FNH 200 Final memory aid PDF

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LESSON 1Food Science is the application of basic principles of science & engineering to study and acquire new knowledge on physical, chemical and biochemical aspects of food. Canning – Nicholas Appert; French confectioner (1795) Heat processing results in longer shelf life and initiated the ...

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LESSON 1 Food Science is the application of basic principles of science & engineering to study and acquire new knowledge on physical, chemical and biochemical aspects of food. Canning – Nicholas Appert; French confectioner (1795) -Heat processing results in longer shelf life and initiated the canning tech. Freezing – Clarence Birdseye (1900s); -Rapid freezing of fish in extremely low temperatures preserved the quality of fish much better than the convectional freezing methods Controlled Atmosphere (CA) storage -Slow down respiration rate & ripening process (decrease senescence) -Extending storage life (for months) -Exact conditions depend on the type of fruit & variety (e.g. variation of apple) -Fruits aren’t dead when picked, still alive, CA minimizes the amt. of chng. In fruit LESSON 2 Functional Properties of simple carbs -Reactants in non-enzymatic browning 1. Caramelization -Heating sugar alone to high temp (200C), Aroma compounds (caramel, butterscotch flavours) & brown pigments Eg. Caramel candies, toffees; Color used in cola beverages is created by caramelizing sucrose (all sugars can be caramelized) 2. Maillard Browning -Reducing sugar + amino compounds; Reducing sugars contain a “free” OH on the position next to the O in the ring structure; eg glucose, fructose, galactose, lactose; sucrose is a non-reducing sugar -Products of Maillard browning reaction: -Low molecular weight (Intermediate Compounds) (aroma/flavours – both desirable and undesirable), High molec. Weight polymers (melanoidins) (brown-black pigments), eg toast, roasted coffee, potato chips, bread, sunless tanning lotions, when something is burnt/charred; not a browning reaction -Crystallization; Sugars can exist in soluble (syrup) & crystalline states, Crystallized from solution = eg table sugar (sucrose) from sugar cane juice -Viscosity/mouthfeel, Fermented by microorganisms, Antimicrobial agents, Humectancy (water retention) Functional properties of Polysaccharides: -Stabilizers/thickeners/viscosity -Keep compounds, mixtures or solutions from changing state -Act as thickening agents by increasing the viscosity of the continuous phase -Gelling agents (form gels L/S); gelatinization -Fat replacers Fats & Oils -Produce 9 cal/g -Fats are chemically known as triacylglycerols or triglycerides -Triglycerides = triesters of glycerol & fatty acids -Fatty acids: R1,R2,R3; hydrocarbon chains with carboxylic acid (COOH) at 1 end and a methyl group (CH3) at the other end -Ester bonds hold fatty acids (R1-R3) to glycerol, joining the OH groups of glycerol to COOH groups of fatty acids -Most common fatty acids in food TG: C-16, C-18 -Some foods have shorter chain fatty acids (eg coconut oil: C12) -Others also contain longer chain fatty acids (eg fish: C20 & C22) Common Formula of F.A. Y:X (n-Z) Y: # of Carbon X: # of double bonds n: numbering of double bonds from methyl (CH3) end Ω (always n) Z: location # of 1st double bond If C #s are the same the melting point (temp.): Saturated > Trans (across) > MUFA > PUFA -Double bonds – easily oxidized (oxidative rancidity) -PUFA more reactive than MUFA Rancidity – break into smaller molecs that have odors -Improper storage, repeated exposure to high temp. -2 types: Oxidative – double-bond broken and oxygen gets inside (double bonds + O2  products, off-flavours, carcinogenic compounds) -UFA/PUFAs + heat, light O2  hydroperoxides, ketones, OHs, aldehydes Hydrolytic/Lipolytic – links between glycerol and FA broken  releasing free FAs -Lipase enzymes -Triglyceride + lipase  short-chain (free) FAs + glycerol (odorous) Reducing rate of oxidative rancidity: Proper storage & packaging (away from light, oxygen, warm temp) Limiting repeated exposure to high temp Addition of