Drying modulates volatile composition and enhances antimicrobial activity of essential oils from Campomanesia adamantium fruit-processing residues: a chemometric study

Abstract

C. adamantium (Cambess.) O. Berg (Myrtaceae), commonly known as guavira, is a Cerrado species of high bioeconomic value whose fruit-processing residues represent a promising source of bioactive essential oils. However, the influence of drying conditions on the yield, composition, and antibacterial activity of these oils remains poorly understood. Therefore, this study integrated GC–MS-based chemical profiling with multivariate chemometric analyses to investigate drying-induced changes in essential oils obtained from Campomanesia adamantium peels and seeds. Peels and seeds were subjected to two drying treatments: oven drying at 40 °C and room-temperature drying (RT, ∼22 °C). Essential oils were obtained by hydrodistillation after 1, 2, 4, 6, and 8 days of drying, using fresh residues as control (day 0). Chemical composition was characterized by GC–MS. Chemometric analyses, including PLS-DA, HCA, and heatmap visualization, were applied to evaluate drying-induced chemical alterations. Antimicrobial activity against a β-lactamase-producing Staphylococcus aureus strain was assessed by minimum inhibitory concentration (MIC). Drying significantly affected essential oil yield, composition, and antibacterial activity. Oven drying increased essential oil yield from 0.105% ± 0.015% in fresh residues to 0.276% ± 0.037% after drying, representing a 2.63-fold increase. The major compounds identified were limonene and β-pinene, whereas 1,8-cineole, absent in fresh samples, became abundant after drying. Heatmap and PLS-DA analyses demonstrated clear discrimination among treatments, revealing reduction of hydrocarbon monoterpenes and increased relative abundance of oxygenated compounds after drying. Room-temperature drying maintained a volatile profile closer to that of the fresh essential oil, whereas oven drying induced more pronounced compositional changes. Antimicrobial assays demonstrated marked enhancement of antibacterial activity after drying. Fresh samples exhibited MIC values ≥2000 μg mL -1 , whereas room temperature dried samples at 6 and 8 days showed the strongest activity, with MIC values of 7.5 μg mL -1 against S. aureus . Controlled drying effectively enhanced the value of C. adamantium fruit-processing residues by improving essential oil recovery and antibacterial activity while modulating volatile composition. The improved stability of the dried plant material also facilitates storage and transportation, supporting its sustainable use as a raw material for pharmaceutical, cosmetic, and food applications.