Effect of Pre-fermentation Maceration on the Content of Antioxidant Compounds in Grapevine Juice

Mojmir Baron,Jiri Sochor,Lenka Tomaskova,Bozena Prusova,Michal Kumsta

doi:10.15835/nbha45110531

Abstract

Lower antioxidant capacity of white wines is caused by a lower content of phenolic compounds. In red wine, a higher content of phenolic compounds is the result of maceration. This study deals with effects of pre-fermentation maceration on contents of some selected compounds (above all antioxidants) in juices made of grapes of white varieties 'Welschriesling', 'Green Veltliner' and 'Neuburger'. The grapevine mush was macerated for 0; 2; 4; 8; 12; 24 and 48 hours. The spectrophotometry methods was used to estimate juice antioxidant activity and content of flavanols, anthocyans, catechins, hydroxycinnamic acids and flavonols. Contents of total titratable acids and pH were estimated as well. Results of this study show increasing tendency of all parameters with length of maceration. The highest content of antioxidants were found out in the variety 'Welschriesling'. Important are increasing values of hydroxycinnamic acids. However, the main role of the phenolics acids is to contribute to the anti-oxidant capacity, the tartaric esters of hydroxycinnamic acids (particularly caftaric acid) are centrally involved in oxidation and browning reactions in white wine. Their levels increased during the whole period of maceration. In 'Welschriesling', their content increased by 74 mg·L-1. Decreasing tendency show results of titratable acids. Their contents decreased within the first 12 hours of maceration and thereafter they do not change. Longer must maceration could contribute to a decrease in contents of total titratable acids and, thus, to a better harmony of produced wine.

Highlights

In the course of alcoholic fermentation, the process of maceration enables to extract phenolic compounds contained in solid parts of grapes
The most frequently discussed problem is the increase in contents of phenolic substances, aromatic compounds and organic acids during maceration of white wines
The total antioxidant activity was significantly correlated with levels of total phenolic substances and flavonoids

Summary

Introduction

In the course of alcoholic fermentation, the process of maceration enables to extract phenolic compounds contained in solid parts of grapes. The maceration step, mostly used in technology of red wines, results in the extraction of phenolic substances and production of grape juices and wines rich in these compounds and showing strong antioxidant properties. This maceration step is the most important difference between technology of red and white wine (Paganga et al, 1999). The most frequently discussed problem is the increase in contents of phenolic substances, aromatic compounds and organic acids during maceration of white wines. Phenolic substances occur above all as hydroxycinnamic acids that play a decisive antioxidant role prior to the onset of fermentation because they react with polyphenol oxidase and Received: 16 Aug 2016.

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