Impact of microwave heating on hemagglutinins, trypsin inhibitors and protein quality of selected legume seeds.

Selected legume seeds (dry and soaked) including faba beans, peas, chickpeas, soybeans, lentils and common beans containing 8 and 25% moisture, respectively, were subjected to microwave heating, and to a conventional cooking method to determine the heating effect on toxic compounds and protein quality. Trypsin inhibitors, hemagglutinins and available lysine were analyzed, and laboratory rats were used to determine digestibility and protein efficiency ratio (PER). Results indicated that microwaving destroyed trypsin inhibitors to a similar degree to that observed in beans cooked using the conventional method without affecting PER for raw seeds with low antinutrients content (faba beans, peas, chickpeas and lentils). Microwave-heated soaked soybeans had a higher amount of destroyed trypsin inhibitors, along with a higher PER, compared with microwave-heated dry soybeans. Microwave heating of common beans failed to destroy hemagglutinins and trypsin inhibitors, and consequently their digestibility and PER values were poor. Finally it was concluded that microwave heating constitutes an adequate method for destroying hemagglutinins and trypsin inhibitors without affecting protein quality of most legume seeds, except for common beans that despite of this process retained the antinutritional substances.

Diagnosis of lactose intolerance through the quantification of hydrogen in exhaled air.

Considerations are made on diarrhea secondary to intestinal malabsorption of carbohydrates and on the diagnostic means available in our environment, among which are the reactive strip, the clinitest tablet, tolerance curves and research of intestinal enzymes. The quantification of exhaled hydrogen is mentioned as a diagnostic method, used by several other authors, and a review of the literature on the subject is made. Considerations are made on a hydrogen quantification in the breath of patients with a transitory lactose intolerance. 16 patients were studied, 15 of whom showed an increase in the exhaled H2. 32 children with diarrhea, free from lactose intolerance, were studied. The method used did not show a significant increase in the exhaled hydrogen. 27 patients showed no H2 in their breath. In 4 there was elimination of H2 (false positives). 17 diarrhea-free children were studied. A significant difference was found when comparing the children with diarrhea and lactose intolerance to the other two groups who were free from lactose-intolerance. It is considered that this method can be useful in the diagnosis of intolerance to lactose and other sugars.

[Nutritive quality of ayocote beans (Phaseolus coccineous) supplemented with methionine at different cooking stages]. / Calidad nutritiva del ayocote (Phaseolus coccineous) suplementado con metionina en diferentes etapas de la cocción.

The purpose of the present study was to evaluate the nutritive quality of the Ayocote bean (Phaseolus coccineous) and to determine whether it could be increased by the addition of methionine. Methionine (0.6%) and salt (4%) were added at the beginning of cooking, 30 min before the beans were cooked or at the end when they were cooked, dried and ground. The beans were dried with or without broth. Proximate analysis, amino acids determination, available lysine, in vitro and in vivo digestibility as well as PER were determined in the bean flours. A second experiment was carried out using diets supplemented with increasing amounts of methionine (0.1-1%). The addition of this amino acid improved the chemical score, but methionine continued to be the first limiting amino acid. The beans dried with broth showed lower chemical score values than those dried without broth. The concentration of available lysine was lower in the beans dried with broth; the content of it in the beans was, however, still high. No significant differences were found in the PER's of the beans supplemented with different concentration of methionine. The addition of the amino acid can be effected at any step of cooking, since it was found that the thermic treatment did not reduce the utilization of the methionine added.

Trypsin inhibitors and hemagglutinins in certain edible leguminosae.

All raw legumes contain, in different proportion, several toxic substances that prevent consumption in their natural form. In this study the contents of the two main toxic products and their degree of destruction after thermic treatment similar to home cooking techniques were determined in 13 edible legumes. Proximate chemical analysis was made, and in vitro digestibility, contents of trypsin inhibitors and hemagglutinins in raw and cooked samples were studied. In the cooking treatment the legumes were boiled for two hours at boiling temperature under atmospheric pressure. Protein content in the samples was high, as in most legumes (20 per cent or more). Peas, lentils and broad beans had the lowest content of trypsin inhibitors and hemagglutinins. Cooking destroyed these substances, but did not improve in vitro digestibility, probably because of the reactions between their components when exposed to heat.