Project Outline

The traditional thermal processing method, which is widely used in the food industry, can certainly destroy microbial cells and provide safe food. However, this process lowers the quality of food in terms of nutrition, taste and appearance. This is even truer in cases where we are dealing with spores and consequently, much higher temperature and exposure time is required. Therefore, food engineers are always on a mission to find new food processing techniques that can ensure food safety while maintaining food quality.

Ohmic heating is a promising novel food technology that potentially can be used for food sterilisation, enzymatic, blanching and thawing, fermentation and other processing technologies, and can maintain the freshness and flavour of foods to the utmost extent (Shan et al., 2017).

We already have developed an Ohmic Heating rig in our lab and applied ohmic heating to a wide range of food products including baking. We are interested to develop our knowledge on the following area of Ohmic Heating:

a. Mechanisms of Microbial Inactivation

b. Combined influence of temperature, pH and electric fields on the inactivation

c. Kinetics of Microbial Inactivation of key pathogenic microorganisms

d. Validation/Critical Process Factors

Exact project details will be agreed between supervisors and students at a later date.

References

Miri, T., Tsoukalas, A., Bakalis, S., Pistikopoulos, E. N., Rustem, B. & Fryer, P. J. (2008) Global optimization of process conditions in batch thermal sterilization of food. Journal of Food Engineering, 87(4), 485-494.

Porras-Parral, G., Miri, T., Bakalis, S. & Fryer, P. J. (2012) The effect of electrical processing on mass transfer in beetroot and model gels. Journal of Food Engineering, 112(3), 208-217.

Shan, C., Li, F., Wang, S., Zhao, Z., Chen, C., and Wu, H. (2017). Progress in the application of ohmic heating technology in food processing. Food and Fermentation Industry. 10: 274-281.

Baysal, A. H., and İçier, F. (2010). Inactivation kinetics of Alicyclobacillus acidoterrestris spores in orange juice by ohmic heating: effects of voltage gradient and temperature on inactivation. Journal of food protection. 73(2): 299-304.

Techniques

We typically use:

• molecular biology;
• microscopy (light/fluorescence / confocal / Raman);
• flow cytometry;
• chemical and biological assays;
• pulse-field gel electrophoresis (PFGE);
• bioreactor culture; and
• several inactivation techniques such as ohmic and microwave heating and ultra-sonication.