Secagem da folha da amoreira negra (Morus nigra L.) pelo método de camada de espuma (Foam mat drying)

Abstract

Morus nigra L., popularly known as black mulberry, it is a plant with medicinal properties, whose parts, among them their leaves, objects of study for various types of diseases such as diabetes, for colic and climacteric symptoms, and others. However, because the leaf is in natura, its humidity is quite high, which is not desirable for being a favorable environment for the proliferation of microorganisms. Foam drying is a way to make this storage possible and still maintain its preserved properties. Therefore, the objective of this work was to obtain the black mulberry leaf powder by drying in a foam layer using Portogel® as a foaming agent. Preliminary tests were carried out for the foam such as stability, density, expandability, and over run. The factorial design methodology of 23 + 3 central points was used, totaling 11 experiments, having as independent variables, the concentration of foamy (3%, 5% and 7%), stirring time (3 min, 5 min and 7 min), and drying temperature (50 ° C, 60 ° C and 70 ° C) and their influence, on variables dependent on final drying time and final humidity was evaluated. With data obtained in the kinetics it was possible to obtain curves and drying rates, in addition to mathematical adjustments, where it was possible to observe that the models that best fit were those of Page and Modified Page. Analyzes of the powders obtained were performed as a theoretical yield of approximately 8%, a water activity that had a value below 0.320, an ash content of 12.90%, a solubility in water of 57.39%, a content of lipids of 12.85%, a slightly acidic pH ranging from 6.1 to 6.9, a total soluble solids content of 38 ° Brix, a titratable total acidity content from 0.6 to 1.2 g citric acid / 100g, a protein content of 21.75% and carbohydrates of 60.50%, a moisture content of 4.90 (bs), an ascorbic acid content in the range of 0.77 to 1.2 g of ascorbic acid / 100g, chlorophyll a of 200,43 ± 4,92, chlorophyll b of 74,77 ± 2,12 and total chlorophyll of 283,19 ± 9,87. With the results obtained it was possible to see that the temperature variable was the one that most influenced the final drying time and through the parameters used the foam layer drying method proved to be a viable process for this work, and the best experiment was the 7 (3%, 7 min, 70 °C), that in addition to using the lowest concentration of foamy, it also presented excellent results, such as shorter drying time, aw in the range, where there is no proliferation of microorganisms, and satisfactory results in the analysis of powder such as , b and total, water solubility, protein content and ° Brix.