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by: Karl Kerluke


Karl Kerluke
GPA 3.99


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This 35 page Class Notes was uploaded by Karl Kerluke on Saturday September 12, 2015. The Class Notes belongs to FDST 4010 at University of Georgia taught by Shewfelt in Fall. Since its upload, it has received 57 views. For similar materials see /class/202552/fdst-4010-university-of-georgia in Food Science & Technology at University of Georgia.

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Date Created: 09/12/15
Spring 2011 FOOD SCIENCE 4010 Lecture 19 Chilling and modified atmospheres PR1NIPLEamp Food deteriorates mainly spoilage biologically Microbes chemically and physically physical often caused by chemical deterioration Pathogens can dominate and keep food from spoiling longer bad Food processing and preservation is designed to slow or prevent food deterioration Biological deterioration is by microbes or senescence Chemical deterioration proceeds by oxidation or browning Physical deterioration can be result of chemical deterioration Physical deterioration include moisture loss or breakdown of texture Microbial growth in foods can preserve them spoil them or make them unsafe 4 types of microbes in foods fermentated yeasts molds free riders don39t do anything spoilage pathogens Preservation of foods by fermentation Spoilage microbes slime off colors off flavors Safety problems infections intoxications must inactivate toxin Spoilage is not a good indicator of safety hazards Controlled atmosphere storage involves the monitoring of gas composition and maintaining composition within given tolerances want C02 and oxygen to be at certain levels preserve fresh foods for long periods of times like apples onions CAS involves compete monitor and control of the atmosphere It can involve the addition and removal of gases It is in large storage sheds Modified atmosphere storage and packaging involves setting of the initial gas composition but provides little or no control you set intial concentration fresh fruit or vegetable starts using 02 and releasing C02 need to know storage conditions how long will be stored if all 02 used up gt fermentation MAS starts the process at a certain gas composition Composition changes based on the respiration rate of the fruit or vegetable Must carefully calculate what the ultimate gas compositions would be C02 and 02 MAP is the most widely used form of MAS Active packaging responds to changing conditions in the package Active packaging can involve edible coatings looks like less packaging but same effect Can contain ethylene scavengers Oxygen scavengers to slow lipid oxidation Automatic openings In chips put N2 in to lessen amt of 02 prevent oxidationprotect flavor Food Processing Technology Chapter 21 DISCUSSION QUESTIONS What are the four components in a single stage mechanical refrigeration system How does each component function 615 616 Compressor condenser expansion valve evaporator Refrigerant enters the compressor from the low pressure side of the cycle gt compressed to higher pressure in superheated region the outlet pressure from the compressor must be below the critical pressure of the refrigerant and high enough to enable condensation of the refrigerant by a cooling medium During compression enthalpy temperature and pressure of refrigerant increased Size of compressor determines owrate and pressure Operating pressure depends on the type of refrigerant and the required evaporator temperature Condenser cool air or water passing through the condenser coils absorbs heat from the hot refrigerator vapor causes it to condense back to liquid state Superheat removed first then latent heat of condensation Enthalpy falls back down but pressure remains constant The liquid refrigerant then passes at a controlled rate through the expansion valve which separates the high and low pressure parts of the cycle at a constant enthalpy Refrigerant pressure falls back down some of refrigerant changes to gas Evaporator liquid refrigerant under reduced pressure and in doing so absorbs latent heat of vaporization and cools the freezing medium Freezing medium can be the relatively warm air in a coldroom water brine or food owing over the evaporator coils Refrigerant evaporates to become a saturated vapor Enthalpy increases pressure remains constant The refrigerant than goes back to compressor What are the properties needed in selecting mechanical refrigerants 625 low boiling pt and high critical temp above critical temp refrigerant vapor cannot be lique ed High latentheat of vaporization to reduce the volume of refrigerant required A dense vapor to reduce the pressure required in the compressor and hence the size and cost of the compressor low toXicity and nonflammable Noncorrosive and having lowmiscihility With oil in the compressor Chemicall y stable and not environmentally damaging in the event of leakage low cost What is cryogenic chilling How does it differ from other types of chilling 619 kkz Total loss refrigerant that cools foods by absorbing latent heat as it changes phase Use solid C02 dry ice used in meat processing liquefied C02 or liquefied nitrogen Main limitation can cause asphyXia Cold burns frostbite and hypothermia from eXposures to intense cold Used in food transportation keeps it really cold VERY cold temp Compare the optimal storage temperature optimal humidity possible us of ice or water sprinkle production and sensitivity to ethylene and storage life of cucumbers peaches strawberries and winter squash Cucumbers Optimal storage temp 10 1 5C 95 humidity Don t use ice or water sprinkle Very low production of ethylene sensitive to ethylene 10 14 days Peaches Optimal storage temp 5 0 C 90 9 5 humidity Don t use ice or water sprinkle high production of ethylene sensitive to ethylene 2 4 weeks Strawberries Optimal storage temp 0C 90 95 humidity Don t use ice or water Very low production of ethylene not sensitive to ethylene 3 7 days Winter squash 0C 50 70 humidity Don t use ice or water no production of ethylene sensitive to ethylene 1 6 months How do climacteric fruits differ from nonclimacteric What are the implications for fresh storage Climacteric apples bananas tomatoes ripening caused by plant hormone ethylene C2H4 abrupt increase in rate of respiration and huge increase in C02 production which occurs near to the point of optimal ripeness Can be picked at full size and maturity but before it s ripe then ripen off plant Non climacteric all vegetables grapes cherries orange produce little or no ethylene no large increases in C02 production maintain qualities they have at harvest Climacteric fruits produce ethylene