Lactulose: properties, techno-functional food applications, and food grade delivery system

Background: Every year, high volumes of whey are producing by dairy industries, which require significant capital investments to discard this highly reactive by-product and to reduce its adverse impacts on the environment. Protein recovery and also whey lactose transformation to biologically active and high added value compounds such as lactulose, are the suggested solutions to reduce these issues. Lactulose is a prebiotic sugar with versatile applications in food and pharmaceutical industries. Scope and approach: This review mainly discusses current approaches of lactulose synthesis, its properties, applications in food and pharmaceutical sections, interactions with lipids and proteins, and its potential use as a food grade delivery system. Key findings and conclusions: The disaccharide lactulose is a synthetic and non-digestible sugar, which can be synthesized from lactose by glucose to fructose rearranging methods. Its β-glycosidic bond cannot be hydrolyzed by enzymes of upper part of digestional tract. As a potent prebiotic disaccharide, lactulose induces the growth of health-enhancing probiotics such as Lactobacillus and Bifidobacterium strains in concomitant with pathogen-growth suppression. Lactulose is applied in many food products as a bifidogenic agent and functional prebiotic additive for regulating intestinal functions. In pharmaceutical sciences, it can also be used as an effective therapeutic compound for treating some disorders like hepatic encephalopathy and chronic constipation and also as a food grade colon-targeted delivery system (CODES).