Likewise, starch has been previously used for the microencapsulation of vanillin extract ( Tari et al., 2002), liposoluble vitamins ( López-Hernández, 2010) and oleoresins ( dos Santos et al., 2005). The high amylose content is suitable for food coatings such as fruit, potato chips, etc., while the amylopectin content is applied as a thickening, stabilizing and adhesion agent. The food industry has used starch as a raw material due to its high availability, since they are found in diverse vegetable sources such as cereals, tubers, and roots ( Singh et al., 2004 Estrada-Girón et al., 2015), but also due to their high functionality when used as thickener and binder in the preparation of foods, including soups, sauces, baby foods, mayonnaise and bakery products ( Eliasson, 2004). These two polymers constitute most of the native starch granules and, in lower proportion, also contain lipids and minerals ( Copeland et al., 2009). Starch is a polymer formed by glucose units linked by alpha-D-(1,4) glucosidic bonds for the linear region corresponding to amylose, and alfa-D-(1,6) for branched region corresponding to amylopectin ( Thomas et al., 1999). The main structural component of rice grain is represented by the endosperm (93%), which is constituted by a majority fraction of starch (90%) ( Jualiano y Tuaño, 2019). An added value can be given to those grains by using them as raw material for starch extraction ( Colussi et al., 2015 Dias et al., 2010). During rice harvesting and processing, broken grains are obtained, that are not used as raw material for consumption. Two-thirds of the world population includes rice in their diet, and their annual demand increase to 480 million tons (USDA, 2015). Rice ( Oryza sativa L.) is one of the most consumed cereals in the world after corn, wheat and barley. Palabras clave: Almidón Modificado Almidón nativo Acetilación Extrusión Hidrólisis Los almidones evaluados presentan alto potencial para su uso como recubrimientos comestibles y como materiales de pared para microencapsulación. La presencia del grupo acetilo en la molécula de almidón se observó en las señales entre 1650-1744 cm-1, confirmando la esterificación. El ICR en AMH y AM aumentó con respecto al AN. La viscosidad de retrogradación presentó una disminución significativa (P<0.05) en AMH (0.013) y AM (5.613), asi mismo la dureza de los geles de almidón decreció (60 %) mientras que la adhesividad disminuyó únicamente en AM (66 %). La modificación mostró un incremento en IAA e ISA, obteniéndose el mayor valor de IAA en el AM (4.80) y de ISA en el AMH (32.06). El GS obtenido en ambos almidones se encontró dentro del rango permitido por la FDA (0.01-0.2) siendo seguro como ingrediente alimenticio. Keywords: Modified starch Native starch Acetylation Extrusion HydrolysisĪlmidón de arroz aislado (AN), fue sometido a modificación química y termomecánica con hidrólisis previa (AMH) y sin hidrólisis previa (AM), para ser caracterizado en grado de sustitución (GS), color, índice de absorción y solubilidad en agua (IAA e ISA), así como sus propiedades reológicas (viscosidad, textura), térmicas (Calorimetría diferencial de barrido - DSC) y estructurales (Infrarrojo- IR, rayos X-Rx e índice de cristalinidad relativa-ICR). ![]() The starches showed a high potential for its application as edible coatings and as wall material for microencapsulation. 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 ICR in MHS and MS increased with regard to the NS. 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 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 DS obtained in both starches was within the range allowed by the FDA for its safety use as food ingredient (0.01-0.2). 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).
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