what is the cost of poultry compared to other meats?
relatively inexpensive source of protein compared to other muscle foods
why is poultry less of a dietary problem?
religious reasons, space requirements for cultivation, rapid growth, amount and nature of fat (relative to beef and pork)
what are chicken broilers/fryers?
first group of chickens at ~6-8 weeks
meat is tender with softer bones and cartilage
what are turkey broilers/fryers?
first group of turkeys at ~10-12 weeks
meat is tender with softer bones and cartilage
what is the second group of chickens and turkeys?
roasters
chicken=8-12 weeks old
turkey=16-24 weeks old
what is a spent chicken or turkey?
≥52 weeks
considered not productive because they no longer produce eggs
meat tends to be tough and dry
why is the meat of spent chickens/turkeys tough and dry?
extent of collagen cross-linkage formation increases as the animal ages
is the per capita consumption of poultry in North America increasing or decreasing?
it is growing steadily
what is the percentage of meat, bone, and skin on a chicken?
52% meat
34% bone
14% skin
what is the percentage of meat, bone, and skin on a turkey?
67% meat
21% bone
12% skin
which species has the highest %meat for its size?
pheasant and quail both have 76%
which species has the lowest %meat for its size?
duck, at only 34%
what is different about poultry meat when it is produced with skin on?
tends to have a higher fat content and lower moisture/protein content
what can be inferred about the skin of poultry based on what happens to the meat if cooked skin on?
it is much higher in fat than the rest of the animal
why is some meat dark and some meat light?
meat that is dark has a higher relative amount of myoglobin present
where are the white muscles found on a bird?
those parts used for intense and rapid activity, such as the wings and the chest muscles that control wing movements
where are the dark muscles found on a bird?
used for less vigorous activities and tire less readily than the white muscle
what is the relative fat content of dark meat?
associated with a higher fat content and is the part with the relatively higher content of triglycerides and cholesterol
how is poultry as a source of protein?
rich source of the essential amino acids, irrespective of the source (meaning which type of bird it comes from)
how does the meat of chickens and turkeys compare to duck and goose, fat-wise?
chicken and turkey are relatively low in fat compared to duck and goose
which types of fats are duck and goose higher in compared to chicken and turkey?
higher levels of MUFAs, while chickens and turkeys have higher levels of PUFAs
which is the most common MUFA in poultry?
oleic acid
which is the most common PUFA in poultry?
linoleic acid
what is the result of the higher PUFA content of chicken and turkey?
they are more prone to oxidative damage than ducks and geese
which factors does the composition of meat from poultry depend on?
age of the animal
species
diet
environment and level of activity
sex, etc.
how does the level of moisture in white and dark meat compare in chicken with skin?
light tends to be higher in moisture
how does the level of moisture in white and dark meat compare in turkey with skin?
dark tends to be higher in moisture
how does the level of protein in white and dark meat compare in chicken and turkey with skin?
light tends to be higher in protein
how does the level of fat in white and dark meat compare in chicken and turkey with skin?
dark tends to be higher in fat
how does the level of ash in white and dark meat compare in chicken and turkey with skin?
light tends to be higher in ash
how does the level of energy (kcal/100g) in white and dark meat compare in chicken with skin?
dark is significantly higher in energy (kcal/100g)
how does the level of energy (kcal/100g) in white and dark meat compare in turkey with skin?
dark is slightly higher, but they are almost identical
how does the level of moisture in white and dark meat compare in chicken and turkey without skin?
dark meat tends to be higher in moisture
how does the level of protein in white and dark meat compare in chicken and turkey without skin?
white tends to be higher in protein
how does the level of fat in white and dark meat compare in chicken and turkey without skin?
dark tends to be higher in fat
how does the level of ash in white and dark meat compare in chicken and turkey without skin?
light is slightly higher in ash
how does the level of energy (kcal/100g) in white and dark meat compare in chicken and turkey without skin?
dark tends to be higher in energy (125kcal/100g in dark meat, vs. 114-125kcal/100g in light meat for both)
duck and goose cooked with skin are much higher in which 2 factors?
fat is much higher, and energy is much higher
what is MDPM or MSPM?
mechanically deboned poultry meat, or mechanically separated poultry meat
how is the meat taken off the bones in MDPM?
first, boneless flesh is cut off the bones for consumer use
then, the meat still left on bones may be removed by high pressure treatments where the meat is held in a perforated tank (which is spun) in water and subjected to high pressure
the meat separates from the bones and passes out of the tank via the perforations, while the bones are left behind in the tanks
what can the MDPM separated by the tank be used for?
nuggets
sausage
hot dogs
bullion
soups
how large are the holes of the barrel sieve in MDPM?
protein found in the viscous or thicker albumen layer
highly phosphorylated glycoprotein so referred to as a phosphoglycoprotein
readily coagulated or denatured by heat, so participates in heat induced gelation/coagulation of egg proteins
what is ovotransferin?
this protein binds and transfers Fe
what does bacteriostatic mean?
acts to prevent bacterial reproduction by stopping DNA replication
what does bactericidal mean?
acts to kill bacteria by disrupting the cell membrane
what is ovomucoid?
much smaller glycoprotein, about half the size of ovalbumin
less viscous than ovalbumin and is found in the thin layer albumen
has heat resistance and foaming properties and accounts for the ability of egg white to form foams
which protein is responsible for the ability for egg white to form foams?
ovomucoid
what are the major carbohydrates found associated with ovomucoid?
glycosamine
mannose
galactose
sialic acid
what does lysozyme do?
proteolytic enzyme that acts to disrupt cell walls and thereby prevent microbial contamination
what is ovomucin?
large molecular weight glycoprotein, comparable in size to ovalbumin
thus it is also viscous and found in the thick layer or more viscous albumen layer
what do flavoproteins do?
bind riboflavin and participate in the electron transport chain
what is ovoinhibitor?
a broad spectrum serine protease inhibitor
what does avidin do?
can bind strongly to biotin and prevent it from transporting CO2 units
how many and which type of proteins are found in the albumen?
