Osmotic assisted convective drying of pomegranate arils: Process optimisation, structural characterisation, and bioactive compound evaluation

Abstract

Convective drying of pomegranate arils is time-consuming, energy-intensive, and affects the quality. Osmotic pre-treatment has been resorted prior to convective drying to improve drying performance and quality. In the present work, the osmosis factors such as temperature (30 - 60°C), time (50 - 250 min), and total soluble solids (TSS) (40 - 60°B) were studied using Box-Behnken design of response surface methodology. The quadratic models obtained adequately explained the process, and the optimum conditions were temperature (48.52°C), time (209.65 min), and TSS (51.31°B). The osmotic pre-treatment at optimum conditions followed by the convective tray drying reduced the drying time by nine hours, and the mean energy consumption by 0.172 MJ/g. Light microscopy revealed rupture and breakage of the honeycomb-like cellular structure of the pomegranate aril. Quality analysis of dried arils revealed that the texture (softness) and TSS improved by 11.75 N and 4.2°B, respectively. Likewise, sensorial quality parameters such as taste, mouth feel, and overall acceptability of the OATD (osmo-assisted tray-dried) arils significantly improved over the TD (tray-dried). However, there was a minor higher loss of 15.48, 12.52, and 15.88% in anthocyanin, phenols, and antioxidant capacity in OATD compared to TD. The OATD arils can be stored for up to six months in a modified atmosphere package (MAP).