engleski

Applying different maceration treatments to increase the antioxidant capacity and vitamin content of Malvazija istarska wines

Besides its hedonic nature, wine is a natural beverage with certain health-related properties, which is why the consumer’s interest towards wines with a higher concentration of bioactive compounds has increased over recent years. Extracted from grapes, antioxidants and vitamins are naturally present in wines but their concentrations differ according to the applied winemaking technique. The maceration process is less frequently carried out for the production of white wines in relation to red wines for several reasons, but its application may be suggested to increase wine antioxidant capacity and nutritional value. The aim of this study was to investigate the effect of applying different maceration processes on antioxidant capacity and vitamin content of wines produced from an autochthonous Croatian white grape variety, Malvazija istarska (Vitis vinifera L.). Vinification took place in vintage 2019 at the Institute of Agriculture and Tourism (Poreč, Croatia) where six vinification treatments were carried out: non-maceration control treatment (C), pre-fermentative two days cryomaceration treatment at 8 °C (CRYO), seven days maceration treatment at 16 °C (M7), and prolonged post-fermentative maceration treatments at 16 °C for 14 days (M14), 21 day (M21), and 42 days (M42). The antioxidant capacity of the wines was determined by the ferric reducing/antioxidant power, FRAP (mM Fe2+) assay and the oxygen radical absorbance capacity, ORAC (mM Trolox) assay. Chromatographic analyses were performed on a liquid chromatography system with a DAD and single quadrupole mass detector equipped with electrospray ionization interface. Identification of five vitamins (B1, B2, B3, B6 and C) was carried out by comparison to the retention times of authentic standards and their spectral properties. Statistical data analysis was performed using one-way analysis of variance (ANOVA) and Fischer’s least significant difference (LSD). According to both FRAP and ORAC assay, antioxidant capacity increased proportionally with the maceration duration, with control treatment wine having the lowest, opposed to M42 treatment wine having the highest values. Such results indicate that the antioxidant properties are mostly related to phenolic compounds which are mainly present in prolonged maceration treatments such as M42. Contrary results were noted for vitamin C content that showed a decreasing trend as maceration progressed. Vitamin C was not detected in M42 treatment wine while the highest concentration was reported in control treatment wine. When observing total B-group vitamins, a significant difference was noted between treatments. Prolonged post-fermentative maceration treatment M42 resulted with the highest concentration of total B-group vitamins in relation to other treatments. The increase in total B-group vitamin was proportional with maceration time, while CRYO and M7 treatments did not significantly differ from control treatment wine. Regarding the concentrations of each individual vitamin, vitamin B3 reached the highest values, and its concentration was significantly the highest in M42 treatment wine. A similar trend was noted in the concentration of vitamin B6. Obtained results showed that prolonged maceration significantly affects both the antioxidant capacity of the wines and their vitamin content, particularly B-group vitamins. Such information may serve producers for choosing the adequate technological practice for improving wine quality and its nutritional value. The study was funded by the Croatian Scientific Foundation under the projects VINUM SANUM (IP 2018-5049) and DOK-2020-01-1901.

maceration ; antioxidant capacity ; vitamins

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