Quantitative detection method for fatty acid in food

Abstract

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.

Description

technical field [0001] The invention belongs to the technical field of detection, and in particular relates to a method for quantitative detection of fatty acids in food. Background technique [0002] Fatty acids exist in walnut kernels in the form of fatty acid triglycerides. In enterprises, the total fat content in walnut kernels can be determined according to the second method of acid hydrolysis in GB / T5009.6-2003 "Determination of Fat in Food". Enterprises generally use the saponification of fat and methyl esterification of fatty acids in GB / T22223-2008 for sample preparation. Specifically, add 8mL of 2% sodium hydroxide solution to a 250mL beaker containing fat extract, and connect the reflux condenser Reflux on a water bath at 80°C until the oil droplets disappear; add 7 mL of 15% boron trifluoride methanol solution from the upper end of the reflux condenser, and continue to reflux in a water bath at 80°C for 2 min; rinse the reflux condenser with deionized water. Sto...

AI Technical Summary

Problems solved by technology

It is often necessary to add internal standards such as triglyceride undecylcarbonate and pyrogallic acid, which makes the operation complicated

Due to the need to add multiple reagents in batches, it is easy to produce errors and affect the accuracy of measurement results

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