Optimization of procedures for oil extraction from animal tissue

Oil was extracted from chicken and pork fat discards by microwave assisted extraction and soxhlet extraction for comparison. Protease enzyme and pulsed electric field were used as a pretreatment prior to extraction by either soxhlet or microwave assisted extraction by hexane. Conditions for both the enzyme pretreatment and the microwave extraction were optimized for the extraction of the oils from the discards. The fat discards were pretreated with papain enzyme in a phosphate buffer solution (pH 7.0) and incubated at 45°C in a water bath and incubated at various time intervals (30 min, 1 h, 2 h and 3 h). Enzyme pretreatment at 2 h produced the highest oil yield increase of 20.1% when compared to the control samples (P=0.0003) in chicken samples and an oil yield increase of 16.6% in comparison to control samples (P=0.0179) in pork samples. There was a decrease in oil yield at 3 h and no significant difference in oil yield when compared to control in both chicken samples (P=0.217) and pork samples (P=1.0000). Optimization of microwave assisted process shows that microwave irradiation for 7.5 min produced the best oil yield and was the most effective in oil extraction from the animal discards. There was no significant difference in oil yield produced when the irradiation time was increased to 10 min, 12.5 min, and 15min. The results obtained from optimization of microwave assisted extraction were comparable to those obtained by soxhlet extraction for 3 hr. There were significant difference between oil yield obtained from both extraction methods (P=<0.05). There were no differences in the FAME profile when compared to the literature. Pulsed electric field pretreatments were carried out on pork samples at electric field strength of 2 kV cm -1, 4 kV cm-1, 6 kV cm-1. The oil yields obtained were compared to values obtained from control samples after extraction using microwave assisted extraction for 3 min. Pulsed electric field at 4 kV cm-1 produced an oil yield increase of 6.79% and significantly different (P=0.0344) compared with control samples. There were no significant differences between oil yield at 2kV and control samples (P=1.000). At pulsed electric field strength of 6 kV cm-1 there was a decrease in oil yield. The oil yields obtained from pulsed electric field pretreament were compared with that obtained by soxhlet extraction. Pretreatment at 4kv cm-1 gave an oil yield increase of 6% (P=0.1411). The quality assessment of the oil extracted with PEF pretreated samples showed no effect of PEF on the quality of the oil. There were no significant differences in the hydroperoxide and p-anisidine values within the pretreatments and the control samples. PEF pretreatment had no effect on the fatty acid methyl ester (FAME) profiles of the oil.