can ripen each other fastest need to produce around of ethylene produced Climacteric fruits shorter time between picking and getting it to market cannot be stored long term Melons are in between climacteric or non climacteric Spring 2011 FOOD SCIENCE 4010 Lecture 20 Freezing PRINCIPLES Freezing stops microbial growth in foods a lot like drying making water unavailable As water freezes it becomes unavailable to microbes Freeze concentration increases reactivity in unfrozen part of the food once thawed back out same water availability most of microbes stay in tact not killed by freezing getting freeze concentration when you reduce water gradual process part of it freezes at a time water left is concentrated can get increase in rxn rather than decrease concentrating solutes Enzymes can act at slow rates unless below the glass transition temperature can get rxns going on bc of molecular mobility lose quality because of chemical rxns rather than microbes Glass transition temp VERY cold much below freezer each food has its own the food becomes like a glass frozen solid so no molecular mobility no enzyme rxns no chemical rxns Freezing doesn t kill microbes at least not massively The faster the rate of freezing the higher the quality of the product Faster freezing minimizes freeze concentration going much more quickly from completely water to completely ice Fast freezing forms small ice crystals big ice crystals are a problem in live tissue foods destroys membranes hurts quality break membrane around vacuole acid flows out and causes browning like in apple Super cooling as you apply cold temps to freeze something go down to 25C or 24C but no ice crystals can then freeze very quickly to avoid nucleation warm temp gradually after freezing Small ice crystals do less damage to cells Large ice crystals break membranes leading to leakage and accelerated damage in thawed foods Intermittent thawing damages food quality when you thaw something out get freeze concentration bad and microbes can start growing Any time you thaw something out you get freeze concentration Constant freeze thaw leads to loss of quality Get crystal formation which destroys membranes Loss of flavor amp nutrition Proper packaging is necessary to protect frozen foods Problem with air Loss of water leads to surface dehydration called freezer burn sublimation straight from solid to gaseous state do this in freeze drying freeze solidly then lower the pressure Proper packaging prevents moisture loss water can39t escape Prevents water migration from surface moisture migration can hurt flavor color and texture in frozen foods Frozen pizzas have benefited from advances in food technology Reactants may concentrate in unfrozen pizza during freezing or thawing can lose compartmentation esp in tissue items can lose flavor if spices are just sitting there Edible coatings soggy crusts tomato sauce pizza sauce used to soak into crust soggy crust now use edible coatings on crust keeps sauce from crust now lower temperatures in freezer Fast acting yeasts now used in rising crust pizzas yeast activated by time it39s thawed heated Extra low freezer temperatures Food Processing Technology Chapter 2 2 DISCUSSION QUESTIONS How does water content and the freezing point differ in vegetables fruits meat fish milk and egg Vegetables 78 92 water content 8 to 28C Fruits 87 95 moisture 9 to 27C Meat 55 70 moisture l7 to 22C Fish 65 81 moisture 06 to 20C Milk 87 moisture 05C Egg 74 moisture 05C How does solute concentration affect freezing rate What foods are most likely to be affected Why Makes the freezing rate slower more damage done to food need to get to lower temp for glass transition temp Thermal conductivity solute concentration Foods such as fruits low glass transition temp apples bananas grape juice higher sugar content Ice cream meats Alcoholic beverages freeze water but still have unfreezed alcohol eutetic point Higher solute How do pressure freezers work What are the advantages and disadvantages of using them Increase pressure during freezing and thawing lowers freezing temp and raises freezing rate involves cooling High pressure assisted freezing 21C under high pressure High pressure shift freezing pressure instantly released food freezes very quickly lce nucleation get a few crystals formed and then get a lot of crystals formed ADV Influences ice water transition and prevents many undesirable changes to teXture and sensory properties of foods creates smaller more uniform ice crystals reduced biochemical damage reductions in microbial and enzyme activity higher retention of nutrients reduced damage to avor color and teXture less mechanical damage to cells small ice crystals Reduces drip after thawing DIS in uences proteins enzymes cellular tissues and microorganisms Muscle foods can cause toughness bc of aggregation of myfibrillar proteins Cells in some fruits and vegetables less damaged than blast freezing but may not lead to better fappearance teXture or water retention Not sufficient enzyme deactivation still need blanching microbial inactivation might not be sufficient High capital costs pay up front What is cryogenic freezing What products are most amenable to cryogenic freezing Cryogen uid w much lower temperature use a change of state in the refrigerant to absorb heat from the freezing food Heat provides the latent heat of vaporization and sublimation of the cryogen cryogen in intimate contact w food to remove heat rapidly usu use liquid nitrogen or liquid or solid carbon carbon dioxide airc02 currents created in freezer Sublimation of C02 or nitrogen draws a lot of heat out remaining by air mixture Fish seafood mushrooms onion rings and meat Cryogenic freezing can make things brittle causes cracking p667 cryogens How does isomass recrystallization differ from accretive recrystallization 680 Isomass recrystallization Change in surface shape or internal structure usu resulting in a lower surface are to volume ratio Accretive recrystallization Two addacent ice crystals join together to form a larger crystal and cause an overall reduction of the of crystals in the food Neither one as important as microtory Spring 2011 FOOD SCIENCE 4010 Lecture 21 Freeze drying freeze concentration and coating PR1NIPLEamp Sublimation permits the conversion of ice directly to moisture vapor freeze then put under pressure eliminate freezer burn Triple point if you can get below triple pt fig on pg 689 and pg 208 straight from icesolid to gas state all has to do with pressure reduces freezer burn combination of temperature and pressure Direct conversion of ice to vapor Sublimation goes to 15 moisture Then by evaporative drying of unfrozen water to 2 moisture very hard to get