Influência de revestimentos comestíveis e refrigeração na conservação da amora-preta

Abstract

Blackberry is a short lived post-harvest fruit; it has a fragile structure and high breathing/respiratory activity. For these reasons, technologies that improve its shelf life should be studied, in order to ensure longer preservation and quality. The aim of this study was to evaluate the post-harvest lifetime, of the Tupy cultivar blackberry, by applying different biodegradable films, packing in PET (polyethylene terephthalate) plastic containers and, also, to determine the influence of cold storage at 0 and 10°C. Two ex periments were carried out with treatments application (control), chitosan 1,5% solubilized in ascorbic acid 0.8%, cassava starch 2.5% and water kefir grains 20%, stored at temperatures of 0 and 10°C, being used as plasticizers glycerol 1% in Experiment I (EI) and sorbitol/glycerol 1% (m/v) in Experiment II (EII), for each coating. Physical and chemical analyses were carried out (fruit weight/mass loss, firmness, reducing sugars, total sugars, pH, titratable acidity, total soluble solids, ratio and anthocyanins) and decay incidence. The temperatures evaluated, in addition to applications of the coating, were decisive for the quality of fruits during storage. In the conditions of this study, fruits coated with chitosan 1,5% and sorbitol/glycerol 1% (m/v), packed in temperatures of 0°C, showed lower weight loss and decay incidence, the slightest variation in levels of RS, TS and TSS, the smallest increase in pH values and the lowest reduction of TTA concentration, keeping fruit quality with up to 18 days of storage. The temperature of 0°C is the best storage condition of the fruit, because it maintains the physical and chemical characteristics for more quality for consumption. The storage of fruits at 10°C was no t satisfactory, since at this temperature, the fruit quality remained only 5-6 days of storage, with the application of chitosan, starch and kefir coatings. The coating with kefir was what kept most of the physical and chemical characteristics of fruit quality, under those conditions. The concentration values of total anthocyanins increased during the storage period at 10°C. Fruit harvests, in different years, may cause differences in results. This was true in the incidence of decay, caused by the climatic conditions of each year, and the largest incidence of fruit decay was detected in the harvest of December, 2009 crop.