Effect of gamma irradiation on the physicochemical and structural properties of plant seed gums

The objective of the study was to evaluate the effect of irradiation (0-5 kGy) on the physicochemical properties of two seed gums (guar and locust bean gum). The Hunter color parameters changed upon irradiation, namely L value decreased, whereas a and b values, i.e. redness and yellowness, increased. Irradiation reduced the final viscosity of gums at neutral and acidic pH. Increase in irradiation dose (0-5 kGy) increased the water absorption in the range of 11.75-14.61 g/g and 20.04-23.99 g/g in guar gum and locust bean gum, respectively. Rheological study of the gums revealed their gel behaviour with higher values of G' than G. G' in native guar gum was observed to increase in the range of 880.39-1332.29 Pa while G increased in the range of 194.21-239.77 Pa as the test frequency was raised from 14.6-100 s(-1). In native locust bean gum, the G' and G varied in the range of 476.50-1230.50 Pa and 300.65-380.30 Pa, respectively, under the applied frequency sweep. FT-IR revealed the presence of -CH, -COOH and -C=0 groups in the guar as well as locust bean gum, in addition to the uronic acid and pyranose rings. The absorption of the functional groups declined upon irradiation. (C) 2017 Elsevier B.V. All rights reserved.