Improvement of IMO production and prebiotic properties using optimal substrate and transglucosylation period

Abstract

This study focused on the determination of a suitable concentration of maltose and maltodextrin in saccharified rice solution for transglucosylation to reduce the IMO production time and maintain prebiotic properties. Maltose and maltodextrin reported as main substrates for transglucosidase enzyme were tested for a promising rate of IMO synthesis. Maltose utilization by transglucosidase enzyme was higher than that found in maltodextrin in the production of isomaltose, isomaltotriose, isomaltotetraose, isopanose, and isomaltohexaose. Hence, the liquefaction and saccharification of rice flour were optimized to produce high maltose solution. The liquefaction of rice flour at 95 °C with KLEISTASE T10S enzyme concentration of 0.035; 0.055 and 0.075%v/w, and rice flour of 20, 25, and 30%w/v were investigated for maximum hydrolysis. The liquefied solution was further treated with Biozyme LC enzyme concentrations (0.05, 0.015, and 0.20%w/v) at 45 or 60 °C. The result of maximum hydrolysis percentage was found as 87%w/w from the liquefying rice flour of 20%w/v for 40 min with 0.075%v/w Transglucosidase L “Amano” enzyme concentration. Subsequent saccharification with 0.2%v/w enzyme concentration at 60 °C for 30 min yielded highest maltose of 149.1 g/L; maltodextrin, 31.4 g/L, and glucose, 5.3 g/L. Tranglucosylation of the high maltose solution was monitored within 24 h at 6 h intervals. The maximum IMO was at 6 h and declined at a longer transglucosylation period. The trends of the prebiotic index and prebiotic activity scores were parallel with IMO concentration. In conclusion, the IMO could be synthesized from a low-cost resource of maltose in approximately 6 h at 65% yield.