antioxidants (natural & synthetic) Hydrogenation -Saturate the FAs with hydrogen -Also used by the food industry to “harden” liquid oils into semi-solid fats -Trans FA can be generated! Hydrogen atoms are forced into the unsaturated double bonds of the UFA -Raises the fat melting point (MP) -Less prone to oxidize -Newer margarines use blending to achieve the desired solid-liquid ratio and melting properties Trans FAs: lose “kink” originally present in the cis form -“pack closer together” = the texture more semi-solid Trans-fats -Behave like saturated fat -Raise LDL cholesterol  Coronary Heart Disease (CHD) -Labelling required: amount of Trans-fat Functional properties of fats Mouthfeel – lubricant in food Carrier of aroma & flavor -Majority of these compounds are fat-soluble Shortening/tenderizing power High-temperature medium (deep fat frying) Emulsifiers Lecithin - (it’s an emulsifier, it’s also a fat) Emulsions & Emulsifiers O/W or W/O emulsions Elmulsifiers

Lecithin (phospholipid) from egg yolk, soybean oil -2 FAs + phosphoric acid linked to glycerol -Help reduce interfacial tension  form an emulsion -Amphiphilic/amphipathic molecules: -Hydrophilic: water-loving (ie glycerol linked to an organic acid) -Hydrophobic/lipophilic: water-hating or lipid-loving groups (ie FA) Stabilizers (not the same as emulsifiers) -Increase viscosity of the continuous phase -Keep the droplets suspended or dispersed (eg polysaccharides) Proteins Functional properties emulsifiers -Amphiphilic molecules -Reduce interfacial tension (eg egg yolk proteins in mayonnaise) Foams -Trap air bubble & form rigid 3-D structure; when heated or cooled  solid foams -eg meringues, bread, ice cream Gels -Form 3-D structure that can trap water -eg gelatin gels; yogurt; cheese; frankfurters Enzymes: proteins that function as biological catalysts -Promote a chemical reaction that will not occur by itself -Inherent in the foods or added in processing -Desirable or undesirable reactions in foods pH -Determines rate of chemical & enzymatic reactions -Microbial growth/survival in foods -pH value of 4.6 is critical to food industry -borderline between: acid & low-acid foods; most foods are slightly acidic acidic foods (pH 4.6) -eg meat, fish, vegetables total acidity vs. pH -the two concepts are diff. -total acidity (titratable acidity) measures the total acid concentration (grams/liter) pH quantifies H+ concentration (active acidity) LESSON 3 Types of Fat Substitutes 1.Protein based Simplesse; protein is coagulated by heat -create a micro-dispersion: microparticulation -spheres of protein & water are very small; if particle size is too small – watery; too big – chalky -soy, milk (whey) or egg white protein -dispersion perceived as a fluid w/ creaminess & richness of fat -1.3 cal/g 2. Carbohydrate based Maltrin; carb sources: corn, potato, wheat & tapioca; cellulose, starch, gums, maltodextrins and fibre. smooth mouthfeel and bland flavor. maltrin is fully digestible: 4 cal/g (fat=9cal/g); other carb-based fat replacers available range from non-digestible to partially digestible (0-2 cal/g); eg Avicel, Betatrim 3. Fat based sucrose polyester eg Olean AKA Olestra -approved in USA in 1996 (not approved in Canada!) -olestra can withstand high temperatures (eg frying) -rich taste and creamy texture of ordinary fat made primarily from fat -triglycerides are broken down in the body by specific digestive enzymes (lipases). instead of 3 FA chains attached to glycerol, there are 6-8 FA chains attached to a sucrose molecule: sucrose polyester (not metabolized/absorbed by the body; 0 cal/g) -large portions of olestra snacks lead to abdominal cramping or changes in poop. not digested/absorbed – thus fat-soluble vitamins consumed at the time not absorbed. must mention that vitamins A, D, E and K have been added Types of Sugar substitutes -non-caloric (not metabolized by body: 0 cal/g) eg Acesulfame potassium (K), sucralose -non-nutritive or low-calorie (< 4 cal/g) but due to high sweetness  trace amount used eg Aspartame Acesulfame Potassium (K) -200x sweeter than sucrose, heat stable, no contribution to cavities, acceptable daily intake of 15 mg/kg