“UHT (ULTRA-HIGH TEMPERATURE) TECNOLOGY FOR PROCESSING OF LONG LIFE MILK A PROSPECT IN NEPAL.”

© Mr Ashok Acharya, for the partial fulfillment of Undergraduate In Industrial Engineering, Tribhuwan University, Institute Of Engineering (IOE)

Thapathali Campus,Thapathali,Kathmandu,Nepal

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Ashok Acharya

For the Partial Fulfillment of Undergraduate In Industrial Engineering

Tribhuwan University.

Institute Of Engineering (IOE), Thapathali Campus,Thapathali,Kathmandu,Nepal.

Comments me at: [email protected], [email protected].

http://www.tcampus.com

Web source: ^^www.pdfsearchengine.com/UHT Dairy Technology

seminarpaperashokacharya/.pdf.

April 2010

mailto:[email protected]

http://www.tcampus.com/



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“UHT (ULTRA-HIGH TEMPERATURE) TECNOLOGY FOR PROCESSING OF LONG LIFE MILK A PROSPECT IN NEPAL.”

Ashok Acharya For the partial fulfillment of Undergraduate in Industrial Engineering Institute of Engineering,Thapathali Campus,Kathmandu,Nepal

Abstract

Nepal is a geographically diversified country. Major percentages of the people are Farmers among them most of them consume locally produced milk from the cows that they raise in the farm. Most of the farmer people are involved in the milk production. As the geographical condition of Nepal is diversified there is difference in the climatic condition of Nepal in the different regions; Hills and high mountain-86%, Terai plain-14%( Shrestha, 2007) of total area of Nepal. Among the three regions with elevation ranging from 60 m to 8848m Mt.Everest (Shrestha, 2007). There is vast Climatic diversity-diversity in habitat, plants and animals, Seasonal variation-rains in monsoon, snowfall in winter, high temperature in summer, one season-different climate in different landscape of Nepal. These diversification gives the country different kind of Mammalian Animals, Among them there are different milking Animals in Nepal as Cow, Buffalo, Sheep, Yak, Goat etc. Cow and Buffalo Milk is quite popular in the Nation. The milk cannot be kept for more than 4 to 5 hours (Bylund, 1986) at ambient temperature immediately after milking. Cooling equipments are not available in many parts of the Nepal and if available, which are not affordable to these poor people. Milk preservation prior to distribution and sale is major problem in Nepal. The people are suffering a lot of problem in Animal husbandry for Milk products and the produced milk they even cannot consume all of them and not even they can supply to different place within few hours. In case of the Urban Areas, people use industrially produced milk from different private and government dairies. Most of the dairy product does not last for more than a day if not stored in Refrigerator. So no such milk products are available which remains fresh without refrigerating after few hours. The milk products that are found in Nepal could not be used more than a few days and some are exported from other county like China and India, As the milk products are pasteurized as major dairy companies in Nepal are producing pasteurized milk which last for few days only. If new and latest technology such as UHT (Ultra High Temperature) could be used in Nepal then the milk products don‟t need any refrigeration and could be stored for more



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than 3 months but up to 10 months and there would be no burden to export from the other country. So, it is necessary to develop a new sciencitific and efficient method to overcome such problems. If low cost and highly effective technology for preservation of milk can be implemented in country, it can be beneficial to the people as an opportunity. UHT treatment for milk, dairy material means the application of heat to a continuously flowing milk or liquid dairy material using such high temperatures for such time that renders the product commercially sterile at the time of processing. When the UHT treatment is combined with aseptic packaging, it results in a commercially sterile dairy product that is sufficient to ensure that the product remains microbiologically stable after incubating, thereby reducing the spoiling of nutrients and has excellent keeping qualities and stored for long period of time at ambient temperature. Aseptic packaging machines are very expensive and UHT milk depends entirely on it. There is a need to reduce its cost so that UHT processing and packaging machine can be approachable to rural poor farmers in Nepal.

Key Words: UHT, Milk processing, Sterilization, Rural, sterilization.

Introduction

Milk is an ancient as mankind itself, as it is the substance created to feed the mammalian

infant. All species of mammals, from man to whales, produce milk for this purpose. The

first food man takes on birth, is a „treasure trove‟ of more than 200 ingredients (Kishor,

2007), many with many nutritional and functional property. The milk giving animals mostly

includes cows (genus Bos), buffaloes, sheep, goats, and camels, all of which are still used

in various parts of the world for the production of milk for human consumption. Milk also

acts as raw materials for producing variety of products using it.

At present there are huge binaries of the UHT products are used across the world, The

UHT milk as a percentage of total consumption at present in different countries of the

world is shown in the next page:



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Source:www.wikipedia.org/UHT milk.htm

Chart I: Showing the UHT milk as a percentage of total consumption at present in different

countries of the world.

