Análise multiparamétrica da qualidade dos frutos, mostos e vinhos de jabuticaba
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2012-06-28
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Universidade Federal de Goiás
Resumo
Chemical parameters were monitored during the jabuticaba s development,
fermentation and ageing of its wine, by quantitative 1H NMR, spectrophotometric assays
and standard methods of analysis. Data collected were analysed by variance (ANOVA),
principal components (PCA), hierarchical cluster (HCA) and canonical correlation
analyses (CCA). Jabuticaba s development was analysed in order to identify the optimal
harvest period for winemaking. Total acidity decreased 70.5%, whereas reducing
sugars increased about threefold in pulps up until the full ripe stage. Anthocyanin levels
underwent a sharp increase in the skins reaching 22.0 mg/g at complete maturation.
Tannins and total phenols showed no significant differences in their levels between ripe
and full ripe stages. The PCA and HCA distinguished two sample groups, the first
comprised of samples from the first four days of fermentation characterized by high
levels of fructose, glucose, anthocianins and colour intensity (19.90 g/kg; 36.95 g/kg;
177.88 mg/L and 8.6). The second cluster consisted of samples from days 5 to 14 with
higher levels of ethanol, glycerol, methanol, acetic acid (75.02; 3.13; 0.19 and 0.99
g/kg), hue and pH (1.25 and 3.49). The canonical correlation analysis confirmed the
influence of alcohols (ethanol, methanol and glycerol), organic acids (citric, succinic and
acetic acids), pH and titratable acidity on the extraction and stability of anthocyanins
and copigments. Three clusters were identified by the multivariate statistical analysis of
red wine samples from 2001 to 2010. Cluster I, wines from 2001, 2002, 2003 and 2006,
was characterized by chemical age 1 and 3, hue (1.02; 0.89; 1.83), acetaldehyde and
alcohols (0.04 and 0.24 g/L). The wines from 2005, 2007 and 2008 formed the second
cluster and presented the lowest content of superior alcohols (0.14 g/L). The third
cluster was comprised by wines from 2009 and 2010, which contained higher levels of
methanol, acetic and latic acids (0.12; 1.24; 0.35 g/L), and the highest pH (3.96). The
canonical correlation analysis revealed that chemical age 1, 2 and 3 correlate negatively
with anthocyanins, pH and titratable acidity, confirming the importance of pH and acidity
in the anthocyanins stability and polimerization.
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FORTES, Gilmara Aparecida Corrêa. Multiparametric analysis of quality of fruits, musts and wines jabuticaba. 2012. 62 f. Dissertação (Mestrado em Educação em Química) - Universidade Federal de Goiás, Goiânia, 2012.