Comprehensive Analysis of Allulose Production: A Review and Update

Abstract

Advancements in D-allulose production have seen significant strides in recent years, focusing on enzymatic conversion methods. Key developments include traditional immobilization techniques, the discovery of novel enzymes, directed evolution studies, and biosynthesis through metabolic pathway modification. Enzymatic conversion, particularly utilizing D-allulose 3-epimerase, remains fundamental for industrial-scale production. Innovative immobilization strategies, such as functionalized nano-beads and magnetic MOF nanoparticles, have significantly enhanced enzyme stability and reusability. Directed evolution has led to improved enzyme thermostability and catalytic efficiency, while synthetic biology methods, including phosphorylation-driven and thermodynamics-driven pathways, have optimized production processes. High-throughput screening methods have been crucial in identifying and refining enzyme variants for industrial applications. Collectively, these advancements not only enhance production efficiency and cost-effectiveness but also adhere to sustainable and economically viable manufacturing practices. The past five years have witnessed critical developments with significant potential impact on the commercial viability and global demand for allulose.

Keywords: allulose; directed evolution; immobilization.

Figure 1

Schematic representation of reaction, where D-fructose is converted to D-allulose in the presence of 3-Epimerase.

Figure 2

The conversion of D-fructose into D-allulose coupling with phosphorylation method.

Figure 3

Chemical structures of the sugar–borate complexes. (A) Fructose as β-d-fructopyranose cis-C-4,5 diol borate. (B) Psicose as α-d-furanopsicose cis-C-3,4 diol borate.