The nutritional potential of grape by-products from the area of Slovakia and Austria

Abstract

Current experiments with farm animals showed that it is possible to use grape by-products as a source of nutrients in animal nutrition. In the present experiment, we hypothesize that one reason for the variation among feeding trials, besides production steps affecting byproduct quality in winery, the variation among cultivars may have substantial contribution. The main aim of this study was to analyse grape pomace and stems from the area of Slovak Republic and Austria to evaluate their nutritional value for animals. In total, 54 samples of 3 grape varieties from 6 different locations were analysed. In each variety basic nutrients, antioxidant activity, total phenols, condensed tannins and proteins participation was determined according to standard analytical methods. The results show that the grape pomace had the highest ratio of crude proteins, crude fat and crude fibre with the solid concentrations of sugars, except of variety from red grape. Then, the grape stem is characterised with balanced content of crude protein, crude fibre and nitrogen free extracts with residual sugars and the highest antioxidant activity. By-products from the winery production have average nutritional value because of higher content of lignin that could be limiting factor for the digestibility. Neverthelles, there are interactions between the fibre fractions, condensed tannins, total polyphenols and antioxidant activity. Analysed data shows, that grape by-products have a potential in animal nutrition as a source of bioactive compounds, however there exists differences between the locations and varieties.

The use of emergent technologies to extract added value compounds from grape by-products

“…This difference depends on both grape cultivar and type of winemaking by-products. While for grape pomace, the red cultivars present superior values of proteins than the white grapes pomace, for stems higher significant values of proteins than the red grapes have been found (Hanušovský et al, 2020).…”

“…Proteins are Table 1 Chemical Composition of grape by-products concerning Fiber, Proteins, Minerals, Vitamins, and Polyphenols (%). Sousa et al, 2014;Beres et al, 2016;Hanušovský et al, 2020 Vitamins Vitamin E 20 Vitamins are needed for normal cell function, growth, and development. Karnopp et al, 2017;Sousa et al, 2014 Vitamin C 2.6 0.5-0.01 Minerals Total minerals 1.0-6.0 0.9-6.8 0.9-5.7 1.3 3.8 0.9-7. comprised of ca.…”

“…The amounts of proteins reported in grape by-products ranged from 6.2 to 13.8% of DM (Beres et al, 2016;Hanušovský et al, 2020;Karnopp et al, 2017;Karovičová et al, 2015;Ribeiro, de Lima, Alves, Gonçalves, & Souza, 2018;Tseng & Zhao, 2013). This difference depends on both grape cultivar and type of winemaking by-products.…”

“…As verified before, there are differences in the mineral content of grape by-products associated with the edaphoclimatic conditions, viticultural practices and winemaking process. Besides, the duration and type of maceration process (in the winemaking process) have a strong influence on the minerals extraction and reabsorption, conditioning the minerals content of grape by-products (García-Lomillo et al, 2014;Hanušovský et al, 2020).…”

Anthocyanin Recovery from Grape by-Products by Combining Ohmic Heating with Food-Grade Solvents: Phenolic Composition, Antioxidant, and Antimicrobial Properties

“…However, previous research has shown that the anthocyanin content of a given cultivar is not necessarily positively linked with anthocyanin concentration in the resulting wine. The lack of association was due to the partial preservation by cell-wall polymers of these anthocyanins in the skin cells [2,11,12].…”