Effective approach for obtaining high-purity prebiotics using membrane separation technology

Abstract

With the increasing interest in functional products, prebiotics that selectively stimulate growth and activity of good bacteria in human gut, gained attention from both general and scientific community. The range of food products containing prebiotic oligosaccharides is rapidly expanding, causing their intensified production. Currently, there are a few recognized prebiotics, amongst which, fructo-oligosaccharides (FOS) proved to be particularly interesting owing to the confirmed positive effect on human wellbeing (restoring microbiota balance, improving immunity and lipid metabolism, enhancing vitamin production and calcium absorption) and exceptional physicochemical qualities. Namely, good taste quality, low sweetness, and low caloric value make them highly applicable supplement in food industry. Fructo-oligosaccharides are scarcely present in natural sources and nowadays are mainly produced by enzymatic conversion of sucrose and sucrose-rich substrates. Bearing in mind the complexity of synthesis process, resulting reaction mixture besides FOS (mixture of tri-, tetra- and pentasaccharides) contains significant portion of sucrose and monosaccharides. Within this study, efficient method for obtaining high-purity product upon sucrose conversion using fructosyltransferase (Pectinex® Ultra SP-L) was developed through detailed optimization of membrane separation processes. Under determined optimal conditions for nanofiltration (temperature of 35 °C, concentration of initial sugars of 3% and flow rate of 25 mL/min), undesired components (monosaccharides and partially sucrose) were removed from the initial mixture (58% FOS in total carbohydrates) and 1.48-fold increase the proportion of targeted bioactive components was achieved. Thus, product of high purity (86% FOS in total carbohydrates) was obtained with remarkable recovery yields of 90%. The prebiotic activity of the obtained product was confirmed in in vitro tests with several microbial cultures comprising representatives of beneficial (genera Lactobacillus and Saccharomyces) and pathogenic (Escherichia coli) gut microbiota. Having said that, it can be concluded that high-purity prebiotic product with great potential for application in different value-added food industry products was obtained.