Kinetic of softening of carrot by gamma radiation

Raw carrots were diced into 9.5 mm cubes, and subjected to gamma radiation between an array of Co60 pencils. A series of doses ranging from 0 to approximately 50 kGy was given. A plot of log (extrusion force) versus dose showed two distinct regions; the first is a rectilinear plot with a steep negative slope for doses up to about 15 kGy. The second is also a rectilinear plot with a shallow negative slope beyond 15 kGy. Sixty-seven percent of the firmness is lost with the first 15 kGy but only 4% of the firmness is lost with the highest 15 kGy increase in dose. This two-stage softening rate curve is consistent with the model of two first-order kinetic rate processes and is qualitatively similar to that for thermal softening of carrot. The term "radiation firmness" is proposed to describe the amount of firmness that is resistant to degradation by irradiation