Comparative evaluation of atmospheric and vacuum microwave‐assisted extraction of bioactive compounds from fresh and dried Centella asiatica L. leaves

Microwave‐assisted extraction (MAE) involves extraction under higher‐temperature and oxygen‐rich environment, which may cause degradation of bioactive compounds being extracted. Reducing the extraction temperature by reducing the system pressure is thus of interest. Nevertheless, information is lacking on the kinetics of vacuum microwave‐assisted extraction (VMAE) at various pressures. Detailed temperature evolution of a material–solvent mixture during VMAE is also not available. This study investigated the extraction kinetics of triterpene saponins and phenolics from both fresh and dried Centella leaves during MAE and VMAE at various pressures. In the case of fresh leaves, the maximum contents of triterpene saponins were reached when VMAE was performed at 60 kPa, whereas the maximum total phenolics content (TPC) was achieved when the extraction was performed at atmospheric condition. In the case of dried leaves, the maximum triterpene saponins contents as well as TPC were achieved when extraction was performed at atmospheric condition.     

Effect of solvents on polyphenol recovery and antioxidant activity of isolates of Asparagus Officinalis roots from Chinese and New Zealand cultivars

Nine solvents of varying polarity (water, methanol, ethanol, isopropyl alcohol, acetone, n‐butyl alcohol, ethyl acetate, chloroform and petroleum ether) were used to determine the optimal extraction solvent that gives the highest yield of bioactive compounds from six Asparagus Officinalis L root (AR) cultivars from China and New Zealand. The contents of total phenolics (TPC), total flavonoids (TFC), total saponins (TSC) and caffeic acid (CA) were determined. Antioxidant assessments included ferric reducing/antioxidant power (FRAP), 2, 2′‐azinobis‐(3‐ diphenyl‐ethylbenzothiazoline‐6‐sulphonic acid) radical cation (ABTS) and β‐carotene bleaching activity assays. The results indicated that yellow AR from China had the highest content of TPC, TFC, TSC and CA compared to other AR cultivars. The most effective solvents for bioactive compound recoveries and antioxidant activities from A. officinalis L root extraction were ethanol and methanol. The content of CA in ethanol extracts of yellow AR achieved 92.0 mg g^?1 DE.     

Optimisation of the microwave-assisted extraction process for four main astragalosides in Radix Astragali

An efficient microwave-assisted extraction (MAE) technique was employed in extracting astragalosides I–IV from Radix Astragali. Astragalosides were quantified by liquid chromatography-electrospray ionisation mass spectrometry (LC-ESI/MS). The MAE procedure was optimised, validated and compared with other conventional extraction techniques. MAE gave the best result due to the highest extraction efficiency within the shortest extraction time. The optimal conditions of MAE were: employing 80% ethanol as solvent, ratio of solid/liquid 1:25 (g/ml), temperature 70 °C, irradiation power 700 W and three extraction cycles, each 5 min. Scanning electron microscopy (SEM) images of Radix Astragali materials after different extractions were obtained to provide visual evidence of the disruption effect. This is the first report on combining MAE with LC-ESI/MS for the extraction and quantification of astragalosides I–IV in Radix Astragali. The developed MAE method provided a good alternative for the extraction of triterpenoid saponins in Radix Astragali as well as other herbs.     

Comparative evaluation of microwave‐assisted extraction and preheated solvent extraction of bioactive compounds from a plant material: a case study with cabbages

Preheated solvent extraction (PSE) was evaluated via the analysis of the extraction kinetics, microstructure of extracted samples and energy consumption as alternative to microwave‐assisted extraction (MAE). Cabbage outer leaves and ethanol were used as test material and extraction solvent, respectively. MAE was first optimised in terms of glucosinolates and phenolics yields; total antioxidant activity of the extracts was also assessed. MAE at a specific absorbed power of 0.37 W g^?1 for 9 min was selected as optimum condition to extract glucosinolates and phenolics, while PSE was optimised at 6 min of the extraction. The highest normalised total glucosinolates and phenolic contents as well as antioxidant activities of the extracts obtained via MAE were not significantly different from those obtained via PSE. Confocal laser scanning microscopy revealed no significant differences in cabbage cell damages rendered by MAE and PSE. PSE nevertheless exhibited slightly higher specific energy consumption than MAE.     

