar. Commonly used herbs include tarragon, garlic,

and basil. Popular fruits include raspberries, cherries, and lemons.

Design

The design step of making vinegar is essentially a recipe. Depending on the type of vinegar to be

bottled at the production plant—wine vinegar, cider vinegar, or distilled vinegar—food scientists

in the test kitchens and laboratories create recipes for the various vinegars. Specifications include

the amount of mother of vinegar and/or acetozym nutrients added per gallon of alcohol product.

For flavored vinegars, ingredients such as herbs and fruits are macerated in vinegar for varying

periods to determine the best taste results.

The Manufacturing Process

The Orleans method

1. Wooden barrels are laid on their sides. Bungholes are drilled into the top side and plugged with

stoppers. Holes are also drilled into the ends of the barrels.

2. The alcohol is poured into the barrel via long-necked funnels inserted into the bungholes. Mother

of vinegar is added at this point. The barrel is filled to a level just below the holes on the ends.

Netting or screens are placed over the holes to prevent insects from getting into the barrels.

3. The filled barrels are allowed to sit for several months. The room temperature is kept at

approximately 85°F (29°C). Samples are taken periodically by inserting a spigot into the side

holes and drawing liquid off. When the alcohol has converted to vinegar, it is drawn off through

the spigot. About 15% of the liquid is left in the barrel to blend with the next batch.

The submerged fermentation method

1. The submerged fermentation method is commonly used in the production of wine vinegars.

Production plants are filled with large stainless steel tanks called acetators. The acetators are

fitted with centrifugal pumps in the bottom that pump air bubbles into the tank in much the same

way that an aquarium pump does.

2. As the pump stirs the alcohol, acetozym nutrients are piped into the tank. The nutrients spur the

growth of acetobacters on the oxygen bubbles. A heater in the tank keeps the temperature

between 80 and 100°F (26-38°C).

3. Within a matter of hours, the alcohol product has been converted into vinegar. The vinegar is

piped from the acetators to a plate-and-frame filtering machine. The stainless steel plates press

the alcohol through paper filters to remove any sediment, usually about 3% of the total product.

The sediment is flushed into a drain while the filtered vinegar moves to the dilution station.

The generator method

1. Distilled and industrial vinegars are often produced via the generator method. Tall oak vats are

filled with vinegar-moistened beechwood shavings, charcoal, or grape pulp. The alcohol product

is poured into the top of the vat and slowly drips down through the fillings.

2. Oxygen is allowed into the vats in two ways. One is through bungholes that have been punched

into the sides of the vats. The second is through the perforated bottoms of the vats. An air

compressor blows air through the holes.

3. When the alcohol product reaches the bottom of the vat, usually within in a span of several days

to several weeks, it has converted to vinegar. It is poured off from the bottom of the vat into

storage tanks. The vinegar produced in this method has a very high acetic acid content, often as

high as 14%, and must be diluted with water to bring its acetic acid content to a range of 5-6%.

4. To produce distilled vinegar, the diluted liquid is poured into a boiler and

The production of vinegar.

brought to its boiling point. A vapor rises from the liquid and is collected in a condenser. It then

cools and becomes liquid again. This liquid is then bottled as distilled vinegar.

Bascsamic vinegar

1. The production of balsamic vinegar most closely resembles the production of fine wine. In order

to bear the name balsamic, the vinegar must be made from the juices of the Trebbiano and

Lambrusco grapes. The juice is blended and boiled over a fire. It is then poured into barrels of

oak, chestnut, cherry, mulberry, and ash.

2. The juice is allowed to age, ferment, and condense for five years. At the beginning of each year,

the aging liquid is mixed with younger vinegars and placed in a series of smaller barrels. The

finished product absorbs aroma from the oak and color from the chestnut.

Quality Control

The growing of acetobacters, the bacteria that creates vinegar, requires vigilance. In the Orleans

Method, bungholes must be checked routinely to ensure that insects have not penetrated the

netting. In the generator method, great care is taken to keep the temperature inside the tanks in

the 80-100°F range (26-38°C). Workers routinely check the thermostats on the tanks. Because a

loss of electricity could kill the acetobacters within seconds, many vinegar plants have backup

systems to produce electrical power in the event of a blackout.

Byproducts/Waste

Vinegar production results in very little by-products or waste. In fact, the alcohol product is often

the by-product of other processes such as winemaking and baker's yeast.

Some sediment will result from the submerged fermentation method. This sediment is

biodegradable and can be flushed down a drain for disposal.

The Future

By the end of the twentieth century, grocery stores in the United States were posting $200

million in vinegar sales. White distilled vinegar garners the largest percentage of the market,

followed in order by cider, red wine, balsamic, and rice. Balsamic vinegar is the fastest growing

type. In addition to its continued popularity as a condiment, vinegar is also widely used as a

cleaning agent.

MAJOR ENZYME APPLICATIONS IN FOOD   INDUSTRY

I. Introduction

Enzymes are produced by all living cells as catalysts for specific chemical reactions. Not surprisingly enzymes are present in all foods at some time, and play an increasingly important role in food processing techniques. Enzymes, although not recognized as such, have played an essential part in some food processes, notably the making of cheese, leavened bread, wine and beer, for thousands of years (Dewdney, 1973).

II. Major Enzyme Applications in Food Industry

In food industry, enzyme has been used to produce and to increase the quality and the diversity of food. Some examples of products that use enzyme are cheese, yoghurt, bread syrup etc. Ancient traditional arts such as brewing, cheese making, meat tenderization with papaya leaves and condiment preparation (e.g., soy sauce and fish sauce) rely on proteolysis, albeit the methods were developed prior to our knowledge of enzymes. Early food processes involving proteolysis were normally the inadvertent consequence of endogenous or microbial enzyme activity in the foodstuff. Some major applications by types of enzymes are:

1. Rennet

The use of rennet in cheese manufacture was among the earliest applications of exogenous enzymes in food processing, dating back to approximately 6000 B C. In 1994, the total production of cheese was 8000 metric tons against a total demand of 9000 metric tons. The projected demand by 2000 A D is around 30,000 metric tons. The use of rennet, as an exogenous enzyme, in cheese manufacture is perhaps the largest single application of enzymes in food processing. In recent years, proteinases have found additional applications in dairy technology, for example in acceleration of cheese ripening, modification of functional properties and preparation of dietic products (IDF, 1990).

Picture 1.  Chymosin crystal structure (www.fst.rdg.ac.uk., 2002)

Animal rennet (bovine chymosin) is conventionally used as a milk-clotting agent in dairy industry for the manufacture of quality cheeses with good flavor and texture. Owing to an increase in demand for cheese production world wide – i.e. 4% per annum over the past 20 years, approximating 13.533 million tons (ref. 3) – coupled with reduced supply of calf rennet, has therefore led to a search for rennet substitutes, such as microbial rennet. At present, microbial rennet is used for one-third of all the cheese produced worldwide. Rennin acts on the milk protein in two stages, by enzymatic and by nonenzymatic action, resulting in coagulation of milk. In the enzymatic phase, the resultant milk becomes a gel due to the influence of calcium ions and the temperature used in the process (Bhoopathy, 1994). Many microorganisms are known to produce rennet-like proteinases which can substitute the calf rennet. Microorganisms like Rhizomucor pusillus, R. miehei, Endothia parasitica, Aspergillus oryzae, and Irpex lactis are used extensively for rennet production in cheese manufacture. Extensive research that has been

carried out so far on rennet substitutes has been reviewed by several authors (Green, M. L., 1977 Fox, P. F.1993; Farkye, N. Y., 1995).

Different strains of species of Mucor are often used for the production of microbial rennets. Whereas best yields of the milk-clotting protease from Rhizomucor pusillus are obtained from semisolid cultures containing 50% wheat bran, R. miehei and Endothia parasitica are well suited for submerged cultivation. Using the former, good yields of milk-clotting protease may be obtained in a medium containing 4% potato starch, 3% soybean meal, and 10% barley. During growth, lipase is secreted together with the protease. Therefore, the lipase activity has to be destroyed by reducing the pH, before the preparation can be used as cheese rennet.

