Life cycle assessment of green pilot-scale extraction processes to obtain potent antioxidants from rosemary leaves

J. of Supercritical Fluids 72 (2012) 205–212

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Life cycle assessment of green pilot-scale extraction processes to obtain potent antioxidants from rosemary leaves Irene Rodríguez-Meizoso a , María Castro-Puyana b , Pål Börjesson c , Jose A. Mendiola b , ˜ b,∗ Charlotta Turner a , Elena Ibánez a

Lund University, Department of Chemistry, Centre for Analysis and Synthesis, P.O. Box 124, SE-22 100 Lund, Sweden Institute of Food Science Research (CIAL-CSIC), Bioactivity and Food Analysis Department, Nicolás Cabrera 9, Campus UAM Cantoblanco, 28049 Madrid, Spain c Lund Institute of Technology, Environmental and Energy System Studies, P.O. Box 118, SE-221 00 Lund, Sweden b

a r t i c l e

i n f o

Article history: Received 13 July 2012 Received in revised form 20 September 2012 Accepted 22 September 2012 Keywords: Rosemary On-line process WEPO Life cycle assessment Pressurized hot water extraction SFE

a b s t r a c t In this work, the water extraction and particle formation on-line (WEPO) process has been used to obtain dry antioxidant powder from rosemary leaves. This process includes pressurized hot water extraction (PHWE) and on-line drying of the extracts in one step. Based on previous works, water extraction at 200 ◦ C was selected to achieve the maximum antioxidant activity while water flow rate was studied to determine its influence on powder formation. Other parameters influencing the drying process, such as scCO2 pressure (80 bar) and flow rate (2.5 mL/min) and N2 flow rate (0.6 mL/min) were settled to obtain a fine and constant spray. Powders obtained were evaluated in terms of particle size and morphology by scanning electron microscopy (SEM) as well as antioxidant capacity by an in vitro DPPH antioxidant assay. In order to assess the environmental performance of the WEPO process, this has been compared in terms of Life Cycle Assessment (LCA) to other green processes typically used for antioxidant extraction from rosemary leaves, such as supercritical fluid extraction (SFE) and a static pressurized hot water extraction, PHWE, carried out with a commercial equipment, both followed by a conventional drying step. The WEPO process, carried out in one step, giving dry bioactive extracts from rosemary, results in lower environmental impacts and energy consumption than the other green processes studied. The sensitivity assessment demonstrated the importance of primary energy sources in the production of electricity used, especially when green processes are being implemented. © 2012 Elsevier B.V. All rights reserved.

1. Introduction Rosemary has been extensively studied for its beneficial properties; activities such as antioxidant [1,2], antimicrobial [3,4], anticarcinogenic [5–7], among others, have been described. Antioxidant activity has been mainly attributed to the presence of phenolic diterpenes such as carnosic acid, carnosol, and rosmarinic acid [8–10]. In previous works, we stressed the importance of the extraction process in achieving the highest bioactivity and the most favorable chemical composition. Aspects such as a careful selection of the extraction process and optimization of the extraction conditions should be considered to selectively extract antioxidant compounds from rosemary. Among the different processes studied, pressurized hot water extraction (PHWE, also called subcritical water extraction, SWE, and pressurized liquid extraction, PLE, considering water as solvent for PLE) and supercritical fluid extraction (SFE) have been

∗ Corresponding author. Tel.: +34 910 017 956; fax: +34 910 017 905. ˜ E-mail address: elena@ifi.csic.es (E. Ibánez). 0896-8446/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.supflu.2012.09.005

recognized as the most selective and environmentally preferable techniques [11–18]. However, depending on the type of process and compounds of interest, either water or a polar organic solvent are needed and therefore, extracts obtained usually require a drying step (freeze or hot drying, depending on the type of solvent to be removed), which is both energy and time consuming; this fact has undoubtedly became the major limitation of the PHWE. One of the most promising ways to dry compounds from organic solutions is the use of particle formation processes based on supercritical fluids; these processes involve different solvent–antisolvent steps [19–22]; in the case of aqueous solution, these processes are not suitable for drying due to the low solubility of supercritical carbon dioxide (scCO2 ) in water. At present, only CAN-BD (Carbon dioxide Assisted Nebulisation-Bubble Dryer) and PGSS (Precipitation from Gas Saturated Solution) processes have been employed for aqueous solutions. For instance, CAN-BD has been applied to obtain powders from pure proteins [23,24], DNA and RNA [25], vaccines [26], antibiotics, antiviral [27], and other water soluble drugs [28], while PGSS has been used to dry more complex water solutions, such as green tea extracts [29].

