Sensory and chemical analysis of cooked porcine meat patties in relation to warmed-over flavour and pre-slaughter stress

Two independent sensory profiles were carried out to evaluate warmed-over f lavour (WOF) development in cooked, chill-stored and reheated pork patties. The patties were derived from the Musculus semimembranosus of animals subj ected to different pre-slaughter stress treatments. All patties were stored in oxygen permeable bags at 4 degreesC for 0, 1, 2, 3 and 5 days to facili tate WOF development. In addition, thiobarbituric acid reactive substances (TBARS), conjugated dienes, pH, water content, total lipids and the fatty a cid compositions of phosphatidyl choline (PC), phosphatidyl ethanolamine (P E) and total lipids, were measured in the cooked meat patties. A data analy tical strategy involving Analysis of Variance-Partial Least Squares Regress ion (ANOVA-PLSR), to determine relationships between the design variables ( WOF and pre-slaughter stress) and the sensory-chemical data, and PLSR to el ucidate predictive links between the sensory and chemical data was utilised . WOF was found to involve the development of lipid oxidation derived nuanc e off-flavour and odour notes, e.g. rancid-like flavour and linseed oil-lik e odour, in association with a concurrent decrease in cooked pork meat-like flavour. The reduction in "meatiness", over the initial days, 0-2 of WOF d evelopment was attributed to the degradation of both, unstable sulfur-conta ining amino acids in meat proteins and sulfur-containing "meaty" aroma comp ounds. Whereas, at the later days, 3-5 of WOF development the "meaty" loss was ascribed to perceptual masking by lipid oxidation products. TBARS and c onjugated dienes were found to be significant (P<0.05) predictors of the se nsory terms related to the lipid oxidation aspect of WOF. Whilst the polyun saturated fatty acid (PUFAs) contents of PE, PC and the total lipids were f ound to decrease with WOF development, reflecting their loss in lipid oxida tion reactions. The sensory variation related to pre-slaughter stress appea red to be distinct from WOF variation and was described by a sour to sweet taste continuum. However, interactions were noted that indicated increasing pre-slaughter stress resulted in a decreased sensory perception of WOF. Mo reover, pH and water content were found to significantly (P<0.05) predict t he sensory effects resulting from pre-slaughter stress. (C) 2001 Elsevier S cience Ltd. All rights reserved.