Sheila Mara Sanches Lopes

Chemical characterization and prebiotic activity of fructo-oligosaccharides from Stevia rebaudiana (Bertoni) roots and in vitro adventitious root cultures.

Stevia rebaudiana (Bertoni) is widely studied because of its foliar steviol glycosides. Fructan-type polysaccharides were recently isolated from its roots. Fructans are reserve carbohydrates that have important positive health effects and technological applications in the food industry. The objective of the present study was to isolate and characterize fructo-oligosaccharides (FOSs) from S. rebaudiana roots and in vitro adventitious root cultures and evaluate the potential prebiotic effect of these molecules. The in vitro adventitious root cultures were obtained using a roller bottle system. Chemical analyses (gas chromatography-mass spectrometry, (1)H nuclear magnetic resonance, and off-line electrospray ionization-mass spectrometry) revealed similar chemical properties of FOSs that were obtained from the different sources. The potential prebiotic effects of FOSs that were isolated from S. rebaudiana roots enhanced the growth of both bifidobacteria and lactobacilli, with strains specificity in their fermentation ability.

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.

Spectrophotometry as a Tool for Dosage Sugars in Nectar of Crops Pollinated by Honeybees

The study of sugar from floral nectary is important for identification if a rise or decrease in quantity or nectar quality. The plant may secret a little bit of nectar, but with high sugar concentration, or unlike, secret more quantities, but with low sugar concentration. These differences in nectar may vary depend on pollinator visitation. However, the frequency of honeybees that visit flowers may contribute for rising nectar production like change the sugar proportion.