Effects of Enzymatic Pretreatment on Yield and Volatile Composition of Citrus Peel Essential Oils

Enzymatic pretreatment is a promising method for modulating essential oil isolation. This study evaluated the effects of pectinase, cellulase, xylanase, and their mixture, applied in purified water or citrate buffer before Clevenger hydrodistillation, on the yield and volatile composition of essential oils from orange, mandarin, and clementine peels. Essential oil yield increased slightly for orange and mandarin peels (up to approximately 2%) compared to non-enzymatic controls, while clementine yield was unaffected. Limonene remained the dominant compound in all oils, reaching 81.16% in orange, 77.50% in mandarin, and 75.29% in clementine. Enzyme pretreatment particularly affected the secondary components: mandarin peel showed increased sesquiterpenes (up to 60.52%) and aldehydes (up to 4.86%), while clementine oils exhibited higher oxygenated monoterpenes after buffer-based enzymatic treatments. These results indicate that enzyme-assisted pretreatment can modulate the volatile profile of citrus essential oils, although overall yield gains are modest. The inclusion of no-enzyme and no-pretreatment controls is crucial for the reliable assessment of enzymatic effects under laboratory conditions. This systematic approach provides insight into enzyme-assisted extraction, highlighting its potential to influence essential oil quality and composition rather than dramatically increase yield, and offers a foundation for further optimization research.