Casca de jabuticaba (Plinia jaboticaba (Vell.) Berg): processo de secagem e uso como aditivo em iogurte

Abstract

The jabuticaba is a fruit native of Brazil, its being found in a wide territorial range in the country. The jabuticaba skin stands for up to 43% of the fruit, its being rich in fibers and minerals in addition to high content of phenolic compounds, which are antioxidant substances. The use of these residues deserves attention, for being a possible natural dye with a good content of anthocyanins and still would be a way of aggregating value to the fruit jabuticaba. Nevertheless, one of the drawbacks to the storage of the skins, it is high water content, needing, therefore, of drying processes which make its conservation viable without leading to the losses of their nutritive and antioxidant quality. In this work, the influence of different drying temperatures upon the contents of nutrients and antioxidant compounds was investigated. In addition, the anthocyanin extract and freeze-dried jabuticaba skin flour were used as dye for yogurts, verifying its acceptance and studying the stability of them, in a given storage time. Jabuticaba skins, Plinia jaboticaba (Vell.) Berg genotype Sabará, were dried by lyophilization and at three temperature de 30, 45 e 60 ºC with the purpose of obtaining the flour of this material by a cheaper process, since freeze-drying is a relatively expensive drying process. Next, ground and stored in tightly closed flasks, protected from light and analyzed as to the centesimal composition, vitamin C, phytate, polyphenols, anthocyanins and antioxidant activity. The anthocyanin extracts were obtained by grinding 1 g of flour with 15 mL of acidified ethanol for 12 h at 4 oC protected from light. The yogurt was made in a conventional way and added of the skin flour at the concentrations of 0.1; 0.5; 1.0; 1.5 and 2.0% and of the anthocyanin extracts at the concentrations of 0.5; 1.0; 1.5; 2.0 and 2.5%. it was found that the drying process little affect the centesimal composition of the flours, there being no significant difference for ether extract and ashes and very small differences for crude protein, dietary fibers and nitrogen-free extract. The freeze-dried skins presented the highest contents fro all the bioactive compounds studied, followed by the drying at 45 ºC. The score given by the sensorial analysis in a general way, lay between 6 (I liked slightly) and 7 (I liked moderately), except for color and appearance of the yogurts added of 0.1% of jabuticaba skin flour which were given lower scores. However, for the anthocyanin extract, the highest scores (6 - I liked slightly) were given to the lower concentrations of 0.5 to 1.5%. Color retention for all the yogurts was higher than 70% and the mean of half-life time greater than 2,500 h which are deemed high, for yogurts have a validity of only 1,080 h. Therefore, it follows that the use of jabuticaba skins as additives for yogurts can be an alternative to aggregate value to the fruit.