Ultrasound‐assisted extraction of polyphenols from potato peels: profiling and kinetic modelling

Ultrasound‐assisted extraction (UAE) at 33 and 42 kHz has been investigated in the extraction of polyphenols from peels of two potato varieties, cream‐skinned Lady Claire (LC) and pink‐skinned Lady Rosetta (LR), commonly used in snack food production. Extraction efficacy between the UAE‐untreated (control) and the UAE‐treated extracts was assessed on the total phenolic content and antioxidant capacities (DPPH and FRAP). Application of UAE showed significantly higher recovery of phenolic compounds compared to solid–liquid extraction process alone. Lower ultrasonic frequency (33 kHz) was more effective in recovering polyphenols compared to 42 kHz ultrasonic treatment. The liquid chromatography‐tandem mass spectrometry revealed that chlorogenic acid and caffeic acid were the most prevalent phenolics in LR peels, whereas caffeic acid was dominant in LC peels. Peleg's equation showed a good correlation (R² > 0.92) between the experimental values and the predicted values on the kinetics of UAE of phenolic compounds.     

In vitro inhibitory effects of cranberry bean (Phaseolus vulgaris L.) extracts on aldose reductase, α‐glucosidase and α‐amylase

The in vitro inhibitory activities of different seed extracts prepared from cranberry bean mutant SA‐05 and its wild‐type variety Hwachia against aldose reductase, α‐glucosidase and α‐amylase were examined. The results indicated that the polyphenolics‐rich extracts obtained using 800 g kg^?1 methanol and 500 g kg^?1 ethanol demonstrated inhibitory activities against aldose reductase (IC₅₀ of 0.36–0.46 mg mL^?1) and α‐glucosidase (IC₅₀ of 1.32–1.94 mg mL^?1). The 500 g kg^?1 ethanol extracts also showed α‐amylase inhibitory activities (IC₅₀ of 70.11–80.22 μg mL^?1). Subsequent extracts, prepared further with NaCl and H₂O from precipitates of 800 g kg^?1 methanol or 500 g kg^?1 ethanol extracts, exhibited potent α‐amylase inhibitory activities (IC₅₀ of 17.68–38.68 μg mL^?1). A combination of 500 g kg^?1 ethanol extraction plus a subsequent H₂O extraction produced highest polyphenolics and α‐amylase inhibitors. The SA‐05 α‐amylase inhibitor extracts showed greater inhibitory activities than that of Hwachia. Thus, cranberry bean mutant SA‐05 is an advantageous choice for producing anti‐hyperglycaemic compounds.     

Supercritical CO2 oil extraction from Chinese star anise seed and simultaneous compositional analysis using HPLC by fluorescence detection and online atmospheric CI‐MS identification

BACKGROUND: Supercritical CO₂ was utilised to extract Chinese star anise seed oil (CSASO), and a three‐level Box–Behnken factorial design from response surface methodology was applied to optimise the extraction conditions, including pressure, temperature and amount of modifier (ethanol). The compositional analysis of fatty acids in CSASO was performed by HPLC with fluorescence detection using 2‐(11H‐benzo[a]carbazol‐11‐yl)‐ethyl‐4‐methylbenzenesulfonate (BCETS) as labelling reagent. Identification was carried out by online atmospheric chemical ionisation–mass spectrometry. RESULTS: The optimum extraction conditions were as follows: extraction pressure, 27.72 MPa, extraction temperature, 46.22 °C, and amount of modifier, 8.58 vol.%. The experimental result showed that the maximum extraction yield was 25.31 ± 0.22% (w/w) under the conditions proposed. The compositional analysis indicated that CSASO mainly contained C18:2, C18:1, C18:3, C20:4, C16, C18 and C20 fatty acids. CONCLUSION: In this study, a fast, simple and high‐efficiency supercritical technique for extracting oil from Chinese star anise seed was developed. Simultaneous determination of fatty acids in CSASO using BCETS as the labelling reagent with HPLC fluorescence detection and online mass spectroscopy identification has been successfully achieved. Copyright © 2010 Society of Chemical Industry     

Microwave‐assisted extraction in goji berries: effect on composition and bioactivity,evaluated through conventional and nonconventional methodologies

