Abstract

D-Allulose is the C-3 epimer of D-fructose, and widely regarded as a promising substitute for sucrose. It’s an excellent low-calorie sweetener, with 70% sweetness of sucrose, 0.4 kcal/g dietary energy, and special physiological functions. It has been approved as GRAS by the U.S. Food and Drug Administration, and is allowed to be excluded from total and added sugar counts on the food labels. Therefore, D-allulose gradually attracts more public attention. Owing to scarcity in nature, the bioproduction of D-allulose by using ketose 3-epimerase (KEase) has become the research hotspot. Herein, we give a summary of the physicochemical properties, physiological function, applications, and the chemical and biochemical synthesis methods of D-allulose. In addition, the recent progress in the D-allulose bioproduction using KEases, and the possible solutions for existing challenges in the D-allulose industrial production are comprehensively discussed, focusing on the molecular modification, immobilization, food-grade expression, utilizing low-cost biomass as feedstock, overcoming thermodynamic limitation, as well as the downstream separation and purification. Finally, Prospects for further development are also proposed.

摘要

D-阿洛酮糖是 D-果糖的 C-3 差向异构体，被广泛认为是有前途的蔗糖替代品。是一种优良的低热量甜味剂，甜度为蔗糖的70%，膳食能量为0.4kcal/g，具有特殊的生理功能。它已被美国食品和药物管理局批准为 GRAS，并且可以不包含在食品标签上的总糖和添加糖含量中。因此，D-阿洛酮糖逐渐受到更多公众的关注。由于自然界中的稀缺性，利用酮糖3-差向异构酶（KEase）生物生产D-阿洛酮糖已成为研究热点。本文对D-阿洛酮糖的理化性质、生理功能、应用以及化学生化合成方法进行了综述。此外，还全面讨论了利用KEases生物生产D-阿洛酮糖的最新进展，以及针对D-阿洛酮糖工业生产中现有挑战的可能解决方案，重点关注分子修饰、固定化、食品级表达、利用低成本以生物质为原料，克服热力学限制，以及下游的分离和纯化。最后还提出了进一步发展的展望。