Influence of ultrasonic amplitude,temperature, time and solvent concentration on bioactive compounds extraction from propolis

An ultrasound assisted method was investigated to extract bioactive compounds from propolis. This method was based on a simple ultrasound treatment using ethanol as an extraction medium to facilitate the disruption of the propolis cells. Four different variables were chosen for determining the influence on the extraction efficiency: ultrasonic amplitude, ethanol concentration, temperature and time; the variables were selected by Box-Behnken design experiments. These parameters were optimised in order to obtain the highest yield, and the results exhibited the optimum conditions for achieving the goal as 100% amplitude of ultrasonic treatment, 70% solvent concentration, 58 °C and 30 min. The extraction yield under modified optimum extraction conditions was, as follows: 459.92 mg GAE/g of TPC, 220.62 mg QE/g of TFC and 1.95% of balsam content. The results showed that the ultrasound assisted extraction was suitable for bioactive compounds extraction from propolis. The most abundant phenolic compound was kaempferol (228.8 mg/g propolis) followed by myricetin (115.5 mg/g propolis), luteolin (27.2 mg/g propolis) and quercetin (25.2 mg/g propolis).     

Ultrasound-assisted extraction of phenolic acids,flavonols, and flavan-3-ols from muscadine grape skins and seeds using natural deep eutectic solvents and predictive modelling by artificial neural networking

The objective of this study was to investigate the extraction efficiency of 9 natural deep eutectic solvents (NDES) with the assistance of ultrasound for phenolic acids, flavonols, and flavan-3-ols in muscadine grape (Carlos) skins and seeds in comparison to 75% ethanol. Artificial neural networking (ANN) was applied to optimize NDES water content, ultrasonication time, solid-to-solvent ratio, and extraction temperature to achieve the highest extraction yields for ellagic acid, catechin and epicatechin. A newly formulated NDES (#1) consists of choline chloride: levulinic acid: ethylene glycol 1:1:2 and 20% water extracted the highest amount of ellagic acid in the skin at 22.1 mg/g. This yield was 1.73-fold of that by 75% ethanol. A modified NDES (#3) consisting of choline chloride: proline: malic acid 1:1:1 and 30% water extracted the highest amount of catechin (0.61 mg/g) and epicatechin (0.89 mg/g) in the skin, and 2.77 mg/g and 0.37 mg/g in the seed, respectively. The optimal yield of ellagic acid in the skin using NDES #1 was 25.3 mg/g (observed) and 25.3 mg/g (predicted). The optimal yield of (catechin + epicatechin) in seed using NDES #3 was 9.8 mg/g (observed) and 9.6 mg/g (predicted). This study showed the high extraction efficiency of selected NDES for polyphenols under optimized conditions.     

Aqueous ionic liquid based ultrasonic assisted extraction of eight ginsenosides from ginseng root

We developed an aqueous ionic liquid based ultrasonic assisted extraction (ILUAE) method for the extraction of the eight ginsenosides (ginsenoside-Rg1, -Re, -Rf, -Rb1, -Rc, -Rb2, -Rb3 and -Rd) from ginseng root. A series of l-alkyl-3-methylimidazolium ionic liquids differing in composition of anions and cations were evaluated for extraction efficiency. The results indicated that the ILUAE method has a remarkable ability to improve the extraction efficiency of ginsenosides. In addition, the ILUAE procedure was also optimized on some ultrasonic parameters, such as the IL concentration, solvent to solid ratio and extraction time. Under these optimal conditions (e.g., with 0.3 M [C₃MIM]Br, solvent to solid ratio of 10:1 and extraction time of 20 min), this approach gained the highest extraction yields of total ginsenosides 17.81 ± 0.47 mg/g. Compared with the regular UAE, the proposed approach exhibited 3.16 times higher efficiency and 33% shorter extraction time, which indicated that ILUAE has a broad prospect for sample preparation of medicinal plants.     

