FSN 230 Midterm 2

**look up table on page 89

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Vacuum in Cans

**foods are packed under vacuum for several reasons: 1. to minimize swelling due to pressure changes 2. to remove O2 from headspace 3. to prevent buckling during retort process How is a vacuum obtained in canned foods? 1. add hot food to the container and seal 2. use cold product but pass through a steam box uncovered 3. pull a vacuum mechanically. limitations 4. steam jet vacuum it is called steam flow vacuum

Heat

**pasteurization- low energy thermal processing**, destroy all pathogenic MOs in specific products, extending the shelf life by lowering the number of spoilage organisms, not a sterile product and subject to spoilage blanching-heat treatment- mild heat treatment, used in fruits and veggies, to inactivate enzymes, may destroy some MOs pathogens in milk are different than pathogens in juice-target thee specific pathogens when pasteurizing.

Danger Zone For Foods

*40-140F* 4.4-0C-keep foods out of danger zone.

See pg 92 for heat transfer ex

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Major causes for food spoilage

1) microbial-very fast 2) physical 3)chemical main goal of food press is to stop MO spoilage and minimize physical and chemical changes from occurring. aside from prevention of food borne illness food science is concerned with preserving he oversupply of food for year round consumption.

Canning: Typical Process

1) pretreatment of product: clean cut put slice dice inspect 2) blanching of product:steam or hot water 3) filling and creation of can vacuum: vacuum-->removes O2 from the can headspace, minimizes swelling of the can due to pressure changes, prevents collapsing of the can during processing 4) sealing the can: a hermetic seal is formed, environment inside the can is anaerobic. 5) processing the cans: in a retort, process at 250F at 15psi steam for up to 2 hours 6)cool the cans: in potable water until the pressure inside is equal to the pressure outside 7) pack cans in cases, want temp to remain between 50 and 85F (transportation-different pressure around the world)

Factors accelerating fat oxidation

1-heat, the higher the temp a fat is at the faster the rate of oxidation. 2- certain wavelengths of light, uv or near uv light accelerates oxidation of fats. 3- high energy radiation- cathode beta and gamma rays 4-certain metal ions, cu, mg, ni, fe

Major classes of food preservation

1-physical-remove constituent- dehydration 2-chemical-add constituent- preservatives/antioxidants 3-biological-action of some organism growing in or on food-fermentation 4-add heat to food- cooking canning 5- removal of heat from food-refigeration 6-combo of above methods

Clostridium Botulinum

20-30 cases/year 2-5 deaths. Spores are very heat resistant.Wont grow in acid foods. Spores cant germinate in acid environment. Most cases involve home processed foods. Food processing industry in the US has an excellent record.

Salmonellosis

2000+ species, 20000+ cases/year. NON SPORE FORMING, rod shaped, motile, facultative anaerobe, 7-14 day incubation period. Not heat resistant. Optimum growth 37 C-body temp. Usually from shellfish, eggs, milk, raw and uncooked meat. People become carriers. The carrier stage last more than 12 weeks (breathing, mucous). Occurs when food is cooked improperly and held at warm temps. 140 for 5 min =90% destroyed. 140 for 10=99%. 140 for 15=99.9%. If some survive the heating they will grow in room temp. Pets may have salmonellosis, may become carriers.

high and low acid food

4.6

Heat

Degrees of preservation -Sterilization: complete destruction of MOs, requires at least 250F, destruction of spores, time is important -Commercial Sterilization: all pathogenic and toxin forming organisms have been destroyed, may contain viable spores that can not grow under normal condition.

