Deterioration of partially hydrogenated soybean oil used in deep fat frying of a meat food

Abstract

The deterioration of partially hydrogenated soybean oil used in deep fat frying of a meat food called milanesa for evaluating its behavior according to the Argentinian Food Codex (CAA) at laboratory scale was studied. Two differebnt lots of the oil, in batch process, with fresh oil turnover were heated at 180ºC ± 2 ºC for 42 and 56 h, respectively. Deterioration was followed through the evolution of free fatty acid percentage, polar compounds, distribution of these deterioration species and fatty acid composition. In the first lot, at 42 h of heating, polar compounds increased from 4.6 % at t' 0 to 16 % (120 milanesas fried). In the second lot, at 56 h of heating, polar compounds increased from 2.5 to 27.6 % (160 milanesas fried). The main deterioration was thermal, considering the presence of triglycerides polymers and dimers in polar compounds, followed by hydrolytic deterioration. The free fatty acid percentage was higher than the maximum level of 1.25 % established in the CAA at an early stage of the frying process. According to the results of this study, it is recommended to include polar compound percentage as a measure of frying control processing and to check the free fatty acid value, which is considered too low.