Thepkunya Harnsilawat

Influence of Biopolymer Emulsifier Type on Formation and Stability of Rice Bran Oil‐in‐Water Emulsions: Whey Protein, Gum Arabic, and Modified Starch

Rice bran oil (RBO) is used in foods, cosmetics, and pharmaceuticals due to its desirable health, flavor, and functional attributes. We investigated the effects of biopolymer emulsifier type and environmental stresses on the stability of RBO emulsions. Oil-in-water emulsions (5% RBO, 10 mM citrate buffer) stabilized by whey protein isolate (WPI), gum arabic (GA), or modified starch (MS) were prepared using high-pressure homogenization. The new MS used had a higher number of octenyl succinic anhydride (OSA) groups per starch molecule than conventional MS. The droplet diameters produced by WPI and MS were considerably smaller (d < 300 nm) than those produced by GA (d > 1000 nm). The influence of pH (3 to 8), ionic strength (0 to 500 mM NaCl), and thermal treatment (30 to 90 °C) on the physical stability of the emulsions was examined. Extensive droplet aggregation occurred in WPI-stabilized emulsions around their isoelectric point (4 < pH < 6), at high salt (> 200 mM, pH 7), and at high temperatures (>70 °C, pH 7, 150 mM NaCl), which was attributed to changes in electrostatic and hydrophobic interactions between droplets. There was little effect of pH, ionic strength, and temperature on emulsions stabilized by GA or MS, which was attributed to strong steric stabilization. In summary: WPI produced small droplets at low concentrations, but they had poor stability to environmental stress; GA produced large droplets and needed high concentrations, but they had good stability to stress; new MS produced small droplets at low concentrations, with good stability to stress. Practical Application: This study showed that stable rice bran oil-in-water emulsions can be formed using biopolymer emulsifiers. These emulsions could be used to incorporate RBO into a wide range of food products. We compared the relative performance of whey protein, GA, and a new MS at forming and stabilizing the emulsions. The new OSA MS was capable of forming small stable droplets at relatively low concentrations.

Influence of Polyglycerol Polyricinoleate and Biopolymers on Physical Properties and Encapsulation Efficiency of Water-in-Oil-in-Water Emulsions Containing Mango Seed Kernel Extract

The influence of polyglycerol polyricinoleate (PGPR) and biopolymers (gelatin and sodium alginate) on the stabilization of water-in-oil (W/O) emulsions was investigated to improve the encapsulation efficiency (EE) of water-in-oil-in-water (W/O/W) emulsions containing mango seed kernel extract (MSKE). The physical properties and EE of the emulsions were found to depend more strongly on PGPR than on biopolymers. High EE values of MSKE were obtained when W/O emulsions stabilized by 4–8 wt% PGPR were incorporated with 1–5 wt% gelatin, or by 6–8 wt% PGPR incorporated with 0.5–1.5 wt% sodium alginate in the inner aqueous phase. GRAPHICAL ABSTRACT

The Physical Characterization and Sorption Isotherm of Rice Bran Oil Powders Stabilized by Food-Grade Biopolymers

Rice bran oil (RBO) is used in several products in the food, cosmetics, and pharmaceutical industries due to its desirable health, flavor, and functional attributes. The formation and physicochemical properties of microencapsulated RBO stabilized by different biopolymers were investigated. Oil-in-water emulsions (10% RBO, citrate buffer pH 7) stabilized by either 3.5% whey protein isolate (WPI) or 7.0% modified starch (MS) containing maltodextrin (DE18) as a carrier agent were initially prepared. The diameter of emulsion droplets produced by WPI and MS were considerably smaller than 300 nm and 25 μm for dried particles. The resulting powders had poor to fair flowability and high cohesiveness characteristics: Carr index (27–37) and Hausner ratio (1.4–1.6). The microencapsulation efficiency of the spray-dried powders ranged from 92–95%. Moisture sorption isotherms of the powders were determined by a gravimetric method, while their glass transition temperatures (Tg) were determined by differential scanning calorimetry. The experimental water adsorption data were fitted to BET and GAB models. The GAB model fitted better the measured moisture isotherm than the BET model (R2 = 0.99). Powders produced with MS showed higher water adsorption than those stabilized by WPI. Powders produced with WPI had a higher glass transition temperature than those produced with MS. Measurements of lipid deterioration in the RBO powder during storage showed that the reaction order was different for WPI-stabilized (n = 1) and MS-stabilized (n = 0) RBO powder. These results have important consequences for the creation of food-grade powders containing functional lipids such as RBO application.

Interaction of Tamarind Kernel Powder, Gum Arabic and Maltodextrin in Aqueous Solution and Microencapsulated Systems

The combination of polysaccharides as wall materials affects the stability of microcapsules. One of several factors influencing the stability is related to interaction between polysaccharides. The interaction of tamarind kernel powder, gum arabic and maltodextrin was obtained by UVVisible spectrum and apparent viscosity in solution and on the aggregation of the W/O/W emulsions from encapsulation efficiency, creaming index, droplet size, ΖPotential, viscosity and microstructure analysis. The experimental results indicated that there are interactions between each polysaccharide. In the solution system, peak occurred at 210 nm for a solution mixture from 0.1%gum arabic, 10.00% maltodextrin and 0.02%tamarind kernel powder. Moreover, the synergistic viscosity increase was also observed. Interestingly, a combination of three polysaccharides in W/O/W emulsion exhibited the lowest creaming rate, the largest droplet, one peak of size distribution, and gave high encapsulation efficiency and the highest viscosity value compared to single and binary combination of each polysaccharide treatment. The results suggest that the interaction between tamarind kernel powder, gum arabic and maltodextrin is responsible for the stability enhancement of microencapsulated system.