Evaluation of the effects of canning variables on the mineral composition of canned cowpeas (Vigna unguiculata l. Walp) using multi-response analysis.

This study aims to investigate the effects of canning variables (cooking time, storage time, volume of vinegar, salt and sugar) on the mineral composition of canned cowpea (Vigna unguiculata (L.) Walp) and which conditions provide optimised preservation of the mineral content of the grains. Different formulations of canned cowpeas were produced following two levels factorial experimental design using five variables. A set of 11 different formulations were evaluated using the desirability function with essential minerals (Ca, Cu, Fe, Mn, Mg, P and Zn) as the response. The optimal multi-response conditions for higher mineral retention were: 360 days of storage at 30 ± 5 °C (ST2), 30 ml of vinegar, 9.0 g of NaCl, 18 min of cooking time, and 9.0 g, 19.5 g or 30 g of sugar (the effect of the sugar content at the evaluated range was not significant at 95% confidence level).

Evaluation of the nutritional quality of cereal bars made with pulse flours using desirability functions.

The development of nutritious, low-cost snacks has become increasingly important due to consumer demand for healthier diets. In this study, sensory and physical-chemical parameters and mineral compositions (P, Ca, Na, K, Mg, Fe, Zn, Al, Cu, Mn, Ni and Ba) of cereal bars were evaluated. The bars were made with flours of Lablab purpureus L. Sweet (mangalo), Vigna unguiculata L. Walp (cowpea) or Cajanus cajan L. Huth (pigeon pea) and the desirability function was used to attain the best formulation for maximising the content of protein, fibre, ashes and essential elements. Sensory analysis revealed satisfactory acceptability. Acidity did not change significantly (p > 0.05), and water activity values ​​did not exceed 0.557 over 90 days, indicating stability. Principal component analysis revealed no significant differences when comparing the mineral content between the bars. The desirability function indicated that the cowpea-based bar had a higher nutritional quality, with a protein content of 4.91 ± 0.25 g 100 g-1, P content of 187.7 ± 3.6 mg 100 g-1, Mg content of 87.37 ± 1.19 mg 100 g-1 and Mn content of 2020 ± 130 µg 100 g-1, than the other bars. The overall sensory evaluation also yielded a high score for the cowpea-based bar (overall quality equal to 6.23 ± 1.10). Therefore, pulse flours could be potential nutritional ingredients for making snacks, and in particular, cereal bars containing them could be a viable product alternative for small rural cooperatives.