Quantitative detection method for fatty acid in food

The invention relates to a quantitative detection method for fat in food, and belongs to the measuring technical field. The method particularly comprises fatty acid methyl esterification operation and adopts the following method: weighing 0.5 g of an evenly-mixed walnut kernel sample, placing in a 50 mL centrifugal tube with a plug, adding 0.1 mL of 1:1 hydrochloric acid and 10 mL of n-hexane, covering with a lid of the centrifugal tube, carrying out sufficient oscillation for 3 min, carefully opening the lid, releasing gas, centrifuging for 10 min at a speed of 7000 r/min, sucking the supernatant with a rubber-head dropper to a test tube with a plug, and thus obtaining a n-hexane-fat liquid; and taking more than or equal to 2.0 mL of the prepared n-hexane-fat liquid in a 10 mL graduated test tube with a plug, adding 0.8 mL of a 0.5% KOH-methanol solution, carrying out sufficient oscillation for 2 min in a vortex mixer, allowing to stand for 2 min, and sucking the supernatant, namely a fatty acid methyl ester sample liquid. The method is simple to operate, allows the reaction to be carried out only at room temperature, has the advantages of good data repeatability and reproducibility, high precision degree and simple steps, reduces errors caused by incomplete extraction or methyl esterification, internal standard substance preparation and other many aspects, and has fewer error introducing factors.