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In 2009, we patented a new process combining PHWE plus particle formation on-line (WEPO, Water Extraction and Particle formation On-line) as a novel way to obtain dried complex extracts from rosemary leaves in one step [30]. Recently, the WEPO process has been described and studied for the production of antioxidant powders from fresh onion as well [31]. The motivation to develop a one-step process like WEPO was that it would be less time consuming than a two-step process, i.e., extraction plus freeze or hot-air drying of the water extract. At the same time, it would decrease the risk of degradation of bioactive compounds due to reduced exposure time to heat, light and/or oxygen. Intuitively, it seems reasonable to think that the WEPO process would also be beneficial in terms of energy consumption when compared to, e.g., freeze-drying and therefore a “greener” alternative compared to the two-step process. However, this kind of assumptions should not be made without a detailed study of the entire process chain. A tool for this kind of comparative studies is Life Cycle Assessment (LCA). LCA is a standardized methodology, according to ISO 14044 [32] for assessing the environmental impacts associated with a product, process or service, over its entire life cycle [33]. It is a suitable tool to quantify and characterize flows of materials and energy and different environmental effects connected to, e.g., new extraction processes [16]. A major limitation for an LCA study is the lack of data regarding the different processes to be compared. As an example, there is no data available in literature for the production of antioxidant onion extracts by SFE and PHWE. However, the authors have studied SFE and PHWE at different scales (analytical and pilot) for the extraction of valuable antioxidants from rosemary leaves. In this work, we present the WEPO process applied to rosemary leaves. At the same time, we present a comparison between WEPO and other “green extraction processes” namely SFE and the static PHWE [34] in terms of environmental impact of producing dry rosemary extracts using the different processes. The environmental performance of the different processes at pilot-scale has been assessed by life cycle assessment (LCA) considering a gate-to-gate perspective for obtaining the product (dry rosemary extract); thus, two processes (extraction + drying) have been considered for SFE and PHWE (freeze-drying for PHWE and vacuum drying for SFE). Even though SFE using scCO2 is generally considered a “greener” alternative to the use of organic solvents, this is the first time that the environmental performance of an SFE process is studied in terms of LCA.

2. Materials and methods 2.1. Samples and reagents Rosemary (Rosmarinus officinalis L.) sample, consisted of dried rosemary leaves obtained from Murciana de Herboristeria (Murcia, Spain). The leaves were collected during September and then dried by using a traditional method previously described [35]. Cryogenic grinding of the sample was performed under carbon dioxide. The size of the particle (between 500 and 1000 ␮m) was determined by passing the ground plant material through sieves of appropriate size. The whole sample was stored in amber flasks at −20 ◦ C until use. 1,1-Diphenyl-2-picrylhydrazyl (DPPH, 95% purity) was from Sigma–Aldrich (Madrid, Spain). Methanol was HPLC grade from Lab Scan (Dublin, Ireland) and ethanol (99.5%) was from Panreac (Spain). Milli-Q water was obtained using a purification system (Millipore Corporation, Billerica, MA, USA) and deoxygenated in an ultrasound bath for 15 min before its use. CO2 (N38 quality) and N2 (Technical quality) were obtained from Praxair (Madrid, Spain). Anti-return and micrometric regulation valves were

