Effect of different thermal and non‐thermal pre‐treatments on bioactive compounds of aqueous ginger extract obtained using vacuum‐assisted conductive drying system

Abstract

The current study investigates the effect of microwave (MW), Ohmic heating (OH), and ultrasound (US) pre‐treatments on the extraction of bioactive compounds and the drying kinetics of ginger using a vacuum‐assisted conductive drying system. The US pre‐treatment produced acoustic cavitation, and microstreaming in ginger slices which enhanced the total phenolic content and radical scavenging activity of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) (i.e., 14.83 ± 0.03 mg GAE/ml and 57.37 ± 0.00%) in obtained aqueous ginger extract (AGE). Similarly, OH pre‐treatment improved the total flavonoids content (i.e., 8.99 ± 0.01 mg QE/ml) of the acquired AGE. The pre‐treatments modified the surface of ginger which eventually led to better moisture diffusivity ratio of 2.58E−08 and 2.01E−08. Furthermore, the GCMS analysis of OH pretreated AGE reported more bioactive compounds compared to MW, US, and control. The major bioactive compounds reported were linalool, neral, geraniol, endo‐borneol, and 2,4 di‐tert‐butyl‐phenol which possess several therapeutic benefits. Thus, the US and OH pre‐treatments effectively enhanced the drying and extraction of bioactive compounds from ginger. Further studies are warranted on the obtained extract to understand its maximum potential for application in food and pharmaceutical industry. Practical applications The ginger extract collected while drying can be used as a flavoring agent or can be incorporated into drinks to enrich the bioactive compounds. The GCMS results indicate that volatile compounds entrapped in the condensate collected contains bioactive components with antioxidant properties. These bioactive compounds can be further studied for their potential health benefits in humans. Thus, this condensate obtained using vacuum‐assisted conductive drying system helps in utilizing the nutrients that are lost and goes unutilized during drying in many industries.

Optimization of an Ultrasound-Assisted Extraction Method for the Extraction of Gingerols and Shogaols from Ginger (Zingiber officinale)

“…Finally, the solvent should also be readily available in substantial quantities and at a low cost as well as suitable for environmentally safe disposal [27]. In any case, UAE is expected to be highly effective in the extraction of gingerols and shogaols due to its ability to penetrate the intricate plant matrix with ultrasonic waves, thus effectively breaking down the cell walls and releasing the desired compounds [28]. In addition, the cavitation process enhances mass transfer, resulting in a higher yield of gingerols and shogaols, thus ensuring that the extraction process is efficient and successful.…”