Research on soft solid microstructures is led by Ian Norton (professor, 2006-present). The research underpinning its continued impact seeks to understand how 1. phase inversion/colloidal structures, 2. fat crystallisation, 3. mixed biopolymers, 4. sheared/fluid gels, 5. Pickering emulsions, and 6. duplex or air-filled emulsions can be designed to have positive health benefits. It both informs and responds to industry demand for healthier alternatives to conventional food products.
The key research finding is the fundamental mechanistic understanding of emulsion behaviour in flow. This enabled process engineers to apply the kinetics of phase change and hydrocolloid physical chemistry to fat-continuous products. The work, initiated by Pacek (professor, 2006-2018), and continued by Norton, with Spyropoulos (PDRA 2006-2010, senior lecturer 2010-present), Mills (PDRA 2013-2015, lecturer 2015-present), Pelan (professor, 2018-present) and Wolf (professor, 2018-present), was fundamental in enabling industry to develop a self-catalytic inversion process by controlling and manipulating fat crystals at the oil/water interface. Because of UoB’s research, inversion is now temperature controlled (not time controlled) allowing rapid inversion and continuous production of products such as low and very low-fat spreads.
This work continues to produce new impacts through industry uptake, new product development, and consultancy. For example, research into phase-separating biopolymer systems and the control of these via process conditions (Spyropoulos) led to the ability to produce zero-fat spreads which are stable on storage and break down when consumed to give the physical properties and flavour release expected from margarine. The process has been adopted in the USA and UK by Unilever.
Research into fluid gels (Spyropoulos, Norton, Wolf, Pacek), where the structuring of hydrocolloids is carried out in different flow regimes, continues to generate impact (Kraft, Unilever, Cargill, Science in Sport). Particles formed on a microscale can replace fat in emulsions, be used for novel foam stabilisation, [and deliver controlled and sustained energy release for sports and health foods]. Recently, research in this area has led to the development of new techniques for the production of thermo-stable fluid gels (Norton). An enhanced understanding of the molecular events occurring during fluid gel formation has allowed the production of small (<10 μm), spherical and reasonably soft particles which resemble oil droplets. These particles, when used in emulsion-based products to replace a significant proportion of the oil, show rheology matching that of the full-fat original. The potential of fluid gels to impart sensory attributes typically associated with fat has led to their use by Rich Products and Bakkavor.
Work on fat-reduced emulsions has led to patented technology for both chocolate (Fryer, professor, 1994-present) and bakery fats (Norton, Spyropoulos), and is in continued use by PepsiCo and Pladis. The ongoing impact of research into Pickering emulsions to engineer crystallisation processes and understand the physics of particles at interfaces that can resist osmotic forces and so segregate sugars and water or salt and water to allow up to an 80% salt reduction in snacks, has led to new PepsiCo products. Finally, research on duplex emulsions (Norton), based on the physical chemistry and microstructure of shell formation around droplets, has reduced the hidden fat in foods (Kraft).