| In order to obtain the optimal conditions of extracting duck oil by wet boiling, taking the extraction rate of duck oil as an index, L9(33) orthogonal experiment design was adopted to optimize the conditions by taking the ratio of raw material to water, boiling time and heating furnace temperature as factors. The acid value, peroxide value, heavy metal content and fatty acid composition of duck oil extracted under the optimal conditions were determined.The results showed that the optimal extraction conditions of duck oil by wet boiling method were obtained as follows: ratio of raw material to water 1∶ 3, boiling time 0.5 h, heating furnace temperature 140 ℃. Under the optimal conditions, the extraction rate of duck oil was 82.4%. The ratio of raw material to water, boiling time and heating furnace temperature had extremely significant effects on the extraction rate of duck oil (P＜0.01). Under the optimal conditions, the quality of duck oil was better, and the acid value was 2.01 mgKOH/g, lower than that of GB 10146—2015(less than or equal to 2.50 mgKOH/g). The peroxide value was 0.24 g/100 g, slightly higher than that of GB 10146—2015(less than or equal to 0.20 g/100 g). The contents of total arsenic, lead and nickel were all less than 0.1 mg/kg, which met the national standard of food safety (GB 2762—2017).Duck oil contained 23.87% of saturated fatty acid, mainly palmitic acid(18.58%) and stearic acid(3.97%), and 60.30% of unsaturated fatty acid, mainly oleic acid(37.59%), linoleic acid(18.35%) and palmitoleic acid(3.07%), and 19.60% of polyunsaturated fatty acid, mainly linoleic acid.The ratio of polyunsaturated fatty acid to saturated fatty acid was about 0.82∶ 1. |
