Mills, Thomas Benjamin (2012)
Ph.D. thesis, University of Birmingham.
Manufacturers are under pressure to reformulate products to make healthier foods, without changing desirability or flavour. A better understanding of product breakdown under oral conditions is essential to structure novel products which are healthier without consumers noticing. In-vitro methods were developed to explore product behaviour when subject to a range of phenomena relevant to those in the mouth, with particular emphasis on lubrication behaviour. Polysaccharides common in food products were mainly used as model systems and salt release was studied in some systems. Three in-vitro systems were developed and used in this study. Firstly, a stirred vessel was developed to gather data of salt release from gelatin, gellan and alginate systems, under quiescent conditions. This was a reliable method of tracking diffusion of sodium ions through the gel structures into a surrounding liquid, showing that diffusion was unaffected by the differing structure of the gels. The second system introduced the effect of compression. Only when pressures are sufficient to rupture the gel samples did compressions affect salt release over that observed in the stirred vessel study. Samples released the majority of their contained salt up to nine times faster, as a result of greater surface areas being exposed. Finally, tribology equipment was developed, which explores the thin film, high shear behaviour of materials. An exploration of available equipment, processing parameters and configurations was carried out to determine optimum surfaces, normal forces and speed ranges which could be related to phenomena occurring in the mouth. The lubricating properties of inhomogeneous polysaccharides with different physical properties were studied. The mixing behaviour of the polysaccharide greatly affected the lubrication response; some mixed quickly so lubricated more efficiently and vice versa. Finally, the developed tribology equipment was used to study the ordering process of a series of fluid gel samples, indicating that lubrication tracks the ordering process, with a decrease in lubrication when structure forms. The pattern of this response is a result of polysaccharide and salt content of the materials, with increasing content enhancing the change in lubrication experienced as more rigid gel particles are produced. The work presented in this thesis shows that the use of in-vitro methods can provide repeatable information on structure behaviour under conditions relevant to the mouth. This information could then be used to develop and assess future food products for their expected performance when consumed.
|Type of Work:||Ph.D. thesis.|
|Supervisor(s):||Bakalis, Serafim and Norton, Ian|
|School/Faculty:||Colleges (2008 onwards) > College of Engineering & Physical Sciences|
|Department:||School of Chemical Engineering|
TD Environmental technology. Sanitary engineering
TP Chemical technology
|Institution:||University of Birmingham|
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