FOOD2000 END OF SEM Flashcards
1
Q
What is the general composition of meat?
A
- 70% water
- 21% protein
- 8% fat
- minerals (ash)
2
Q
What does the quality of meat depend on?
A
- breed
- heredity
- sex
- feeding
- pre-slaughter & slaughtering conditions
- dressing
- carcass cooling
- storage conditions
3
Q
What is the purpose of meat grading?
A
Establishes & maintains uniform trading standards & aids in determination of value of various meat cuts
4
Q
What is used to determine the class and grading of meat?
A
Dentition (number of teeth), weight & fat depth
5
Q
What are the steps in slaughtering?
A
- Stunning: renders animal unconscious, prevents pain/distress
- Sticking: severs major blood vessels in neck or thorax and animal bleeds to death (exsanguination)
- Skinning/Dehairing & Evisceration: minimises microbial contamination
- Inspection: done ASAP after slaughter to identify abnormalities or disease
- Washing & grading: fine spray of water to remove surface blood & bone dust, sometimes done using hot (water or by including low concentrations of organic acids)
- Refrigeration: done after being bled, skinned & eviscerated (removal of internal organs). Carcases are chilled for 24-48h before grading & processing
6
Q
What happens after slaughtering?
A
Chilling and aging
7
Q
What does chilling cause?
A
- Muscle contract & stiffen = rigor mortis
- as rigor mortis begins, meat becomes progressively less tender until rigor mortis completed
- Chilling done immediately after slaughter to prevent spoilage.
- Cold shortening = occurs when muscle chilled to <16°C before rigor mortis completion (meat becomes tough). Same result if carcase frozen before rigor mortis completion “thaw rigor”
8
Q
What does meat aging cause?
A
- Holding meat in refrigerator
- Increased tenderness due to natural enzymatic changes taking place in muscle.
- Beef held at higher temperatures tenderises faster BUT may also spoil
- Pork & lamb rarely aged = as already tender as relatively young
9
Q
What are Livestock marketing & prices affected by?
A
weather, feed prices, government import policies & consumer demands
10
Q
What is meat curing?
A
- preservative method
- flavour & colour enhancement
Some curing agents:
- Salt = preserve & add flavour.
- Sodium nitrate & sodium nitrite = fix red colour of meat, acts as a preservative & prevent microbial contamination
- Sugar = colour stability & flavour
- Spices = produce desired flavour
11
Q
What is meat smoking?
A
- Smoke protects fat from rancidity
- Contributes to colour characteristics
- Creates unique flavours in processed meats
- Smoke most effective microbial growth inhibitor when used with other preservation techniques
12
Q
What does meat colour indicate?
A
- Myoglobin = protein that is the primary colour pigment of meat (store oxygen in muscle tissue)
- Exposed to air/heat, goes from red to brown
- Oxygen present = meat is bright red colour
- Oxygen absent = meat is purplish in colour
13
Q
What are the Factors affecting milk composition?
A
- Nutritional factors: Type of feed and Quality of feed
- Non-nutritional factors:
- Breed
- Stage of lactation
- season & temperature
- Age & size
- Disease
- Milking frequency
14
Q
What are the by-products of milk?
A
- Concentrated & dried products
- Whey products
- Yoghurt
- Cheese
- Butter
- Ice cream
- Other fermented products
15
Q
What is yogurt?
A
- A semisolid fermented milk product
- Flavour varies but basic ingredients & manufacturing essentially consistent
- uses milk from cows
- Whole milk, partially skimmed milk or cream (GREEK) used
16
Q
What is the cooking function of eggs?
A
- Bind ingredients
- Leavening agent
- Thickening agent
- Emulsify mayonnaise, hollandaise sauce
- Glaze on breads & cookies
- Clarify soups & coffee
- In boiled candies & frostings = retard crystallisation
- Hard cooked & used as garnish
17
Q
What are the codes on eggs?
A
- After cleaned & checked for quality, every egg is stamped with unique code that identifies farm where it was laid = allows eggs to be traced back to farm of origin if necessary
18
Q
What is the composition of the egg yolk?
A
- Up to 35% liquid weight of egg
- Contains all the fat & just less than 1⁄2 the protein
- Contains higher proportion of egg’s vitamins and minerals
- Contains all the zinc
19
Q
What is the composition of the egg white?
A
- Contains more than half the egg’s total protein, niacin, riboflavin, and major inorganic compounds like chlorine, magnesium, potassium, sodium & sulphur
- protein containing all essential AA
- More opalescent than white
- More transparent in older eggs than fresher eggs
20
Q
What are the steps in egg quality control?
A
- Inspection: Eggs inspected by series of machines
- Dry Cleaning: using a soft bristled sanitised brush or by gentle rubbing with sanding sponge, cloth or paper towel (visibly dirty eggs segregated away from clean eggs)
- Washing: Some farms wash eggs in warm water & gentle sanitiser liquid as soon as collected = washing process is very fast & are dried immediately
- Light disinfectant: Many farms run eggs through UV light disinfectant system to kill any bacteria
- Internal quality: Bright lights to inspect egg’s internal quality = process called ‘candling’
- Candling: If any internal defects noticed, eggs removed & sent separate from first quality eggs
- Height and thickness: Tiny cracks not visible to human eye are checked & measuring height of egg white & shell thickness done
- Crack detector: Automatic acoustic crack detectors containing lots of small probes gently tap eggs at very fast speeds as they pass through machine = if cracks in eggshell, no matter how small, tapping energy will be absorbed, resulting in duller sound
21
Q
What does the egg structure contain?
