Lipid autoxidation in freeze-dried meats

Abstract

The rapid absorption of oxygen and appearance of off-odors in freeze-dried meats indicate that oxidative deterioration occurs.However, no peroxides were found and changes in spectral absorption of the fat, thiobarbituric acid reactive substances, and reducing capacity of the dried meats were small and could not be correlated with the absorption of oxygen. Of the several objective methods studied, oxygen absorption was the only one that could be used to indicate oxidation. Freeze-dried beef and chicken have been fractionated into their lipid and nonlipid components. The absorption of oxygen by the isolated fractions has been compared to that of the whole tissues. Autoxidation of freeze-dried meats takes place in two stages. The protein-bound lipids autoxidize first, without an induction period, and their initial rate of autoxidation decreases with time. After a period of lower oxygen absorption, the free glyceride fat begins to autoxidize in the autocatalytic manner characteristic of autoxidation in isolated glyceride fats.4 utoxidation of lipid is a serious cause of deterioration /A in freeze-dried meat. Lea (1943) recognized two types of defects in stored freeze-dried meats: a tallowy or oily flavor due to fat oxidation; and a mealy defect ascribed to deterioration of nonfat components.In studies with freeze-dried beef, Tappel ( 1956) and El-Gharbawi and Dugan (1965) found that protein-bound lipids autoxidized readily, whereas the free glyceride fat was very stable. In addition, Tappel (1956) reported that protein could account for 50 to 100% of the total oxygen absorbed by freeze-dried beef. However, Lea et al. (1958) observed that the residual protein of defatted herring meal did not oxidize readily.

Effect of Water Activity on Lipid Oxidation and Protein Solubility in Freeze‐dried Beef during Storage

“…There was no difference in TBARS@532 between the 2 package types at 49 ЊC, or between 2 temperatures within air-permeable packaging (p > 0.05; Table 1). These results are consistent with previous observations in food systems (Chipault and Hawkins 1971;Melton 1983;Wilkinson and others 2001). Since no significant difference was attributed to package type, data from the 2 package types were combined to assess the relationship among a w, TBARS@450, and protein solubility.…”

Fluorescence kinetics of soybean flour oxidation

“…These observations suggest that peroxide and TBA values are not appropriate for determining oxidative deteriora-tion in soybean flour. Previous studies also have suggested that peroxide and TBA values cannot always be correlated quantitatively with reaction extent, as the oxidation products can further react with some food constituents and cause intrinsic fluorescence changes (4,18,19).…”

Amine‐malonaldehyde condensation products and their relative color contribution in the thiobarbituric acid test

“…Similar results have also been observed in this laboratory during storage experiments with frozen fish. In freeze-dried meats the TBA values were low and could not be correlated with the appearance of off-odors or the absorption of oxygen (4), and recoveries of malonatdehyde (M) by distillation methods ranged between 70-95% (5). Reasons for the low recoveries of M have occasionally been advanced.…”