Acta Agriculturae Zhejiangensis ›› 2022, Vol. 34 ›› Issue (8): 1752-1761.DOI: 10.3969/j.issn.1004-1524.2022.08.19

• Food Science • Previous Articles     Next Articles

Optimization of DNA extraction method and DNA barcoding identification of walnut milk

HUANG Lingzhi1(), JIANG Guangze2, DING Yanfei1, ZHU Cheng1,*()   

  1. 1. Key Laboratory of Specialty Agri-Product Quality and Hazard Controlling Technology of Zhejiang Province, College of Life Sciences, China Jiliang University, Hangzhou 310018, China
    2. Hangzhou Dean Medical Testing Center Co., Ltd., Hangzhou 310030, China
  • Received:2021-11-03 Online:2022-08-25 Published:2022-08-26
  • Contact: ZHU Cheng

Abstract:

With the rapid development of milk beverage industry, adulteration of milk beverage was common, thus it is particularly important to accurately identify the true ingredients of walnut milk. Walnut milk is a deep-processed food with severe DNA damage. DNA extraction is the first step in DNA barcode identification of walnut milk. The purpose of this experiment was to optimize the DNA extraction method of walnut milk, and to establish an adulteration and fraud identification method based on psbA-trnH gene DNA barcoding. Taking 10 different brands of walnut milk as samples, three methods (static extraction, isopropanol precipitation and vacuum lyophilization) were used for pretreatment. Walnut milk DNA was extracted using two CTAB lysate precipitation methods and three kit methods (Kangwei Nuclean Plant Genomic DNA Kit, AxYGen AxyPrep Multisource Genomic DNA Miniprep Kit, and TianGen Deep Processing Food DNA Extraction Kit). Furthermore, CTAB and AxYGen kit was combined for DNA extraction. Using the extracted commercial walnut milk DNA as a template, the self-designed specific gene psbA-trnH-wal was used to identify whether the sample contained walnut components, and the fraud situation was determined. The common plant candidate gene psbA-trnH was selected to identify whether the sample contained other components, to determine adulteration. Vacuum freezing method was superior to the other two pretreatment methods. Walnut milk extracted DNA using CTAB and AxYGen kit combination method was in good purity, high yield and strong amplification ability, thus it was the best method for walnut milk DNA extraction. Amplification and comparison results showed that one walnut milk sample contained peanuts, which belonged to adulterated products. The vacuum freezing method and the combination of CTAB and AxYGen kit combination method were the optimized methods for DNA extraction from walnut milk. The combination of psbA-trnH-wal gene and psbA-trnH gene could quickly and accurately identify walnut milk and its adulterated fakes.

Key words: walnut milk, DNA extraction, DNA barcode, psbA-trnH, label verification

CLC Number: