Characterization of powder from the permeate of yacon extract by ultrafiltration and dehydrated by spray drying

ABSTRACT Yacon root is a functional food which contains antioxidants and prebiotics compounds. This study aimed to evaluate the physical, chemical and prebiotic characteristics of a yacon extract powder obtained by ultrafiltration (UF) with membranes of 10 and 30 kDa and encapsulation of the resulting permeate by spray drying. Drying air temperatures of 140 and 160 ºC and concentrations of gum arabic of 10 and 15% were tested. The samples had solubility values greater than 90% while the hygroscopicity decreased with increasing gum concentration and drying temperature. Electron microscopy showed a strong tendency to agglomeration of smaller particles around the larger ones, mainly at a temperature of 140 ºC. Regarding color, the parameter L* showed that drying at 160 ºC produced darker samples and the parameters a* and b* indicated that all samples were greenish yellow. The concentration of inulin decreased during drying, whereas the levels of glucose and fructose increased due to the thermolysis reaction, which led to degradation of inulin chains at drying temperature. The permeates and retentates from the UF membranes had prebiotic activity, while only the encapsulated product from UF-30 membrane, metabolized by Lactobacillus acidophilus LA-5(r), presented activity scores without significant difference to that of glucose