Effect of dual modification of sonication and γ-irradiation on physicochemical and functional properties of lentil (Lens culinaris L.) starch.

Starch isolated from lentil was subjected to two treatments namely sonication and, a dual treatment of sonication and irradiation at a dose of 5kGy. Lentil yielded 26.12±1.56g starch/100g of lentil. Chemical composition of native starch revealed 7.83±0.28% moisture, 0.23±0.30% protein, 0.35±0.05% fat and 0.10±0.00% ash. The results revealed that pasting properties of lentil starch were not affected upon sonication. However, these decreased significantly (p≤0.05) upon dual treatments. Amylose content of native starch was 31.16±1.80g/100g which showed a decrease upon sonication and dual treatments. Sonication and dual treatments (sonication and irradiation) decreased hunter 'L' value while 'a' and 'b' values showed an increase. Syneresis decreased more or less insignificantly upon sonication. However, a significant decrease in syneresis was observed after 120h storage following dual treatments. Sonication did not decrease the functional properties significantly while as dual treatment induced a significant decrease in functional properties. FT-IR analysis revealed a decrease in the intensities of OH, CH and OC stretches and CH2 bending upon sonication and dual treatments.

Physicochemical properties of native and γ-irradiated wild arrowhead (Sagittaria sagittifolia L.) tuber starch.

Starch isolated from wild arrowhead tuber was treated by γ-irradiation at 0, 5, 10 and 15kGy doses. Arrowhead tubers yielded 40.33% starch and its chemical composition revealed moisture, protein, ash and fat were 8.34±0.09%, 0.26±0.04%, 0.58±0.02% and 0%, respectively. Physicochemical, morphological and pasting properties of native and irradiated tuber starches were investigated. The results showed that peak, trough, final, and setback viscosities were significantly (p≤0.05) reduced, whereas the breakdown viscosity increased following irradiation. Physicochemical properties differed significantly and showed strong dose dependent relationship. Solubility, water absorption capacity and transmittance increased, whereas swelling power, bulk density and syneresis decreased upon increase in irradiation of starch. Correlation studies showed that irradiation dose was positively correlated with water absorption capacity and solubility index while it correlated negatively with pasting properties, swelling index, syneresis, and freeze thaw stability.