## 3 Extractions Processes  
### RA Extraction  
Together with plant conservation after harvesting, the extraction process is the most critical step for obtaining significant amounts of biologically active polyphenolic compounds. The method of choice is driven by the stability and solubility of the compounds of interest, as well as by the desired scalability of the entire process. Traditional methods are based on the extraction of the compounds after the diffusion of a solvent in the plant matrix, and comprise maceration, infusion, heat reflux (HRE), and Soxhlet extraction. Due to its chemical structure, RA is conventionally extracted by methanol, acetone, ethanol, water, or a mixture of them. A percentage of water from 10 up to 70% is required for an efficient extraction of polyphenolic compounds as it could increase the diffusion of polyphenols from plant cells through the swelling effect on the plant tissues. More sophisticated techniques have been introduced with the aim of reducing solvent consumption and avoiding unnecessary losses of energy and time, thus reducing the overall cost of the procedure and its environmental impact. Among the most modern methods, supercritical fluid extraction, pressurized liquid extraction, and ultrasound-assisted (UAE) and microwave-assisted extraction (MAE) can be numbered. Numerous papers regarding the extraction of RA have been recently reviewed by [PERSON] et al. [77]. Here, we will discuss those papers reporting the direct comparison among different extraction techniques. In the following studies, the extraction yield (i.e., extracted mass vs. sample mass) and in some cases the extraction selectivity, were taken into consideration as main parameters to be optimized during the extraction process. [PERSON] and coworkers [78] compared the performances of six different configurations of ultrasound (bath, reactor, and probe) and microwave (reflux under microwave, microwave under nitrogen pressure and microwave under vapor pressure) based processes for the extraction of rosmarinic, carnisc and unsolic acids from rosmear. All processes used a mixture of ethanol/water (90/10, \(v/v\)), and the results (in terms of extraction yield, purity, and content in each of compound) were compared to conventional HRE and maceration. Extraction temperature was set at 78 \({}^{\circ}\)C, room temperature, 40 \({}^{\circ}\)C and 70 \({}^{\circ}\)C (or higher) for HRE, maceration, UAE, and MAE, respectively, and time was fixed at 30 min. The lowest total extraction yields were obtained with maceration and ultrasounds, which the authors attributed to temperature difference during extraction. MAE at 150 \({}^{\circ}\)C gave the highest total yield, but looking at the single compounds, RA was extracted in lower amounts with respect to carnisc and unsolic acid. The authors attributed this result to the extraction solvent, since RA is more soluble in water, whereas the other two compounds are more soluble in ethanol. The most suitable extraction methods for RA are confirmed as MAE at 125 \({}^{\circ}\)C or 150 \({}^{\circ}\)C, or conventional HRE extended up to 5 h, which indicates also that RA is not a thermo-sensitive compound. However, in terms of energy consumption and carbon emission, HRE prolonged for 5 h showed the highest energy-consumption (850 kWh/kg extract) and carbon emission (680 kg CO\({}_{2}\)/kg extract). In a similar study conducted in 2014 [79] on _R. officinalis_ leaves, different alkanol/aqueous mixtures in combination with Soxhlet extraction, MAE and UAE were evaluated. Different ultrasounds and microwaves operating conditions were studied. Both MAE and UAE were able to provide a three- and two-fold enhancement, respectively, with respect to hot percolation. Curiously, MAE provided the best result with 70% aqueous ethanol, while UAE yield was optimal with 70% aqueous methanol. [PERSON] et al.