below 2 The glass transition temperature of a food represents the point at which all molecular mobility ceases no cmpnds from glass into food or food into glass minus 40C Glassy state both physical and chemical implications physical frozen solid Molecular mobility no molecules moving around no rxns Molecular mobility reduced by the removal of water or freezing Within tissue foods vegetables fruits meats in same state not ground membranes protect enzymes from substrates create compartmentation Never get all water frozen but immobilized Solutes affect glass transition temp moisture content protein content fat content Freeze concentration effects dramatically change the chemical environment inside a food change by 10C 2x change in rxn rate Freezing results in lowering temp amp freeze concentratio Reaction rates do not conform well to kinetic approaches at subfreezing temperatures Some reactions actually accelerate at freezing temperatures Below glass transition all water is not frozen but it is immobile Chocolate lipids melt just below body temperature Unique property of chocolate lipids Property that makes it hard to create artificial chocolate High in saturated fat Europeans add vegetable oils to their chocolate Solutes moisture content fat content protein content all affect glass transition temp Conching is a slow mixing process that improves flavor and texture of chocolate products 48 72 hours in which other ingredients are added slow mixing process mixers going back and forth for 48 72 hrs Breaks down fine particles difference between the brittle texture of Baker s chocolate and the smooth texture of Hershey kisses Conching affects smoothness viscosity and flavor of milk chocolate Conching also provides kneading and aeration to open up the structure by incorporating air Lipid oxidation can happen when exposed to air but chocolate lipids don39t oxidize very much have saturated fats need at least 2 bonds for lipid oxidation Food Processing Technology Chapters 2 3 amp 24 DISCUSSION QUESTIONS How is heat transferred to the sublimation front 3 methods 1 Heat of transfer through the frozen layer Rate of heat transfer controlled by the thickness and thermal conductivity of the ice layer As drying proceeds the thickness of the ice is reduced and the rate of heat transfer increases The heater temperature is limited to avoid melting the ice If heating by microwaves involves thermoconductivity 2 Heat transfer through the dry layer The rate of heat transfer to the sublimation front depends on the thickness and area of the food the thermal conductivity of the dry layer and the temperature difference btwn the food and the ice front The dried layer of food has a very low conductivity and therefore offers a high resistance to heat ow as drying proceeds this layer becomes thicker and the resistance increases As in other unit operations a reduction in the size and thickness of the food and an increase in the temperature difference increases the rate of heat transfer However in freeze drying the surface temperature is limited to 40 65C to avoid denaturation of proteins and other chemical changes that would reduce the quality of the food 3 Dielectric heating Heat is generated directly at the ice front and the rate of heat transfer is not influenced by the thickness of the dry layer or the thermal conductivity of ice or dry food However dielectric heating is less easily controlled and because water has a higher loss factor than ice if any ice is melted there is a risk of localized runaway overheating How do conduction contact freeze driers work What types of foods would be best for conduction freeze drying Food is placed on ribbed trays that rest on heated shelves Dries more slowly than other methods heat is transferred by conduction to only one side of food There is uneven contact btwn the frozen food and the heated surface which also reduces the rate of heat transfer Pressure drop through the food that results in in difference btwn the drying rates of the top and bottom layers However contact freeze dryers have higher capacity than other types Liquid products slurries that are frozen Soups milk coffee juices What are the ways freeze concentrates can be separated from ice Wash columns most common way 995 efficiency works by feeding the ice concentrate slurry from the crystallizer into a vertical cylinder crystals are compressed to and concentrate is discharged through a filter and recirculated to the re crystallizer the packed bed of crystals is then washed using melted ice that is forced through the packed bed by increasing the pressure on the column Less commonly can use centrifugation 50 efficiency filtration like vacuum ltration 71 efficiency or filter pressing 89 95 efficiency Freeze concentration of liquid food involves the fractional crystallization of water to ice by freezing and subsequent removal of the ice using wash columns or mechanical separation techniques What factors affect the enrobing of products with chocolate Thickness of the coating is determined by 1 Temperature of both the food and the coating 2 The viscosity of the coating flow characteristics determined by ratios of sugar starch and fat more fatthinner coating 3 The speed of the air in air blowers 4 The rate of cooling Type and composition of the centers of the confections What is microencapsulation What are some of the applications Microencapsulation a process in which minute particles or liquid droplets are coated with a thin film of edible encapsulating material Applications 1 To protect volatile ingredients or those that are heat sensitive or susceptible to oxidation and nutritional loss during processing and storage eg colors vitamins avorings or essential oils For example the artificial sweetener ampartame is a dipeptide that broken down by heat resulting in a loss of sweetness Microencapsulated aspartame in bakery products is protected from heat and sweetness is retained in the final product 2 To mask the odor of an ingredient eg fish oils or plant eXtracts used in functional foods or incorporation of nutrients and development of nutraceutical foods 3 To contain a reactive ingredient eg to separate a food acid from other ingredients to prevent color and flavor changes in the food or to enable time release mechanisms in an ingredient formulation in a product eg microencapsulated sodium bicarbonate in home baked pizza or bread doughs prevents the early release of bicarbonate and delays the reaction of leayening phosphate until the crust reaches a specific temperature in the oven 4 To control the time and rate of release of enzymes and starter cultures 5 Transformation of liquids into easily handled solid ingredients Spring 2011 FOOD