This study aimed to evaluate the effect of microwave‐assisted extraction (MAE) parameters on the composition and bioactivity of goji (Lycium barbarum) extracts. Extracts were obtained under a central composite design combination of experimental conditions, and characterised through HPLC‐DAD; their bioactive capacity was ascertained for antimicrobial and antioxidant capacity, the later by spectrophotometric [2,2‐azinobis (3‐ ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt‐radical scavenging activity assay – 413–748 mg ascorbic acid equivalents/100 g DW and oxygen radical absorbance capacity – 1901–2292 mg trolox equivalents/100 g DW] and electrochemical (DNA‐based sensor – 3571–6602 mg ascorbic acid/100 g DW) methods. The quantitative profile of phenolic compounds was strongly dependent on MAE conditions. Significant correlations were found between the presence of several flavonoids and solvent composition, as well as between phenolic acids with methoxy group and the response to DNA‐based sensor. Results may improve targeted extractions for specific compounds, leading to the achievement of extracts richer in antioxidant capacity, as well as in the tailoring of the biosensor response sensitivity to the composition of the extracts under analysis.     

Optimisation of red pepper seed oil extraction using supercritical CO2 and analysis of the composition by reversed‐phase HPLC‐FLD‐MS/MS

Oil extractions from red pepper seed were performed by supercritical CO₂. Three‐level Box–Behnken factorial design (BBD) from response surface methodology (RSM) was applied to optimise the main extraction conditions including pressure, temperature and concentration of modifier (ethanol). The optimum conditions were as follows: extraction pressure, 27.17 MPa; extraction temperature, 47.67 °C; and the added concentration of modifier, 8.11 vol.%. Under the optimum conditions, the oil yield of 18.4% was obtained, which was well matched with the predicted yield. A simple, stable and sensitive method for the simultaneous determination of saturated and unsaturated free fatty acids in extracted oils using 2‐(11H‐benzo[a]carbazol‐11‐yl)‐ethyl‐4‐methylbenzenesulfonate (BCETS) as labelling reagent with fluorescence detection has been developed. All of free fatty acids (FFA) were found to give a linear response with correlation coefficients of >0.9991. The detection limits at a signal‐to‐noise ratio (S/N) of three are in the range of 19.06–41.19 fmol. This method should have powerful potential for the trace analysis of short‐ and long‐chain FFA from edible oils, foodstuff and other complex samples.     

Presence of two forms of methylated (–)‐epigallocatechin‐3‐gallate in green tea

Crude catechins extract from Chinese green tea were fractionated using Sephadex LH‐20 column chromatography. The fraction containing (–)‐epigallocatechin‐3‐gallate (EGCG) was then subjected to a semipreparative high‐performance liquid chromatography (HPLC). Using a mobile phase of water : dimethyl formamide : methanol : acetic acid (157 : 49 : 2 : 1 v/v/v/v( the mixture of two methylated catechins was separated and isolated. According to mass spectrometry (MS) and nuclear magnetic resonance (¹H‐NMR) date, these compounds were identified as (–)‐epigallocatechin‐3‐(3‐O‐methylgallate) and (–)‐epigallocatechin‐3‐(4‐O‐methylgallate).     

Optimisation of ultrasonic‐assisted extraction of polyphenols from apple peel employing cellulase enzymolysis

Cellulase enzymolysis extraction with ultrasonic‐assisted technology was applied for polyphenols extraction from apple peel, and response surface methodology was used to optimise the conditions of polyphenols extraction. Efficiency of extraction was optimised by measuring total polyphenol content and three individual polyphenols. Three independent variables that were taken into consideration were extraction time (X₁), extraction temperature (X₂) and enzyme amount (X₃). The statistical analysis indicated that extraction time and the quadratic of X₁ had significant effects on the yields. The mathematical model had been developed adequately describing the ranges of the experimental parameters studied and provided a statistically accurate prediction of the optimum yield. A high correlation of the quadratic polynomial mathematical model was gained. The optimal extraction conditions of polyphenols were determined as follows: extraction time of 37 min, extraction temperature of 37 °C and enzyme amount of 2500 U g^?1, which was agreed closely with the predicted value.     