1. Lactases

Lactose, the sugar found in milk and whey, and its corresponding hydrolase, lactase or b-galactosidase, have been extensively researched during the past decade (Mehaiya, 1987). This is because of the enzyme immobilization technique which has given new and interesting possibilities for the utilization of this sugar. Because of intestinal enzyme insufficiency, some individuals, and even a population, show lactose intolerance and difficulty in consuming milk and dairy products. Hence, low-lactose or lactose-free food aid programme is essential for lactose-intolerant people to prevent severe tissue dehydration, diarrhoea, and, at times, even death. Another advantage of lactase-treated milk is the increased sweetness of the resultant milk, thereby avoiding the requirement for addition of sugars in the manufacture of flavored milk drinks. Manufacturers of ice cream, yoghurt and frozen desserts use lactase to improve scoop and creaminess, sweetness, and digestibility, and to reduce sandiness due to crystallization of lactose in concentrated preparations. Cheese manufactured from hydrolyzed milk ripens more quickly than the cheese manufactured from normal milk.

Technologically, lactose crystallizes easily which sets limits to certain processes in the dairy industry, and the use of lactase to overcome this problem has not reached its fullest potential because of the associated high costs. Moreover, the main problem associated with discharging large quantities of cheese whey is that it pollutes the environment. But, the discharged whey could be exploited as an alternate cheap source of lactose for the production of lactic acid by fermentation. The whey permeate, which is a by-product in the manufacture of whey protein concentrates, by ultrafiltration could be fermented efficiently by Lactobacillus bulgaricus

(Mehaiya, 1987)

Lactose can be obtained from various sources like plants, animal organs, bacteria, yeasts (intracellular enzyme), or molds. Some of these sources are used for commercial enzyme preparations. Lactase preparations from A. niger, A. oryzae, and Kluyveromyces lactis are considered safe because these sources already have a history of safe use and have been subjected to numerous safety tests. The most investigated E. coli lactase is not used in food processing because of its cost and toxicity problems.

The properties of the enzyme depend on its source. Temperature and pH optima differ from source to source and with the type of particular commercial preparation. Immobilization of the enzymes, method of immobilization, and type of carrier can also influence these optima values.

In general, fungal lactase have pH optima in the acidic range 2.5–4.5, and yeast and bacterial lactases in the neutral region 6–7 and 6.5–7.5, respectively. The variation in pH optima of lactases makes them suitable for specific applications, for example fungal lactases are used for acid whey hydrolysis, while yeast and bacterial lactases are suitable for milk (pH 6.6) and sweet whey (pH 6.1) hydrolysis. Product inhibition, e.g. inhibition by galactose, is another property which also depends on the source of lactase. The enzyme from A. niger is more strongly inhibited by galactose than that from A. oryzae. This inhibition can be overcome by hydrolyzing lactose at low concentrations by using immobilized enzyme systems or by recovering the enzyme using ultrafiltration after batch hydrolysis. Lactases from Bacillus species are superior with respect to thermostability, pH operation range, product inhibition, and sensitivity against high-substrate concentration. Thermostable enzymes, able to retain their activity at 60°C or above for prolonged periods, have two distinct advantages viz. they give higher conversion rate or shorter residence time for a given conversion rate, and the process is less prone to microbial contamination due to higher operating temperature. Bacillus species have a pH optima of 6.8 and temperature optima of 65°C. Its high activity for skim milk and less inhibition by galactose has made it suitable for use as a production organism for lactase (Gekas, V. and Lopez-Levia, M., 1985).

The enzymatic hydrolysis of lactose can be achieved either by free enzymes, usually in batch fermentation process, or by immobilized enzymes or even by immobilized whole cells producing intracellular enzyme. Although numerous hydrolysis systems have been investigated, only few of them have been scaled up with success and even fewer have been applied at an industrial or semi-industrial level. Several acid hydrolysis systems have been developed to industry-scale level. Large-scale systems which use free enzyme process have been developed for processing of UHT-milk and processing of whey, using K. lactis lactase (Maxilact, Lactozyme).

Several commercial immobilized systems have been developed for commercial exploitation. Snamprogretti process of industrial-scale milk processing technology in Italy is one such working system. They make use of fibre-entrapped yeast lactase in a batch process, and the milk used is previously sterilized by UHT. For pilot plants, there are three other processes designed and developed to handle milk; (i) by Gist-Brocades, Rohm GmbH (Germany), and (ii) by Sumitomo, Japan. These are continuous processes with short residence times. Processing of whey UF-permeate is accomplished by the system developed by Corning Glass, Connecticut, Lehigh, Valio and Amerace corp. The process by Corning Glass is being applied at commercial scale in the bakers yeast production using hydrolyzed- whey (Gekas, V. and Lopez-Levia, M., 1985).

1. Catalases

Catalase is an enzyme that can be produced from bovine livers or microbial sources. It is used to change hydrogen peroxide to become water and oxygen molecules. This enzyme can be used in a limited amount in cheese production. Catalase is the enzyme that breaks down hydrogen peroxide to water and molecular oxygen. Catalase effectively removes the residual hydrogen peroxide, ensuring that the fabric is peroxide-free and mainly used in food industry and also in egg processing with other enzymes. Catalase is a common enzyme found in nearly all living

organisms which are exposed to oxygen, where it functions to catalyze the decomposition of hydrogen peroxide to water and oxygen (Chelikani P, Fita I, Loewen PC, 2004).

Glucose oxidase and catalase are often used together in selected foods for preservation. Superoxide dismutase is an antioxidant for foods and generates H2O2, but is more effective when catalase is present. Thermally induced generation of volatile sulphydryl groups is thought to be responsible for the cooked off-flavour in ultra high temperature (UHT) processed milk. Use of sulphydryl oxidase under aseptic conditions can eliminate this defect. The natural inhibitory mechanism in raw milk is due to the presence of low levels of lactoperoxidase (LP), which can be activated by the external addition of traces of H2O2 and thiocyanate. It has been reported that the potential of LP-system and its activation enhances the keeping quality of milk, (Muir, D. D., 1996)

1. Lipases

A lipase is a water –soluble enzyme that catalyzes the hydrolysis of ester bonds in water-insoluble, lipid substrates (Svendsen,  2000). Lipases (triacylglycerol acylhydrolases) are produced by microorganism in individual or together with esterase. Microorganisms that produce lipases are Pseudomonas aeruginosa, Serratia marcescens, Staphylocococcus aureus dan Bacillus subtilis. Lipase is used as biocatalyst to produce free fatty acid, glycerol and various esters, part of glycerides and fat that is modified or esterified from cheap substrate i.e. palm oil. Those products are extensively used in pharmacy, chemical and food industry.