UHT milk has seen large success in much of Europe, and where across the continent as a

whole 7 out of 10 Europeans (www.wikipedia.org/UHT.htm) drink it regularly. In fact, in a

hot country like Spain, UHT is preferred due to high costs of refrigerated transportation

and "inefficient cool cabinets." Europe's largest manufacturer, Parmalat, had $6 billion of

sales in 1999(www.wikipedia.org/UHT.htm). However, these figures conceal wide

variations as in most European countries High Temperature/Short Time (HTST)

pasteurized milk is more popular.

Majority of the people are farmer; the total production of Milk in Nepal is high and it

would increase more if the promotion program to the farmer from the government and

private side made time to time. But Lack of Appropriate technology all the produced Milk

cannot be utilized efficiently. Dairy sub-sector shares more than 60 % of livestock sector

contribution to GDP(Source:www.pdf-search engine/). Annual production of milk is 1.35

million metric ton. Buffaloes contribute more than 2/3 of the volume. 13 % of total cattle

population (0.9 million) & 26 % buffaloes (1.19 million) are milking. (Source:www.pdf-

search engine/). The huge corporation of Nepal DDC (Dairy Development Corporation)

collects annual over 60 million liters of milk from more than 75 thousand milk producers

through 888 milk cooperatives spread out in 33 district (http://www.dairydev.com.np) and

also there are private dairies they contribute some millions liters per year, out of which

some percentage is only consumed and rest is send for the industrial processing. Most of

the economically poor Nepalese communities, who are staying in rural areas, are involved

in milk production where

http://www.wikipedia.org/UHT%20milk.htm

http://en.wikipedia.org/wiki/Europe

http://en.wikipedia.org/wiki/Parmalat

http://en.wikipedia.org/wiki/Flash_pasteurization



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the refrigerating system is not found and even they cannot economically offered personally for extending the long life of the milk. The milk produced in these rural areas has the high demand in the urban areas like Kathmandu, Biratnagar, Itahari, Birtamod, Hetauda, Pokhara,etc of Nepal. Milk preservation, distribution and sale with the appropriate price are a major problem in rural region of Nepal. So, new scientific and efficient method is required to cope with such problems. Presently more than 50 districts dairy co-operatives societies have been opened up in Nepal, where more than 40% farmers among the total population are involved according to the data of DDC. If appropriate and low cost type of technology for the preservation of milk can be implemented that would be boom for the rural areas of farmer and their family. With the advent of advent of Ultra High Temperature (UHT) treatment of milk has added new features to marketing of liquid milk in urban centers as well as remote areas of Country. There are a lot of advantages for the producer, retailer and consumer if a milk Product does not require refrigeration power and can be stored for long periods without spoiling the product. For example for the producers can reach geographically wider markets, simplify production planning by reducing the changes and defects to the products, also make deliveries easier by using fewer and cheaper distribution Vehicles and can eliminate return of the products that are unsold. Handling of the products becomes easier for the retailer, as compare to the expensive refrigerated display space products and the important thing is that the milk can bought anywhere, at anytime and even stock planning can be simplified. “Ultra-high temperature processing or (less often) ultra-heat treatment (both abbreviated UHT) is the partial sterilization of food by heating it for a short time, around 1–2 seconds, at a temperature exceeding 135°C (275°F), which is the temperature required to kill spores in milk” (Bylund, 1986). Thus, UHT treatment means exposing the milk to a powerful heat treatment so that all the micro-organism will be killed and the output product is qualitative for long use even in ambient temperature. If such type of technology if brought in Nepal it would be benefit to the farmer many people will get engaged for the purpose and it will certainly bring change in socio-economic life of the, use of the cheap type of vehicles, return the extra products (unsold) will be the benefit and helps in developing economy of the Nation.

Key Words:

HTST, Partial Sterilization.

http://en.wikipedia.org/wiki/Sterilization_(microbiology)

http://en.wikipedia.org/wiki/Food



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Brief Scenario of Dairy Technology in Nepal While talking about the “Modern milk processing began in the early nineteen-fifties with the introduction of Swiss alpine cheese making technology to the high mountains” (Upadhyaya, 2001) then there is the establishment of a cheese factory in Langtang, Rasuwa district, with financial assistance from New Zealand and technical assistance from FAO (Food and Agriculture Organization).Near about the same time Milk processing plant was was established at Kharipati, Bhaktapur.1958 A.D; was the first time the milk was process and marketing was started. After two year pasteurized milk in aluminum foil-capped bottles was on sale in Kathmandu (Upadhyaya, 2001). Butter in consumer packs, cream, yoghurt and ice cream were introduced later by the government owned Central Dairy at Lainchour. After Nine years i.e. Dairy Development Corporation (DDC) was established. As earlierly it carried dairy development over the country. As there is the increasing demand for processed milk and dairy products the DDC progressed by establishing more milk supply schemes as shown in the Table I:

