Chemometric guidelines for selection of cultivation conditions influencing the antioxidant potential of beetroot extracts

The estimation of influences of different cultivation conditions on chemical composition of crops can be quite complex task. Usually, the classical statistic approach (comparison of statistical characteristics of different populations) is applied. However, this study presents the analysis of the influence of different cultivation conditions (cultivation with or without foil cover, different preceding crops and fertilization) on the contents of dry matter, betalains and phenolic compounds in 64 beetroot (Beta vulgaris L. ssp. vulgaris) samples and their antioxidant potential (IC50) by using powerful chemometric tools, such as Wald-Wolfowitz run test, cluster analysis and sum of ranking differences, in order to obtain groupings of the samples which share similar properties or to test if the samples come from the same population. Besides the aforementioned classification or pattern recognition analysis, the regression methods (linear, multiple linear and artificial neural network regressions) were carried out in order to establish reliable linear and non-linear relationships between IC50 and contents of betalains, phenolic compounds and dry matter. The results reveal certain influence of foil cover, used during the cultivation, on beetroot antioxidant potential and content of the determined betalains and phenolic compounds, as well as the strong non-linear relationship between the analyzed variables. Certain influence of preceding crops on phenolic compounds content is detected by Wald-Wolfowitz run test. (C) 2015 Elsevier B.V. All rights reserved.