Viability of sous vide, microwave and high pressure processing techniques on quality changes during shelf life of fresh cowpea puree.

An innovative cowpea puree containing 78.8% of fresh cowpea seeds was developed. Microwave treatment (8 kW/35 s), high hydrostatic pressure (550 MPa/10 min/23 ℃) or sous vide treatment (80 ℃, 3 min) were assayed as processing techniques. Blended fresh cowpea samples were used as control. Quality changes during 21 days at 5 ℃ were studied. Sous vide samples showed a relevant loss during storage of viscoelastic parameters, like elastic modulus (G') and viscous modulus (G″), which was also perceived in the sensory evaluation. On the contrary, high hydrostatic pressure and microwave treatments were able to preserve consistency, texture and taste. However, physicochemical properties, mainly colour, were greatly influenced by thermal treatments, although high hydrostatic pressure treatment preserved greenness. Total phenolic content and total antioxidant capacity were more affected by high hydrostatic pressure than by microwave treatments. In conclusion, microwave and high hydrostatic pressure processing treatments seem to be quite interesting techniques to develop legume-based products.