bw/day Sucralose or Splenda -A chlorinated molecule; 3 hydroxyl groups (OH) of the sucrose molecule are replaced by chlorine (Cl); 600x sweeter than sucrose -Heat stable, not metabolized by humans, ADI 9 mg/kg bw/day, no effect in carb metabolism – no increase in blood glucose or insulin levels Aspartame -2 amino acids – phenylalanine & aspartic acid; 180-220x sweeter than sucrose -ADI 40 mg/kg bw/day, ppl suffering from Phenylketonuria (PKU) must avoid, degrades at high temps & overtime; can’t be used on baked goods, degrades into DKP: best before date necessary on products Sugar alcohols -Sorbitol, mannitol, xylitol -Naturally in many fruits; less sweet than sucrose -Cooling sensation, do not promote dental cavities, no major increase in blood glucose or insulin levels; slow absorption – laxative effect (threshold 20-40 g/day) -Partially digested = 1.5-3 cal/g Sensory Perception Foods 1.Appearance factors -Color, size, shape, gloss, consistency, presence of defects 2. Textural factors -Cutting, compression, tensile strength, shearing 3. Flavor factors -Comprises both taste & smell -Water-soluble substance interact with sensory receptors on tongue, detected in mouth; tongue -Fat-soluble & volatile aroma compounds interact w/ receptors in the nose, olfactory region MSG- meaty and vegetable flavours; 5’ Nucleotides – Meaty flavors

-Modify or enhance intensity or quality of taste of another substance eg Maltol (modifies flavors of high carb foods, beverages), MSG, 5’nucleotides -Not regulated as food additive, considered a flavor-enhancing ingredient LESSON 4 Risk/benefit analysis for Aspartame -Metabolized to aspartic acid, phenylalanine = amino acids naturally occurring in proteins -Methanol – toxic at high doses, formed in other foods too oPectin of fruits & veg., juices; 1 cup tomato juice = 6x more methano > 1 cup diet pop -Metabolic pathways – excreted, no effect observed at doses equiv to 5 12-oz cans of beverage -DKP (diketopiperazine) oNot a common food ingredient oWill cause loss of sweetness intensity oNo evidence of carcinogenicity -Health Canada oEvaluated toxicological tests in Lab animals oContinue examining results of clinical studies (humans) oNo evidence to pose a health hazard to consumers except: Metabolic disorder (PKU), Inability to metabolize phenylalanine, labelling is mandatory “contains phenylalanine” Risk/benefit analysis for Nitrites -Benefits: anti microbial (against C. Botulinum – botulism) -Risks: production of nitrosamines (carcinogenic) -Cured meats – minor contribution to total nitrites oTobacco products, beer, fried bacon – much higher oIntrinsic production via nitrates  nitrites in our saliva oNitrates (NO3)– naturally in vegetables; also in our saliva oNitrites (NO2) – converted from nitrates in our saliva oMinimize nitrosamines in cured meats by: ascorbic acid, Naerythorbate (isoascorbate), tocopherol (Vit E) Lactic acid cultures + fermentable sugar ( acidic pH) to control C. botulinum oBenefits outweigh risks Agencies responsible for diff. food-regulations in Canada Federal: Health Canada (HC)/Health Products and Food Branch (HPFB) -Policies & standards for safety & nutrition quality of food oRegulations (food & drug, food additives), standards of identity & composition4food Canadian Food Inspection Agency (CFIA) – enforces standards of HPFB -Inspection of food (processing plants, animal & plant health), grade standards for products, regulations with respect to labelling, packaging advertising (shared with HC) Industry Canada (IC) Provincial – responsible for food produced & sold exclusively within borders -BC Ministries of Health/Agriculture, Food & Fisheries – inspection o provincially meat and dairy processing plants, retail stores, food service outlets Municipal – inspection of retail stores and food service outlets -Public Health Inspectors Food grades of fruits & vegetables -Flavour & aroma, colour, tenderness & maturity, uniformity of size & shape, consistency of texture, appearance of the liquid medium (eg syrup), freedom of defects & foreign material Food grades of Beef -Canada Prime (highest): slightly abundant marbling -Canada AAA: small amount