Abstract / Summary
ABSTRACT This study focused on the application and the optimization of the endogenous biotransformation of D-fructose in honey into D-allulose by D-allulose-3-epimerase (DAEase), aiming at producing a reduced-caloric functional honey. The enzymatic activity of DAEase was higher at 200 g/L and 700 g/L clover honey solutions compared to fructose solutions, respectively. A three-variable central composite rotatable design was used to optimize biotransformation parameters. Biotransformation was assessed by quantifying the amount of produced D-allulose and the bioconversion yield (%, w/w) of fructose. Coupled with the analysis of variance, the optimum reaction conditions were determined with critical parameters identified being honey concentration and reaction time. The optimized parameters were applied for the biotransformation of 12 honey samples from three different monofloral sources, namely clover ( Trifolium spp.), buckwheat ( Fagopyrum spp.), and blueberry. Results indicated a significantly lower bioconversion yield of D-allulose with an average of 9.55% (w/w) in buckwheat samples, when compared to clover and blueberry; however, a maximum bioconversion rate of 29.46% could be obtained in clover honeys. While the biotransformation had no significant impact on the viscosity and pH changes of all honey solutions, it reduced the post-reaction total color differences compared to the standard of blueberry honeys.