Comparison of Oven and Microwave Drying on Extraction of Spent Coffee Grounds Oil

Spent coffee grounds (SCG) are frequently disposed of in landfills, which creates significant environmental concerns. Scientists are investigating methods to repurpose SCG, recognizing its potential for various beneficial applications. This study compared oven and microwave drying methods for extracting oil from spent coffee grounds (SCG), focusing on yield and quality of oil. The findings demonstrated that oven drying resulted in a slightly lower moisture content and a significantly higher oil yield (10.01%) compared to microwave drying (8.9%). Additionally, oil from oven-dried SCG exhibited superior quality, with lower acid and peroxide values, indicating less oxidative degradation during the drying process. The structural analysis further supported these results, showing that oven drying better preserved the SCG's cellular structure, which may contribute to the higher retention of oil-bearing compounds. In contrast, microwave drying, while faster, caused more structural damage and led to lower oil yield and reduced quality due to its rapid heating mechanism. This research contributes to the growing body of knowledge on sustainable SCG utilization by highlighting the advantages of oven drying for optimizing oil extraction. The findings are particularly relevant for industries that prioritize oil quality and yield, such as cosmetics and pharmaceuticals.