Emulsion stabilization mechanism of combination of esterified maltodextrin and Tween 80 in oil-in-water emulsions

Food Science and Biotechnology - Esterified maltodextrins (EMs) were prepared using enzyme-catalyzed reaction of maltodextrin (DE of 16 and 9) and palmitic acid. The emulsion stabilization...     

Bovine serum albumin-sugar conjugates through the maillard reaction: effects on interfacial behavior and emulsifying ability

Bovine serum albumin (BSA) was employed as a model protein emulsifier to conjugate with aldohexose (D-glucose (Glc) or D-allose (All)) and sugar fatty acid ester (6-O-octanoyl-D-glucose (GlcC8)) through the Maillard reaction. It was found during the reaction that rate of decrease of free amino groups in BSA was almost the same for the BSA-sugar mixtures whereas browning and protein aggregation developed in the following order: Glc < All < GlcC8. It was thought that the rate of degradation of the Amadori compound could have been influenced by the OH-group stereochemistry at the C3 position of aldohexose, while denaturation of BSA by GlcC8 enhanced the browning and protein aggregation. To understand the emulsifying ability of the BSA-sugar conjugates, hexadecane-water interfacial tension and the oil droplet size of emulsions prepared by homogenizing hexadecane and aqueous solution of the conjugates were examined. BSA-GlcC8 showed greater improvement in interfacial and emulsifying activity than did BSA-Glc and -All. However, no improvement in emulsion stability was observed for any of the BSA-sugar conjugates, suggesting the weakness of the film formed at the oil droplet interface.     

Lipase-Catalyzed Synthesis of d-Psicose Fatty Acid Diesters and their Emulsification Activities

The diesterification of d-psicose (the C-3 epimer of d-fructose) with fatty acid vinyl esters of selected acyl chain lengths (C₈, C₁₀, and C₁₂) 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.     

Oxidation and Colloidal Stability of Oil-in-Water Emulsion as Affected by Pigmented Rice Hull Extracts

Extracts from the hull of pigmented rice were prepared using a mixture of methanol–water (1:1, 2:1, and 3:1, v/v) for different extraction times (0–180 min). Total phenolic content (TPC) of the extracts increased with increasing concentration of methanol and extraction time (P < 0.05). A positive correlation between TPC and antioxidant activities, i.e., DPPH and ABTS radical scavenging activities and reducing power, was observed. The extracts prepared using methanol–water at the ratio of 3:1 for 180 min at 50 °C, referred as rice hull phenolic extract (RHPE), showed the highest TPC and free radical scavenging abilities and reducing power (P < 0.05). When the effects of RHPE on physicochemical stability of the emulsions stabilized by different emulsifiers, i.e., Tween 20 and bovine serum albumin (BSA), were examined, the collapse of emulsion was retarded when RHPE was applied in BSA‐based emulsions, whereas a negative effect was noticeable in Tween 20‐based counterpart. Lower oxidative degree was found for BSA stabilized emulsions, compared to Tween 20 containing system. RHPE (1–3 %) markedly improved the oxidative stability, particularly for BSA stabilized emulsions. Therefore, RHPE could be employed along with the selected protein to increase physicochemical stability of emulsion.