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Oxidized maize starch: Characterization and its effect on the biodegradable films part II. infrared spectroscopy and solubility

In addition, the oxidized maize starch film experienced a lower solubility than the film of native starch. It can be explained that the oxidation process, more or less, changed the interaction between amylose molecules as well as the strong intramolecular bonds due to the appearance of carbonyl, carboxyl and thus reducing the water absorbance of oxidized starch films. | Vietnam Journal of Science and Technology 55 (4) (2017) 395-402 DOI: 10.15625/2525-2518/55/4/7919 OXIDIZED MAIZE STARCH: CHARACTERIZATION AND ITS EFFECT ON THE BIODEGRADABLE FILMS PART II. INFRARED SPECTROSCOPY AND SOLUBILITY Dao Phi Hung1, *, Mac Van Phuc1, Nguyen Anh Hiep1, Trinh Van Thanh1, Nguyen Thien Vuong1, Truong Thi Nam1, Do Dang Xuan2 1 Institute for Tropical Technology, VAST, 18 Hoang Quoc Viet, Cau Giay, Hanoi 2 Tran Quoc Tuan University, Co Dong ward, Son Tay town, Hanoi * Email: dphung@itt.vast.vn Received: 22 March 2016; Accepted for publication: 2 July 2017 ABSTRACT The oxidization of starch was carried out by reacting starch with a specific amount of hypochlorite, i.e. 0.5; 1 and 2 g active chlorine/100 g starch, under controlled temperature and pH. The effects of hypochlorite level on functional groups and film’s solubility of maize starch were investigated. For IR spectrum of oxidized starch, there was a little difference of spectra shape while intensity of some characteristic vibrations showed changes in comparison with native starch IR spectra. To specify, the vibration at 1760 cm-1 of oxidized starch corresponding to carbonyl group indicated an increase of intensity while the intensity of absorptions at 3424 cm-1 (hydroxyl group) and 1640 cm-1 (intra-molecular hydrogen bond) illustrating on oxidized starch IR spectrum experienced a slight decrease in comparison with native starch IR spectrum. The solubility of native starch and oxidized indicated that there was, up to a point, a little scission chain in oxidation process if modifying maize starch by sodium hypochlorite at low concentration (≤ 2 % active chlorine). In addition, the oxidized maize starch film experienced a lower solubility than the film of native starch. It can be explained that the oxidation process, more or less, changed the interaction between amylose molecules as well as the strong intramolecular bonds due to the appearance of carbonyl, carboxyl and thus reducing the .