Picture 4. Lipase crystal structure (Berman, H. M., J. Westbrook, Z. Feng, G. Gilliland, T. N. Bhat, H. Weissig, I. N. Shindyalov, and P. E. Bourne, 2000)

Various animal or microbial lipases gave pronounced cheese flavor, low bitterness and strong rancidity, while lipases in combination with proteinases and/or peptidases give good cheese flavor with low levels of bitterness. In a more balanced approach to the acceleration of cheese ripening using mixtures of proteinases and peptidases, attenuated starter cells or cell-free extracts (CFE) are being favored (Wilkinson, M. G., 1995)

1. Proteases

The proteolytic system of lactic acid bacteria is essential for their growth in milk, and contributes significantly to flavor development in fermented milk products. The proteolytic system is composed of proteinases which initially cleaves the milk protein to peptides; peptidases which cleave the peptides to small peptides and amino acids; and transport system responsible for cellular uptake of small peptides and amino acids. Lactic acid bacteria have a complex proteolytic system capable of converting milk casein to the free amino acids and peptides necessary for their growth. These proteinases include extracellular proteinases, endopeptidases, aminopeptidases, tripeptidases, and proline-specific peptidases, which are all serine proteases. Apart from lactic streptococcal proteinases, several other proteinases from nonlactostreptococcal origin have been reported. There are also serine type of proteinases, e.g. proteinases from Lactobacillus acidophillus, L. plantarum, L. delbrueckii sp. bulgaricus, L. lactis, and L. helveticus. Aminopeptidases are important for the development of flavor in fermented milk

products, since they are capable of releasing single amino acid residues from oligopeptides formed by extracellular proteinase activity (Law, J., And Haandrikman, A., 1997)

1. Amylases

They can be derived from bacteria and fungi. They play a major role in the food and beverages (baking), brewing, starch, sugar industries. Amylase is used to hydrolyze amilum into a product that is water soluble and has low molecular weight: glucose. This enzyme is used extensively in drink industry for example the production of High Fructose Syrup (HFS) or in textile industry. Amylases can be made from various microorganisms especially from Bacillus, Pseudomonas and Clostridium family. Potential bacteria that are recently used to produce amylases in industrial scale are Bacillus licheniformis and B.stearothermophillus. It is preferable to use B.stearothermophillus because it can produce enzyme that is thermo stable so that can reduce production cost.

Alpha amylases have significant effects on baked goods. If the content is low, this leads to low dextrin production and poor gas production. This in turn results in inferior quality bread with reduced size and poor crust color. To compensate for the deficiencies of the grain, it is necessary to add either sugar or alpha amylase. The addition of enzymes offers certain advantages over sugar. At a flour mill, it is possible to standardize the enzyme content of the flour so that a uniform commodity can be supplied. Furthermore, enzymes bring about a gradual formation of sugar, which matches the needs of the yeast. When the dough is placed in the oven, the steadily increasing temperature leads to an increase in the enzymes’ rate of reaction and more sugar is produced. Malt flour and malt extract can be used as enzyme supplements as malt is rich in alpha amylases. However, it is better to use a fungal alpha amylase.

The alpha-amylases degrade the damaged starch in wheat flour into small dextrins, thus allowing yeast to work continuously during dough fermentation, proofing and the early stage of baking. This results in improved bread volume and crumb texture. In addition, the small oligosaccharides and sugars such as glucose and maltose produced by these enzymes enhance the reactions for the browning of the crust and baked flavour. Cereal beta-amylases are perhaps best known in terms of the vital role they play in releasing easily fermentable sugars from cereal grain starch to fuel the production of alcohol by yeast in brewing. The extent to which they have been investigated is indeed largely due to their significance in this economically important industry. However, cereal beta-amylases are also, or could be, employed in many other aspects of the food industry and the analysis of starch, and they constitute valuable markers in cereal assessment and breeding studies (Ziegler, 1999).

The word "clarifier" is a bit of a misnomer for these materials we often use to help clean up the look of a beer or to reduce the amount of loose sediment in the bottom of our bottles. The clarification is the result of effectively settling the waste materials that would otherwise be causing cloudiness, possibly tainting the flavor of the beer, and making it difficult to cleanly pour the beer because of a thicker and looser sediment layer in the bottle.

The materials most commonly used for settling in beer are Irish Moss and/or Gelatin. Other agents are occasionally referenced but are generally not as effective or as neutral in their potential impact on the flavor of the beer. All clarifier/settlers work in the same way. They provide a surface which carries an ionic charge opposite that of the charge of the waste material. By coming into contact or in proximity to the waste, the waste is attracted to the surface of the agent and adsorbed to that surface. When enough waste has been adsorbed to make the settler particle heavy it falls out of suspension, carrying with it all of the waste that is stuck to it's surface.

In a light colored beer we consider this action to help in clarification, while in a dark colored beer we think of it as aiding in reduction of sediment. It is of course doing both in all beers, though we can not easily see through the dark beer. Does that mean it is not worth using a clarifier/settler in a dark beer? ABSOLUTELY NOT!!! It is always beneficial to settle out as much waste as you can. Less fermentation by-products will always mean a better tasting beer and a beer that has a thinner sediment layer which stays in place when poured... and in any beer you can see through, it will allow a crystal clarity that enhances the aesthetic tremendously.

Irish Moss and Gelatin should probably both be used in every beer. Irish Moss is used and removes waste that is separated from the wort during the boil cycle and keeps it from becoming a challenge later. Gelatin is added and removes waste created during the fermentation period. When the proper amounts of these two agents are used at the appropriate time, the finished beer will benefit greatly. Recommended methods of use may vary greatly depending on the source of information. Talk with us about it and we will explain the proper usage and the reasons behind our methods. REMEMBER, there always has to be a logical and sensible reason for doing anything in a particular way. That understanding is our goal for your brewing!

Clarifying agents in beer

Preservation by drying

Drying is a mass transfer process consisting of the removal of water or another solvent [1] by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be considered "dried", the final product must be solid, in the form of a continuous sheet (e.g. paper), long pieces (e.g. wood), particles (e.g. cereal grains or corn flakes) or powder (e.g. sand, salt, washing powder, milk powder). A source of heat, and an agent to remove the vapor produced by the process are necessary. In bioproducts like food, grains, and pharmaceuticals like vaccines, the solvent to be removed is almost invariably water.

In the most common case, a gas stream, e.g., air, applies the heat by convection and carries away the vapor as humidity. Other possibilities are vacuum drying, where heat is supplied by conduction or radiation (or microwaves) while the vapor thus produced is removed by the vacuum system. Another indirect technique is drum drying (used, for instance, for manufacturing potato flakes), where a heated surface is used to provide the energy and aspirators draw the vapor outside the room. In turn, the mechanical extraction of the solvent, e.g., water, by centrifugation, is not considered "drying".

Contents

 [hide]

1 Drying mechanism 2 Methods of drying 3 Applications of drying 4 References 5 Sources 6 External links

[edit] Drying mechanism

In some products having a relatively high initial moisture content, an initial linear reduction of the average product moisture content as a function of time may be observed for a limited time, often known as "constant drying rate period". Usually, in this period, it is surface moisture outside individual particles which is being removed. The drying rate during this period is dependent on the rate of heat transfer to the material being dried and therefore the maximum achievable drying rate is considered to be heat transfer limited. If drying is continued, the slope of the curve, the drying rate, becomes less steep (falling rate period) and eventually tends to the horizontal at very long times. The product moisture content is then constant at the "equilibrium moisture content", where it is in dynamic equilibrium with the dehydrating medium. In the falling rate period, water migration from the product interior to the surface is mostly by molecular diffusion, i,e. the water flux is proportional to the moisture content gradient. This means that water moves from zones with higher moisture content to zones with lower values, a phenomenon explained by the second law of thermodynamics. If water removal is considerable,

products usually undergo shrinkage and deformation, except in a well-designed freeze-drying process. The drying rate in the falling rate period is controlled by the rate of removal of moisture or solvent from the interior of the solid being dried and is referred to as being mass transfer limited.

[edit] Methods of drying

In a typical phase diagram, the boundary between gas and liquid runs from the triple point to the critical point. Regular drying is the green arrow, while supercritical drying is the red arrow and freeze drying is the blue.

Application of hot air (convective or direct drying). Air heating increases the driving force for heat transfer and accelerates drying. It also reduces air relative humidity, further increasing the driving force for drying. In the falling rate period, as moisture content falls, the solids heat up and the higher temperatures speed up diffusion of water from the interior of the solid to the surface. However, product quality considerations limit the applicable rise to air temperature. Excessively hot air can almost completely dehydrate the solid surface, so that its pores shrink and almost close, leading to crust formation or "case hardening", which is usually undesirable. For instance in wood (timber) drying, air is heated (which speeds up drying) though some steam is also added to it (which hinders drying rate to a certain extent) in order to avoid excessive surface dehydration and product deformation owing to high moisture gradients across timber thickness. Spray drying belongs in this category.