S.no. Project name

Established date

Major Products

Plant Capacity

1. Kathmandu Milk Supply Scheme, Balaju Industrial District, Balaju, Kathmandu

2037 B.S Pasteurised Milk, Butter, Ghee, Flavoured Milk

15,000 Lts per hour(75,000 Lts Per shift)

2. Biratnagar Milk Supply Scheme, Kanchanwari, Biratnagar

2030 B.S Standard and Full Cream Milk, Butter, Cream, Ghee, SMP((Skim Milk Powder)

5000 Lts per hour

3. Hetauda Milk Supply Scheme, Hetauda Industrial District, Hetauda

2032 B.S Standard and Full Cream Milk, Butter, Cream, Ghee, Ice-Cream, Peda, Lalmohan, Yoghurt, Paneer

5000 Lts per hour



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4. Lumbini Milk Supply Scheme, Butwal

2046 B.S Standard and Full Cream Milk, Ghee, Yoghurt, Rasbari

1000 Lts per hour

5. Mid Western Milk Supply Scheme

2045 B.S Milk Collection

_

6. Milk Product Production & Supply Scheme, Lainchour, Kathmandu

_

Yak Cheese, Kanchan Cheese, Spread Cheese, Mozeralla Cheese, Paneer, Ghee, Yoghurt,Ice-Cream, Rasbari, Jeera Mohi, Gundpak

_

Table: I. Dairy Development Corporation (DDC). Source: http://www.dairydev.com.np/mppss.htm

In 1992, HMG Nepal established a National Dairy Development Board (NDDB) to assist dairy development. In the late nineteen-seventies private entrepreneurs began to establish small processing units in the Kathmandu valley. There are more than 200 private dairies of various scales in operation all over the country; their market share has increased continually from 33 percent in 1991-92 to 40 percent in 1998-99 (NDDB, 2001). Cheese production by the private sector is about 224 tons per year which is more than that produced by DDC (176 tons). Over viewing about the present technology, Available dairy technology in Nepal can be divided into two different categories including Pasteurizing and Skim Powder Technology. At present condition Nepal has no UHT Technology; The UHT products are imported from the Country like China and India.

Traditional indigenous technology of Nepal.

Imported western technology. Consumption of milk and dairy products is a part of Nepalese culture. Dahi (curd), ghee, chhurpi, khoa and khoa-based sweets are the main traditional commercial dairy products; mohi and khir are non-traditional dairy ones and in imported Technology many technological advances have been taken place in the production of dairy products and

http://www.dairydev.com.np/mppss.htm



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packaging for longer shelf life. At present in Nepal products from western dairy technology are pasteurized milk, cheese, butter, ice-cream, and milk chocolate. Key Words:

SMP, Yoghurt, shelf life.

Framework for the Processing of the UHT Milk. While Observing the Economy Of under-developing Country like Nepal, its economy is totally based on Agriculture and Animals husbandry: 61.5% of the total Population according to census 2001 (Dhruba Lal Rajbamshi, 2005). As the country‟s Nepal with its population of 25.3 million has an annual per capita of US $ 240(Dhruba Lal Rajbamshi,2005); that place Nepal at one of the poorest countries in the world and they are living on low productivity agriculture, cattle rearing, related casual work and lack techniques increase, improve and preserve their products.So, Ultimate focus is to develop the socio-economic status of the rural areas of people by utilizing the agro raw materials and help to promote them in this field by creating the oppuritinites with the research for this type of appropriate technology which can be fruitful to them. Milk is as ancient as mankind itself, as it is the substance created to feed the mammalian infant. Milk production began 6,000 years ago, or even earlier. The dairy animals of today have been developed from untamed animals which, over thousands of years according to (Wikipedia Website), have lived at different altitudes and latitudes, at times exposed to natural and, many times, severe and extreme conditions. Today, the milk consumption (as fluid milk and processed products) widely from highs in Europe and North America to lows in Asia. When we observe the basic need of the people food and cloths, people use from Animals; The foremost thing is that farmers are like god they produce food to all the people of the world but still they are very poor. Dairy farming/milk production will be the effective opportunities to them to improve their economic status. It would be efficient from the government or either private sector to promote the farmer for it and appropriate to technology which helps and can be an inspiration and attraction to them by utilizing the Knowledge and skills of available skilled people inside or outside of the country. In this mechanism, the economic well being of many families would be secured. Many data‟s and Recent Technology even says that the dairy technology has lot of its sufficient potentials to overcome with the problems of the large proportion of the rural population by changing the



