Optimization of extraction of phenolic compounds from flax shives by pressurized low-polarity water

Optimization of Antioxidant and Skin-Whitening Compounds Extraction Condition from Tenebrio molitor Larvae (Mealworm)

Skin-whitening ingredients are a very important part of the development of functional cosmetics and a wide variety of raw materials are used. Tyrosinase is a key enzyme in the animal melanogenic pathway that is the rate-limiting step for the production of melanin. Several synthetic and naturally occurring tyrosinase inhibitors have been studied for skin-whitening. The development of natural agents is becoming more important due to the disadvantages of synthetics such as high cytotoxicity, insufficient penetration power, and low activity. The purpose of this study was to evaluate the total phenol content (TPC), antioxidant, and tyrosinase inhibition activity of mealworm (Tenebrio molitor larvae) extract, and the subsequent optimization of the extraction condition using statistically-based optimization. The major extraction variables extraction temperature, time, and ethanol concentration were optimized using response surface methodology (RSM). The results showed that optimum extraction temperature of 88.1 °C, extraction time of 43.7 min, and ethanol concentration of 72.0 v/v%, provided the predicted maximum levels of total phenolic compounds (TPC) of 5.41 mg GAE/g dry weight (DW) and tyrosinase inhibition activity (TIA) of 82.4%. From the validation experiment, 5.61 ± 0.2 mg GAE/g dry weight (DW), tyrosinase inhibition of 79.6 ± 3.3%, and radical scavenging activity of 91.8 ± 5.1 μg/mL were found and showed to be very similar to the predicted values. These results suggest that mealworm has great potential as a source of bioactive compounds which could be used as cosmetics, food, and pharmaceutical agents.

Subcritical water extraction, UPLC-Triple-TOF/MS analysis and antioxidant activity of anthocyanins from Lycium ruthenicum Murr

In this work, it has been developed an efficient method for extraction of anthocyanin from Lycium ruthenicum Murr. and the antioxidative activities research. Subcritical water extraction was investigated as a green technology for the extraction of anthocyanin from L. ruthenicum. Several key parameters affecting extraction efficiency were investigated and optimized by response surface methodology (RSM) combined with Box-Behnken design (BBD). The optimum extraction conditions and the desirability of model were the time of extraction = 55 min and the flow rate was 3 mL/min at 170 °C. At this operating condition, the content of anthocyanin was high to 26.33%. Subcritical water extraction was more efficient than using hot water or methyl alcohol for the extraction of anthocyanin. The composition of anthocyanins from L. ruthenicum has been investigated by high-performance liquid chromatography with diode array detector (HPLC-DAD) and Ultra Performance Liquid Chromatography-Triple-Time of Flight Mass Spectrometer (UPLC-Triple-TOF/MS). Seven anthocyanins have been detected, all of which were identified and quantified. Furthermore, the anthocyanins extracted by SWE showed significantly better antioxidant activity than the anthocyanins extracted by hot water or methyl alcohol according to DPPH and ABTS assay. SWE with significantly higher anthocyanin and antioxidant activity were achieved compared to conventional methods.

Optimization of Phenolic Compounds Extraction from Flax Shives and Their Effect on Human Fibroblasts

The goal of this study was to evaluate the most effective technique for extraction of phenolics present in flax shives and to assess their effect on human fibroblasts. Flax shives are by-products of fibre separation, but they were found to be a rich source of phenolic compounds and thus might have application potential. It was found that the optimal procedure for extraction of phenolics was hydrolysis enhanced by the ultrasound with NaOH for 24 h at 65°C and subsequent extraction with ethyl acetate. The influence of the flax shives extract on fibroblast growth and viability was assessed using the MTT and SRB tests. Moreover, the influence of flax shives extract on the extracellular matrix remodelling process was verified. The 20% increase of the viability was observed upon flax shives extract treatment and the decrease of mRNA collagen genes, an increase of matrix metalloproteinase gene expression, and reduction in levels of interleukin 6, interleukin 10, and suppressor of cytokinin signaling 1 mRNA were observed. Alterations in MCP-1 mRNA levels were dependent on flax shives extract concentration. Thus, we suggested the possible application of flax shives extract in the wound healing process.

Development of a subcritical water extraction approach for trace analysis of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in poultry tissues

Subcritical water extraction was investigated as a novel and alternative technology for the separation of trace amounts of chloramphenicol, thiamphenicol, florfenicol and its major metabolite florfenicol amine from poultry tissues and its results were compared with those of conventional shaking extraction, ultrasonic extraction, and pressurized liquid extraction. Decreasing the polarity of water by successively increasing the extraction temperature from 50°C to 200°C at the moderate pressure enabled selective, highly effective extractions to be performed. Rapid quantification of the target compounds was carried out by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). The critical parameters of subcritical water extraction such as solvent modifier, temperature, pressure, extraction time, and static cycles were varied with control. The optimized extraction procedures using subcritical water as extraction solvent, were carried out on a pressurized liquid extractor operated at 150°C and 100bar, applying two static cycles for 3min. Average recoveries of the four analytes from fortified samples ranged between 86.8% and 101.5%, with relative standard deviations (RSDs) lower than 7.7%. The limits of detection (LODs) and quantification (LOQs) for the target compounds were in the ranges of 0.03-0.5μgkg(-1) and 0.1-2.0μgkg(-1), respectively. The proposed method is fast, sensitive, water-based thus more environmental acceptable, making it a suitable replacement for conventional organic solvent extraction in veterinary drug residue analysis.

