Differential Thermal Analysis of Edible Oils and Fats. VIII.

Abstract

As a part of serial studies on differential thermal analysis of edible oils, similar analyses were carried out on hardened fish oil and rape-seed oil, having a longer chain than the usual edible oils, and on fish oil blended in various ratios with coconut oil having an extremly different molecular chain.1) The differential thermal analysis (DTA) curve of hardened fish oil (I.V. 52.7), allowed to stand at 0°C and 20°C, showed one large and broad endothermic peak at 34°C and an indistinct and gentle peak was present in the low temperature side. When left at 30°C, the curve showed a great difference, and a peak of broad melting range appeared on both sides.2) The DTA curve of hardened rape-seed oil (I.V. 69.9), allowed to stand at 0°C, showed a large, broad peak at 2127°C. When left at 20°C, a small but gentle peak appeared in the low temperature side as well. When left at 30°C, two endothermic peaks appeared and the peak in the low temperature side increased in size with lapse of time.3) Addition of 10% of coconut oil to hardened fish oil had no effect on its DTA curve but addition of 20% resulted in a broad peak with a broad melting range in the low temperature side. When the amount of coconut oil added was increased to 40 and 60%, the large peak in the low temperature side, corresponding to that of coconut oil, increased in size, and this peak became larger and clearer with higher temperature and longer time of standing.4) When coconut oil was added to hardened fish oil in 80 or 90%, DTA curve of the samples shovcted a characteristic curve of the coconut oil and the melting range became narrower.