Food Preservation Basic preservation techniques

Drying- in the method the Aw is lowered by removing water and the microbial growth is prevented Freezing- the water is crystallized thus is unavailable for MO growth Fridge- slows down MO growth Heat Sterilization (commercial)- destruction of veggies microorganisms, spores, especially the pathogenic MOs occur by using heat. complete heat sterilization- almond soy milks, high temp destroys everything freezing dont destroy microbes

Enzyme Reactions

Enzymes- biological compounds that are produced by living things and catalyze chemical runs. E+S->ES, ES=R->P+E

Food Safety

Food Safety Hazards- chemical, microbiological, physical (foreign materials). Cross-contamination- transport of harmful substances to food by:hands touch raw foods, surfaces, drip fluids on cooked or ready to eat foods.

Food Intoxication

Happens when--> microorganisms in infected food grow, MO in food produce toxin, the person eats food with toxin in it, peson gets ill from the act of toxins. Onset of symptoms is quick (2-8 hours) ex: staphylococcus aureus, clostridium botolinum, clostriduiumperfringens.

Food Safety

High Risk foods (sensitive foods)- High protein (fish milk) high moisture, low acid (veggies). meat dairy eggs are high protein, sensitive and spoil quickly have to deal with them quickly. Sour cream yogurt- acidic, can live in car for a while

Food Safety and Sanitation Cont.

In general- avoid the temp danger zone (40-140) don't park in loading zones (or you will get a ticket) heat to 140 cool to 40. frozen food should be kept at 0 or below. Cutting boards ar notorious for transmitting bacteria. Wash after use. Wash all raw foods before processing. Always thaw food in refrigerator or in cold, running water. Use first in first out rule. Cool hot foods quickly. When in doubt, throw it out

Microbial Spoilage of Foods cont.

Microbial food spoilage (or food spoilage in general) can be detected organoleptically. See smell taste or feel. Remember the growth requirements of MOs, both intrinsic and extrinsic, determine what foods they are going to spoil.

Food Preservation Basic preservation techniques

Pasteurization- inactivates many microorganisms using heat- aim for certain pathogens Fermentation- lowers pH inhibits MO growth Pickling salting sugaring- by lowering PH and o rAw inhibits MO growth

Food Poisoning

Pathogenic MO's cause food borne illness Food Poisoning is a common term used to describe 2 types of food caused sickness- Food infection and Food intoxication

non enzymatic non oxidative chemical rxns in foods

Protein aggregation- it is the bonding of protein chains to form a new network of protein. since the protein network is closer the water that is loosely held b the protein is squeezed out and causes drip loss in frozen foods-defrosting. When it happens the tissue becomes tough and dry. Happens in low fat fish during frozen storage. If the fish is held at temp lower than -22F the difference between the fresh and frozen fish is undetectable. water between the cells is squeezed out

Food Safety and Sanitation Cont.

Staphylococcus- people may be carriers of Staph on or in the nose, throat, and hands. 25% of the cases are caused by poor personal hygiene. Cross contamination by unwashed hands and improper sanitizing often implicated. May be food to food transmission. Salmonella- 1/3-1/2 of all chicken have salmonella on them. people may become carrier for over 12 weeks.

Food Infection

The living microorganisms must be PRESENT in the food. The person involved must consume very high numbers of the living microorganism. The living microorganism in the gut of the person involved causes the illness 1. Salmonella 2. shigella 3. vibrio 4. trichinella 5. esherichia coli 6. yersinia 7. capylobacter and others (live in microbes-go into guts & attack) more common

Heat Transfer**

Thermal death curves log equation D value: time in minutes at a specific temp to reduce the number of microorganisms by one log cycle (D121-3.5 min)-->playing with the time, same temp Z value: the temp required to decrease the time necessary to obtain a one log reduction in cell number to 1/10 of the original value (100 min at 220F kills 90% of microbes and 10 min at 238F also killed 90% of the organisms, the z value is 18F) one log reduction in D value. --> difference in the temp that does the same thing, playing with temp/reducing time

Clostridium Botulinum

This bacteria produces four different types of toxins. Types A B E and F that are harmful to humans. All toxins can be inactivated by boiling for 5 to 10 min ( but at right temp). <1ng of this MOs toxin can be fatal. Usually caused by improperly canned foods (home-made) spore forming, 10-20 outbreaks annually in the US. Almost all of them are from home made canned foods