purchased from Swagelok (OH, USA), while on/off valves were from Scientific Systems Inc. (PA, USA). 2.2. Equipment description Fig. 1 shows a scheme of the home-built equipment to carry out the water extraction and particle formation on-line process (WEPO). This equipment combines two processes: the continuous extraction of rosemary leaves using PHWE and the continuous production of an aerosol from the extract assisted by a supercritical CO2 nebulization system, which is instantaneously dried by a hot N2 current. Thus, the extraction and precipitation takes place in the same system with a small time delay between these two processes. While the WEPO set-up is fundamentally the same as previously described [31], it differs in the pieces of equipment used and is therefore described in this work. Water was pumped by using a modified Suprex Modifier pump; while a modified Suprex PrepMaster (Suprex, Pittsburgh, PA, USA) extractor was used to pump the CO2 . All the tubings were 316L stainless steel 1/16 in., except for the N2 tube (1/8 in.). The extraction cell and the tubings were placed inside an oven (Carlo Erba Strumentazione, Milan, Italy). The length of the tubing was selected to ensure enough time for the fluids to reach the desired temperature inside the oven. The extraction cell was placed inside the oven for temperature control. The tubing, containing the aqueous extract coming from the extraction cell, together with the micrometering valve (V1) (model SS-SS1, Swagelok, OH, USA), acting as restrictor, and the low dead volume tee fitting (Valco model JR-ZT1C, 0.25 mm bore, VICI AG International, Schenkon, Switzerland) were heated by using a heating tape (JP Selecta, Barcelona, Spain). For simplicity, the device used as an expansion and drying chamber was built on polypropylene with an internal volume of 1 L. Two entrances were built at the top of the expansion-drying chamber, one for the mixture extractCO2 coming from the tee fitting and another one for the hot N2 . The bottom of the chamber was closed with a cellulose paper filter (2.5 ␮m pore diameter, ashless 42, Whatman) to let gases (CO2 , N2 and water vapour) go out. Nitrogen temperature was kept above 70 ◦ C to avoid water condensation onto the walls. 2.3. Experimental procedure of WEPO The extraction cell was filled with a mixture of rosemary leaves (1 g) plus washed sea sand (2 g) to avoid system clogging. The process starts by filling the cell with water at a flow rate of 0.5 mL/min at room temperature. Then the water flow is stopped and the CO2 flow and the heating systems (oven and heating tape) are started. When the conditions are reached (80 bar and 2–3 mL/min for the CO2 , 200 ◦ C for the oven), N2 flow (at a pressure of 6–7 bar) is started and water is pumped in continuous flow through the extraction cell at a chosen flow rate (from 0.1 to 0.3 mL/min). The water extract is mixed under pressure with the supercritical CO2 in a low dead volume tee fitting, forming a gas expanded liquid [36] that flows through a restrictor and reaches the expansiondrying chamber. It is very important that the dead volume of the tee fitting is near zero to avoid expansion of the mixture inside the fitting. In the expansion-drying chamber, the pressure is below the critical point of the CO2 , so the solution is rapidly expanded because the CO2 becomes a gas. The aerosol formed in the expansion-drying chamber is dried by the hot N2 current. After the selected extraction time (40 min), valve V1 is closed and the water flow is stopped while CO2 and N2 flows continue for 10 more minutes. Thus, the entrance of extract droplets in the expansion-drying chamber due to a possible residual pressure in the extract line is avoided. Particles are collected from the walls of the expansion-drying chamber.

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Fig. 1. Scheme of the WEPO equipment.

2.4. Antioxidant capacity analysis The antioxidant capacity of the different extracts was determined by the DPPH radicals capture method, by using the following procedure [37]: 23.5 mg of DPPH were dissolved in 100 mL of methanol. This stock solution was diluted 1:10 with methanol. Then 0.1 mL of rosemary extracts at different concentrations and 3.9 mL of DPPH diluted solution were placed in test tubes to complete the final reaction media (4.0 mL). Reaction was completed after 4 h at room temperature and absorbance was measured at 516 nm in a UV/VIS Lambda 2 Perkin Elmer Inc. spectrophotometer (Wellesley, MA, USA). Methanol was used to adjust zero and DPPH–methanol solution as a reference sample. The DPPH concentration in the reaction medium was calculated from a calibration curve determined by linear regression. The percentage of remaining DPPH against the extract concentration was then plotted to obtain the amount of antioxidant necessary to decrease the initial DPPH concentration by 50% or EC50 . 2.5. Scanning electron microscopy (SEM) Particles were coated with a 4 nm gold layer by a sputter coater (Polaron, mod. SC7640) and analyzed by scanning electron microscopy (SEM) (Phillips, mod. XL30). 2.6. Life cycle assessment (LCA) The SimaPro software PRé 7.3 was used to perform LCA calculations [38]. Thus, the environmental performance of SFE, PHWE and WEPO processes were compared. To be able to make this comparison between the three techniques, their optimum conditions to provide rosemary extracts with similar antioxidant activities have been considered; that is, with antioxidant activities, measured as

