Physicochemical characteristics of bean cultivars (Phaseolus vulgaris L.), and biological effects of soluble fiber fraction

Raw seeds of sixteen common bean (Phaseolus vulgaris L.) cultivars were evaluated along two consecutive harvests (2001/2002 and 2002/2003) concerning their physicochemical characteristics, as well as the effect of cooking and storage conditions on starch and dietary fiber contents. Serum lipids and blood glucose levels were also evaluated in normolipidemic-normoglycemic rats witch were fed diets containing bean cultivars with different soluble fiber/total fiber ratios (SF/TF): Pérola diet (0.11), Diamante Negro diet (0.19) and Iraí diet (0.26); control group was fed a standard diet (with insoluble fiber). Except for dry matter, moisture, and total dietary fiber, cultivars kept their chemical characteristics between harvests. Regarding similarity among macronutrient levels (crude protein-CP, total dietary fiber, insoluble dietary fiber, soluble dietary fiber-SF, digestible starch-DS, and resistant starch-RS) seeds from harvests 2001/2002 and 2002/2003 were categorized into four different groups; the same was done for micronutrients (Fe, Zn, Mn, Cu, Ca, Mg, and P), and four groups were also identified. Guateian 6662 and Rio Tibagi were considered the cultivars with the best nutritional profile (highest levels of CP, SF, DS, Fe, and Zn). Storage under refrigerated or freezing conditions did not change fiber content of cooked beans, but decreased their DS content and increased RS content, mainly in seeds with low RS levels before cooking. Concerning biological response, rats fed bean diets experienced lower values for serum cholesterol (P<0.05) and lower glycemic indexes (P<0.05). It was also observed a similar weight gain among groups, however animals fed bean based diets showed lower fat retention (P<0.05). The effects of bean diets on experimental groups were more remarkable in animals fed Iraí diet (SF/TF: 0.26).Foram analisadas as características físico-químicas de sementes cruas de dezesseis cultivares de feijão comum (Phaseolus vulgaris L.), ao longo de duas safras consecutivas (2001/2002 e 2002/2003), bem como os teores de amido e fibra alimentar nas sementes após cozimento e estocagem. Avaliaram-se, também, os lipídeos séricos e a glicose sanguínea de ratos normolipidêmicos e normoglicêmicos, alimentados com dietas contendo cultivares de feijão com diferentes relações fibra solúvel/fibra total (FS/FT): dieta Pérola (0,11), dieta Diamante Negro (0,19) e dieta Iraí (0,26); o grupo controle recebeu dieta padrão (com fibra insolúvel). Exceto pelos teores de matéria seca, umidade e fibra alimentar total, as cultivares estudadas mantiveram suas características físico-químicas constantes ao longo das safras. Conforme a similaridade nos teores de macronutrientes (proteína bruta-PB, fibra alimentar total, fibra alimentar insolúvel, fibra alimentar solúvel-FS, amido disponível-AD e amido resistente-AR) as sementes das safras 2001/2002 e 2002/2003 foram categorizadas em quatro grupos distintos; da mesma forma, em relação aos micronutrientes (Fe, Zn, Mn, Cu, Ca, Mg e P), quatro grupos puderam ser identificados. As cultivares Guateian 6662 e Rio Tibagi apresentaram o melhor perfil nutricional (maiores teores de PB, FS, AD, Fe e Zn). A armazenagem sob refrigeração e o congelamento não determinaram alterações nos teores de fibra dos grãos cozidos, mas redução do AD e aumento do AR, principalmente naqueles com AR mais baixo antes do cozimento. Em relação à resposta biológica, os ratos alimentados com dietas contendo feijão apresentaram valores para colesterol sérico e índice glicêmico menores que os do grupo controle (p<0,05). Foi observado, também, que apesar do ganho de peso dos animais ter sido semelhante entre os grupos, os ratos alimentados com as dietas contendo feijão apresentaram menor retenção de gordura corporal (p