Process development for maltodextrins and glucose syrup from cassava

The objective of this study was to produce maltodextrins (MD) and glucose syrup (GS) throughout a smallscale process from the direct conversion of cassava roots collected in Burundi and previously detoxified. The detoxified cassava slices were blended with water at ratios of 1:1.0; 1:1.3; 1:1.6. Then, the cassava mash was undergone previously to gelatinization and then to liquefaction experiments aimed at obtaining MD with a Dextrose Equivalent (DE) value < 20. The doses of 0.013, 0.016, 0.019, 0.025, and 0.075 % (venzyme/wfresh mash) thermostable a-amylase (Liquezyme-X) were investigated to be added to cassava mash at pH 6.5 before and after 10 min - 90 °C step at atmospheric pressure (patm) or 143.27 kPa (110 °C) allowing the starch gelatinization. Then liquefaction times of 10, 15, 20, 30, 40, 45, 60, 90 and 120 min were tested. The saccharification step followed the liquefaction in order to obtain a GS with DE close to 99. The hydrolyzed cassava mash from liquefaction experiments was added at pH 5.4 and 60°C with 0.019 % (venzyme/wfresh mash) glucoamylase (Dextrozyme GA) and pullulanase (Dextrozyme GX) testing 1, 2, 4, 6, 18, 24, and 48 h incubation times. All experiments were done in duplicate and analysis of variance (ANOVA) with Tukey's test at p=0.05 was used to measure the effect of changing variables among treatments. Correlation Pearson's test were applied to measure the strength of the interactions between the variables. Results showed that the 10 min-143.27 kPa (on lab-scale) and the 12 min-145÷152 kPa (on small-scale) burst of starch granules in 1:1.6 cassava: water mash with 0.013 % (venzyme/wfresh mash) thermostable a- amylase at pH 6.5 followed by 15 min-90 °C liquefaction phase at patm allowed at obtaining MD with DE value < 20. In order to gain a GS having a DE value close to 99, a 4 h-60 °C saccharification phase at pH 5.4 with 0.019 % (venzyme/wfresh mash) glucoamylase and pullulanase should be carried out. Finally, highly significant correlations were found out between the water amount in the cassava mash, the concentration of the a-amylase enzyme, and the liquefaction time. This type of process had the advantage to be simple and practical, with reduced working times and enzyme doses, so to be popularizing especially in developing Countries. Further investigations are needed on some energy intensive operations, as like as pH adjustment, pressure increasing, and heating.