Effect of soaking prior to cooking on the levels of phytate and tannin of the common bean (Phaseolus vulgaris, L.) and the protein value.

The effect of soaking in domestic processing, on the nutritive value of the common bean (Phaseolus vulgaris, L.) cv IAC-Carioca, was studied. Five treatments were carried out with experimental diets, and offered to male, recently weaned Wistar rats. The protein sources were, respectively, control diet (casein) (CC), casein plus the soluble solids found in the soaking water (CSS), freeze dried bean cooked without soaking (BNS), freeze dried bean cooked with the non-absorbed soaking water (BSW), freeze dried bean cooked without the non-absorbed soaking water (BSNW). and an aproteic diet (AP) for corrective purposes. The anti-nutritional factors (phytates and tannins), were determined in the differently processed beans and in the soaking water. The following values for the reduction of phytates were obtained: BNS (20.9%), BSNW (60.8%) and BSW (53.0%), and the tannins were reduced by: BNS (86.6%), BSNW (88.7%) and BSW (89.0%). No significant differences were observed between the various treatments using the common bean as protein source, with respect to the net protein ratio (NPR). With respect to the digestibility corrected by non-protein diet, values varying between 94.1% and 94.6% for casein, and between 57.5% and 61.4% for the common bean, were observed, the treatment BNS being more digestible. It was concluded that soaking did not interfere with the NPR of the experimental diets containing the common bean as protein source, nor did it reduce the tannin content. However soaking was capable of reducing the phytate levels in the common bean. On the other hand, soaking was unable to increase the protein digestibility of the common bean, since the treatment BNS showed the highest value for digestibility.

Soaking the common bean in a domestic preparation reduced the contents of raffinose-type oligosaccharides but did not interfere with nutritive value.

The objective of this study was to verify the effect of soaking on the factors causing flatulence in the common bean (Phaseolus vulgaris, L.) cv. IAC-Carioca during domestic preparation. A biological assay using recently weaned (21 days) male Wistar rats provided the Food Conversion Efficiency (FCE) and the Net Protein Ratio (NPR). Five treatments were carried out with isocaloric (350.9 +/- 37.9 kcal/100 g) and isoprotein (12.0 +/- 0.5%) experimental diets, with the following protein sources: beans cooked without soaking (BNS), beans soaked and cooked with the soaking water (BSWW), beans soaked and cooked without the residual soaking water (BSNW), control diet (casein) (CC), casein plus the total soluble solids found in the soaking water (CSS) for comparative purposes, and an aproteic diet (AP) for corrective purposes, all diets offered ad libitum. The contents of raffinose-type oligosaccharides were determined in the different domestic preparations of the beans. Significant reductions were observed in the contents of the oligosaccharides raffinose (25.0%), stachyose (24.8%), and verbascose (41.7%), and in the contents of total sugars (80.6%), reducing sugars (58.2%), nonreducing sugars (90.3%), and starch (26.8%) when soaking took place before cooking and elimination of the soaking water not absorbed by the beans (BSNW) was used. No significant difference (p > 0.05) was observed between the values for FCE and NPR of the control diet (casein) and control diet plus soaking water soluble solids. Neither was any significant difference between the values for the different bean treatments found, though the values for FCE and NPR were lower than those obtained for casein treatments. Thus it was verified that although the domestic preparation of the common bean significantly reduced the contents of raffinose-type oligosaccharides, total reducing and nonreducing sugars and starch, it did not interfere with its nutritive value.

O processamento doméstico do feijão-comum ocasionou uma redução nos fatores antinutricionais fitatos e taninos, no teor de amido e em fatores de flatulência rafinose, estaquiose e verbascose / The domestic processing of the common bean resulted in a reduction in the phytates and tannins antinutritional factors, in the starch content and in the raffinose, stachiose and verbascose flatulence factors

The objective of this study was to evaluate the effect of the soaking step and the domestic processing of the common bean, on the chemical composition, the levels of phytate, tannin, starch and flatulence factors by utilizing the follows treatments: raw bean (FC), freeze-dried cooked unsoaked bean (FCSM), freeze-dried cooked bean without the non-absorbed soaking water (FCSAM), freeze-dried cooked bean with the non-absorbed soaking water (FCCAM) and the soaking water (AM). The beans were soaking for a period for 16 hours in the proportion 3:1 (water:beans) at room temperature. The effect of the phytates and tannins on the net protein efficiency ratio (NPR) and protein digestibility using male Wistar rats were studied. A decrease in the phytate content of the beans (85) with use of soaking was observed. In the case of the tannin content, only the cooking of the beans promoted high decomposition (84). In the (FCSAM) treatment a decrease in the raffinose (25.0), stachiose (24.8), verbascose (41.7) and starch (26.8) contents was observed. Diets containing casein (control), casein plus the soluble solids obtain from the soaking water showed no significant difference (p > 0.05) for the NPR, as well as for the different bean treatments, although these showing lower values. The treatment (FCSM) showed the higher digestibility (74.3 +/- 5.8) of the bean treatments, the casein diets showing 94.6 +/- 0.9. The reduction of the phytates, tannin, starch contents and flatulence factors in the common bean was most effective when the soaking water not absorbed was discarded (FCSAM).