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Food Chem ; 305: 125484, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514048


Grape pathogenesis-related proteins can cause haze in wine that is undesirable for consumers. Bentonite is used to remove these proteins but is a non-renewable natural material and reduces wine volume due to poor settling. As a potential bentonite alternative, grape seeds powder (GSP) was added to four wines and two grape juice varieties. Addition to wine required high doses (25-32 g/L) for protein removal and haze prevention and this induced changes to wine composition. By contrast, addition to grape juice prior to fermentation required substantially lower doses of GSP (5 g/L) to prevent haze formation. Further 20 g/L of GSP added to the must induced less changes to wine composition than direct addition of GSP to the wine. No changes were recorded in the efficacy of protein removal by changing the GSP source (red or white grape marc), or by using grape seed roasting. Despite the need for additional trials, these preliminary results suggest that GSP may be considered as a viable alternative to bentonite especially when added to juice prior to fermentation.

Food Chem ; 288: 78-85, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-30902317


Oxidative spoilage is a phenomenon that can occur both in winemaking and during bottle storage. The complexity of oxidative spoilage makes it difficult to identify all the products from oxidation processes, especially in bottled wines with varying degrees of oxidative spoilage, i.e., "random oxidation". To this end, this study sought to obtain a deeper insight into the chemistry of white wine samples to identify compounds able to discriminate the different oxidative statuses. The results of metabolomics and VIP analysis outlined molecules such as 3-methylcatechol, cyanidin 3-O-6″-p-coumaroyl-glucoside, delphinidin 3-O-glucoside, quercetin 3-O-glucosyl-xyloside, dihydroquercetin, and quercetin 3-O-glucuronide to be discriminant in the detection of the oxidative status of the white wines under study, which were preliminarily classified in low and high oxidation classes by means of sensory analysis. Parameters such as total and free sulfur dioxide content and browning and pinking measurements were confirmed to remain significantly correlated with oxidation-related issues.

Metabolômica , Fenóis/análise , Vinho/análise , Antocianinas/análise , Cromatografia Líquida de Alta Pressão , Análise Discriminante , Glucosídeos/análise , Análise dos Mínimos Quadrados , Oxirredução , Fenóis/química , Espectrometria de Massas por Ionização por Electrospray , Dióxido de Enxofre/análise