Method for rapidly determining delta <13>C value of malic acid in fruit juice

Abstract

The invention relates to a method for rapidly determining the delta <13>C value of malic acid in fruit juice. The method comprises the following steps: step a, taking a fruit juice sample, diluting the fruit juice sample by 150-250 times, and carrying out filtering to obtain a filtrate; and step b, determining the delta <13>C value of the malic acid by using a liquid chromatography-stable isotoperatio mass spectrum. The chromatographic column used by the liquid chromatography-stable isotope ratio mass spectrum is a hydrophilic reversed-phase C18 chromatographic column. According to the invention, a complex sample pretreatment process is not needed; the malic acid can be automatically separated and purified by simply diluting and filtering a sample and depending on the separation efficiency of a chromatographic column, so that the purpose of quickly and directly measuring the malic acid delta <13>C is achieved; and a novel method for directly measuring the malic acid delta <13>C without pretreatment is provided for adulteration detection research of fruit juice products.

Description

technical field [0001] The invention relates to a method for rapidly determining malic acid δ in apple juice 13 The method for C value, specifically, the present invention relates to measuring fruit juice, particularly apple juice, malic acid stable carbon isotope ratio (recorded as δ 13 The method of C) belongs to the technical field of stable isotope analysis. Background technique [0002] Apple juice contains sugar, organic acids, vitamins, amino acids, flavonoids and other substances, and has high nutritional value. International Food Codex Alimentarius Commission (CAC) stipulates (CODEX STAN 247-2005): If sugar or organic acid is added to pure fruit juice, it must be indicated on the label; It also stipulates that any substance used in food manufacturing or processing and present in the product must be listed in the ingredient list of the product, and the content of the added substance is limited. In 2012, the Council of the European Union passed a new fruit juice di...

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Problems solved by technology

The adulteration of apple juice is a serious economic and social problem. It will not only cause the loss of economic interests of consumers, but also affect the healthy development of regular fruit juice enterprises, cause disorder in the juice industry, and affect the import and export of fruit juice in my country.

However, due to the limitations of liquid chromatography-stable isotope ratio mass spectrometry (the organic phase cannot be used as the mobile phase) and the chromatographic separation performance of organic acids in fruit juice, there is no direct and rapid analysis of the δ13C value of malic acid in apple juice. report: Guyon et al. found that liquid chromatography-stable isotope ratio mass spectrometry cannot separate various organic acids in fruit juice, so it can only measure the δ13C values ​​of all organic acids in fruit juice. Zhu Weixia (see non-patent literature 11) also It was found that the chromatographic peaks of fructose and malic acid overlapped during the analysis, and accurate analysis could not be achieved

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