Cp. Tan et Ybc. Man, Differential scanning calorimetric analysis of edible oils: Comparison of thermal properties and chemical composition, J AM OIL CH, 77(2), 2000, pp. 143-155
The thermal profiles of 17 edible oil samples from different plant origins
were examined by differential scanning calorimetry (DSC). Two other confirm
atory analytical techniques, namely gas-liquid chromatography (GLC) and hig
h-performance liquid chromatography (HPLC), were used to determine fatty ac
id (FA) and triacylglycerol (TAG) compositions. The FA and TAC compositions
were used to complement the DSC data, iodine value (IV) analysis was carri
ed out to measure the degree of unsaturation in these oil samples. The DSC
melting and crystallization curves of the oil samples are reported. The con
trasting DSC thermal curves provide a way of distinguishing among these oil
samples. Generally, the oil samples with a high degree of saturation (IV <
65) showed DSC melting and crystallization profiles at higher temperature
regions than the oil samples with high degree of unsaturation (IV > 65). Ea
ch thermal curve was used to determine three DSC parameters, namely, onset
temperature (T-o), offset temperature (T-f) and temperature range (differen
ce between T-o and T-f). Reproducibility of DSC curves was evaluated based
on these parameters. Satisfactory reproducibility was achieved for quantita
tion of these DSC parameters. The results show that T-f of the crystallizat
ion curve and T-f of the melting curve differed significantly (P < 0.01) in
all oil samples. Our observations strengthen the premise that DSC is an ef
ficient and accurate method for characterizing edible oils.