Use of cowpea (Vigna unguiculata) in mixtures with common beans (Phaseolus vulgaris) for the development of new food products

The objective of the study was to evaluate cowpeas (V. unguiculata) as a partial substitute of common beans (P. vulgaris) as a paste or as cooked dry flour. The degree of substitution would be that in which the flavor of cowpeas is not detected in the mixture with common beans. The study was developed utilizing the Black Peruchin variety of cowpea and the ICTA Ligero for common beans, the latter with 18.7% protein and cowpeas with of 24.4%. Other nutrients in the samples were similar. It was believed that the characteristic earth flavor of the cowpea was due to its content of polyphenolic compounds. To eliminate such compounds, the samples were soaked in water for various periods of time and cooked. Reduction was also achieved by dehulling. It was found that the polyphenolic levels obtained with 9 hrs. of soaking and 30 min. of cooking in water were equal to those measure with mechanical dehulling. Applying these process to cowpeas, two fried beans pastes were prepared with cowpeas (with and with out hulls) in a mixture of 70 common beans and 30 cowpeas. Likewise a precooked flour of the two legume grains in the same proportion was also tested. These samples were subjected to sensory trials using a triangular method, and by a descriptive profile. In these the following were evaluated: color, texture, salt level, and flavor, using a 10 point scale. The sensory evaluation of the two beans mixtures showed no significant differences with respect to common bean flavor. The protein content of the mixtures was high due to the high protein content of cowpeas. Even though the mixtures of common beans and cowpeas with and with out seed coat gave higher protein quality values as compared to common beans alone, the difference was not statistically significant.