Optimisation of inulin extraction from globe artichoke (Cynara cardunculus L. subsp. scolymus (L.) Hegi.) by electromagnetic induction heating process

In this study, a D‐optimal design was used to optimise the extraction process conditions of inulin with a high degree of polymerisation from Globe artichoke heart (Cynara cardunculus L. subsp. scolymus (L.) Hegi.), using electromagnetic induction heating (EMIH) as a new extraction process. Four factors were simultaneously studied which were the extraction temperature (55–90 °C), the extraction time (30–120 min), the weight ratio (plant material dry weight/volume of distilled water: 5–10%) and the mode of heating (conventional or electromagnetic induction heating). It was found that the second‐order polynomial models developed by the response surface methodology (RSM) describe adequately the relationship between the factors and responses (extraction yield, viscosity and solubility of inulin). The optimum extraction conditions that led to a maximal extraction yield (45.98%) and an optimal viscosity (3.25 mL g^?1) of extracted inulin are temperature of 89.49 °C, extraction time of 120 min and a 5.01% of weight ratio using EIMH process. Fourier Transform InfraRed spectroscopy spectrum of the extracted inulin was identical to that of the native inulin. The analysis of the extract by thin‐layer chromatography confirms the absence of pectin in the final product, as well as the X‐ray diffraction analysis exhibits a semi‐crystalline structure of the biopolymer.     

Regulation of inducible nitric oxide synthase by arabinoxylans with molecular characterisation from wheat flour in cultured human monocytes

The immunomodulatory activity of the arabinoxylans (AXs) extracts from cereal sources has been reported to impart health benefits in terms of immune enhancement. This study investigated the effect of enzymatic extraction on extraction yield and structure of AXs from wheat flour pentosan fraction. Under the optimised conditions, the extraction yield of AXs reached up to 81.25%. Furthermore, the study determined whether water‐extracted AXs (WEAXs) and enzyme‐extracted AXs (E‐WEAXs) from wheat flour were able to differentially stimulate nitric oxide (NO) secretion through increased levels of inducible nitric oxide synthase (iNOS) in human U937 monocytes. The results indicated that AXs concomitantly induced (P < 0.05) both NO and iNOS productions in U937 monocytes compared to untreated cells. Compared with WEAXs, E‐WEAXs resulted in a higher proportion of low Mw (1–10 KDa) AXs (49.51% vs. 19.11% in WEAXs), a higher A/X ratio (0.83 vs. 0.48 in WEAXs) and a higher yield (12.83 ± 0.35% vs. 7.54 ± 0.47% in WEAXs). Moreover, E‐WEAXs induced significantly (P < 0.05) greater NO and iNOS production per million viable cells (61.8 ± 2.7 μm and 42.41 ± 3.83 ng respectively) than WEAXs (51.6 ± 2.6 μm and 33.46 ± 1.48 ng, respectively). The findings suggest AXs may heighten innate immune activity in the absence of infection or disease through an iNOS‐mediated stimulation of NO production. The immunomodulatory activity of the wheat‐derived AXs was enhanced by enzyme treatment, with low Mw and high A/X ratio associated with elevated NO/iNOS levels in human monocytes compared to water extraction.     

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.     

Influence of pressurised liquid extraction and solid–liquid extraction methods on the phenolic content and antioxidant activities of Irish macroalgae

The efficiencies of pressurised liquid extraction (PLE) and a traditional solid–liquid extraction (SLE) at extracting antioxidant polyphenols from Irish macroalgae Ascophyllum nodosum, Pelvetia canaliculata, Fucus spiralis and Ulva intestinalis were compared. PLE was more effective for extracting polyphenols with acetone/water (80:20); however, when food‐friendly solvents of ethanol/water (80:20) and water were employed, SLE resulted in higher phenolic content in brown macroalgal extracts. For example, the Fucus spiralis SLE water and ethanol/water extracts displayed total phenolic contents (TPCs) of 130.58 ± 2.78 and 142.81 ± 1.77 μg phloroglucinol equivalents (PGE) mg^?1 sample, respectively, compared with TPCs of 90.79 ± 1.16 and 124 ± 6.54 μg PGE mg^?1 sample for the corresponding PLE extracts. All SLE aqueous ethanolic macroalgal extracts possessed higher DPPH radical scavenging abilities (RSA) and ferric reducing antioxidant power (FRAP) than their PLE equivalents . This study indicates that the application of high extraction temperatures (50–200 °C) and pressures (500–3000 psi) used in PLE does not enhance the antioxidant activities of macroalgal extracts relative to SLE extraction. The ability to produce antioxidant food‐friendly macroalgal extracts using SLE could represent significant cost reductions on an industrial scale further enhancing the potential of macroalgal polyphenols to be used in functional food preparations.     

