Control of the selectivity of the separation of grape anthocyanidin 3-glucosides and 3,5-diglucosides: determination of anthocyanins in grape fruit grown in the belgorod region

For the first time, a new version of the separation of 3-glucosides and 3,5-diglucosides of the five main anthocyanidins for grape fruits -delphinidin, cyanidin, petunidin, peonidin and mal-vidin under reverse-phase HPLC conditions was proposed. It has been shown that the replacement of the traditionally used acetonitrile with environmentally more acceptable ethanol upon acidifica-tion with ortho-phosphoric rather than formic acid makes it possible to significantly change the selectivity of the separation of two types of glucosides at their joint presence. The proposed separa-tion option allows differentiating between Vitis vinifera grapes, in the fruit peel of which only 3-glucosides of the above anthocyanidins are synthesized, and grapes of other species or hybrid grape varieties. For a complete review of the anthocyanin composition, it is necessary to use a gradient mode, since the acylation of anthocyanins with acetic and p-coumaric acids significantly changes the lipophilicity of anthocyanins. The type of anthocyanins was analyzed according to the previously proposed system, which takes into account the activity of three types of enzymes: 1) 5-O-glucosyltransferase that leads to 3,5-diglucosides synthesis; 2) 3',5'-hydroxylase responsible for ring B hydroxylation; 3) anthocyanin O-methyltransferase for converting cyanidin into peonidin derivatives as well as delphinidine into petunidin and malvidin glycosides. The method was used to determine anthocyanins in 43 grape varieties grown in Belgorod on farms and private farms. Among the studied grapes, varieties were found with grape fruits with the accumulation of only 3-glucosides, as well as 3-glucosides and 3,5-diglucosides simultaneously, with delphinidin and cyanidin types of anthocyanins, and with different degrees of methylation. The calculated parameters for all grape varieties are presented in two tables and a brief discussion of some varieties is given.