Abstract:

Abstract: In order to find the new parameters of edible quality for frying oil and to achieve rapid detection on the spot, the edible soybean oil from different areas were researched. Carbonyl value promulgated by the nation was taken as reference standard. The changes of pH value and conductivity were analyzed as carbonyl value exceeded the national standard during batch deep-frying. The results showed that the carbonyl value increased obviously, pH value decreased gradually, conductivity increased and then decreased slightly with the increase of frying time. After batch deep-frying 12h, soybean oil couldn't be used as food when carbonyl value had exceeded the national standard, pH value was 4.16, H+ activity was 100 times and conductivity was 5 times to the fresh soybean oil. There were obvious correlativity between carbonyl value, H+ activity and the frying time. The relationship between conductivity and the frying time, carbonyl value was significant generally. It suggested pH 4.20 was considered as a new expression parameter that could be used to identify the edible quality of fried soybean oil.