Indirect or contact drying (heating through a hot wall), as drum drying, vacuum drying. Again, higher wall temperatures will speed up drying but this is limited by product degradation or case-hardening. Drum drying belongs in this category.

Dielectric drying (radiofrequency or microwaves being absorbed inside the material) is the focus of intense research nowadays. It may be used to assist air drying or vacuum drying. Researchers have found that microwave finish drying speeds up the otherwise very low drying rate at the end of the classical drying methods.

Freeze drying or lyophilization is a drying method where the solvent is frozen prior to drying and is then sublimed, i.e., passed to the gas phase directly from the solid phase, below the melting point of the solvent. It is increasingly applied to dry foods, beyond its

already classical pharmaceutical or medical applications. It keeps biological properties of proteins, and retains vitamins and bioactive compounds. Pressure can be reduced by a high vacuum pump (though freeze drying at atmospheric pressure is possible in dry air). If using a vacuum pump, the vapor produced by sublimation is removed from the system by converting it into ice in a condenser, operating at very low temperatures, outside the freeze drying chamber.

Supercritical drying (superheated steam drying) involves steam drying of products containing water. This process is feasible because water in the product is boiled off, and joined with the drying medium, increasing its flow. It is usually employed in closed circuit and allows a proportion of latent heat to be recovered by recompression, a feature which is not possible with conventional air drying, for instance. The process has potential for use in foods if carried out at reduced pressure, to lower the boiling point.

Natural air drying takes place when materials are dried with unheated forced air, taking advantage of its natural drying potential. The process is slow and weather-dependent, so a wise strategy "fan off-fan on" must be devised considering the following conditions: Air temperature, relative humidity and moisture content and temperature of the material being dried. Grains are increasingly dried with this technique, and the total time (including fan off and on periods) may last from one week to various months, if a winter rest can be tolerated in cold areas.

Refractance Window drying : Refractance Window™ Technology is a novel drying system, developed by the owners of MCD Technologies, Inc. in Tacoma, Washington. It uses circulating water at atmospheric pressure as a means to carry thermal energy to material to be dehydrated. The products are spread on a transparent plastic conveyor belt and unused heat is recycled. Products on the moving belt dry in a few minutes, contrary to hot air tray or tunnel dryers which take several hours, or freeze dryers which dry overnight. Refractance Window™ drying is believed to have a major advantage over drum drying or spray drying, in that foods and pharmaceutical ingredients are exposed to much milder temperatures and final products maintain good sensory qualities, such as color and aroma. The technology is relatively inexpensive and the equipment is simple to operate and maintain.[2]

Infrared Zone Drying : Infrared Zone Drying™ (RZD™) Technology is an establish drying technology, patented by Columbia PhytoTechnology. It uses infrared energy applied to a thin film of product in a series of zones. This allows product to be maintained at a low enough temperature to avoid damage while in its liquid state. The end result is dehydration time less than 10 minutes and almost complete preservation of nutrients, flavor and color.[3] Unlike other gentle drying methods, such as freeze drying, it is a continuous high throughput process. Unlike low temperature spray drying RZD can dry liquids with suspended solids, such as purees, and also liquids that contain sugar without significant losses, such as fruit juice concentrates. The technology allows for independent control of the drying temperature and the infrared wavelength through the drying zones. A patent was filed that shows changing the wavelength effects the efficiency and drying rate. Targeting infrared wavelengths with high water absorption are critical to the dryer operation, output and product quality.[4]

[edit] Applications of drying

Drying of fish in Lofoten in the production of stockfish

Foods are dried to inhibit microbial development and quality decay. However, the extent of drying depends on product end-use. Cereals and oilseeds are dried after harvest to the moisture content that allows microbial stability during storage. Vegetables are blanched before drying to avoid rapid darkening, and drying is not only carried out to inhibit microbial growth, but also to avoid browning during storage. Concerning dried fruits, the reduction of moisture acts in combination with its acid and sugar contents to provide protection against microbial growth. Products such as milk powder must be dried to very low moisture contents in order to ensure flowability and avoid caking. This moisture is lower than that required to ensure inhibition to microbial development. Other products as crackers are dried beyond the microbial growth threshold to confer a crispy texture, which is liked by consumers.

Among Non-food products, those that require considerable drying are wood (as part of Timber processing), paper and washing powder. The first two, owing to their organic origins, may develop mold if insufficiently dried. Another benefit of drying is a reduction in volume and weight

Spray drying From Wikipedia, the free encyclopedia

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Laboratory-scale spray dryer.A=Solution or suspension to be dried in, B=Atomization gas in, 1= Drying gas in, 2=Heating of drying gas, 3=Spraying of solution or suspension, 4=Drying chamber, 5=Part between drying chamber and cyclone, 6=Cyclone, 7=Drying gas is taken away, 8=Collection vessel of product, arrows mean that this is co-current lab-spraydryer

Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals. A consistent particle size distribution is a reason for spray drying some industrial products such as catalysts. Air is the heated drying media; however, if the liquid is a flammable solvent such as ethanol or the product is oxygen-sensitive then nitrogen is used.[1]

All spray dryers use some type of atomizer or spray nozzle to disperse the liquid or slurry into a controlled drop size spray. The most common of these are rotary disks and single-fluid high pressure swirl nozzles. Alternatively, for some applications two-fluid or ultrasonic nozzles are used. Depending on the process needs, drop sizes from 10 to 500 µm can be achieved with the appropriate choices. The most common applications are in the 100 to 200 µm diameter range. The dry powder is often free-flowing.[2]

The most common spray dryers are called single effect as there is only one drying air on the top of the drying chamber (see n°4 on the scheme). In most cases the air is blown in co-current of the sprayed liquid. The powders obtained with such type of dryers are fine with a lot of dusts and a poor flowability. In order to reduce the dusts and increase the flowability of the powders, there is since over 20 years a new generation of spray dryers called multiple effect spray dryers. Instead of drying the liquid in one stage, the drying is done through two steps: one at the top (as per

single effect) and one or an integrated static bed at the bottom of the chamber. The integration of this fluidized bed allows, by fluidizing the powder inside a humid atmosphere, to agglomerate the fine particles and to obtain granules having commonly a medium particle size within a range of 100 to 300 µm. Because of this large particle size, these powders are free-flowing.

The fines generated by the first stage drying can be recycled in continuous flow either at the top of the chamber (around the sprayed liquid) or at the bottom inside the integrated fluidized bed. The drying of the powder can be finalized on an external vibrating fluidized bed.

The hot drying gas can be passed as a co-current or counter-current flow to the atomiser direction. The co-current flow enables the particles to have a lower residence time within the system and the particle separator (typically a cyclone device) operates more efficiently. The counter-current flow method enables a greater residence time of the particles in the chamber and usually is paired with a fluidized bed system.

Alternatives to spray dryers are:[3]

1. Freeze dryer : a more-expensive batch process for products that degrade in spray drying. Dry product is not free-flowing.

2. Drum dryer : a less-expensive continuous process for low-value products; creates flakes instead of free-flowing powder.

3. Pulse combustion dryer: A less-expensive continuous process that can handle higher viscosities and solids loading than a spray dryer, and that sometimes gives a freeze-dry quality powder that is free-flowing.

Contents

[hide]

1 Spray dryer 2 Micro-encapsulation 3 Spray drying applications 4 Nano spray dryer 5 References 6 Bibliography 7 Further reading 8 External links

[edit] Spray dryer

SDX spray drying nozzles.

Schematic illustration of spray drying process.

