Lesson 4 - General Food Preservation Principles PDF

PRINCIPLES & FOOD METHODS OF PRESERVATION By: Rachel M. Pardiñas  Definition of Food Processing and Preservation Principles of Food Preservation FLOW OF Causes of Spoilage DISCUSSION Historical Methods of Food Preserva...

PRINCIPLES & FOOD METHODS OF PRESERVATION By: Rachel M. Pardiñas  Definition of Food Processing and Preservation Principles of Food Preservation FLOW OF Causes of Spoilage DISCUSSION Historical Methods of Food Preservation Methods of Food Preservation 2  Activity Why does fresh bread go bad? Why do fresh donuts go bad? Why do packaged bread or donuts not go bad? 0 What is Food 0 Food Processing Food processing requires good quality raw materials from either plant and/or animal  is the set of methods and source to be converted into attractive, marketable and often long shelf-life food techniques used to transform products. raw ingredients into food or to transform food into other forms for consumption by humans or animals either in the home or by the food processing industry Food Preservation “ science which deals with the process of prevention  Methods of treating foods to of decay or spoilage of food thus allowing it to be stored in a fit condition for future use”. delay the deterioration of the food.  Changing raw products into more stable forms that can be stored for longer periods of time.  Allows any food to be available any time of the year in any area of the world. Objectives  Making food safe for consumption  Removal of unwanted matter from food  Increases digestibility  Enhance flavor, color & taste  Improves texture and consistency  Minimize nutrient loss  Extending shelf life Importance Increase the shelf life of food Retain the quality of food (color, texture, flavor, nutritional value) Increase food supply Adds variety to the foods Decrease wastage of food Make food available in off season  Food processing and preservation are interrelated, as food is preserved to ensure quality before being packed for processing Food processing mostly involves both packaging and preservation, while food preservation is concerned with the control and elimination of the agents of food spoilage 0 Principles of Food Preservation 0 PRINCIPLES OF FOOD PRESERVATION 1. Prevention or delay of microbial decomposition 2. Prevention or delay of self – decomposition of the food 3. Prevention of damage by insects, rodents, animals, mechanical causes etc.  INHIBIT OR DELAY OF MICROBIAL DECOMPOSITION Keeping out Removal of Hindering the growth Killing the micro-organisms microorganisms (asepsis) microorganisms of activity of i.e., by heat or radiations. microorganisms, i.e., by filtration i.e., by low temperature, drying, anaerobic conditions etc.  Keeping out microorganisms ASEPSIS – process of keeping microorganisms out of food and its surroundings.  A state of being free from spoilage microbes – bacteria , fungi etc. Egs : Shells of nuts, almonds, walnuts ,egg etc. Skins of fruits – banana, orange  Packaging – prevents the entry of microbes Keeping out microorganisms (asepsis)  Use of clean vessels, hygienic surroundings – help to prevent spoilage of milk during collection and processing by keeping out microorganisms. Removal of microorganisms  For the preservation of clear liquids – water, fruit juices, beer, soft drinks etc.  Use “ bacteria proof” filters made up of asbestos pad, unglazed porcelain – candle filters. Microbes can also be removed by: Removal of microorganisms  Centrifugation(Treatment of drinking water)  Washing raw foods  Trimming away spoiled portions of food.  Hindering the growth of activity of microorganisms  Use of low temperature  Preservation of food at refrigeration temperatures – increases the lag phase of many microorganisms and thus prevents their growth in foods.  Drying  Sun drying  Mechanical drying Hindering the growth  Binding the moisture with addition of sugar or salt of activity of microorganisms, and making it unavailable to microbes.  Water content of food is reduced- below a certain level - microorganisms can not grow.  