Improvement of Oxidative Stability of Rice Bran Oil Emulsion by Controlling Droplet Size

Abstract

Well‐planned emulsification studies are needed to improve oxidative stability of rice bran oil. Factors that affect the droplet size during emulsification of rice bran oil include the amount of rice bran oil content, types of emulsifiers, power intensity and duration of sonication. In this study, the emulsions were prepared at different oil concentrations (10, 15 and 20%), using different emulsifiers (Tween 80 and its mixtures with Span 80), and subsequently sonicated at different durations (5–50 min). Longer sonication time resulted in smaller‐sized emulsion droplets. The emulsions with the mixture of Tween 80 and Span 80 formed smaller droplets and better oxidative stability than those with Tween 80 only. In conclusion, rice bran oil emulsion with smaller droplets improves oxidative stability. This study may be helpful for tailoring oxidative‐stable emulsions with well‐defined droplet size distribution. PRACTICAL APPLICATIONS Recently, food manufacturers have been interested in utilization of the polishing by‐products such as rice bran. Rice bran oil contains well‐balanced saturated and unsaturated fats and provides a good source of vitamin E, antioxidants, oryzanol and other micronutrients. However, food application of rice bran oil is limited because of lipid oxidation. One of the promising technologies is nanoemulsion fabrication, which is being applied to enhance the oral bioavailability and oxidative stability of the poorly water‐soluble bran oils. Herein, attention is focused on improving oxidative stability by controlling droplet size through adding mixture of surfactants in the oil‐in‐water emulsion. Narrow size distribution of droplets is a challenge for improved oxidative stability. In this study, proper formulations such as a mixture of emulsifiers provide a resolution to overcome the oxidative stability limitations in utilization of rice bran oils.

Antioxidant activity and bioaccessibility of size-different nanoemulsions for lycopene-enriched tomato extract

“…Both anti-radical activity and oxidative stability of the lycopene nanoemulsions with droplets smaller than 100 nm were effective for a long time and suitable for sustained delivery. These results are in agreement with the findings of previous studies that observed that the retardation of lipid oxidation and the enhancement of bioactivity are critically related to the surface property of the droplets in the emulsion (Mei, McClements, Wu, & Decker, 1998;Nguyen, Choi, Kim, Kang, & Ko, 2013;Yoshida & Niki, 1992). These smaller-size droplets may be structurally favorable for enhanced transparency, improved aqueous stability, and controlled release, thereby preserving the bioactivity of lycopene in foods.…”

Formation, antioxidant property and oxidative stability of cold pressed rice bran oil emulsion

“…The fact that the droplets have a high negative charge is important for certain applications, since it affects the physical and chemical stability of emulsions (Karraker and Radke 2002;McClements 2005). The CPRBO emulsions stabilized by GMS had larger negative zeta potential than RBO emulsions stabilized by whey protein, gum Arabic, or modified starch (Charoen et al 2011) or by Tween 80 and Span 80 (Nguyen et al 2013). This may have been due to differences in the type of ionized species adsorbed at the oil-water interface, or due to differences in solution properties (such as pH and ionic strength).…”

Optimization of Homogenization–Evaporation Process for Lycopene Nanoemulsion Production and Its Beverage Applications

“…High zeta potential indicates that emulsion surface is sufficiently and completely covered with surfactants which will intern act as an effective barrier to avoid the contact of oxidation initiators on surface of the emulsion. Several authors have found that the oxidative stability of an emulsion depends on the surface charge of the lipid droplet at which oxygen reacts with the lipid inside the droplet (Yoshida and Niki ; Mei ; Nguyen ). In conclusion, a nanoemulsion with droplets smaller than 100 nm exhibited higher stability and better protection against reactions with oxygen and free radicals in the emulsion.…”