A spray dryer is a device used in spray drying. It takes a liquid stream and separates the solute or suspension as a solid and the solvent into a vapor. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapor stream and vaporised. Solids form as moisture quickly leaves the droplets. A nozzle is usually used to make the droplets as small as possible, maximising heat transfer and the rate of water vaporisation. Droplet sizes can range from 20 to 180 μm depending on the nozzle.[2] There are two main types of nozzles: high pressure single fluid nozzle (50 to 300 bars) and two-fluid nozzles: one fluid is the liquid to dry and the second is compressed gas (generally air at 1 to 7 bars).

Spray dryers can dry a product very quickly compared to other methods of drying. They also turn a solution, or slurry into a dried powder in a single step, which can be advantageous for profit maximization and process simplification.

[edit] Micro-encapsulation

Spray drying often is used as an encapsulation technique by the food and other industries. A substance to be encapsulated (the load) and an amphipathic carrier (usually some sort of modified starch) are homogenized as a suspension in water (the slurry). The slurry is then fed into a spray drier, usually a tower heated to temperatures well over the boiling point of water.

As the slurry enters the tower, it is atomized. Partly because of the high surface tension of water and partly because of the hydrophobic/hydrophilic interactions between the amphipathic carrier, the water, and the load, the atomized slurry forms micelles. The small size of the drops (averaging 100 micrometers in diameter) results in a relatively large surface area which dries quickly. As the water dries, the carrier forms a hardened shell around the load.[4]

Load loss is usually a function of molecular weight. That is, lighter molecules tend to boil off in larger quantities at the processing temperatures. Loss is minimized industrially by spraying into taller towers. A larger volume of air has a lower average humidity as the process proceeds. By the osmosis principle, water will be encouraged by its difference in fugacities in the vapor and liquid phases to leave the micelles and enter the air. Therefore, the same percentage of water can be dried out of the particles at lower temperatures if larger towers are used. Alternatively, the slurry can be sprayed into a partial vacuum. Since the boiling point of a solvent is the temperature at which the vapor pressure of the solvent is equal to the ambient pressure, reducing pressure in the tower has the effect of lowering the boiling point of the solvent.

The application of the spray drying encapsulation technique is to prepare "dehydrated" powders of substances which do not have any water to dehydrate. For example, instant drink mixes are spray dries of the various chemicals which make up the beverage. The technique was once used to remove water from food products; for instance, in the preparation of dehydrated milk. Because the milk was not being encapsulated and because spray drying causes thermal degradation, milk dehydration and similar processes have been replaced by other dehydration techniques. Skim milk powders are still widely produced using spray drying technology around the world, typically at high solids concentration for maximum drying efficiency. Thermal degradation of products can be overcome by using lower operating temperatures and larger chamber sizes for increased residence times.[5]

Recent research is now suggesting that the use of spray-drying techniques may be an alternative method for crystallization of amorphous powders during the drying process since the temperature effects on the amorphous powders may be significant depending on drying residence times.[6][7]

[edit] Spray drying applications

Food: milk powder, coffee, tea, eggs, cereal, spices, flavorings, starch and starch derivatives, vitamins, enzymes, colourings...

Pharmaceutical: antibiotics, medical ingredients, additives

Industrial: paint pigments, ceramic materials, catalyst supports, microalgae

[edit] Nano spray dryer

The nano spray dryer offers new possibilities in the field of spray drying. It allows to produce particles in the range of 300 nm to 5 μm with a narrow size distribution. High yields are produced up to 90% and the minimal sample amount is 1 mL.

FOOD ADDITIVES AND FLAVOUR ENHANCERS

Food additives-

Ascorbic Acid (Vitamin C) Papain,bulk Sodium AscorbateCalcium Citrate PHOSPHATES- all food grade Sodium Gluconate

Calcium Ascorbate Potassium Citrate Sorbic AcidCalcium Gluconate Potassium Gluconate Thaimine mononitrate

Citric Acid Potassium Sorbate Thiamine HCLL-Cysteine Pyroxidine Trisodium CitrateErythritol Riboflavin Trimagnesium Citrate

Glucono delta Lactone Rochelle Salt Vitamin B 2Glycerine Xanthan Gum

Monosodium Citrate Xylose Ascorbic Acid (Vitamin C) is used as a vitamin supplement in food and beverages, as a

dough conditioning agent as well as an antioxidant in canned and frozen prepared foods. Caffeine is a material with a strongly bitter taste. It is used in beverages and

pharmaceutical applications as a flavor and/or as a general nervous system stimulant. alcium Citrate is used as a calcium supplement, especially in acidic or slightly acidic

beverages and juices, tablets or other nutritional supplements. Citric Acid is the most widely used acid and pH control agent in the food industry. Citric

acid is characterized by a pleasant tart flavor easy solubility and stability. It is suitable for a wide range of food and industrial applications including beverages, confectionery canned foods and as a basic chemical.

Cream of Tartar (COT) is the acid potassium salt of L(+) tartaric acid. It functions to complex heavy metals and regulate pH, It is largely used in chemical leavening to release carbon dioxide as well as in metal coloring and galvanic tinning. It also functions as a taste regulator in sugar icing and in the controlled crystallization of toffees and fondants by the regulated inversion of sucrose.

Fumaric Acid is non-hygroscopic and guards against moisture pickup and caking. It is used in dry mix beverages, fruit juice drinks, gelatin desserts, pie fillings, refrigerated biscuit doughs, rye bread souring agents, jelling aids, wine, maraschino cherries and other products

Gluconic Acid 50% is an excellent chelating agent in alkaline solutions and is stable even in 1 5% caustic soda. It is mainly used for technical applications, e.g. for surface finishing of metals, in the textile industry for inhibiting precipitates on fibers and removing encrustations.

Malic Acid is the principal acid contained in apples and many other fruits and vegetables. Malic acid has a clean, mellow, smooth, lingering tart taste. Compared to citric acid, malic acid has a prolonged taste effect which can help mask the aftertaste of low calorie sweeteners.

Monosodium Citrate, an anhydrous acid salt, occupies an intermediate position between citric acid and the neutral trisodium citrate. It is used as a buffering agent in solutions, emulsions, beverage and food stuffs as well as an antioxidant. It is approved by the FDA CFR 181.29 as an indirect additive.

Na4EDTA (Tetrasodium Ethylenediaminetetraacetate) is the tetrasodium salt of ethylenediaminetetraacetic acid. Na4EDTA forms water-soluble coordination compounds with multivalent metal ions over a wide pH range.

Potassium Benzoate replaces sodium benzoate in applications where the preserving power of benzoic acid is required and a low sodium content is desirable.

Potassium Gluconate has applications similar to sodium gluconate and is also used as a potassium source in diabetic food and pharmaceuticals.

Potassium Sorbate is the very soluble salt of sorbic acid. It is used in many food products as a preservative with an effective pH range up to approximately 5.5 making it useful over a wider range than benzoates. Many dairy products with standards of identity allow the use of potassium sorbate as an optional ingredient, especially to check mold growth in certain kinds of cheese.

Rochelle Salt is the crystalline mixed sodium/potassium salt of tartaric acid used in medicine as a cathartic, in the preparation of mirrors, as a component of Fehling’s Solution, in metal finishing, in leavening agents, as a buffering agent and as a chelating agent.Sodium Benzoate, the sodium salt of benzoic acid, is most suitable for use as an antimicrobial agent in foods and beverages which are naturally in the pH range below 4.5 or can be brought there by addition of a suitable acidulant.

Sorbic Acid is used as a preservative effective against yeast and mold spoilage primarily up to pH 6.5 Sorbic acid is used in cheese making, pickles and other food applications.

Sorbitol is a multifunctional polyol (polyhydric alcohol) which can be used as a nutritive sugar substitute. Mainly used for its humectant properties in various food products, it also is used in sugarfree confections for crystallization control. Noncarinogenic and approximately 6O% as sweet as sugar Sorbitol is used in dietetic foods as a sugar substitute. Sorbitol is used for example in toothpaste, pet foods, surimi, chewing gum, bakery products and sugarfree candy.