Optimised methodology for the extraction of protein from quinoa (Chenopodium quinoa Willd.)

Quinoa is a highly appreciated Andean pseudo‐cereal and has sparked attention worldwide due to its excellent nutritional value. The protein extraction parameters for defatted quinoa seed meal (DQSM) were optimised in this study. Initially, a Plackett–Burman design was applied to screen the factors displaying a potential effect on the quinoa protein extraction yield (Y %, g soluble protein/100 g total protein) being the main evaluated factors: pH, NaCl concentration, time, temperature, solvent type, particle size and solvent/meal ratio. Four main factors: temperature, solvent/meal ratio, pH and time selected from the screening step were optimised with a central composed design (CCD). The obtained response surface model (RSM) produced a satisfactory fitting of the results (R² = 0.9308). Optimal quinoa protein extraction conditions of 36.2 °C, solvent/meal ratio of 19.6/1 (v/w) and 90 min resulted in a protein yield of 62.1% (9.06 g of protein/100 g DQSM) which closely agree with the predicted value of 62.5%.The model was experimentally validated by extracting the quinoa protein using the optimal conditions revealed by RSM. The optimised conditions could be successfully employed in the design process of protein extraction from quinoa seed meal to obtain optimal yields.     

Improved extraction of disulphide‐rich bioactive proteins from soya hulls: characterisation of a novel aspartic proteinase

Soya hull, an underutilised coproduct of soya processing, was investigated as a source of disulphide‐rich bioactive proteins. A Viscozyme L‐assisted extraction method was developed to improve the yield of extracted proteins. The extracted proteins were identified by MALDI TOF–TOF MS, and the most abundant disulphide‐rich protein among identified proteins was purified and the enzymatic properties were evaluated. The results indicated that the Viscozyme L‐assisted extraction method extracted significantly (P < 0.05) more proteins (39.01%) than did the aqueous method (4.52%). The yield of the purified aspartic proteinase nepenthesin‐1‐like [Glycine max] (GmAPN1K) (the most abundant disulphide‐rich protein) is 570 mg Kg^?1. The specific activity of GmAPN1K was 62.1 U mg^?1 at pH 3.0 and 37 °C. The enzyme was optimally active at pH 3.0 and 55 °C. It was stable within pH range 3.0–10.0 and up to 55 °C, respectively, and was specifically inhibited by pepstatin A.     

Effect of commercial enzymatic preparation with pectolytic activities on conventional extraction and ultrasound‐assisted extraction of oil from grape seed (Vitis vinifera L.)

Conventional solvent extraction (CE) and ultrasound‐assisted extraction (UAE) in hexane for oil from untreated and enzyme‐treated grape seeds were investigated and compared. Among the output power tested (50, 100 and 150 W) in UAE on untreated seeds, UAE at 150 W for 30 min with liquid‐to‐solid ratio 8:1 (v/w) gave oil extraction yield comparable to CE (ca. 14% w/w) for 6 h with liquid‐to‐solid ratio 12:1 (v/w). CE and UAE at 150 W did not influence the fatty acid profiles of oil. CE oil was found to be the most oxidised. The enzymatic treatments (2, 4 and 6 g per 100 g seeds of Rapidase^® Expression) prior to CE enhanced by 2.5% of the oil yield. Enzymatic treatments higher than 2 g per 100 g seeds increased relative value of some fatty acids both in CE and UAE. Enzymatic pretreatment from 2 to 4 g per 100 g seeds significantly improved some physicochemical parameters of oil quality when extracted by CE, but not by UAE.     

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.     

Improved Extraction and Quality Characterization of Water‐Soluble Polysaccharide from Gamma‐Irradiated Lentinus edodes

Gamma irradiation was applied to the improved extraction of water‐soluble polysaccharides (WSPs) from dried Lentinus edodes. Irradiation provided a dose‐dependent increase in extraction yield (0 kGy, 2.01%; 7.5 kGy, 4.03%; 15 kGy, 7.17%) and purity (0 kGy, 78.8%; 7.5 kGy, 83.1%; 15 kGy, 85.6%) of the WSPs from hot‐water extraction. The effect of irradiation was evident in the degraded microstructures and reduced molecular weights of the WSPs. However, nuclear magnetic resonance, Fourier‐transform infrared, and X‐ray diffraction spectroscopic analyses provided comparable structures of WSPs from nonirradiated and irradiated samples. UV–visible spectra showed a dose‐dependent decline in intensity, but an improvement in thermal properties of the WSPs from the irradiated mushroom samples was observed.     