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traditional method by developing with some appropriate type of new technology. They will not have to think about the tomorrow‟s food and children care. Their cattle can be tangible asset and for their security. Dairy farming with the processing will helps in many aspects like rural employment, food production, helps to build economy and nutritional food health in a country. It also helps the people to self-dependent and essential inputs to their crop production. Milk Production in Nepal involves many of the small producers each of them raising one or two cows, buffalos in terrain belts and hilly belts and Yak in the Himalayan belts. The farmer are not getting the actual cost there will be the gap loss in during milking, handling, processing and transportation called milk adulteration. The important aspects to reduce this losses is to develop a small processing and packaging to increase value and shelf life of the milk is the necessity in the rural areas of Nepal.

Processing of UHT. Origin of UHT Technology. Louis Pasteur was the first person to carry out experiments on sterilization of milk in bottles, but it was not until around 1960 (Bylund, 1986) when both aseptic processing and aseptic filling technologies became commercially available, that the modern development of UHT processes started. UHT-treated milk also some of the process also used for fruit juices, cream, yogurt, wine, soups, and stews. The first UHT plant operated on the principle of direct steam injection. Compared with the in-container sterilization plants, the new UHT plants soon gained a reputation for producing an excellent flavor. The first indirect plant was introduced on the market some ten years later. Research and development have been intense since UHT was first introduced. Modern plants deliver a superior product with colour and nutritional values practically unchanged.

Microbiological and Heat Treatment Standards for UHT. For the milk there are different microbiological standards from many year research set by the council of the European Union (EU) for the safeguard human and animal health, are shown in the Table I and II. And another factor to be considered is about the heat treatment which has become the most important part of milk processing and its influence is important. The various categories of heat treatment have been initiated as shown in Table II and III.

S.no. Products Plate count Colony Forming Unit(CFU mlG1)

1. Raw milk <100 000

http://en.wikipedia.org/wiki/Cream

http://en.wikipedia.org/wiki/Yogurt

http://en.wikipedia.org/wiki/Wine

http://en.wikipedia.org/wiki/Soup

http://en.wikipedia.org/wiki/Stew



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2. Raw milk stored in silo at the dairy for more than 36 hours

<200 000

3. Pasteurized milk <30 000

4. Pasteurized milk after incubation for 5 days at 8°C <100 000

5. UHT and Sterilized milk after incubation for 15 days at 30°C

<10

Table II. Showing Standards for bacteria count in milk: Source: EU Standards for bacteria count in milk, in force 1 January 1993.

S.no Process Temperature (°C)

Time

1. Thermisation 63-65 15 Sec

2. LTLT pasteurization of milk 63 30 min

3. HTST pasteurization of milk 72-75 15-20 Sec.

4. HTST pasteurization of cream > 80 1-5 Sec.

5. Sterilization in container 115-120 20-30 min

6. UHT (flow sterilization) 135-140 A few seconds

Table III. Showing categories of heat treatment in the dairy industry. Source: Source: EU Standards for bacteria count in milk, in force 1 January 1993.

Heat Treatment Process in UHT Thermisation It is a process of heat treatment applied to raw milk to reduce the number of organisms in milk and allowing longer storage of the milk prior to further processing. In many large dairies it is purpose of heat treatment is to kill all micro-organisms capable of causing disease. “Many dairies therefore pre-heat the milk to a temperature below the pasteuration temperature, to temporarily inhibit bacterial growth. This process is called thermisation. The milk is heated to 63 – 65 °C for about 15 seconds, a time/temperature combination that does not inactivate the phosphatase enzyme. Double pasteurisation is forbidden by law in many countries, so thermisation must stop short of pasteurisation conditions.”

(Bylund, 1986). Pasteurized milk must be entirely free from pathogens. The actual

time/temperature combination varies according to the quality of the raw milk, the type of product treated and the required keeping properties. Cream is heated to a temperature above 80°C, with the holding time of about 5 seconds. Sterilization “Sterilization” is a process which causes complete destruction of microorganisms and their spores. In conventional Sterilization is the original form of sterilization which involves in-container sterilization usually at temperatures from 115-120°C for 20-30 minutes. In case of commercial sterilization it does not always meet this definition, because some



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harmless, heat resistant bacteria may still be present. The criterion for food sterility remains to be a process, which will ensure no surviving botulism bacteria or their spores. The original form of sterilization, still used, is in-container sterilization, usually at 115-120°C for some 20-30 minutes. After fat standardization, homogenization and heating to about 80°C, the milk is packed in clean containers-usually glass or plastic bottles for milk and cans for evaporated milk. The product, still hot is transferred to autoclaves in batch production or to a hydrostatic tower in continuous Production. Logarithmic reduction of spores:

Mathematically,

The lethal effect of sterilization on micro-organisms can be expressed as the logarithmic function to the left,

K x t = log N/Nt,

The denotation of the symbol Says, N = number of microorganisms (spores) originally present. Nt = number of microorganisms (spores) present after a given time of treatment (t), and K = a constant t = time of treatment.

