A new natural source for obtainment of inulin and fructo-oligosaccharides from industrial waste of Stevia rebaudiana Bertoni.

Fructan-type inulin and fructo-oligosaccharides (FOS) are reserve polysaccharides that offer an interesting combination of nutritional and technological properties for food industry. Stevia rebaudiana is used commercially in the sweetener industry due to the high content of steviol glycosides in its leaves. With the proposal of using industrial waste, the objective of the present study was to isolate, characterize and evaluate the prebiotic activity of inulin and FOS from S. rebaudiana stems. The chemical characterization of the samples by GC-MS, NMR and off-line ESI-MS showed that it was possible to obtain inulin molecules from the S. rebaudiana stems with a degree of polymerization (DP) of 12, and FOS with a DP<6. The in vitro prebiotic assay of these molecules indicates a strain specificity in fermentation capacity of fructans as substrate. FOS molecules with a low DP are preferably fermented by beneficial microbiota than inulin molecules with higher DP.

Biochemical composition of symplastic sap from sugarcane genetically modified to overproduce proline.

Global interest in sugarcane has increased significantly in recent years because of its economic impact on sustainable energy production. The purpose of the present study was to evaluate changes in the concentrations of total sugars, amino acids, free proline, and total proteins by colorimetric analyses and nuclear magnetic resonance (NMR) to perform a metabolic profiling of a water-soluble fraction of symplastic sap in response to the constitutive expression of a mutant Δ1-pyrroline-5-carboxylate synthetase (P5CS) gene from Vigna aconitifolia. However, there was not a significant increase in the free proline content in the sap of transgenic plants compared to the non-transformed control plants. The most noticeable difference between the two genotypes was an almost two-fold increase in the accumulation of sucrose in the stem internodes of P5CS transgenic sugarcane plants. The results presented in this work showed that transgenic sugarcane plants with increased levels of free proline accumulates high soluble sugar content and, therefore, may represent a novel genotype for improving sugarcane cultivars.