CONICET | Buscador de Institutos y Recursos Humanos

Fructo-oligosaccharides (FOS) are well recognized prebiotics, that is, non-digestible food components that beneficially affect the host health by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon [1]. Their beneficial properties include the modulation of colonic microflora, improvement of the gastrointestinal physiology and immune functions, bioavailability of minerals, metabolism of lipids, control of diabetes, reduction of uremia and prevention of colonic carcinogenesis [2].From a chemical point of view, FOS are composed of fructose units linked by (2?_1)-£]-glycosidic bonds and a single D-glucosyl unit at the non-reducing end of the chain. In most cases, FOS are mixtures of oligosaccharides with degree of polymerization (DP) from 3 to 6. They can be obtained by transfructosylation reactions using sucrose as substrate. Considering that the composition of FOS determines their prebiotic effect on human health, and this composition is in turn determined by the conditions of synthesis, the goal of this work was twofold: from one side, to obtain FOS enriched in DP3 and DP4, those with the highest prebiotic index and economic impact. From the other side, to define a model based on multivariate analysis to determine the composition of FOS directly from the FTIR spectra.Enzymatic reactions were carried out at a constant temperature of 30¢XC using Viscozyme L as biocatalyst. The progress of synthesis was followed by taking samples at regular intervals with further analysis by HPLC (reference method) and FTIR.The FTIR spectra were registered in the 4000-500 cm-1 range. For each eluate five spectra were registered by co-adding 64 scans with 4 cm-1 spectral resolution. Spectra corresponding to FOS of DP within 2-5 were used as standards.Principal component analysis (PCA) was performed on the spectra and allowed determining the spectral differences among oligosaccharides, occurring in the 1200-800 cm-1 region. On this basis, a Partial least square (PLS) model was calibrated to determine the percentual composition of each fraction obtained along the synthesis. To calibrate the model a group of 34 FTIR spectra covering the whole concentrations, including spectra obtained from independent experiments and repetitions, were used. The model was validated with an independent set of data. The mean of predicted values fitted nicely the composition of FOS obtained by HPLC, thus supporting the use of the PLS model to monitor transfructosylation reactions.Considering the health importnce of FOS, the possibility of monitoring their composition in situ and in real time, directly from the spectra, represents a useful tool to obtain reliable information with strong impact on health and economy.