Abstract

GRAJEDA-NIETO, Nancy Paola et al. Use of hydrolysis prior to the chemical and thermomechanical modification of rice starch: alternative to traditional modification treatments. Biotecnia [online]. 2021, vol.23, n.1, pp.151-160.  Epub June 18, 2021. ISSN 1665-1456.  https://doi.org/10.18633/biotecnia.v23i1.1296.

Isolated rice starch (NS), was subjected to chemical and thermomechanical modification with (MHS) and without (MS) previous hydrolysis for the evaluation of the main starch properties such as degree of substitution (DS), color, water absorption and solubility index (WAI, WSI), viscosity, texture, thermal properties (differential scanning calorimetry DSC) and structural properties (infrared-IR, Xray-Rx analysis, and relative crystallinity index-ICR). The DS obtained in both starches was within the range allowed by the FDA for its safety use as food ingredient (0.01-0.2). The modification showed an increase in WAI and WSI values, being WAI value higher in MS (4.80) and WSI value higher in MHS (32.06). The viscosity of retrogradation showed a significant decrease (P<0.05) in MHS (0.013) and MS (5.613), however, the hardness of starch gels decreased (60 %) while the adhesiveness decreased only in MS (66 %). The ICR in MHS and MS increased with regard to the NS. The presence of the acetyl group in the starch molecule was observed in the signals between 1650 to 1744 cm-1 confirming the esterification. The starches showed a high potential for its application as edible coatings and as wall material for microencapsulation.

Keywords : Modified starch; Native starch; Acetylation; Extrusion; Hydrolysis.