Poultry and Eggs Flashcards
Worldwide poultry consumption is (increasing/decreasing). Why?
increasing
lower in fat (less saturated, skin is easily removed)
cheap to produce
How does Canadian poultry consumption compare with other proteins?
Most protein consumed is chicken
Eggs are also significant source
Why has the increase in poultry production and consumption worldwide decreased slightly in recent years?
Bird flu in China
restrictions on import, consumption
Most of Canada’s poultry is produced in:
Ontario (followed by Quebec)
Define poultry; what are the most commonly consumed types?
meat from domesticated fowl (birds)
chicken > turkey > duck > goose/guinea fowl
What determines the “yield” of poultry?
relative % of meat (with skin and bone removed)
What are the classifications for turkey meat? (2)
Roasters (16-24wks)
Hen/tom turkey (old breeders) - >52wks
What affects the composition of poultry meat? (5)
breed age sex growth environment diet
Name 2 canadian breeds of chicken, and what they are known for.
Red shaver, Chantecler
more meat, able to withstand cold
Compare the compositions of chicken, duck, and quail/pheasant
chicken: 50% meat, 35% bone, 15% skin
duck: less bone and meat, but more skin (fatty)
quail/pheasant: much higher meat yield (>75%), with less bone and skin
What are the poultry classifications for chicken (6)? What is it based on?
weight and age
broilers: 6-8wks - 1kg Fryers: 6-8wks - 1-1.4kg roasters:>8months - 1.4-2.2kg stewing hen: >10months - 2.2-3.2kg capon (neutered male): 3.2-3.6kg rooster: >10months - 3.2-3.6kg
Poultry meat may be described as ____ or ____. What are the differences?
white; dark
white is lighter, higher protein, lower fat
dark is redder, higher fat
The fat content of poultry can be decreased substantially by;
removing skin
What are the 3 classes of processed meats?
minimally processed - salted/cured
moderately altered - sectioned and restructured
extensively altered - highly processed, reduce to tiny particles and reformed
Compare the lipid profiles of duck and goose, vs chicken and turkey.
What implications does this have?
duck/goose have more lipids, high in MUFAs (mostly oleic)
chicken/turkey less lipids, higher in PUFAs (linoleic, linolenic, arachidonic)
omega 3 and 6 especially beneficial, but more prone to rancidity/spoilage
What is MDPM or MSPM, and how is it obtained? What is it used for?
mech. separated/deboned poultry meat
remaining meat taken from carcass after meat cuts are removed
use high pressure on carcass inside a sieve chamber -> meat scraps sieved through, while bones remain in chamber
use for formed processed meats (hot dogs, lunch meat)
Meat processing can involve ___, ___, or ___ processes, and serves to: (3)
thermal, mechanical, chemical
increase shelf life
alter texture/taste (variety)
convenience
Duck and goose meat have higher amounts of ___ and ___.
dark meat
lipids
what additive for processed meat will increase water holding capacity by affecting muscle proteins? Describe the mechanism
polyphosphates
polar, so binds water
also will promote dissociation of ACTOMYOSIN -> actin and myosin (separated, will have better WHC)
______ phosphates increase WHC, reduce ____, and help preserve ____, while _____ phosphates ___________.
alkaline; reduce oxidation; preserve color
acidic; reduce bacterial growth
The role of most additives for processed meat aim to: (2)
increase water holding capacity
increasing binding ability
What are the effects of salt on meat? (4)
reduces WHC, extracts salt-soluble proteins, reduce Aw, reduce microbe activity
True/False: salt is essential for the curing of meat.
True; however it is not the actual curing agent.
What is “curing?”
treatment of meat with nitrates/nitrite and salt to preserve and obtain certain taste/color/texture
Why would soy be added to meat products? (3)
increase WHC
binding
reduce cost
The actual curing agent in meat is:
NO
precursors are NO3 or NO2
What is the role of nitrites in processed meats? (4)
- stop bacteria growth (especially C. botulinum)
- develop flavor
- develop and stabilize color
- reduce oxidation
Can nitrosylmyoglobin be returned to normal Mb?
Yes, if not heated then binding is reversible
Describe the mechanism for color development in cured meat, and the necessary reagents.
- Nitrite and reducing agent (Na erythryorbate) is added
- Nitrite will dissolve in water, release nitrous acid
- Will be reduced to NO
- NO bind to heme in Mb -> nitrosylmyoglobin (MbNO) - pinkish (not yet stable)
- heat -> globin is denatured -> nitrosylhemochromogen (stable pink)
The egg yolk contains the ______, which the site of potential fertilization.
germinal disc
Why are reducing agents needed in cured meat (4), and what is commonly used?
- antioxidant - stabilize color/flavor
- produce NO from nitrites
- reduce metMb back to Mb
- reduce NITROSAMINE formation (carcinogen)
Na erythryorbate (isomer of ascorbate) Can also use nitrate reductase (enzyme from animal tissue), but require H donor (NADH)
The top producers of eggs in Canada are:
Ontario, followed by Quebec
The egg shell is mostly composed of: ____ with small amounts of: ______
Calcium carbonate
small amounts of Mg carbonate, Ca phosphate, organic matter
How are live chickens converted to poultry? (6)
Slaughter:
- stunned (electric or with CO2/argon)
- neck slit -> bleed out (blood has enzymes/staining/coagulate)
- scalded in hot water
- plucked (feather removal)
- evisceration/giblet removal (remove heat/feet/organs)
- chill whole carcass, or portion further into cuts
MSPM is especially high in _____.
minerals
What are some antimicrobial agents that can be used to rinse meat? (4)
acidified NaCl
Cl dioxide
peroxyacetic acid
peroxyoctanoic acid
What are 3 texturizer types used for processed meat?
