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 (-25^oC and -86^oC) on the frozen pineapples were evaluated. The faster freezing rate (0.4 ^oC/min) was obtained by the -86^oC freezing system to achieve the core temperature of -18^oC in frozen pineapple in ~0.65 h compared to that at -25^oC with respective to freezing rate of 0.09 oC/min and freezing time of ~3 h. Freezing pineapple fruits at -86^oC was found to reduce the drip loss, vitamin C, and structure loss compared to that at -25^oC. 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 -86^oC for frozen pineapple was found to promote better performance in maintaining the quality of frozen pineapple products.

Keywords: 

Freezing, frozen pineapple, ripeness level, fruit quality