Summary

Microbial growth in leather production is a significant problem that negatively affects product quality and economic value. Although conventional synthetic biocides are effective, their toxicity and environmental risks restrict both their application and permissible concentrations, and these limitations are expected to become more stringent in the future. In this context, plant-based essential oils have emerged as natural, biodegradable, and low-toxicity alternatives. Essential oils consist of complex chemical constituents, including mono- and sesquiterpenes, oxygenated derivatives, and aromatic compounds, and can be extracted from various plant organs using different methods. Numerous studies have demonstrated the antimicrobial, antifungal, and antibacterial activities of essential oils during various stages of leather processing, such as soaking, tanning, fatliquoring, and finishing. Essential oils including thyme, myrtle, frankincense, bay laurel, juniper, lavender, lemongrass, cinnamon, clove, and tea tree oil have been reported to effectively reduce fungal and bacterial growth in leather and leather products. Furthermore, nanoencapsulation and controlled-release strategies have been investigated to prolong the antimicrobial effectiveness of essential oils. In addition to their antimicrobial activity, essential oils exhibit antioxidant properties, suggesting further potential applications in other leather processing steps. The use of essential oils, either individually or in combination, is therefore considered a promising approach for developing sustainable, environmentally friendly, and safe biocidal systems in the leather industry.