No. of survivors

Duration of treatment (t)

Graph I. Semi-logarithmic graph

From the Graph: I,

As there is impossible for a logarithmic function to approach zero, which concluded that the absence of living bacterial spores in an unlimited volume of product is impossible to



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achieve. So, it would be better to look for more workable & realistic concept rather than applying demands that are impossible and cannot be determined under practical condition. LTLT pasteurization: This method is called the holder method or the low-temperature-long-time method. This is a typical batch method where a quantity of milk is placed in an open vat and heated to 63°C and held at that temperature for 30 min. Sometimes filled and sealed bottles of milk are heat-treated in shallow vats by that method and subsequently cooled by running water. Nowadays milk is almost always heat treated in continuous processes like thermisation, HTST pasteurization or UHT treatment.

HTST pasteurization: The term is an abbreviation of high-temperature-short-time. The HTST process for milk involves heating it to 72-75°C with a holding time of 15-20 seconds before it is cooled. Depending upon the quality of the raw milk and the degree of refrigeration, the shelf life may be from 2 days to 16 days. The primary purpose of heat treatment is to kill all micro-organisms capable of causing disease. Pasteurized milk must be entirely free from pathogens. The actual time/temperature combination varies according to the quality of the raw milk, the type of product treated and the required keeping properties. The HTST process for milk involves heating it to 72 – 75 °C with a hold of 15 – 20 seconds before it is cooled. The phosphate enzyme is destroyed by this time/temperature combination. The phosphate test is therefore used to check that milk has been properly pasteurized. The test result must be negative; there must be no detectable phosphate activity (Figure1).

Production of long life milk: There are two methods used for the production of long life milk they are shown in the chart as below:

.

Production of UHT Milk

In-Container

sterilization. (With product in package

(container) being heated

at about 115-120°C for

20-30 minutes. Ambient

storage.)

.

UHT-treatment.

(With the product heated at

135-150°C for 4-15 seconds

followed by aseptic

packaging in packages

protecting the product against

light and atmospheric

oxygen. Ambient storage.)

Pressure Vessels



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.

Chart II: Showing the different method used in the processing of UHT; Source: (Bylund, 1986).

Operating Phases in UHT: There are many UHT system and it vary according to the different processes but all the system uses the same operating phases and they are generalized as: Pre-sterilization: In the beginning of the Production Plant the plant must be pre-sterilized in order to avoid reinfection of the treated product. There are Heating and cooling part in the involve in pre-sterilization: Hot water sterilization at the steam temperature as the product shall Undergo. Minimum time of the hot water sterilization is 30 minutes from the moment the relevant temperature has been reached in the whole aseptic part of the plant and In cooling the plant to conditions required for production. Production: Heating medium and product are not in direct contact, but separated by equipment contact surfaces. There are several type of Heat exchangers are applicable they may be Plate, Tubular, Scarped Surface. The production phases vary according to the different processes and classified as:

1. Direct UHT Plants:

Direct UHT plant based on steam injection and plate heat exchanger. Direct UHT plant based on steam injection and tubular heat exchanger.

Batch Processing.

Continuous Processing

Vertical

Hydrostatic

Towers.

Horizontal

Sterizers.

Rotatory Cage

Rotatory Autoclave



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Direct UHT plant based on steam infusion.

2. Indirect UHT plants: Indirect UHT plant based on plate heat exchangers. Indirect UHT plant based on tubular heat exchangers. Indirect UHT plant based on scraped surface heat exchangers. The production phases vary according to the different processes. The procedure described here is of the indirect UHT plant based on plate heat exchanger. The product at about 4°C is pumped from the storage tank to the balance tank of the UHT plant and from there by the feed pump to the regenerative section of the plate heat exchanger. In this section the product is heated to about 75°C by the UHT treated milk, which is cooled at the same time. The preheated product is then homogenized at pressure 180-250 bars. The preheated, homogenized product continues to the heating section of the plate heat exchanger where it is heated to about 137°C The heating medium is a closed hot-water circuit with the temperature regulated by steam injection in to the water. After heating, the product passes through the holding tube dimensioned for about 4 seconds. Finally, cooling is performed regeneratively in two sequences: First against the cool end of the hot water circuit and then against the cold incoming product. The product that leaves the regenerative cooler continues directly to aseptic packaging or to and aseptic tank for intermediate storage. At temperature drop during production the product is diverted into a reject tank and the plant is flushed by water. The plant must be cleaned and sterilized before restart. If one of the packaging machines incidentally stops the aseptic tank take care of the surplus product during the stoppage



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1 Balance tank, 2 Feed pump, 3 Plate heat exchanger, 4 Non-aseptic homogenizer, 5 Valve, 6. Holding tube, 7 Aseptic filling, 8. CIP, 9.Motor, 10. Homogenizer, 11.Aspetic Tank, 12. Aseptic Filling Machine. Source: Dairy processing Hand Book, Chapter-9, Page number: 240, Figure I: UHT process with heating by indirect heating in plate heat exchanger.