Comparison of ultrasound and microwave assisted extraction of diosgenin from Trigonella foenum graceum seed

From the recent market trend, there is a huge demand for the bioactive compounds from various food matrices that could be capable enough to combat the emerging health effects in day-to-day life. Fenugreek is a well-known spice from ancient times for its medicinal and health benefits. In the present study, two methods of green extraction microwave (MAE) and ultrasound (UAE) assisted were studied in regard of extraction of fenugreek diosgenin. In this study, solvent type (acetone, ethanol, hexane and petroleum ether), solvent concentration (40, 60, 80 and 100%) and treatment time (1.5, 3.0, 4.5 and 6.0 min and 30, 40, 50 and 60 min for MAE and UAE method respectively) was varied to observe the effect of these parameters over extract yield and diosgenin content. The results of this study revealed that treatment time, type of solvent and its concentration and method adopted for extraction of diosgenin has significant effect. In relation with better yield extract and diosgenin content, the yield of fenugreek seed extract was 7.83% with MAE and 21.48% with UAE of fenugreek seed powder at 80% ethanol concentration at 6 and 60 min respectively. The content of diosgenin was observed in fenugreek seed powder extract was 35.50 mg/100 g in MAE and 40.37 mg/100 g in UAE with 80% ethanol concentration at 6 and 60 min respectively. The overall range of yield of fenugreek extract was varied from 1.04% to 32.48% and diosgenin content was 15.82 mg/100 g to 40.37 mg/100 g of fenugreek seed powder including both extraction methods. This study revealed that UAE would impose better ways for preparing fenugreek extract and observing diosgenin content from fenugreek seeds.     

Combination of liquid-phase pulsed discharge and ultrasonic for saponins extraction from lychee seeds

A skillfully combined method of liquid-phase pulsed discharge and ultrasonic (LPDU) had been developed for saponins extraction from lychee seeds. Single factor and response surface methods were used to optimize the system, respectively. The optimized conditions included 30% aqueous ethanol, 62.66 mL/g ratio of liquid to solid, 3 mm centre hole diameter of hollow electrode, 123 mL/min flow velocity, length of serpentine pipe of 15 cm, 276 W ultrasonic power, 47 °C ultrasonic temperature, and discharge voltage was fixed at 14 kV. Under these conditions, it obtained a maximum saponins yield of 51.30 ± 0.08 mg/g with 10 min, which was higher than those of LPD (42.33 ± 0.98 mg/g) with 24 min, ultrasonic assisted extraction (UAE) (41.80 ± 1.31 mg/g) with 30 min and maceration (38.72 ± 1.13 mg/g) with 180 min. Meanwhile, the energy consumption of LPDU was 7560 kJ/kg, which was notably lower than those of LPD (8820 kJ/kg), UAE (25875 kJ/kg) and maceration (10248 kJ/kg). We found that the saponin constituents of LPDU were similar to LPD, UAE, ME by HPLC content detection method, and found that LPDU had the highest degree of tissue damage after scanning electron microscope (SEM) comparison, which verified the reason for its high extraction efficiency. The results showed that LPDU was an effective technology for saponins extraction, which may be potentially applied in cosmetics, medicines and food chemistry.     

Recovery of β-carotene from pumpkin using switchable natural deep eutectic solvents

The aim of the present research was to develop green and sustainable extraction procedure for β-carotene recovery from pumpkin. A series of hydrophobic natural deep eutectic solvents (NADESs) based on fatty acids were prepared to establish high extraction efficiency of β-carotene and to increase stability of extracted carotenoids from the pumpkin. To intensify extraction process, NADES composed of C8 and C10 fatty acids (3:1) was selected and coupled with ultrasound assisted extraction. Response surface methodology and artificial neural network model (ANN) model was adopted to analyze significance of extraction parameters demonstrating high prediction levels of the β-carotene yield, experimentally confirming the maximum β-carotene content of 151.41 µg/mL at the optimal process condition. Extracted carotenoids in the optimal NADES extract have shown high stability during the storing period of 180 days. A switchable-hydrophilicity eutectic solvent system has been introduced as a successful way to recover extracted carotenoids from the NADES solvent. It was capable of precipitating 90% of carotenoids present in the extract. The proposed procedure is simple, easily scalable and has minimal impact on operators and the environment.     

