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Viscoelasticity of Cowpea Starch Gels

¹Graduate School of Biotechnology, Korea University, Sungbuk-Ku, Seoul 136-701, Korea. ²R&D Center, Pulmuone Co. Ltd., Seoul 120-110, Korea. ³Corresponding author. E-mail: limst@kuccnx.korea.ac.kr Phone: 02-3290-3435. Fax: 02-927-5201.

The mechanical behavior of cowpea starch gels (10%, w/v) at small and large deformations were investigated in comparison with acorn, corn, and potato starches in storage at 4°C for seven days. The rapid viscograms of starch paste (7%, w/v) revealed that cowpea starch had a larger setback (1,135 cP) than other starches (465–830 cP), although peak viscosity (1,723 cP) and pasting temperature (76°C) were between those of corn and potato starches. Texture profile analysis of cowpea starch gel showed exceptionally higher values for hardness, gumminess, chewiness and initial modulus than other starch gels. Cowpea starch gel also exhibited higher G′ and smaller tan δ compared with other starch gels, regardless of the storage time. A creep test revealed that the cowpea starch gel could remain highly resistant to stress, showing the least deformation among the tested starch gels during storage up to seven days. The overall results disclosed that cowpea starch was capable of forming exceptionally strong and elastic gels with good storage stability.