Direct heating systems The product is heated by direct contact with steam of potable or culinary quality. The main advantage of direct heating is that the product is held at the elevated temperature for a shorter period of time. For a heat-sensitive product of milk, this means less damage.

The product is heated by direct contact with steam of potable or culinary quality. The main advantage of direct heating is that the product is held at the elevated temperature for a



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shorter period of time. For a heat-sensitive product such as milk, this means less damage. There are two methods of direct heating:

1. Injection type 2. Infusion type

Injection: High pressure steam is injected into pre-heated liquid by a steam injector

leading to a rapid rise in temperature. After holding, the product is flash-cooled in a

vacuum to remove water equivalent to amount of condensed steam used. This method

allows fast heating and cooling, and volatile removal, but is only suitable for some

products. It is energy intensive and because the product comes in contact with hot

equipment, there is potential for flavor damage.

Infusion: The liquid product stream is pumped through a distributing nozzle into a chamber of high pressure steam. This system is characterized by a large steam volume and a small product volume, distributed in a large surface area of product. Product temperature is accurately controlled via pressure. Additional holding time may be accomplished through the use of plate or tubular heat exchangers, followed by flash cooling in vacuum chamber. This method has several advantages:

Instantaneous heating and rapid cooling No localized overheating or burn-on Suitable for low and higher viscosity products

Indirect heating systems The heating medium and product are not in direct contact, but separated by equipment

contact surfaces. Several types of heat exchangers are applicable:

Plate Tubular Scraped surface

In between the direct heating and indirect heating system there is difference in

temperature which provides the reduction in the product damage range.



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Graph II. Profile of Direct and Indirect heating system with temperature and time variable.

Source: (Gosta Bylund, 1986)

The profile of the graph in Direct and Indirect Sterilization is produced in the graph above

which clearly indicates that there is reduction in product damage range.

Plate Heat Exchangers

Similar to that used in HTST but operating pressures are limited by gaskets. Liquid

velocities are low which could lead to uneven heating and burn-on. This method is

economical in floor space, easily inspected, and allows for potential regeneration.

Tubular Heat Exchangers There are several types:

Shell and tube Shell and coil Double tube Triple tube

All of these tubular heat exchangers have fewer seals involved than with plates. This



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allows for higher pressures, thus higher flow rates and higher temperatures. The heating is

more uniform but difficult to inspect.

Scraped Surface Heat Exchangers: The product flows through a jacketed tube, which contains the heating medium, and is scraped from the sides with a rotating knife. This method is suitable for viscous products and particulates (< 1 cm) such as fruit sauces, and can be adjusted for different products by changing configuration of rotor. There is a problem with larger particulates; the long process time for particulates would mean long holding sections which are impractical. This may lead to damaged solids and over processing of sauce. There are many Advantages and some difficulties with UHT they are explained below:

Advantages of UHT: High quality: The D and Z valves are higher for quality factors than microorganisms. The reduction in process time due to higher temperature (UHTST) and the minimal come-up and cool-down time leads to a higher quality product. Long shelf life: Greater than 6 months, without refrigeration, can be expected. Packaging size: Processing conditions are independent of container size, thus allowing for the filling of large containers for food-service or sale to food manufacturers (aseptic fruit purees in stainless steel totes). Cheaper packaging: Both cost of package and storage and transportation costs; laminated packaging allows for use of extensive graphics.

Difficulties with UHT:

Sterility:

Complexity of equipment and plant are needed to maintain sterile atmosphere between

processing and packaging (packaging materials, pipework, tanks, pumps); higher skilled

operators; sterility must be maintained through aseptic packaging

Particle Size:

With larger particulates there is a danger of overcooking of surfaces and need to transport

material - both limits particle size.

Equipment:

There is a lack of equipment for particulate sterilization, due especially to settling of solids

and thus over processing.



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Keeping Quality:

Heat stable lipases or proteases can lead to flavor deterioration, age gelation of the milk

over time - nothing lasts forever! There is also a more pronounced cooked flavor to UHT

milk.