Optimization of extraction conditions for improving solubility of peanut protein concentrates by response surface methodology

By ethanol precipitation and physical separation procedures, the peanut protein concentrate (PPC) was isolated from defatted peanut flour (DPF) and the extraction times were determined as twice. The effects of liquid-to-solid ratio, ethanol concentration and reaction temperature on the solubility of PPC were studied for the primary extraction and the later two factors were studied for the second extraction by response surface methodology (RSM). The results showed that for both of the second-order models, the coefficient determination (R²) was good and a liquid-to-solid ratio of 11.79: 1 (v/w), an ethanol concentration of 85 mL/100 mL, an extract temperature of 36.35 °C for the primary extraction and a corresponding list of variables of 8:1 (v/w), 97.50 mL/100 mL and 38.40 °C for the secondary extraction were found to be optimal for the protein extraction from defatted peanut flour. By means of additional experiments, the adequacy of the model was confirmed.     

Optimisation of the microwave‐assisted extraction process for six phenolic compounds in Agaricus blazei murrill

An efficient microwave‐assisted extraction (MAE) technique was employed in the extraction of phenolic compounds from Agaricus blazei murrill, and phenolic compounds were quantified by High‐performance liquid chromatography (HPLC). The MAE procedure was optimised, validated and compared with other conventional extraction techniques. MAE gave the best result because of the highest extraction efficiency within the shortest extraction time. The optimal conditions of MAE were 60% ethanol, ratio of solid/liquid 1:30, temperature 110 °C, irradiation power 500 W and three extraction cycles, each 5 min. This is the first report on combining MAE with HPLC for the extraction and quantification of phenolic compounds in A. blazei murrill. The developed MAE method provided a good alternative for the extraction of phenolic compounds in A. blazei murrill as well as other materials.     

枇杷花叶主要功能成分分步提取及其压片糖果工艺配方优化研究

目的:寻求合适工艺提取枇杷花叶中的总三萜酸、总黄酮、多糖,并研发枇杷花叶提取物压片糖果制备的最优配方工艺。方法:枇杷花、叶洗净烘干,用搅拌机粉碎、过筛,采用分步法提取花叶(1:1,g/g)中总三萜酸、总黄酮和多糖,以单因素实验法确定其合适的提取工艺参数;在单因素实验基础上,采用正交实验(L₉(3³))优化枇杷花叶提取物压片糖果的工艺配方。结果:总三萜酸提取的合适工艺为100%乙醇、料液比1:40(g/mL)、提取温度50 ℃、提取时间2 h,粗提物得率为1.6%;总黄酮提取的合适工艺为60%乙醇、料液比1:20(g/mL)、提取温度50 ℃、提取时间2 h,粗提物得率为17.9%;多糖水提的合适工艺为料液比1:15(g/mL)、提取温度80 ℃、提取时间2 h,粗提物得率为1.0%。枇杷花叶提取物压片糖果的最优配方为:枇杷花叶提取物(总三萜酸:总黄酮:多糖=2:18:1,g/g/g)0.2 g、填充剂(微晶纤维素:预胶化淀粉=1:1,g/g)7.5 g、调味剂(木糖醇:柠檬酸=50:1,g/g)5.0 g、硬脂酸镁1%。结论:文章所涉及的提取...     

Green ultra-high pressure extraction of bioactive compounds from Haematococcus pluvialis and Porphyridium cruentum microalgae

Microalgae are considered prolific sources of bioactive compounds that can be useful for nutraceuticals. In this study, the potential of ultra-high pressure extraction (UHPE) for the simultaneous cell disruption and extraction of bioactives from two microalgae species, Haematococcus pluvialis and Porphyridium cruentum, was evaluated. The variables studied to extract carotenoids for H. pluvialis were pressure (100–600 MPa) and number of cycles (1 and 3 cycles) whereas the variables studied to obtain bioactives such as B-phycoerythrin, carotenoids, and PUFAs for P. cruentum were pressure (100–600 MPa) and different extraction solvents (water, ethanol, ethyl acetate or ethanol/d-limonene), generally recognized as safe (GRAS). The UHPE results showed significant increase on the extraction of carotenoids (109.74–119.34 mg per g extract) from H. pluvialis using 1 cycle of 20 min regardless of the pressure used. For P. cruentum, an UHPE with water provided extracts enriched in B-phycoerythrin (up to 144.43 mg per g extract), while subsequent UHPE using ethanol, ethyl acetate or ethanol/d-limonene 1:1 (v/v) provided extracts enriched in carotenoids (up to 65.05 mg per g extract) and polyunsaturated fatty acids (mainly eicosapentanoic acid and linoleic acid). Therefore, UHPE proved to be a viable green alternative for the recovery of bioactives from microalgae biomass.Industrial relevance: Microalgae are promising sources of bioactives such as B-phycoerythrin, carotenoids and polyunsaturated fatty acids. The potential of ultra-high-pressure extraction (UHPE) has been demonstrated as a fast and viable eco-friendly alternative using GRAS solvents (water, ethanol, ethyl acetate or ethanol/d-limonene) for the simultaneous cell disruption and extraction of these bioactives from Haematococcus pluvialis and Porphyridium cruentum. The bioactives obtained with one step or two step-UHPE process can be used in an array of food, cosmetic and pharmaceutical applications.     

