Estudos quÃmico e bioquÃmico do yacon (Smallanthus sonchifolius) âin naturaâ e processado e influÃncia do seu consumo sobre nÃveis glicÃmicos e lipÃdeos fecais de ratos / Chemical and biochemical studies of in natura and processed yacon (Smallanthus sonchifolius) and influence of its consumption on glucemic levels and fecal lipids of rats

Juciane de Abreu Ribeiro

Research on foods which can aid in the prevention and treatment of pathologies, mainly the non-transmissible chronic diseases, have been being more and more frequent. Seeking to increase the knowledge on yacon, this work was aimed to study that root and evaluate the influence of yacon pulp flour in the possible reduction of post-prandial glucemia and increase in fecal lipid content in experimental animals. For yacon and its flours, four replicates were done for the analyses of the centesimal composition, following the methods proposed by AOAC (1990), mineral content, determination of food fiber, pH, SST, ATT, anti-nutritional and toxic factors. In addition to evaluating polyphenoloxidase and peroxidase activity (PFO) (PER) for both the in natura yacon casca and pulp with four replicates. Phenolic acids (chlorogenic, caffeic and ferulic) were identified and quantified by HPLC and UV-vis detector for in natura pulp and casca and respective flours. For evaluation of the effect of yacon pulp flour on post-prandial glucemia, fecal lipids, ponderal development, diet intake and food efficacy coefficient, 24 albino, male, Wistar rats, weighing initially 200-250g (n= 6/group), were treated for 17 days with a diet containing yacon pulp flour, following the AIN-93M standards, causing detriment to the starch. The trial was conducted with the control groups, 5%, 10% and 15% of yacon pulp flour. The analysis of fasting glucemia was performed in the animals of the different groups after 12 hour-fasting and so remained till 15 hours of fasting. After that period, 2g of the particular diets were given to each group for evaluation of post-prandial glucemia in 15 minute-intervals to complete 2 hours. The blood puncture was done on the animalsÂ tail, utilizing glicosÃmetros apparatuses and Accu-ChekÂ strips. The statistical analyses were performed by the regression method, the values of p<0.05, being with 0.1% BHT in methanol and 10% acetic acid, a clean-up was performed and afterwards, a filtering in a 0.45Âm membrane. The analyses were done in a HPLC system with spectrophotometric detector in the UV/Vis region with a wavelength set at 330nm. The samples were injected in a column (250 x 4.6 mm, 5 μm) connected to an analytic pre-column and the mobile phase utilized was made up of the solvents: 100% methanol (HPLC degree) solvent A â and solution of 2% aqueous acetic acid- solvent B and was employed in a gradient-type system. The flow applied was constant at 1.1 mL. min-1 and the volume of injection both of the standards and of the samples were of 20 μL. The quantification of each of the phenolic acids was done by utilizing analytic curves which were determine by plotting the peak areas of each of the compounds versus its concentration utilized. The analyses were in triplicate. Both the yacon pulp and pulp flour presented higher percents of moisture and carbohydrates in relation to casca and casca flour. On the other hand, numerically higher concentrations of lipids, proteins, fibers and ashes for casca and casca flour as compared with yacon pulp and pulp flour. Yacon and derived products represent excellent sources of fibers and considerable nutritional value. The presence of phenolic acids such as chlorogenic, caffeic and ferulic was identified, the average retention times being of 18.3; 19.5 and 27.6 minutes, respectively. The amounts found of chlorogenic acid were of 39,0; 294,0; 9,0 and 31,0 mg kg-1 of integral matter in PY, FPY, CY and FCY, respectively. However, caffeic acid presented in integral matter, the contents of 27,0mg kg-1 in PY; 417,0 mg kg-1 in FPY; 12,0 mg kg-1 in CY and 56,0 mg kg-1 in FCY. Ferulic acid was found at the concentrations of 3,0; 30,0; 2,0 and 5,0 mg kg-1 of integral matter in PY, FPY, CY and FCY, respectively. Both FPY and PY presented themselves as the best sources of phenolic acids and the dehydration process enhanced the concentration of phenolic acids. The different treatments with FPY did not influence in CMD, GMD and CEA of the animals. Reduction of the IG of the diets with addition of FPY could be observed, the effect being equivalent to all the proportions of this foodstuff. It follows that FPY reduces post-prandial glucemia, standing for a tool in preventing and treatment of diabetes, obesity and other particular situations as physical exercises. In addition, the increment of FPY in growing amounts in the diets caused a proportional arraste of lipids for the animalsÂ feces.

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