Page 228 - Natural Antioxidants, Applications in Foods of Animal Origin

Methods and Their Applications for Measuring 207
VetBooks.ir 3. Data from the analysis are minimally influenced by interfering

substances.
4. Analytical data vary predictably over time.
5. Data are relatable and relevant to the industry segment.
6. Results from the analysis are correlated to sensory (flavor, aroma,
and/or color) analysis.
7. Method and technique are easy to use and rapid.

For all methods, sample preparation (collecting samples, grinding,
mixing, etc.) is critically important for minimizing errors and uncertainty.
Solvent extraction of lipids from meat tissues is of particular importance
because solvent selection is critical for complete recovery of the fat for anal-
ysis (triacylgylcerides (TAG) and the unsaturated phospholipids (PL)). Lipid
oxidation is initiated in the PL fraction and then proceeds to involve lipids in
the TAG fraction. Therefore, complete extraction of TAGs and PL fractions
will provide the most accurate assessment for the extent of oxidation.
The solvent systems recommended in the procedures described in this
chapter for extracting TAG and PL lipid fractions from meat tissues have
been determined experimentally by applying the following principles. .

1. Extraction efficiency of the solvent system.
Solvent system (pairing a polar component, with a nonpolar compo-
nent) is based on the distribution coefficient, K for a given meat
matrix.

solubility in lipid phase
K = solubility in aqueous phase (6.1)

The larger the coefficient K (greater than 1), the greater the yield of fat
containing products from lipid oxidation in the sample.

2. Amount of the solvent(s) needed.
The less solvent that is used the better, in the case of solvent extracted
lipids containing secondary oxidation products, less is more. For
example,

1
Fraction of lipid extracted = (1 ) / (( V+ V s m × )) (6.2)
n
nK