Nutritional and cooking quality of grains from different commercial classes of cowpea (Vigna unguiculata L. Walp.)

Abstract

Cowpea (Vigna unguiculata L. Walp.) is a crop of great socioeconomic importance in the Northeast region of Brazil, being a generator of employment and income for thousands of people and a source of proteins, minerals, diet fibers and bioactive compounds, which help in the prevention of various diseases. This work aimed to evaluate the nutritional and cooking quality of grains from different commercial classes of cowpea. Raw and cooked grains from 10 cowpea genotypes were evaluated. The proximate composition and total energy value (TEV) were determined, according to AOAC; iron (Fe), zinc (Zn) and selenium (Se) contents, by ICP-OES; phytic acid content by method 986.11 AOAC; and cooking quality, using an electric pressure cooker and Matsson cooker. The nutritional and cooking quality index (IQNC) was estimated, considering proteins, Fe, Zn, Se, and cooking quality as positive characteristics and the phytic acid content as a negative characteristic. Genotype means were grouped using the Scott-Knott test (p<0.05) and raw and cooked grains using Student's t test (p<0.05). There were significant differences between genotypes for all traits except for proteins and carbohydrates in raw grains. Cooking increased protein content in genotypes IT97KD-1042 and BRS Olhonegro, and Zn, in all genotypes, and reduced phytic acid by 10.43 to 30.64%. Cooking quality was greater than 52% for all genotypes. The cultivars BRS Tumucumaque, BRS Imponente and BRS Olhonegro, both belonging to the white commercial class, highlighted with the highest IQNC. These cultivars can be used in programs aimed at combating malnutrition and confirm the nutritional value of cowpea and the quality contribution it can provide when included in a balanced diet.