Hindering the growth of activity of microorganisms  Maintenance of anaerobic conditions prevent the growth of aerobes. e.g. Canned food – canned pea, mush rooms, baby corns etc. Fruit juices in airtight containers – Care should be taken to kill or inactivate anaerobic bacteria (Clostridium botulinum ) and their spores.  Use of chemical preservatives Sodium benzoate Potassium metabisulphite Hindering the growth Sorbic acid of activity of Calcium propionate microorganisms, Antioxidants –prevent rancidity (development of off-flavours in edible oils) e.g. Butylated Hydroxy Anisole (BHA), Butylated Hydroxy Toluene (BHT), Lecithin.  Killing the microorganisms  Heat - Exposing food to high temperature kills most of microorganisms.  Irradiation - should be used with caution  Use of UV lamps to sterilize knives in bakeries  α, ß and Ƴ rays for preservation of vegetables , fruits, sea foods etc. Killing the microorganisms PRESERVATION OR DELAY BY SELF - DECOMPOSITION OF FOOD Destruction or inactivation Inhibit or delay of chemical of food enzymes reactions (non-enzymatic (phenolase) browning) eg-: blanching )eg:- preservation of oxidation by means of an antioxidant.  Destruction or inactivation of food enzymes (phenolase)  Destroying or inactivating food enzymes Blanching is an example of this kind of prevention Low temperature Chemical preservatives Destruction or inactivation Drying of food enzymes (phenolase)  Preventing oxidation with the use of antioxidants  Preventing oxidation with the use of antioxidants Oxygen speeds up decomposition of food, antioxidants deprives food from oxygen. Ex. Butter, margarine and other fatty foods Inhibit or delay of chemical reactions (non-enzymatic browning) PREVENTION OF DAMAGE BY INSECTS, RODENTS, ANIMALS, MECHANICAL CAUSES ETC. Food Name 0 Causes of Food 0 Bacteria prefer protein rich foods e.g. meat, fish, poultry, eggs, and dairy products. These are known as High Risk Foods. 25 0 Historical Methods of Food Preservation 0 Primitive and tedious methods DRYI SALTING SUGARI PICKLIN COLD STORAGE NG NG G  Drying DRYIN  Used to preserve fruit, G vegetables, meats, and fish.  Mainly used in the south – warmer climate.  Causes the loss of many natural vitamins.  Salting SALTIN  Used extensively for pork, G beef, and fish.  Costly due to high price of salt.  Done mainly in cool weather followed by smoking.  Sugaring SUGARIN  Used to preserve fruits for G the winter.  Jams and jellies.  Expensive because sugar was scarce commodity in early times.  Pickling  Fermenting PICKLI NG  Used to preserve vegetables.  Use mild salt and vinegar brine.  Increases the salt content and reduces the vitamin content of the food.  Oldest form of food preservation.  Cold Storage COLD STORA  Used extensively in the northern GE U.S.  Root cellars were used to store vegetables at 30-40 degrees F.  Root cellars were replaced by ice boxes in the mid 1800’s.  Refrigeration  Early time, ice and snow was REFRIGERATI used. ON  Now the most popular method of food preservation.  85% of all foods are refrigerated.  Greatly changed our eating habits.  Refrigeration REFRIGERAT  Refrigerators should be set to ION below 4°C to control the growth of micro-organisms in foods.  This lowered temperature also reduces the respiration rate of fruits and vegetables, which retards reactions that promote spoilage.  Refrigeration is generally used to:  reduce spoilage during distribution of REFRIGERAT perishable foods; ION  increase the holding period between harvesting and processing; and  extend the storage life of commercially processed foods.  Not all foods benefit from cold temperatures.  For example, bananas turn black and bread goes stale when refrigerated Heating  Started in 1800’s.  Known as canning – putting hot food in jars to seal.  Food is cooked to extremely high temperatures, put into jars and lids are placed on them.  Lids are sealed from the heat and this prevents bacteria from growing and spoiling the food.  