Optimization of osmotic dehydration in dragon fruit (Hylocereus Polyrhizus) slices using response surface methodology

Abstract

Dragon fruit (Hylocereus polyrhizus) is emerging as a super crop because of its several health and therapeutic benefits and ease of cultivation even in degraded land. Using response surface approach, the process parameters for osmotic dehydration of dragon fruit slices included process temperature, syrup concentration and process time. Slices of size 20 x 20 x 5 mm were dipped into sugar syrup with a syrup to dragon fruit slice ratio of 4:1 (w/w). After osmotic dehydration, the initial moisture content of dragon fruit samples was reduced to 27.5-68.49% (wb), demonstrating water loss, solid gain, and mass reduction in the range of 18.01-65.9%, 6.3-17.9% and 9.31-50.6%, respectively. After statistical analysis of the data on water loss, solid gain, and weight reduction, it was shown that regression equations of second order provided the greatest match for all the experimental data. With a syrup to fruit ratio of 4:1 and a syrup concentration of 65.3° Brix at a syrup temperature of 56.5°C, a maximum water loss of 58.2% and a minimum solid gain of 7.7% were expected to occur in 240 minutes of osmotic dehydration.