What percent of muscle is fat
5-10%
what is contained in ‘ash’
bone
vitamins
mineral
carbohydrates
general structure of glycerol
3 carbon chains with a hydroxyl group off each carbon
where do fatty acids attach to on the glycerol backbone
the OH group
2 most common FAs in meat, and their makeup
Oleic-C18:1 n9
Steric-C18:0
what is the gamma carbon
the carbon furthest from the carboxyl group
what type of fatty acid is considered essential?
omega 3
what is released when the ester bond is formed
H2O
what type of FA are generally in phospholipids? why?
unsaturated
unsaturated increases fluidity
length range of FAs in mammals? what are the most common chain lengths?
10-24
-most common is 16 and 18 carbons
why are odd numbered FA chain lengths rare
carbons are often deposited in pairs
what FA chain lengths generally have gamma 3 double bonds
C20 and C22
how does chain length and degree of saturation impact melting point of FAs
-as chain length increases so does melting point
-as saturation increases so does melting point
which type of fat(external or internal) has a higher melting point? why?
Internal fat
it has to stay solid at a higher temp in the body
what meat defect does oxidation of fats lead to
rancidity
why is it beneficial that myoglobin oxidation occurs before lipid oxidation
it gives a visual cue that the meat is going bad before it is actually unsafe to eat
what is WOF? how does it occur
warmed over flavor
-rapid onset of rancidity in cooked food when reheated
3 main steps of lipid oxidation
Initiation: formation of free radical
Propagation: free radical attacks DB forming a new free radical
Termination: end of lipid oxidation
what is often formed during propagation when a free radical steals an electron
a nonanal(a carbon aldehyde) due to breaking off part of the fatty acid
lipid oxidation vs lipid thermal degradation
LO: most often associated with fresh meat
LTD: warmed over flavor
what is the basic result of lipid oxidation propagation
numerous short chain carbons
(aldehydes, alcohols, ketones, acids, and esters-product depends on location of DB)
catalysts of lipid oxidation
lead
copper
myoglobin
hemoglobin
methods of lipid oxidation termination
-2 radicals interact and share electrons
-an antioxidant donates an electron to the free radical
-an antioxidant chelates the prooxidant making it unable to continue reacting
what is a common substance that binds prooxidants to stop lipid oxidation
phosphates
