Texture and Pectin Content of Four Frozen Fruits Treated with Calcium

In this study, apple, mango, cantaloupe and pineapple cubes were immersed in a 1% calcium chloride solution before being frozen at −40C. The presence of calcium in these fruits did not significantly affect the total pectin content either before or after the freezing and thawing process, whereas it caused a decrease in the water soluble pectin content of all fresh and frozen-thawed fruits except for pineapple. For fresh fruit, calcium significantly increased the firmness of cantaloupe and mango. However, subsequent to freezing and thawing, only the frozen-thawed calcium treated mango had a significantly higher firmness and lower drip loss than the untreated samples. Calcium treatment did not cause changes to the microstructure of either fresh or frozen-thawed fruits. The firmness scores of the fruits tested by trained panelists corresponded with the results from the instrument and the panelists did not detect the bitterness of calcium chloride in the frozen-thawed samples. Practical Applications Freezing tends to disrupt the structure of living cells in fruit tissues which can cause poor texture and high drip loss. The findings of this study provide data as to the role of calcium on the physicochemical properties of frozen fruits. The application of calcium was appropriate on some frozen fruits. Both the instrumental analysis and sensory evaluation confirmed the suitability of the immersion in 1% calcium chloride to improve texture of frozen mango. This process did not cause a bitter taste in all frozen fruit samples. Since a diverse range of fruit types were used in this study, the results are broadly applicable.