RESUMO

The technological and polyphenolic parameters of grapes for juice processing obtained from successive harvests were studied in semi-arid tropical viticulture. Red grapes "BRS Violeta" and "Isabel Precoce" were harvested during the same year and analyzed based on a multivariate approach that included climatic variations. The grapes were marked by variations in flavonoid compounds, particularly anthocyanins. Temperature, global radiation, air velocity and evapotranspiration rates were associated with higher accumulation of bioactive polyphenols in grape berries and juices. The temperatures in February were associated with higher antioxidant activity in grape peels, while the highest thermal amplitude in August and November favored the accumulation of anthocyanins up to 564 mg kg-1. Flavanols and procyanidin compounds were more abundant in seeds when the maximum thermal amplitude was 13.8 °C. The climatic data together with the polyphenolic results point out useful information about appropriate periods for harvesting grapes with high phenolic content in tropical areas.

Assuntos

RESUMO

An automated headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-ion trap/mass spectrometry (GC-IT/MS) was developed in order to quantify a large number of volatile compounds in wines such as alcohols, ester, norisoprenoids and terpenes. The procedures were optimized for SPME fiber selection, pre-incubation temperature and time, extraction temperature and time, and salt addition. A central composite experimental design was used in the optimization of the extraction conditions. The volatile compounds showed optimal extraction using a DVB/CAR/PDMS fiber, incubation of 5 ml of wine with 2g NaCl at 45 °C during 5 min, and subsequent extraction of 30 min at the same temperature. The method allowed the identification of 64 volatile compounds. Afterwards, the method was validated successfully for the most significant compounds and was applied to study the volatile composition of different white wines.

Assuntos

RESUMO

Nowadays, the agro-industrial processing produces millions of tons of wastes. Many of them are rich in bioactive compounds, being a potential natural source of these substances. This study aimed to evaluate the content of total phenolics, antioxidant activity and phenolic composition of residues generated by three Brazilian agribusiness: Isabel grape pomace (PI) (Vitis labrusca), Verdejo grape pomace (PV) (Vitis vinifera) and guava pomace (PG) (Psidium guajava). The results of total phenolics content (mg GAE g-1) found in the ethanol and aqueous extracts of residues were: PV (20.94±0.46; 8.03±0.43)>PI (16.57±0.19; 4.41±0.01)>PG (3.41±0.09; 1.88±0.06). High antioxidant activity of these extracts, particularly PV and PI, was found by the methods DPPH , ABTS and beta-carotene bleaching method. A strong positive correlation between antioxidant activity and content of total phenolic compounds was found. The following phenolic compounds were found by gas chromatography with mass spectrometry (GC-MS): gallic acid, epicatechin, quercetin (PV, PI and PG); isovanilic acid (PI, PG), p-coumaric acid (PI), caffeic acid and resveratrol (PV, PI). The results show that these residues, particularly the wineries, are rich in bioactive substances and should be exploited by the food industry and pharmaceuticals.

Atualmente, são produzidas milhões de toneladas de resíduos provenientes do processamento agroindustrial. Muitos deles são ricos em compostos bioativos sendo potenciais fontes naturais dessas substâncias. Assim, este trabalho teve como objetivo avaliar o teor de compostos fenólicos totais, a atividade antioxidante e a composição fenólica de três resíduos gerados por agroindústrias brasileiras: bagaço de uva Isabel (BI) (Vitis labrusca), bagaço de uva Verdejo (BV) (Vitis vinifera) e bagaço de goiaba (BG) (Psidium guajava). Os resultados do teor de compostos fenólicos totais (mg GAE g-1) encontrados nos extratos etanólicos e aquosos dos resíduos foram, respectivamente: BV (20,94±0,46; 8,03±0,43)> BI (16,57±0,19; 4,41±0,01)> BG (3,41±0,09; 1,88±0,06). Alta atividade antioxidante, principalmente em BV e BI, foi verificada nos ensaios realizados (ABTS , DPPH e auto-oxidação do sistema beta-caroteno/ácido linoléico). Uma forte correlação positiva entre atividade antioxidante e o teor de compostos fenólicos totais foi encontrada. Os compostos fenólicos encontrados, por cromatografia gasosa com espectrometria de massas (CG-EM), foram: ácido gálico, epicatequina, quercetina (BV, BI e BG); ácido isovanílico (BI, BG); ácido p-cumárico (BI); ácido caféico e resveratrol (BV, BI). Esses resultados mostram que os resíduos agroindustriais analisados, particularmente os vinícolas, são ricos em substâncias bioativas e podem ser explorados pela indústria de alimentos e farmacêutica.

RESUMO

Nowadays, the agro-industrial processing produces millions of tons of wastes. Many of them are rich in bioactive compounds, being a potential natural source of these substances. This study aimed to evaluate the content of total phenolics, antioxidant activity and phenolic composition of residues generated by three Brazilian agribusiness: Isabel grape pomace (PI) (Vitis labrusca), Verdejo grape pomace (PV) (Vitis vinifera) and guava pomace (PG) (Psidium guajava). The results of total phenolics content (mg GAE g-1) found in the ethanol and aqueous extracts of residues were: PV (20.94±0.46; 8.03±0.43)>PI (16.57±0.19; 4.41±0.01)>PG (3.41±0.09; 1.88±0.06). High antioxidant activity of these extracts, particularly PV and PI, was found by the methods DPPH , ABTS and beta-carotene bleaching method. A strong positive correlation between antioxidant activity and content of total phenolic compounds was found. The following phenolic compounds were found by gas chromatography with mass spectrometry (GC-MS): gallic acid, epicatechin, quercetin (PV, PI and PG); isovanilic acid (PI, PG), p-coumaric acid (PI), caffeic acid and resveratrol (PV, PI). The results show that these residues, particularly the wineries, are rich in bioactive substances and should be exploited by the food industry and pharmaceuticals.

Atualmente, são produzidas milhões de toneladas de resíduos provenientes do processamento agroindustrial. Muitos deles são ricos em compostos bioativos sendo potenciais fontes naturais dessas substâncias. Assim, este trabalho teve como objetivo avaliar o teor de compostos fenólicos totais, a atividade antioxidante e a composição fenólica de três resíduos gerados por agroindústrias brasileiras: bagaço de uva Isabel (BI) (Vitis labrusca), bagaço de uva Verdejo (BV) (Vitis vinifera) e bagaço de goiaba (BG) (Psidium guajava). Os resultados do teor de compostos fenólicos totais (mg GAE g-1) encontrados nos extratos etanólicos e aquosos dos resíduos foram, respectivamente: BV (20,94±0,46; 8,03±0,43)> BI (16,57±0,19; 4,41±0,01)> BG (3,41±0,09; 1,88±0,06). Alta atividade antioxidante, principalmente em BV e BI, foi verificada nos ensaios realizados (ABTS , DPPH e auto-oxidação do sistema beta-caroteno/ácido linoléico). Uma forte correlação positiva entre atividade antioxidante e o teor de compostos fenólicos totais foi encontrada. Os compostos fenólicos encontrados, por cromatografia gasosa com espectrometria de massas (CG-EM), foram: ácido gálico, epicatequina, quercetina (BV, BI e BG); ácido isovanílico (BI, BG); ácido p-cumárico (BI); ácido caféico e resveratrol (BV, BI). Esses resultados mostram que os resíduos agroindustriais analisados, particularmente os vinícolas, são ricos em substâncias bioativas e podem ser explorados pela indústria de alimentos e farmacêutica.