Selecting Heat Treatment

To pick right treatment: 1) time temp combo required to inactivate the most resistance microbes 2) heat penetration characteristics of the food and container: particle size, consistency, size shape material of the container. time/temp-to get to middle

Hazard Analysis and Critical Control Point (HACCP) System

Types of potential hazards that occur in our food? biological (salmonella) , chemical and physical (bone) . Biological- pose the largest threat to food safety pathogenic MO (bacteria, viruses, parasites, mold, yeast) Chemical- pesticides, chemicals in cleaning supplies, toxic metals, food additives and preservatives (allergic run) Physical- includes materials that do not belong in the food, but through negligence or chance, get in the food. HACCP-used in food production plants mandatory for meat or poultry products and for juice.

Microbial Spoilage of Foods

Why do foods spoil when exposed to MOs? Mos are interested in reproducing themselves. This can be very rapid as fast as doubling in count every 20 min. This geometric progression is unlike enzymatic or oxidative spoilage which is linear because the reagents are fixed. By-products are excreted from the MO cells where they can cause spoilage or perhaps a desired change. Because of the rapid growth of MOs by-products can accumulate quite rapidly. Unlike enzymatic o/r rxns spoilage happens from the by products.

Food Infection

a food infection is caused by the ingestion of sufficiently high umbers of a live pathogenic MO. The pathogen grows in the human body rather than in the food. The onset of symptoms is usually longer than for food intoxication (18-24 hours) Frank pathogens= salmonella, shigella, yersinia-- always considered pathogenic

HACCP

a system to ensure the safety of foods. HACCP is widely accepted and recommended for all aspects of the food industry. 7 steps 1) assess the potential hazard ( from raw materials production of finished products, potential hazard foods, review recipes, flow charts) 2) Determine the Critical Control Points (CCP) where controls are necessary to eliminate or reduce hazards. (put CCPs on flow charts) 3) Est. requirements or parameters to be met at each CCP (based on regulation data etc) 4) est procedure to monitor each CCP 5) est corrective actions should have a deviation occur at a CCP (reheat or throw out) 6) est record-keeping procedures 7) est procedures to monitor or verify the effective of the HACCP plan (lab analysis of samples-microbes or chemical hazards)

Sanitation in the Home

about 88% of all cases of food poisoning can be traced to handling of food at improper temp. Meats, eggs, poultry, and fish should be held at safe holding temp.(below 40 above 140) Use 50 ppm chlorine for sanitizing. For critical areas use 100 ppm available chlorine. Keep trash outside

Heat

adding heat to a substance- raises its temp, expands or contracts the substance, alters the substances electrical properties, increases the pressure exerted by gases

other thermal processing methods

aseptic fill method- employed following HTST or UHT process, machines may operate with an internal sterile environment, heating cooling package formation and filling all performed the same machine under aseptic conditions hot fill hold process-used when making jam, used for high acid low ph foods, temp is 170-190 for 25-30 min, will kill all veggie cells in the food spores are not killed

Heating before or after packaging

before: batch, continuos, hot pack (fill unsterilized containers with sterilized hot product) after-retort

hydrostatic retort

cans flow continuously, uses hydrostatic heat to control pressure, an agitating system, towers go under pressure going up, if you want to go higher than 212 then have to put it under pressure. commercially sterilized-HOT AND COLD WATER< look at pg 94 pic to see diff

heat resistance of microbes

clostridium botulinum- time temp relationship heat kills MOs logarithmically spores are more heat resistant than bacterial cells

Cholera

comes mainly from contaminated water supplies and is endemic in mainland Asia and pacific rim. (natural disaster). The organism causing cholera is vibrio cholerae. Aerobic, rod shaped, motile, transmitted through contaminated drinking water, or through contaminated food that has been washed with contaminated water. Control=boiling the water, or treat the water.