SCIENCE 4010 Lecture 22 Packaging theory and materials PR1NIPLEamp The most important functions of the primary food package material that comes into direct contact w product are to contain the product and prevent contamination Importance of containment to keep it separated from other things Importance of contamination reduce prevent microbes Not a preservation technique but a prevention technique Some MAP and smart packaging can improve quality Additional layers of packaging serve to protect the primary package and aid in distribution hard to individually load hershey kisses don39t usually shrink wrap fruits and vegetables bc of respiration Secondary packaging protects the primary package and enhances freshness can use wax box to make water resistant be not recyclable Many food products contain the secondary and primary package Tertiary and beyond packages help contain retail units Pallet stacking is critical in shipment Packaging functions to extend shelf life of perishable foods MAP of fresh fruits and vegetables undergoing respiration and generating heat add C02 to keep fresh processed meats replacing 02 with nitrogen no respiration however don39t get rid of all 02 bc completely anaerobic conditions could lead to botulism potato chips puffed up packs use nitrogen to prevent lipid oxidation and prevent chips from being crushed Gas composition can slow deterioration Active packaging can prevent damage due to MAP Metal and glass are the traditional packages in food processing Hermetically sealed cans were the basis of Appert s work first cans Glass containers lacquers are needed to prevent the corrosion of cans use aluminum tin or steel Glass containers impervious to odors and microbes easy to fill chemically inert transparent to microwaves reusable and recyclable easy to mold into shapes and colors add value rigid strong Disadv Weight can fracture variable dimensions can be safety hazard Packaging materials must be thoroughly tested to ensure performance must measure entire container chemical test mechanical test Chemical migration resistance to grease scalping pushing stuff out also how much gas can get through Mechanical barrier properties strength heat sealing how readily does it heat seal clarity NVTR gas transmission rates H20 vapor transition rate resistance of films to acids alkalies amp other solvents glass impervious to odors gases microbes suitable for heat process when sealedtransparent to microwave rigid strong valuable However glass is heavy and can break safety hazard It39s a blast video 1 what are the three categories of causes of food spoilage Action of naturally occurring microorganism Microbes mold bacteria yeasts Enzyme activity Environmental agents oxygen light other gases 2 what is the temperature danger zone and what are the temperatures associated with it 40 60C bacteria grow very well 3 what 2 kinds of heat are used to quotregeneratequot blast frozen food Dry heat and steam heat 4 How long does the blast chiller take to bring food from 90C to 3C How long does it take to go from 90C to 18C 40 minutes 90 to 18 no more than four hours 5 Slow freezing produces what kind of ice crystals what type of crystals does blast freezing create why are the crystals formed by blast freezing far better as far as quality then those produced by slow freezing Macro Crystals Micro crystals less damage to tissue structure of food food keeps its consistency color and texture 6 what is freezer burn Freezing growing of water crystals water seeps out of cell structure cell structure no longer in tact 7 Normal freezing can cause freezer burn while blast freezing does not T or F True Blast chilling reduces food chilling to a safe level as quickly as possible Food Processing Technology Chapter 2 5a DISCUSSION QUESTIONS What types of packaging are suitable for butter cheese frozen foods and UHT sterilized foods What is reason for these differences Butter and cheese foil tube bagwrap pot trayoverwrap film allow air ow Frozen Foods wax paper box something impermeable to moisture UHT sterilized foods Bottle pot tub film Reasons for differences Package strength required ratio of package weight to product weight marketing properties consumer convenience cost and disposal options environmental factors that cause physical or chemical deterioration of foods oxygen UV light moisture vapor temperature microbes etc shelf life of food grease resistance protect from contamination What are the requirements for shipping containers Containment to hold the contents and keep them secure for the consumer Without leakage transport and distribution Be compatible with food product doesn t cause chemical changes to food and doesn t get crushed if stacked Protect from physical chemical and microbial contaminationdeterioration such as being crushed shakingmoving in package temperature moisture light oxidation carbon dioxide inform the carrier about the destination and any special handling or storage requirements Convenient including easy opening dispensing and resealing being suitable for easy disposal recycling or reuse Low cost What are the types of lacquer are used in tin cans for beer Why are they necessary Lacquers prevent interactions between the can and the food corrosion and chemical changes that may result from package TYPES Epoxy phenolic compounds are Widely used They are resistant to acids and have good heat resistance and exibility They are used for canned meat fish fruit pasta vegetables beer and other beverages Vinyl compounds vinyl chloridevinyl acetate copolymers have good adhesion and exibility and are resistant to acids and alkalis but do not Withstand high temperatures used in heat sterilization They are used for canned beers Wines fruit juices and carbonated beverages and as a clear exterior coating Butadiene lacquers prevent discoloration and have high heat resistance They are used for beer and soft drinks and with vegetables if they have added Zinc oxide Epoxy amine lacquers are expensive but have good adhesion heat and abrasion resistance exibility and no off avors They are used for beers soft drinks dairy products fish and meats Alkyd lacquers are low cost and used externally as a varnish over inks They are not used internally due to off avor problems Oleoresinous lacquers are low cost general purpose gold colored coatings used for beers fruit drinks and vegetables They can incorporate Zinc oxide for use with beans vegetables soups meats and other sulphur containing foods How does the shape of a glass container affect its relative strength Describe a product type for each type of container Relative strengths of glass containers cylindrical 10 mayonnaise jar Elliptical 21 5 wine bottle Square with round