Page 239 - Natural Antioxidants, Applications in Foods of Animal Origin

218 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir where the coefficients 25 and 1.2 are dilution factors,

A is the absorbance of the reacted sample,
1
A is absorbance of the blank,
2
A is absorbance of unreacted sample,
0
m is the mass of sample.
Although the coefficient of variation (C of V) for p-AV is relatively
precise measurement, it can vary depending on the species source and
processing methods in rendering the fat. p-anisidine analysis is a valuable
measurement technique for measuring oxidation; however, correlation to
sensory evaluation has not been established.

6.2.3 TOTAL OXIDATION (TOTOX) METHOD

A single molecule of a hydroperoxide can produce a variety of different
compounds with varying chain lengths and levels of unsaturation during
oxidation. To analyze for a single product of oxidation may not enough
information. p-AVs and PVs can be combined (Equation 6.9) to provide
more information about the oxidative status of meat products.

TOTOX = 2PV + p-AV (6.9)

PVs and p-AVs (a dimensionless value that indicates the level of
non-volatile secondary oxidation products) are expressed in different
units, the formulation and the significance must be derived empirically.
Some food scientists have suggested the using thiobarbituric acid reac-
tive substance (TBARS) values to replace the p-AV values for calculating
TOTOX values (Wanasundara & Shahidi, 1995). The justification for the
formula 2PV + p-AV is based on an increase of one PV unit corresponding
to an increase of two p-AV units (Shahidi et al., 2002). Integrating PVs
and p-AVs into one equation for the purpose can result in an accumula-
tion of errors (i.e., uncertainty) by combining values derived from two
measurement techniques into a single numerical value. The accumula-
tion or propagation of errors can be estimated for TOTOX, assuming the
values for PV and p-AV are normally distributed, independent, and errors
are small. The propagation of errors (ϵ) for TOTOX can be calculated
using Equation 6.10.