Tartaric Acid is used as an acidulant in beverages, especially grape and lime flavored still beverages, as a leavening agent and a sequestrant. It also acts as a synergist with antioxidants to prevent rancidity in fats and oils.

Tripotassium Citrate shows a similar functionality to trisodium citrate, but provides easier solubility It is recommended in all diabetic food products which require a low sodium content. It finds pharmaceutical applications as a potassium and citrate source as well as in several technical applications.

Trisodium Citrate is a unique buffering salt for pH control in beverages, confectionery and numerous food products. Together with citric acid it ensures a precise pH-adjustment over a wide range. As a sequestrating agent it complexes cations like Ca, Mg and heavy metals, thus supporting the efficacy of anti oxidants.

Xanthan Gum is a stabilizer and thickener for aqueous systems with outstanding characteristics such as temperature, pH and salt stability and pseudoplastic flow behavior It is widely used in the food industry, but also finds numerous technical applications.

Flavour enhancers are food additives commonly added to food and designed to enhance the existing flavours of products. In western cultures, the 5th taste or umami went unrecognized for a long time. It was believed that flavour enhancers did not add any new taste of their own. It is

now understood that these substances activate taste receptors for umami, and thus add this taste to products.[1]

The commonly used flavour enhancers are:

Australian

Glutamic acid, monosodium glutamate, MSG, monopotassium glutamate, calcium diglutamate, monoammonium glutamate, magnesium diglutamate, disodium 5'-guanylate, disodium 5’-inosinate, disodium 5'-ribonucleotides, maltol, ethyl maltol, glycine, l-leucine.

European

Glutamic acid (an amino acid) and its salts: Glutamic acid, Monosodium glutamate, MSG, Monopotassium glutamate, Calcium, glutamate, Monoammonium glutamate, Magnesium diglutamate,

Guanylic acid (a ribonucleotide) and its salts: Guanylic acid, Disodium guanylate, sodium guanylate, Dipotassium guanylate, Calcium guanylate

Inosinic acid (a ribonucleotide) and its salts: Inosinic acid, Disodium inosinate, Dipotassium inosinate, Calcium inosinate,

Mixtures of guanylate and inosinate: Calcium 5'-ribonucleotides, Disodium 5'-ribonucleotides

Maltol and ethyl maltol: Maltol, Ethyl maltol, Amino acids and their salts: Glycine and its sodium salt, L-Leucine

Flavor enhancer

Glutamic acid, being a constituent of protein, is present in every food that contains protein, but it can only be tasted when it is present in an unbound form. Significant amount of free glutamic acid are present in a wide variety of foods, including cheese and soy sauce, and is responsible for umami, one of the five basic tastes of the human sense of taste. Glutamic acid is often used as a food additive and flavour enhancer in the form of its sodium salt monosodium glutamate (MSG).

Name Comments

Glutamic acid

Natural amino acid (building block of protein). Commercially prepared from molasses by bacterial fermentation. Also prepared from vegetable protein, such as gluten, or soy protein. Glutamic acid and glutamates are present in all proteins. Free glutamates are present in high concentrations in ripened cheese, breast milk, tomatoes and sardines. Flavour enhancer, salt substitute used in sausages, seasoning, savoury snacks - many savoury foods. An amino acid present in many animal and vegetable proteins, derived commercially from bacteria; might cause similar problems as MSG (621), young children should avoid it. It could kill nerve cells, resulting in diseases such as Huntington's, Alzheimer's and Parkinson's.

Monosodium L-glutamate (MSG)

Sodium salt from glutamic acid (E620), a natural amino acid (building block of protein). Commercially prepared from molasses by bacterial fermentation. Added to

any savoury processed protein food.  In cigarettes and animal food.  In over 10,000 foods in USA.  Flavour enhancer derived from the fermentation of molasses, salt substitute; adverse effects appear in some asthmatic people, should not be permitted in foods for infants and young children as it could damage the nervous system. Typical products are canned vegetables, canned tuna, dressings, many frozen foods. To be avoided. It could kill nerve cells, resulting in diseases such as Huntington's, Alzheimer's and Parkinson's. Pregnant women, children, hypoglycaemic, elderly and those with heart disease are at risk from reactions.

Monopotassium L-glutamate

Potassium salt from glutamic acid (E620), a natural amino acid (building block of protein). Commercially prepared from molasses by bacterial fermentation. Also prepared from vegetable protein, such as gluten, or soy protein. Less used and not as salty, low sodium salt substitute. Can cause nausea, vomiting, diarrhoea, abdominal cramps; typical products are low sodium salt substitutes. Not for babies under 12 months old or those people with impaired kidneys.  See 621.

Calcium di-L-glutamate

g block of protein). Commercially prepared from molasses by bacterial fermentation. Also prepared from vegetable protein, such as gluten, or soy protein. Salt substitute, no known adverse effects, but possible problems for asthmatics and aspirin sensitive people. See 621.

Monoammonium L-glutamateg block of protein). Commercially prepared from molasses by bacterial fermentation. Also prepared from vegetable protein, such as gluten, or soy protein. Salt substitute, flavour enhancer. No known adverse effects.

Magnesium di-L-glutamate

g block of protein). Commercially prepared from molasses by bacterial fermentation. Also prepared from vegetable protein, such as gluten, or soy protein. Salt substitute, flavour enhancer. Hardly used, only in low sodium meat products. No known adverse effects.

Guanylic acid

Not listed for use in Australia. Guanylic acid is a natural acid, which is part of RNA, one of the genetic carrier molecules in the cell. It is thus part of all cells in all living organisms. Commercially prepared from yeast extract or sardines. Asthmatic people should avoid guanylic acid and guanylates. As guanylates are metabolised to purines, they should be avoided by people suffering from gout.

Disodium guanylate

Flavour enhancer. Isolated from sardines or yeast extract; not permitted in foods for infants and young children. Persons with gout, hyperactivity, asthmatics and aspirin sensitive's should avoid it.    It is found in instant noodles, potato chips and snacks, savoury rice, tinned vegetables, cured meats, packet soup.

Dipotassium guanylate, 5'-

Flavour enhancer. Guanylic acid and guanylates do not have the specific umami taste but strongly enhance many other flavours, thereby reducing the amounts of salt needed in a product. Asthmatic people should avoid guanylic acid and guanylates. As guanylates are metabolised to purines, they should be avoided by people suffering from gout. However, the concentrations used are generally so low that no effects are to be expected. Guanlyic acic and guanylates are generally produced from yeasts, but partly also from fish. They may thus not suitable for vegans and vegetarians.

Calcium guanylate Calcium salt of guanylic acid (E626), a natural acid, which is part of RNA, one of the genetic carrier molecules in the cell. It is thus part of all cells in all living organisms. Commercially prepared from yeast extract or sardines.Flavour enhancer. Guanylic acid and guanylates do not have the specific umami taste but strongly enhance many other flavours, thereby reducing the amounts of salt needed in a product. Used in many products, mainly in low-salt/sodium products. Acceptable

daily intake (ADI): None determined. Guanylates may not be used in products intended for children under 12 weeks. Asthmatic people should avoid guanylic acid and guanylates. As guanylates are metabolised to purines, they should be avoided by people suffering from gout.

Inosinic acid

A natural acid, that is mainly present in animals. Commercially prepared from meat or fish (sardines). May also be produced by bacterial fermentation of sugars. Used by athletes to supposedly increase the oxygen capacity of there blood. Used in many products. Acceptable daily intake (ADI): None determined. Inosinates may not be used in products intended for children under 12 weeks. Asthmatic people should avoid inosinates. As inosinates are metabolised to purines, they should be avoided by people suffering from gout. Inosinates are generally produced from meat, but partly also from fish. They are thus not suitable for vegans and vegetarians, and in most cases not suitable for Jews, Muslims and Hindus, depending on the origin of the product. Only the producer can provide information on the origin.

