Evaluation of pork backfat firmness and lard consistency using several different physicochemical methods

A total of 96 pigs; were fed on a control diet (barley, wheat, soybean meal) or the control diet supplemented with one of six fats, differing in saturated (SFA), cis- and trans-monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) content, in order to produce backfat widely differing in fatty acid composition. In addition to fatty acid composition, firmness was measured, by means of a puncture test, in the intact outer backfat layer and in lard extracted from the outer layer. Melting behaviour and solid fat content (SFC) were determined by differential scanning calorimetry and crystallisation time with a Rapid Interesterification Control-Box. Regression analyses revealed that all consistency traits were mainly dependant on SFA content, particularly stearic acid. Cis-MUFA were the next most decisive for crystallisation time and SFC. The prediction of firmness and SFC at 0degreesC was improved when the proportion of PUFA was also considered. The stearic to linoleic acid ratio provided the best prediction of lard firmness. It was concluded that MUFA and PUFA exert specific effects on the different consistency characteristics and not only PUFA but also MUFA should be considered in feeding recommendations for growing-finishing pigs when lard consistency is to be improved. (C) 2004 Society of Chemical Industry.