Conduction/Convection

conduction- collision of hot particles with the cooler ones convection-circulation of warm molecules--more effective, requires less time to reach the target temp, heating start out rapidly, a change in structure may cause further hearing to be by conduction longer heating by convection shorter process time

Heat Transfer

destruction of microbes in food is based on a time temp relationship. Pathogenic spore forming bacteria are the target. C bot is the most heat resistant. *Bacillus stearothermaphilus is a nonpathogenic spore former which is even more heat resistant than C bot- set time on this microbe so if you kill it then you have surely killed c bot

Thermal preservation of foods-canning

developments of the metal can include: various and lamination developed for lining. quick opening cans with pull ties, cans which open with a slotted key,pressurized cans for whipped creams, extruded or drawn cans, plastic cans

Enzyme Reactions

enzymes are either- pure protein, proteins with prosthetic groups (co-enzymes) proteins with prosthetic and metal cations. Ranges of enzyme response- all enzymes exhibit a range of response of rate in relation to the factors of control of living processes. Each factor can be described by the minimum, optimum and max conditions that give a change in response. Enzyme activity- slow minimum-most optimum-slow maximum. Enzymes are temp-sensitve and will have both a temp a ph optimum. For most the temp is 60-150F. Mostly inactive at 160-200F. Some enzymes will remain active following exposure to high temps. Others, are active at freezing temp (shelf life)

Enzyme Rxns

enzymes arent a part of the final product, enzymes repeat their chores many times over working to change some substrate. Chemical runs take place when the necessary reactants are present. An energy input is to start the reaction. This energy is called activation energy -boulder over the hill. Importance of enzymes- life depends on enzyme to convert foods or nutrients to a form in which they can be utilized and to carry out cellular functions. Enzymes may also contain or require complex chemicals in order to become functional. These complex chemicals are usually vitamins especially B groups. Some need metal copper.

Food safety and sanitation

every year there are 10-80*10^6 reported cases of food borne illnesses. Impact is about 80 billion $. In general foods spoil from within due to enzyme activity in foods and from without due to the growth of microorganisms on food. *protein rich foods are the most common causes* Salmonella and Staphylococcus food poisoning are the most common

Controlling Enzyme Action

factors in controlling enzyme activity- temp, water content/activity, extremes of PH, chemicals, alteration of substrates, alteration of products, processing control

Heat Transfer

factors that influence the time needed to obtain a complete heat transfer- size and shape of container, physical properties of the product in the container Methods of heating- conduction, convection, radiation, combo

methods of obtaining commercial sterilization

fill, seal, can

Chemical Rxns

food can deteriorate or spoil because of chemical changes NOT due to microbial growth of enzyme catalyzed reactions. This chemical spoilage usually involves one of two mechanisms- non-enzymatic combo with naturally occurring elements (O2) not part of the food-->oxidation of fats. non-enzymatic none oxidative combo of compounds found within the food-->maillard run.

Aseptic Packaging

food is sterilized outside the container, placed into a sterile container, sealed under aseptic conditions, paper and plastic materials for packaging, most suitable for liquid based food products. completely sterilized, juices soy milk

The preservation of food

food preservation- the near elimination or slowing down of changes in foods due to physical chemical or biological agents or causes. 2 common principles- 1) prevent or delay the growth of microbes on or in the food 2) prevent or delay self degradation of the food.