EC50 values by DPPH radical scavenging assay, ranging from 6 to 10 ␮g/mL. The functional unit (FU) to which the environmental impact categories are normalized is here defined as 10 g rosemary extract having an equivalent antioxidant activity. The experimental conditions to obtain dry bioactive extracts from rosemary leaves by WEPO are set up in this work, whereas data on extraction conditions and bioactivities of rosemary extracts obtained by using static PHWE and SFE were taken from a previous work [34]. The key inventory data along with the database sources [39–41] for the three extraction processes at pilot-scale are shown in Table 1. Besides, Fig. 2 depicts the flowchart of the different steps necessary to obtain the rosemary extract by the three processes, as well as the technical system boundaries (dotted boxed) considered in the LCA analysis. In this gate-to-gate approach, the upstream and downstream steps linked to the extraction stage are not included. The downstream use and waste handling were assumed to be identical for all the processes studied, whereas the differences in the amount of raw material utilized was estimated to have a minor impact on the overall environmental performance. However, it should be borne in mind that a PLE with water will not be jeopardized by the presence of water in the raw material, but that water should be avoided for an optimal SFE process. The energy consumption of each component employed in the extraction process (oven, pump, freezer, freeze dryer, rotavapor) was calculated based on their specification (for commercial equipment) and uptime. The geographical system boundaries include Spain, Sweden and Germany having different electricity production systems. Considering the input of materials, average data for Europe are used. The characterization method used in the study was CML 2 baseline 2000 V2.05, available in the SimaPro software, which include the following impact categories: abiotic depletion, acidification, eutrophication, global warming 100 years (sometimes also referred to as carbon footprint), ozone layer depletion, human toxicity, fresh

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Table 1 Key inventory data for production of 10 g of rosemary extracts by PHWE, SFE and WEPO processes. PHWE

SFE

WEPO

Data source

Inputs From nature Rosemary leaves From technosphere Water Nitrogen Carbon dioxide Ethanol Electricity

475 g 1.2 kg – – 107 kWh

– – 277a g 19.4a g 39.1 kWh

382 g 48.5 g 353 g – 29.4 kWh

Ecoinvent ELCD Ecoinvent Ecoinvent Ecoinvent

Outputs Emissions to air Water Nitrogen Carbon dioxide

– – –

– – 277a g

382 g 48.5 g 353 g

– – –

Waste to treatment Solid waste Waste water Solvents mixture

16.4 g 475 g –

144 g – 19.4a g

19.4 g – –

Ecoinvent LCA Food DK Ecoinvent

26.4 g

154 g

29.4 g

–

a The amounts of CO2 and ethanol corresponded with the net value used taking into account a recycling of 95%.and a loss of 5% from the initial amounts (5.5 kg and 388 g of CO2 and ethanol respectively that corresponded to the amount of CO2 and ethanol needed to fill out the system).

Fig. 2. Flowchart of extraction processes to obtain antioxidants from rosemary leaves. (A) PHWE, (B) SFE, and (C) WEPO.

water aquatic ecotoxicity, marine aquatic ecotoxicity, terrestrial ecotoxicity, and photochemical oxidation.

