Peroxide value quality indicator

Mustakas et al. (46) evaluated the effects of extruder-processing on nutritional quality, flavor, and stability of the product in an attempt to describe extruder conditions which would be acceptable in all three respects. Urease activity was used as an estimation of trypsin inhibitor activity thus the area between the two urease curves in Figure 2 indicates processing conditions which strike a balance between too much and too little heat treatment, showing optimal nutritional quality. Using the flavor and peroxide value isograms, processing conditions may be chosen such that acceptable flavor and stability may also be achieved. 

Iodine, colorimetric determination of amylase using, 689-692 Iodine value, lipid composition canola oil, 474 (table) oil quality indices, 467-469, 475-477 lodometric titration, determination of peroxide value, 518-519 Ionization techniques, in mass... 

Those for crude oils include the free fatty acids (FFA), iodine value (IV), saponification value (SV), refractive index (RI), specific gravity (SG), unsapo-nifiable matter (US), and moisture plus impurities (M I). These are intended to give a quick impression of the authenticity of the oil and the likely losses in refining. For refined oils, the values also usually include the colour, peroxide value (PV), slip melting point (SMP) and solid fat content (SFC), if appropriate. These are indications of quality and behaviour in use. As the SFC test relies on nuclear magnetic resonance, these values are also known as NMR or N values. The Malaysian standard for crude and refined CNO (MS 1987) is shown in Table 6.7 and the Codex (2001) draft standard in Table 6.8. 

Wang and Johnson (2001) reported on test measurement methods that were major indicators of soybean oil quality. These tests included peroxide value, anisidine value, FFA content, phospholipid content, total tocopherol content, oxidative stability index, color, and moisture content. For soybean meal, they reported on urease activity, protein dispersibility index (PDI), rumen bypass or rumen undegradable protein, trypsin inhibitor activity, moisture content, residual oil content, protein content, fiber content, color, amino acid profiles, and protein solubility under alkaline (KOH) conditions. 

The elevated temperatures used during deodorization are sufficient to initiate some chemical reactions both on the oil and on some of its minor components. Hydroperoxides, frequently the precursors of off-flavor development, are completely broken down during the deodorization process, so the peroxide value of a freshly deodorized oil is zero. Values other than zero frequently indicate the presence of a small air leak in the equipment, normally in the post-deodorization cooling stages. Volatile products of this thermal decomposition are normally stripped from the oil during the deodorization process, but any nonvolatile fragments will stay with the finished oil, possibly with detrimental effects on its quality. 

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