Process optimisation of microwave‐assisted extraction of peony (Paeonia suffruticosa Andr.) seed oil using hexane–ethanol mixture and its characterisation

Ethanol and hexane mixture agent microwave‐assisted extraction (MAE) method was conducted to extract peony (Paeonia suffruticosa Andr.) seed oil (PSO). The aim of the study was to optimise the extraction for both yield and energy consumption in mixture agent MAE. The highest oil yield (34.49%) and lowest unit energy consumption (14 125.4 J g^?1) were obtained under optimum extraction condition: solid‐liquid ratio 0.37 g mL^?1, extraction time 3.72 min, extraction temperature 80.92 °C, ethanol ratio 20.00%. GC–MS results showed that unsaturated fatty acids (UFAs) accounted for 88.60% of total fatty acids in PSO. Moreover, linolenic acid content of 37.35% was the highest UFA and caused PSO to possess good nutrition. PSO in DPPH radical scavenging experiment showed that IC₅₀ value of 28.80 ± 2.13 mg mL^?1 exhibited strong antioxidant property. All experiments proved that mixed solvent MAE is an efficient and promising method to extract PSO. This method can effectively reduce the energy consumption and extraction time.     

Recovery of bioactive compounds from walnut (Juglans regia L.) green husk by supercritical carbon dioxide extraction

In this work, the use of supercritical carbon dioxide, a nontoxic solvent, was proposed to extract bioactive compounds from Juglans regia L. green husk and was compared to other traditional techniques based on solvents such as ethanol, methanol and water. Supercritical CO₂ was combined with ethanol as an organic modifier at a rate of 20% of the total flow to achieve greater extraction of polar compounds. The extracts were characterised in terms of extraction yields, antioxidant activity, total polyphenol content, phenolic acids, juglone, volatile organic compounds and antifungal activity. The results showed that the extracts obtained with supercritical CO₂ were rich in polyphenols (10750 mg GAE/100 g) and juglone (1192 mg/100 g) and exerted high antioxidant activity and antifungal activity compared with the tested fungi. Walnut green husk is not just a food industry waste but also an important economic source of bioactive compounds that could be used for food active packaging.     

罗汉果皂苷的微波提取(英文)

中药罗汉果是广西特产,本文采用微波辅助提取技术,从罗汉果中提取罗汉果皂苷,并优化出最佳的微波提取功率、微波辐射时间、固液比及原料的粉碎度。结果表明,最佳的微波辐射时间是5min、微波功率是495W、原料的粉碎度为不小于0.15mm及固液比为1:30,和传统的加热提取相比较,微波辅助提取的提取时间短,但具有较高的提取率。微波辅助提取的提取时间为5min时,提取率达76.56%,而传统的加热提取时间为2h时,提取率为68.46%。     

High-power ultrasonication-assisted extraction of soybean isoflavones and effect of toasting

The effect of high-power ultrasonication (HPU) on extraction of soybean isoflavones and components, including total phenolic and DPPH radical scavenging activities (RSA) were evaluated. Isoflavones from defatted soybean flakes were extracted using a bench scale HPU system at 20 kHz and varying amplitudes (18–54 μm) for 1 and 3 min. Aqueous acetonitrile, and aqueous ethanol based solvents were evaluated for extraction at samples-to-solvent ratios of 0.1:1 and 0.2:1. The non-sonication control extraction was with mixing with magnetic stirrer for 2 h. Preliminary data indicated 1.2–1.5 times more genistein recovery at 1, and 3 min sonication compared to control, however, total phenolic decreased. The genistein recovery was lower at higher sonication levels. RSA also decreased to 40% for HPU-assisted extractions. Total isoflavones recovery in HPU-assisted extractions increased from 600 to 5813 μg/g. The concentration of major isoflavone components, genistein, daidzein, and glycitein also increased by 10-fold. HPU for 3 min reduced the average particle size of treated soy flakes from 530 μm to 60 μm. Toasting at 150 °C of defatted soy flake for longer period of time led to higher aglycone concentration in extract; however, 2 h toasting was sufficient prior to HPU-assisted extraction.     

