The use of ultrasonics for nanoemulsion preparation

Abstract

Oil-in-water emulsions are an important vehicles for the delivery of hydrophobic bioactive compounds into a range of food products. The preparation of very fine emulsions is of increasing interest to the beverage industry, as novel ingredients can be added with negligible impact to solution clarity. In the present study, both a batch and focused flow-through ultrasonic cell were utilized for emulsification with ultrasonic power generation at 20-24 kHz. Emulsions with a mean droplet size as low as 135 ± 5 nm were achieved using a mixture of flaxseed oil and water in the presence of Tween 40 surfactant. Results are comparable to those for emulsions prepared with a microfluidizer operated at 100 MPa. The key to efficient ultrasonic emulsification is to determine an optimum ultrasonic energy intensity input for these systems, as excess energy input may lead to an increase in droplet size.Industrial relevance: The preparation of oil-in-water emulsions is a common feature of food processing operations. The use of ultrasound for this purpose can be competitive or even superior in terms of droplet size and energy efficiency when compared to classical rotorstator dispersion. It may also be more practicable with respect to production cost, equipment contamination and aseptic processing than a microfluidisation approach. The present paper shows that ultrasound can be effective in producing nanoemulsions for use in a range of food ingredients.

Application of ultrasound to microencapsulation of coconut milk fat by spray drying method

“…The application of low frequency ultrasound is known to cause acoustic cavitation which plays an important role in the reduction of primary droplets of oil-in-water emulsion (Kentish et al 2008). Therefore, it would be expected that increase in ultrasonic power would improve the amount of shear force that breaks up primary droplets into the smaller ones.…”

“…High pressure homogenization is a method of choice commonly used in many researches for enhancing the stability of coconut milk emulsion (Chiewchan et al 2006;Coupland 2008, 2009) and for preparing stable emulsion before spray-drying (Hogan et al 2001;Liu et al 2001;Yoshii et al 2001). Recently, the use of ultrasound for homogenization of oil in water emulsion has attracted considerable attention (Kentish et al 2008;Leong et al 2011). In addition, ultrasound had a very good homogenization effect at high power levels compared with high pressure homogenization (Wu et al 2000).…”

Characterization of flaxseed oil emulsions

“…One or few drops of emulsion were dispersed into 600 mL distilled water to obtain an obscuration of 0.2 %. A refractive index of 1.475 was used for flaxseed oil (Kentish et al 2008). The particle size distribution of emulsion at day 1 and day 30, respectively was measured.…”

Effects of ultrasound time on the properties of methylcellulose-montmorillonite films

“…Several chemical reactions can occur between these active radicals and substances in the medium. Finally, more chemical bonds, like H and covalent bonds will be generated [14,16,17].…”