Disodium inosinate

May be prepared from meat or sardines; not permitted in foods for infants and young children. Gout sufferers avoid.  It is found in instant noodles, potato chips and snacks, savoury rice, tinned vegetables, cured meats, packet soup.  Asthmatic people should avoid inosinates. As inosinates are metabolised to purines, they should be avoided by people suffering from gout. Frequently contains MSG(621).

Dipotassium inosinate

Potassium salt of inosinic acid (E630), a natural acid, that is mainly present in animals. Commercially prepared from meat or fish (sardines). May also be produced by bacterial fermentation of sugars. Flavour enhancer. Inosinic acid and inosinates do not have the specific umami taste but strongly enhance many other flavours, thereby reducing the amounts of salt or other flavour enhancers needed in a product. Used in many products. Mainly used in low sodium/salt products. Acceptable daily intake (ADI): None determined. Inosinates may not be used in products intended for children under 12 weeks. Asthmatic people should avoid inosinates. As inosinates are metabolised to purines, they should be avoided by people suffering from gout. However, the concentrations used are generally so low that no effects are to be expected. Inosinates are generally produced from meat, but partly also from fish. They are thus not suitable for vegans and vegetarians, and in most cases not suitable for Jews, Muslims and Hindus, depending on the origin of the product. Only the producer can provide information on the origin.

Calcium inosinate

Calcium salt of inosinic acid (E630), a natural acid, that is mainly present in animals. Commercially prepared from meat or fish (sardines). May also be produced by bacterial fermentation of sugars. Flavour enhancer. Inosinic acid and inosinates do not have the specific umami taste but strongly enhance many other flavours, thereby reducing the amounts of salt or other flavour enhancers needed in a product. Used in many products. Mainly used in low sodium/salt products. Acceptable daily intake (ADI): None determined. Inosinates may not be used in products intended for children under 12 weeks. Asthmatic people should avoid inosinates. As inosinates are metabolised to purines, they should be avoided by people suffering from gout. However, the concentrations used are generally so low that no effects are to be expected.

Calcium 5'-ribonucleotides Mixture of calcium salts of guanylic (E626) and inosinic acid (E630). Flavour enhancer. Guanylates and inosinates do not have the specific umami taste but strongly enhance many other flavours, thereby reducing the amounts of salt or other flavour enhancers needed in a product. Used in many products. Mainly used in low sodium/salt products. Acceptable daily intake (ADI): None determined. Guanylates

and inosinates may not be used in products intended for children under 12 weeks. Asthmatic people should avoid guanylates and inosinates. As guanylates and inosinates are metabolised to purines, they should be avoided by people suffering from gout. However, the concentrations used are generally so low that no effects are to be expected.

Disodium 5'-ribonucleotide

Made from 627 and 631.  Check imported foods. May be associated with itchy skin rashes up to 30 hours after ingestion; rashes may vary from mild to dramatic; the reaction is dose-related and cumulative, some individuals are more sensitive than others; typical foods include flavoured chips, instant noodles and party pies. Avoid it, especially gout sufferers, asthmatics and aspirin sensitive people.

Sodium 5'-ribonucleotide

Mixture of sodium salts of guanylic (E626) and inosinic acid (E630).  Check imported foods. May be associated with itchy skin rashes up to 30 hours after ingestion; rashes may vary from mild to dramatic; the reaction is dose-related and cumulative, some individuals are more sensitive than others; typical foods include flavoured chips, instant noodles and party pies. Avoid it, especially gout sufferers, asthmatics and aspirin sensitive people. Banned in Australia.

Maltol

Derived from the bark of larch trees, pine needles, chicory wood, oils and roasted malt; it may be produced synthetically. Artificial sweetener, flavour enhancer used in baked goods to give a 'fresh baked' taste and smell in bread and cakes, chocolate substitute, soft and fizzy drinks, ice cream, jam. In large quantities it can help aluminium pass into the brain to cause Alzheimer's disease. Sometimes lactose (from cow's milk) is used. It should thus be avoided by vegans. It does not contain lactose and can be used by lactose-intolerant people. Acceptable daily intake (ADI): Up to 2 mg/kg bodyweight.  Some countries ban it for babies and young children.

Ethyl maltol

Derived from maltol chemically. Needs more testing. Base for essences, synthetic artificial flavour and flavour enhancer. Sometimes lactose (from cow's milk) is used. It should thus be avoided by vegans. It does not contain lactose and can be used by lactose-intolerant people. Some countries ban it for babies and young children.  See 636. Acceptable daily intake (ADI): Up to 2 mg/kg bodyweigh

Glycine (and its sodium salts),

glycol, amino acetic acid

Flavour modifier. Glycine is a natural amino acid, a building block of protein. Mainly produced from gelatin, partly synthetic. It is a nutrient, mainly for yeast in bread. Also used as a bread enhancer. Genetically coded amino acid used in dietary supplements. Can be mildly toxic if ingested. Glycine is produced mainly from gelatin, which is derived from animal bones. It is therefore not suitable for vegans, vegetarians and, as long as the origin is not known, not for Jews, Muslims and Hindus. Only the producer can provide the origin of the product.

Nutrient

All meats, poultry, fish, eggs, dairy products, and kombu are excellent sources of glutamic acid. Some protein-rich plant foods also serve as sources. Thirty to 35% of the protein in wheat is glutamic acid. Ninety-five percent of the dietary glutamate is metabolized by intestinal cells in a first pass.[19]

1) Monosodium glutamate, also known as sodium glutamate or MSG, is the sodium salt of glutamic acid, one of the most abundant naturally occurring non-essential amino acids.[1] It has been classified by the U.S. Food and Drug Administration as generally recognized as safe (GRAS) and by the European Union as a food additive. MSG has the HS code

29224220 and the E number E621.[2] The glutamate of MSG confers the same umami taste of glutamate from other foods, being chemically identical.[3] Industrial food manufacturers market and use MSG as a flavor enhancer because it balances, blends and rounds the total perception of other tastes.[4]

2) Calcium diglutamate, sometimes abbreviated CDG and also called calcium glutamate, is a compound with formula Ca(C5H8NO4)2. It is a calcium acid salt of glutamic acid. CDG is a flavor enhancer (E number E623) — it is the calcium analog of monosodium glutamate (MSG). Because the glutamate is the actual flavor-enahancer, DCG has the same flavor-enhancing properties as MSG, but without the increased sodium content.[1] As a soluble source of calcium ions, this chemical is also used as a first-aid treatment for exposure to hydrofluoric acid.[2]

3) Maltol is a naturally occurring organic compound that is used primarily as a flavor enhancer. It is found in the bark of larch tree, in pine needles, and in roasted malt (from which it gets its name). It is a white crystalline powder that is soluble in hot water, chloroform, and other polar solvents. Because it has the odor of cotton candy and caramel, maltol is used to impart a sweet aroma to fragrances. Maltol's sweetness adds to the odor of freshly baked bread, and is used as a flavor enhancer (E number E636) in breads and cakes.

4) Maltol, like related 3-hydroxy-4-pyrones such as kojic acid, binds to hard metal centers such as Fe3+, Ga3+, Al3+, and VO2+.[1] Related to this property, maltol has been reported to greatly increase aluminum uptake in the body [2] and to increase the oral bioavailability of gallium [3] and iron. [4]

5) Glycine (abbreviated as Gly or G)[4] is an organic compound with the formula NH2CH2COOH. Having a hydrogen substituent as its side-chain, glycine is the smallest of the 20 amino acids commonly found in proteins. Its codons are GGU, GGC, GGA, GGG cf. the genetic code.

6) Glycine is a colourless, sweet-tasting crystalline solid. It is unique among the proteinogenic amino acids in that it is not chiral. It can fit into hydrophilic or hydrophobic environments, due to its two hydrogen atom side chain. Other markets for USP grade glycine include its use an additive in pet food and animal feed. For humans, glycine is sold as a sweetener/taste enhancer. Food supplements and protein drinks contain glycine. Certain drug formulations include glycine to improve gastric absorption of the drug.

