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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

33--4 weeks4 weeksSemiperishableSemiperishableRoot cropsRoot crops

11--2 weeks2 weeksSemiperishableSemiperishableFruits and vegetablesFruits and vegetables

11--2 days2 daysPerishablePerishableMeat, fish, and milkMeat, fish, and milk

Storage LifeStorage LifeTerminologyTerminologyFoodFood

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

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Quality

Safety

Choice

Unsafe• Level of micro-flora• Pathogens• Microbial toxins• Parasites• Toxic chemicals• Radioactive hazards

• Advertisement• Public knowledge• Social factor• Economic factor• Consumer age• Media report• Past experience• Attitude• Expectation

Emotional factors

Food properties

• Sensory• Nutritive• Functional• Convenience

Figure 2. Factors affecting food quality, safety, and choice.

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Factors causing food Factors causing food deterioration and spoilagedeterioration and spoilage

MechanicalMechanicalPhysicalPhysicalChemicalChemicalEnzymatic Enzymatic Microbial effectsMicrobial effects

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Bruising due to Bruising due to vibrationvibration

CollapseCollapseColor lossColor lossBrowningBrowningMicroorganism Microorganism growthgrowth

Damage due to Damage due to pressurepressure

CrystallizationCrystallizationFlavor encapsulationFlavor encapsulationPhase changesPhase changesRecrystallizationRecrystallizationShrinkageShrinkageTransport of Transport of componentcomponent

NonenzymaticNonenzymaticbrowningbrowningNutrient lossNutrient lossOxidationOxidation--reductionreductionRancidityRancidity

OffOff--flavorflavorToxin productionToxin production

CrackingCrackingControlled releaseControlled releaseFlavor lossFlavor lossColor Color changechange

OffOff--flavorflavor

MechanicalMechanicalPhysicalPhysicalChemicalChemicalEnzymaticEnzymaticMicrobiologicalMicrobiological

Table 2. Major Quality-Loss Mechanisms

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)

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dried fruit, lemon juice, molasses, dried fruit, lemon juice, molasses, wineswines

bacteria, yeast, moldbacteria, yeast, moldsulfite, sulfur dioxide (SOsulfite, sulfur dioxide (SO22))

baked products, fruit preserves, baked products, fruit preserves, meatsmeats

bacteria, yeast, moldbacteria, yeast, moldsugar (sucrose)sugar (sucrose)

condiments, fruit juicescondiments, fruit juicesmolds and yeastsmolds and yeastssodium benzoatesodium benzoate

cured meat productscured meat productsClostridiumClostridiumsodium nitritesodium nitrite

baked products, canned foods, baked products, canned foods, meatsmeats

bacteria, yeast, moldsbacteria, yeast, moldssalt (sodium chloride)salt (sodium chloride)

breadsbreadsbacteria, moldsbacteria, moldspotassium potassium sorbatesorbate

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

Cure ingredient; extracts Cure ingredient; extracts myofibrillarmyofibrillar proteins; provides flavor; proteins; provides flavor; tenderizestenderizes

SaltSalt

Increase juiciness; inhibit rancidity; retain moisture; Increase juiciness; inhibit rancidity; retain moisture; solubilizesolubilizeproteinsproteins

PhosphatesPhosphates

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

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Comminuted poultry, meat, fishComminuted poultry, meat, fishAvoid warmed overAvoid warmed over--flavorflavorThyme, oreganoThyme, oreganoMeats, irradiated ground beefMeats, irradiated ground beefDelay free radical formationDelay free radical formationRosemaryRosemary

Sausage and other ground Sausage and other ground meatmeat

Retard lipid oxidationRetard lipid oxidationDried plumsDried plums

Ground turkeyGround turkeyDarker is more effectiveDarker is more effectiveHoneyHoney

Foods containing animal fatsFoods containing animal fatsCan add with vitamin C, etc.Can add with vitamin C, etc.TocopherolsTocopherolsVegetable oilVegetable oil--containing foodscontaining foodsHeat sensitiveHeat sensitivePropylPropyl gallategallateVegetable oilVegetable oil--containing foodscontaining foodsSurvives frying temperatureSurvives frying temperatureTBHQTBHQdd

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

ApplicationsApplicationsAction/CharacteristicsAction/CharacteristicsAntioxidantAntioxidant

Table 7. Some Chemical and Natural Antioxidants and Their Uses

aEthylenediaminetetraacetic acid bButylated hydroxyanisolecButylated hydroxytoluene dTertiary-butylhydroquinone

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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)

Modified atmosphere packagingModified atmosphere packagingControlled atmosphere packagingControlled atmosphere packagingActive packagingActive packagingVacuum packagingVacuum packagingAscepticAsceptic packaging (avoid packaging (avoid recontamination)recontamination)

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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