MODIFICATION OF IRISH POTATO STARCH USING MONOCHLOROACETIC ACID

ABSTRACT

This study investigates the carboxyl methylation modification of Irish potato starch using monochloroacetic acid, with a specific emphasis on the influence of varying starch to monochloroacetic acid ratios on the degree of substitution (DS) and cold water solubility. Notably, the effect of the ratio on DS was most pronounced in Sample 2, featuring a ratio of 1.5:1 (starch to monochloroacetic acid), which yielded the highest DS and percentage of carboxylmethyl substitution (%CMS). This finding suggests that a ratio of 1.5:1 could be an optimal condition for achieving a substantial degree of substitution. It's essential to note that the ratio of reactants plays a significant role in determining the degree of substitution, as it directly impacts the availability of reactive sites and the resulting substitution level. Moreover, an intriguing observation was made concerning cold water solubility. As the amount of monochloroacetic acid increased from Sample 1 to Sample 4, the cold water solubility of the modified starch decreased. Sample 1, with the least amount of monochloroacetic acid, exhibited the highest cold water solubility, while Sample 4, with the highest amount of monochloroacetic acid, demonstrated the lowest solubility. This inverse relationship between the amount of monochloroacetic acid and cold water solubility highlights the delicate balance required to optimize both the DS and solubility of carboxylmethyl starch. Understanding this interplay is crucial for tailoring the modification process effectively to achieve the desired DS while maintaining suitable solubility, a vital factor for various industrial applications, ranging from instant food products to pharmaceuticals.