Bacteria grow at any temperature between 5– 60 C. This temperature 0 range is known as the Danger Zone. 37 0 Methods of Food 0  Physical Processing THERMAL METHODS Blanching- Destruction of enzymatic activity, maintain color, texture, flavor and nutritive values in fruits & vegetables.It is a pre-treatment done before canning, drying and freezing. Temperature is below 100˚c Boiling - Destroys vegetative cells of bacteria, yeast and molds. Temperature is 100˚c  Blanching Advantage Disadvantage –Improves taste –Storage limits Fruits & veggies 1 –Increases year availability of Meat 3-6 months out of season Freezing foods temperatures required for Pasteurization It is a mild heat treatment in which food is heated below 100˚c. Effective for kiling pathogenic micro-organisms  A food preservation process that heats liquids to 160°F (71°C) for 15 seconds (HTST), or  143°F (62°C) for 30 minutes, in order to kill bacteria, yeasts, and molds Sterilization  The elimination of all microorganisms through extended boiling/heating to temperatures much higher than boiling or through the use of certain chemicals.  For eg, milk sterilization is done at 300F(148.9C) for 1-2 sec. Canning -food content is sealed in an airtight containers(jars, steel and tin cans). During heating process air is driven out of the jar and as it cools a vaccum seal is formed. This vacuum seal prevents air from getting back into the product bringing with it contaminating microbes. Enhances shelf life (upto5 yrs) Suitabe for high & low acidic foods  Hot water canning - 212˚F at sea level, time varies with product  Pressure canning- 240˚F  Canning Advantages Disadvantages –Increases shelf life –Weight of product –2 years is –Requires specially considered normal treated metal cans shelf life or appropriate glass jars. Drying -Inhibitsthe growth of bacteria, yeasts and molds. sufficient moisture is removed (aw), which is essential for enzyme activity& microbes. Examples:- raisins, guava, apple, dates, papaya, figs  Natural methods - shade drying  Mechanical methods – oven ,kiln, tunnel , belt trough ,fluidized bed ,foam mat, spray, vacuum puffing ,drum, microwave, freeze, pneumatic dryers Factors affecting drying rate: Temperature Velocity of air Surface area Size of the product Tray load Relative humidity of air Atmospheric pressure and vacuum Moisture content of food  Dehydration Disadvantages Advantages – –Changes Increasestaste shelf and texture of life up to 2 years food –Lighter weight –Typically requires –Lower volume preparation to reconstitute food. LOW TEMPERATURE PRESERVATION Freezing – inhibit microbial growth by lowering water activity  Air freezing- air blast freezers, fluidized bed freezing ,tunnel freezing temperature = (-18˚c to -40˚c), velocity =1.5- 6 m/s  Plate freezing  Liquid immersion freezing  Cryogenic freezing – liquid NO2  Deep and quick freezing  Freeze drying Chilling- temperature(0 to-5˚c), reduction in free liquid water activity thud depriving micro-organisms of the water they need to metabolize.  Immersion chilling  Air chilling Refrigeration - tempertaure (-15 to -25˚c)  Bulking  Shelfing  Boxing TYPES OF NON THERMAL PRESERVATION TECHNIQUES IRRADIATION  Exposing food to inonizing radiation, such as gamma rays, X-rays or electron beam without direct contact to the food product.  Destroys micro-organisms causing spoilage and food borne illness and inhibiting sprouting/ ripening and control insects and invasive pests. Depending upon the dosage:  Micro-organism destroys  Slowed down  Incapable of reprodution  Ex: sprouting in potato, onion ,garlic DOSES  Inhibit sprouting= (0.06-0.2 kGy)  Delay in ripening=(0.5-1.0 kGy)  Prevent insect infestation=(0.15-1.0 kGy)  Parasite control= (0.3-1.0 kGY)  Extend shelf life (raw meat)=(1.0-5.5 kGy)  Extend shelf life(frozen meat)=(4.5-7.0 kGy)  Pathogenic &spoilage microbes=(1.0-7,=.0 kGy)  Reduction in cooking time(dried veg)=(3.0-7.0)kGy  Enzymes =(10.0 kGy)  Sterilization (spices,veg seasonings)=10.0 kGy  Sterilization foods (NASA)= (44.0 kGy)  Packaging sterilization=(10-25 kGy)  Irradiation Advantage Disadvantages ––Gamma High costrays pass through without –Perception of heating or changing irradiation it, therefore no heat sensitive nutrients are lost in the process Ultrasound Microbial inactivation - cavitation process (changes the pressure and temperature ) break down of cell walls, disruption and thinning of cell membranes and DNA damage.  