Effect of microwave‐assisted extraction on the release of polyphenols from ginger (Zingiber officinale)

The significance of different variables viz. temperature, time and solvent at constant power in microwave‐assisted extraction (MAE) process of ginger was studied and compared with conventional method. Aqueous ethanol (50%) provided higher yields of extract as well as the highest release of total polyphenols (TPP) than alcoholic solvents. The reason could be the high dielectric constant of aqueous ethanol as compared to alcohols. Microwave heating being a volumetric process, an exposure time of 1 min was found to be sufficient. The better penetration of microwaves and greater solubility at higher temperature resulted in higher yield of TPP and [6]‐gingerol. The resultant extract showed higher radical scavenging activity (RSA) values. Thus, MAE allowed higher recoveries compared to conventional extraction process, with improvement in the quantity and quality of extract in very short period of time.     

Comparative evaluation of physicochemical properties of Lingzhi (Ganoderma lucidum) as affected by drying conditions and extraction methods

Lingzhi (Ganoderma lucidum) is a high-potential mushroom which is used as a dietary supplement or a source of nutrients and antioxidant agents. The aims were to investigate the effect of drying conditions (hot air and vacuum dry) and to compare the extraction methods of microwave-assisted extraction (MAE) and pulsed electric field extraction (PEF) for obtaining triterpenes, flavonoid and polysaccharides. The favourable drying condition was 80 °C for 1 h and 37 min, which achieved 1.17 ± 0.05 mg quercetin/g of flavonoids and 11.49 ± 0.87 mg ursolic acid/g of triterpenes. The MAE condition was 800 W, 1 min 30 s extraction time and 65.35% ethanol, achieving polysaccharides of 13.08 mg glucose/g and triterpenes of 9.15 mg ursolic acid/g. Additionally, MAE was significantly more efficient than reflux and PEF methods. The application of microwave radiation is beneficial in saving time and solvent and also provides high extraction efficiency for dried Lingzhi.     

The optimization of microwave-assisted extraction of decursin from Angelica gigas Nakai root

Response surface methodology was used to display the characteristics of microwave‐assisted extraction (MAE) of soluble solids and decursin from Angelica gigas Nakai root, thereby allowing MAE conditions to be optimized. These included ethanol concentration, microwave power and extraction time. The maximal solid yield was predicted to be 44.2% under conditions of 44.9% ethanol concentration, 115.6 W microwave power and 5.8 min extraction time. Decursin content of the extract was estimated to be maximal at 2.52% using 97.7% ethanol, 90.2 W microwave power, and 6.1 min extraction time. The estimated optimal MAE conditions (67% ethanol, 100 W and 6 min) to maximize both components were verified by comparing estimated values with experimental values (42.2% soluble solids, 2.2% decursin), which were higher than those (35.8% solids, 2.0% decursin) obtained by conventional reflux extraction (60% ethanol, 95 °C and 6 h).     

超声辅助溶剂法提取白簕叶总皂苷的工艺研究

以白簕叶总皂苷提取率为评价指标,对超声波法提取分离白簕叶总皂苷进行了实验研究。考察了超声时间、超声功率、超声温度这三因素对总皂苷提取率的影响,并在单因素考察基础上,选用L9(34)正交表进行正交试验。结果表明 ：白簕叶总皂苷超声提取的最佳工艺条件为：超声时间35min,超声温度为60℃,超声功率80%,料液比为1:10,该条件下白簕叶总皂苷提取率为16.32%,高于索氏提取总皂苷提取率。     

Structural modification by different pretreatment methods to enhance microwave-assisted extraction of β-carotene from carrots

Since the structure of a material is a key factor influencing the extraction efficiency, any means to modify the structure to enhance extraction is attractive. As limited information is available on the effect of sample pretreatment prior to extraction on the extractability of a bioactive compound, the effects of selected pretreatment methods, i.e., soaking in citric acid, blanching in water as well as in citric acid, on the sample structure and subsequent microwave-assisted extraction (MAE) were investigated; carrots and β-carotene (as well as carotenoids) were selected as the test material and bioactive compound, respectively. A suitable condition to extract β-carotene in terms of the microwave power and extraction time was determined. Comparison between MAE and Soxhlet extraction was also made. At the optimized condition the contents of β-carotene and total carotenoids extractable from carrots blanched in water (29.74 and 58.04 mg/100 g dry basis) and in citric acid (32.08 and 61.62 mg/100 g dry basis) were significantly higher than those from the untreated carrots (23.26 and 51.79 mg/100 g dry basis). The antioxidant activities of the extracts obtained from carrots blanched in water and in citric acid were also higher than that from carrots with no pretreatment. Comparison between MAE and Soxhlet extraction revealed that the extract from MAE contained lower amounts of β-carotene and total carotenoids and exhibited lower antioxidant activity; the required MAE time was significantly shorter, however.     

