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Peng C.-T.,Northwest University, China | Wen Y.,Northwest University, China | Tao Y.-S.,Northwest University, China | Tao Y.-S.,Shaanxi Engineering Research Center for Viti Viniculture | Lan Y.-Y.,Northwest University, China
Journal of Agricultural and Food Chemistry | Year: 2013

The influence of a prefermentative freezing process on changes of aromatic characteristics and volatile compounds in Meili wines was studied to optimize freezing parameters and reveal the mathematical relationship between aromatic characteristics and volatile compounds. The wines obtained were characterized by sensory evaluation and stir bar sorptive extraction (SBSE) followed by a thermal desorption-gas chromatography-mass spectrometry analysis. A total of 28 aromatic descriptors from 6 categories of wine aroma terminology were identified by judging with high "modified frequency (MF%)". In addition, 19 varietal aroma compounds and 36 fermentation aroma compounds were quantitated, followed by the determination of odor activity values (OAVs). On the basis of the data obtained, principal component analysis (PCA) was used to find the relationship between characteristic aroma terms and different freezing conditions, and then partial least-squares regression (PLSR) was proposed to establish the mathematical relationship between the resulting terms and impact odorants. Natural thawing treatment on frozen must resulted in higher aroma quality with higher extraction of varietal aroma compounds. Lower frozen maceration temperature contributed to higher esters and organic acids. Impact aroma compounds were related to models for floral, sweet fruit, temperate fruit, and vegetal, whereas the model of rose and strawberry contained only varietal volatile compounds, and temperate fruit could be regressed by impact fermentation aroma compounds. © 2013 American Chemical Society. Source

Wang C.,Northwest University, China | Liu Y.,Northwest University, China | Liu Y.,Shaanxi Engineering Research Center for Viti Viniculture
Food Microbiology | Year: 2013

The evolution of yeast species and Saccharomyces cerevisiae genotypes during spontaneous fermentations of Muscat blanc planted in 1957 in Jingyang region of China was followed in this study. Using a combination of colony morphology on Wallerstein Nutrient (WLN) medium, sequence analysis of the 26S rDNA D1/D2 domain and 5.8S-ITS-RFLP analysis, a total of 686 isolates were identified at the species level. The six species identified were S. cerevisiae, Hanseniaspora uvarum, Hanseniaspora opuntiae, Issatchenkia terricola, Pichia kudriavzevii (Issatchenkia orientalis) and Trichosporon coremiiforme. This is the first report of T. coremiiforme as an inhabitant of grape must. Three new colony morphologies on WLN medium and one new 5.8S-ITS-RFLP profile are described. Species of non- Saccharomyces, predominantly H. opuntiae, were found in early stages of fermentation. Subsequently, S. cerevisiae prevailed followed by large numbers of P. kudriavzevii that dominated at the end of fermentations. Six native genotypes of S. cerevisiae were determined by interdelta sequence analysis. Genotypes III and IV were predominant. As a first step in exploring untapped yeast resources of the region, this study is important for monitoring the yeast ecology in native fermentations and screening indigenous yeasts that will produce wines with regional characteristics. © 2012 Elsevier Ltd. Source

Meng J.-F.,Northwest University, China | Ning P.-F.,Northwest University, China | Xu T.-F.,Albert Ludwigs University of Freiburg | Zhang Z.-W.,Northwest University, China | Zhang Z.-W.,Shaanxi Engineering Research Center for Viti Viniculture
Molecules | Year: 2013

Rain-shelter cultivation is an effective cultural method to prevent rainfall damage during grape harvest and widely applied in the Chinese rainy regions. In this study we investigated the effect of rain-shelter cultivation on grape diseases and phenolic composition in the skins of Vitis vinifera cv. Cabernet Gernischet grape berries through the comparison with open-field cultivation at two vintages (2010 and 2011). The results showed that rain-shelter cultivation reduced the incidence of grape diseases significantly and delayed the maturation of Cabernet Gernischet fruits. With regards to most of the phenolic compounds identified in this study, their content in grape samples under rain-shelter cultivation was decreased compared to those under open-field cultivation. However, rain-shelter cultivation stimulated the accumulation of dihydroquercetin-3-O-rhamnoside in grape skins during grape maturation. These were related with micrometeorological alterations in vineyards by using plastic covering under rain-shelter cultivation. It suggests the rain-shelter cultivation makes possible the cultivation of "Cabernet Gernischet" grapes in an organic production system, for providing a decrease in the incidence of diseases and the dependence on chemical pesticides in the grape and wine industry. © 2013 by the authors. Source

Jiang B.,Northwest University, China | Zhang Z.-W.,Northwest University, China | Zhang Z.-W.,Shaanxi Engineering Research Center for Viti Viniculture | Zhang X.-Z.,Northwest University, China
Journal of the Chemical Society of Pakistan | Year: 2011

Two vineyards with different terrains (site A: 1280 m versus site B: 909 m) in Xiangning County of Shanxi Province located in Loess Plateau region were chosen to study phenolic compounds and antioxidant activities of Cabernet Sauvignon wines by different analytical methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH·), cupric reducing antioxidant capacity (CUPRAC), superoxide radical-scavenging activity (SRSA) and ferric thiocyanate (FTC). The results showed that the contents of total phenolics, flavonoids and flavanols in site B wine were significantly higher than those of site A wine, the content of anthocyanins was basically identical; the antioxidant activity of site B wine was higher, but the magnitude of the difference existed in different analytical methods, especially for DPPH and CUPRAC assays; the contents of 9 individual phenolics of site B wine were basically higher than those of site A wine. The fact is concluded that different terrain truly affected on quality of wines, the contents of phenolic compounds and antioxidant activity of wine from lower altitude vineyard were relatively higher than those from higher altitude vineyard. Source

Meng J.-F.,Northwest University, China | Xu T.-F.,Albert Ludwigs University of Freiburg | Wang Z.-Z.,Northwest University, China | Fang Y.-L.,Northwest University, China | And 5 more authors.
Journal of Pineal Research | Year: 2014

Grapes are an important economic crop and are widely cultivated around the world. Most grapes are grown in arid or semi-arid regions, and droughts take a heavy toll in grape and wine production areas. Developing effective drought-resistant cultivation measures is a priority for viticulture. Melatonin, an indoleamine, mediates many physiological processes in plants. Herein, we examined whether exogenously applied melatonin could improve the resistance of wine grape seedlings grown from cuttings to polyethylene glycol-induced water-deficient stress. The application of 10% polyethylene glycol (PEG) markedly inhibited the growth of cuttings, caused oxidative stress and damage from H2O2 and O2-, and reduced the potential efficiency of Photosystem II and the amount of chlorophyll. Application of melatonin partially alleviated the oxidative injury to cuttings, slowed the decline in the potential efficiency of Photosystem II, and limited the effects on leaf thickness, spongy tissue, and stoma size after application of PEG. Melatonin treatment also helped preserve the internal lamellar system of chloroplasts and alleviated the ultrastructural damage induced by drought stress. This ameliorating effect may be ascribed to the enhanced activity of antioxidant enzymes, increased levels of nonenzymatic antioxidants, and increased amount of osmoprotectants (free proline). We conclude that the application of melatonin to wine grapes is effective in reducing drought stress. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Source

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