1 1 Teacher Professional Development Programme Teacher Professional Development Programme Knowledge Enriching Series for Knowledge Enriching Series for New Senior Secondary Technology and Living: New Senior Secondary Technology and Living: Food Science and Technology Strand Food Science and Technology Strand Item 1: Food Studies Item 1: Food Studies Food Preservation I Food Preservation I Professor Peter CK Cheung Professor Peter CK Cheung Food and Nutritional Sciences Food and Nutritional Sciences The Chinese University of Hong Kong The Chinese University of Hong Kong
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Teacher Professional Development ProgrammeTeacher Professional Development ProgrammeKnowledge Enriching Series forKnowledge Enriching Series for
New Senior Secondary Technology and Living:New Senior Secondary Technology and Living:Food Science and Technology StrandFood Science and Technology Strand
Item 1: Food StudiesItem 1: Food Studies
Food Preservation IFood Preservation IProfessor Peter CK CheungProfessor Peter CK Cheung
Food and Nutritional SciencesFood and Nutritional SciencesThe Chinese University of Hong KongThe Chinese University of Hong Kong
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Outlines for Food Preservation I and IIOutlines for Food Preservation I and II
Purpose of food preservationPurpose of food preservationFactors causing food deteriorationFactors causing food deteriorationPrinciples of food preservationPrinciples of food preservationThermal and nonThermal and non--thermal methods of thermal methods of food preservationfood preservationEmerging methods of preservationEmerging methods of preservation
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What is Food Preservation?What is Food Preservation?
It is an action or a method of maintaining It is an action or a method of maintaining foods at a desired level of properties/ foods at a desired level of properties/ characteristics or nature for as long as characteristics or nature for as long as possiblepossibleuse of specific thermal and use of specific thermal and nonthermalnonthermalprocessing techniques to minimize processing techniques to minimize microbial spoilage and extending the microbial spoilage and extending the shelfshelf--life of foodslife of foods
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Examples of food preservation Examples of food preservation throughout historythroughout history
Milling of cereal grains into flour [~10,000 BC]Milling of cereal grains into flour [~10,000 BC]Baking unleavened bread [10,000 BC]Baking unleavened bread [10,000 BC]Meat and fish smoking, salting and drying [~4,000 BC]Meat and fish smoking, salting and drying [~4,000 BC]Canning [1800s AD]Canning [1800s AD]Milk pasteurization [1800s AD]Milk pasteurization [1800s AD]FreezeFreeze--drying [1900s AD]drying [1900s AD]Modified atmosphere packaging [1900s AD]Modified atmosphere packaging [1900s AD]Food irradiation [1900s AD]Food irradiation [1900s AD]NonthermalNonthermal preservation [2000 AD]preservation [2000 AD]
55Source: Ancient Food Technology by Robert I. Curtis
66Source: Ancient Food Technology by Robert I. Curtis
77Source: Ancient Food Technology by Robert I. Curtis
88Source: Ancient Food Technology by Robert I. Curtis
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Storage
Sale
Consumption
Harvesting
Processing
Transport
Storage
Packaging
Storage
Distribution
Foodprocessors
Consumers
Food ingredients
Fresh foods
Figure 1. Various stages of food production, manufacture, storage, distribution, and sale.
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What are foods?What are foods?
Foods are materials, raw, processed, or Foods are materials, raw, processed, or formulated, that are consumed orally by formulated, that are consumed orally by humans or animals for growth, health, humans or animals for growth, health, satisfaction, pleasure, and satisfying satisfaction, pleasure, and satisfying social needssocial needs
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Different classes of foods Different classes of foods include:include:
Perishable and NonperishablePerishable and NonperishableHarvested and FreshHarvested and FreshMinimally ProcessedMinimally ProcessedPreservedPreservedManufactured and FormulatedManufactured and FormulatedPrimary and Secondary DerivativesPrimary and Secondary DerivativesSyntheticSynthetic
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12 months12 monthsNonperishableNonperishableGrains, pulses, seeds, and Grains, pulses, seeds, and nutsnuts
Table 1. Storage Life of Some Fresh Foods at Normal Atmospheric Conditions
Source: Rahman, M. S. 1999. In: Handbook of Food Preservation. Rahman, M. S., Ed. Marcel Dekker, New York. pp. 1-9.
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Why food needs to be Why food needs to be preserved?preserved?
To preserve quality and nutritive values To preserve quality and nutritive values of foodsof foodsTo overcome inappropriate planning in To overcome inappropriate planning in agriculture, agriculture, To prevent spoilage and eliminate wasteTo produce valueTo produce value--added products, and added products, and To provide variation in dietTo provide variation in diet
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Figure 1. Unit operations for fruit and vegetable canning
Pumping
Harvesting
Receiving
Washing
Peeling, Husking, Pitting, Coring, etc.
Separating, Grading, Sorting for size, Color, Solids and Defective removal
Holding by Quality
Blanching
Dewatering
FillingExhausting
Container Closing
To warehouse
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How long to preserve?How long to preserve?