Packaging for Aseptic Processing

The Aseptically processed liquid foods and beverages are sterilized outside the package

using an ultra-high temperature process that flash heats and cools the product before

containers are filled. Time (generally 3 to 15 seconds) and temperature (90° to 140°C)

(Bylund, 1986). are tailored to place the least amount of thermal stress on the product,

while ensuring bacteriological safety. The sterile food product is then placed in an air-tight

sterilized package with a within a hygienic environment. This preserves the food without

chemical preservatives or refrigeration. The most important point to remember is that it

must be sterile. All handling of product post-process must be within the sterile

environment.

There are 5 basic types of aseptic packaging lines:

1. Fill and seal: preformed containers made of thermoformed plastic, glass or metal are sterilized, filled in aseptic environment, and sealed 2. Form, fill and seal: roll of material is sterilized, formed in sterile environment, filled, sealed e.g. tetrapak 3. Erect, fill and seal: using knocked-down blanks, erected, sterilized, filled, sealed. e.g. gable-top cartons, cambri-bloc 4. Thermoform, fill, sealed roll stock sterilized thermoformed, filled, sealed aseptically. e.g. creamers, plastic soup cans 5. Blow mold, fill, seal:

There are several different package forms that are used in aseptic UHT processing: Cans Paperboard/plastic/foil/plastic laminates Flexible pouches Thermoformed plastic containers Flow molded containers Bag-in-box Bulk totes

It is also worth mentioning that many products that are UHT heat treated are not aseptically packaged. This gives them the advantage of a longer shelf life at refrigeration temperatures compared to pasteurization, but it does not produce a shelf-stable product at ambient temperatures, due to the possibility of recontamination post-processing.

http://www.foodsci.uoguelph.ca/dairyedu/chem.html#gelation



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Discussion and Conclusion The important thing is that the product Of UHT remains fresh without Refrigeration which can be used at anytime and anywhere. The great advantage of the UHT product is that it can be transport to a long distance; every part of the country due to its property of safe in drinking with good keeping quality (i.e. for several months).The technology is suitable in a country like Nepal because of its various Advantages and till date there is no such Technology of Processing long Life to Milk. As these Technology will not only provide Opportunities for the market, it will increased the employment from farmer to skilled manpower and aware about the Technology. The Dairy farm integrated with the UHT processing plant can be a new opportunities for Industrialization in rural part of the country and can cut-off importing the product from China and India. With the increment of the UHT product can exported outside Nepal. Beside these, milk is unsuitable for UHT treatment if it is sour and it has wrong salt balance. There is little difference in the flavor of the milk due to the high temperature. Also it is a expensive process due to expensive packaging which cannot be eliminated. With these many Advantages and Opportunities and a little bit of difficulties, It will be fruitful to the Government as well as private sectors for making investment will not only benefit to them but it will create employment opportunities to the people of the country.

Acknowledgement



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Seminar Paper on “UHT (Ultra-High Temperature) Technology for Processing of Long-life

Milk: A Prospects in Nepal.” Would be incomplete if I could not acknowledge some of the

personals who directly and indirectly help me to work out.

Firstly, I would like to thank Associate Prof.Dr.Bim Parsad Shrestha, Kathmandu

University,Dhulikhel,Kavre. Associate Prof.Dr.Panmannas Sinbourn. King Mongkut's

Institute of Technology, Landranbang,Bangkok, Thailand & Assistant Director of DPO

Mr.Suwarat Hongtarachai for their fruitful suggestion in preparing the seminar.

I am very much thankful to my supervisors Mr.Suat Chai & Miss.Nan Fon of UHT system in

Dairy Farming Promotion Organization, Muak Lek who help me in each and every step of

the seminar in the data collection and guide me through every system and expand my

knowledge about th

References: To procure more particulars about the seminar paper, the below listed literature serve as a guide. 1. Gosta Bylund, 1986. Dairy Processing Handbook, TetraPak processing systems AB, S-221, Sweden. 2. Chatterjee, A.K. and R.M. Acharya, 1992. Heading for 21st Century, Dairy India,

Delhi, pp: 4-24. 3. Douglas Goff, 2006. UHT Processing. University of Guelph, Canada. Available online

at: http://www. foodsci.uoguelph.ca/dairyedu/uht.html 4. Gedam Kishor, Prasad Rajendra and Vijay V.K, 2007 World Journal of Dairy & Food

Sciences, IDOSI Publications 5. Mair-Waldberg Heinrich,PHD, Volkwirtschaftlicher Verlag GmbH, Kempten, (Allgäu),

Germany, Handbuch der Käse. 6. Davis J.G., A Dictionary of Dairying, Leonard Hill, London, UK. 7. Fox P.F. Developments in Dairy Chemistry, Volume 1 – 4, Applied Science