Staphylococcus Auerus

found in human skin and mucus membrane. If touch nose then work on food-contamination. Toxin produced is not as fatal as botulinum toxin. Toxin is heat stable, can survive normal boiling procedure. Outbreaks=hand made salads, cole slaw, cold sliced ham, vacuum packed bacons. Produces 5 different toxins, (toxin B must be heated to 121 C for 16 min to denature) Growth (most strains are able to grow well in 10% in NaCl, some capable to grow in 20% NaCl) This property is used for selective isolation of the MO. READ SYMPTOMS IN BOOK

Conduction/convection

heating starts as conduction, a change in food makes it into convection, foods containing large pieces of meat, as the juices are released heating switches to convection

Selecting Heat treatment

high heat- destroy all microbes, inactivate enzymes, effects food quality-color, flavor, texture, nutritional value dont want to use high heat, have to choose between destroying microbes or losing nutrients (destroy**) you can always add back nutrients, need to have time temp relationship in mind-very important

other thermal processing methods

high temp-short time process not suitable for large discrete particle foods. because the time required for heat to penetrate to the center of the food is long, applied only to liquids and purees, uses temps of 280-300F for 15-45 sec, ma be referred to as Ultra High temps may also use culinary steam to heat the product quickly, it kills all the bacteria and their spores and the steam added is removed, the product is then filled into a completely sterile packaging and sealed

Thermal preservation of foods canning

history- 1800- Nicholas Appert- developed canning 1810- Durand metal can 1819- 1st canning factory Steam heating 1900- manufacturing and sealing of cans done by machines

Food Preservation

in general foods spoil either due to enzyme activity or the growth of MOs. non of the methods alone result in product being preserved. three main ones-freezing, canning, dehydration

Heat

in physics- transfer of energy from one part of a substance to another because of a difference in temperature heat is energy transit it flows from higher temp to lower the warm and sensation of a substance in contact is measured by temp

Low acid foods

in the US the legal processing required for low acid foods is: exposure to a temp for a period equal to 12 D values for C bot, this decrease any population of C bot through 12 log cycles, provides an adequate safety margin, acid level of food affects the processing times and temps

Sanitation table

look up pg. 66. FDa approved, chemical sanitizers, important b/c 3 diff kinds of all FDA approved. have 3 b/c they behave diff based on food product. know the ph, corrosiveness, rxn to hot water reaction to organic substances in water

non enzymatic non oxidative chemical rxns in foods

many foods are adversely affected by non enzymatic browning while others depend on the type of reaction for color, odor and flavor development. Ex- maple syrup. prunes coffee bread crusts

Liquid in cans

most foods in cans are stored in a kind of liquid, liquids include brine and sugar solutions, sugar/brine solutions for veggie, sugar or syrup solutions for fruits, the liquids speed up the retort process due convection heating,solid packed canned goods heath through conduction heating, and this is slower

non enzymatic non oxidative chemical rxns in food

non enzymatic browning or Maillard Rxn- rxn btwn reducing sugars (containing carbonyl group) and a free amino acid. this reaction results in the formation of complex black and brown compounds that are flavorful. *browning happens faster in food with low to medium moisture content. Caramelization- a reaction to the removal of water from the sugar molecules by heat. this changes the structure of the sugar and results in increasing darkening of color from light to brown to dark. Browning happens faster in foods with low to medium moisture content. expect foods with MC less than 2%

E Coli

opportunistic pathogen. Given opportunity will cause illness. Enteropathogenic v. enterotoxgenic-> (causes problems) strains. Cholera-like gastroenteritis. Produce "shigotoxin" and e coli with shigella genes (bread of 2 microbes). Incubation period 24 hours post ingestion. recover after 24 hours. rarely fatal. Enterotoxigenic strains, toxin is heat-labile ( toxins are produced by microbes, toxins are made of proteins) If you give them opportunity they will become pathogenic.

non-enzymatic oxidation rxn in food

oxidation is usually of concern in relation to the stability of the lipid fraction of the food and whether that lipid fraction contains fatty acids that are saturated or unsaturated. Sat v Unsat.--lipids that contain fatty acids that are completely saturated with hydrogen atoms are called saturated. Lipids that contain fatty acids that contain double bonds between adjacent carbon atoms results in their fatty acids are called unseat-mono and poly unseat. Most concerned w/ oxidation of lipids. usat=lower MP-same amount of carbon atoms, fatty acids and the degree of unsaturation and oxidation add antioxidants. consumers don't like to see BHT or BHA

