ABSTRACT
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, ß-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 ß-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.
ABSTRACT
BACKGROUND: The effects of pulp extraction, thermal treatment and bulk storage of mango (Mangifera indica L.) and pineapple (Ananas comosus L.) pulps for 20 weeks at ambient (28 ± 2 °C) and cold (4 °C) temperatures on the bioactive phytochemicals and antioxidant activity were investigated. RESULTS: The contents of total polyphenols in mango (10.5%) and pineapple (5.4%) increased during pulping. The ratio of the degradation rate constants (kd values) (28 ± 2 °C: 4 °C) of vitamin C, polyphenols, Trolox equivalent antioxidant capacity (TEAC) and ß-carotene ranged from 2-4.5 and 1.5-2.7 in mango and pineapple pulps, respectively. The kd values of tannic acid, chlorogenic acid, epicatechin and catechin in mango pulp were 1.5-1.8 times higher under ambient storage than in cold storage. Furthermore, in pineapple pulp, the degradation rates of the same components were 1.6, 1.6, 2.1 and 1.4 times, respectively, faster at room temperature than in cold storage. The bulk storage of pulps at 4 °C provided better retention of health-promoting compounds than ambient temperature storage for up to 20 weeks. CONCLUSION: Bulk storage of mango and pineapple pulp under cold storage conditions (4 °C) is recommended as a better pulp preservation method than storage at ambient (28 ± 2 °C) temperature. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