Isolation,purification and characterisation of angiotensin I‐converting enzyme–inhibitory peptides derived from catfish (Clarias batrachus) muscle protein thermolysin hydrolysates

The angiotensin I‐converting enzyme (ACE)‐inhibitory activities of catfish (Clarias batrachus) muscle protein hydrolysates were investigated. Thermolytic digests of C. batrachus sarcoplasmic and myofibrillar proteins exhibited inhibitory activity towards ACE and were purified with the aim of ultrafiltration, gel filtration and reversed‐phase high‐performance liquid chromatography (RP‐HPLC). The amino acid sequences of hydrolysates with the highest ACE‐inhibitory activities were determined using electrospray quadrupole time‐of‐flight tandem mass spectrometry (ESI‐TOFQ MS/MS). The sequences of GPPP (IC₅₀ = 0.86 μm ) and IEKPP (IC₅₀ = 1.2 μm ) corresponding to the fragments 986–989 and 441–445 of myosin‐I heavy chain were identified for the sarcoplasmic and myofibrillar protein hydrolysates, respectively. Peptide GPPP exhibited a mixed‐type inhibition whereas peptide IEKPP could only bind to the active sites of ACE. The results demonstrate that hydrolysates of C. batrachus muscle proteins obtained by thermolysin may contain bioactive peptides.     

Qualitative and quantitative analysis of the major phenolic compounds as antioxidants in barley and flaxseed hulls using HPLC/MS/MS

BACKGROUND: Both qualitative and quantitative analyses of the major phenolic compounds in barley and flaxseed hulls were conducted using reverse phase high‐performance liquid chromatography coupled with photodiode array detection and quadrupole time‐of‐flight mass spectrometry. RESULTS: Ferulic acid, p‐coumaric acid, vanillic acid and vanillin were identified and quantified in four barley hull samples. Four ferulate dehydrodimers were also detected. The phenolic compounds of flaxseed hull were distinct from those of barley hull. Three flaxseed hull samples varied significantly (P < 0.05) in their contents of secoisolariciresinol diglucoside (16.38–33.92 g kg^?1), coumaric acid glucoside (35.68–49.22 g kg^?1) and ferulic acid glucoside (5.07–15.23 g kg^?1). The phytochemical profiles of co‐extracts featured the major phenolic compounds from both barley and flaxseed hulls. The total phenolic content and 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging capacity varied significantly (P < 0.05) among different varieties of flaxseed and barley hulls. CONCLUSION: As agricultural by‐products, barley and flaxseed hulls may be utilised as potential sources of functional food ingredients through extraction and concentration of the phytochemicals identified above. Copyright © 2012 Society of Chemical Industry     

Quantitative UPLC‐MS/MS analysis of chlorogenic acid derivatives in antioxidant fractionates from dandelion (Taraxacum officinale) root

While qualitative studies have identified chlorogenic acids in antioxidant extracts, particularly ethyl acetate‐derived extracts, of Taraxacum officinale, quantitative analysis of these phenolic compounds remains largely unreported for this species. In this study, bioactivity‐guided fractionation of an antioxidant crude ethyl acetate extract (DPPH = 295.481 ± 0.955 mg TE g^?1 extract) from T. officinale root resulted in a number of reverse‐phase fractions that demonstrated high antioxidant activity (DPPH = 1058.733–1312.136 mg TE g^?1 extract), stronger than that of the synthetic antioxidant Trolox^®. UPLC‐MS/MS screening of these fractions for the presence of selected mono‐ and di‐caffeoylquinic acids revealed large quantities of 1,5‐dicaffeoylquinic acid present in several fractions (853.052–907.324 μg mg^?1), respectively. Due to the antioxidant potency and high levels of 1,5‐dicaffeoylquinic acid observed in these fractions, it was concluded that specifically this chlorogenic acid derivative is a major contributor to the antioxidant efficacy of dandelion root.     

Antibiofilm formation and anti‐adhesive (to HEp‐2 cells) effects of rosemary water extract against some food‐related pathogens

The present work aimed to determine the bioactive compounds in two rosemary water extracts (RWE1 and RWE2) and to assess their antimicrobial, anti‐adhesive and antibiofilm potentials against the food‐related Bacillus and Pseudomonas species at concentrations; 4, 8, 12, 16 and 20 mg mL^?1. Phenolic compounds and isoflavones in the RWEs were determined using HPLC. The concentrations of most bioactive compounds of RWE1 (benzoic, ellagic, gallic and rosmarinic acids, daidzein and genistein) were higher than that of RWE2. The MIC₉₀ of RWE1 and RWE2 against all tested bacteria was 12 and 16 mg mL^?1, respectively. The anti‐adhesive and antibiofilm doses were higher than MIC₉₀. RWE1 and RWE2 showed potential reduction in the bacterial cell adhesion to HEp‐2 cells – 17.5–64.7 and 12.2–52.9%, respectively. In conclusion, this study emphasises the effective use of RWE as a natural anti‐adhesive and antibiofilm agent against Bacillus and Pseudomonas, without difficult extraction procedure.     

