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Lan Y.Y.,Northwest University, China | Tao Y.S.,Northwest University, China | Tao Y.S.,Shaamd Engineering Research Center for Viti Viniculture | Tian T.,Northwest University, China | And 2 more authors.
South African Journal of Enology and Viticulture | Year: 2014

In this study, the effect of a pre-fermentative freezing treatment on quality attributes of 'Meffi' rosé wine was assessed. Prior to fermentation, 'Meffi' grapes (berries and must) were subjected to a freezing treatment considering factors of freezing temperatures, freezing time, and thawing method. Colour-related indices were measured by spectral methods. Wine aroma characteristics and sensory attributes were assessed by trained paneffists. The results revealed that lower freezing temperature and longer freezing time had positive effects on wine quality attributes. The treatment of frozen berries might help extract colourrelated compounds. Microwave thawing improved wine colour, but decreased taste quality. In the work, the MF-10°C/6 h treatment (microwave-thawed berries that had been frozen at -10°C for 6 h) contributed to the best colour characteristics, whereas the NP-20°C/4 h treatment (naturally-thawed must that had been frozen at -20°C for 4 h) contributed to the best taste attributes.

Luan L.-Y.,Northwest University, China | Zhang Z.-W.,Northwest University, China | Zhang Z.-W.,Shaamd Engineering Research Center for Viti Viniculture | Xi Z.-M.,Northwest University, China | And 3 more authors.
South African Journal of Enology and Viticulture | Year: 2013

Anthocyanins are important components in the skins of grapes and in the development of wine colour. Various environmental factors cause poor coloration in some areas, even for the same cultivars planted in different production areas. The objective of this study was to evaluate the effect of exogenous brassinosteroids (BR) on the accumulation of anthocyanins and gene expression of anthocyanin biosynthesis in wine grape berry skins. The results show that total anthocyanin content in BR-treated grapes was higher than that in the control (CT) grapes, and that 0.4 mg(L was the most effective treatment concentration. The effect of BR on downstream genes was more effective than that on upstream genes. Full coloration of BR-treated grapes was achieved seven days earlier than in the case of CT. Moreover, BR enhanced the transcript level of the downstream genes of anthocyanin biosynthesis, which caused the total anthocyanin content to increase. The induction of structural and regulatory genes of the flavonoid pathway suggests that the interrelationships between developmental and environmental signalling pathways were magnified by BR treatment, which actively promoted fruit coloration, namely anthocyanin biosynthesis.

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