When one or more quality attributes of a When one or more quality attributes of a food has reached an undesirable state or food has reached an undesirable state or level defined by manufacturer according level defined by manufacturer according to criteria when the product is saleableto criteria when the product is saleableUnsuitable for consumptionUnsuitable for consumptionShelfShelf--lifelifeBestBest--before date or pack datebefore date or pack dateUseUse--by date or expiration dateby date or expiration date
CrystallizationCrystallizationFlavor encapsulationFlavor encapsulationPhase changesPhase changesRecrystallizationRecrystallizationShrinkageShrinkageTransport of Transport of componentcomponent
Source: Gould, G. W. 1989. In: Mechanisms of Action of Food Preservation Procedures. Gould, G. W., Ed. Elsevier Applied Science. London; Gould, G. W. 1995. In: New methods of Food Preservation. Gould, G. W., Ed. Blackie Academic and Professional, Glasgow
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b. Indirectly by spreading diseasesb. Indirectly by spreading diseasesa. Directly by consuming fooda. Directly by consuming food
3.3. RodentsRodentsb. Indirectly by spreading diseases (b. Indirectly by spreading diseases (fruitflyfruitfly, housefly), housefly)a. Directly by eating (infestation)a. Directly by eating (infestation)
2.2. Insects and mitesInsects and mitesd. Protozoad. Protozoac. Phagesc. Phagesb. Bacteria b. Bacteria a. Fungi: mold and yeasta. Fungi: mold and yeast
1.1. MicroorganismsMicroorganisms
Table 3. Organisms That Spoil Foods
Source: Borgstrom. G. 1968. Principles of Food Science. Macmillan, London.
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Categorization of Major Food Categorization of Major Food Preservation MethodsPreservation Methods
Inhibition of microbial growthInhibition of microbial growthSlowing down of chemical deteriorationSlowing down of chemical deteriorationDirect inactivation of bacteria, yeasts, or Direct inactivation of bacteria, yeasts, or enzymesenzymesAvoiding recontamination before and Avoiding recontamination before and after processingafter processing
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Food preservation methods
Inhibition Inactivation Avoid recontamination
Low-temperature storageReduction of water activityDecrease of oxygenIncrease of carbon dioxideAcidificationFermentationAdding preservativesAdding antioxidantsControl pHFreezingDryingConcentrationSurface coatingStructural modificationsChemical modificationsGas removalChanges in phase transitionHurdle technology
SterilizationPasteurizationIrradiationElectrifyingPressure treatmentBlanchingCookingFryingExtrusionLightSoundMagnetic field
PackagingHygienic processingHygienic storageAseptic processingHACCPGMPISO 9000TQMRisk analysis and management
Source: Gould, G. W. 1989. In: Mechanisms of Action of Food Preservation Procedures. Gould, G. W., Ed. Elsevier Applied Science, London; Gould, G. W. 1995. In: New Methods of Food Preservation. Gould, G. W., Ed. Blackie Academic and Professional, Glasgow.)
Figure 3. Major food preservation techniques
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Food Preservation by Food Preservation by InhibitionInhibition
Control of external environment Control of external environment (temperature, atmosphere, humidity, etc.)(temperature, atmosphere, humidity, etc.)Control of intrinsic properties of foods Control of intrinsic properties of foods (water activity or pH value)(water activity or pH value)
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Preservation of dried fruitsPreservation of dried fruits
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Food Preservation by Use of Food Preservation by Use of Chemicals/Additives*Chemicals/Additives*
To control pHTo control pHAs As antimicrobesantimicrobesAs antioxidantsAs antioxidantsSynthetic and natural sourcesSynthetic and natural sourcesRiskRisk--benefit analysisbenefit analysis
* More details to be covered in Food Science and Technology Extended Studies under the topic of Industrial Food Production (Food Processing – Use of Food Additives)
bread, cake, cheese foodsbread, cake, cheese foodsbacteria, moldsbacteria, moldsNa and Ca propionateNa and Ca propionate
ketchup, jams, syrups, orange juice ketchup, jams, syrups, orange juice products, syrupsproducts, syrups
molds and yeastsmolds and yeastsbenzoic acid saltbenzoic acid salt(sodium benzoate)(sodium benzoate)
bread; as vinegar in pickled products bread; as vinegar in pickled products and mayonnaiseand mayonnaise
bacteria, moldsbacteria, moldsacetic acid salt acetic acid salt (sodium acetate)(sodium acetate)
Some Food ApplicationsSome Food ApplicationsEffective AgainstEffective AgainstAntimicrobial CompoundAntimicrobial Compound
Table 4. Types and properties of antimicrobial substances used in the food processing industry.