A
- shell
- white
- yolk
- air cell
- chalaza
- germinal disc & membrane
22
Q
What are the three main egg farming systems?
A
free range, caged, barn-laid
23
Q
What are the Chicken meat processing steps?
A
- Inspection; classifying and grading
- Suspension and shackling of each bird by legs
- Stunned immediately with electric shock
- Bleeding
- Scalding to loosen feathers
- Feathers picked off by machine
- Removing of pinfeathers
- Evisceration
- Chilling in ice water
- Postmortem inspection
- Grading
- Packing
24
Q
What is the classification of butter?
A
Usually divided into two main categories:
- Sweet cream butter
- Cultured or sour cream butter made from bacteriologically soured cream (fermented product)
Butter can also be classified according to salt content:
- unsalted
- salted
- extra salted
25
How are meat carcases sold?
- Sides
- Quarters
- Wholesale cuts
26
In dried meats, what is the purpose of fermentation?
encouragement of lactic acid bacterial growth = useful as meat preservative & tangy flavour
27
What are textured protein products?
- at least 50% protein
- Contain eight essential AA & vitamins + minerals found in meats
- Soybean protein most commonly use
- Other proteins used = wheat gluten, yeast protein = used singly or in combination
28
What is the storage of eggs?
- Can be stored in shell at -1°C for up to 6 months
- Can be frozen out of shell for extended storage
- Eggs may be frozen as whole egg minus shell, separately as white & yolk
- For food manufacturing needs = eggs minus shell, can be dehydrated (dried) as whole eggs, whites, yolk using spray drying, tray drying , foam drying & freeze drying
29
What are blood spots on eggs?
- Occasionally found on egg yolk
- Don’t indicate a fertilized egg = caused by rupture of blood vessel on yolk surface during egg formation or by similar accident in oviduct wall
30
What is the composition of milk?
- primarily of water
- Carbohydrates
- Lactose
- Fat
- Protein
- calcium, phosphorus, magnesium, potassium, sodium, chloride & sulphur
- thiamine & riboflavin
- Solids-not-fat: lactose, caseins, whey, proteins & minerals
Fluid milk is; A colloidal dispersion of the protein casein & the whey proteins and An emulsion with fat globules suspended in the water phase of milk
31
What are meat substitutes?
Plant protein products
- Spinning vegetable proteins into fibres
- protein dissolved in alkaline solution then extruded & coagulated to form fibre bundles
- flavour & colour compounds and binders are added such as egg albumen or vegetable gum, emulsifiers
- Fibres then processed into shapes & textures
32
What are Physical properties of milk?
- Opacity = due to suspended particles of fat, proteins and certain minerals
- Colour = white to slight yellow (carotene content)
- isotonic
- pH and Acidity - important indicator of microbial quality of raw milk: pH of fresh milk = 6.6 to 6.8 (0.13% lactic acid)
33
What is the air cell in an egg?
- The empty space between the white & shell at large end of egg
- When egg first laid, its warm; contents contract as it cools = inner shell membrane separates from outer shell membrane = air cell formed
34
What is the chalaza in the egg?
- Ropey strands of egg white that anchor yolk in place in centre of thick white
- More prominent = fresher the egg
35
What does the colour of egg shell show?
Has nothing to do with egg quality, flavour, nutritive value, cooking characteristics or shell thickness
36
What is the effect of milk composition?
- Milk prices based on the milkfat and protein solids
37
What are the steps in cheese production?
- Treatment of milk
- Additives
- Inoculation & milk ripening
- Coagulation; Enzyme, Acid, Heat + acid
- Curd treatment (visco-elastic gel/coagulum)
- Cheese ripening
38
What is cheese?
- fresh or ripened product obtained after coagulation & whey separation of milk, cream or partly skimmed milk, buttermilk, or a mixture of these products
- Essentially the product of selective concentration of milk = casein, fat & water (10% cheese yield from milk)
39
What is butter?
- Represents about a 20-fold concentration of fat to milk
- Made by churning pasteurised cream at cool temperatures (< 10°C)
- Churning breaks fat globule membrane = emulsion breaks, fat coalesces & water (buttermilk) escapes
- Contains 80% milkfat
40
What are the membranes in the egg?
- Two shell membranes just inside shell; inner & outer; after egg laid = cools & air cell forms between two layers at large end of egg
- Vitelline membrane; covers yolk and protects from breaking = weakest at germinal disc & gets more fragile as egg ages
41
What is the germinal disc in the egg?
- The channel leading to yolk centre
- When egg is fertilised, sperm enter by way of germinal disc & travel to centre & embryo chick starts to form
42
What does the colour of the egg yolk depend on?
- diet of hen
- Pigments not changed during cooking
43
What are the types of emulsion?
- Oil in water emulsion (O/W): Oil droplets dispersed in
aqueous phase
- Water in oil emulsion (W/O): Water droplets dispersed in oil phase
44
What is emulsion?
- a dispersion of one fluid into another
- Fluids are normally immiscible (dont mix)
- Substance making up the droplets in emulsion is the discontinuous, dispersed or internal phase
- Substance making up the surrounding fluid is called the continuous or external phase
- Emulsifier coats emulsion droplets, preventing them from coalescing or recombining with each other
45
What are the basic steps of manufacturing ice cream?
