A simple and accurate objective test for monitoring lipid oxidation in poultry products is needed. Thiobarbituric acid (TBA) values of cooked poultry meat were determined by a distillation method and by a modified extraction method. Perchloric acid was used in the extraction method to release TBA reactive substances from the meat. The maximum absorption wavelength of the TBA-malonaldehyde complex was 531 nm. The TBA values for cooked chicken and turkey were highly correlated (r = .91) for both the extraction and distillation methods. Sensory scores of warmed-over flavor in precooked poultry were highly correlated with TBA values in both the distillation (r = .83) and extraction (r = .85) methods. Results indicate that the extraction method is faster, easier to perform, and as accurate as the distillation method for monitoring lipid oxidation in poultry.

Turkey breast or thigh muscle was mixed with 2% pure salt, rock salt, or pure salt plus 50 ppm of one or a combination of copper, iron or magnesium. EfJicacy of 2 antioxidants was tested. Lipid oxidation was monitored during refrigerated and frozen storage of raw and cooked turkey by the thiobarbituric acid (TBA) test. TBA results indicated that the most signijicant prooxidant effect was caused by salt plus Cu2+ and Fe2+ followed by salt plus Fe3+ or Cu2+ alone. Tenox 6 was an effective antioxidant in the presence of copper and iron ions. Thigh meat was more susceptible to oxidation than breast meat. Cooking had a signijicant prooxidant effect as measured by TBA.

SummaryThe effect that changes in composition which occur in milks possessing high cell counts have on milk lipolysis has been investigated. High cell counts were produced either by intramammary infusion of Escherichia coli endotoxin or Streptococcus agalactiae or by addition of washed cells which were isolated from milk obtained from quarters infused with endotoxin. Free fatty acid levels in milk were measured in terms of acid degree value (ADV) either as initial ADV measured immediately after milking or ADV developed after a prescribed incubation period.There was an increase in initial ADV after the infusion either of endotoxin or of Str. agalactiae relative to a control quarter. This increase appeared to be associated with changes in cell count, but in absolute terms the influence of cells on ADV became less as cell count increased. Neither type of infusion had any effect on lipoprotein lipase activity. The addition of washed cells to normal milk resulted in an increase in developed ADV, but the increment was not as large as that produced by the addition of 1% blood serum. When cream and skim-milk from endotoxin-treated quarters and control quarters were mixed in different combinations with and without additional cells, developed ADV was higher in those samples containing endotoxin cream and those with added cells. Milk from a quarter treated with endotoxin was diluted with its own skim-milk to produce different cell counts and ADV was determined after various time intervals at 4 and 37 °C. Lipolysis increased with increasing cell count, but a depression in lipolytic rate was noted after incubation for 6 h at 4 °C and 20 min at 37 °C.The proportion of skim-milk lipoprotein lipase activity in milk serum was larger both in milks possessing high cell counts and in normal milk adjusted to between 5 and 20 mM-NaCl by addition of solid NaCl. These levels of NaCl inhibited lipolysis.The possible direct and indirect effects of high cell count on milk lipolysis are discussed.

We investigated the effect of a non-mammalian omega-3 desaturase in a mouse hepatocarcinogenesis model. Mice containing double mutations (DM) in c-myc and TGF-α (transforming growth factor-α), leading to liver neoplasia, were crossed with mice containing omega-3 desaturase. MRI analysis of triple mutant (TM) mice showed the absence of neoplasia at all time points for 92% of mice in the study. Pathological changes of TM (TGFα/c-myc/fat-1) mouse liver tissue was similar to control mouse liver tissue. Magnetic resonance spectroscopy (MRS) measurements of unsaturated fatty acids found a significant difference (p<0.005) between DM and TM transgenic (Tg) mice at 34 and 40 weeks of age. HPLC analysis of mouse liver tissue revealed markedly decreased levels of omega-6 fatty acids in TM mice when compared to DM (TGFα/c-myc) and control (CD1) mice. Mass spectrometry (MS) analysis indicated significantly decreased 16:0/20:4 and 18:1/20:4 and elevated 16:0/22:6 fatty acyl groups in both GPCho and GPEtn, and elevated 16:0/20:5, 18:0/18:2, 18:0/18:1 and 18:0/22:6 in GPCho, within TM mice compared to DM mice. Total fatty acid analysis indicated a significant decrease in 18:1n9 in TM mice compared to DM mice. Western blot analysis of liver tissue showed a significant (p<0.05) decrease in NF-κB (nuclear factor- κB) levels at 40 weeks of age in TM mice compared to DM mice. Microarray analysis of TM versus DM mice livers at 40 weeks revealed alterations in genes involved in cell cycle regulation, cell-to-cell signaling, p53 signaling, and arachidonic acid (20:4) metabolism. Endogenous omega-3 fatty acids were found to prevent HCC development in mice.

The effects of various heat treatments on warmed-over flavor (WOF) in ground chicken breast meat were examined. WOF was measured by thiobarbituric acid test and taste panel. Integral temperature-time history functions (TTH) were used to quantify constant and variable temperature-time heat treatments. The effect of processing on WOF was modeled as a modified first-order kinetic absolute reaction. A reaction threshold temperature of 74°C and an activation energy of 15,000-20,000 Cal/g-mole were calculated. The accumulated TTH value above 74°C was found to have a major effect on WOF development. WOF in precooked chicken breast meat can be controlled by choice of processing conditions.