~0.03% phospholipids, triglycerides, and cholesterol
what are chalazae?
cord-like proteinaceous material that transfers the albumen layer from the egg shell membrane to the egg yolk membrane
the chalazae act to hold the egg yolk in its place within the egg structure and prevent it from moving around
what is it estimated that 2 eggs a day can provide?
20% of daily protein requirements (65-80g/day)
all essential amino acids
all essential FAs and high PUFA content, particularly α-linolenic acid
all known vitamins except C
very high in vitamin D
what percentage of the whole egg is egg white?
~63%
what kind of emulsion is an egg yolk?
oil-in-water
what percentage of the total egg is the yolk?
~27.5%
what is the total solids content of an egg yolk?
52-53%
what is the egg yolk surrounded by?
a membrane known as vitellin
where does the color range of an egg yolk come from?
depends on carotenoid content, usually from the animal's diet
what is the composition of an egg yolk?
mostly moisture, then 32% lipids, 16% protein
carb, vitamin, and mineral content is negligible
which proteins are present in the egg yolk?
2 types of lipoproteins (HDLP and LDLP)
lipid-free globular proteins
phosphoproteins
what is the density of LDLP?
density lower than that of water (~.98)
what are the major components of LDLP?
triglycerides (TGA), phospholipids (PL), and cholesterol
what is the density of HDLP?
greater than water, so >1
what are the major components of HDLP?
phospholipids (PL), triglycerides (TGA), with some amount of phosphates
what are livetins?
lipid-free globular proteins
fat free, devoid of phosphate groups
highly ionic and water soluble
they are the egg yolk equivalent of blood proteins in terms of function
what are phostivins?
phosphoproteins in the egg yolk
what are the amino acids present in the phosphoproteins?
predominantly serine residues (~50%)
and 90% of those are esterified with phosphate groups
what are the phospholipids found in egg yolk?
phosphotidyl choline (leuithin)
phosphotidyl ethanol amine (cephalin)
lysophosphotidyl choline
lysophosphotidyl ethanol amine
sphyngomylen
what is responsible for the emulsifying capacity of phospholipids?
they are amphiphilic, with both polar and non-polar sides
what are the types of triglycerides present in egg yolk?
SFA (saturated fatty acids)
MUFA
PUFA
which are the most common saturated fatty acids in egg yolk?
palmitic acid and stearic acid
what is the proportion of SFA in egg yolk?
fairly constant between 30-35%
what is the major MUFA in egg yolk?
oleic acid
what is the MUFA content in egg yolk?
ranges between 40-45%
what is the major PUFA in egg yolk?
linoleic acid
what is the PUFA content in egg yolk?
20-25%
what is the cholesterol content in an egg yolk?
ranges from about 1-2mg per 1g of egg yolk
which percentage of egg yolk cholesterol is in the esterified form, with the balance being in the free form?
about 15-16% is in the esterified form
what is the average diameter of an LDLP micelle?
~30nm
which is the most highly phosphorylated protein known to date?
phosvitin
where is 95% of the iron in eggs found?
in the yolk
lipids constitute what percentage of total egg yolk solids?
69%
how are the fatty acids of eggs derived?
synthesized through de novo lipogenesis
incorporation of dietary lipids
what are some deteriorative changes that occur in dried whole egg and egg yolk?
due to Maillard reaction (between cephalin and glucose) leads to discoloration and loss of palatability
why remove glucose prior to egg drying?
curtails the development of off-flavor during storage
how is desugaring of eggs done?
glucose is removed from egg or egg yolk through addition of glucose oxidase and catalase
what are designer eggs and what are some examples?
manipulating the diets fed to birds
omega-3 eggs are an example (can reach up to 500-600mg/egg, causes a darker yellow color to the yolk)
other examples include vitamin A and E enriched eggs
studies are going on to increase the content of what in eggs?
essential minerals such as selenium, iodine, chromium through supplementation of hen feed
what is the major pathogen of concern in eggs?
Salmonella enteritidis (SE)
how does SE contaminate eggs?
from the outside of the shell following contamination in the oviduct or from the feces
may enter the egg in the oviduct prior to the laying down of the egg shell, although there is limited evidence for this route of contamination
what is an effective safeguard against SE contamination?
maintenance of eggs at refrigeration temperatures throughout processing
*TRUE OR FALSE: egg shell is primarily calcium apatite.
FALSE
calcium carbonate
*describe in detail the compositions of egg yolk lipids
FA composition in egg yolk is typically 30-35% SFA, 40-45% MUFA, 20-25% PUFA
the amount of SFA, primarily palmitic (16:0) and stearic (18:0), is fairly uniform and changes little with changes in the dietary fats
in contrast, linoleic acid content increases and oleic acid decreases when the level of dietary PUFA is elevated (this aspect is of particular interest for the improvement of the nutritional value of egg yolk)
*TRUE OR FALSE: storage lipids in muscle are primarily fatty acid triesters of glycerol and the most prevalent fatty acid is oleic acid.