- Blending of mix ingredients
- Pasteurisation
- Homogenisation
- Chilling & Aging the mix
- Freezing
- Packaging
- Hardening
46
What is ice cream made from?
basic white mix:
- milk
- cream
- skim- or whole milk powder
- buttermilk powder
- condensed milk
- whey powder
- anhydrous milk fat
- unsalted butter
47
In the ice cream process, what is pasteurisation?
Usually 80-85°C for ~15-30 sec
48
In the ice cream process, what is homogenisation?
- Essential for good smooth texture & even dispersion of ingredients
- Usually at ~75°C
- Reduces size of fat globules
- Increases surface area
- Forms membrane
- Makes possible the use of butter, frozen cream, etc.
- Controls “whippibility” and churning during freezing
49
In the ice cream process, what is chilling and aging the mix?
Mix is cooled to 2-5°C
- Then aged at this temperature
- Aging allows time for:
fat to cool down & crystallize,
for proteins & polysaccharides to fully hydrate & stabilise gel formation
- Aging carried out for 4-24 h depending on stabiliser used (gelatine takes 24 h)
50
In the ice cream process, what is freezing?
- Soft freezing (~50% water is frozen)
- Beating to incorporate clean air & freezing in scraped surface heat exchanger
- Fine even foam required = freezing rapid
- Temperature at outlet of freezer -1 to -9°C
51
In the ice cream process, what is packaging?
- when soft unless other steps required, e.g.: addition of fruits, nuts, candy, cookies
- At this stage, consistency same as soft serve ice cream
52
In the ice cream process, what is hardening?
~90% water frozen
- ice cream cooled to ~ -35°C in a blast freezer = should be as rapid as possible to ensure small ice crystals
- Must store ice cream at < -18°C after hardening
- Poor storage conditions are detrimental to ice cream quality
53
In the ice cream process, what is the blending of mix ingredients?
- Usually heated to 50-60°C to effect good mixing
54
What is the shelf life of ice cream?
- Only consideration is texture should be smooth
2 main problems:
- coarseness due to large ice crystals = slow cooling or melting/refreezing or fluctuating storage temperatures
- “sandiness” due to lactose crystals = can occur if lactose:water ratio is wrong
55
How do you maintain shelf life of ice cream?
- Formulate the ice cream properly
- sugar considerations
- stabilisers: bind free water
- Freeze the ice cream quickly
- Harden the ice cream rapidly
- Avoid temperature fluctuations during storage & distribution
56
What are the two main chicken hybrids?
- cobb and ross
- have been selectively bred for their growth, feed conversion (can feed them anything)
57
Do you want to cross breed chickens?
Yes as this creates stronger, more robust & health of cross is greater than the average of their parents (male parent = good muscling & body weight, while breeder hen = capacity to lay plenty of fertile eggs to be hatched into meat chickens)
- Don’t want inbreeding
58
What are the 2 main bacteria present that can cause illness in poultry?
salmonella and campylobacter
59
What are the Physio-chemical Characteristics of butter?
Main constituents (normal salted butter):
- Fat (80-82%; and maybe some milk solids-not-fat)
- Water (15.6-17.6%) = dispersed in fine droplets so butter
looks dry
- Salt
- Protein, calcium, phosphorous
- Fat soluble vitamins A, D & E :
Colour should be uniform
Should be dense and taste clean
Should be of smooth consistency so easy to spread & melt readily on tongue
60
What is the ice cream mix made up of?
- Fat
- Milk solids-non-fat (MSNF)
- Sweeteners
- Stabilisers
- Emulsifiers
- Flavours
61
What is the purpose of fat in the ice cream mix?
- Gives creaminess & improves melting resistance by stabilising air cell structure of ice cream.
- Whole milk, cream, butter or anhydrous milk fat (AMF)
- Milk fat can be replace by vegetable fat = refined or hydrogenated coconut oil & palm kernel oil most commonly used
62
What is the purpose of Milk solids-non-fat (MSNF) in the ice cream mix?
- nutritional value.
- water-binding & emulsifying effect.
- positive influence on air distribution = leading to improved body & creaminess
63
What is the purpose of sweeteners in the ice cream mix?
Increases solids content. Gives level of sweetness consumers prefer.
64
What is the purpose of stabilisers in the ice cream mix?
- Increase viscosity of mix & creates good texture.
- Control growth of ice crystals & improve melting resistance = producing firmer product (if not present = product becomes coarse & icy very quickly due to migration of free water & growth of existing crystals).
65
What is the purpose of emulsifier in the ice cream mix?
Include: egg yolk solids, glycerol monostearate (GMS).
- Develops fat structure & air distribution for smooth eating & good meltdown desired during freezing
- hydrophilic portion & a lipophilic portion reduces interfacial tension or force that exists between two phases of emulsion.
- Controls excess churning of fat during the freezing
66
What is the purpose of flavours in the ice cream mix?
Essences added before freezing. Solids (nuts, fruit, etc) added after freezing. Chocolate added to mix before pasteurisation as it often contains undesirable bacteria...
67
What are the processing steps of butter?
- aging
- churning
- working
- salting
- working post salting
- packaging and storage
68
In butter processing, what it the aging step?
Cream is subsequently cooled so a proportion of fat crystallises. If cooling rapid = crystals will be many and small. If cooling gradual = will have fewer but larger crystals & this gives butter a softer texture. Takes 12-15 hours
69
In butter processing, what it the churning step?
