Alcoholysis of Starch to Produce Alkyl Polyglycosides with Sub-Critical Isooctyl Alcohol

Synthesis of Butyl-β-D-Galactoside in the Ternary System: Acetone/1-Butanol/Aqueous Solution

The enzymatic synthesis of short-tailed alkyl glucosides is generally carried out in an aqueous-organic biphasic reaction medium with a rather low fatty alcohol concentration in the aqueous phase (where the synthesis occurs). Thus, hydrolytic reactions have a significant impact on the synthesis performance. Given this background, the use of acetone as cosolvent was studied for the synthesis of butyl-β-galactoside with Aspergillus oryzae β-galactosidase. The liquid-liquid equilibrium of the reaction mixture components (acetone/1-butanol/aqueous solution) was determined and the single- and two-phase regions were defined at 30, 40, and 50°C. It was observed that the liquid-liquid equilibrium of the ternary system acetone/1-butanol/water differs significantly from the one obtained using an aqueous solution (50 mM McIlvaine buffer pH 4.5; 5 g L^-1) instead of water. This is mainly because of the salting-out effect of the buffer; nevertheless, the presence of lactose also altered the equilibrium. Having this in mind, the effects of temperature (30 and 50°C) and reaction mixture composition were assessed. Three general conditions were evaluated: single-phase ternary system (30% acetone), two-phase ternary system (10% acetone) and two-phase binary system (0% acetone). Acetone had a deleterious effect on enzyme stability at 50°C, leading to low reaction yields. However, no enzyme deactivation was detected at 30°C. Moreover, a reaction yield of 0.98 mol mol^-1 was attained in the 30/50/20% (w/w) mixture of acetone/1-butanol/aqueous solution. This very high yield can be explained by the huge increase in the concentration of 1-butanol and the reduction of water activity. The synthesis was carried out using also the β-galactosidase immobilized in glyoxal-agarose and amino-glyoxal-agarose, and by aggregation and crosslinking. In the case of agarose-derived catalysts, two average particle diameters were assessed to evaluate the presence of internal mass transfer limitations. Best yield (0.88 mol mol^-1) was obtained with glyoxal-agarose derivatives and the particle size had non-effect on yield. The chemical structure of butyl-β-galactoside was determined by NMR and FT-IR.

Subcritical Methanolysis of Starch and Transglycosidation to Produce Dodecyl Polyglucosides

Biosurfactants based on carbohydrates are of special interest because of their production from renewable resources, nontoxicity, biocompatibility, and environmental friendliness. Dodecyl polyglucosides, a type of nonionic surfactant synthesized with methyl polyglucosides obtained from the eco-friendly subcritical methanolysis of renewable resource of starch, is no doubt good for ecosystem. With the subcritical methanolysis of starch, the methyl polyglucosides were obtained without any catalyst. Under the reaction condition of the weight ratio of methanol to starch of 7.5, temperature of 220 °C, and reaction time of 2 h, the yield of methyl polyglucosides was 85%. Dodecyl polyglucosides were synthesized by transglycosidation with methyl polyglucosides, and the green nonionic surfactant has excellent surface activity. The critical micelle concentration and hydrophilic lipophilic balance are 0.022 wt % and 12, respectively.