Conservation of minimally processed pineapple using calcium chloride, edible coating and gamma radiation

The aim of this study was to obtain a convenience type pineapple subjected to fresh-cut process and calcium chloride, wheat gluten and alginate-base edible coating and irradiation treatments. The fruits were washed, sanitized with Sumaveg (Sodium Dichloro-s-Triazinetrione) in a 200 mg L-1 chlorine-free solution at 7 deg C for 15 minutes, and then manually peeled. The peeled fruits were sliced into 1 cm thick slices, rinsed in 20 mg L-1 chlorine-free solution for 3 minutes and drained for 3 minutes. In the first experiment, the samples were treated with: 1% calcium chloride + vital wheat gluten solution; 1% calcium chloride + 1% alginate solution; and control. In the second experiment, the samples were treated with: 1% calcium chloride + vital wheat gluten solution + 2.3 kGy; 1% calcium chloride + 2.3kGy; irradiation with 2.3kGy; and control. The packing consisted of rigid polyethylene terephthalate (PET) trays with around 250 g of fruit. The irradiation was performed in a Cobalt-60 multipurpose irradiator with 92 kCi activity and dose value of 2.3 kGy h-1. The samples were stored at 5 ± 1 deg C and evaluated every other day for 12 days. In the first experiment pH and titratable acidity values showed slight variations but were similar between the treatments. There was a decrease in ascorbic acid values in all treatments. Browning was noticed in all treatments over the storage period. Although the values between the treatments were similar, the pineapple treated with calcium chloride + gluten showed firmer texture, less liquid loss, and lower values of polyphenoloxidase and peroxidase activities and CO2 and ethylene production. Mesophiles and mold and yeast counts were also reduced. No Salmonella and E. coli were detected. Total coliform counts were low in all the treatments and appeared in just a few isolated samples during the storage period. Sensory analyses showed that the samples treated with calcium chloride + gluten had the lower scores for texture, appearance, and aroma; the flavor was compromised from the 4th storage day onward. In the second experiment the pH and titratable acidity values showed small changes but were similar between the treatments. There were a decrease in the ascorbic acid values in all treatments; nevertheless, the samples treated with calcium chloride + gluten + 2.3 kGy retained more of this vitamin than the other treatments. Firmer texture, less liquid loss, and lower values of polyphenoloxidase and peroxidase activities were noticed in the samples with calcium chloride + 2.3 kGy. Browning was noticed in all treatments over the storage period. The darker samples were the ones treated with calcium chloride + gluten + 2.3 kGy, and irradiated with 2.3 kGy. Higher respiratory rate and ethylene synthesis were noticed in the samples treated with calcium chloride + gluten + 2.3 kGy. The lowest psychotropic, mesophiles, and mold and yeast counts occurred in the samples treated with calcium chloride + gluten + 2.3 kGy. No Salmonella and E. coli were detected. Total coliform counts were low in all the treatments and appeared in just a few samples during the storage period. Only the control kept the sensorial attributes within the acceptability limit during the storage period. The texture in all the other samples was unacceptable from the 8th day onward. The flavor was compromised from the first storage day onward in the samples with calcium chloride + gluten + 2.3 kGy (author)