Microwave-Assisted Extraction of Secoisolariciresinol Diglucoside��Method Development

An optimized microwave-assisted extraction (MAE) method was developed for extracting secoisolariciresinol diglucoside (SDG) from flaxseed. This paper presents the optimization of factors for maximizing the extraction yield of SDG. This work was conducted using the experimental domain identified in a previous study by means of screening designs, that is, samples of 1 g defatted flaxseed meal (DFM) were extracted with 50 ml NaOH of concentration of 0.5–1 M, at microwave power levels of 60–360 W, for 3–9 min, with the microwave power applied intermittently (power on 30 s/min) and continuously (power on 60 s/min). The MAE of SDG was maximized when 1 g DFM was extracted with 50 ml 0.5 M NaOH, at 135 W, for 3 min in intermittent power mode (power on 30 s/min). The optimized MAE achieved a 6% increase in the extraction yield (21.45 mg SDG per gram DFM) as opposed to a direct hydrolysis method (20.22 mg SDG per gram DFM). The MAE of SDG was governed by the microwave–NaOH interaction, which had a curvilinear dependence on the microwave power level, and linear dependence on the NaOH concentration. The microwave-induced effects accounted for a 10% increase in the SDG extraction yield (21.45 mg SDG per gram DFM) as opposed to a microwaveless control method (19.45 mg SDG per gram DFM). The optimized MAE method has good repeatability, a 97% recovery of the target compound; it is fast and efficient and can be used for precise quantification of SDG in flaxseed.     

Optimized microwave-assisted extraction of total phenolics (TP) from Ipomoea batatas leaves and its antioxidant activity

An efficient microwave-assisted extraction (MAE) technique was employed to extract total phenolics (TP) from sweetpotato [Ipomoea batatas (L.) Lam.] leaves (TPSL). The optimal conditions for microwave-assisted extraction of TPSL were determined by response surface methodology. A face-centered cubic design (FCD) was applied to evaluate the effects of three independent variables (microwave power, extraction time and ethanol proportion) on the recovery of TPSL. The correlation analysis of the mathematical-regression model indicated that quadratic polynomial model could be employed to optimize the microwave extraction of TPSL. From response surface plots, microwave power, extraction time and ethanol proportion exhibited independent and interactive effects on the extraction of TPSL. The optimal conditions to obtain the highest recovery of TPSL were as follows: microwave power, 302 W; extraction time, 123 s; ethanol proportion, 53% (v/v). Under these optimal conditions, the experimental values agreed with the predicted ones by analysis of variance. It indicated high fitness of the model used and the success of response surface methodology for optimizing TPSL extraction. After method development, the antioxidant activity of the MAE extract was preliminarily evaluated. MAE showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract with in shortest extraction time.Industrial Relevance: Sweet potato leaves have been neglected except for a partial use as livestock feed in China. This study describes the response surface optimization of microwave-assisted extraction (MAE) process for the enhanced recovery of total phenolics from sweetpotato leaves (TPSL). MAE showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. TPSL obtained using MAE showed potential for use in health-care food and pharmaceutical industry.     

玉米须总皂苷的微波辅助提取及抑菌活性研究

玉米须(Corn silk)是禾本科玉蜀属植物玉米的花柱和柱头,含有多糖类、黄酮类、皂苷类等多种活性成分。以玉米须为实验材料,总皂苷含量为考察指标,对玉米须总皂苷的微波辅助提取工艺进行了探讨,并对总皂苷提取物的抑菌活性进行了研究。在乙醇浓度、微波功率、微波时间、液料比等单因素试验的基础上,通过L9(34)正交试验,确定总皂苷微波辅助提取的最佳提取条件为:乙醇浓度70%、微波功率500W、微波时间60s、液料比40∶1。在上述条件下,总皂苷含量达2.905g/100g。微波辅助提取玉米须总皂苷的提取时间短,提取效率较高。玉米须总皂苷提取物对供试菌株均有不同程度抑制作用;其中,对沙门氏菌的抑制能力最强,其次为枯草杆菌、变形杆菌,对金黄色葡萄球菌的抑菌效果最差。