Anti‐inflammatory properties of high pressure‐assisted extracts of Grifola frondosa in lipopolysaccharide‐activated RAW 264.7 macrophages

The aim of this study was to determine the in vitro anti‐inflammatory properties of the shake extract (SE) and the high pressure‐assisted extract (PE) of the mycelia of Grifola frondosa in a lipopolysaccharide‐stimulated RAW 264.7 macrophage model. The content of total polysaccharides and β‐glucans of PE at 600 MPa (PE‐600) was 41.2 and 6.2 mg g^?1 dry weight, respectively, which were significantly higher than SE extracts. The results showed that treatment with 500 μg mL^?1 of PE by 600 MPa (PE‐600) did not reduce RAW 264.7 cell viability but did significantly inhibit the production of LPS‐induced NO, PGE₂ and intracellular ROS. The PE‐600 inhibited the activation of NF‐kB and then reduced the production of LPS‐induced TNF‐α, IL‐6 and IL‐1β in a dose‐dependent manner. Thus, the PE could be used as an alternative extraction method for improving the extraction efficacy of G. frondosa and serve as an alternative source of anti‐inflammatory agents.     

Optimisation of microwave‐assisted extraction of prune (Prunus domestica) antioxidants by response surface methodology

Optimal conditions for microwave‐assisted extraction (MAE) of total phenols (TP), epicatechin gallate and antioxidant activity from prune (Prunus domestica), rejected in transformation process of plum to prune, were determined by response surface methodology. The central composite design was used to study the effects of three independent variables: microwave power, irradiation time and solvent polarity on the TP, epicatechin gallate and antioxidant activity. Epicatechin gallate was identified as a major phenolic compound in prune extract by RP‐HPLC. Microwave power and irradiation time significantly affected all responses (P < 0.01). The highest TP (598.89 mg GAE/100 g prune) was obtained using water as an extraction solvent at 500 W, during 115 s. However, the optimal conditions for epicatechin gallate extraction were ethanol 80%, 435 W and 120 s. MAE is more efficient than conventional extraction method to obtain TP from prune. The experimental values were reasonably close to the predicted values confirming the validity of the predicted models.     

Comparison of ginsenosides in radix and rhizome of wild Panax species using LC‐ELSD and LC‐Q‐TOF‐MS

High‐performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) and quadrupole time‐of‐flight mass spectrometry (Q‐TOF‐MS) were used for qualitative and quantitative analysis of wild Panax species, especially wild P. vietnamensis, which is an important medicinal plant. We determined the types and concentrations of ginsenosides in radix and rhizome of wild P. vietnamensis. Identification of ginsenosides was achieved using Q‐TOF‐MS; concentrations were determined by ELSD. The most abundant ginsenosides in wild Vietnamese ginseng were of the ocotillol type, accounting for more than 50% of the total. Compared to the rhizome, the radix had 31% higher ginsenoside content due to variation in protopanaxatriol‐type ginsenoside contents. We also found an unusual difference in the chromatograms of the two parts of wild P. vietnamensis. This difference did not appear in other wild species such as P. ginseng and P. quinquefolius. Our study provides an opportunity for further in‐depth study of the distinctive characteristics of P. vietnamensis.     

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     

Screening grape seeds recovered from winemaking by‐products as sources of reducing agents and mammalian α‐glucosidase and α‐amylase inhibitors

Grape seeds collected from vinification of various grape varieties were extracted by supercritical CO₂ for oil recovery. The defatted residues thus obtained were considered as a re‐utilisable co‐product and assessed for phenolic content, reducing capacity and inhibitory activities against mammalian α‐amylase and α‐glucosidase enzymes. Supercritical CO₂ treatment led to higher recovery of anthocyanins. Reducing capacity of phenolic extracts reached up to ~2200 mmolFe(II) kg^?1, much higher than that of various natural phenolic sources. The anthocyanin‐rich extracts showed the highest inhibitory effectiveness towards α‐glucosidase (I₅₀ value equal to ~40 μg gallic acid equivalents (GAE)/mL ~ half than acarbose). Inhibitory effectiveness towards α‐amylase activity was similar among grape varieties, with I₅₀ values comparable to that of acarbose and correlated with proanthocyanidin contents. These results could pave the way for an efficient processing of grapes, including cascade processes, namely: winemaking, oil extraction from recovered grape seeds and phenolic extraction from defatted grape seeds as potential cost‐effective nutraceuticals.     

