Malays. J. Anal. Sci. Volume 29 Number 2 (2025): 1260

Research Article

The effects of the mixing method on the formation and stability of oil-in-water (O/W) emulsions

Hanis Zafirah Fahizan¹, Hairul Amani Abdul Hamid^1*, and Ayub Md Som^2,3

¹School of Chemistry & Environment, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

²School of Chemical Engineering, College of Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

³Industrial Process Reliability and Sustainability Research Group (INPRES), College of Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

^*Corresponding author: h.amani@uitm.edu.my

Received: 29 July 2024; Revised: 15 December 2024; Accepted: 17 December 2024; Published: 8 April 2025

Abstract

Emulsion is a combination of two or more immiscible liquids, often oil and water. It is widely utilized in several fields including food, personal hygiene, cosmetics and pharmaceuticals. The stability of an emulsion is affected by various factors including water content, oil type and surfactant presence. The stability of an oil-in-water (O/W) emulsion mixture was tested with different mixing methods. The physical parameters of the O/W emulsion were evaluated using a creaming index measurement and tensiometer while the functional group was determined with Fourier Transform Infrared (FTIR) spectroscopy. The lowest creaming indices for ultrasonic and vortex mixers were sample C at 66.67% and sample F at 65.79%, respectively. Both samples contained rice starch and methyl-α-D-glucopyranoside (MGP). For the characterisation of surface tension, sample C in the ultrasonic mixer and sample F in the vortex mixer had the lowest number of surface tensions, which indicated the most stable emulsion. The functional group of samples was also carried out and the results of all samples showed almost the same distinct peak of the alcohol group from 3268 cm^-1 to 3300 cm^-1, which was from rice starch and MGP, and a sharp peak at the wavelength from 1634 cm^-1 to 1636 cm^-1 for alkene stretching vibrations. There were peaks presented between 1153 cm^-1 and 1154 cm^-1 that indicated the ether group in all samples except samples B and E. From these tests, the samples that showed the best stability were those with the presence of rice starch and MGP, namely samples C and F. These findings demonstrate that the selection of the mixing method significantly influences the stability of O/W emulsions. Future research should focus on refining these methods and exploring their scalability for various industrial applications.

Keywords: oil-in-water emulsion, mixing method, vortex mixer, ultrasonic mixer, stability of emulsion

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