Title : Impact of Drought on the Physical and Cooking Properties of Six Common Bean Genotypes in Puerto Rico
Abstract:
Grain legumes, such as common beans, are a significant part of the global food system and a substantial source of protein and carbohydrates. In the diet of Puerto Ricans, common beans represent an essential component. However, several factors can limit their production on the island: competitive import prices, biotic and abiotic stresses such as drought. Drought has a direct influence in physical and cooking properties of common beans which affects consumer acceptance. The objective of this study was to analyze the effect of drought on physical and cooking properties of a subset of six out of thirteen common bean genotypes grown under a non-stressed (NS) and drought-stressed experimental plots (DS) in Puerto Rico. Selected seeds used in this experiment were collected and stored at freezing temperatures. For each genotype, dimensions, color, bulk density, and true density were determined. In addition, hydration capacity, swelling capacity, cooking time, and gruel solid loss procedures were carried out. Dimensions of five out of six studied genotypes were affected by drought conditions. Pinto beans had the greatest values of length (10.85 - 11.90 mm), thickness (6.35 - 7.02 mmm) and width (4.64 - 5.22 mm) regardless of treatment. Most of the color parameters observed for each of the six common beans genotypes were not significatively different between the NS and
DS treatments. Bulk and true density values were higher in black beans genotypes compared with navy and pinto beans. There was no significative effect of drought treatment on bulk and true density comparing the same genotype in the two studied conditions. Similarly, NS and DS treatments did not exhibit differences in porosity. However, one of the navy beans showed differences between DS treatment (38.56%) and NS treatment (35.90%) in their porosity values. High values of hydration capacity were observed in genotypes under NS treatments of black and pinto beans, ranged from 0.21 to 0.23 g/seed and from 0.28 to 0.33 g/seed, respectively. Swelling capacity was not significatively different for black and navy beans in regard of treatments. Nevertheless, pinto beans under NS treatment exhibited greater swelling capacity (0.28 – 0.32 mL/seed) than DS treated pinto beans (0.25 - 0.28 mL/seed). In terms of cooking times, black beans genotypes had the lowest times (29.61 - 9.50 min) whereas navy beans had the highest values (43.17 - 26.28 min) regardless the treatment. Although NS treatments had lower cooking times (40.61 - 26.00 min) than DS treatments (43.17 - 28.39 min), it is worth mentioning the cooking times of the navy beans exhibited shorter cooking times under the DS treatment (40.33 min) than NS treatment (43.00 min). Gruel solid loss ranged between 9.99 to 5.30 %, 8.63 to 5.80 %, 8.11 to 4.06 %, for black, pinto, and navy beans, respectively. Cooking and physical properties of grain legumes can be affected by drought; however, some genotypes develop attributes to overcome these effects and show acceptable quality in terms of color, dimensions, and cooking times..