corners 25 pickle jar square with sharp corners 1 coffee jar What advantages do flexible lms have What are their main limitations 732 Advantages A range of barrier properties against moisture and gases and a range of wet and dry tensile and impact strengths Heat sealable to prevent leakage contents the ability to laminate to paper aluminum or other plastics Suitable for high speed filling and ease of handling and printing Convenient for the manufacturer retailer and consumer Add little weight to the product and fit closely to the shape of the food thereby wasting little space during storage and distribution Relatively low cost Disadv Can be complicated large number of possible combinations of polymer eX polyester polyamide polyethylene polypropylene and treatment stretch the film add stabilizers pigments antioxidants and slip agents Creates ranges in mechanical optical and thermal properties Can be eXpensive very difficult to recycle also involved in scalping and migration pthalecs andor BPA Spring 2011 FOOD SCIENCE 4010 Lecture 23 Packaging MAP developments printing and environment PRJNIPLEamp Microwavable containers must be designed to withstand storage and preparation conditions Meet all requirements of other packages contain the product prevent from recontamination Be able to withstand freezing for most applications don39t want weep puddle at bottom of package Transparent to microwaves not foil several plastics and nylons are used can39t get too hot Susceptors Microwave Susceptors are used to provide additional thermal heating on the outside of food articles that are heated in a Microwave Oven Microwave Susceptors are typically aluminum metallized Polyester PET sheets Combined packaging systems provide multiple functions Challenges recycling excess packaging compatibility Different materials for primary touches food secondary packages contains primary package etc Shrink wrapping of boxes on a pallet to keep them together Bag in the box for wine and olive oil to keep from oxidation bag collapses in on itself no air can get in Combined packages also for MAP Looking for packages that can serve more than one function want it to be convenient want ease of distribution New packaging materials are evaluated for possible migration of compounds into the product and scalping of flavor components Migration compund leaves package and goes into food doesn39t happen w glass bc inert and scalping package pulls chem cmpnds out of food can scalplose nutrients and flavors Purpose of a package Effect of environmental conditions on migration and scalping Source reduction and recycling are the primary ways to reduce packaging Source reduction is reducing the amount of packaging like thinner cans or reduc ing secondary packaging Recycling means reuse of a product for other materials but must have a usedemand for the recycled materials Packaging is a major contributor to energy consumption and production of greenhouse gasses Big contributor to energy consumption Not as big a contributor to greenhouse gases Causes pollution Note effects of transport Food Processing Technology Chapter 2 5b DISCUSSION QUESTIONS What are the similarities and differences in CAP EMA GEP VP amp VSP Controlled atmosphere packaging CAP continuous monitoring and control of gas composition in bulk containers like on a ship Equilibrium modified atmosphere EMA gas flushing of packs of fresh fruits or vegetables or sealing Without gas modification to allow a gas equilibrium to be established as a result of respiration cut lettuce Gas exchange preserved GEP replacing air with a series of gases in quick succession to inhibit enzymes or kill microbes before packing in nitrogen Vacuum packaging VP The removal of the majority of air from a pack that has low oxygen permeability with subsequent changes in gas composition due to metabolic activities of the product or microbes Vacuum skin packaging VSP same as shrink wrap placing a softened film over the product and applying a vacuum to form a skin What are the optimal MAP conditions for papaya spinach and lime Why is there a difference Papaya tolerance max C02 5 minimum Oxygen 2 Optimum C02 5 8 optimum Oxygen 2 5 Recommended storage temp IO ISC Spinach tolerance max C02 15 max Oxygen NA optimum C02 10 20 max Oxygen air recommended storage temp 0 5C Lime Tolerance of C02 and 02 not listed Optimum C02 0 10 Optimum 02 5 10 Optimum storage temp 10 1 5C The atmosphere is not constant in all MAP products and will change according to The permeability of the packaging material Microbial activity respiration by the food In fresh fruits and vegetables want to minimize respiration and senescence wo changes in quality to food Some are moreless tolerant to C0202 Can t store these together different temps sometimes do compromise temps chilling injury if stored below optimal storage temp especially important w tropical fruits What is nanotechnology How will it change food packaging What are some concerns over nanotechnology 757 Nanotechnology is the characterization and manipulation of materials in the range of 1 100nm 10 9 It can improve the inherent problems of natural polymers including low mechanical strength and poor moisture barrier properties It has potential applications in food packaging to improve the properties of existing materials or to develop new materials that have unique properties Polymerinorganic nanocomposites together with organoclay reinforcement of bipolymers can improve mechanical barrier and thermal properties Polymersilicate nanocomposites are better than normal filters higher heat resistance increased exibility lower gas permeability dimensional stability and good surface appearance DISADV section is talking about thin layer of silicon oxide used to coat packaging May not be an effective moisture barrier and its gas barrier properties may decrease gas barrier properties can decrease with increasing relative humidity can get some of nano particles in plastic in food may be toxic Rank order the most energy requiring packaging materials from most to least aluminum glass paperboard PET resin polypropylene and shrinkwrap Give an example of each 1Aluminum soda can 2 Shrinkwrap cigarette package fuits 3 PET resin frozen dinner coke bottle 4 Polypropylene ziplock bag 5 Paperboard frozen pizza box 6 glass Wine bottle On What factors does recycling of plastics based More inert better absorb smaller amounts of contaminants from foods they contain PET and PVC are more inert than polystyrene and HDPE HoweVer the level of contaminants can be controlled off line using high performance liquid chromatography HPLC or gas chromatography GC laboratory equipment or on line sniffing deVices Spring 2011 FOOD SCIENCE 