Repolho roxo em pó obtido em secador por aspersão e liofilizador.

Abstract

Red cabbage is mostly sold in its fresh form, which leads to losses due to leaf burning, wilting, discoloration, among other factors that cause quality losses. Because it is rich in chemical and mineral compounds, making it interesting, mainly, due to the presence of anthocyanins in its composition. This work aimed to obtain powdered red cabbage by two methods: spray drying and freeze drying, as well as to evaluate the physical-chemical, chemical and physical parameters in the products obtained. The leaves of the red cabbages were washed, sanitized, cut and crushed. Subsequently, the juice was refined, conditioned and stored. The formulations were made with red cabbage juice and 10, 15 and 20% maltodextrin and subjected to physical-chemical, chemical, texture profile analysis and dynamic viscosity. The formulated juices were also subjected to spray drying and lyophilization. In the latter, they were first frozen for later drying. The powders obtained were submitted to the analysis of water activity, water content, total soluble solids, pH, total titratable acidity, ash, SST/ATT ratio, minerals, luminosity (L*), red intensity (a*), intensity da azul (-b*), chroma (C*), tint angle, darkening index, anthocyanins, flavonoids, antioxidants, and phenolic compounds. The yield, hygroscopicity, solubility, wettability, apparent and compacted density were determined and from these, the Hausner Factor and Car index were calculated. The yield, hygroscopicity, solubility, wettability, apparent and compacted density were determined and from these, the Hausner Factor and Car index were calculated. Scanning electron microscopy and water adsorption isotherms of red cabbage powders were performed. According to the results obtained, it is concluded that the use of maltodextrin, provided an increase in the parameters of the texture profile and dynamic viscosity, which from an industrial point of view makes it difficult to flow and heat exchange during the process. However, the increase in temperature provided a reduction in dynamic viscosity, being favorable to facilitate the flow of the fluid, resulting in less energy expenditure, less adherence of the sample to the walls of the drying chamber, favoring the yield of the final product. The increase in the concentration of maltodextrin and drying temperature implies a tendency to reduce water activity, water content, total titratable acidity, anthocyanins, reflected in the reduction of red and blue tones, degradation of bioactive compounds, hygroscopicity, solubility, wettability apparent and compacted density. The ash content and mineral profile are negatively and positively influenced by the increase in maltodextrin concentration and temperature, respectively. The increase in these variables generates an increase in total soluble solids, yield, more luminous samples, irregular particles, larger and with less aspect of shrinkage. The isotherms of red cabbage powders at different temperatures and concentrations of maltodextrin obtained in a spray and lyophilization dryer were best represented by the Peleg model, showing type II behavior.