Avaliação da qualidade de morangos recobertos com diferentes filmes biodegradáveis durante sua ‘’shelf-life’’

Abstract

The postharvest losses of fruit tend to raise the price of products and reduce the supply to consumers. The main causes of losses are: harvesting, transportation, handling and inappropriate storage. The application of edible films and coverings along with storage temperature reduction creates one of the most used methods for postharvest preservation of products with low shelf life like fruits and vegetables. Strawberry is a very delicate fruit, tasty and preferably consumed in natura, thus, becomes favourable the use of edible coverings with the main purpose of increasing the storage life and marketing, inhibiting microbial growth. The present study was aimed to evaluate and classify the bacterial growth in covered strawberries with biodegradable films of starch acetate and cassava starch, added monascus and potassium sorbate in 19 days of storage with an average temperature of 7 C. Microbiological tests were performed on days 0, 3, 7, 10, 15 and 19, intending to quality control to monitor the deterioration process and fruit behavior over the stored days. Aerobic mesophile count was in traditional plate count agar (PCA) incubated at 36 ± 0.5 C for 48 ± 3 hours. The psychotropic count was in PCA agar incubated at 0-10 C for 7 to 8 days. The standard fungi and yeasts counts were done by spreading on PDA agar incubated at 25 C for 5 days. Coliforms were determined by the NMP technique in Brilliant Green Bile Broth (BVB) to confirm total coliforms at 37 C, and Escherichia Coli Broth (EC) to confirm coliforms at 45 C for 48 hours both. Were evaluated the presence of Salmonella sp. and the following physicochemical characteristics: weight loss, pH, soluble solids (°Brix), titratable acidity, maturation index, water activity, texture and sensory analysis. During the storage, there was fresh mass loss. There was no significant difference in the change in pH in the days of storage. In the titratable acidity was a variation of 0.017 g citric acid / 100 g of sample. Strawberries coated with starch obtained higher maturity value, this implies a better consumer taste acceptability. The soluble solids content was not influenced by the covers. The most affected physicochemical factor was the firmness, but there was great resistance of the covered strawberries with edible coatings. The results with strawberries coated with edible films had better acceptability than strawberries without coverage. The result for Salmonella sp was absent in all samples. Microbiological analyzes got better results in strawberries coated with films added monascus starch and potassium sorbate for total coliforms at 45 C were present in all samples with and without coverage.