Comparative Characterization of Lipid Composition and Minor Components in Coffee Oils from Arabica and Robusta Spent Coffee Grounds

Coffee oil, an increasingly recognized yet underutilized byproduct of spent coffee grounds, has attracted attention due to its diverse lipid composition and minor components. This study systematically investigated the lipid characteristics of coffee oils extracted from both Arabica and Robusta spent coffee grounds subjected to varying roasting degrees. Comprehensive analyses were conducted, mainly regarding oil yield, acid and peroxide values, fatty acid profiles, sn-2 positional fatty acid distribution, triacylglycerol composition, tocopherol content and total Folin-reactive compounds, as well as squalene and sterol profiles. The selected Arabica samples generally showed higher oil yields than Robusta samples, with oil contents ranging from 12.13% to 15.14% and 10.10% to 13.01%, respectively. Arabica coffee oils showed relatively high total tocopherol levels, ranging from 930.35 to 1495.37 mg/kg, whereas Robusta coffee oils ranged from 637.69 to 867.21 mg/kg. Total Folin-reactive compounds varied among samples and should be interpreted as composition-related indicators rather than direct evidence of antioxidant function. In contrast, Robusta coffee oils contained much higher levels of squalene and total sterols, ranging from 97.00 to 170.37 mg/100 g and 787.29 to 1007.92 mg/100 g, respectively. Chemometric analyses showed distinct grouping patterns among the selected coffee oil samples. In the present sample set, the overall lipid profiles were more closely associated with the Arabica and Robusta sample groups than with the assigned roasting levels. These results provide compositional information for the potential use of Arabica coffee oil as a tocopherol- and Folin-reactive compound-rich lipid ingredient. Robusta coffee oil may be further evaluated for applications requiring higher levels of squalene, phytosterols, and relatively saturated lipid structures. This study provides novel insights into the compositional complexity of coffee oil and supports its targeted valorization across various industries.