3. Results and discussion 3.1. WEPO process set-up and particle characterization As mentioned, the WEPO process (dynamic PHWE and particle formation on-line) was applied to rosemary leaves using a homebuilt system (Fig. 1), as described in the experimental section. The main complexity in the development of on-line systems is that the best parameter values for each separate process might differ and these influence and limit each other in the hyphenation. In our case, the temperature of the experiments (200 ◦ C) was chosen according to the best extraction conditions. This temperature was selected based on previous works from our research group, since it enables to extract the maximum amount of carnosic acid, and therefore to obtain the maximum antioxidant activity, from

rosemary [42]. It is important to consider that during drying of the sample, very volatile compounds can be lost; since these compounds are not likely to contribute to the antioxidant activity of the final extract, we can be certain that all antioxidant compounds extracted will precipitate in the expansion-drying chamber. Thus, the selectivity of the process toward antioxidant compounds will be determined by the selectivity of the extraction process. If selectivity is combined with an appropriate drying process, it will be possible to achieve dry particles enriched in the compound(s) of interest. Since the same oven was used to heat all the tubings, CO2 and N2 temperatures were 200 ◦ C as well. The entrance of these hot currents inside the expansion-drying chamber provides a temperature of 70 ◦ C in the expansion-drying chamber. The CO2 pressure was set at 80 bar to ensure that the CO2 is in its supercritical state (above 74 bar and 31 ◦ C). Other parameters like N2 and CO2 flow rates (0.6 and 2.5 mL/min respectively) were also selected in order to obtain a proper aerosol from the tip of the restrictor that reaches the expansion-drying chamber; these parameters were modified

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Fig. 3. Rosemary particles observed by SEM, obtained at: (A) 0.1 mL/min, (B) 0.2 mL/min, and (C) 0.3 mL/min water flow rates.

considering the experimental settings available (the working range of the set up) and the spray formation was visually evaluated. The parameters chosen made it possible to carry out the process with three different water flow rates, 0.1, 0.2, and 0.3 mL/min. The whole process is taking place under mild conditions of light and in absence of oxygen; therefore, it is expected to obtain particles with intact biological activities. Under the optimum (and perfectly controlled) conditions in terms of pressure and N2 , CO2 , and water flow rate, a high extraction yield (34%, expressed as g of the extract per 100 g of rosemary) was obtained using an extraction time of 40 min. Moreover, the yield might be improved with further optimization of process parameters like expansion-drying chamber’s temperature and design, N2 flow rate and CO2 pressure and flow rate as well as those related to the extract viscosity such as extract concentration and composition [43]. Dried powders obtained were characterized in terms of their size, morphology and bioactivity (antioxidant properties). Regarding antioxidant capacity of the particles, EC50 values obtained were around 10.5 ␮g/mL in all the conditions tested. The antioxidant capacity values for rosemary are comparable to those obtained with a commercial PHWE extractor plus a freeze-drying process [34,42], but it is important to remark that commercial PHWE extractors only work in static extraction mode. On the other hand, Fig. 3 shows representative SEM images of the particles obtained from the WEPO process. The size of the particles and agglomerates can influence the solubility of the sample in different food matrices and its bioavailability. As can be observed, particles precipitate in agglomerates formed by smaller particles with no defined shape. Even though it is not possible to draw any conclusion about the relation between water flow rate and particle size, however, it is possible to see differences in the agglomeration degree and the size of the average particles, thus suggesting the possibility of tuning these properties with further process optimization. If we compare the WEPO process with spray-drying, and according to literature [43,44], conditions that enable fast drying processes may lead to bigger particles than those that enable slower drying, therefore N2 and CO2 flow rates, as well as the temperature of the expansion-drying chamber can be used to tune the particle size and morphology. The higher the liquid viscosity, the larger the droplets formed during atomization and thus, the larger the particles obtained by in the drying step [45]. As can be observed in Fig. 3, microparticles are collected as a fine powder with particle sizes less than 93 ␮m in diameter. Their small size could favor their solubility in different food matrices and/or its bioavailability in the intestine [46]. 3.2. Comparative life cycle assessment Once the WEPO process was set-up, its environmental impacts were compared with other green processes such as SFE and

