Production and Bioactivity of Oligosaccharides in Plant Foods

Oligosaccharides are low-molecular-weight carbohydrates widely distributed in nature as plant storage carbohydrates. Fructan-type oligosaccharides (FTO) are widely present in vegetables and cereals while legumes are natural sources of α-galactooligosaccharides (α-GOS) among which raffinose family oligosaccharides (RFO) and galactosyl cyclitols are included. The production of oligosaccharides is of great interest since they are thought to have several interesting bioactivities and applications. Production of FTO and α-GOS is feasible by direct extraction from plant materials. Conventional solvent extraction has been commonly used for large-scale production. Recently, other technologies such as ultrasounds, microwaves, pressurized or supercritical fluids are being investigated to assist FTO and α-GOS extraction. In addition, new methods and techniques have been developed for purification of natural oligosaccharides. The body of scientific evidence supports a relationship between consumption of these natural oligosaccharides and changes in gastrointestinal microbiota composition and activity which have been linked to other beneficial physiological effects including enhanced mineral absorption, stimulation of the immune system, regulation of lipid metabolism, appetite suppression, body fat reduction, and attenuation of oxidative stress.