Gilberto Costa Braga

Atividade antioxidante, composição química e conservação do maracujá-amarelo embalado com filme PVC

The aim of this study was to evaluate the chemical characteristics and conservation of yellow passion fruit packed with PVC film during refrigerated at 5 oC. Antioxidant activity (DPPH and TEAC), total phenolic compounds, β-carotene and ascorbic acid of the fruit juice were the chemical parameters. Estimations of weight loss, wrinkling, color and symptoms of pathogens were used in the conservation study. The evaluations were performed in 10-day intervals for 40 days. According to the results, the total phenolic content increased during storage, varying between 20.10 and 21.29 mg EAG 100 mL-1. The contents of ascorbic acid increased until the 20th day of storage (33.58 mg 100 mL-1), but followed with decreases until the 40th day (21.67 mg 100 mL-1). Regardless of the use of PVC, β-carotene did not change during storage. The TEAC and DPPH antioxidant activity in juice decreased during storage. The DPPH and TEAC antioxidant activity did not correlate positively with total phenolics, suggesting that phenolic compounds do not contribute to the antioxidant activity of passion fruit juice. The use of PVC packaging did not influence positively on the antioxidant activity and the contents of total phenolics and ascorbic acid of yellow passion fruit juice during storage. The PVC did not inhibit the pathogens-degradation symptoms for up to 30 days of storage, at 5 oC, but reduced the weight loss and wrinkling of the fruit, providing optimal conditions of merchantability for up to 20 days.

Teores de antocianinas, fenóis totais, taninos e ácido ascórbico em uva 'bordô' sobre diferentes porta-enxertos

Anthocyanins, total phenols, tannins and ascorbic acid in cv. Bordo grape on different rootstocks This study aimed to evaluate the content of anthocyanins, total phenols, tannins and ascorbic acid in grape grown onto ‘420A’, ‘IAC-766’ and ‘Riparia-of-Traviu’ rootstocks in three different harvest periods. The experiment was conducted in ‘Bordo’ grapes vineyard in Missal city, Parana West, in the 2007/2008 harvest. The rootstock effect was evaluated in three periods after flowering: 90 days, with ripening berries , tending to a definite purple; 100 days, with berries completely purple , and 110 days, with berries overripening. The experiment was arranged in a split plot design in randomized blocks. The variables soluble solids, titratable acidity, total phenols index, anthocyanins, tannins and ascorbic acid were analyzed. The results showed that in the rootstocks ‘420A’ and ‘IAC-766’, the ‘Bordo’ grape showed similar responses for anthocyanins, tannins, acidity and soluble solids accumulation, but the contents of phenolic compounds in the pulp and epidermis of berries were higher in ‘420A’. On the rootstock ‘Riparia-do-Traviu’, the ‘Bordo’ grape showed lower accumulation of anthocyanins, total phenols and tannins in the epidermis. Higher accumulations of ascorbic acid were found in ‘Bordo’ grapes on the rootstock ‘IAC-766’. There is evidence suggesting that the ‘Riparia-do-Traviu’ rootstock as inferior to others in nutritional and enological aspects.

PHENOLIC COMPOSITION AND ANTIOXIDANT CAPACITY OF AQUEOUS AND ETHANOLIC EXTRACTS OF BLACKBERRIES

The objective of this work was to evaluate the content of phenolic compounds, anthocyanins and flavonoids extracted with 80% ethanol and water, and antioxidant capacity (DPPH and ABTS) of five blackberry cultivars produced in Western Parana, Brazil. Brazos, Tupy, Arapaho, Choctaw and Guarani blackberries were studied. Soluble solids, titratable acidity and ascorbic acid of fruits were also characterized. Total phenolic compounds ranged from 8.23 to 14.98 mg GAE g-1 (f.w.) and Arapaho cultivar exhibited the highest contents in both solvents. Anthocyanins ranged from 2.57 to 9.42 mg ECy3glu g-1 (f.w.), being the solvent ethanol 80% more efficient than the water, and Choctaw cultivar showing the highest content. Flavonoids ranged from 0.46 to 1.14 mg EQ g-1 (f.w.) and Guarani cultivar showed the highest content. High linear correlations were found between total phenolics and antioxidant capacity in both extraction solvents. However, linear correlations between anthocyanins and antioxidant capacity were observed only for the aqueous solvent. Ascorbic acid ranged from 87.87 to 134.09 mg 100 g-1, with emphasis on Brazos cultivar. The aqueous extract showed greater ability to scavenge ABTS radical, but the ethanolic extract was more efficient for the DPPH radical. Blackberries produced under Western Parana conditions showed high levels of antioxidants with emphasis on Arapaho cultivar. This study showed that water and ethanol solvents influence different results on phenolic composition and antioxidant activity of blackberries.

Heat shock and salicylic acid on postharvest preservation of organic strawberries

Heat shock and salicylic acid have been studied on shelf-life extension of fruits. The benefits of these techniques have been related to their effect on inducing physiological defense responses against the oxidative stress and pathogen development. The objective of this study was to evaluate the effect of heat shock and salicylic acid on the postharvest preservation and contents of total phenolics, anthocyanins, ascorbic acid, fresh weight loss and microbiological quality of organic strawberries cv. Dover. Strawberries produced organically and stored at 5 °C were subjected to heat shock (45 °C ± 3 °C for 3 h), application of salicylic acid (soaking in 2.0 mmol L -1 solution), heat shock in combination with salicylic acid and control. After treatment, the fruits were packed and stored in a climatic chamber at 5 oC ± 2 oC. At 1, 7 and 14 days, the experimental units were removed from refrigeration and kept at room temperature of approximately 20 oC for two days. There was no effect of treatments on fresh weight loss, incidence of pathogens or chemical variations in strawberry fruits during the storage period. In natural conditions, organically grown strawberries remained in good condition for sale up to seven days of storage in all treatments.