Application of Chromatographic and Microbiological Analyses to Identify and Assess the Durability of Antimicrobial Properties of Innovative Materials for the Footwear Industry─Leather Modified with Origanum vulgare Oil

Abstract

A modification of the leather finishing technology in which the essential oil of Origanum vulgare is applied during the process of fatliquoring imparts antimicrobial activity to leather. This paper presents the characteristics of cowhide lining leather enriched with oregano oil (3%wt) in terms of durability of the antimicrobial activity conferred to it. Analyses carried out using gas chromatography–mass spectrometry have shown that carvacrol, the main component of oregano oil which is responsible for antiseptic action, constitutes more than 65% of the mixture of organic compounds detected in the vapor phase over samples of leather enriched with the oil even after 72 months of application. The results of an investigation into the kinetics of volatile compounds emission from leather samples treated with oil provided a proof that carvacrol emission decreased over time in an exponential way but did not fade out. This correlates with the results of microbiological analyses conducted using the agar plate diffusion method. The zones of growth inhibition obtained for the strains of microorganisms with sizes of 13 mm (Staphylococcus aureus), 1–3 mm (Candida albicans), and 2 mm (Staphylococcus epidermidis, Scopulariopsis brevicaulis) confirmed that the leather treated with oil still showed good activity against Gram-positive bacteria and fungi after 72 months of storage. The long-lasting antimicrobial properties of leather enriched with a natural biocide─oregano essential oil make it possible to be used in the production of special footwear intended for people with problems of the skin of the feet and toenails caused by pathogenic bacteria and fungi.