Beef lipid degradation in stew with and without vegetables

The moisture and total lipid levels and concentrations of cephalin, lecithin, and phospholipid fatty acids of beef and the 2-thiobarbituric acid (TEA) number and psychrophilic bacterial count of beef stew were analyzed as a function of Process, Treatment and Storage. The effect of cooking on these parameters was also determined. Two replications were run, with each replication being composed of cubed beef from the biceps femoris and semitendinosus muscle from a single side of "A" maturity steer carcasses. The two Processes were beef cooked in a stew and stored in a polyethylene container at 5 to 6° (p1) and beef cooked in a stew and stored in a barrier bag at 0°C (P2). The 4 Treatments were beef cooked alone (Tl), with onions (T2), with carrots (T3) and with onions and carrots (T4). Stews in PI were stored for 0,2 and 4 days and stews in P2 were stored for 0,2 and 4 weeks. Cooking decreased the moisture content of the beef from 68.5 to 59.7%, the cephalin content by 39%, the lecithin content by 21% and most of the phospholipid fatty acid concentrations as well as the fatty aldehydes levels in the phospholipids. The major degradation products of cephalin and lecithin were the lyso-compounds. Lecithin content was not affected (P<0.05) by Process, Treatment or Storage; cephalin content was not affected by Process or Storage; and fatty acid concentrations were not affected by Treatment or Storage. Beef from PI stews had more 16:0 fatty acid than that from P2 stews, and cephalin content was higher in beef that had been cooked in stews with carrots. PI stews had a larger TBA-number (P<0.05) than P2 stews, and the TBA-number of P1 stews increased linearly across 4 days Storage. The TBA-number was not affected (P<0.05) by Treatment for any of the stews and did not change significantly across 4 weeks Storage in P2 stews. The log count of psychrophilic bacteria in the stews was not affected by Process, Treatment or Storage.