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The acylation of the rare sugar, D-allose (the C-3 epimer of D-glucose), with fatty acid vinyl esters was successfully carried out using Candida antarctica lipase in acetonitrile at 45 degrees C to give D-allose 6-alkanoates with high regioselectivity in good yields.

The diesterification of D-psicose (the C-3 epimer of D-fructose) with fatty acid vinyl esters of selected acyl chain lengths (C 8 , C 10 , and C 12 ) was successfully carried out using Candida antarctica lipase (Novozym 435) at 45°C for 24 h to give the 1,6-diacyl-D-psicofuranoses with a high regioselectivity in good yields (83-90%). These diesters of D-psicose have hydrophilic-lipophilic balance (HLB) values (6.5-8.2) similar to HLB values of monoglyceride compounds which constitute the largest single type of emulsifiers employed by the food industry. Ability of the D-psicose diesters to stabilize oil-in-water emulsions and the weight-averaged oil-droplet diameter in the emulsions was evaluated in this study. Emulsion stability of oil droplets stabilized by D-psicose dicaprylate (0.3%, w/v in oil phase) was comparable to D-fructose dicaprylate (0.2%, w/v). It was further confirmed that the D-psicose diesters exhibited an emulsification activity depending on the chain length of fatty acid; D-psicose dicaprate showed better emulsion stability than the other diesters.