Methodological approaches to gene identification of tea raw materials and raw material composition of tea-based soft drinks

Abstract

Tea or tea shrub is a plant of the Camellia sinensis species, the leaves of which, previously prepared in a special way, are the traditional raw material for the production of tea products. Varietal gene identification of tea allows us to increase the level of assessment of the authenticity of tea raw materials and tea products. It is predominantly based on DNA technologies for the detection and interpretation of SNP markers (Single Nucleotide Polymorphism), represented by a wide arsenal of both expensive high-tech methods and publicly available laboratory approaches. Species gene identification of the raw material composition of tea-based soft drinks is an equally important area of research due to the risk of falsification of this type of product. The purpose of this study was to find methodological approaches to the varietal gene identification of tea raw materials and to the species gene identification of the raw material composition of tea-based soft drinks. As a result of a bioinformatics study to identify polymorphic restriction sites in the nucleotide sequences of Camellia sinensis genome loci, diagnostically significant restriction enzymes were selected that were capable of detecting SNPs and identifying tea genotypes using the analyzed markers. At the same time, 16 loci had potential for practical application, of which 11 belonged to the group of the most informative SNP markers. A post-analytical assessment of tea varieties was carried out with them regarding their genotypic affiliation and identifiability as part of solving the first task of the study. To achieve the second task, a molecular genetic approach to the species identification of the raw composition of soft drinks based on green tea was tested. The study included the analysis of experimental drinks (with natural flavoring “Lemon” and synthetic flavoring “Peach 716”), as well as commercial concentrates “TIAKVA” (based on extracts from the coarse stems of green or black tea). The methods used in the work were PCR (Polymerase Chain Reaction), RFLP (Restriction Fragment Length Polymorphism) and direct sequencing of the amplified chloroplast DNA locus. The combination of two methods (PCR and sequencing) showed its effectiveness in establishing the belonging of the analyzed nucleic acid samples to the Camellia sinensis species, the raw material base of the studied drinks and concentrates. However, to unlock the authentication potential of PCR with primers #1 and #2 combined with RFLP analysis, it will be necessary to select diagnostically significant restriction enzymes suitable for generating species-specific combinations of PCR-RFLP profiles of marker sequence.