Mixtures of corn or rice with dehulled soybeans (70:30) were extruded at three cone openings. Processing temperatures were inversely correlated with cone opening. As cone opening increased fat retention and nitrogen solubility index increased, while dispersibility, protein nutritive value and acceptability (as "atole") by school children decreased. The PER and NPR of the mixtures were significantly (P < 0.05) correlated with processing temperature (r = 0.90 for both) and sensory score (r = 0.83 and 0.82, respectively). No correlation was observed between protein nutritive value and residual antiphysiological factors of the products. After storage of mixtures for 12 wk at 4" and 25"C, fat acidity values were lower than 2%; those stored at 35°C showed nearly 10%. All samples were equally acceptable.
The purpose of this study was to determine the effect of bean polyphenolics on bean protein digestibility in humans. Steam pressure cooking decreased tannic acid in beans by: 38.2 (white), 23.9 (red), 38.5 (white:black mixture, 50:50), 20.5 (Ipala black) and 44.4% (Jalpatagua black). The reduction in catechin was: 57.5, 97.6, 83.0, 78.7 and 88.4%, respectively. The content of tannic acid in dried cooked beans was: 284.9 in white, 834.5 in red, 620.2 in the white:black mixture, 1,021 in Ipala black and 1,009 mg/100 g in the Jalpatagua black bean. These percentages correlate significantly with fecal nitrogen (r = 0.29, p less than 0.05). Catechin of the dried cooked beans was 7.5 in white, 27.4 in red, 25.4 in the white:black mixture (50:50), and 60.1 and 55.5 mg/100 g in each of the black cultivars, and correlated significantly with fecal nitrogen (r = 0.34, p less than 0.01), absorbed nitrogen (r = -0.37, p less than 0.01) and protein digestibility (r = -0.35, p less than 0.01). It was concluded that one of the factors that reduces bean protein digestibility is the polyphenlic compound.
A series of experiments were performed to study further the effect of supplementing corn with whole soybeans processed in a batch home process and in a continuous industrial operation on chemical composition, presence of antiphysiological substances and protein quality of tortillas. Variables studied with the conventional home cooking process included levels of whole soybeans from O-20%, cooking times at atmospheric pressure and 96°C from O-90 min at a constant corn-to-soybean ratio of 85:15 and lime concentration of 0, 1 and 2%. In the industrial process a 9O:lO mixture of corn to whole soybeans was used, and processing conditions were those normally employed for corn alone. Although addition of whole soybeans to corn increased total protein and fat content, both the PER and weight data suggest that the optimum amount of soybeans to add to maize falls between 8 and 12%. Levels of soybeans above 12%, did not significantly improve PER any further. Antiphysiological factors were inactivated after 30 min of cooking independent of lime concentration in the home process. These factors were also inactivated in the industrial process as measured chemically and by biological assays. The study demonstrated the feasibility of producing an enriched tortilla flour at the industrial scale, which besides containing a higher protein content and quality, also provides an increased amount of calories to the consumer.
publications on the subject, especially concerning those legume seeds more often consumed, such as soybeans and common beans. Of these factors, trypsin inhibitors (TI) and hemagglutinins (HA) have been considered as the main ones, although lately the importance of tannins and associated polyphenols has been recognized, since several authors have reported the ability of these components to inhibit the activity of a vast spectrum of enzymes, influencing the digestibility of the diets (Bressani and Elias,
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