Secagem em camada de espuma do espinafre (Tetragonia tetragonoídes L.)

Abstract

Spinach is a vegetable with high nutritional value, as it is rich in fiber, vitamins and minerals. It contains antioxidant compounds such as vitamin C, phenolic compounds and carotenoids, which help maintain health and prevent chronic diseases. Due to its high perishability, it requires a preservation method, such as drying, in order to reduce water content, maintain product stability and extend its shelf life. The objective of this study was to obtain spinach leaf powder by drying in a foam layer. The foam obtained from spinach leaves added with the emulsifier Portogel was characterized according to the following parameters: density, expansion percentage, air incorporation, stability, total titratable acidity, pH and moisture. Drying was performed according to a 23 + 3 central points factorial experimental design, in which the independent variables were: emulsifier concentration (2, 3 and 4%), stirring time (6, 7 and 8 min) and temperature (50, 60 and 70 °C) and the dependent variables (drying time and moisture content). The drying kinetics data were subjected to mathematical adjustment using the Newton, Page, modified Page, Henderson and Pabis, Logarithmic and Midilli models. The powders obtained from spinach leaves were characterized according to the following parameters: pH; total soluble solids (TSS); total titratable acidity (TTA); water activity (Aw); moisture; ash; proteins; lipids; carbohydrates; color and total phenolic compounds (TPC). From the results obtained for drying, it was found that temperature was the variable that presented a statistically significant influence on the 95% confidence interval on the final drying time and that the modified Page model was the one that presented the best fit to the experimental data. And for the powders obtained, it was found that: they presented a slightly acidic character, with an increase in the acidity content after drying; high content of soluble solids ranging from 36 to 44 ºBrix; water activity (˂ 0.6) and moisture in accordance with the recommendations of the legislation (≤ 15%), favoring conservation and storage; significant content of phenolic compounds (1457.81 to 2056.88 mg EAG 100 g-1 ); green coloration, varying to darker tones when increasing the drying temperature from 50 to 70 ºC; the contents of proteins, lipids, ash and carbohydrates were concentrated after drying. Thus, it was concluded that the spinach leaf powder obtained by foam layer shows promise for application in new formulations in the food and pharmaceutical industries. In addition, foam layer drying is a fast and viable process for obtaining spinach leaf powder.