3.5 Determination of 3-MCPD esters in oil samples
Soybean oil, rapeseed oil, palm oil and peanut oil were detected by gas GC-MS, which was established by enzyme-hydrolyzed sample pretreatment method. According to the experimental method of 2.5, each sample was measured six times in parallel to take the average value, the content of 3-MCPD ester was calculated according to the peak area and linear regression equation obtained by GC-MC detection. The contents of 3-MCPD ester in palm oil, peanut oil, rapeseed and soybean oil were as follows: 5.52, 3.02, 2.87 and 2.73 mg/kg.
Conclusion
In this study, the optimal conditions for enzymatic hydrolysis of 3-MCPD esters were obtained by single factor test as follows: lipase from Candida sp. was selected, enzyme concentration was 150 U/mL, the enzymatic hydrolysis temperature was 25℃, the enzymatic hydrolysis time was 30 min, and the pH was 5. Secondly, the standard curve of the 3-MCPD standard solution was drawn, and then the edible oil sample was processed before enzymatic hydrolysis according to the optimal enzymatic hydrolysis conditions, derived with PBA, and finally detected by GC-MC. The content of 3-MCPD ester in four kinds of vegetable oil was obtained by combining the standard curve, and the content of 3-MCPD ester in food oil could be detected simply and quickly.