Comparative Bioactivities of Essential Oils from Kaffir Lime Peel Wastes and Bentong Ginger Rhizomes

Phang, Tat Wai (2025) Comparative Bioactivities of Essential Oils from Kaffir Lime Peel Wastes and Bentong Ginger Rhizomes. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Essential oils (EOs) from kaffir lime (Citrus hystrix) peel and Bentong ginger (Zingiber officinale var. Bentong) rhizome possess valuable aromatic and bioactive properties. There is a growing interest in their potential applications in various industries, especially as a natural alternative ingredient to improve the biological performance and market value of other existing products. This study aimed to compare the phytochemical profiles, antioxidant, and anti-inflammatory activities of EOs from fresh kaffir lime peel and Bentong ginger rhizome. The EOs were extracted using the ultrasonication-assisted hydrodistillation method. Determination of total phenolic (TPC) and total flavonoid (TFC) contents along with GC-MS analysis were conducted to elucidate the chemical compounds present in both samples. Antioxidative evaluation included ferric reducing antioxidant power (FRAP), metal chelation, DPPH and ABTS radical scavenging assays, while bovine serum albumin (BSA) denaturation inhibition test was used to determine anti-inflammatory activities of the EOs extracted. Through GC-MS analysis, kaffir lime peel EO was found to contain β-Pinene (19.9%) and Citronellal (18.7%) as the major volatile compounds whilst Bentong ginger rhizome EO possessed α-Citral (22%), α-Curcumene (15.5%), and β-Citral (13%). Bentong ginger rhizome EO exhibited higher TPC and TFC, resulting in stronger antioxidant performances based on FRAP, DPPH and ABTS radical scavenging assays at concentrations 1 to 50 mg/mL. Kaffir lime peel EO, on the other hand, demonstrated stronger ferrous ion-chelating activity besides exerting superior anti-inflammatory properties as reflected by higher inhibitory effect towards BSA denaturation. This interesting phenomenon could be attributed to the presence of β-pinene in the kaffir lime peel EO. This volatile compound had displayed anti-inflammatory as well as metal chelating properties in previous studies. As such, kaffir lime peel, a food waste, may offer a more cost-effective and eco-friendlier raw material to produce EO with competitive bioactivities as compared to the high-priced Bentong ginger.