Sanitary Handling of Foods

personal hygiene: infected individuals should never handle food. Physical cleanliness important. Keep hands covered, fingernails short and clean. Hands should be periodically disinfected. Use gloves when possible. Hands should not touch the nose, mouth, or other orifices and bodily parts. No smoking, drinking, or eating on work areas. No pets or animals in food areas. Sneezing and coughing should be confirmed to a handkerchief. Hands should be rewashed. Foods should be inspected for wholesomeness. PERSONAL HYGIENE MOST IMPORTANT

still retort

product placed on a container and heated in a steam environment without agitation, temp above 250 may burn the product, time of heating is usually 30-45 min.

Major types of enzymes

proteases and peptidases-breakdown or splitting of proteins into smaller units. Oxidases- chemical combo of some components of the food with oxygen. Lipases- breakdown or splitting of fats and oils into glycerol and fatty acids. Phospholipids- the deterioration of phospholipids (lecithin) leading to deterioration and discoloration in foods. Carbohydrases- breakdown or splitting of carbs into smaller units

Food Processing Applications of Enzymes

proteolytic enzymes are used for tenderization of meat (bromelin, papain, ficin from plants) Flavoring-protein hydrolysates are made using proteases (flavor enhancers) Lipase activity in the production of cheese (flavor development in blue cheese) Saccrification activity in brewing industry (conversion of starch to fermentable sugars by maltose) Clearing of juice- use of pectinases.

E Coli Cont.

rod shaped, motile, non spore forming, facultative anaerobe, mesophile with optimum temp at 37C range of -2 +50 C. strain 0157:H7 causes severe hemorrhagic colitis-fatal. Illness associated with eating hamburgers. Associated with contaminated water, improperly/unpasteurized juice, milk, contaminated food. all comes from feces in animals. Hemolytic uremic syndrome-fever bruising, fatigue, short breath, body swelling, jaundice-devlops 7-10 days after initial diarrhea. Kidney failure in children. Children under 10 most likely to get it. Can lead to excessive bleeding, seizures or death.

Food Intoxication

the living microorganism grows IN THE FOOD and produces some metabolic end product (toxin). The person involved must consume the food that contains the toxin. The microorganism does not have to be present within the person. The person reacts to toxin and becomes ill. 1. staphylococcus 2. clostridium botulinum 3. c. perfinges 4. aspergilus flavus 5. bacillus cereus. Doesnt matter if they're alive just that they made toxin. Can be fatal

agitating retort

the product is agitated during cooking, allows the use of high temp, convection heating, reduce the time necessary to reach the final temp, cooking time is usually 10-20% of still retorts agitation makes conduction-->convection

Radiation

transfer of energy in the form of electromagnetic waves, fastest method of heat transfer, transfers heat directly from the radiant heat source (broiler plate) to the food. The contact surface between the heat source and food reduces the amount of heat

saturated v unsat fatty acids

unsat fatty acids having a given # of carbon atoms have a lower melting point compared to the equivalent saturated form of the fatty acids when a lipid is made up of many unsat fatty acids it will be liquid (oil) at room temp when a lipid is made up of many sat fatty acids it will be solid at room temp fatty acids with more than one unseat group oxidize more readily than fatty acids that contain none or only one double bond

**oxidative rancidity

when fats oxidize the resulting end products are made up of a type of compound called peroxides. These peroxides have flavors and odors that are generally undesirable and are characterized as being linseed oil like, fishy, tallowy. This is oxidative rancidity.-beef and mutton fat will be tallowy in taste. Pork, veggie oils and fish oils will have linseed oil. Hydrolytic rancidity- lipase hydrolyses the fat into short chain fatty acids ex-butyric acid peroxides are what smells