Impact of lipid degradation processes, and supercritical carbon dioxide extraction on flavor characteristics of lard.

摘要

The Lipase E5000 resulted in higher percent free fatty acids (FFA) when compared with the other enzymes at both concentration levels and for each incubation period (P 0.05). The 1.5% concentration was usually more effective in liberating FFAs than the 1.0% concentration, and longer incubation periods with each enzyme increased the free fatty acid value. Lard lipolysates were generated using four different lipases, i.e. Microbial Lipase 50, Lipase E5000, Pancreatic Lipase 24, and Esterase/Lipase 10X, by an invert emulsion technique. The final concentrations of taurocholic acid, water, and enzyme in the reaction mixture were 10mM, 12.5% and 1.5%, respectively, with an incubation period at 12 hours. The thermal degradation process used three temperatures (100, 150 or 200°C) and three heating times (10, 60 or 360 min).; FFA profiles revealed that C18:1 was the predominant FFA in both lipolysates and thermally degraded lard. Lipase E5000 generated the highest total FFA concentrations (P 0.05). Aldehydes, alkanes, saturated monocyclics and, in particular, alcohols were the major volatiles found from lipolysates, while the largest classes of volatiles of thermally degraded lard were alkanes, alkenes, aldehydes, enals, acids, branched alkanes, branched alkenes, and saturated mono- and dicyclics. Heating lard at high temperatures for long periods of time generated high intensities of the following sensory descriptors: oily, canola oil, corn oil, and overall intensity. On the other hand, mild temperature and enzymatic degradation, with the exception of pancreatin lipase, tended to produce lard that had primarily buttery, sweet corn, and sweet sensory characteristics. Lipolysate generated from pancreatin lipase generated a high intensity of a burnt sensory attribute.; Lard was extracted with SC-CO₂ at each of four pressures (8, 20, 35, and 50 MPa) and at each of three temperatures (40, 50 and 60°C). Obtained extracts were analyzed for their titratable FFA, FFA, and volatile profiles. Titratable FFA of SC-CO₂ extracts increased with increasing extraction pressures and temperatures (P 0.05). Retrograde behavior of lipid solubility was observed around 35 MPa. Recovery of the main fatty acids of lard, including C16:0, C18:1, and C18:2, increased with increasing extraction pressures and temperatures (P 0.05). Conversely, short and medium chain free fatty acid concentrations increased with decreasing extraction pressures and temperatures (P 0.05).; Total volatiles were concentrated over controls by 5–150 fold depending on extraction conditions. In addition to total volatiles, the aldehydes, enals, alkanes, alkenes, branched alkanes, branched alkenes, and aromatic compounds were affected by extraction conditions (P 0.05). Decreasing density of SC-CO₂ was found to be a primary function in increasing concentrations tentatively identified volatiles.