Flavor is the predominant characteristic of meat responsible for consumer preferences. One of the most important causes of flavor deterioration in meat is lipid oxidation that begins almost instantly after slaughter (Gray and Pearson, 1994). Autoxidation of lipids is carried out by a free radical chain reaction. The initial step in this reaction is the formation of peroxide that further degrades into several reactive compounds including malonaldehyde (MA) (Ranken, 1989; Raharjo and Sofos, 1993). These secondary products are responsible for undesirable or "rancid" flavors (Shahidi, 1994).
Due to its non-homogeneous nature there are no good methods to evaluate the lipid oxidation of meat. Currently, one of the most common analytical methods for determining lipid oxidation in meat is the TBA assay, which measures a TBA-MA complex with an absorbance maximum at 530 nm (Nawar, 1996). The TBA method has certain limitations in food systems. TBA non-specifically reacts with compounds such as sugars, ascorbic acid, and non-enzymatic browning products often present in foods (Decker et al., 1998). Another potential drawback to the TBA method is that MA is not always present in all food systems, which could produce biased results (Gray, 1978).
Another common analytical method of determining lipid oxidation is the PV. The assay for peroxides is the most direct measurement of lipid oxidation (Fielder, 1974). The AOCS method of determining PV requires a multi-step titration and a 1 min incubation that has been described as insufficient (Lezerovich, 1985; Takagi et al., 1978). The AOCS method also is subject to inherent experimental error due to the subjectivity in visual endpoint determination (Fielder, 1974). Some colorimetric peroxide methods have been developed to minimize the subjectivity in visual endpoint determination, including the measurement of Cadmium iodide (Takagi et al., 1978) or triiodide in the UV range (Lezerovich, 1985; Lovaas, 1992). However, these methods have the disadvantages of requiring the use of expensive or toxic compounds (Takagi et al., 1978) and result in the generation of unstable or hazardous ions (Lezerovich, 1985; Lovaas, 1992).
The purpose of this research was to develop a rapid, sensitive, and reproducible spectrometric method of determining peroxide values, incorporating the advantages and eliminating many disadvantages of the TBA and AOCS methods.