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Increasing recent interest in nutraceuticals and functional foods has led researchers to investigate the antioxidant potential of several fruits. This article evaluates the antioxidant potential and reactivity based on luminol-enhanced chemiluminescence capacity of peach extracts (peels and fleshes) and the contribution of a major compound present in these extracts to antioxidant potential and reactivity. The results obtained showed that the extracts of peels and fleshes of Maciel, Leonense, and Eldorado peach cultivars present free radical scavenging activity in all concentrations tested, with a concentration-dependent action. The immediate inhibition of chemiluminescence and the duration of this inhibition were significantly higher with the extracts than with the major compound (chlorogenic acid) alone, and it can be due to a synergistic or additive effect of other antioxidants present in the extracts. The 50% inhibitory concentration (IC(50)) values for peach extract and chlorogenic acid were 1.19 microg/mL and 8.43 microg/mL, respectively, when total radical-trapping antioxidant potential was evaluated, whereas IC(50) values of 0.41 microg/mL and 1.89 microg/mL was found when total antioxidant reactivity was evaluated in peach extract and chlorogenic acid, respectively. Chlorogenic acid presented a good contribution to antioxidant reactivity and potential, but the fruit extracts provide better antioxidant action. Peach could be of great interest as an important antioxidant source including chlorogenic acid, and it may provide health-promoting advantages to consumers by intake of this fruit or by utilization of its peels as antioxidant sources in industry.

Recebido em 15/7/05; aceito em 2/5/06; publicado na web em 26/9/06 DEVELOPMENT AND VALIDATION OF AN ANALYTICAL METHOD FOR THE DETERMINATION OF HISTAMINE IN WINES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH FLUORESCENCE DETECTION. A rapid and efficient method for the analysis of histamine in wines using HPLC with fluorescence detection after derivatization was developed and validated. The method LOD and LOQ values were 0.25 and 0.50 mg L -1 respectively. The repeatability and intermediary precision for the instrument and for the method presented RSD values of 3.7 and 2.9%, and 6.0 and 5.6%, respectively. The recoveries were 95.5 and 89.9% for the fortification levels of 2 and 10 mg L INTRODUÇÃONos últimos anos, as novas tendências em segurança alimentar e a exigência do consumidor por alimentos saudáveis e de qualidade estão promovendo um aumento na pesquisa por constituintes presentes em alimentos e bebidas que podem afetar a saúde humana. Assim, a presença de substâncias que são fisiologicamente ativas no metabolismo humano tem sido extensivamente estudada em alimentos. Em vinhos, interesse especial tem sido dedicado às aminas bioativas ou biogênicas e, em particular, à histamina 1 . Embora estas substâncias estejam presentes no vinho geralmente em baixas quantidades, elas exibem interação com o metabolismo humano, fato que justifica a pesquisa. A histamina produz dilatação dos vasos sangüíneos e, conseqüentemente, cefaléia. A eliminação ou a redução desta substância nos vinhos tem sido uma prática cada vez mais utilizada em certos países 2 . A presença de histamina em vinhos está sendo relacionada às más condições higiênico-sanitárias no processo de produção, uma vez que esta substância é formada por algumas espécies de microorganismos. Devido a isso, é importante uma verificação do conteúdo de histamina em vinhos como forma de detectar possíveis falhas no processo de produção 3 . Entretanto, a quantificação de rotina destas substâncias não é utilizada no controle de qualidade dos vinhos, principalmente devido às dificuldades analíticas, como presença de interferentes e complexidade da matriz 4 . As técnicas de separação de aminas empregadas para a determinação de histamina em vinho incluem, principalmente, a cromatografia gasosa 5 (GC, "gas chromatography") e a cromatografia líquida de alta eficiência 6-11 (HPLC, "high performance liquid chromatography"), sendo que as duas técnicas são seletivas e sensíveis, permitindo a detecção de pequenas quantidades de aminas. A análise de aminas bioativas em alimentos por HPLC tem aumentado, já que oferece a vantagem de separação e quantificação simultânea de aminas 12 . No entanto, a maioria das aminas não apresenta absorção ultravioleta natural ou fluorescência. Por esta razão, a derivatização química é necessária para detectar as aminas por HPLC 13 . Os agentes derivatizantes mais utilizados na determinação por fluorescência de aminas bioativas são: cloreto de dansyl, ortoftaldeído (OPA) e fluorescamine. A principal vantagem que o reagente OPA apresenta em rela...

