Nutritional and anti-nutritional components of four cowpea varieties under thermal treatments: Principal component analysis

In the Northeast of Argentina, cowpeas are frequently produced by small- and medium-sized farmers for either personal consumption or trade. The objective of this work was to study, using a principal component analysis (PCA), the effect of thermal and non-thermal treatments on the nutritional and anti-nutritional properties of the four different varieties of Vigna unguiculata.Anti-nutrients contents allowed treatment differentiation for each variety because they contributed mainly in the PC1 axis construction (PCA). In contrast, nutrient (proteins and carbohydrates) contribution to treatment differentiation was not significant. Colorado variety presented the highest mineral in vitro availability, with the exception of iron. Thermal treatment increased the protein digestibility of all flours. The typical thermograms of native flours presented a two overlapping endotherm with denaturing temperatures (Td) of 83-84 °C and 91-93 °C respectively and a total enthalpy (ΔH) 7-9 J/g. Heat treatments produced a shift of Td (67-73 °C) with increasing treatment time.Cowpea seeds varieties, especially Colorado and Cuarenton, because of their nutritional and antinutritional components under thermal treatments, could be used as an alternative low cost protein source for food formulas.

► Thermal treatment decreased significantly the anti-nutrient content of all varieties analyzed. ► Autoclaving required a short treatment time than cooking for reaching similar anti-nutrient contents. ► Anti-nutrients allowed treatment differentiation for each variety, because they made greatest contribution to PC1 creation. ► Thermal treatment (cooking and autoclaving) increased the protein digestibility of flours.