Supercritical carbon dioxide extraction for identification of adulteration of black pepper with papaya seeds

Supercritical fluid extraction (SFE) using carbon dioxide was used to detect the adulteration of black pepper powder with ground papaya seed. Thin‐layer chromatography analysis of the SFE extracts showed a fluorescent band at 366 nm at R_f 0.172 that proved to be a promising marker for the presence of papaya seed powder in black pepper powder even at a level of 20 g kg^?1. The straight‐chain aldehydes n‐nonanal, n‐decanal and n‐dodecanal were tentatively identified by gas chromatography–mass spectrometry analysis as components of this fluorescent marker and were not present in black pepper extracts. Copyright © 2003 Society of Chemical Industry     

Antioxidant and anticancer capacity of saponin‐enriched Carica papaya leaf extracts

The papaya (Carica papaya) leaf (PL) contains high levels of saponins and polyphenolic compounds, and historically, it has been used as a folk medicine for numerous ailments, including cancer. PL is traditionally prepared by hot water extraction; however, optimised extraction conditions have not been assessed. This study optimised conditions for the extraction of saponins from PL and assessed their antioxidant capacity and antipancreatic cancer activity. Optimisation was achieved using response surface methodology. Saponins and total phenolic compounds were assessed for their antioxidant, free radical scavenging, ion‐reducing capacity, and antipancreatic cancer activity. Optimal aqueous extraction conditions were 85 °C, 25 min. and a water‐to‐leaf ratio of 20:1 mL g^?1. Ethanol extracts demonstrated higher antioxidant, free radical scavenging and ion‐reducing capacity, as well as antipancreatic cancer activity. This study revealed that the PL contains numerous bioactive compounds, with significant anticancer activity warranting further studies on the isolation and characterisation of individual bioactive compounds from the PL.     

Antioxidant activity and phenolic content of pressurised liquid and solid–liquid extracts from four Irish origin macroalgae

The efficiency of solid–liquid extraction (SLE) and pressurised liquid extraction (PLE) for the recovery of antioxidant and polyphenols from the Irish macroalgae, Fucus serratus, Laminaria digitata, Gracilaria gracilis and Codium fragile, was assessed using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays and the Folin–Ciocalteu total phenol content (TPC) assay. Fucus serratus had TPC and antioxidant activities thirty times higher than the other species. Solid–liquid extraction cold water (CW_SLE) had the highest TPC (81.17 μg GAE mg^?1 sample) derived from F. serratus, compared with the TPC of 61.12 μg GAE mg^?1 sample for the corresponding PLE extract. For both SLE and PLE extracts, low TPC levels were observed in L. digitata, G. gracilis and C. fragile. The majority of SLE extracts possessed higher FRAP and DPPH activities compared with their PLE counterparts. This study indicates that the high temperatures and pressures in PLE did not enhance the antioxidant activities relative to conventional SLE extraction.     

Original article: Extraction of lipid from scallop (Patinopecten yessoensis) viscera by enzyme‐assisted solvent and supercritical carbon dioxide methods

In the present study, lipid was extracted from scallop (Patinopecten yessoensis) viscera by using the enzyme‐assisted solvent method and the supercritical carbon dioxide (SC‐CO₂) method. Soxhlet extraction with ethyl ether produced a yield of 23.7 ± 0.6 g of lipid 100 g^?1 of dry matter. Enzyme‐assisted solvent extraction allowed recovering 60.6 ± 1.5% of P. yessoensis viscera lipid from the samples treated with papain, whereas a lipid recovery rate of 78.3 ± 0.6% was achieved by SC‐CO₂ extraction. The lipid extracted was divided into the unsaponifiable fraction (sterol) and the saponifiable fraction (fatty acid) and analysed by gas chromatography mass spectrometry. Results indicated that the fatty acid composition and sterol composition for lipids extracted by different methods were slightly different. Eicosapentaenoic acid and docosahexaenoic acid were dominant polyunsaturated fatty acids accounting for 35–40% of the total fatty acid.