EFFECT OF THERMAL PROCESSING ON CHEMICAL COMPOSITIONS, BIOACTIVE COMPOUNDS, AND ANTIOXIDANT ACTIVITIES OF COWPEA CULTIVARS

ABSTRACT This study aimed to determine the effect of cooking on the centesimal compositions, the content of bioactive compounds, and antioxidant activities in beans of the cowpea cultivars. The beans were cooked without soaking (1:5 w/v) in a pressure cooker for 780 seconds. Statistical analysis was performed using Student’s t-test to determine the difference between means of raw and cooked beans. One-way ANOVA: post-hoc Tukey’s test was applied at 5% to compare the data of the cultivars. Significant difference (p 0.05) was noted between the moisture contents of samples, with values ranging from 10.69 to 11.37% in the raw beans and 63.32 to 75.43% in the cooked ones. Only BRS Marataoã showed a slight reduction (1.24%) in the energy value. The total polyphenol content in cooked beans decreased on discarding the broth. BRS Marataoã showed the highest levels of total polyphenols and flavonoids in raw beans, cooked beans, and broth. The raw beans of the cultivar BRS Itaim had greater content of condensed tannins and total anthocyanins. The raw beans, cooked beans, and broth showed statistically significant differences between their antioxidant activities, and the best results were found in the samples not subjected to thermal processing, particularly in BRS Marataoã. In conclusion, cooking influenced the concentration of bioactive compounds and antioxidant activities of the beans. Therefore, it is recommended that cooked cowpea beans should be consumed with the cooking broth for optimization of antioxidants. RESUMO Este trabalho objetivou verificar o efeito da cocção na composição centesimal, no conteúdo de compostos bioativos e na atividade antioxidante em grãos de cultivares de feijão-caupi. Estes foram cozidos sem maceração (1:5 p/v) em panela de pressão por 780 segundos. Na análise estatística utilizou-se o teste t de Student para verificar diferença entre a média dos grãos crus e cozidos. Por meio do método de one-way ANOVA: post-hoc, aplicou-se o teste de médias de Tukey ao nível de 5% para as demais variáveis. Em relação à composição centesimal, houve diferença significativa (p