4010 Lecture 24 Filling and Sealing of Containers PR1NIPLES Container filling is carefully controlled by weight gross weight is everything in package net weight is what food is Difference between net weight just food and gross weight everything in package Gravity pressure and vacuum filling all these types can come into play Can also be filled by volume like saltines or number of items through a photosensor mampms Seam evaluation is a critical test in canned products diameter height length thickness hooks See operations in fig 266 on pg 791 Must measure body hook etc Is this part of QC or QA Minimally processed no heat not a lot of pressure cutting slicing MAP looks more fresh foods require sophisticated packaging systems more perishable more likely to be unsafe looks healthier nutrients not lost as rapidly fruits and vegetables lose vit C rapidly More important than ever for package to keep out contaminants including microbes Hurdle technology use several preservation techniques refrigeration pH change etc can keep fresh for longer period of time Minimally processed generally implies no heat or other microbial kill step Highly perishable and can become a safety hazard Produced to provide the consumer with fresh flavor Other hurdle techniques may be incorporated like antibiotics scavengers etc Tamper resistant packaging is important in protecting the consumer Tylenol scare in 1982 pple who were dying bc of cyanide poisoning some person was going to supermarket and putting cyanide in pills then putting them back together Tamper proof packaging came in Metal detection is a critical control point heat or kill steps Don t want metal in product Could have dropped in product from machinery bolt nut or shavings problem only occurs before sealing Can use magnets or other methods of metal contamination Must detect the metal and be able to remove the offending container Heat is most critical control points metal can be one too Food Processing Technology Chapter 26 DISCUSSION QUESTIONS Why is headspace essential in canned products A headspace is needed above the food to form a partial vacuum This reduces pressure changes inside the container during processing and oxidative deterioration of the product during storage Must be careful not to entrap air add sauces and gravy before solid particles What products use pressure seals What are some examples of these types of seals Pressure seals are mostly used for carbonated beverages They include Screw in screw out or screw on screw off external screw Crimp on lever off crimp on screw off or crimp on pull off roll on or spin on where the closure is pressed against the finish to form a thread screw off also roll on pilfer proof ROPP closures Examples include cork or injection molded polyethylene stoppers or screw caps crown caps pressed tinplate lined with polyvinyl chloride or aluminum roll on screw caps How does horizontal form fill seal equipment work 795 In the HFFS system products are pushed into the tube of film as it is being formed The traverse seals are made by rotary sealers which also separate the packs A modification of this equipment is used to fill laminated cartons aseptically A web of material is sterilized in a bath of hydrogen peroxide and formed into a vertical tube An internal tube vaporizes any remaining hydrogen peroxide The tube is then filled sealed through the product shaped into a carton and top sealed The ears on the base of the carton are folded flat and sealed into place What is the pre formed tray or bag system for MAP What types of products use this system Using HDPE Highdensity polyethylene PET Polyethylene Terephthalate or HIPS High impact polystyrene trays or preformed plastic bags vacuum with gas ushing Meat fish nuts prepared meals What are the advantages and disadvantages of pressure sensitive labels and in mould labels Would either of these be appropriate for the products manufactured by Whistlestop Foods Pressure sensitive labels self adhesive labels that are precoated with adhesive mounted on a roll of release paper and removed before application advantage ln mold labels involves thermoforming the container and labeling at the same time advantage A printed paper label that has a heat activated coating on the reverse side is placed in the thermoforming mold before the parison A hollow plastic tube from which a bottle or other hollow object is is inserted When air is injected to blow the package shape the heat activates the coating A combination of heat air pressure and the cold surface of the mold secures the label to the pack and sets the adhesive The label also contributes to the strength of the pack and reduces polymer use by 10 15 advantage Fruit leather pressure sensitive easy to apply to plastic bags Plastic cups more sturdy ln mold labels Spring 2011 FOOD SCIENCE 4010 Lecture 25 Materials handling and waste management PR1NIPLEamp A systems approach views the steps in handling processing and distribution in context of the entire process rather than as individual operations optimize system rather than individual steps improvement in one step can actually slow down process Water treatment in the plant is critical as water plays many important roles in the food industry hard vs soft water hard water has minerals soft water doesn39t amount of removable calcium carbonate salt measures it hardness affects pH balance more hardness less sanitizing properties Looking at the forest not the individual trees whole is greater than the sum of its parts Optimizing individual steps does not necessarily optimize the system can slow down whole process if optimize steps HACCP is a broader picture and type of systems approach Few substances are as effective although some use bromine and others ozonation Chloronation kills microbes prevents infections by parasites chlorine can combine with other products to become toxic must use proper amt Biological Oxygen Demand is an important measure for assessing wastewater contamination related to amount of dissolved and suspended solids with dissolved solids bacteria can break particles down inot waste they need oxygen Related to the amount of dissolved and suspended solids Large amounts of dissolved solids bacteria breaks down the waste BOD is the measure of the 02 is needed to clean up the waste if the amount of dissolved 02 is not sufficient to meet BOD then the water will go anaerobic if water goes anaerobic kill animals in water fish Food plant sanitation is a responsibility of the Quality Department Sanitation must be an independent function Thorough inspection followed by an inspection report until the QC Manager signs off on the sanitation report the plant cannot operate usu thorough inspection