Analysis of off flavours in grapes infected with the fungal bunch rot pathogens, Aspergillus, Botrytis and Pencillium

Oligosaccharides have only recently been characterized in wine, and the information on composition and content is still limited. In wine, these molecules are mainly natural byproducts of the degradation of grape berry cell wall polysaccharides. Wine oligosaccharides present several physicochemical properties, being one relevant factor linked to the astringency perception of wines (1,2). A terroir can be defined as a grouping of homogeneous environmental units based on the typicality of the products obtained. This notion is particularly associated with wine, being the climate and the soil two of the major elements of terroir concept.

Grape phenolic compounds are very important constituents of red wine because, in addition to their antioxidant properties, they contribute to color, astringency and bitterness, oxidation reactions, interactions with proteins and ageing behavior of wines. The aim of our study was to assess the structural characteristics of grape and wine proanthocyanidins of Agiorgitiko variety and to evaluate the influence of the vintage year. Twelve vineyard locations were designated in the Nemea wine region. For three consecutive years (2012-2014), the grapes were harvested at technological maturity and the method of phloroglucinolysis was employed to determine the mean degree of polymerization (mDP) and subunit composition of the samples.

Tannin, anthocyanins and their reaction products play a major role in the quality of red wines. They contribute to their sensory characteristics, particularly colour and astringency. Grape tannins and anthocyanins are extracted during red wine fermentation. However, their concentration and composition change over time, due to their strong chemical reactivity1. It is also well known that yeasts influence the wine phenolic content, either through the release of metabolites involved in the formation of derived pigments1, or through polyphenol adsorption2,3.

Beihong and Beimei were bred as winemaking cultivars released by Institute of Botany, the Chinese Academy of Sciences in 2008. The cultivars are selected from the population of ‘Muscat Hamburg’ (Vitis vinifera) ×V. amurensis. They are extended to most provinces in North of China because they have strong resistance to cold and disease and need not be buried in soil in winter. To better understand the effect of cropload on volatile compounds during wine-making, we surveyed volatiles composition and content of different cropload level in 3-years-old ‘Beihong’ and ‘Beimei’ vines which planted in east foot of Helan mountain of Ningxia (EHN).

Vitis vinifera is one of the most diffused grapevines over the word and it is the raw material for high quality wines production. The availability of more resistant interspecific hybrid vine varieties, developed from crosses between Vitis vinifera and other Vitis species, has generating much interest, also due to the low environmental effect of production. However, hybrid grape wine composition and varietal differences between interspecific hybrids are not well defined. Different studies revealed that wine consumption has health effects due to its high content of antioxidants, as phenolic compounds. In particular, simple phenols are appreciated not only for their physiological health benefits, including antioxidant, anti-inflammatory and cardioprotective effects, but also because they affect wines organoleptic profile and have a significant role in defining their nutritional characteristics.