- Cream then pumped into churn, whipped with air. Breaks down fat globules = fat coagulates into butter “grains”. remaining (buttermilk) decreases.
- “Phase inversion” occurs, change from a fat-in-water emulsion (cream) to a water-in-fat emulsion (butter)
- Thus, cream split into two components = butter grains & buttermilk
- Traditionally, machine stops when grains have reached a certain size & buttermilk is drained off. In continuous butter maker: draining of buttermilk is continuous
70
In butter processing, what it the working step?
- Done after draining = butter is “worked” or “plasticised” (kneaded together) to continuous fat phase containing finely dispersed water phase.
- Breaks up embedded pockets of buttermilk or water into tiny droplets which are evenly dispersed in the fat.
- Small water droplets prevent bacterial growth = poorly “worked” butter = uneven distribution & sizes of water droplets = allow bacterial growth.
- Rarely now wash the butter to remove any residual butter milk & milk solids
71
In butter processing, what it the salting step?
Salt used to improve flavour & shelf-life, acts as a preservative. In batch production salt is spread over surface of worked butter. In continuous butter making, salt slurry is added to butter
72
In butter processing, what it the working post salting step?
Butter worked vigorously so salt is evenly distributed. Also influences product characteristics: aroma, taste, keeping quality, appearance & colour
73
In butter processing, what it the packaging and storage step?
Finished butter is discharged into packaging unit. Then put into cold storage
74
What are the types of yogurt?
- Set = incubated in container; additives such as fruit sink to bottom
- Stirred = incubated in tanks; gel disrupted by stirring, pumping, filling; additives well suspended
- Drinking type: similar to stirred type, but coagulum is broken down to a liquid
- Frozen type: incubated in tanks & frozen like ice cream
- Concentrated: incubated in tanks, concentrated & cooled before being packed, e.g.: Greek yogurt
- With Probiotics
- Some now also contain 'probiotics' or 'therapeutic' starters. These produce acid slowly compared with normal yoghurt starters. Common to add ingredients known as prebiotics, which will aid in growth of the probiotics in the colon
75
What is ripened butter?
Made from cream cultured with lactic acid bacteria which produce diacetyl & lactic acid. Has reduced pH due to lactic acid.
76
What is the process of butter?
Cream in storage tanks goes to pasteurisation
- Cream is stored cold for at least 4 h at ~5 °C before churning (to induce growth of some fat crystals)
Aging tank
- Here cream subjected to heat treatment program designed to give fat required crystalline structure that solidifies upon cooling
- Program chosen according to composition of butterfat
77
What are the nutritional properties of chicken?
- high quality protein
- low in fat
- Good source of phosphorus, iron, copper, zinc & vitamins B12 & B6
- Dark meat (leg, thigh) higher in fat than white meat (breast)
- Skin high in fat
78
What does Poultry products meeting consumer’s expectations depend upon?
- Conditions surround various stages in bird’s development from fertilized egg through production & processing to consumption
- appearance, texture & flavour are of primary concern to food industry & consumer
79
What are the characteristics of the egg shell?
- breed determines shell colour
- Accounts for 9-12% of total egg weight
- First line of defence against bacterial contamination
- Largely composed of calcium carbonate , plus small amounts of magnesium carbonate, calcium phosphate & other organic matter
80
What are the characteristics of the egg white?
- Egg albumin in raw eggs is opalescent & doesn’t appear white until beaten or cooked
- If yellow or greenish = riboflavin present
- Cloudiness = due to presence of CO2 that’s not had time to escape = indicates very fresh egg
81
How are eggs processed?
- Moment egg is laid = physical & chemical changes begin to reduce freshness
- Automated gathering belts gather & refrigerate eggs frequently
- Gathered eggs moved into refrigerated holding rooms = temperatures between 5- 7°C & humidity relatively high to minimise moisture loss
82
What is the major factor affecting taste of chicken?
bird age at slaughter
83
What is the minor factor affecting taste of chicken?
bird stain, diet, environmental conditions (litter, ventilation etc), scalding temperatures, chilling, product packaging, storage
84
What affects taste of chicken?
- When poultry cooked = flavour develops from sugar & amino acid interactions, lipid & thermal (heat oxidation) & thiamine degradation
- Poultry lipids & fats unique, & combine with odour to account for characteristic flavour
- Affected by few factors during production & processing
85
What are the three factors affecting meat quality?
Live production + animal state at production + poultry processing
86
What affects meat tenderness?
- feeding
- genetics
- species
- age
- muscle to muscle
- carcase suspension
- electrical stimulation
- mechanical tenderising
- chemical tenderising
- marinating
- freezing
- thawing
- cooking
- carving
87
How does feeding affect meat tenderness?
- What animal is fed doesn’t directly influence tenderness.
- Animals “finished” with grain reach slaughter weight sooner than animals “finished” to same slaughter weight (grass fed) = thus grain-fed animals usually sightly more tender as they are slaughtered at younger age.
88
How does genetics affect meat tenderness?
- ~45% of observed variation in tenderness.
- One of the main reasons for such wide tenderness differences existing among identical meat grades & cuts
89
How does species and age affect meat tenderness?
Tenderness variation = beef > lamb > pork > veal. Due primarily to chronological age of animal at time of slaughter.
