Resumo

BONILLA M., ROCÍO; HOYOS C., JOSÉ LUIS  e  VELASCO M., REINALDO. EFFECT OF CASSAVA STARCH OXIDATION OVER MECHANICAL AND THERMAL PROPERTIES OF BIODEGRADABLE FILMS. Rev.Bio.Agro [online]. 2013, vol.11, n.1, pp.208-217. ISSN 1692-3561.

This study evaluated the effect of different oxidation conditions by hypochlorite, on the content of carboxyl and carbonyl groups of cassava starch, finding that the concentration of oxidant had the highest effect on the formation of both groups functional. The pH had a highest effect on the content of carbonyl groups than on the content of carboxyl groups. Likewise, oxidized starch was obtained at three degrees of oxidation which exhibited lower viscosity, higher gel stability and lower retrogradation tendency when compared with native starch. Films were obtained and their mechanical and thermal properties were evaluated, finding that higher modification degree incremented stress while the strain exhibited no significant differences. Conversely, the greater modification degree, the films showed lower strain and the stress showed no significant differences. The thermal analysis showed a Tg, which is not present in native starch films, a higher Tm and a gradual decrease of ΔHm with oxidation degree increasing, which might suggest a greater miscibility and interaction between film components as well as greater stability.

Palavras-chave : Carboxyl groups; Carbonyl groups; Viscosity; Manihot esculenta Crantz.

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