PROCESS CHANGES IN POLYPHENOLIC SUBSTANCES AFTER PROCESSING ARONIA INTO VARIOUS FOOD PRODUCTS

Abstract

The chokeberry is a plant with interesting biological potential and versatile uses. The most nutritionally valuable are the fruits, which are characterised by their high content of procyanidins, anthocyanins, flavonoids and phenolic acids. The aim of this work was to evaluate selected parameters of the composition of the fruits of the chokeberry varieties Nero and Galicjanka and to compare chokeberry products such as pasteurized chokeberry juice and puree, chokeberry jam, jelly and reduced sucrose jam, dried fruit and dried puree and baked chokeberry tea in terms of the stability of the total content of polyphenols and anthocyanins. Infrared spectroscopy was used to determine soluble solids, sugars, organic acids and pH. Determination of total polyphenols was carried out spectrophotometrically using Folin-Ciocalteu reagent. Determination of anthocyanin dye content was also performed spectrophotometrically by the pH differential method.  Results were evaluated using one-way analysis of variance (ANOVA) followed by post hoc analysis of statistically significant differences between chokeberry products using the LSD multiple range test (Statistica 12, Statsoft). Fresh chokeberry fruits were high in soluble solids (22.8%), which is mainly composed of carbohydrates (19.71 g.100 g^-1). The average glucose, fructose and total organic acid contents of the fruit were 5.85 g.100 g^-1 FW, 4.89 g.100 g^-1 FW and 1.02 g.100 g^-1 FW, respectively. The fruits were characterised by a high content of total polyphenols (6.89 g GAE.100 g^-1 DM), of which almost 45% were anthocyanin dyes with an average content of 3.05 g CGE.100 g^-1 DM. The content of total polyphenols and anthocyanins decreased in the prepared products due to processing and heat treatment. The content of total polyphenols in the prepared products ranged from 3.32 to 5.53 g GAE.100 g^-1 DM and the content of total anthocyanins from 1.14 to 2.40 g CGE.100 g^-1 DM. Statistically significant (p<0.05) the highest content of total polyphenols was retained in the pasteurized chokeberry juice and the lowest content in the roasted chokeberry tea. The highest content of total anthocyanins remained statistically significant (p<0.05) in pasteurized chokeberry juice and chokeberry puree and statistically significant (p<0.05) lowest in roasted chokeberry tea. Despite the decrease in the polyphenolic content of products prepared from chokeberry, these products are characterised by a high content of bioactive substances and chokeberry is a raw material suitable for the production of value-added foods.