of marbling -Canada AA: slight amount marbling -Canada A: trace Food Grades of Eggs -Canada A (highest) -Canada B, C -Canada Nest Run (Lowest) oWeight, cleanliness, soundness & shape of shell, shape and position o yolk in egg during “candling”, size of air cell (small = fresh), abnormalities (eg blood spots) -Rejects, provincial cracks LESSON 5 Causes of Food Deterioration -Rxn w/ oxygen and/or light -Time -Physical stress or abuse -Inappropriate temperatures -Infestation by: insects, parasites and rodents -Food enzymes & other chemical rxns within the food itself -Microorganisms (bacteria, yeasts and moulds) -Gain or loss of moisture Classification of Food Deterioration -Perishable foods: Not processed or are only minimally processed and have a shelf life of less than 60 days -Semi-perishable: Last between 2 to 6 months as a result of some form of preservation method -Shelf stable: have a shelf life greater than 6 months Microorganism classification -Type: Bacteria (active or dormant), Yeast (slower but more tolerant to lower pH or water activity), Mold (even more tolerant to water activity and low pH), Viruses (pseudo-organisms; can be agents of food borne disease but do not cause food spoilage nor fermented foods -Function: Good, Bad, Ugly -Temperature Requirement: Psychrophiles, Psychrotrophs, Mesophiles, Thermophiles -Oxygen Requirement: aerobic, anaerobic, facultative anaerobe LESSON 6 Blanching: mild-intensity heat process; exposing fruit/veg to boiling water/steam for short time Preservation principle: inactivate endogenous enzymes, drive off O2 and other gases (min. pressure buildup – shelf-life extension) Pasteurization: moderate-intensity heat process; temp below B.P. of water 60-80C, 30-40 min@60C  low temp, long time (LTLT); 15 sec@72C  high temp, short time (HTST) Preservation principle: 1) low-acid foods (milk, eggs): to destroy pathogenic bacteria & viruses, to inactivate enzymes 2) acid foods (beer, wine, fruit juices): to extend product shelf-life; destroy spoilagecausing MOs & enzymes, acid foods not a source of th ( t E li0157 H7) t i d t i d

Commercial Sterilization (CS) high-intensity heat process; also known as “canning” (if it’s used in can product), requires a min. of 121C moist heat for 15 min. Preservation principle: destroys spoilage & disease-causing MOs, free from viable forms of MOs (including spores), ensures that spores of C. Botulinum are destroyed “botulinum cook” Why C.Botulinum important? Bacteria present in soil, water, air; strict anaerobe, grows well in low acid; produces a potent toxin (neurotoxin), small # of heat-resistant spores survive, but can’t multiply CS is conducted once food is packaged in suitable hermetically (impermeable to transmission of gas, liquid, MOs) containers (must withstand high temp & pressures), shelf-life of 2+ yrs UHT (Ultra High Temperature): injection of hot steam under pressure (140-150C) for a short time (4-6 sec), followed by immediate cooling. Aseptic Packaging: UHT food is aseptically placed into presterilized containers & sealed in aseptic environment; doing both shelflife > 6 months Thermal Death Curves (TDC): MOs not killed instantaneously, microbial death – logarithmic order of death, under constant thermal cond. Same % of microbial pop. destroyed in given time regardless of size of surviving pop; TDRC (rate curves) & TDTC (time curves) D-value (decimal reduction time): time (in mins) at a particular temp (C) required to kill 90% of MB pop z-value (slope): (temp) when D-value changes 1 log. F-value: time (min) required to kill MOs at 121C low acid foods use a 12D thermal process (MS) F = 12D; acid foods use 5D thermal process F = 5D Types of heat transfer: conduction (molecule to molecule in straight lines), convection (fluid motion, fluid heats along the hot wall of the container & rises) LESSON 7 Commercial freezing @-18C, home freezers @-12 to -14C, MOs cannot grow below -9.5C but some MOs can grow below 0C Lower temp + lower water activity = inhibit the growth of MOs Quality is max’d if able to form and maintain small ice crystals Cryogenic liquids = liquefied gases of extremely low boiling points LESSON 8 