Comparative Analysis of Oil Extraction from Clove and Ginger using Maceration and Soxhlet Methods: Physicochemical Properties and Quality Assessment

Abstract

This study examined oil extraction from clove and ginger using two methods: Maceration method and Soxhlet extraction method. The materials (clove and ginger) were purchased locally from a credible vendor at Erekesan Market, Akure, Ondo State. The oils’ physicochemical properties analyzed included pH, color, specific gravity, impurity content, and moisture content. Additionally, the Free Fatty Acid (FFA) value, acid value, Thiobarbituric acid (TBA) value, saponification value, and FFA profile were assessed. The pH (4.52 - 6.08) and specific gravity (0.85 - 0.97) were well within the accepted range. The oils' hues deviated from those documented in prior studies, likely due to the elevated temperature exposure during extraction. The impurity content varied from acceptable (7.07%) to unacceptable (21.59%) for edible oils. The moisture contents (1.37 - 8.88%) indicate low susceptibility to microbial growth. The commercial ginger oil (control) exhibited the lowest FFA (5.51 g/100ml) and acid value (10.96 g/100ml), indicating better stability and resistance to rancidity while the clove oil (Soxhlet method) had the highest FFA (10.10 g/100ml) and acid value (20.10 g/100ml), therefore it has the least desirable quality. The oils’ TBA values (0.0024 - 0.0025 mgMDA/g) indicate enhanced stability and extended shelf life while their saponification value (80.15 - 196.08 mg/g), indicate varying but ideal FFA molecular weights. The oil samples showed diverse FFA profile: the higher ΣSFA composition (73.58%) of the commercial ginger oil (control) implies an undesirable quality as it has a higher risk of heart disease when consumed in large quantity while the ginger and clove samples extracted using maceration exhibited desirable ΣMUFA (22.99%) and ΣPUFA (22.78%) compositions. These affirm the influence of the extraction methods on the quality indices of the oils.  Based on the analyses conducted, it is concluded that the maceration extraction method is superior in producing higher-quality oils.