Influence Of Oak Chips And Plant Extracts On Phenolics Composition And Colour Parameters Of Blueberry Wines During Bottle Storage

With the extension of storage time in bottle, the colour of blueberry wines gradually turns to yellow, influencing the sensory quality of products. Anthocyanins, known as the main present-colour component, plays a decisive role in the colour of wine. However, the structural characteristics of anthocyanins determine its poor stability. Stabilizing the structure of anthocyanins by adding copigmentation substance, which can alleviate the speed of colour shift to brick red, is a method worth in-depth exploration. This subject was engaged in adding oak chips and plant extracts with various doses as well as toast levels to blueberry wines. Then the effects on phenolics compounds and antioxidant activity of blueberry wines were studied by spectrophotometry; the change of monomeric anthocyanins, phenolic acids and flavonols, flavanols were analyzed by HPLC-MS; the copigmentation contribution on wine colour was compared based on detecting CIELab colour parameters; the relationship between diverse phenolic compounds and colour were parsed by correlation analysis and principal component analysis. The results are as follows:(1) Adding oak chips, gallnut extracts and pomegranate rind extracts improved the phenolic compound level in blueberry wine significantly, which was positive related to the addition doses. The differences of phenolics composition between different treatment samples decreased during the later storage stage.(2) Adding oak chips, gallnut extracts and pomegranate rind extracts could stabilize the structure of monomeric anthocyanins, improve the percentage of copigment anthocyanins.(3) The doses of oak chips had remarkable effects of stabilising red hue of wine samples, while toasting degree imposed less effect; Different plant extracts had various protection effect on red hue. Gallic acid as main component of gallnut extract were determined to be the best, followed by tannic acid, which showed positive relevance to addition doses. Although pomegranate rind extracts could inhibit the degradation of monomeric anthocyanins in wines, these yellow-brown coloured extracts, to a large extent, counteracted its positive effect on wines colour; As storage time went by, the colour of blueberry wines was shifted from reddish violet to brick red.(4) Compared to oak chips, gallic acid and tannic acid shown a better effect on colour protection during the later storage;(5) Correlation analysis and principal component analysis indicated that various anthocyanin composition presented relevance to colour parameters of blueberry wines, and some correlative differences were found. Non-polymeric contributed mainly to red hue and color saturation of wine, whereas polymeric anthocyanins enhanced the yellow hue and lightness.