The polyvinylpolypyrrolidone (PVPP) is a high molecular weight vinylpyrrolidone polymer (about 1.000.000) and is water insoluble. Ot is a synthetic fining agent that tends to form bonds with phenolic compounds of lower molecular weight (Sims et al., 1995; Donovan et al., 1998), promoting the reduction in the levels of total polyphenols, phenolic acids, procyanidins, catechins, polyphenols, and protein complexes. Mechanism of adsorption of polyphenols on PVPP is similar to the mechanism of flocculation of gelatin and tannin, with formation of hydrogen bonds between the phenolic groups and oxygen of the amine group of the pyrrolidone ring (Togores, 2018). Currently, the pea protein isolate, an adequate alternative to proteins of animal origin or proteins with an allergenic potential

Abstract. The Serra Gaucha has a high rainfall occurrence during the ripening and harvest. It results in higher use of fungicides, being the copper-based ones, the most commonly used. High levels of this metal can cause stress to the yeast, thus, influencing on the fermentation kinetics. The aim of this study was to evaluate the fermentative behavior of oenological yeast in the presence of copper content in the must. The experiment used the following fungicides: Copper Sulfate, Copper Oxychloride and Copper Hydroxide. Samples were inoculated with S. cerevisiae, S. cerevisiae var. bayanus and Torulaspora delbrueckii and the fermentation was plotted for carbon dioxide production by time. The fermentative kinetics were assessed by the following kinetic parameters: the lag phase time, maximum rate of CO2 production and maximum production of CO2. The study showed that T. delbrueckii had higher sensitivity to copper regarding the lag phase. Copper oxychloride promoted greater latency period in yeast T. delbrueckii and S. cerevisiae. All copper fungicides decreased maximum rate of fermentation, and T. delbrueckii was the most affected. The maximum CO2 production during the fermentations significantly differed only in the presence of copper sulphate.

O consumo moderado de vinho reduz significativamente os riscos de doenças cardiovasculares. Este efeito é atribuído aos polifenóis presentes no vinho, em especial ao resveratrol (3,5,4'triidroxiestilbeno), que é uma fitoalexina encontrada em várias partes da videira, principalmente na casca da uva, assim como em outras espécies de plantas. Uvas da cultivar Cabernet Sauvignon foram submetidas à irradiação com luz ultravioleta e maceração carbônica e após fermentadas. Procedeu-se à coleta de amostras durante todo o experimento, as quais foram posteriormente analisadas quanto ao teor de trans-resveratrol através da Cromatografia Líquida de Alta Eficiência. Os resultados do trabalho demonstram que a evolução do conteúdo de transresveratrol foi ascendente durante as fases da fermentação. Diferenças ocorreram no final da fermentação, em que as amostras de vinhos com maceração carbônica apresentaram leve declínio, possivelmente pela atmosfera de CO 2 na qual ficaram armazenadas, inibindo a formação do resveratrol. Ao final da fermentação principal a concentração de trans-resveratrol foi de 15 mg.L-1 em todos os tratamentos, chegando a 1,5 mg.L-1 , em média, no final do período de estocagem.

Ion exchange resins are polymers with high physical and chemical stability, which, upon activation, acquire positive charge (H+) ions which interchange with existing cations during musts or wines treatment. The chemical composition of the grape must, and wines are highly affected by said modifications. This study aimed to evaluate the impact of the cationic resin treatments on the physicochemical and organoleptic characteristics of base white wines for sparkling wine production. Thus for, Chardonnay must was exposed to a cation exchange resin specific for oenological usage, and fermented to obtain wines. Resulting wines included an untreated control sample with pH 3.15 and treated samples with pH 3.08, 3.02 and 2.97. Physicochemical and volatile compounds analyses as well as quantitative sensory evaluations were conducted. The results showed that, on the scenarios tested, treatments with cationic resins before fermentation resulted in wine with higher oxidative stability, with significative variation on the concentration of several volatile compounds that influenced organoleptic perceptions.

Soy protein isolate was evaluated as a potential fining agent as an alternative to the predominant protein commercial fining agents (ovalbumin, porcine gelatin, and pea protein isolate). Two red wines (cv. ‘Merlot’ and cv. ‘Lambrusco Maestri’) were finned, bottled, and analyzed for phenolic content, color, turbidity, and sensory profile. Independent of the protein used, fining promoted a reduction in a majority of the phenolic compound, a slight (but significant) reduction of chromatic properties, and a decrease in the turbidity of the wines. A decrease in astringency, persistence, bitterness, and wine body, as well as an increase in brightness, clarity, and acidity, was also observed in all treatments. The application of soy protein isolates yielded similar results to those obtained with other commercial fining agents, both in the physicochemical and the sensory measures, which favors its usage as an alternative to the traditional fining agents of animal-protein origin.