Antioxidant activities, anti-inflammatory, cytotoxic effects, quality attributes, and bioactive compounds of Ghanaian ginger under varied dehydration conditions

Abstract

This study sought to determine how different dehydration methods affect the quality of Ghanaian ginger. Slices of ginger rhizomes were subjected to freeze drying (FD), relative humidity convective drying (RHCD), infrared drying (IR), microwave drying (MC), and pulsed vacuum drying (PVD). The quality characteristics of the dried slices were assessed and compared based on their levels of selected gingerols or gingerol derivatives and their chromatic properties, antioxidant activities, and flavonoid content. Analysis of the chromatic properties of the dried samples revealed that the chroma value and hue angle values were highest for the samples subjected to FD (32.99, 88.13°) compared with those subjected to RHCD (28.90, 85.69°), IR (26.66, 83.79°), MC (24.36, 79.78°), and PVD (21.73, 78.96°). FD best preserved and retained the total flavonoid content (69.01 mg GAE/g db) and antioxidant activities evidenced by results of DPPH (124.53 mgTE/g db) and CUPRAC (90.71 mgTE/g db) determinations than the samples subjected to RHCD, IR, MC, and PVD. Finally, the cytotoxic and anti-inflammatory effects of extracts of the various dried ginger samples were evaluated using RAW 264.7 cells. Holistically, the samples from FD and RHCD gave the best outcomes for all the parameters compared. These two techniques are therefore recommended for large-scale application because they enhance the quality of ginger by maintaining its chemical integrity. These findings provide a deeper understanding of the different dehydration techniques as well as serve as a guide on the selection of the right drying technique for fresh ginger. Novelty impact statement: Ginger is one of the most extensively used spices in the world, but because of its high moisture content, it is usually dried to extend its shelf-life. For commercial purposes, an effective, safe, and efficient dryer is necessary to produce high-quality dried ginger. This dryer must be able to maintain the product quality while reducing processing time and energy usage. The findings of this study provide a deeper understanding of the different dehydration techniques as well as serve as a guide on the selection of the right drying technique for fresh ginger.