Greener approaches to improve phenolic acid composition and antioxidant activity of different cultivation methods of Zingiber officinale Roscoe extracts

Abstract

Zingiber officinale Roscoe, known as ginger (Bentong variety), is an essential spice ingredient used in food and condiments due to its refreshing aroma and intense flavour. The bioactive constituents found in ginger influence the numerous pharmacological effects, including antioxidant, analgesic, anticancer, antipyretic and anti-inflammatory. This work proposed a greener approach than the conventional plant matrices extraction to promote safe, non-toxic, and environment-friendly products. In this study, three different extraction methods: a) water (WE), b) hydrothermal-assisted (HAE) and c) enzymaticassisted (EAE), have been applied to measure the potential of both ginger extracts from different cultivation methods using fertigation technology and conventionally slopegrown. To ascertain the biological content of the extracts, the phenolic acid composition was quantified using ultra-performance liquid chromatography (UPLC). The total phenolic content (TPC) was determined using the Folin-Ciocalteu method, while the antioxidant activities were analysed using ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. The results obtained showed that ferulic acid was significantly highest in EAE extracts of both ginger (fertigation and slope-grown cultivation) at 1.165±0.118 and 0.610±0.062 mg/g. Moreover, EAE of both ginger extracts also found to be significantly highest in TPC (267.481±0.404 mg GAE/g and 247.837±1.675 mg GAE/g), and FRAP value (741.867±2.139 mg AAE/g and 461.733±0.231 mg AAE/g), respectively. However, the highest free radical scavenging activity of fertigated ginger extract through HAE was 134.735±0.021 mg AAE/g. Meanwhile, EAE of the sloped-grown ginger extract was highest at 141.293±0.707 mg AAE/g. This study demonstrates that EAE can be an effective approach in enhancing the TPC and antioxidant activity of ginger extracts. Ginger may therefore be suggested as a more greener and natural antioxidant to lessen oxidation in food products.