Supercritical Fluid Extraction of Major Bioactive Flavonoids from Spearmint (Mentha Spicata L.) Leaves

Supercritical fluid extraction (SFE) is an attractive alternative technique to conventional liquid extraction due to its several distinct properties. This novel interesting extraction method which was developed in 1960 is an energy efficient, economically viable and environmentally friendly process. This study evaluated the effect of supercritical carbon dioxide extraction on the extraction yields and major bioactive flavonoid compounds from the herbal matrices. Two basic extraction methods were investigated: conventional soxhlet extraction (CSE) and supercritical carbon dioxide (SC-CO2) extraction. High-Performance Liquid Chromatography (HPLC) was used to identify and quantify bioactive flavonoid compounds of produced extracts. Results obtained from the two extraction methods were compared for a higher extraction yield and concentration of flavonoid compounds. In the study of supercritical carbon dioxide extraction and conventional soxhlet extraction spearmint (Mentha spicata L.) leaves were selected. For optimizing of SC-CO2 extraction process three most important variables including temperature, pressure and extraction dynamic time have been studied. The full factorial in complete randomize design (CRD) based on three levels and three factors was employed to obtain the optimum condition for SFE. Based on the simultaneous optimization of crude extract yield and concentration of flavonoid compounds the optimum condition was found at temperature of 60 ᵒC, pressure of 200 bar and extraction dynamic time of 60 min. In conventional soxhlet extraction study, different solvents were used to evaluate the effect of different applied solvents on the extraction yield and major bioactive flavonoid compounds. Ethanol: water (70:30) was found as a preferable solvent among the other applied solvents due to its higher extraction yield, flavonoid compounds concentration and lower toxicity effects. Compared with supercritical carbon dioxide extraction the higher concentration of bioactive flavonoid compounds was obtained and extraction time was reduced by applying SC-CO2 extraction. However, the higher crude extract yields were obtained by using conventional soxhlet extraction. The influence of co-solvent (modifier) on the extraction yield and extracted flavonoid compounds from spearmint (Mentha spicata L.) leaves was also studied. In this study ethanol acted as co-solvent to improve the efficiency of polar compounds (flavonoids) extraction. Co-solvent flow rate of 6 g/min was found as a preferable modifier flow rate to obtain higher extraction yield and bioactive flavonoid compounds concentration

Extraction of valuable compounds from winter melon (Benincasa hispida (thunb.) cogn.) seeds using ultrasonic-assisted solvent, supercritical carbon dioxide and pressure-swing methods

Different extraction techniques have been used to isolate valuable compounds from different plants. Conventional Soxhlet extraction (CSE) is a standard technique which has been used for a long time. The main disadvantages of conventional techniques are long extraction time which is not always accepted by industries. This extraction method is also not suitable for the extraction of thermo-sensitive compounds due to the possibility of thermal decomposition of target compounds as extraction usually occurs at the boiling point of used solvent for a long time. The current study presented the effect of various extraction methods including conventional Soxhlet extraction (CSE), ultrasound-assisted extraction (UAE),supercritical carbon dioxide (CO2) extraction (SCE) and SCE with pressure swing technique (SCE-PST) for extraction of valuable compounds from winter melon (Benincasa hispida (Thunb.) Cogn.) seeds. Parameters examined were crude extraction yield (CEY), radical scavenging activity (RSA) in terms of 1, 1-diphenyl 2-picrylhydrazyl (DPPH˙) radicals scavenging percentage (%DPPHsc) and 2,2´-Azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS+˙) radicals scavenging percentage (%ABTSsc) and total phenolic content (TPC) of B.hispida seeds. The overall optimum conditions for obtaining maximum dependent variables were predicted using response surface methodology (RSM). Under the optimised conditions, the fatty acid composition of extracts was identified and quantified using gas chromatography (GC). In CSE different solvents (n-hexane, ethanol and ethyl acetate) were used and the highest CEY (294.45 ± 1.22 mgg-1) obtained using ethyl acetate. Ethanol (EtOH) extracts showed the highest %DPPHsc and %ABTSsc (28.7 ± 0.7 and 27.0 ± 0.9, respectively) while n-hexane extracts possessed the lowest (13.1 ± 0.9 and 12.2 ± 0.6, respectively). TPC ranging from zero in n-hexane extract to 11.34 ± 1.3 mg GAE/g extracts obtained using EtOH which revealed the antioxidant potency of B. hispida seeds. In order to improve the quality and quantity of the extracts, UAE was applied and significant (p<0.05) effect of amplitude, temperature and sonication time was detected. The overall optimum conditions predicted to be 65% amplitude, 52 ºC and 35.00 min. under the optimum conditions the CEY, %DPPHsc, %ABTSsc and TPC were 108.50 mgg-1, 43.47%, 36.47% and 23.97 mg GAE/g extract. In the following,the SCE was investigated and it was found that studied parameters (pressure, temperature and dynamic extraction time) significantly (p<0.05) affected the dependent variables. The optimum conditions found to be 234.25 bar, 46 ºC and 95.05 min and under this optimum condition, the CEY, %DPPHsc, %ABTSsc and TPC were 174.91 mgg-1, 52.96%, 61.65% and 40.45 mg GAE/g extract,respectively. Finally, SCE-PST was investigated at different levels of pressure,holding time and continuous extraction time. The significant (p<0.05) difference in responses revealed the crucial and effective role of PST for improving the SCE process. The overall optimum conditions predicted to be 179.18 bar, 10.15 min holding time and 52.47 min continuous extraction time. Under the optimum condition the CEY, %DPPHsc, %ABTSsc and TPC were 235.12 mgg-1, 67.36%,64.42% and 42.77 mg GAE/g extract, respectively. Significant difference (p<0.05) for fatty acid composition was found between CSE and various extraction methods while considerable difference is not found between the unsaturated fatty acids (UFAs) content of extracts using UAE (82.00%), SCE (83.67%) and SCE-PST (84.34%). Generally, the dominant composition of the UFAs was linoleic acid (C18:02) and oleic acid (C18:01). This study, for the first time, confirmed the possibility of using UAE, SCE and SCE-PST to obtain the valuable extracts with high antioxidant potency and containing high amount of UFAs from B. hispida seeds