followed by inspection report needs to be signed off by plant manager for plant to operate Hard water has minerals soft water doesn39t Mineral content has sanitation role altered or treated by ion exchange affects pH balance changes process prevents clear beverages from being formed Can reduce water use in certain processes by recycling Timers wash nozzles used water costs money to use or fix contents Food Processing Technology Chapter 2 7 DISCUSSION QUESTIONS What are the advantages of correct materials handling techniques Savings in storage and operating space Better stock control Improved working conditions improved product quality lower risk of accidents reduced processing time lower costs of production less wastage of materials and operating time How do the solubility characteristics ease of removal and changes induced by heating affect sugar fat protein and salts on equipment surfaces Sugar is water insoluble easy to remove and can become difficult to clean if heated because of caramelization Fat is water soluble and alkali soluble difficult to remove and can become more difficult to clean if heated because of polymerization Protein is water insoluble alkali soluble and acid soluble It is very difficult to remove and can become more difficult to clean if heated because of denaturation Monovalent salts NaCl are water soluble and acid soluble easy to remove and do not become more difficult to clean if heated Polyvalent calcium chloride calcium manganese etc salts are water insoluble and acid soluble difficult to remove and can become more difficult to clean if heated because of interactions with other constituents What functions can trucks perform that pneumatic equipment cannot and vice versa 813 1 5 Pneumatic conveyors consist of a system of pipes through which powders or small particulate foods are suspended in recirculated air and transported air velocity is critical too low food settling pipe blockage too high damage to food and pipe cannot be overloaded have few moving parts low maintenance costs and require only a supply of high velocity air Trucks Direction of movement horizontal only intermittent non continuous frequency locations served unlimited area height working height or floor level can carry packed bulk solid liquid materials service temporary Pneumatic equipment Direction of movement vertical up vertical down incline up incline down or horizontal frequency continuous location served point or path height overhead working height or underfloor materials bulk solid and liquid service permanent How do the volumes and composition of processing wastes differ between the dairy beef and vegetable industries How do these differences affect the way the waste is treated Meat packing Volume liters per unit 9000 36300 BOD biological oxidation demand 600 1600 mg1 1 suspended solids 400 720 mg1 1 Milk processing Volume liters per unit 12 2 3 BOD biological oxidation demand 20 650 mg1 1 suspended solids 30 360 mg1 1 Vegetable products Volume liters per unit 90 1260 BOD biological oxidation demand 500 11000 mg1 1 suspended solids 30 4000 mg1 1 Fruit and vegetable processing ef uents have high concentrations of sugars starch and solid matter such as peelings whereas meat and dairy processing ef uents contain a higher proportion of fats and proteins Different disposal methods Who generally treats processing ef uents On what does the cost depend What types of compounds have the biggest polluting potential In large processing plants or those located in unpopulated areas ef uent treatment may be carried out on site in purpose built facilities or ef uents are pretreated to remove solids fats and greases or by pH adjustment before treatment by municipal authorities or private water utilities Solid wastes packaging and office waste materials are collected in some countries by municipal authorities and in others by private waste management and recycling companies They are usually disposed of in landfills but recently more effort has been made to recyclereuse The cost of ef uent treatment is based on a combination of the volume of ef uent and its polluting potential as measured by chemical oxidation demand COD or biological oxidation demand BOD High concentrations of sugars starches and oils have very high polluting potential CODs from 500 4000 mg 1 1 compared with domestic sewage at 200 500 mg 1 1 because as microbes utilize these materials they remove dissolved 02 from water which may kill fish and aquatic plants Spring 2011 FOOD SCIENCE 4010 Lecture 26 Process control PR1NIPLEamp Raw materials are the primary ingredients for processed foods Each processed food is made up of ingredients that are listed on the label in order from most prevalent to least A main ingredient that identifies the food is called a raw material flour wheat wine grapes Sensors measure a process variable and properly sequence events feed us information give us better control A sensor is an inline device that helps us measure the efficiency of the process or quality of a product pH probes thermometers etc can be for chemicals or microbes Can help determine if a process is in control meets standards Can determine when to add an ingredient or start an operation Must be careful not to over rely on sensors sometimes a sesor is wrong so you like to have a backup system Artificial intelligence is used to control processing equipment Neural networks are a form of artificial intelligence used most in food industry more complex process more you can do and screw up Neural networks try to quotlearnquot things like the human brain They learn by making connections makes predictions basically alga rhythms Applied to control extrusion conditions proper times and temps etc Extrusion is a complex process product conditions product quality and added materials are variable Distribution involves everything that happens to a food from the time it leaves the processing facility to the consumer concerned with truck vibrations truck heating via sun truck docks Food scientists generally don t worry too much about distribution Perishable products must be monitored after they leave processing plant from field to final destination Closed display cases can be carefully monitored in supermarket open display cases make it difficult to monitor temperature Open cases like those for fresh produce have many problems same for milk an cheeses etc Trucks monitor airflow with perishable products Food quality should be evaluated at retail to see the product as the consumer sees it we tend to take the best product to evaluate shelf life biased New products are evaluated usually after pilot process not in main plant Pilot processing generally is a best case scenario better