commercial PHWE. The comparison was done for the production at pilot-scale of 10 g of dry rosemary extract with similar antioxidant capacity, thus this corresponds to the functional unit used in the LCA. For SFE and commercial PHWE processes, a drying step has been included in the evaluation, as it can be observed in Fig. 2. The selected drying method was the one that kept unaltered the antioxidant activity of extracts, namely: vacuum drying for SFE and freeze-drying for PHWE. Solid and liquid disposal were also considered in the forms they are produced and includes subsequent treatment methods, i.e., composting, incineration, wastewater treatment, and correlated emissions (see Fig. 2). Fig. 4 and Table 2 show the environmental impacts in the categories included for the three analyzed extraction processes (SFE, PHWE, and WEPO). In Fig. 4, bars have been normalized considering PHWE process as 100%. As it can be seen, the WEPO process provided the lowest environmental impacts in all the categories, being around 28% of the impacts caused by PHWE. The corresponding impact by the SFE process is around 37%. The main impacting category in all processes was marine aquatic ecotoxicity (see Table 2), which refers to the impact of toxic substances emitted to seas and/or oceans. Even if the values reached in this category seem to be very high it is important to emphasize that 1,4-DB has a NOAEL (No Observed Adverse Effect Level) in humans of 301 mg/m3 [47] and that the values reached in marine aquatic ecotoxicity category would be approximately the same that emitting 1 kg of DDT or cadmium (1 kg of DDT or cadmium are equivalent to 1.87 × 105 or 2.33 × 105 kg 1,4-DB respectively). By analyzing all the categories, it is clear that extraction solvents have no important impact mainly because they are green solvents (water for PHWE and WEPO, and CO2 + ethanol for SFE) and they are used in very low volumes. On the contrary, electricity production demonstrated to be the key factor due to its high significance in all the environmental impact categories studied. In fact, this factor contributes with values higher that 96% (mainly from 96.3% (human toxicity) to 99.7% (terrestrial ecotoxicity)) to the total environmental impact of each category. Even those processes using CO2 (SFE and WEPO), which contribute to the global warming potential, are more influenced by the amount of CO2 from the production of electricity needed than on the amount of CO2 used for the extraction of antioxidant rosemary extract. In the three extraction processes considered, electricity is used in heating and pumping and these operations should be optimized for a future scaling up by substituting electrical heating by other means of heating, for instance, direct natural gas burning. On the other hand, the greatest environmental impact was due to freeze-drying, whose energy source is not easy to substitute. Taking into account these results, the WEPO process could be outlined as a more environmentally preferable way to obtain high quality antioxidants from natural origin compared to other wellestablished green production ways. Considering the large impact of electricity, a sensitivity assessment of the LCA was carried out to study the different

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Fig. 4. Impact assessment comparison of 10 g of rosemary extract (FU) by SFE, WEPO, and PHWE. Normalized values respect to PHWE + freeze-drying, real values taken from Table 2 (1,4-DB: 1,4 dichlorobenzene; CFC-11: trichlorofluoromethane).

Table 2 Impact assessment to obtain 10 g of rosemary extract (FU) by PHWE, WEPO and SWE in Spain, Sweden and Germany. SPAIN Impact category Abiotic depletion (kg Sb equiv.) Acidification (kg SO2 equiv.) Eutrophication (kg PO4 equiv.) Global warming (kg CO2 equiv.) Ozone layer depletion (g CFC-11 equiv.) Human toxicity (kg 1,4-DB equiv.) Fresh water aquatic ecotox. (kg 1,4-DB equiv.) Marine aquatic ecotoxicity (kg 1,4-DB equiv.) Terrestrial ecotoxicity (kg 1,4-DB equiv.) Photochemical oxidation (kg C2 H4 )

