Effect of temperature on drying kinetic in foam mat and anthocyanin degradation in strawberry

Abstract

The strawberry is a fruit widely consumed throughout the world and of great nutritional wealth, being used as an ingredient in the elaboration of a variety of products. However, it is a highly perishable fruit, requiring technologies to increase its useful life. Therefore, the objective of this work was to evaluate the drying kinetics and the effect of temperature on the total anthocyanin content of the strawberry. Thus, strawberry pulp was obtained and destined for the analysis of the total anthocyanin and moisture contents. 1% albumin was added to the pulp and subjected to beating to produce a foam. The foam was placed in trays in a convective dryer at temperatures of 55, 60, 65, 70 and 75 °C, to constant weight. The Henderson and Pabis, Lewis and Page models were fitted to the moisture ratio data and the generalized model of the moisture ratio as a function of temperature and drying time constructed. The total anthocyanin and moisture contents of the powders were determined. The Page model was chosen to represent the drying kinetics of the strawberry pulp, since it presented the highest value for the adjusted coefficient of determination and the lowest standard error of the regression. The generalized model obtained was satisfactory to predict the moisture ratio of the strawberry pulp, presenting an R2 of 0.98. The total anthocyanin content of the fresh pulp was 235.03 mg / 100 g and reduced by approximately 50% for all the temperatures evaluated.