Application of soluble fibres in the osmotic dehydration of pineapples and reuse of effluent in a beverage fermented by water kefir

Abstract

Osmotic dehydration (OD) consists of removing water from a medium against the concentration gradient. This process is usually conducted at mild temperatures to reduce nutritional and sensorial losses. The aim of this study was to evaluate the OD of pineapples using sucrose, fructooligosaccharides (FOS) and inulin as dehydrating agents and to reuse the effluent solutions for the production of a beverage fermented by water kefir grains. The OD of pineapple was performed by mixture factorial design with independent variables: sucrose (20–40 g/100 g), FOS (20–40 g/100 g) and inulin (0–20 g/100 g) concentrations. The results of the OD indicated that the effect of the concentration of FOS on water loss (WL) was greater than those of the concentrations of sucrose and inulin. In addition, in the drying stage, the fruits that underwent OD presented a reduction in time of drying (td) of 63.4% in relation to fresh fruit. The fermentations using the OD effluent were conducted without stirring for 24 h at 25 °C and the kefir culture was capable of satisfactorily fermenting the residual osmotic solutions in order to produce a potential symbiotic beverage.