Effect of Drying on Antioxidant, Colour, and Total Chlorophyll of Wheatgrass (Triticum aestivum L)

Introduction: Powdered wheatgrass is a practical way to preserve nutrients and has a longer shelf life than juice. Methods: Wheatgrass was dried to investigate the effect of Freeze Drying (FD), Hot Air Oven Drying (HOD), and microwave drying (180 W, 300 W, and 600 W) on the phenolic compounds, antioxidant activity, colour, and total chlorophyll content of wheatgrass and to identify the costeffective and energy-efficient drying method. The study also analysed the best-suited drying model to dehydrate Wheatgrass (WG). Results: The dehydration kinetics of wheatgrass was most effectively described by the Wang and Sing model, with the lowest value of SSerror (0.0019-0.03102) and RMSE (0.01949-0.07876) followed by the Page model. Wheatgrass dried in freeze drying had higher levels of TPC (4.09 mg GAE/g), chlorophyll (27.66 mg/g), and DPPH scavenging ability (81.64%) compared to other dried samples due to the absence of high temperature as well as innate chromatic characteristics. Ascorbic acid, gallic acid, rutin, ρ-coumaric acid, and myricetin were identified by High-Performance Liquid Chromatography (HPLC). Discussion: Freeze drying enabled the highest preservation of bioactive compounds. However, it was an exceptionally energy-intensive process, requiring 45-150 times more energy per unit of moisture removal than other methods. Microwave Drying (MOD) methods not only achieved the highest moisture diffusivity and energy efficiency but also experienced limited deterioration in bioactive properties compared to HOD. The study assessed the effect of drying processes on the colour parameters (L*, a*, b*) and ΔE to estimate the colour deterioration during drying. The lowest value of ΔE was observed in the case of MOD at 180 W, indicating a very slight difference with the raw sample. Conclusion: FD was the most effective method, followed by microwave drying to prepare wheatgrass powder for everyday use. Innovations in drying techniques can improve efficiency and reduce processing time, and they are essential for use in various food and beverage manufacturing industries.