Organocatalytic esterification of polysaccharides for food applications: A review

The esterification of carbohydrate polymers for food applications has been extensively investigated and reviewed. Despite this, the ability of esterified carbohydrate polymers as dietary fiber, as well as bio-based food packaging material makes this research area still of great interest. However, many of the reagents used during esterification lead to moderate to severe environmental pollution. The objective of this review manuscript was to provide an overview of the reaction mechanisms of organocatalytic esterification of carbohydrate polymers destined for food applications. Organocatalytically esterified polysaccharides (OEPs) have generally been synthesized via green catalyst-assisted esterification reactions, with the main objective of grafting short-chain fatty acids (SCFAs), simple organic acids and small hydrophobic moieties onto the backbone of carbohydrate polymers. These SCFA-grafted OEPs, including SFCA-grafted starch, escape digestion and can efficiently deliver SCFAs in the lower gut. SCFA-grafted OEPs can also influence colonic bacteria and derived catabolites in a manner that provides cardiometabolic benefits. OEPs can also be used for the development of food packaging with improved hydrophobicity and thermal stability. Remarkably, their degree of substitution (DS) underlies their improved functionality as dietary compounds and/or food contact materials, with DS values between 0.01 and 0.2 when OEPs are designed for human consumption. It should be noted that the DS of the OEPs is limited by the steric hindrances related to the structure of the native carbohydrate polymers and the grafted functional group, as well as the reaction conditions.