Abstract:
The color of fresh tuna treated by 4% carbon monoxide +20% carbon dioxide +10% oxygen, or irradiated at 1 KGy or 2 KGy, or first gas treated then irradiated, was analyzed using the R, a∗ and hue parameters in a machine vision system. The percent of sample surface having R > Rthreshold, a∗ < a∗threshold, or hue < huethreshold was associated with storage time for different levels of threshold values. Hue was selected as the best representative of the red color of tuna. A method was suggested to select the threshold value of a parameter. Irradiation did not change the color of fresh tuna. Exposure to CO increased the redness, and preserved it for up to 12 days in refrigerated storage. Microbial numbers for CO treated tuna were not different from control. Irradiation at 2 KGy was very effective in reducing microorganisms, while 1 KGy was ineffective.