Evaluation of pre-treatment and application of edible coatings in fruits drying / Avaliação de pre-tratamentos e aplicação de coberturas comestiveis na secagem de frutas

AUTOR(ES)

Nenis Maria Eik

DATA DE PUBLICAÇÃO

2008

RESUMO

Most vegetables and fruits are highly perishable due to a high water conten, which makes it difficult to trade, since seasonality and distance between markets demand costly refrigerated storage and transportation. Increasing shelf life and availability throughout the year by processing reduces losses by marketing of fresh foods. This research aimed at evaluating the influence of pre-treatment and application of edible coatings on the kinetics of drying and their effects on the physical and nutritional quality of dehydrated fruits. In the first stage of this study, persimmon fruit was used in slices, that were pre-treated in various ways, i.e. bleaching with a solution of citric acid (0.2% w/w) and ascorbic acid (0.1 % w/w), bleaching with steam, coating with amaranth flour (4% w/w) and coating with pectin (2% w/w). After each pre-treatment the slices were dehydrated using a convective heated air dryer. In a second series of tests, figs were pre-treated by bleaching with a solution of citric acid (0.2% w/w) and ascorbic acid (0.1 % w/w), coating with amaranth flour (4% w/w) and coating with pectin (2% w/w) and dehydrating in a convective heated air dryer. Concentration, temperature and bleaching parameters were chosen, as well as the time of preparation and application of the coating. The drying kinetics were determined as a function of air velocity and temperature. The drying efficiency was determined by the drying rates obtained with the different pretreatments and conditions. The shrinkage of the slices was determined by measuring density and thickness of samples collected during the drying process. For evaluation of the quality of the fresh product and the dry product, analyses of polyphenols, total carotenoids and color were carried out. Dried persimmon fruit was equally evaluated for its quality during four months of storage

ASSUNTO(S)

nutritional properties storage propriedades nutricionais coberturas comestiveis edible coatings frutas fruits drying secagem

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