Meat, Fish, Eggs, Alternative Proteins Flashcards
organic egg
from birds that are fed special organic feed that is not treated with chemical pesticides or fertilisers.
the birds are also not treated with growth hormones or given antibiotics
lecithin egg
found in egg yolk natural emulsifier (explain emulsification underlying principle)
cold smoking fish
involves subjecting a fish to smoke from wood chips
the chemicals creosote and formaldehyde in the smoke prevent microorganism growth on the fish flesh
temp doesnt go beyond 27 degrees so fish must be cooked further
hot smoking fish
same as cold but temp is gradually increased to approx 80 degrees
doesnt require further cooking
effects of cooking on proteins in meat
proteins coagulate causing the fibres to shrink at 40-50 degrees
collagen converts to gelatine, making meat more digestible as the fibres loosen and fall apart
nutritive value of fish
HBV protein - myosin, actin
oily fish - polyunsaturated fat, omega 3s eg EPA and DHA
no fat in white fish
lack carbs - any glycogen is converted to lactic acid when caught
b group vitamins B6 and B12
oily and white fish Vit A and D
minerals - small amount iodine, zinc, phosphorous
shellfish iron
canned fish calcium as bones are eaten
water content varies on type (higher the fat, lower the water)
main causes of fish spoilage
oxidative rancidity
enzymes
bacteria
oxidative rancidity fish spoilage
oils in oily fish react with oxygen in the air
oxygen combines with the carbons in the double bond of the unsaturated fatty acid chain, causing the fish to turn rancid
enzymes fish spoilage
naturally present enzymes in fish cause its flesh to deteriorate, even at low temperatures.
can be slowed by placing on ice or in fridge
bacteria fish spoilage
when fish are caught they struggle frantically, using up the glycogen in their muscles and liver
this results in little glycogen being left to convert to lactid acid to preserve the fish, which in turn causes rapid deterioration by bacterial action
produces a strong smelling nitrogen compound, trimethylamine
nutritional significance of eggs
HBV protein - ovalbumin and globulin fat - saturated in yolk. dispersed as a fine emulsion due to the presence of lecithin yolk contains cholesterol carbs- lacking vitamins- B1, B2, B3 , B12 yolk has vit A,D,E,K minerals- calcium, phosphorous, zinc, sulphur, non haem iron water- high content
properties of eggs
aeration
coagulation
emulsification
aeration eggs
when eggs are whisked, protein chains unfold and air bubbles form
protein chains entrap air, creating a foam
whisking eggs also creates an amount of heat that begins to set the egg albumin, creating a temporary foam
it will collapse unless heated to coagulate and set as a permanent foam
culinary use: meringue, souffle
coagulation eggs
when eggs are heated, protein chains unfold, straighten and bond together around small pockets of water
egg whites- 60 degrees
yolk-68 degrees
culinary use: cooking eg fried egg, thickening eg custard
emulsification eggs
lecithin in egg yolk is a natural emulsifier
has the ability to join two immiscible liquids
underlying principle of emulsification
culinary use: mayonnaise, hollandaise sauce
nutritional significance of meat
HBV protein- myosin, collagen, actin fat - saturated visible or invisible depends on type eg pork has more than beef carbs- lacking vitamins- B1, B2,B3, B6,B12 minerals- iron, zinc, sulphur, phosphorous water- depends higher the fat, less water
factors causing toughness in meat
age- older have more connective tissue, connective tissue is stronger, muscle fibres are longer and thicker
activity- meat from active parts of the animal eg leg is tougher, as it develops longer muscle fibres and more connective tissue
methods of tenderising meat
mechanical breakdown- eg pounding with meat hammer breaks down fibres into smaller shorter length, tenderising meat
marinating- in a mix of acid, salt, herbs, spices, fruit or dairy breaks down fibres, tenderising meat
meat tenderisers eg papain - break down fibres
process to extend shelf life of meat
freezing
meat is deboned and some fat is removed. it can then be frozen by commercial methods eg blast at -30 or home freezing at -25
no effects on colour, taste, texture
microorganisms deactivated
some loss of b group vit due to drip loss when thawed
freezer burn may occur if packaging is damaged
methods of quality assurance in egg production
all feed is heat treated for hens
eggs carry best before date, house code and logo
incoming hens must be certified as salmonella free
dry method of cooking fish
baking cooks by convection currents fan oven evenly distributes heat steam produced by the food prevents drying out enhances flavour crisp finish eg breaded fish
moist method of cooking fish
steaming cooks by steam rising from boiling water food doesn't touch the water steam circulates around the fish digestible but can lack flavour