Microwave‐assisted extraction and antioxidant activity of star anise oil from Illicium verum Hook.f

In this study, microwave‐assisted extraction with ethanol (MAEE) of star anise oil from Illicium verum Hook.f. has been optimised by response surface methodology (RSM). A maximum yield of star anise oil was obtained at an optimum condition: the ratio of solvent to sample 17 mL g^?1, extraction time 16 min and microwave power 505 W. Accordingly, the highest yield of star anise oil was about 24.98%, which was much higher than that of steam distillation (SD), 7.17%. Oxygenated organic compounds in representative of trans‐anethole are a major component in star anise oil, nearly 94.21% for SD and 86.66% for MAEE, identified and determined by GC‐MS. The oils extracted by SD and MAEE both have strong antioxidant activities that were demonstrated by the DPPH and ABTS assays.     

Optimisation of the extraction conditions of natural colourant carthamin from safflower (Carthamus tinctorius L.) by response surface methodology

Alkali‐solution and acid‐isolation method (ASAI) and aqueous two‐phase system separation method (ATSS) have been reported to extract natural colourant carthamin from Carthamus tinctorius. In this study, these two methods were compared based on the optimisation results of extraction conditions by response surface methodology. In ASAI, the maximum extraction yield reached 0.779% at pH value of potassium carbonate solution of 11.16, ratio of potassium carbonate solution to raw material of fifteen and extraction time of 18 min, while 2.652% was achieved with concentration of acetone of 58%, ratio of acetone solution to raw material of twenty‐three and extraction time of 41 min in ATSS. From the point of view of extraction yield, ATSS had more superiority than ASAI. However, more pure carthamin was provided in ASAI according to HPLC assay. The obtained results in our experiments could be utilised for further researches of carthamin.     

Yield,characteristics and composition of banana juice extracted by the enzymatic and mechanical methods

A comparative study of the enzymatic and mechanical banana juice extraction methods and the respective juices produced was carried out using Kayinja bananas (ABB genotype) imported from Uganda. In the enzymatic extraction process, macerated ripe banana pulp was incubated with a commercial enzyme preparation (Pectinex Ultra SP‐L) at 50 °C for 2 h. In the mechanical extraction process the ripe banana pulp was mixed with stretched strips of polythene and worked with a dough mixer at room temperature for 20 min (on average) until the juice appeared. Significantly (p < 0.05) higher ‘pure’ juice yield (604 g kg^?1 pulp) was obtained with the enzymatic method than with the mechanical method (541 g kg^?1 pulp). However, adding water to the spent pulp from the mechanical process and extracting dilute juice improved the juice yield to 757 g kg^?1 pulp. The enzyme‐extracted juice had significantly (p < 0.05) higher soluble solids, titratable acidity, fructose, glucose, total nitrogen, density and mineral potassium. However, the mechanically extracted juice had significantly higher sucrose, pH and viscosity. Although the mechanical extraction process suffers from occasional juice extraction failures, it offers an opportunity to extract banana juice without excessive energy expenditure, and the juice produced is wholesome with a superior flavour to that produced by the enzymatic method. © 2002 Society of Chemical Industry     

Optimisation of extraction conditions and thermal properties of protein from the Andean pseudocereal cañihua (Chenopodium pallidicaule Aellen)

Response surface methodology (RSM) was used to optimise alkaline protein extraction from cañihua grain meal as to maximise protein extraction yield. Different factors (temperature, extraction time, solvent/meal ratio, pH and NaCl molar concentration) were screened, and their significant influence on the extracted protein yield was evaluated. The first four factors were selected and studied by RSM using a central composite design (CCD). The obtained model produced a satisfactory fitting of the results (R² = 0.801). Optimal cañihua protein extraction conditions corresponded to a temperature of 21 °C, time extraction of 5 min, solvent/meal ratio of 37/1 (v/w) at pH 10 resulting in a protein yield of 80.4 ± 1.3%, which closely agree with the predicted value of 81.4%. Moreover, protein degradation was studied via differential scanning calorimetry (DSC) obtaining a denaturation temperature of 93.4 °C and an enthalpy value of 1.22 ± 0.05 J g^?1. These results are interesting from a technological point to help in designing an optimal protein extraction process and cañihua food processing strategies.     