Transient cavitation  Stable cavitation- Methods:-  Ultrasonication  Thermosonication  Manosonication  Manothermosonication- DOSES  Microorganism inactivation= ultrasonic waves (20kHz,D value=4.3min) and (200kPa,1.5-1.0 min)  Spore inactivation =500kPa for 12 min(manosonication), 20kHz at 300kPa(sonication)  Enzyme inactivation=1000Pa at 5000K(lipoxygenase and polyphenol oxidase) APPLICATIONS  Filteration&drying  Freezing  Mixing & homogenization  Defoaming  Crystallization of fats,sugars  Cutting  Degassing  Pulse electric field short pulses of high electric fields(few micro-milliseconds) with intensity in the range of (10-80kV/cm) for microbial inactivation and causes minimal detrimental effect on food quality attributes. o Gram +ve are more resistant than gram –ve o Spores are highly resistant o Yeast more sensitive than bacteria o PEF inactivates yeast, pathogens & spoilage M.O Mechanism: 1. Electrical breakdown 2. Electroporation Uses- milk & dairy products, juices, enhancement of juice extraction Juice processing- increase mass transfer coefficient due to cell membrane permeabilisation. Applications:  Sugar processing- disintegration and destruction of cell membrane at 70-78˚c  Plant oil extraction- oil recovery improved by 7.4%at 1.3kV/cm soya bean oil – iso-flavonoid content increases  Meat & fish- improve mass transfer and accelerate, curing Ohmic Heating Food material , which serves as an electrical resistor,is heated by passing electricity through it. Electrical energy is dissipated into heat, which results in rapid and uniform heating.  Heating rate = 1 to 10˚c/s Mechanism: 1. Thermal inactivation 2. Electroporation (50-60Hz) uses  Meat processing- Reduce cooking time of brine cured meat(>0.5Kg/min) Quicker and uniform thawing  Milk processing- HTST ohmic pasteurization(goat milk)  Fruit &vegetable processing- reduces loss of solid (upto50%) ohmic blanching-enhance water and surface transfer High pressure processing(HPP or pascalization) Food products are processed under very high pressure, leading to the inactivation of certain micro-organisms (vegetative cells)and enzymes o Range for Food – (400-600MPa) for 2 minutes or greater o Temp of product rises 3-6˚c for every 100 Mpa Principle:  Le chateliar’s principle  Isostatic principle DOSES  Inactivation of (milk) enzymes= (1000MPa)  Commercial food products= (600MPa)  Increasing milk shelf life = 600MPa for 60 min(4 days) Inactivates: parasites Vegetative cells Fungal spores Food borne viruses Selected enzymes Suitable for:  Low medium moisture,semi-solid, vacuum foods  High moisture,solid foods, vacuum packed Filteration Reduces microbial population or sterilizes solutions of heat sensitive materials by removing micro-organisms. 1. Depth filters Thick fibrous / granular filters that removes micro-organisms by physical screening, entrapment or adsorption 2. Membrane Filters porous membrane with defined pore sizes that removes micro-oraganisms primarily by physical screening. Antimicrobials  Bactericide: chemical that destroys bacteria(not spores)  Fungicide: chemicals that kills fungal spores,hyphae, yeasts  Virucide: chemical that inactivate virus  Sporicide: can destroy bacterial endospores  Germicide and microbicide: kills micro-organisms  Bacteriostatic: prevent growth of bacteria Examples- methyl,ethyl,propyl and butyl arabens, sorbic acid ,Na,K& Ca sorbate,Benzoic acid ,Na,K&Ca benzoate, sodium Metabisulphite, propylene glycol, BHT, BHT, benzaldehyde , essential oils, phenol and mercury compounds  CHEMICAL PROCESS Preservatives Chemicals used to retard food spoilage caused by micro-organisms &prolong shelf life. 1. Traditional:  Salting- contains chlorine, harmful for microbes(causing dehydration)  Sugaring- increase osmotic pressure , Aw=