Aqueous ionic liquid based ultrasonic assisted extraction of four acetophenones from the Chinese medicinal plant Cynanchum bungei Decne

In this study, an aqueous ionic liquid based ultrasonic assisted extraction (ILUAE) method for the extraction of the four acetophenones, namely 4-hydroxyacetophenone (1), 2,5-dihydroxyacetophenone (2), baishouwubenzophenone (3) and 2,4-dihydroxyacetophenone (4) from the Chinese medicinal plant Cynanchum bungei was developed. Three kinds of aqueous l-alkyl-3-methylimidazolium ionic liquids with different anion and alkyl chain were investigated. The results indicated that ionic liquids (ILs) showed remarkable effects on the extraction efficiency of acetophenones. In addition, the ILUAE, including several ultrasonic parameters, such as the ILs concentration, solvent to solid ratio, power, particle size, temperature, and extraction time have been optimized. Under these optimal conditions (e.g., with 0.6 M [C₄MIM]BF₄, solvent to solid ratio of 35:1, power of 175 W, particle size of 60–80 mesh, temperature of 25 °C and time of 50 min), this approach gained the highest extraction yields of four acetophenones 286.15, 21.65, 632.58 and 205.38 μg/g, respectively. The proposed approach has been evaluated by comparison with the conventional heat-reflux extraction (HRE) and regular UAE. The results indicated that ILUAE is an alternative method for extracting acetophenones from C. bungei.     

Physicochemical and antioxidative properties of ultrasound-assisted extraction of mahua (Madhuca longifolia) seed oil in comparison with conventional Soxhlet and mechanical extractions

Ultrasound-assisted solvent extraction (UAE) was applied to extract underutilized Madhuca longifolia seed oil. The effect of extraction time, temperature, solvent type, solvent/sample ratio, and amplitude on the oil yield and recovery were investigated. Approximately 56.97% of oil yield and 99.54% of oil recovery were attained using mild conditions of 35 min, 35 °C, 40% amplitude, isopropanol to acetone (1:1), and solvent to sample (20 mL/g). UAE oil yield and recovery were comparable with Soxhlet extraction (SXE) whilst mechanical pressing (ME) yielded < 50% of UAE recovery. UAE does not affect the fatty acids composition (46% C18:1; 22% C16:0; 21% C18:0, 10% C18:2), and triacylglycerol profile (23% POO, 17% POS, 16% SOO, and 14% POP). Interestingly, UAE extracted oil conferred remarkably (P < 0.05) higher antioxidant capacity (IC₅₀ of DPPH 106.60 mg/mL and ABTS 39.80 mg/mL) than SXE (IC₅₀ of DPPH 810.40 mg/mL and ABTS 757.43 mg/mL) or ME (IC₅₀ of DPPH 622.38 mg/mL and ABTS 392.87 mg/mL).     

Comparison of ultrasound-assisted extraction with conventional extraction methods of oil and polyphenols from grape (Vitis vinifera L.) seeds

Ultrasound-assisted extraction (US) carried out at 20 KHz, 150 W for 30 min gave grape seed oil yield (14% w/w) similar to Soxhlet extraction (S) for 6 h. No significant differences for the major fatty acids was observed in oils extracted by S and US at 150 W. Instead, K₂₃₂ and K₂₆₈ of US- oils resulted lower than S-oil. From grape seeds differently defatted (S and US), polyphenols and their fractions were extracted by maceration for 12 h and by ultrasound-assisted extraction for 15 min. Sonication time was optimized after kinetics study on polyphenols extraction. Grape seed extracts obtained from seeds defatted by ultrasound (US) and then extracted by maceration resulted the highest in polyphenol concentration (105.20 mg GAE/g flour) and antioxidant activity (109 Eq αToc/g flour).     

