Method for quickly measuring methanal content in dried beancurd sticks

Abstract

The invention relates to a method for quickly measuring methanal content in dried beancurd sticks, which is characterized by adopting a combined using method of an efficient liquid phase chromatogram method and a viable wavelength detector (VWD) to qualitatively and quantitatively measure methanal content in dried beancurd stick products. The method comprises the steps of using Nash reagent to perform precolumn derivation and chromatographic analysis on derivation products, enabling the detection wavelength of the VWD to be 412nm, and performing gradient elution with a binary system of acetonitrile and water as flow phase. The flow speed is 0.8mL / min to 1mL / min, the judgment standard of the methanal content is that a linear range of the methanal content is 0.00 to 0.80mg / L, the linear equation is that Y is equal to 27.024X, the Y is the peak area of derivation reaction products, and the X is the methanal content. The method has the advantages that compared with GB / T21126-2007, the derivation reaction time is shortened from 40 minutes to 15minutes, products are not required to be extracted by organic solvent, loss of derivation products is reduced, labor intensity is reduced, and chemicals are saved. Methodology experimental results of the method meet analysis requirements of samples, thereby achieving the purpose of quick analysis.

Description

technical field [0001] The invention relates to the field of food detection methods. In particular, it relates to a method for rapidly measuring formaldehyde content in bean curd sticks. Background technique [0002] Yuba is obtained by boiling soybean milk, removing the fat and soybean protein conjunctiva and drying it. As the cooking time increases, the conjunctiva becomes less and less, and the remaining carbohydrate-based substances will undergo a "browning reaction" and even turn black. Adding the highly reductive white block can play a "bleaching" effect, which not only changes the color, but also increases the yield. Hanging white block is an industrial raw material, which is used as a reduction catalyst in the printing and dyeing industry and synthetic rubber. It decomposes under acidic conditions to produce formaldehyde. At home and abroad, it is forbidden to use scallops or formaldehyde for food processing. [0003] In April 2011, an announcement was made on th...

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Problems solved by technology

Among them, the more commonly used high-performance liquid chromatography and spectrophotometry have deficiencies in practical application. The first is that the GB / T 21126-2007 method uses 2,4-dinitrophenylhydrazine as a derivatization reagent, and the derivation reaction time is long, and the derivation product Need organic solvent n-hexane extraction, there are many experimental steps, long time, deficiencies in loaded down with trivial details operation; The 2nd, the mensuration of formaldehyde sodium bisulfoxylate in food of document No. For bean curd sticks, the distillation process produces a large number of bubbles, which makes the effluent liquid unclear. Sometimes, due to the presence of pigment in the sample, the effluent liquid is colored, which affects the determination of absorbance. method

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