Effect of Passive Drying on Ascorbic Acid, α-Tocopherol, and β-Carotene in Tomato and Mango

The effect of two passive drying methods on the degradation of ascorbic acid (vitamin C),  α-tocopherol (vitamin E), and β-carotene (provitamin A) in ripe mango and tomato was determined. Samples of both commodities were dried outdoors in a solar drying cabinet or indoors in sealed plastic boxes containing ceramic zeolite drying beads in a bead-to-fruit ratio of 1:10. Nutrient content of the dried samples was compared to fresh samples (undried control) obtained from the same batch of fruit. Mango samples tended to reach an equilibrium weight of approximately 18% of their initial weight after 28 to 30 hr of drying in both drying methods, while tomatoes equilibrated at 5% to 6% of their initial weight after 8 to 10 hr of drying in the solar drying cabinet and after approximately 30 hr using drying beads. The content of all three nutrients in solar dried tomato, and of β-carotene in mango were significantly (P < 0.05) lower than the control. α-Tocopherol and β-carotene content in tomato and β-carotene content in mango were significantly lower than the control in samples dried using drying beads. Drying method had a significant (P < 0.05) effect on nutrient content; ascorbic acid and β-carotene content were lower in solar dried tomato than in tomato dried with drying beads. For mango, β-carotene content was lower after solar drying as compared to drying with drying beads. Drying fruit at lower temperatures using drying beads resulted in higher overall nutrient content of the dried fruit.

Agriculturalists in developing countries still depend largely on solar drying methods as a means of extending the shelf life and increasing the value of fruit and vegetable products. Zeolite drying beads are reusable and are capable of drying fruit relatively quickly in a controlled environment, and may reduce the degradation of certain nutrients due to heat during solar drying.