Comparison of different ultrasound assisted extraction techniques for pectin from tomato processing waste

Concept of waste to wealth is a hot topic with research ongoing globally to reduce carbon footprint. In an effort to follow up this cause present study focused on tomato industry waste specifically the peel of tomatoes for extraction of pectin. Pectin extraction was performed using five different extraction techniques (Ultrasound assisted extraction (UAE); microwave assisted extraction (MAE); ohmic heating assisted extraction (O_HAE); ultrasound assisted microwave extraction (UAME) and ultrasound assisted ohmic heating extraction (UAO_HE) at different power levels to study its extraction and degradation kinetics and in turn to optimize the extraction process. The extracted pectin yield ranged from 9.30% for O_HAE to 25.42% for MAE. Also, there was very less difference in the yield of MAE and UAME extracted pectin, but at the cost of major difference in degree of esterification 59.76 ± 0.70 and 73.33 ± 1.76%, respectively. In addition, all the pectin extracted under optimized conditions was having acceptable purity, [Galacturonic acid (GalA) content ranged from 675.8 ± 11.31 to 913.3 ± 20.50 g/kg of pectin]. FTIR analysis confirmed the presence of functional groups in the finger print region of identification for polysaccharide in all the extracted pectin. According to obtained results, UAME can be considered as better green extraction technology in terms of extraction yield as well as in quality of pectin compared to the other treatments used. Therefore, results suggest that UAME can be used as an efficient pectin extraction method from tomato processing waste.     

Green ultrasound-assisted extraction of carotenoids based on the bio-refinery concept using sunflower oil as an alternative solvent

A green, inexpensive and easy-to-use method for carotenoids extraction from fresh carrots assisted by ultrasound was designed in this work. Sunflower oil was applied as a substitute to organic solvents in this green ultrasound-assisted extraction (UAE): a process which is in line with green extraction and bio-refinery concepts. The processing procedure of this original UAE was first compared with conventional solvent extraction (CSE) using hexane as solvent. Moreover, the UAE optimal conditions for the subsequent comparison were optimized using response surface methodology (RSM) and ultra performance liquid chromatography – diode array detector – mass spectroscopy (UPLC–DAD–MS). The results showed that the UAE using sunflower as solvent has obtained its highest β-carotene yield (334.75 mg/l) in 20 min only, while CSE using hexane as solvent obtained a similar yield (321.35 mg/l) in 60 min. The green UAE performed under optimal extraction conditions (carrot to oil ratio of 2:10, ultrasonic intensity of 22.5 W cm^?2, temperature of 40 °C and sonication time of 20 min) gave the best yield of β-carotene.     

Ultrasound-assisted polysaccharide extraction from Cercis chinensis and properites,antioxidant activity of polysaccharide

The purpose of the study was to improve the extraction of polysaccharide from the leaves of Cercis chinensis Bunge using ultrasound, and compare the difference between boiling and ultrasound extraction in terms of polysaccharide content, monosaccharide compounds, and evaluate how the factors affected the bioactivity. The best conditions, according to the single factor experiments and the Box-Bohnken design (BBD), were an intensity of ultrasound of 180 W, duration of extraction of 40 min, proportion of water to material of 15:1 (g/g), and a higher polysaccharide yield of 20.02 ± 0.55 (mg/g) than in boiling extraction (16.09 ± 0.82 mg/g). The antioxidative experiment suggested the polysaccharide by ultrasound exhibited higher DPPH, hydroxyl radical scavenging capacities, and reducing power at 1.2–1.4 mg/mL, which was superior to the boiling polysaccharide. Further analysis showed that the ultrasonic purified polysaccharides like Gla, N-Glu, and GluA contained more total sugar and uronic acids than the boiling method did. This may indicate that the ultrasonic isolation of the polysaccharides increase the antioxidant activity of the polysaccharides.     

