Modeling the impregnation of roselle antioxidants into papaya cubes

Abstract

The increasing demand for healthy foods has recently encouraged research focused on incorporating antioxidant compounds from bioactive-rich sources into other foodstuffs; however, the studies aimed at modeling the mass transfer occurring during the enrichment of food matrices with bioactive substances remain scarce. This work investigated the modeling of water loss, solids gain, impregnation of bioactive compounds - total phenolics (TPC) and total anthocyanins (TAN) - and changes in total antioxidant capacity (TAC) of papaya cubes infused with a roselle extract/sucrose solution (RESS). The RESS was used to impregnate 15 mm papaya cubes in the mass ratio of 15:1 at 45, 55 and 65 °C for different immersion times (0, 10, 15, 30, 60, 90, 120, 180, 240, 300, and 360 min). A novel semi-analytical solution for the unsteady-state diffusion equation considering the product shrinkage was proposed for describing experimental mass transfer data and for obtaining equilibrium points and effective diffusivities of migrating species. After 360 min, RESS-impregnated papaya cubes increased their TPC, TAN, and TAC in about 670–990 mg GAE/100 g fresh weight (FW), 48.8–65.0 mg C3G/100 g FW, and 805–1004 mg TE/100 g FW from 402 ± 53 mg GAE/100 g FW, 0 mg C3G/100 g FW, and 679 ± 62 mg TE/100 g FW. Diffusivities for water, total solids, TPC, TAN, and TAC were in the ranges of 1.76–12.6, 0.90–2.54, 0.65–10.8, 0.36–1.32, and 3.31–11.1 ( × 10−10) m2/s, respectively. These values were overestimated in about 23 ± 6% when papaya shrinkage, accounting up to a 50% volume loss, was not considered in the calculations.