control over smaller equipment than in big plant Smaller errors are less likely to show up in pilot plant Even when you do a shelf life study it is generally under optimal conditions Few investigators simulate shipping and handling Should periodically take samples from retail stores and compare results of product with simulated storage Food Processing Technology Chapter 2 7 DISCUSSION QUESTIONS What is process control and Why is it important Process control activities involved in ensuring aprocess is predictable stable and consistently operating at the target level of performance with only normal variation fighting microbes reduce variability if make something too good one day consumer expectation will be changed The purpose of process control is to reduce the variability in final products so that legislative requirements especially safety and consumers expectations of product quality and safety are met It also aims to reduce waste and production costs by improving the efficiency of processing We use computers electricity or manual labor for quality control What types of sensors can be used for packaging film thickness or high risk foods 822 High risk foods immunosensors biosensors Packaging film thickness near infared detector Sensors for toxins safety microbes flavor texture color What is sequence control How does it work Give an example of a process that could use sequence control 828 The second requirement of process controllers is the proper sequencing of actions in a process In microprocessor control the control loops in a system use sequencing control Where the completion of one operation signals the controller to start the operation with or Without a time delay eX changing the supply silo for a sugar ingredient How do centralized control systems differ from integrated control systems 832 Centralized systems have a mainframe computer in centralized control room which monitors and controls this process in specified zones The central computer checks the position of valves uid levels flowrates densities and temperature in the plant and if a fault occurs it sounds an alarm and produces a printout of the faulty equipment for operators in the control room Major disadvantage unless equal capacity computer on standby problem W central computer causes entire plant to shut down Integrated control systems do not have this problem and are more common Integrated control systems distributed control systems in different sections of a factory or in different factories are linked to form a larger management information system A central computer has mass data storage sophisticated data manipulation and communication with other management computers this allows it to be used for other functions including marketing quality assurance and plant maintenance in addition to process control Each distributed control system is independent and if one component fails the others maintain full control of their process areas What are the five temperature zones for the storage of foods Ambient Whatever temperature happens to be semi ambient 10C chill 5C chilled 0C and frozen 25C Also need to consider wet vs dry ethylene producers vs ethylene sensors Spring 2011 FOOD SCIENCE 4010 Lecture 27 Food Processing Challenges and the Future PR1NIPLEamp The objectives of food processing are to preserve foods spoilage and safety remove toxins and provide consumers with safe wholesome and enjoyable foods with a reasonable shelf life Preserve foods Provide consumers with safe wholesome even if you knew everything that was in it you39d still buy it and enjoyable foods Reasonable shelf life maintain necessary nutrients make money for company How does this relate to the objectives in the first part of the semester Heating freezing and drying are the most widely used preservation technologies Primary types of processes that we considered Most important aspect of food preservation is to kill microbes or keep them from growing Canning is the process that involves sterilizing a product primarily by heat kills spoilage and pathogenic microbes Freezing turns water into ice thus depriving microbes of the water they need to grow Emerging food processes attempt to preserve foods while decreasing damage incurred by more widely known techniques Microwave heating ohmic heating high pressure processing and pulsed electric fields All are expensive All reduce losses in flavor and nutrition Most expensive part of canned food can Food processing can make an important contribution to health and wellness of consumers Public opinion suggests that processing decreases the health and wellness of foods Health and wellness is about what you choose to eat not whether it is processed or not The success or failure of any food product is decided by the consumer To be successful products must sell must be liked by consumer Sensory quality color flavor texture Hidden quality safety and nutrition Image characteristics marketing Microbial ecology studying growth conditions of microbes what are some misconceptions about canned foods despite their benefits Preservatives and low nutritional value what happens in the rotofeeder The ends of the cans are attached in two steps Seamed then stacked in layers when did the history of the can begin who came up with the idea of canned food what helped kill the germs Late 1700s 1795 with napoleon bonaparte nicholas apert cooked food inside champagne bottle put food water food into container water bath killed germs what was added to the water bath to improve the taste of food in the cans How did it help Sodium chloride raising boiling point of water reduce cooking time what did the north have that the south lacked what were popular items for soldiers when did the canning industry begin to expand Canned food canned meats and condensed milk after the american civil war safer better tasting who was the first person to introduce canned spaghetti to the American public Hector Boiardi what did the FDA ban in the manufacturing of cans Lead solder HYPERLINK quothttponlinelibrarywileycomdoil 01111j1541 433 7 201 0001 27xpdfquot http Zonlinelibrarywileycomfdoiz101 1 1 1j1 541 4337201100127Xpdf DISCUSSION QUESTIONS How do acidification and lowering water activity function to preserve foods Why are additives essential to a safe bountiful food supply What is the most Widely used group of food additives Provide examples of each and their functional properties How can we manage food waste more effectively How can food scientists contribute to solving the diet and disease challenge What are the strengths weaknesses opportunities and threats associated with the application of biotechnology to foods


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