Effect of different home-cooking methods on the bioaccessibility of zinc and iron in conventionally bred cowpea (Vigna unguiculata L. Walp) consumed in Brazil.

BACKGROUND: The cowpea (Vigna unguiculata L. Wap.) is an excellent source of iron and zinc. However, iron from plant sources is poorly absorbed compared with iron from animal sources. OBJECTIVES: The objective of this study was to evaluate iron and zinc bioaccessibility in cowpea cultivars after processing. METHODS: Zinc and iron bioaccessibilities in cowpea samples were determined based on an in vitro method involving simulated gastrointestinal digestion with suitable modifications. RESULTS: When water-soaked beans were cooked in a regular pan, the highest percentage of bioaccessible iron obtained was 8.92%, whereas when they were cooked in a pressure cooker without previous soaking, the highest percentage was 44.33%. Also, the percentage of bioaccessible zinc was 52.78% when they were cooked in a regular pan without prior soaking. Higher percentages of bioaccessible iron were found when cooking was done in a pressure cooker compared with regular pan cooking. In all cultivars, cooking of cowpea beans in both pressure cooker and in a regular pan yielded higher percentages of bioaccessible zinc compared with availability of bioaccessible iron. CONCLUSIONS: Iron bioaccessibility values suggest that cooking in a regular pan did not have a good effect on iron availability, since the percentage of bioaccessible iron was lower than that of zinc. The determination of iron and zinc bioaccessibility makes it possible to find out the actual percentage of absorption of such minerals and allows the development of efficient strategies for low-income groups to access foods with high levels of these micronutrients.

Comparative analysis of nutritional compositions of transgenic RNAi-mediated virus-resistant bean (event EMB-PV051-1) with its non-transgenic counterpart.

Golden mosaic is among the most economically important diseases that severely reduce bean production in Latin America. In 2011, a transgenic bean event named Embrapa 5.1 (EMB-PV051-1), resistant to bean golden mosaic virus, was approved for commercial release in Brazil. The aim of this study was to measure and evaluate the nutritional components of the beans, as well as the anti-nutrient levels in the primary transgenic line and its derived near-isogenic lines after crosses and backcrosses with two commercial cultivars. Nutritional assessment of transgenic crops used for human consumption is an important aspect of safety evaluations. Results demonstrated that the transgenic bean event, cultivated under field conditions, was substantially equivalent to that of the non-transgenic bean plants. In addition, the amounts of the nutritional components are within the range of values observed for several bean commercial varieties grown across a range of environments and seasons.

Effects of cooking methods on the iron and zinc contents in cowpea (Vigna unguiculata) to combat nutritional deficiencies in Brazil.

BACKGROUND: Because iron deficiency anemia is prevalent in developing countries, determining the levels of iron and zinc in beans, the second most consumed staple food in Brazil, is essential, especially for the low-income people who experience a deficiency of these minerals in their diet. OBJECTIVES: This study aimed to evaluate the effect of cooking methods by measuring the iron and zinc contents in cowpea cultivars before and after soaking to determine the retention of these minerals. METHODS: The samples were cooked in both regular pans and pressure cookers with and without previous soaking. Mineral analyses were carried out by Spectrometry of Inductively Coupled Plasma (ICP). RESULTS: The results showed high contents of iron and zinc in raw samples as well as in cooked ones, with the use of regular pan resulting in greater percentage of iron retention and the use of pressure cooker ensuring higher retention of zinc. CONCLUSIONS: The best retention of iron was found in the BRS Aracê cultivar prepared in a regular pan with previous soaking. This cultivar may be indicated for cultivation and human consumption. The best retention of zinc was found for the BRS Tumucumaque cultivar prepared in a pressure cooker without previous soaking.

Retention of total carotenoid and ß-carotene in yellow sweet cassava (Manihot esculenta Crantz) after domestic cooking.

BACKGROUND: Over the last decade, considerable efforts have been made to identify cassava cultivars to improve the vitamin A nutritional status of undernourished populations, especially in northeast Brazil, where cassava is one of the principal and essentially only nutritional source. OBJECTIVES: The aim of this study was to evaluate the total carotenoid, ß-carotene, and its all-E-, 9-, and 13-Z-ß-carotene isomers content in seven yellow sweet cassava roots and their retention after three boiling cooking methods. DESIGN: The total carotenoid, ß-carotene, and its all-E-, 9-, and 13-Z-ß-carotene isomers in yellow sweet cassava samples were determined by ultraviolet/visible spectrometry and high-performance liquid chromatography, respectively, before and after applying the cooking methods. All analyses were performed in triplicate. RESULTS: The total carotenoid in raw roots varied from 2.64 to 14.15 µg/g and total ß-carotene from 1.99 to 10.32 µg/g. The ß-carotene predominated in all the roots. The Híbrido 2003 14 08 cultivar presented the highest ß-carotene content after cooking methods 1 and 3. The 1153 - Klainasik cultivar presented the highest 9-Z-ß-carotene content after cooking by method 3. The highest total carotenoid retention was observed in cultivar 1456 - Vermelhinha and that of ß-carotene for the Híbrido 2003 14 11 cultivar, both after cooking method 1. Evaluating the real retention percentage (RR%) in sweet yellow cassava after home cooking methods showed differences that can be attributed to the total initial carotenoid contents. However, no cooking method uniformly provided a higher total carotenoid or ß-carotene retention in all the cultivars. CONCLUSION: Differences were found in the cooking methods among the samples regarding total carotenoid or ß-carotene retention, suggesting that the different behaviors of the cultivars need to be further analyzed. However, high percentages of total carotenoid or ß-carotene retention were observed and can minimize vitamin A deficiency in low-income populations.

Iron and zinc retention in common beans (Phaseolus vulgaris L.) after home cooking.

BACKGROUND: According to the World Health Organization (WHO), iron, iodine, and Vitamin A deficiencies are the most common forms of malnutrition, leading to severe public health consequences. The importance of iron and zinc in human nutrition and the number of children found to be deficient in these nutrients make further studies on retention in cooked grains and cooked bean broth important. OBJECTIVES: This work aimed to evaluate iron and zinc retention in six common bean (Phaseolus vulgaris L.) cultivars under the following conditions: raw beans, regular pot cooking, pressure cooking, with and without previous water soaking, and broth. DESIGN: Determination of iron and zinc content in the raw, cooked bean grains and broth samples was carried out by Inductively Coupled Plasma (ICP) Optical Emission Spectrometry (Spectro Analytical Instrument - Spectroflame P). All experiments and analyses were carried out in triplicate. RESULTS: Overall, regardless of the cooking method, with or without previous water soaking, the highest zinc concentration was found in the cooked bean grains. However, pressure cooking and previous water soaking diminished iron retention in the cooked grains, while increasing it in the bean broth. CONCLUSION: The common bean was confirmed to be an excellent source of iron and zinc for human consumption, and it was suggested that beans should be consumed in a combined form, i.e. grain with bean broth.