The effect of thermal processing on health-promoting phytochemicals was investigated in relation to the canning of mango and pineapple. The cans were retorted at four different temperatures for varying amounts of time. Vitamin C, β-carotene, polyphenols, flavonoid content, and antioxidant capacity in canned fruit pieces and sugar syrup were determined. The diffusion and leaching of phytochemicals were determined through mathematical modelling. Retention of vitamin C in canned pineapple pieces was higher than in canned mango pieces. Thermal treatment had an effect of rapidly reducing leached vitamin C. The activation energy required for the degradation of vitamin C and β-carotene in mango was higher than that required in pineapple. Trolox equivalent antioxidant capacity (TEAC) values at 130 °C (40 min) were 3.1 and 1.9 μmol Trolox/g FW in mango pieces and syrups, respectively, indicating that antioxidant leaching had occurred. The degradation constants of the phytochemicals studied were comparable but were slightly higher in pineapple than in mango. The investigated health-promoting phytochemicals in canned products were present in substantially lower concentrations than in fresh mango and pineapple.
Keywords: activation energy; antioxidant; degradation; flavonoids; β-carotene.