Rapid Solid-Liquid Dynamic Extraction (RSLDE): a New Rapid and Greener Method for Extracting Two Steviol Glycosides (Stevioside and Rebaudioside A) from Stevia Leaves.

Stevioside and rebaudioside A are the main diterpene glycosides present in the leaves of the Stevia rebaudiana plant, which is used in the production of foods and low-calorie beverages. The difficulties associated with their extraction and purification are currently a problem for the food processing industries. The objective of this study was to develop an effective and economically viable method to obtain a high-quality product while trying to overcome the disadvantages derived from the conventional transformation processes. For this reason, extractions were carried out using a conventional maceration (CM) and a cyclically pressurized extraction known as rapid solid-liquid dynamic extraction (RSLDE) by the Naviglio extractor (NE). After only 20 min of extraction using the NE, a quantity of rebaudioside A and stevioside equal to 1197.8 and 413.6 mg/L was obtained, respectively, while for the CM, the optimum time was 90 min. From the results, it can be stated that the extraction process by NE and its subsequent purification developed in this study is a simple, economical, environmentally friendly method for producing steviol glycosides. Therefore, this method constitutes a valid alternative to conventional extraction by reducing the extraction time and the consumption of toxic solvents and favouring the use of the extracted metabolites as food additives and/or nutraceuticals. As an added value and of local interest, the experiment was carried out on stevia leaves from the Benevento area (Italy), where a high content of rebaudioside A was observed, which exhibits a sweet taste compared to stevioside, which has a significant bitter aftertaste.

Characterization of Essential Oil Components from Aromatic Plants that Grow Wild in the "Piana del Sele" (Salerno, Southern Italy) using Gas Chromatography-Mass Spectrometry.

Essential oils from Rosmarinus officinalis, Salvia officinalis, Thymus vulgaris, Melissa officinalis and Mentha spicata growing wild in the "Piana del Sele" (Salerno, Southern Italy) have been extracted by hydro-distillation, quantified and characterized by gas chromatography coupled with flame ionization detection (FID) and mass-spectrometry (MS). Sixty-nine compounds were identified and classified according to their chemical classes. The results showed that the composition of the essential oils was extremely variable and specific for each botanical species. Hydrocarbons were the most abundant class in all essential oils except for sage where aldehydes and ketones were the most representative compounds. Only for thyme was a higher content of alcohols found.