Author : Nguyen Le Phu

Summary : Heat penetration, thermal death time and cut out tests were conducted as a means of establishing mathematically the optimum processing time for solid packed canned yellowfin tuna (Neothunnus macropterus) in oil. The heat penetration study showed the slope of the most probable slowest heating curve to be 34.55 minutes and that of fastest cooling curve to be 25.76 minutes. In the thermal death time study, suspensions of PA 3679 spores in screw cap test tubes were used and a Dr value of 1.6 min and a z value of 20 °F were obtained. Based on these data, the methods given by Stumbo and Ball were used to calculate the process time at 250°F for 307 x 201.25 can. The minimum process time obtained were 47.52 minutes for Stumbo's method and 52.8 minutes for Ball's method. Routine cut-out examination of samples stored at ordinary temperatures, 55°C and 30°C failed to show whether or not the calculated process time could give safe and sound products.