Grapes cultivar assignments using the identified elements-markers of grape berry and its different constituent parts

Abstract

The objects of our research were the samples of Cabernet and Riesling grape varieties produced in the Krasnodar Territory, Russia. The samples of grapes have been provided by their direct producers. The features of the multi-element analysis of grape berries by the method of AES-ICP were examined, their distribution in berry peel, bones and pulp as well as the revealed elements-markers of varietal belonging of grapes were studied. The conditions for preparing the samples of grapes and its main parts for the analysis by the microwave acid mineralization were optimized, ensuring a minimum level of losses of the elements to be determined. The elemental composition of Riesling and Cabernet grape varieties grown in the Kuban region was studied under the optimized conditions by the AES-ICP method. It was shown that the concentrations of some elements, both in different parts of the grapes and in different grape grades, differ significantly. The step-wise discriminant analysis, implemented in the STATISTICA program, was used to separate the samples according to the elemental “image” of the berry parts and the grape variety. The classification analysis with training allowed graphically presenting the intergroup differences between the objects. For the implementation of the discrimination process a step-by-step with exception method was selected that allowed excluding 15 elements successively, and defining the remaining 6 elements (Ba, Cr, Mg, Rb, Sr, Ti) as the markers for distinguishing the different fragments of Cabernet and Riesling grapes. A scattering diagram of canonical values was constructed that showed the localization of clusters of berries samples corresponding to the 6 groups in certain parts of the plane at a considerable distance from each other. The classification functions were developed that helped identifying the grape varieties by the content of the marker elements in one of the three parts of the grape berries - pulp, peel or bone.