Extracting myricetin and dihydromyricetin simultaneously from Hovenia acerba seed by Ultrasound-Assisted extraction on a lab and small Pilot-Scale

The flavonoids myricetin and dihydromyricetin are significant components of Hovenia acerba seed. In this work, myricetin and dihydromyricetin were extracted from Hovenia acerba seed using an ultrasound-assisted technique, and the extraction parameters were adjusted using the response surface design approach. HPLC was used to assess the yield of myricetin and dihydromyricetin. According to the data, myricetin and dihydromyricetin yields were 0.53 mg/g and 4.06 mg/g at a 60 % ethanol solution concentration, 180 W of ultrasonic irradiation power, a 20 mL/g ratio of liquid to solid, and a 40 °C optimal extraction temperature. The aforementioned findings are virtually in agreement with the experimental findings suggested by the model. The study mentioned above thus offers a means of separating and developing useful components of natural goods.     

Effects of various factors of ultrasonic treatment on the extraction recovery of drugs from fish tissues

In the present research, a combined extraction method of ultrasound-assisted extraction (UAE) in conjunction with solid phase extraction (SPE) was applied to isolation and enrichment of selected drugs (metoprolol, ticlopidine, propranolol, carbamazepine, naproxen, acenocumarol, diclofenac, ibuprofen) from fish tissues. The extracted analytes were separated and determined by ultra-high performance liquid chromatography with UV detection (UHPLC–UV) technique. The selectivity of the developed UHPLC–UV method was confirmed by comparison with ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) analysis.The important parameters, such as composition of type and pH of extraction solvent, solid/liquid rate volume of extraction solvent and number of extraction cycles were studied. The ultrasonic parameters, such as time, power and temperature of the process were optimized by using a half-fraction factorial central composite design (CCD). The mixture of 10 mL of methanol and 7 mL of water (pH 2.2) (three times) was chosen for the extraction of selected drug from fish tissues. The results showed that the highest recoveries of analytes were obtained with an extraction temperature of 40 °C, ultrasonic power of 300 W, extraction time of 30 min.Under the optimal conditions, the linearity of method was 0.12–5.00 μg/g. The determination coefficients (R²) were from 0.979 to 0.998. The limits of detection (LODs) and limits of quantification (LOQs) for the extracted compounds were 0.04–0.17 μg/g and 0.12–0.50 μg/g, respectively. The recoveries were between 85.5% and 115.8%.     

Ultrasonic-enhanced surface-active ionic liquid-based extraction and defoaming for the extraction of psoralen and isopsoralen from Psoralea corylifolia seeds

Recently, integrated and sustainable methods for extracting active substances from plant materials using green solvents, i.e., ionic liquids, have gained increasing attention. Ionic liquids show superiority over conventional organic solvents; however, they also exhibit negative factors and problems, such as high viscosity, poor water intermiscibility, intensive foaming and poor affinity for fat-soluble substances. The proposed method utilizes ultrasonic-enhanced surface-active ionic liquid-based extraction and defoaming (UESILED) to improve the extraction efficiency of ionic liquids. Single-factor experiments and a Box-Behnken design (BBD) were utilized to optimize the extraction procedure. The optimal conditions were as follows: extraction solvent, [C₁₀MIM]Br; ultrasonic treatment time, 28 min; ultrasonic irradiation power, 437 W; liquid–solid ratio, 10 mL/g; particle size, 60 ~ 80 mesh; ultrasonication temperature, 313 K; and [C₁₀MIM]Br solution concentration, 0.5 mol/L. In comparison with those of other reference extraction methods, the proposed method exhibited higher yields of two furocoumarins and operational feasibility. Moreover, the mechanism of UESILED was elaborated in terms of accelerating infiltration, dissolution and defoaming. The feasible and efficient ultrasonic-enhanced ionic liquid-based extraction established in this study strongly contributes to overcoming the limitations of ionic liquid solvents. The present research indicates that this improved process will be beneficial for the extraction of other fat-soluble substances and provides promising concepts and experimental data.     

