Evaluation of anthocyanin changes in blueberries and in blueberry jam after the processing and storage

Abstract

Blueberry (Vaccinium corymbosum L.) is worldwide famous as the healthy and desirable fruit. The most valuable nutritional components of fruits are polyphenols, which include anthocyanins. The aim of the study was to assess the content of anthocyanin dyes in selected varieties of blueberry fruit. We evaluated the changes in the content of colorants that occur after treatment for fruit jam and its subsequent storage at 21°C under the light. Varieties Ramcocas, Record, Iranka, Nelson, Pemberton, Jersey and Coville were observed. Content of anthocyanins was determined spectrophotometrically. In fresh fruits anthocyanin content ranged from 9.878 g kg-1 of dry matter (Jersey variety) to 18.555 g kg-1 of dry matter (Nelson variety). After treatment there was found a decrease in the anthocyanins content, in the product's content were determined in the amount 1.645 g kg-1 of dry matter (Jersey variety) to 3.476 g kg-1 of dry matter (variety Ramcocas). The decrease was due to decomposition of anthocyans at high temperatures in processed products and also by the replacement of dry matter by sucrose in the product. Mean color decrease in blueberry jam was 84.5%. After storage of the product, there were found further degradations of colorants, evaluated at 34.9%. The content of anthocyanin in jam was found to be 1.089 g kg-1 of dry matter (Jersey variety) to 2.199 g kg-1 of dry matter (Ramcocas variety). © 2013 Potravinarstvo.