Liquid mass transport in skipjack tuna muscle (Katsuwonas pelamis) during canned tuna processes

The United States canned tuna industry produces over a billion cans annually. The goal of this research project was to study physicochemical properties and mechanisms involved in liquid mass transport in skipjack tuna muscle during three different unit operations critical to cannery performance.; Heat and mass transfer through tuna muscle were studied during atmospheric steam cooking. Moisture content, temperature and fillet mass were measured in skipjack muscle during cooking. Thermal denaturation temperatures of muscle proteins were measured using differential scanning calorimetry. Moisture content and mass loss rates were dependent on muscle temperature. Moisture loss resulted from thermally-induced denaturation of muscle proteins and subsequent shrinkage, followed by moisture transport to the muscle surface. The temperature gradient through the muscle resulted in a gradient of muscle protein and tissue changes to produce changes in mass loss rates.; Liquid mass transfer in skipjack meat was investigated during retorting and five weeks of storage. Moisture content and mass loss in previously cooked tuna muscle chunks canned in water were determined. Cans with tuna pieces were retorted to equivalent lethality for different time and temperature processes. Retorting at the lower temperature, longer time resulted in a lower mass loss than higher temperature, shorter time processes. Canned storage up to five weeks did not significantly change mass nor moisture content. Mechanisms for physicochemical changes responsible for mass changes were discussed.; Tuna can fill weight is regulated by an empirical, mechanical press test method. Fundamental characteristics and effects of retorted skipjack tuna muscle properties on liquid mass loss during expression are unknown. Test equipment and procedures were developed. Compressive force, cake height, and expressed liquid mass and viscosity data were collected. Changes in material properties during expression were described and piece size, liquid viscosity, and precooking treatment effects on mass retention were determined. Abusive precooking resulted in increased loss of mass and solids. Pressed cakes of large chunk muscle pieces were unaffected by increased liquid viscosity, while increasing liquid viscosity increased mass and moisture retention in small flake piece pressed cakes. The impact on canned tuna fill compliance and product quality attributes was discussed.