Investigation into Native Mango Starch Carboxymethylation

Abstract

The optimum reaction conditions for the preparation of carboxymethylated starch from native mango (Mangifera indica) starch were investigated. This was in a bid to utilizing the abundant mango waste seeds in the environment as alternative unconventional resource for both domestic and industrial applications. Organic slurry method was employed in the carboxymethylation process. While the effects of NaOH and SMCA concentrations, reaction time and temperature on Reaction Efficiency (RE) and Degree of Substitution (DS) of the products were studied. The DS obtained for the 18 carboxymethylated starches are CMS-1 (0.184), CMS-2 (0.156), CMS-3 (0.139), CMS-4 (0.258), CMS-5 (0.201), CMS-6 (0.197), CMS-7 (0.299), CMS-8 (0.258), CMS-9 (0.308), CMS-10 (0.164), CMS-11 (0.099), CMS-12 (0.143), CMS-13 (0.214), CMS-14 (0.058), CMS-15 (0.081), CMS-16 (0.258), CMS-17 (0.039), and CMS[1]18 (0.172). As expected, the results showed that the DS and RE were affected by all parameters investigated with CMS-9 and CMS-17 having the highest and lowest DS and RE respectively. It was concluded that the optimum reaction conditions for carboxymethylation of native mango starch are concentration of nNaOH/nAGU and nSMCA/nAGU (2M), and reaction time (2 h).