Drying of ginger slices—Evaluation of quality attributes, energy consumption, and kinetics study

Abstract

Ginger slices were dried with Freeze drier (FD), relative humidity convective drier (RHCD), infrared drier (IR), and microwave drier (MD) at a temperature of 60 C. The influence of the drying techniques on total phenolic content (TPC), total flavonoid content (TFC), antioxidant activities, ABTS (2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), DPPH (1,1-diphenyl-2-picrylhydrazyl), FRAP (Ferric reducing antioxidant power capacity), and CUPRAC (Cupric ion reducing capacity), rehydration ratio (RR), color, enzyme inactivation (polyphenol oxidase, PPO and peroxidase, POD), energy consumption rate (ECR), microstructure, volatile compounds (aroma profile), and drying kinetics were assessed. The results showed that FD-ginger slices retained the highest antioxidant properties, ABTS (51.88 mgTE/g db), CUPRAC (95.51 mgTE/g db), DPPH (132.95 mgTE/g db), and FRAP (95.32 mgTE/g db), TPC (118.70 mg GAE/g db) and TFC (98.94 mg CE/g db), preserved microstructure and higher volatile compounds compared RHCD, IR, and MD. The RHCD-ginger slices attained the highest RR (3.6), lowest ECR (7.88 kWh/kg), lowest PPO (17%), and POD (22%) residual activity with preserved color properties than FD, IR, and MD. RHCD also enhanced the drying kinetics and lessened the drying time compared to FD, IR, and MD. Page model best fitted the experimental results of drying kinetics (R 2 > 0.99). Practical applicationOne of the world's most consumed and used spices is ginger and due to its high moisture content, drying is normally used for its preservation. Therefore, to attain dried ginger of better quality, an effective, safe, efficient drier that can preserve product quality and reduce processing time, as well as energy consumption, is required for commercial purposes as a poor selection can have an adverse effect on the product quality. The outcome of the current investigation will offer a better understanding of various drying techniques and also provide more information on the selection of the best drying technique for drying ginger.

Effect of pulsed‐vacuum, hot‐air, infrared, and freeze‐drying on drying kinetics, energy efficiency, and physicochemical properties of Ginkgo biloba L. seed

“…For FD, their values were reported at an interval of 60 min. Equation (1a) estimated GBS's moisture ratio (MR) (Jahanbakhshi et al, 2020;Jiang et al, 2020): (Jahanbakhshi et al, 2020;Osae et al, 2020):…”

Heat and mass transport analysis of the drying of freshwater fishes by a forced convective air‐dryer

“…Although still subject to debate among researchers, it is imperative to define a suitable metric for energy efficiency and definition of energy efficiency during drying (Raghavan et al, 2005). Overall energy consumption and SMER are two most common methods, which can be calculated as instantaneous value with time and/or as an average over the whole drying time (Osae et al, 2020).…”

Drying of sliced tomato (Lycopersicon esculentumL.) by a novel halogen dryer: Effects of drying temperature on physical properties, drying kinetics, and energy consumption

“…Researchers found that the energy consumption rate for drying apple slices using relative humidity convective dryer ranged between 3.37 and 5.36 kWh/kg (Shewale et al, 2019). It was also reported that the energy consumption rate for drying ginger slices using freeze drying, relative humidity convective dryer, infrared dryer and microwave dryer was 20.24, 7.86, 10.37, and 9.63, respectively (Osae et al, 2020).…”

“…Specific energy consumption is given by Equation (23) (Osae et al, 2020; Shewale, Rajoriya, & Hebbar, 2019): where, SEC is the specific energy consumption (kJ/kg), P is the consumed (given) power (kW), t is the time (s), and M w is the mass of water evaporated from tomato (kg).…”