Understanding nanoemulsions

Nanoemulsions have been receiving a lot of interest due to their advantages: creaminess, better stability and more efficient delivery of neutraceuticals to the body. This work has developed the understanding of how to produce nanoemulsions efficiently using two high pressure devices: the industrially used high pressure valve homogeniser (HPH) and the efficient but hard to scale Microfluidizer. A range of different oil to aqueous phase viscosity ratios, emulsifier types, pressure drops and number of passes through the devices were tested. It was shown for O/W nanoemulsions the Microfluidizer produces the final droplet size after one pass whereas in the HPH coalescence was shown to be prevalent thus requiring several passes to reach the final droplet size. The geometry of these devices was shown to be the largest influence on homogenisation efficiency. Upon lowering the viscosity ratio, coalescence in the HPH was reduced and for the W/O emulsions produced, the efficiency was matched to the Microfluidizer, with both producing 50 nm minimum droplet diameters. This thesis concludes by researching two applications of nanoemulsions: (1) understanding flavour release within nanoemulsions and (2) inclusion of oil within fluid gels to reduce the bland flavour associated with fluid gels only. It was shown that up to 30% oil can be incorporated within the polysaccharide particles although the viscosity reduces with increasing oil inclusion. Additionally, the emulsifier type used to stabilise the oil influences the fluid gel properties with sodium caseinate producing the highest elastic modulus, compared to Tween 20 and to the least SDS