Optimization of ultrasound-assisted extraction of bioactive compounds from coffee pulp using propylene glycol as a solvent and their antioxidant activities

In the cosmetic and pharmaceutical industries, it has been increasingly popular to use alternative solvents in the extraction of bioactive compounds from plants. Coffee pulp, a by-product of coffee production, contains different phenolic compounds with antioxidant properties. The effects of polyols, amplitude, extraction time, solvent concentration, and liquid–solid ratio on total phenolic content (TPC) using ultrasound-assisted extraction (UAE) were examined by single-factor studies. Three main factors that impact TPC were selected to optimize the extraction conditions for total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), and their antioxidant activities using the Box-Behnken design. Different extraction methods were compared, the bioactive compounds were identified and quantified by liquid chromatography triple quadrupole mass spectrometer (LC-QQQ), and the cytotoxicity and cellular antioxidant activities of the extract were studied. According to the response model, the optimal conditions for the extraction of antioxidants from coffee pulp were as follows: extraction time of 7.65 min, liquid–solid ratio of 22.22 mL/g, and solvent concentration of 46.71 %. Under optimized conditions, the values of TPC, TFC, TTC, 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging assay, and Ferric reducing antioxidant power assay (FRAP) were 9.29 ± 0.02 mg GAE/g sample, 58.82 ± 1.38 mg QE/g sample, 8.69 ± 0.25 mg TAE/g sample, 7.56 ± 0.27 mg TEAC/g sample, 13.59 ± 0.25 mg TEAC/g sample, and 10.90 ± 0.24 mg FeSO₄/g sample, respectively. Compared with other extraction conditions, UAE with propylene glycol extract (PG-UAE) was significantly higher in TPC, TFC, TTC, DPPH, ABTS, and FRAP response values than UAE with ethanol (EtOH-UAE), maceration with propylene glycol (PG-maceration), and maceration with ethanol (EtOH -maceration) (p < 0.05). Major bioactive compounds detected by LC-QQQ included chlorogenic acid, caffeine, and trigonelline. At higher concentrations starting from 5 mg/ml, PG-UAE extract showed higher cell viability than EtOH-UAE in both cytotoxicity and cellular antioxidant assays. The researcher expects that this new extraction technique developed in this work could produce a higher yield of bioactive compounds with higher biological activity. Therefore, they can be used as active ingredients in cosmetics (anti-aging products) and pharmaceutical applications (food supplements, treatment for oxidative stress-related diseases) with minimal use of chemicals and energy.     

Ultrasound-assisted extraction and purification of schisandrin B from Schisandra chinensis (Turcz.) Baill seeds: Optimization by response surface methodology

The objective of this study is to develop a process consisting of ultrasonic-assisted extraction, silica-gel column chromatography and crystallization to optimize pilot scale recovery of schisandrin B (SAB) from Schisandra chinensis seeds. The effects of five independent variables including liquid–solid ratio, ethanol concentration, ultrasonic power, extraction time, and temperature on the SAB yield were evaluated with fractional factorial design (FFD). The FFD results showed that the ethanol concentration was the only significant factor for the yield of SAB. Then, with the liquid–solid ratio 5 (mL/g) and ultrasonic power 600 W, the other three parameters were further optimized by means of response surface methodology (RSM). The RSM results revealed that the optimal conditions consisted of 95% ethanol, 60 °C and 70 min. The average experimental SAB yield under the optimum conditions was found to be 5.80 mg/g, which was consistent with the predicted value of 5.83 mg/g. Subsequently, a silica gel chromatographic process was used to prepare the SAB-enriched extract with petroleum ether/acetone (95:5, v/v) as eluents. After final crystallization, 1.46 g of SAB with the purity of 99.4% and the overall recovery of 57.1% was obtained from 400 g seeds powder. This method provides an efficient and low-cost way for SAB purification for pharmaceutical industrial applications.     

