Two-step biosynthesis of D-allulose via a multienzyme cascade for the bioconversion of fruit juices

Article abstract of DOI:10.1016/j.foodchem.2021.129746

D-Allulose, a low-calorie rare sugar with potential as sucrose substitute for diabetics, can be produced using D-allulose 3-epimerase (DAE). Here, we characterized a putative thermostable DAE from Pirellula sp. SH-Sr6A (PsDAE), with a half-life of 6 h at 60 °C. Bioconversion of 500 g/L D-fructose using immobilized PsDAE on epoxy support yielded 152.7 g/L D-allulose, which maintained 80% of the initial activity after 11 reuse cycles. A multienzyme cascade system was developed to convert sucrose to D-allulose comprising sucrose invertase, D-glucose isomerase and PsDAE. Fruit juices were treated using this system to convert the high-calorie sugars, such as sucrose, D-glucose, and D-fructose, into D-allulose. The content of D-allulose among total monosaccharides in the treated fruit juice remained between 16 and 19% during 15 reaction cycles. This study provides an efficient strategy for the development of functional fruit juices containing D-allulose for diabetics and other special consumer categories.