Cultivation techniques and drying process can affect the inflorescence essential oil composition of three selections of Salvia officinalis

Salvia officinalis is commonly used as an ingredient in the food industry and has been shown to possess several biological activities. The essential oil (EO) of S. officinalis is characterized by thujones compounds, which are subjected to certain limits in the European Union (EU), as food additive. Sage inflorescences have different profile compared to leaves, with lower content in thujones, and could be exploited in the food sector. The yield of S. officinalis inflorescence can be affected by various cultural techniques, while postharvest management of the raw material could affect the EO quality, depending on whether it is extracted from fresh or dried inflorescences. In this regard, studying the factors which have a role in the EO quality and quantity is necessary. A 2-year study has been conducted to compare inflorescences and oil yield of three sage selections (S. officinalis; S. officinalis subsp. lavandulifolia; and S. officinalis ‘Extrakta’), at two plant densities (4.76 plants/m²; 2.86 plants/m²), and two weed control techniques (manual vs. mulching). After harvest, the additional effect of two postharvest management systems (EO from fresh herbs; EO from 50 °C oven-dried herbs) on the EO quality was assessed too. All the tested selections synthesised low thujone contents in the inflorescences. The study showed that the plants age can influence the EO profile, while genetic can interact with some cultural techniques, leading to an increase in the EO content, and to the EO profile modification. The drying process changed the EO composition according to the drying temperatures. In specific, the oven-drying temperature of 50 °C reduced the EO content by 75%, according to the used chemical compound. Furthermore, the results showed that 50 °C, the most commercial temperature used for drying herbs, is less suitable to preserve the terpene fraction of the EO of sage inflorescences, suggesting that either lower temperatures or other drying methods should be recommended.