Publishers, London and New York. 8. Spreer Edgar, Milk and Dairy Product Technology. 9. Kammerlehner. J., Lab-Käse-Technologie, Band I, II, III, Verlag Th. Mann,

Gelsenkirchen, 1986. 10. http://en.wikipedia.org/wiki/Wine. 11. Shrestha R.Tilak,Associate Professor,Tribhuwan University; “Nation Biosaftey

Framework in Nepal”, Regional Biosecurity Workshop, Bangkok, Thailand, December 7-9,2007.

http://en.wikipedia.org/wiki/Wine



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Annex: List of Tables Table I. Dairy Development Corporation (DDC). Source: http://www.dairydev.com.np/mppss.htm Table II. Showing Standards for bacteria count in milk: Source: EU Standards for bacteria count in milk, in force 1 January 1993. Table III. Showing categories of heat treatment in the dairy industry. Source: EU Standards for bacteria count in milk, in force 1 January 1993. List of Charts Chart I. Showing the UHT milk as a percentage of total consumption at present in different countries of the world. Source: www.wikipedia.org/UHT milk.htm Chart II: Showing the different method used in the processing of UHT; Source: (Bylund, 1986). Figure I: UHT process with heating by indirect heating in plate heat exchanger. Source: Dairy processing Hand Book, Chapter-9, Page number: 240

List of Graph Graph I. Semi-logarithmic graph Graph II. Profile of Direct and Indirect heating system with temperature and time variable.

Source: (Gosta Bylund, 1986)

http://www.dairydev.com.np/mppss.htm

http://www.wikipedia.org/UHT%20milk.htm



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“Questioner Interview with Engineer of Tetra Pak”

Mr.Ann is an Electrial Engineer at Tetra Pak a Swedesh Dairy and Beverage Machinery Manufacturer Company and he had more than 10 year of Working Experience in the field of UHT system and Aseptic filling machine from Tetra pak. During my Training I got chance to meet him and he help me a lot in understanding about the UHT systems. I had a interview with him during my training which are as below:

1. Why the UHT Technology is Popular in the world? Answer: “If low cost and highly effective technology for preservation of milk can be implemented in country, it can be beneficial to the people as an opportunity. UHT treatment for milk, dairy material means the application of heat to a continuously flowing milk or liquid dairy material using such high temperatures for such time that renders the product commercially sterile at the time of processing. When the UHT treatment is combined with aseptic packaging, it results in a commercially sterile dairy product that is sufficient to ensure that the product remains microbiologically stable after incubating, thereby reducing the spoiling of nutrients and has excellent keeping qualities and stored for long period of time at ambient temperature”.

2. What is Important in the UHT system in dairy processing?

Answer: “Aseptic packaging machines are very expensive and UHT milk depends entirely on it. There is a need to reduce its cost so that UHT processing and packaging machine and it plays a very important role in the UHT system og dairy processing”

3. What is the major Advantages of the UHT system then Pasteurization system?

Answer:

“High quality, Long shelf life, Packaging size and Cheaper packaging is the major advantages.



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4. Is there any Disadvantages or drawbacks of the UHT Products?

Answer: “Complexity of equipment and plant are needed to maintain sterile

atmosphere between processing and packaging (packaging materials,

pipework, tanks, pumps); higher skilled operators; sterility must be maintained

through aseptic packaging & There is a lack of equipment for particulate

sterilization, due especially to settling of solids and thus over processing” are

the major drawbacks of the UHT system.

Some Photographs of UHT Systems:

Whole UHT System Packging material web at Aspetic filling Machine



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Index:

Abstract Brief Scenario of Dairy Technology in Nepal Framework for the Processing of the UHT Milk. Framework for the Processing of the UHT Milk. Processing of UHT. Origin of UHT Technology Microbiological and Heat Treatment Standards for UHT Heat Treatment Process in UHT

Thermisation

Sterilization

LTLT Pasteurization HTST Pasteurization Operating Phases in UHT

Pre-sterilization

Production:



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1. Direct UHT Plants 2. Indirect UHT Plants

Direct heating systems Indirect heating systems Plate Heat Exchangers Tubular Heat Exchangers Scraped Surface Heat Exchangers Advantages of UHT Difficulties with UHT Packaging for Aseptic Processing Discussion and Conclusion Acknowledgement References Annex

List of Tables

List Of Chart

List Of Graph

“Questioner Interview with Engineer of Tetra Pak”.

Some Important Photographs of the UHT System.



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“UHT (ULTRA-HIGH TEMPERATURE) TECNOLOGY FOR PROCESSING OF LONG LIFE MILK A PROSPECT IN NEPAL.”

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