- gelatin
- TGA (tranglutaminase; meat glue)
- protease inhibitors: prevent post-mortem degradation
(CYSTATIN from potato powder, or ALPHA-MACROGLOBULIN from blood plasma)
why would starch be added to processed meat?
increase WHC
How does gelation of meat occur? (3)
- denaturation
- aggregation of proteins due to hydrophobic interaction
- cross links form between AAs -> creates VISCOELASTIC GEL
Describe emulsions prepared from meat:
emulsion of fat and protein: fat globules distributed uniformly through myofibrillar and connective proteins
Does the egg shell form a solid barrier? Explain.
NO; porous surface that allows for gas exchange.
But has a keratin/collagen cuticle layer that prevents microbe contamination
around ___% of the world’s eggs are produced in developing countries.
75%
A prominent ____ in the egg white indicates freshness.
chalazae (anchor for yolk, white strand)
What causes the air cell in the egg, and what does it indicate?
contents of egg will contract after being laid as it cools
larger air cell means older egg
The inner egg is surrounded by 2 ____, which protect from _____, and have the ____ in between.
membranes
bacteria
air cell
What are the 2 main edible parts of eggs?
Albumen (egg white) - thin and thick (63%)
Yolk - major source of nutrients (27.5%)
What are some uses for eggshells? (5)
Ca supplement Gardening cosmetics Fining/clarifying agent compost
egg white solids are high in _____, which depends on the ______. It is low in ___, and very low in ____.
protein; age of the hen (around 10%)
carbohydrates (1%); fats (0.03%)
pigments known as ____ will determine the color of the eggshell.
ooporphins
egg whites are known for their ____ ability, while the yolk has excellent ____ ability.
foaming
emulsifying
What form are egg white carbohydrates in? How are they removed, and why would this be necessary?
liquid form, as free monosaccharides or glycoproteins
remove by GLUCOSE OXIDASE -> gluconic acid + peroxide
use CATALASE to break down peroxide -> water
needed when processing egg whites further, in order to prevent maillard rxn (discoloration and flavor)
ovalbumin has what properties?
fat carrier, foaming abilities
Which EW protein is resistant to heat coagulation?
ovomucoid; due to carbohydrates attached
What compound is of concern when eating raw egg whites?
Avidin - will bind to biotin and decrease bioavailability
List the major proteins in egg white: (6)
OVALBUMIN (54%) OVOTRANSFERRIN (12%) OVOMUCOID (11%) LYSOZYME (3.5%) OVOMUCIN (1.5%) Other globular proteins, mostly enzymes
____ protein is found in the egg white, and is good as a thickener because it: ______
ovomucin
coagulates easily with heat
____ is a ____ protease inhibitor found in egg white
ovoinhibitor; serine
____ is an enzyme in egg white that is anti_____. It is (highly stable/not stable) under thermal processing
lysozyme
anti-bacterial
highly stable
What determines the egg yolk color, and what indicates a high quality egg?
feed of hen (hen does not synthesize any pigments)
round yolk
Since the egg yolk is higher than the white in ____, it would be (less dense/more dense). What structure prevents it from floating to the top?
lipids; less dense
chalazae (protein strand anchor)
What is the composition of egg yolk?
water (48%)
protein (16%)
fat (33%)
What is the density, composition of HDLP? What form is it in egg white?
density > 1.0
higher in protein (vitellin), lower in fat (only 20%, mostly PL)
rich in P
contain PHOSVITIN - lipid free, P rich protein
form insoluble granules
What is the density, composition of LDLP? What form is it usually in egg white?
density < 1.0
high lipids (mostly TG, PL, some cholesterol)
tiny micelles suspended in plasma
What are the main egg phosphoproteins, and how can they be solubilized?
phosvitin (most P!) - weak salt solution
vitellin and vitellenin - in alkaline solution (not acid or neutral)
What is the function of protein in egg yolk (2), and what are the types? (5)
Serve as transporters and help maintain osmotic balance Lipovitellin (HDLP) Lipovitellinin (LDLP) Livetins (lipid free globular proteins) Phosphoproteins other small globular proteins (enzymes)
Most of the yolk lipids are present in the ___ and ___ fractions.
HDLP; LDLP
What is the lipid composition of egg yolk?
mostly TG: 66%
PL: 28%
cholesterol: 5%
also some FFA and carotenoids
What is the fatty acid composition of yolks, and does it vary?
MUFAs (45%) - mostly oleic
SFAs (35%) - mostly palmitic and stearic
PUFAs (25%) - omega 3 and 6
SFA stays constant, but can change level of PUFAs with feed, while decreasing MUFA
Why are eggs important in the diet? (5)
high in protein
excellent protein profile (all essential AA in good proportion)
PUFAs: has EFAs and ALA content
all vitamins except C - especially high in vitamin D
Good source of Fe, P
Are eggs a good source of Ca?
Not the edible portion (only a little in yolk)
The major sterol in egg yolk is _____. What forms is it found in?
cholesterol
Free (84%)
CE (16%)
Lecithin is also known as: ____. Why is it an excellent emulsifier?
phosphatidylcholine
forms amphiphilic zwitterion over wide pH range, so widely applicable in products
What are “designer eggs”?
enhanced content of PUFAs (omega 3, EPA, DHA) by altering bird feed
also can enhance vitamin A or E
What is the main safety concern with eggs?
Salmonella enteritidis, from oviduct, feces, or possibly before laying
(should refrigerate eggs)
For the food industry, eggs have importance both as _____ and ______.
food; functional processing aids
What are some functional properties of eggs and their derivatives?
- emulsifying
- foaming
- gelation/coagulation with heat