An effective method for extracting anthocyanins from blueberry based on freeze-ultrasonic thawing technology

The aim of this study was to develop an effective method for extracting anthocyanins from blueberry Vaccinium spp. (ABVS) using freeze-ultrasonic thawing technology (FUTE). Various parameters including freezing time, ultrasonic time, ultrasonic temperature and liquid–solid ratio were optimized by a single-factor design and multiple response surface methodology. The amounts of extracted anthocyanin and cyanidin-3-O-glucoside were measured by UV and HPLC respectively. The maximum yield of anthocyanins was achieved by freezing the samples for 5.43 min in liquid nitrogen at the liquid–solid ratio of 24.07:1 mL/g, followed by ultrasonic thawing at 41.64 °C for 23.56 min. The yield and antioxidant effects of ABVS extracted using FUTE, ultrasound-assisted extraction (UAE) and freeze-thawing extraction (FTE) were compared in order to determine the overall efficacy of FUTE. In addition to the higher content, FUTE extracted ABVS showed greater ability to scavenge DPPH·, ABTS⁺ and superoxide anions, and inhibit lipid peroxidation compared to the ABVS extracted by UAE or FTE. The reducing power of the FUTE-derived ABVS was intermediate between that of the UAE and FTE samples. Taken together, FUTE can rapidly and effectively extract ABVS and retain its antioxidant capacity.     

Investigation on ultrasound-assisted extraction of salvianolic acid B from Salvia miltiorrhiza root

It is reported that salvianolic acid B, a bioactive phenolic compound contained in the root of Salvia miltiorrhiza, exhibits a much stronger activity in free radical scavenging and antioxidance than those of vitamin E. When a conventional refluxing method is adopted to extract salvianolic acid B from the root, in which the materials are subjected to higher temperature and longer time, the yield of this phenolic compound is lower due to the possibility of its hydrolysis to tanshinol. However, a higher extraction yield can be achieved over a shorter time period and lower temperature when an ultrasound-assisted extraction method is used. This paper investigated the parameters influencing the extraction of salvianolic acid B. Factors such as extraction time, frequency of the ultrasound, the ratio of solvent to material, and types of extraction solvent were examined. A comparison was also conducted between conventional refluxing and ultrasound-assisted extraction. Results showed that the optimal parameters to extract salvianolic acid B from the root of S. miltiorrhiza were as follows: ultrasonic frequency: 45 Hz; solvent: 60% aqueous ethanol; extraction temperature: 30 °C; extraction time duration: 25 min.; ratio of solvent to material: 20:1 (v/w, ml/g). Under these conditions, the yield of salvianolic acid B was 5.17 mg/g (33.93 mg/g) higher than those with conventional refluxing method (28.76 mg/g), indicating that the efficiency and the yield of ultrasound-assisted extraction method are higher than reflux method, and the hydrolysis of salvianolic acid B to tanshinol is effectively avoided.     

Optimizing the antioxidant biocompound recovery from peach waste extraction assisted by ultrasounds or microwaves

The possibility to valorize peach juice waste, either frozen or air-dried, through microwave (MAE) and ultrasound assisted extraction (UAE) was evaluated. MAE power, UAE amplitude and time were optimized using a 2²-factorial design. For frozen waste, optimal MAE (540 W, 50 s) and UAE (23%, 120 s) processes gave extracts presenting analogous content (on 100 g dry matter) of polyphenols (309–317 mg GAE), flavonoids (94–120 mg QE), anthocyanins (8–9 mg CGE), and similar antioxidant activity (2.1–2.2 mg TE). Extracts from dried waste resulted higher in polyphenols (630–670 mg GAE) but lower in flavonoids (75–90 mg QE), anthocyanins and vitamin C (not detectable). Although developing an energy density 2-fold higher than that of UAE, MAE more efficaciously extracted vitamin C (108 mg/100 g dm) and required half extraction time (50 s). MAE would also be less impactful than UAE in terms of greenhouse gas emission and energy requirements on industrial scale. The industrial valorization of peach waste through the application of microwave or ultrasound assisted extraction requires quantitative data, able to encourage company interest and investment. This study not only identifies optimal MAE and UAE parameters to assist the extraction of peach waste bioactive compounds but also provides a preliminary estimation of the potential economic and environmental impact on an industrial scale of these technologies.