Effects of gamma irradiation on the texture of minimally processed apple slices

Fresh-cut apples with or without calcium treatments were irradiated at doses up to 5 kGy at 0.4 and 2 kGy.h^-1 dose rates with a Co⁶⁰ source in 0, 21, and 100% O₂ atmospheres. Firmness decreased as irradiation dose increased beyond a 0.34 kGy threshold. High dose rate initially resulted in less softening compared to low dose rate, but dose rate became insignificant upon storage. Irradiation atmosphere did not affect firmness. Softening of irradiated slices correlated positively with water-soluble pectin, and negatively with oxalate-soluble pectin content. Calcium prevented irradiation-induced softening of thin slices (3-4 mm thick), but was not effective with thicker wedges due to limited penetration.