Tenderness decreases as animal gets older = due to collagen. Pork & lamb from older animals = processed into sausage items, so toughness not a proble
90
How does muscle to muscle affect meat tenderness?
Considerable variation among muscles within any species = e.g. tenderloin much more tender than fore shank or heel
Connective tissue amount present
Carcase Suspension; Muscle stretching during carcase chilling affects tenderness.
91
How does electrical stimulation affect meat tenderness?
Done to “hot” carcases immediately after slaughter increases
tenderness. Beef carcases = 1 min of high-voltage electrical current = improves tenderness of many carcase cuts
92
How does mechanical tenderising affect meat tenderness?
Grinding is very popular means of increasing meat tenderness. Cubing another means of mechanically meat tenderising = small blades of cuber severs connective tissue, breaking it into smaller pieces
93
How does chemical tenderising affect meat tenderness?
Salt at certain concentrations increases meat tenderness. Salt tenderises by softening connective tissue protein (collagen) into more tender form. Hence cured meats (e.g. hams) more tender than uncured meats. Vegetable enzymes tenderise meat & used commercially & in homes. Work by degrading/dissolving connective tissues, collagen & elastin.
94
How does marinating affect meat tenderness?
Improves tenderness & adds taste variety. Basic ingredients include salt, acid (vinegar, lemon), & enzymes (papain, bromelin, ficin). Sometimes alcohol added for flavour. Addition of olive oil seal surfaces from air, result in meat fresher & brighter for longer
95
What is Tenderness, juiciness & flavour?
components of meat palatability; tenderness can considerably vary from one cut to next
96
How does freezing affect meat tenderness?
When meat frozen very quickly = small ice crystals form. When meat frozen very slowly = large ice crystals form = disrupt components of meat muscle fibres & slightly increase tenderness BUT also increase juice loss upon thawing (less juicy and tender)
97
How does thawing affect meat tenderness?
Done slowly in refrigerator results in greater tenderness compared with cooking from frozen. Slow thawing minimises effect from cold shortening & reduces moisture loss. Microwave thawing should be done on low power
98
How does cooking affect meat tenderness?
As progresses, contractile meat proteins become less tender & major connective tissue protein (collagen) become more tender
99
How does carving affect meat tenderness?
- cut at right angles or 'against the grain' to length of muscle = severs maximum amount of connective tissue & bone more evenly distributed in that areq; achieves maximum tenderness
- Cutting “with the grain” = “stringiness” & thus less tenderness
100
What does chicken texture depend on?
- chemical & physical changes in chicken muscle as it becomes meat
- rigor mortis e.g struggling before or during slaughter = rigor mortis forms faster = toughness of muscle due to reduced energy in live bird...
- Environmental stress (hot/cold temps.) before slaughter create similar outcome
- High stunning or scalding temperatures = cause toughness of poultry meat
- For boneless = influenced by amount of time between death & deboning
- Muscles deboned during early post-mortem become tough as they still have energy to contract. Avoided by aging meat 6-24 hours before.
- post-slaughter electrical stimulation used immediately after death to hasten rigor development & reduce aging time before deboning = electricity applied to dead bird, energy used up & rigor mortis entered at faster rate, meat deboned within 2 hours post-mortem instead
101
Why does rigor mortis occur?
Animal dies, blood stops circulating, muscles receives no new oxygen or nutrient supplies, no oxygen or nutrients cause muscles to run out of energy, they contract & become stiff
102
What is the appearance of chicken meat?
- affected by bird age, sex, strain, diet, intramuscular fat, meat moisture content, pre-slaughter conditions
- meat colour depends on presence of myoglobin & haemoglobin
- Breast muscle most susceptible to discolouration
- Discolouring also caused due to environmental temperatures or stress in live handling or bruising
103
What is ice cream?
- Unfermented
- Is greater than 10% milkfat & as high as 16% fat in premium products
- 9-12% milk solids-not-fat: caseins & whey proteins, lactose
- 12-16% sweeteners = sucrose & glucose-based corn syrup
- 0.2-0.5% stabilisers and emulsifiers
- The above values are percentage by weight in mix, but when frozen, half of the tub is air
104
How is chicken meat processed?
- Processing companies generally contract out growing of chickens to contracted chicken growers, which own the farm, shedding, equipment, labour, bedding but does not own the chickens, or provide feed, medication & technical advice
- culling chickens ‘thinning out’ or ‘partial depopulation' = may be done up to five times, allows more space & helps with optimal barn temperature, plus air & litter quality
- First harvest might occur as early as 30-35 days, & last harvest at 55-65 days
- Chickens often harvested at night under low light = its cooler & birds more settled
- Birds usually caught by hand, placed into plastic crates for good ventilation & protection from bruising
- Sometimes chickens collected by machines using conveyor belts to move birds from barn floor & deposits them into crates
- Crates/modules then handled by forklift equipment & onto trucks for transport to the processing plant
105
What are the types of dairy milk as a beverage?
- Regular or full-fat: 3.2% to 3.8% milk fat
- Reduced-fat: ~2% milk fat
- Low-fat: <1.5% milk fat
- Skim/no-fat: 0.15% milk fat. Milk solids (water removed from liquid milk) added to optimise the taste
106
What are the issues with precooked meat products?
- recontamination & incubation of spoilage microbes
- most serious with repeated warming & chilling
- Canning = sufficient heating to control spoilage microbes, sealing prevents recontamination and microbial growth
107
How to best cook meat?