Antioxidant activity of spearmint (Mentha spicata L.) leaves extracts by supercritical carbon dioxide (SC-CO2) extraction

In this study, the effects of pressure (100–300 bar), temperature (40–60ºC) and co-solvent flow rate (3–9 g/min) on antioxidant activities of supercritical carbon dioxide (SC-CO²) extracts of spearmint leaves were determined using full factorial in the frame of complete randomize design (CRD). The antioxidant activity of SC-CO² extracts was determined by DPPH radical scavenging method. The results showed that extraction pressure, temperature and co-solvent flow rate had significant effect (P < 0.05) on antioxidant activity of extracts obtained. The highest antioxidant activity (71.00 ± 2.65%) was obtained at 200 bar pressure, 50ºC and 6 g/min co-solvent flow rate. However, all of the extracts obtained in this study had significantly higher antiradical activities varying from 35.62 ± 0.34% to 72 ± 3.17% compared to butylated hydroxytoluene (BHT) as a reference. These results indicated that supercritical carbon dioxide is a promising alternative process for recovering compounds of high antioxidant activities from spearmint leaves

Mathematical modelling of mass transfer during osmotic dehydration of seedless guava (Pisidium guajava L.) cubes

The present work aimed to study kinetics of osmotic dehydration of seedless guava in terms of solid gain and water loss, which was evaluated at three sucrose concentration levels (30, 40 and 50% w/w), three temperature levels of osmotic solution (30, 40 and 50°C) for 240 min. The experimental data was fitted to different empirical kinetic models including Peleg, Page and Azuara. Determination of coefficient (R 2 ), root mean square error (RMSE) and mean relative deviation modulus (E) were used for determination of the best suitable model. The present work shows that the Peleg empirical model satisfactorily described the dehydration kinetics with the highest R 2 ( > 0.95) and the lowest RMSE ( < 0.003) and E ( < 5.20%). Moreover, the effect of solution concentration and temperature was also studied and it was found that initial water loss and solid gain are related to solution concentration and temperature whereas equilibrium contents are related to sucrose concentration. From the experimental data it is possible to estimate the equilibrium content of water and solid

Ultrasound-assisted extraction of valuable compounds from winter melon (Benincasa hispida) seeds

Ultrasound-assisted extraction (UAE) was applied for the extraction of bioactive valuable compounds from winter melon (Benincasa hispida) seeds. Effects of amplitude (25-75%), temperature (40-60°C) and sonication time (20-60 min) on crude extraction yield (CEY) and radical scavenging activities (RSA, % inhibition of DPPH˙ and ABTS˙+ free radicals) of extracts were determined using complete randomised design (CRD). The results showed that the CEY and RSA of extracts significantly affected by independent variables. The maximum value of CEY (97.14±0.36 mgg-1), scavenging of DPPH˙ radicals (32.12 ± 0.38%) and scavenging of ABTS˙+ radicals (40.52±0.73%) were obtained at the combined treatment conditions of 75%, 55°C and 40 min. The UAE results obtained were compared with those achieved by using conventional Soxhlet extraction (CSE) method. It was found UAE allowed extraction at lower temperature and the extracts obtained posses higher quality compare with CSE. UAE is a promising environment friendly technique for the extraction of bioactive compounds from winter melon (Benincasa hispida) seeds

Modelling the kinetics of peroxidase inactivation and colour changes of seedless guava (Psidium guajava L.) during thermal treatments

The kinetics of thermal inactivation of peroxidase and colour changes in seedless guava (Psidium guajava L.) due to hot water blanching were studied in the temperature range of 80-95°C. Peroxidase inactivation kinetics followed a first-order Arrhenius model, where the activation energy and rate of the reaction at a reference temperature of 87.5°C were 101.27±3 kJ mol-1 and 0.023±4×10-3s-1, respectively. Colour was quantified using the L, a, b in Hunter system. The results indicated that colour system parameters (L, a, b) followed a first-order Arrhenius kinetics model with activation energies (Ea) of 120.43±3, 86.45±5 and a 100.03±2, kJmol-1, respectively. The zero-order kinetic model was applied to total colour difference (TCD) resulting in activation energies of 111.65±5 kJmol-1. Good agreement was found between estimated and experimental data in all cases (R2>0.91)

Modelling the kinetics of seedless guava(Psidium guajava L.) peroxidase inactivation due to heat and thermosonication treatments.

