This book investigates the use of the emerging food preservation technique, ‘High Pressure Processing (HPP)’ for ‘Greenshellâ„¢ mussels (Perna canaliculus)’ to replace the existing thermal processing which has negative impacts on quality. Mussels can become high risk food if contaminated with food-borne pathogen Listeria monocytogenes, the causative agent of listeriosis. Two major objectives were undertaken within this study: Safety and Quality. Food safety was addressed by measuring and modelling the effects of HPP parameters (as a function of pressure, temperature and time) on a pressure resistant strain of food-borne pathogen (L. monocytogenes FSA 2655). An effective treatment temperature of the system was used to determine the activation energies for inactivation of L. monocytogenes in mussel meat using HPP taking into account the temperature changes caused by adiabatic heating. Quality was determined by effect of HPP parameters on autolytic enzymes mussels viz. alanine aminopeptidase and lipase enzymes. The optimised processing parameters were then used to do quality assessment of end-product by measuring colour, texture, yield and sensory attributes during chilled storage.