- Cuts low in connective tissue = steaks = dry heat cooking including pan frying, grilling or BBQ, meat flavour develops before contractile proteins have opportunity to become significantly less tender
- Cuts high in connective tissue = those from fore shank, heel & chuck = long & slow cooking at low temp using moist heat such as braising, results in tough collagen converted into tender gelatine = more tender than with dry heat
108
What are the processing steps of cheese?
1. Cheese milk clarified, separated & standardised and Pasteurised; HTST. Results in a soft, weak curd at renneting.
2. Additives
- Calcium chloride; reduces amount of rennet required. Colour, Lipases , starter cultures; Lactic acid
3. inoculation, milk held for 45-60 min at 25- 30°C = ensures bacteria are active
4. Coagulation; Gel formed by destabilising casein micelles. Rennet most often used for enzyme coagulation
In acid treatment: more fragile due to loss of Ca. Eg cottage and cream cheese
In heat + acid treatment: Heat causes denaturation of whey proteins which interact with caseins
5. Curd treatment; After milk gel reach desired firmness, its cut into small pieces and immediately begin to shrink & expel whey (syneresis). Increase in temperature causes protein matrix to shrink, lactose increases. When curd reached desired moisture its separated from whey. Some cheese varieties include curd washing
6. Ripening; Varies from weeks to years; Temperature, humidity & time controlled
- Cheeses covered to protect against moisture loss & mould growth – dipped in wax, vacuum packed
- Degradation of lactose, proteins & fat carried out by ripening agents
109
How is yogurt produced?
- Milk is clarified, separated into cream & skim milk, then standardised to achieve desired fat content
- Mixed: ingredients blended in mix tank equipped with powder funnel & agitation system -> fortification of milk to increase milk solids-not-fat: improves consistency & flavour. Pectin or starch or gelatine added sometimes to increase viscosity.
- Mixture then pasteurised
Varies = 85°C/30 min to 90-95°C/10-20 min
Helps formation of casein network
Increases gel firmness and decreases syneresis (release of whey from gel)
Shortens coagulation time, increases pH at which coagulation occurs
- Then homogenised (at 50-60°C) = to improve viscosity & firmness of coagulum; Even dispersion of constituents, solids-non-fat & fat
- Mix cooled to temperature optimum for starter culture growth (40-45°C)
- Starter cultures: (ST) & (LB)
ST grows faster & produces both acid & CO2 which stimulates LB growth.
Proteolytic activity of LB produces stimulatory peptides & amino acids used by ST.
Microbes ultimately responsible for typical yoghurt flavour & texture. Incubated till firm gel forms (5-7 h)
- Stir (for stirred yoghurt) & cool
- Add fruit if required
- Pack, store, dispatch
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How are plant based meat products made?
- Extrusion method
- Vegetable protein combined with flavour, colour & other ingredients
- Formed into a plastic mass in a cooker-extruder
- Mass forced through a die under pressure to form beef-like strips or other characteristic meat shapes
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What are the practices of milk production?
- Raw milk fresh is almost sterile
- Post-milking handling MUST maintain milk’s nutritional value & prevent deterioration
- Most cows milked twice a day (some farms milk 3 or 4 times/day)
- Raw milk immediately cooled from the cow’s body temperature to below 5°C
- Then stored at farm under refrigeration until pick up by insulated tanker trucks
- When raw milk pumped into tanker, a sample is collected for later lab analysis
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How is milk processed?
- Raw milk arriving at milk processing plant is tested for quality
Quality assurance of raw milk:
- temperature
- flavour & odour
- Composition
- Antibiotics
- Freezing point depression
- pH/Acidity
- Butterfat (BF) and solids-non-fat (SNF) of raw milk also analysed (vary according to time of year, breed of cow & feed supply)
- Price is determined on BF & SNF content, and volume
- Once passes receiving tests, milk pumped into large refrigerated silos of processing plant
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How is milk seperated?
- centrifugal separation
- Separates cream & skim portions of milk
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What is butter fat?
- Accounts for different types of products; whole milk, non-fat
- Two streams produced during separation of whole milk: fat-depleted stream (produces the beverage milks) and fat-rich stream (cream)
- further processing; butter, ice cream
- Sold to processing industries = higher fat content than retail sold creams
- “Plastic” cream produced from certain types of separators. Remains an oil-in-water emulsion
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What is milk pasteurisation?
- heating raw milk to kill all pathogens
- Some harmless bacteria may survive heating process; Cause milk to “go sour” (refrigeration slows growth bacteria)
- not sterilisation as doesn't remove all bacteria
1. Low-temperature longer time (LTLT) pasteurisation: A batch method; Heats milk to at least 63°C for at least 30 min OR 65°C for 15 min. Can cause a “cooked” flavour, so not always used for fluid milk products
2. High-temperature/short time (HTST) pasteurisation: A continuous method heating milk to 72°C for at least 15 sec. Milk immediately cooled to below 4°C & packed into plastic bottles or plastic-coated cartons
3. Ultrapasteurisation: 135°C for 2 to 5 sec, followed by rapid cooling to 7°C or lower. Sterilisation of milk occurs when heated to 137°C - 150°C for 2 to 6 sec = called ultrahigh temperature (UHT) processing
-UHT milk in cartons, doesnt require refrigeration until its opened
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How long does raw milk have to be processed after its receipt?
72 h
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How is processed milk packaged?
