Atividade antioxidante, qualidade proteica e potencial funcional de genótipos de sorgo disponíveis à alimentação humana

• Autor(a) principal: Moraes, érica Aguiar
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2755
• topic: Sorgo; Atividade antioxidante; Compostos fenólicos; Qualidade proteica; Sorghum; Antioxidant activity; Phenolic compounds; Protein quality; CNPQ::CIENCIAS DA SAUDE::NUTRICAO

The increase in chronic diseases related to malnutrition demands the exploitation of alternative sources in order to develop healthy eating habits. In this context, sorghum is an alternative of consumption to conventional cereals due to its high concentration of phenolic compounds, such as phenolic acids, anthocyanins and condensed tannins, besides its dietary fiber content. However, enabling the consumption of cereals by humans demands the exposure of these cereals to some kind of thermal processing, which may result in changes to the bioavailability of nutrients and bioactive compounds. The aim of this study was to evaluate the antioxidant activity, the protein quality and functional potential of sorghum genotypes exposed to different kinds of thermal processing and for this evaluation, three experiments were performed. In the first one, the antioxidant activity and the concentration of total phenolics, condensed tannins and phytate were evaluated in seven sorghum genotypes. These analyses were carried out in flour (RF) and popcorn (SP) from raw sorghum grains and in flour from grains subjected to heat treatment in oven (HTF) (105ºC/30min.). Heat treatment in oven increased total phenolic content. The antioxidant activity and concentration of tannin and phytate were preserved. On the other hand, popped sorghum reduced antioxidant activity and the tannin content, compared to the raw sorghum flour. In the second experiment, the in vivo protein quality of flours from both raw sorghum grains (RF) and heat-treated sorghum grains (HTF) were evaluated in the BRS 305, BRS 309 and BRS 310 genotypes. These were selected due to the high antioxidant activity and the difference in the pericarp pigmentation shown in the first experiment. No difference was found for FER among the experimental groups (p&#8805; 0.05). Heat-treated flour from BRS 309 and BRS 310 genotypes had higher PER and NPR values, however, they did not differ from the values found in the raw grain flour of BRS 310 genotype (p<0.05). Heat treatment effect was observed in the BRS 309 genotype. The heat treatment had no effect on true digestibility (TD) between RF and HTF of the three genotypes (p&#8805; 0.05). Lysine was the first limiting amino acid of the three sorghum genotypes. The HTF BRS 305 showed the lowest protein digestibility-corrected amino acid score value (p<0.05). The heat treatment improved the protein quality of genotype BRS 309; however, there was no difference for the other genotypes. In the third experiment, the study evaluated the effect of adding flour of sorghum genotypes to high-fat diets upon the oxidative stress, response to inflammation and intestinal morphology in male adults Wistar rats. The animals were fed AIN-93M diet, high-fat diet control (DHC) and high-fat diet added with sorghum BRS 305 (DHS 305), BRS 309 (DHS 309) and BRS 310 (DHS 310) for four weeks. The antioxidant activity and total anthocyanins did not differ among sorghum genotypes (p&#8805; 0.05). However, total phenolics, condensed tannins, luteolinidin and apigeninidin were higher in BRS 305 (p<0.05). The food consumption in the AIN-93M group was higher than in the DHC, DHS 305 and DHS 310 groups (p<0.05). The energy consumption, final weight, body weight gain, epididymal fat, and food efficiency ratio were similar between the experimental groups, as well as the concentrations of glucose, fructosamine, total cholesterol and HDL cholesterol, triglycerides, liver enzymes and superoxide dismutase (p&#8805; 0.05). The DHS 310 group showed lower levels of malondialdehyde and expression of TNF-&#945; (p<0.05). The intestinal villi height in the DHC, DHS 305, DHS 309 and DHS 310 groups did not differ (p&#8805; 0.05). We can infer that the BRS 310 genotype has a favorable chemical and nutritional composition for human consumption due to the preservation of high antioxidant activity with the exposure to heat treatment in an oven, the best biological indices of protein quality, the maintenance of intestinal morphology, besides the reduction in lowgrade inflammation and oxidative stress.