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Preservation of bakery Preservation of bakery productsproducts
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Preservation of sausagesPreservation of sausages
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Sausage (Frankfurter) makingSausage (Frankfurter) making
A comminuted meat emulsion, showing protein matrix of muscle fibers, collagen fibers, and emulsified fat droplets surrounded by a film of myofibrillar protein
Preparation of the casingWashing and trimmingGrindingPrepare the meat emulsionEmulsion stuffingCooking/RoastingStorage
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Table 5 Formulation of a typical Frankfurter
30 gmSugar
0.25 gm5 ml
Sodium nitriteLiquid Smoke
70 gm45 gm
Skim milk powderSalt
0.6 gmCardamom400 gmIce
2.5 gm1.1 gm
NutmegAscorbic acid
900 gmPork trimmings (20-30% fat)
6.2 gm3.7 gm
White pepperCoriander
1100 gmBoneless beef (10-12% fat)
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Table 6 Table 6 Functional ingredients in processed meatFunctional ingredients in processed meat
Acts as antioxidantActs as antioxidantErythorbateErythorbate
Provides calorie reduction (fat Provides calorie reduction (fat replacerreplacer); carries and distributes ); carries and distributes dry ingredients; contributes to juiciness and tendernessdry ingredients; contributes to juiciness and tenderness
WaterWater
Binds to water; facilitates browning reactions; provides Binds to water; facilitates browning reactions; provides sweetness to counteract salt; acts as substrate for sweetness to counteract salt; acts as substrate for fermentationfermentation
SugarSugarContribute specific flavors; inhibit bacterial growthContribute specific flavors; inhibit bacterial growthSpicesSpices
Inhibits spoilage and pathogenic organisms; contributes to Inhibits spoilage and pathogenic organisms; contributes to flavor; prevents warmedflavor; prevents warmed--overover--flavor; stabilizes colorflavor; stabilizes color
Nitrite (NONitrite (NO22--))
Nitrite is the active form; antioxidant that slows rancidityNitrite is the active form; antioxidant that slows rancidityNitrate (NONitrate (NO33--))
FunctionsFunctionsIngredientIngredient
Several common processed meat ingredients and their functions.
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Preservation of pickled foodsPreservation of pickled foods
Foods containing animal fatsFoods containing animal fatsSurvives baking and fryingSurvives baking and fryingBHTBHTcc
Foods containing animal fatsFoods containing animal fatsSurvives baking and fryingSurvives baking and fryingBHABHAbb
MeatsMeatsComplexes with metal ionsComplexes with metal ionsPhosphatesPhosphatesMeatsMeatsChelateChelate metals in meatmetals in meatCitric acidCitric acidVegetable oilVegetable oil--containing foodscontaining foodsSlow oxidation by metalsSlow oxidation by metalsEDTAEDTAaa
Food Preservation by Control Food Preservation by Control of Waterof Water
Water content and water activityWater content and water activityRemoval of water by drying and Removal of water by drying and concentrationconcentrationFreezingFreezing
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Figure 4
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Preservation Preservation of pastaof pasta
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Food Preservation by Control of Food Preservation by Control of Atmosphere (Packaging Techniques)Atmosphere (Packaging Techniques)
Preservation of packaged cakesPreservation of packaged cakes
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Preservation of rice cakePreservation of rice cake
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Preservation of potato chipsPreservation of potato chips
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Food Preservation by Food Preservation by InactivationInactivation
Use of heat energyUse of heat energyUse of radiation Use of radiation Use of high pressure and ultrasound*Use of high pressure and ultrasound*Use of electricity*Use of electricity*Use of magnetic field*Use of magnetic field*
* Emerging technologies
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Preservation of dairy products Preservation of dairy products
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Preservation of cooked foodsPreservation of cooked foods
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Preservation of canned foodsPreservation of canned foods
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Food Preservation by Food Safety Food Preservation by Food Safety Concepts/SystemsConcepts/Systems
Hazard Analysis and Critical Control Hazard Analysis and Critical Control Point (HACCP)Point (HACCP)ISO 9000 and 22000 ISO 9000 and 22000 Good Manufacturing Practices (GMP)Good Manufacturing Practices (GMP)Standard Operating Procedures (SOP)Standard Operating Procedures (SOP)Total Quality Management (TQM)Total Quality Management (TQM)Hurdle Technology/Combined Hurdle Technology/Combined Preservation TechniquesPreservation Techniques
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Example of application of hurdle Example of application of hurdle technology in food preservationtechnology in food preservation
Figure 5
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Suggested Suggested basic rbasic readingeading
Handbook of Food Preservation by M.S. Handbook of Food Preservation by M.S. RahmanRahman (2007), 2nd edition, CRC Press(2007), 2nd edition, CRC PressFood Preservation Techniques by P. Food Preservation Techniques by P. ZeuthenZeuthen and L. and L. BoghBogh--Sorensen (2003), Sorensen (2003), WoodheadWoodhead PublishingPublishingUnderstanding Food Science and Understanding Food Science and Technology by Peter S. Technology by Peter S. MuranoMurano (2003)(2003), , ThompsonThompson