- various size containers, under strict sanitation
- Daily washing and automatic “Clean-in-Place” (CIP) systems used; minimises manual handling, reduces contamination
- Packaged products to cold storage warehouse (stored for short time)
- Transported to supermarkets on refrigerated trailers
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What is the nutrition of processed milk?
- Vit A & D often added
- in form of a water-soluble emulsion
- Vit A lost during fat separation/heating, while Vit D not present
- addition of milk solids to meet standards
- Solids represent the natural mineral (Ca, Fe), protein (casein) & sugar (lactose) portion of nonfat dry milk
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What is milk homogenisation?
- Cream portion prevented from rising to top of package
- Milk forced under high pressure through narrow gap
- Breaks up the butterfat globules to small sizes
- Such small globules will not coalesce (stick together)
- Nutrition or quality not affected
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How is quality control done for processed milk?
- microbial presence; standard plate count (SPC) and “Ropey” milk test
- calibration equipment; analyse butterfat & solids-not-fat
- use-by date on package
- Samples of each product packaged each day are saved to confirm freshness 7 days after use-by date
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What are Concentrated and dried dairy products?
- Concentrated milk products obtained through partial water removal
- Dried dairy products have less than 4% water usually
- Benefits: increased shelf life, convenience, product flexibility, decreased transportation costs & storage
Products include:
Evaporated Skim or Whole Milk
Sweetened Condensed Milk
Condensed Whey
Milk Powder
Whey Powder
Whey Protein Concentrates (WPC)
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What is whey protein concentrate/whey powder?
- ultrafiltration
- Reverse osmosis to concentrate whey
- Lactose crystallisation; decrease hygroscopicity
- evaporated, then dried
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What is milk powder?
- more severe heat treatment
- Milk evaporated prior to drying
- Homogenisation to decrease free fat content
- Spray drying
- Post-spray drying, powder packed to protect from moisture
- Skim milk powder; rehydrating dried milk powder = then dried = increased amount of air between particles
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What is sweetened condensed milk?
- longer shelf life due to sugar; increases osmotic pressure
- heat treatment after raw milk standardised; destroys microbes
- Sugar is added before & after evaporation, to avoid viscosity changes then cooled & lactose crystallisation is induced
- Milk is inoculated, then rapidly cooled
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What is evaporated milk?
- Concentrated at low temperatures by vacuum evaporation
- second standardisation done to balance salts (protects milk from extensive heat treatment)
- After salt balanced, product is quite perishable = fat easily oxidised
- sterilised in an autoclave
- Continuous flow sterilisation is followed by packaging under aseptic conditions
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What is condensed whey?
Whey from cheese making is condensed by evaporation
Contains lactose, lactoglobulin, lactalbumin & water
Fat generally removed by centrifugation & churned
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How can fish be classified?
1. saltwater and fresh water varieties
2. basis of fat content:
- Lean = <2% fat
- Fat = >5% fat
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What is another word for fish?
finfish
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What are shellfish?
1. Include molluscs
- are soft-bodied & partially or wholly enclosed in hard shell composed of minerals, E.g. = oysters, clams, abalone, scallops & mussels
2. Include crustaceans
- are covered in crust-like shell & have segmented bodies E.g = prawns, lobsters, crabs, Morten Bay bugs
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What is the correct storage for seafoods?
- Fish with bruises, punctures or sitting in its juices = spoil more rapidly
- Fish & shellfish should be cooked within 2 days
- When thawing; do in fridge to avoid drip loss & taste, texture adversely affected
- for crustaceans, keep damp but not placed on ice or airtight container will kill them
- lobsters remain alive for ~24h
- Should scrub mollusc under cold water, just before opening or cooking
- soaking them in water with flour or cornmeal to encourage them to eat to clean out the grit only shortens their life
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What are fish by-products?
* Fish protein concentrate (FPC) or fish flour
- produced from dehydrated & defatted fish
* Roe = mass of eggs & sacs of connective tissue
- cooked by parboiling, or eaten salted & dried, smoked, or preserved in brine (caviar = sturgeon roe)
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What contributes to fish spoilage?
- Fresh fish held at 16°C only good for 1 day or less, whereas At 0°C = fish may remain good for 14 to 28 days
- Happens quicker than meat = bacteria on skin & in digestive tract attack all tissues
- Fish struggle when caught = convert glycogen to lactic acid before death
- Fish fat has phospholipids containing trimethylamine oxide (TMAO) which regulates osmotic pressure. Fish die = TMAO converted by bacterial enzymes to “fishy” smelling liquid substance trimethylamine
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What are the properties of fresh fish?
- eyes should be bright, clear, protruding
- Skin should be shiny
- Scales should be brightly coloured & tightly attached to skin
- Gills should be red & free of slime
- Flesh should be firm, elastic & not
separated from the bones
- Fillets should have fresh cut appearance & colour resembling freshly dressed fish
- fresh odour
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How is seafood regulated?
* standards by the Federal and State government
* Hazard Analysis and Critical Control Point (HACCP) principles in place
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Examples of seafood products
- Drawn fish = only entrails removed
- Dressed fish = scaled & eviscerated, & usually head, tail & fins removed
- Steaks = sections dressed fish
- Fillets = fish sides cut lengthwise away from backbone
- Sticks = uniform fish pieces cut lengthwise or crosswise from fillets or steaks
- Nuggets = like fillets but only smaller
Some fish manufactured into:
- breaded, formed & imitation products
- cured or canned products
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How can shellfish be marketed?