Dehydration – heat/energy transferred to the food (promoting water removal from food), water transferred from the food into the dehydrating environment Preservation principle microbial growth (need aw > 0.93), Staphylococcus aureus need 0.85, mold >0.6, Enzymatic reactions, chemical reactions (eg Maillard Browning @ aw >0.3) Water is physically removed to lower the water activity (aw), but MOs are not killed and resume growth after food is rehydrated Concentration: some of the water is removed from the food Changes during dehydration: shrinkage, case hardening, chemical changes Factors affecting dehydration: surface area, temperature, air velocity, humidity of drying air, atmospheric pressure & vacuum Methods for dehydration: -sun drying: dry, warm climates, slow drying method (days), fruits veg fish, inexpensive -spray drying: liquid foods & purees, tiny droplets sprayed into stream of heated air, rapid, instant coffee, tea, eggs, powder skim milk - tray & tunnel air drying: heated air at a set velocity with low %RH, poor rehydration properties, quick & inexpensive, pasta veg fruit spices -drum drying: food paste, purees, rotated heated drum, rapid drying (thin layer), dried food is scraped off (flakes), rehydration is fairly good, mashed potatoes, baby cereal -freeze drying: food must be in frozen state, water will sublime: water (solid)  water (vapour), no transition through liq. State, voids from ice crystals when water sublimes (act as channels), instant soups, highquality coffee, veg, military, rations, space food -vacuum microwave drying: (keep temp low = lower bp), microwave (rapid energy transfer), less nutrient loss, flavour retention, less colour change, complete rehydration, quick -deep fat frying: hot oil  evaporation of water, food will pick up oil, snack foods, bakery products -vacuum extrusion drying: slurry of food – steam heating, under pressure  release pressure  steam ↑ (puffing), moist heat causes starch gelatinization & cooking of the product LESSON 9 Biotechnology: application of science & engineering in direct or indirect use of living organisms or their parts in their natural or modified forms – refers to a broad range of techniques Preservation principle: microbial antagonism: suppress growth & metabolic activities of spoilage-causing microflora, metabolites: end products of fermentation, antimicrobial compounds (eg acids, alcohols), acids (formed in situ) can also lower pH of food; may need additional methods for preservation eg refrigeration, pasteurization or vacuum packaging Benefits of fermentation: Increased nutritional value & availability -More nutritious than the starting materials -Mold fermented foods (B-vitamins) -Microbial hydrolysis of cellulose materials that are indigestible by humans -Liberate nutrients from plants (otherwise indigestible in human GI tract) -Add variety to our food supply/diet Factors affecting fermentation: Starter culture -Specifically selected microbial cultures -Desirable traits for the particular fermentation -Metabolism leads to desired products -Eg acids, alcohol, flavour compounds -Dominant MO 1.As a “pure” culture (eg Yeast in bread) 2.From a previous batch of the fermented food containing that culture (eg sourdough or yogurt culture) 3.Part of the normal microflora (eg Sauerkraut, olives) Temperature -Starter cultures will only at their optimum temp. -Eg Sauerkraut flavour – proper succession of lactic acid bacteria

-However, the yeast ferments sugars more rapidly under anaerobic conds. Salt -Favours growth of Lactic acid-producing bacteria -Inhibits growth of spoilage/disease-cause MOs -Synergistic effect between acid & salt -More inhibitory to disease- and spoilage-causing MOs Cheese-making process -To start with the cheese-making, a starter culture is inoculated to milk. Rennet or microbial enzyme is added to set (coagulate) the milk. Curd is washed to remove excess whey. Salt is added to flavor the curd. Cheese then ages to produce characteristic changes & flavors What aspects of cheese (making) result in preservation? (longer shelf life compared to milk) -Moisture content & water activity, acidic conditions, lactic aci...