SFE 0.17 0.22 0.05 23.64 1.3E−6 12.46 7.62 1.7E4 0.41 0.01

SWEDEN WEPO 0.13 0.17 0.03 18.03 1.0E−6 9.53 5.77 1.3E4 0.31 0.01

PHWE 0.46 0.60 0.12 63.89 3.5E−6 33.57 20.78 4.8E4 1.12 0.02

environmental impacts among the processes in different countries (Spain, Sweden, and Germany) since the effect of moving the facility to another country could modify the results. The comparison of the environmental impact of SFE, PHWE and WEPO per functional unit (10 g of dry rosemary extract with equivalent antioxidant capacity) is presented in Table 2. As can be seen, the lowest environmental impacts in all the categories were obtained for the WEPO and SFE processes, independently of the country. On the other hand, the production of the rosemary extract by the WEPO process in Sweden benefits from a lower impact of the electricity in all the categories, so that the environmental impact of the whole

SFE 0.03 0.02 0.01 4.50 0.5E−6 8.30 2.57 5.9E3 0.37 0.001

GERMANY WEPO 0.02 0.01 0.01 3.61 0.4E−6 6.39 1.97 4.5E3 0.28 0.001

PHWE 0.07 0.05 0.03 11.29 1.4E−6 22.13 6.92 16E3 1.01 0.002

SFE 0.21 0.04 0.11 28.53 1.1E−6 16.58 18.34 3.9E4 0.39 0.002

WEPO 0.16 0.03 0.09 21.72 0.8E−6 12.63 13.85 2.9E4 0.29 0.002

PHWE 0.57 0.12 0.31 77.34 3.0E−6 44.88 50.24 10.7E4 1.07 0.01

process is clearly decreased if is carried out in Sweden instead of in Spain or Germany, as shown in Fig. 5. As seen previously, electricity production is the main cause of environmental impacts in the described processes. The different values seen in Fig. 5 are strongly related with the primary energy sources used for electricity generation in each country, which is shown in Table 3. As can be seen, in every category, the Swedish energy production sources provide lower impacts due to the high production of energy from renewable sources [48] while in Spain and Germany the high weight of fossil fuel burning (lignite, hard coal, etc.) resulted in higher values.

Table 3 Percentages of primary energy sources in electricity production in Spain, Sweden and Germany.

Spain Sweden Germany

Hard coal

Lignite

Oil

Gas

Nuclear

Other

Renewable

12 – 7

– 1 29

0 – 4

0 – 9

46 45 27

2 1 2

40 53 22

Data taken from Eurostat [48].

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Fig. 5. Difference per impact category when comparing the production of 10 g of rosemary extract (FU) by WEPO in three different countries. Bars were normalized considering as 100% the maximum value achieved in each category.

4. Conclusions The WEPO process described in this work can be considered a suitable and promising process to obtain, in only one step, fine and dried powder with intact antioxidant capacity, directly from the plant leaves. Besides, the gate-to-gate LCA provided a comprehensive view of the environmental performance of the three green extraction processes compared in this work (SFE + vacuum drying, PHWE + freeze-drying and WEPO), demonstrating that the lowest environmental impacts in all the categories are achieved using the WEPO process set-up in this work. The sensitivity assessment demonstrated the importance of primary energy sources in the production of electricity used especially when a green process, like this, is being implemented.

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This work was supported by AGL2011-29857-C03-01 (Ministerio Ciencia e Innovación) and CSD2007-00063 FUN-CFOOD (Programa CONSOLIDER-INGENIO 2010) projects and one project of the Comunidad Autónoma de Madrid (S-0505/AGR/000153). C.T. acknowledges the Swedish Research Council FORMAS (2292009-1527); the Swedish Research Council (VR, 2006-4084, 2010-333); and the Swedish Foundation for Strategic Research (SSF, RMA08-0044). M.C.-P. thanks the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (JCI-2009-05297). References [1] M.E. Cuvelier, H. Richard, C. Berset, Antioxidative activity and phenolic composition of pilot-plant and commercial extracts of sage and rosemary, Journal of the American Oil Chemists’ Society 73 (1996) 645–652. [2] K.W. Quirin, SFE of natural antioxidants from rosemary and sage, Innovations in Food Technology 18 (2003) 186–191. [3] O.Y. Celiktas, E.E.H. Kocabas, E. Bedir, F.V. Sukan, T. Ozek, K.H.C. Baser, Antimicrobial activities of methanol extracts and essential oils of Rosmarinus officinalis,

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