Lard being an edible fat could be used in different forms in food systems. In this study, composition and thermal analysis of lard stearin (LS) and lard olein (LO) were undertaken to determine some common parameters which would enable their detection in food. A sample of native lard was partitioned into LS and LO using acetone as solvent and the fractions were compared to the original sample with respect to basic physico-chemical parameters, fatty acid and triacylglycerol (TAG) composition, and thermal characteristics. Although LS and LO displayed wider variations in basic physico-chemical parameters, thermal properties and solidification behavior, they do possess some common characteristic features with regard to composition. In spite of the proportional differences in the major fatty acids, both LS and LO are found to possess extremely high amount of palmitic (C16:0) acid at the sn-2 positions of their TAG molecules. Similar to native lard, both LS and LO contained approximately equal proportions of TAG molecules namely, linoleoyl-palmitoyl-oleoyl glycerol (LPO) and dioleoyl-palmitoyl glycerol (OPO). Hence, the calculated LPO/OPO ratio for LS and LO are comparably similar to that of native lard.
A study was carried out to determine the physicochemical characteristics of the oil derived from papaya seeds of the Hong Kong/Sekaki variety. Proximate analysis showed that seeds of the Hong Kong/Sekaki variety contained considerable amount of oil (27.0%). The iodine value, saponification value, unsaponifiable matter and free fatty acid contents of freshly extracted papaya seed oil were 76.9 g I2/100g oil, 193.5 mg KOH/g oil, 1.52% and 0.91%, respectively. The oil had a Lovibond color index of 15.2Y + 5.2B. Papaya seed oil contained ten detectable fatty acids, of which 78.33% were unsaturated. Oleic (73.5%) acid was the dominant fatty acids followed by palmitic acid (15.8%). Based on the high performance liquid chromatography (HPLC) analysis, seven species of triacylglycerols (TAGs) were detected. The predominant TAGs of papaya seed oil were OOO (40.4%), POO (29.1%) and SOO (9.9%) where O, P, and S denote oleic, palmitic and stearic acids, respectively. Thermal analysis by differential scanning calorimetry (DSC) showed that papaya seed oil had its major melting and crystallization transitions at 12.4°C and -48.2°C, respectively. Analysis of the sample by Z-nose (electronic nose) instrument showed that the sample had a high level of volatile compounds.