EVALUATION OF FREEZING TEMPERATURES AND RIPENESS LEVELS ON THE QUALITY CHARACTERISTICS OF FROZEN PINEAPPLE FRUITS

Abstract

Freezing is considered an effective means to preserve fruits without using any chemical preservatives. In this study, the effects of ripeness levels and two freezing temperatures (-25oC and -86oC) on the frozen pineapples were evaluated. The faster freezing rate (0.4 oC/min) was obtained by the -86oC freezing system to achieve the core temperature of -18oC in frozen pineapple in ~0.65 h compared to that at -25oC with respective to freezing rate of 0.09 oC/min and freezing time of ~3 h. Freezing pineapple fruits at -86oC was found to reduce the drip loss, vitamin C, and structure loss compared to that at -25oC. Ripeness levels were found to cause significant impacts on the quality of frozen pineapples. The increase in ripeness level (level 1 to level 4) was found to cause the increment in freezing time, drip loss, and vitamin C loss. Meanwhile, frozen pineapple fruits the green maturity (ripeness level 1) were observed with lower structure retention compared to riper pineapple (level 2 to level 4). The total soluble solids (TSS) and titratable acidity of frozen pineapples were found to be insignificantly affected by the freezing temperatures and ripeness levels. The freezing system at -86oC for frozen pineapple was found to promote better performance in maintaining the quality of frozen pineapple products.