Secagem do jambo vermelho (Syzygium malaccense) em camada de espuma (foam-mat drying)

Abstract

The red jambo (Sizygium malaccense) has a dark red color in the bark, this characteristic among others, incite research that explores its functional effects. In addition to its fresh consumption, jambo is also used to extract dyes due to the color of its skin. It is a seasonal fruit and very perishable, which makes it difficult to be available throughout the year. One way to make its conservation feasible is by using foam layer drying that works by removing water after the product is transformed into a stable foam, increasing its useful life and inhibiting microbial growth. This is also a way to enjoy the fruit during harvest periods, avoiding greater waste. Thus, the objective of this work was to obtain and evaluate the quality of the red jambo powder through drying in a foam layer using Emustab® as an emulsifying agent. The foam was characterized in terms of physical parameters (density, percentage of expansion and over run, stability) and physical-chemical (ATT content, pH and moisture percentage). The complete factorial design methodology of 23 + 3 central points was used to verify the influence of the independent variables: concentration of the emulsifier (3%, 4% and 5%); stirring time (3 min, 4 min and 5 min) and drying temperature (50 ° C, 60 ° C and 70 ° C) on the dependent variables (drying time and final moisture of the powder) and on the characteristics of the powder obtained (solubility, yield, moisture content, ash, carbohydrates, lipids, proteins, ATT, pH, SST, ascorbic acid and aw) through statistical analysis. With the results obtained, it was observed that the increase in the drying temperature resulted in a better stability of the foam and in the reduction of the drying time. All experiments showed a characteristic drying curve, with a period of increasing rate followed by a period of decreasing rate. The highest drying rates were observed in experiments that used drying temperatures of 70 ° C. The mathematical model with the best fit for the experimental data was the Modified Page model. The obtained powder has an average humidity of 12.14% and water activity between 0.167 to 0.283, which favors its conservation and commercialization within the standards required by the legislation, characterizing jambo, as a microbiologically stable powder. The powder produced in the 11 experiments, showed good solubility in water and the chemical characteristics (ashes, carbohydrates, proteins and lipids) and physical-chemical characteristics (ATT, pH, SST and ascorbic acid) are superior to those found for fresh pulp, indicating that the drying process in a foam layer favors the concentration of nutrients in the red apple by eliminating the moisture content. When comparing the powder obtained by drying in a foam layer with the powder obtained by lyophilization, we have products with similar characteristics, with emphasis on the lipid content that increased and the protein content that was reduced on the foam layer drying.