7) Thaumatin is a low-calorie sweetener and flavour modifier. The substance, a natural protein, is often used primarily for its flavour-modifying properties and not exclusively as a sweetener.[1] The thaumatins were first found as a mixture of proteins isolated from the katemfe fruit (Thaumatococcus daniellii Bennett) of west Africa. Some of the proteins in the thaumatin family are natural sweeteners roughly 2000 times more potent than sugar. Although very sweet, thaumatin's taste is markedly different from sugar's. The sweetness of thaumatin builds very slowly. Perception lasts a long time, leaving a liquorice-like aftertaste at high usage levels. Thaumatin is highly water soluble, stable to heating, and stable under acidic conditions.

Applications of proteases in the food industry

Certain proteases have been used in food processing for centuries and any record of the discovery of their activity has been lost in the mists of time. Rennet (mainly chymosin), obtained from the fourth stomach (abomasum) of unweaned calves has been used traditionally in the production of cheese. Similarly, papain from the leaves and unripe fruit of the pawpaw (Carica papaya) has been used to tenderise meats. These ancient discoveries have led to the development of various food applications for a wide range of available proteases from many sources, usually microbial. Proteases may be used at various pH values, and they may be highly specific in their choice of cleavable peptide links or quite non-specific. Proteolysis generally increases the solubility of proteins at their isoelectric points.

The action of rennet in cheese making is an example of the hydrolysis of a specific peptide linkage, between phenylalanine and methionine residues (-Phe105-Met106-) in the k-casein protein present in milk (see reaction scheme [1.3]). The k-casein acts by stabilising the colloidal nature of the milk, its hydrophobic N-terminal region associating with the lipophilic regions of the otherwise insoluble a- and b-casein molecules, whilst its negatively charged C-terminal region associates with the water and prevents the casein micelles from growing too large. Hydrolysis of the labile peptide linkage between these two domains, resulting in the release of a hydrophilic glycosylated and phosphorylated oligopeptide (caseino macropeptide) and the hydrophobic para-k-casein, removes this protective effect, allowing coagulation of the milk to form curds, which are then compressed and turned into cheese (Figure 4.1). The coagulation process depends upon the presence of Ca2+ and is very temperature dependent (Q10 = 11) and so can be controlled easily. Calf rennet, consisting of mainly chymosin with a small but variable proportion of pepsin, is a relatively expensive enzyme and various attempts have been made to find cheaper alternatives from microbial sources These have ultimately proved to be successful and microbial rennets are used for about 70% of US cheese and 33% of cheese production world-wide.

Figure 4.1. Outline method for the preparation of cheese.

The major problem that had to be overcome in the development of the microbial rennets was temperature lability. Chymosin is a relatively unstable enzyme and once it has done its major job, little activity remains. However, the enzyme from Mucor miehei retains activity during the maturation stages of cheese-making and produces bitter off-flavours. Treatment of the enzyme with oxidising agents (e.g. H2O2, peracids), which convert methionine residues to their sulfoxides, reduces its thermostability by about 10�C and renders it more comparable with calf rennet. This is a rare example of enzyme technology being used to destabilise an enzyme Attempts have been made to clone chymosin into Escherichia coli and Saccharomyces cerevisiae but, so far, the enzyme has been secreted in an active form only from the latter.

The development of unwanted bitterness in ripening cheese is an example of the role of proteases in flavour production in foodstuffs. The action of endogenous proteases in meat after slaughter is complex but 'hanging' meat allows flavour to develop, in addition to tenderising it. It has been found that peptides with terminal acidic amino acid residues give meaty, appetising flavours akin to that of monosodium glutamate. Non-terminal hydrophobic amino acid residues in medium-sized oligopeptides give bitter flavours, the bitterness being less intense with smaller peptides

and disappearing altogether with larger peptides. Application of this knowledge allows the tailoring of the flavour of protein hydrolysates. The presence of proteases during the ripening of cheeses is not totally undesirable and a protease from Bacillus amyloliquefaciens may be used to promote flavour production in cheddar cheese. Lipases from Mucor miehei or Aspergillus niger are sometimes used to give stronger flavours in Italian cheeses by a modest lipolysis, increasing the amount of free butyric acid. They are added to the milk (30 U l-1) before the addition of the rennet.

When proteases are used to depolymerise proteins, usually non-specifically, the extent of hydrolysis (degree of hydrolysis) is described in DH units where:

             (4.1)

Commercially, using enzymes such as subtilisin, DH values of up to 30 are produced using protein preparations of 8-12% (w/w). The enzymes are formulated so that the value of the enzyme : substrate ratio used is 2-4% (w/w). At the high pH needed for effective use of subtilisin, protons are released during the proteolysis and must be neutralised:

subtilisin (pH 8.5)                                        H2N-aa-aa-aa-aa-aa-COO- H2N-aa-aa-aa-COO- + H2N-aa-aa-COO- + H+         [4.1]

where aa is an amino acid residue.

Correctly applied proteolysis of inexpensive materials such as soya protein can increase the range and value of their usage, as indeed occurs naturally in the production of soy sauce. Partial hydrolysis of soya protein, to around 3.5 DH greatly increases its 'whipping expansion', further hydrolysis, to around 6 DH improves its emulsifying capacity. If their flavours are correct, soya protein hydrolysates may be added to cured meats. Hydrolysed proteins may develop properties that contribute to the elusive, but valuable, phenomenon of 'mouth feel' in soft drinks.

Proteases are used to recover protein from parts of animals (and fish) would otherwise go to waste after butchering. About 5% of the meat can be removed mechanically from bone. To recover this, bones are mashed incubated at 60�C with neutral or alkaline proteases for up to 4 h. The meat slurry produced is used in canned meats and soups.

Large quantities of blood are available but, except in products such black puddings, they are not generally acceptable in foodstuffs because of their colour. The protein is of a high quality nutritionally and is de-haemed using subtilisin. Red cells are collected and haemolysed in water. Subtilisin is added and hydrolysis is allowed to proceed batchwise, with neutralisation of the released protons, to around 18 DH, when the hydrophobic haem molecules precipitate. Excessive degradation is avoided to prevent the formation of bitter peptides. The enzyme is inactivated by a brief heat treatment at 85�C and the product is centrifuged; no residual activity allowed into meat products. The haem-containing precipitate is recycled and the light-brown supernatant is

processed through activated carbon beads to remove any residual haem. The purified hydrolysate, obtained in 60% yield, may be spray-dried and is used in cured meats, sausages and luncheon meats.

Meat tenderisation by the endogenous proteases in the muscle after slaughter is a complex process which varies with the nutritional, physiological and even psychological (i.e. frightened or not) state of the animal at the time of slaughter. Meat of older animals remains tough but can be tenderised by injecting inactive papain into the jugular vein of the live animals shortly before slaughter. Injection of the active enzyme would rapidly kill the animal in an unacceptably painful manner so the inactive oxidised disulfide form of the enzyme is used. On slaughter, the resultant reducing conditions cause free thiols to accumulate in the muscle, activating the papain and so tenderising the meat. This is a very effective process as only 2 - 5 ppm of the inactive enzyme needs to be injected. Recently, however, it has found disfavour as it destroys the animals heart, liver and kidneys that otherwise could be sold and, being reasonably heat stable, its action is difficult to control and persists into the cooking process.

Proteases are also used in the baking industry. Where appropriate, dough may be prepared more quickly if its gluten is partially hydrolysed. A heat-labile fungal protease is used so that it is inactivated early in the subsequent baking. Weak-gluten flour is required for biscuits in order that the dough can be spread thinly and retain decorative impressions. In the past this has been obtained from European domestic wheat but this is being replaced by high-gluten varieties of wheat. The gluten in the flour derived from these must be extensively degraded if such flour is to be used efficiently for making biscuits or for preventing shrinkage of commercial pie pastry away from their aluminium dishes.