Production and stability of water‐dispersible astaxanthin oleoresin from Phaffia rhodozyma

The process of extracting the astaxanthin oleoresin from pretreated Phaffia rhodozyma cells was optimised using a Box‐Behnken response surface design. Microwaving the cells at 105 W for 1 min followed by ethyl acetate extraction was the best pretreatment, and the optimal extraction conditions were 65 °C for 24 min using a solvent–solid ratio of 19:1. The order of the ability to disperse the astaxanthin oleoresin was propylene glycol> Tween 80 > Tween 20 > α‐cyclodextrin, β‐cyclodextrin. It was determined that the degradation of the colour of the water‐dispersible oleoresin followed a first‐order kinetics model. The greatest stability was observed at pH 4 and at the lowest temperature evaluated (40 °C). The thermal degradation of the pigment occurs in two steps, the first one from 0 to 1.5 h, with an E_aI = 10.31 kJ mol^?1, and the second one from 1.5 to 5 h, with an E_aII = 30.06 kJ mol^?1     

Discrimination of Kyoho grape (Vitis labruscana) skin,seed and flesh antioxidant activities by solvent extraction: application of advanced chemometrics

Grape skin, seed and flesh, a potential source of bioactive compounds, were investigated to discriminate Kyoho skin, seed and flesh antioxidant activities by solvent extraction using chemometrics, including multivariate, discriminant analysis (DA) and hierarchical cluster analysis (HCA). Multivariate analysis (Wilk's Λ = 0.02 × 10^-4, P < 0.01) explained the discrimination behaviour of phenolics and antioxidants by different solvents. Moreover, DA with three discrimination functions (DFs) and HCA with three well-defined clusters (clusters 1 to 3) further demonstrated the differences and/or similarities among the solvents. Solvent I (75% ethanol: water) exhibited the different extraction process over the solvents IV (water) and III (acetone: water). Quercetin (39.25 mg kg⁻¹), epicatechin (53.08 mg kg⁻¹) and gallocatechin gallate (1.28 mg kg⁻¹) were the major phenolic compounds in Kyoho skin, seed and flesh extracts, respectively. These further confirmed the chemometric approach that could be used to discriminate solvents. Therefore, these findings suggested the application of chemometrics in extraction studies to understand the role of solvents and high recovery of grape bioactive compounds.     

A rapid method for the measurement of Leucaena spp proanthocyanidins by the proanthocyanidin (butanol/HCl) assay

Proanthocyanidin (PA) extraction, sample preparation and proanthocyanidin assay (butanol/HCl) reaction conditions were evaluated for measuring PA in Leucaena spp leaf material. The optimal conditions for extracting PA from leaf tissue are described, with short sequential sonications in 70% aqueous acetone being as efficient as prolonged sequential mechanical agitation. In methanol–based extracts, after back extraction to remove pigments, increasing the water content of the reagent/sample matrix suppressed colour development. The addition of low concentrations of Fe³⁺ to the butanol/HCl reagent enhanced colour yield, but higher Fe³⁺ concentrations suppressed colour development. The presence of ascorbic acid in the sample extract was shown to increase colour development. Varying the reagent: sample extract ratio from 4:1 to 6:1 significantly decreased colour yield, but neither ratio was different from 5:1. Optimum conditions for the PA assay were as follows: a water content of 8%, the omission of Fe³⁺, a reagent: sample extract ratio of 5:1 and the addition of ascorbic acid to the stock PA standard solution to match that contributed by the extract in the final mixture. Sample preparation procedures, using back extraction to remove pigments and non-PA phenolics with diethyl ether and ethyl acetate, respectively, were time-consuming and subject to PA losses. The measurement of PA directly in the 70% aqueous acetone extract eliminated these PA losses, but the PA assay required additional optimisation for direct analysis of crude acetone extracts. In the final optimised procedure, PA was extracted by sequential sonication with 70% aqueous acetone containing 5·26 mM sodium metabisulphite as the antioxidant. These extracts were directly analysed by the butanol/HCl reaction using a reagent: sample extract ratio of 5:1, the omission of Fe³⁺ from the butanol/HCl reagent and the addition of sodium metabisulphite to match that contributed by the extract. This produced consistent linear calibration curves over the range 25–1000 μg PA with an average recovery of 101%. © 1998 Society of Chemical Industry.     