- in the shell
- shucked (removed from shell)
- headless (prawns)
- as cooked meat
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What is surimi?
- paste made from fish
- Machines used to obtain minced fish flesh from filleting wastes & underutilised fish species
- Minced fish flesh is washed to remove solubles
- Left over odourless, flavourless, high- protein product called surimi
- Can be combined with other flavours, colours & anti-denaturants before freezing
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How is seafood preserved?
- drying, curing or smoking
- Refrigeration, freezing & canning
- fish individually frozen = glazed with layers of ice to protect fish surface from oxidation & freezer burn
- glazing done by dipping fish/prawns in cold water & then freezing a layer before dipping fish again
- low-fat fish frozen, higher fat canned
Typical canning operation:
- thaw frozen fish received
- eviscerate
- clean and sort
- precook and cool
- seperate and compact meat
- seal cans & sterilise
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When is seafood grading done?
- Done after inspection & determines quality level
- Only products that have an established grade standard can be graded
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What is fish grading based on?
- Appearance = flesh consistency, odour, eyes, gills & skin
- Discolouration
- Cutting & trimming defects = body cavity cuts, improper washing, improper deheading & evisceration defects
- Improper boning (for boned styles = fillet only) = refers to presence of unspecified bone or bone piece
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What are the vitamins and minerals in fish?
- biotin & niacin
- vitamins D & A found mainly in fish liver oils, but some high-fat fish good source of vit A
- iodine, phosphorus, potassium & zinc
- canned with edible bones; calcium
* Oysters; iron & copper
* Saltwater fish; excellent iodine source
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What is the composition of fish and shellfish?
- low in fat
- high in minerals & vitamins
- complete protein source
- fat is unsaturated
- polyunsaturated cholesterol
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What are the steps in fish processing?
1. receiving and weighing fish at live processing plant
2. holding fish alive until needed
3. stunning
4. deheading
5. eviscerating
6. skinning
7. chilling
8. size grading
9. packaging
10. transportation of finished product
Some fish will also include freezing
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What is ultra-processed food?
- food products that are convenient , durable, highly profitable, highly attractive, hyper palatable
- derived from foods with little or no whole food
- low nutritional quality
- high glycemic index, low satiety potential
- cheap
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What are methodologies for ultra-processed food?
- Hydrogenation & hydrolyzation
- Extrusion
- Moulding
- Pre-processing for frying
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How are ultra processed foods made palatable?
- colourings
- flavourings
- emulsifiers
- thickeners
- other cosmetic additives (e.g. sorbic acid, benzoic acid and their salts - sodium benzoate)
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Unprocessed/minimally process food
foods which did not undergo processing techniques such as pasteurising, fractioning, grinding
e.g legumes, fruit, veg, eggs, chicken
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Processed culinary ingredients
Obtained from minimally processed foods and used to season, cook and create culinary ingredients, edible wax
Home cooking that you know all the ingredients going in
E.g salt, sugar, vegetable oils, butter
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Processed Foods
Unprocessed or minimally processed foods or culinary dishes which have added culinary processed ingredients. Necessarily industrialised. Long shelf life.
E.g bread, cheeses, pastes, meal/fruit/veg bottled in salt or sugar solution
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Ultra processed foods
Food products derived from foods or parts of foods added with cosmetic additives, not used in culinary. Longest shelf life.
E.g breast milk substitutes, cookies, ice cream, nuggets, soft drink
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UPF consumption and health
- the more UPF, the higher amount of sugars, fats, sodium & calories
- associated with increase in risk of overweight/obesity. high waist circumference, low HDL-cholesterol levels & metabolic syndrome
- less common but still associated with cardiometabolic risk, higher risk of CVD, cerebrovascular disease, depression & all-cause mortality
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UPF in pregnancy
- high impact even on unborn child
- maternal nutrition important
- increases childs risk of allergies, asthma, etc
- linked to post natal depression, gestational diabetes
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UPF on the gut brain axis
Relationship with dysregulation of gut microbiota & its influence on the development of cognitive decline
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Foods you may not realise are UPF
Breakfast cereals: contain maltodextrins, processed proteins & fibres, and colours
Protein & Muesli Bars and Balls: contain processed fibres & proteins, non-caloric sweeteners
& invert sugars glucose & fructose
Plant-based “milks”: contain emulsifiers, vegetable gums & flavours
Packaged Breads: some contain emulsifiers, modified starches
Yoghurts: contain additives like thickeners, non-caloric sweeteners
or flavours (so choose plain yoghurts)
Meal bases & sauces: typically contain thickeners, flavour enhancers & colours
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Are all UPF bad?
- displace nutritious meals
- sometimes choices are limited
- minimally processed foods need to be more available and affordable
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Boxed beef
- vacuum sealed meat: prevent spoilage and shrinkage
- extended shelf life
- bones and fat removed
- smaller portions
- reduces shipping and labour costs
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Meat freezing
- meat fat eventually oxidises
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What are the three most common meat pigments?
myoglobin; not holding oxygen
oxymyoglobin; holding oxygen
metmyoglobin; holding water
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antemortem inspection
inspection done for lot of birds before slaughter
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plant based milk processing;
1. raw material
2. extraction
3. seperation
4. formulation
5. homogenisation
6. pasteurisation (UHT)
7. packaging