Effect of heat and thermosonication on inactivation kinetics of peroxidase in seedless guava have been studied over a temperature range of 80-95°C. Application of thermosonication was studied at 25, 50 and 75% of radiation intensity at the same temperature range. Ultrasonic wave’s intensity had significant(P<0.05) effect on peroxidase inactivation rate except the 25% intensity radiation. In both treatments, the enzyme kinetics showed a first-order kinetics model with monophasic behaviour. The activation energy, the rate constants were estimated which proving that the enzyme became more heat labile. Therefore, thermosonication can affect a process with reduced processing time and increased efficiency

Supercritical fluid extraction of bioactive flavonoid from Strobilanthes crispus (pecah kaca) and its comparison with solvent extraction

Supercritical carbon dioxide extraction (SC-CO 2) of bioactive flavonoid from Strobilanthes crispus (Pecah Kaca) was performed to study the effects of various parameters such as pressure, temperature and dynamic extraction time on the yield and composition of bioactive flavonoid. The results were also compared with those obtained by conventional Soxhlet extraction in lab conditions. The results from SFE showed that the effect of extraction variables on extraction yields decreased in the following order: pressure, temperature and dynamic extraction time. The extraction pressure played a dominant role in the yield of the sample while the effect of time could be ignored. This study also revealed that both Soxhlet extraction and SC-CO 2 extraction can be used to obtain flavonoid compound. Under the optimum conditions, the highest bioactive flavonoid compound content was obtained at 3.98% and eight flavonoid compounds were identified by HPLC

Supercritical carbon dioxide (SC-CO2) extraction of catechin, epicatechin, rutin and luteolin from spearmint (Mentha spicata L.) leaves

In this study, supercritical carbon dioxide (SC-CO2) extraction conditions were optimized for the simultaneous separation of four bioactive flavonoids (catechin, CA; epicatechin, EP; rutin, RU; luteolin, LU) contained in spearmint (Mentha spicata L.) leaves. SC-CO2 extraction parameters such as pressure, temperature and dynamic extraction time were optimized by Complete Randomize Design (CRD) full factorial. The optimum condition of SC-CO2 extraction was achieved at 200 bar, 60°C and 60 min (with 60.566 mg/g extraction yield). Extracted yield at optimum condition was then analyzed by high performance liquid chromatography (HPLC) for quantifying bioactive flavonoid compounds. At optimum conditions, four bioactive flavonoids including (+)-catechin, (-)-epicatechin, rutin and luteolin were detected at high concentration. Luteolin (0.657 mg/g) had the highest concentration among the other detected flavonoids. The results indicated that SC-CO2 extraction is a promising and alternative process for recovering the bioactive compounds from spearmint leaves

Characterization of valuable compounds from winter melon (Benincasa hispida (Thunb.) Cogn.) seeds using supercritical carbon dioxide extraction combined with pressure swing technique

In this study, we describe the extraction of different valuable compounds from winter melon seeds using supercritical carbon dioxide extraction combined with pressure swing technique (SCE-PST). The effects of the extraction variables, namely pressure, holding time (HT), and continuous extraction time (CT), were optimized by response surface methodology (RSM) to maximize the crude extraction yield (CEY). The optimal conditions were at pressure of 181.35 bar, HT of 9.93 min, and CT of 50.14 min. Under these conditions, the experimental CEY was 235.70 ± 0.11 mg g−1 with a relatively strong antioxidant activity (64.42 ± 0.21 % inhibition of DPPH· radicals, 67.36 ± 0.34 % inhibition of ABTS·+ radicals) and considerable amount of phenolic compounds (42.77 ± 0.40 mg gallic acid equivalent/g extract). The high-performance liquid chromatography (HPLC) analysis revealed that the bioactive phenolic compounds increased significantly using PST (p < 0.05), where gallic acid had the highest concentration (0.688 ± 0.34 mg g−1). The extract obtained using optimal SCE-PST conditions contained more than 83.65 % total unsaturated fatty acids (UFAs) and linoleic acid accounted for 67.33 ± 0.22 % in the total extract. From the results, the SCE efficiency in terms of extract quantity and quality has been enhanced significantly applying PST. Finally, the results were compared with previous published findings using supercritical carbon dioxide, ultrasound-assisted, and Soxhlet extraction. It was found that higher CEY could be achieved using Soxhlet extraction even through the quality of SCE-PST extracts in terms of antioxidant activity and phenolic compounds was better