Optimisation of acid extraction of pectin from sweet potato residues by response surface methodology and its antiproliferation effect on cancer cells

The response surface methodology was employed to study the acid extraction of pectin from sweet potato residues. The effects of extraction temperature, extraction time, solution pH and liquid/solid ratio on yield and galacturonic acid content of pectin were investigated. Experimental data were fitted to quadratic polynomial models and analysed using appropriate statistical methods. The determined optimum conditions were extraction temperature 93 °C, extraction time 2.2 h, solution pH 1.7 and liquid/solid ratio (v/w) 30:1. Under these conditions, the experimental extraction yield and galacturonic acid content of pectin were 5.09% and 70.03% (w/w), which were in good agreement with predicted values, 5.08% and 69.40%, respectively. In addition, sweet potato pectin exhibited remarkable antiproliferation effects on human colon cancer cells HT‐29 and human breast cancer cells Bcap‐37 by 46.64% and 42.64% at 1.00 mg mL^?1 separately, indicating that it could potentially be used as a natural supplement in functional foods.     

Optimisation of ultrasound extraction for flavonoids from semen astragali complanati and its identification by HPLC‐DAD‐MS/MS

The optimisation of ultrasound extraction of semen astragali complanati flavonoids was studied by measuring characteristic absorbance at 266 nm as the response and using response surface methodology (four‐variable, three‐level Box–Behnken design, BBD) in this article. The optimal conditions were obtained as 52 °C, 34 min, 26:1 (mL:g) and 100 mesh (0.120–0.150 mm) for extraction temperature, extraction time, solvent‐to‐sample ratio as well as particle size, respectively. Under these conditions, validation experiments were carried out and the experimental value of A₂₆₆ was 0.9907 ± 0.032 (n = 3), which corresponded to an experimental extraction yield of 7.08%. Compounds in the extracts obtained with the optimum extraction conditions were identified by high‐performance liquid chromatography coupled with diode array and mass spectrometry detectors (HPLC–DAD–MS). Among the 14 compounds that were tentatively identified in the extracts according to their ultraviolet‐visible spectroscopy, mass spectrometry and related literature reports, four were reported for the first time.     

Improvement of bixin extraction yield and extraction quality from annatto seed by modification and combination of different extraction methods

Bixin from annatto seed was extracted by submerging the seeds in acetone and by combined extractions using sodium hydroxide and soybean oil in the dark to improve extraction yield and reduce content of volatile compounds in annatto extracts. The exclusion of light from acetone extraction did not significantly improve bixin extraction yield (68.5%) compared to the process carried out under daylight (67.3%), but it remarkably reduced contents of toluene and m‐xylene in annatto extracts. Combined extraction using sodium hydroxide solution at 50 °C for 40 min and soybean oil at 100 °C for 20 min resulted in very low level of volatile compounds. Significantly higher extraction yield (53.7%) could be achieved by such a process as compared to a single extraction sodium hydroxide (31.8%) or soybean oil (42.9%) alone. In conclusion, the exclusion of light from acetone extraction and combined extraction significantly reduced concentration of undesirable volatile compounds. The combined extraction significantly improved bixin yield compared to the original extraction methods.     

Effect of extraction parameters on the carotenoid recovery from tomato waste

Tomato waste is an important source of natural carotenoids. This study was carried out to assess the extractability of tomato waste carotenoids in different organic solvents and to optimise the extraction parameters (type of solvent, extraction time, temperature and extraction steps) for maximum yield. Among other solvents, we tested a new environmentally friendly one, ethyl lactate, which gave the highest carotenoid yield (243.00 mg kg^?1 dry tomato waste) at 70 °C, compared to acetone (51.90 mg kg^?1), ethyl acetate (46.21 mg kg^?1), hexane (34.45 mg kg^?1) and ethanol (17.57 mg kg^?1). The carotenoid recovery was significantly (P < 0.05) affected by the number of extraction steps and temperature in all solvents. Mathematic equations predicted rather satisfactorily (R² = 0.89–0.93) the rate of carotenoid extraction in the above‐mentioned solvents. Carotenoid concentration increased with time, approaching a quasi‐saturated condition at approximately 30 min of extraction.