Determination of N-nitrosamines by automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometry

An automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometric procedure was developed for the determination of three N-nitrosamines (N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine) in water samples. Response surface methodology was employed to optimize relevant extraction parameters including extraction time, dispersive solvent volume, water sample pH, sodium chloride concentration, and agitation (stirring) speed. The optimal dispersive liquid-liquid microextraction conditions were 28 min of extraction time, 33 μL of methanol as dispersive solvent, 722 rotations per minute of agitation speed, 23% w/v sodium chloride concentration, and pH of 10.5. Under these conditions, good linearity for the analytes in the range from 0.1 to 100 μg/L with coefficients of determination (r(2) ) from 0.988 to 0.998 were obtained. The limits of detection based on a signal-to-noise ratio of 3 were between 5.7 and 124 ng/L with corresponding relative standard deviations from 3.4 to 5.9% (n = 4). The relative recoveries of N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine from spiked groundwater and tap water samples at concentrations of 2 μg/L of each analyte (mean ± standard deviation, n = 3) were (93.9 ± 8.7), (90.6 ± 10.7), and (103.7 ± 8.0)%, respectively. The method was applied to determine the N-nitrosamines in water samples of different complexities, such as tap water, and groundwater, before and after treatment, in a local water treatment plant.

Subcritical water extraction and antioxidant activity evaluation with on-line HPLC-ABTS(·+) assay of phenolic compounds from marigold (Tagetes erecta L.) flower residues

Subcritical water extraction (SWE) of phenolics was investigated from marigold (Tagetes erecta L.) flower residues. The total phenolics content (TPC), total flavonoids content (TFC) and antioxidant capacities of extracts were determined, furthermore, antioxidant activities of individual compounds were evaluated with on-line HPLC-ABTS(•+) system. The optimum SWE time was 45 min, solid-to-liquid ratio was 1:50, and the highest TPC and TFC were obtained at 220 °C respectively. The effect of SWE temperature on TPC and TFC was significant (p < 0.05), and TPC was ranged from 28.42 ± 0.94 to 124.27 ± 1.94 (mg GAE/g), and TFC ranged from 34.21 ± 0.36 to 133.22 ± 1.57 (mg GAE/g) between 80 and 220 °C. On-line HPLC-ABTS(•+) profiles revealed that quercetagetin from SWE at 200 °C had nearly twofold radical scavenging activities than that by leaching extraction.

Enrichment of vanillin in barley malt by hydrolysis in high temperature and high pressure steam

Malted barley was treated with saturated steam at temperatures ranging from 180 to 220 °C, that is, high temperature and high pressure steam (HHS), and a control sample exposed to saturated liquid water in the same temperature range. The malt treated in steam was extracted with water (70 °C) for 15 min after drying. Vanillin which gave beer preferable flavor was detected in all malt extracts, both after treatment with steam and in effluent from malt exposed to liquid water. Hydrolysis of ingredients in the malt occurred even in steam. The treatment of natural products in HHS could be a new thermal technique to provide a special ingredient for food industry, for example, malt for beer.

Two-stage pretreatment of rice straw using aqueous ammonia and dilute acid

Liberation of fermentable sugars from recalcitrant lignocellulosic biomass is one of the key challenges in production of cellulosic ethanol. Here we developed a two-stage pretreatment process using aqueous ammonia and dilute sulfuric acid in a percolation mode to improve production of fermentable sugars from rice straw. Aqueous NH₃ was used in the first stage which removed lignin selectively but left most of cellulose (97%) and hemicellulose (77%). Dilute acid was applied in the second stage which removed most of hemicellulose, partially disrupted the crystalline structure of cellulose, and thus enhanced enzymatic digestibility of cellulose in the solids remaining. Under the optimal pretreatment conditions, the enzymatic hydrolysis yields of the two-stage treated samples were 96.9% and 90.8% with enzyme loadings of 60 and 15FPU/g of glucan, respectively. The overall sugar conversions of cellulose and hemicellulose into glucose and xylose by enzymatic and acid hydrolysis reached 89.0% and 71.7%, respectively.

Characteristics of lignin from flax shives as affected by extraction conditions

Lignin, a polyphenolic molecule, is a major constituent of flax shives. This polyphenolic molecular structure renders lignin a potential source of a variety of commercially viable products such as fine chemicals. This work compares the performance of different lignin isolation methods. Lignin from flax shive was isolated using both conventional alkaline extraction method and a novel experimental pressurized low polarity water (PLPW) extraction process. The lignin yields and chemical composition of the lignin fractions were determined. The conventional alkali treatment with 1.25 M NaOH, heated at 80 °C for 5 h, extracted 92 g lignin per kg flax shives, while lignin yields from the PLPW extracts ranged from 27 to 241 g lignin per kg flax shives. The purity and monomeric composition of the lignins obtained from the different extraction conditions was assessed via UV spectroscopy and alkaline nitrobenzene oxidation. Lignin obtained from conventional alkali treatment with 1.25 M NaOH, heated at 80 °C for 5 h was of low purity and exhibited the lowest yields of nitrobenzene oxidation products. With respect to alkali assisted PLPW extractions, temperature created an opposing effect on lignin yield and nitrobenzene oxidation products. More lignin was extracted as temperature increased, yet the yield of nitrobenzene oxidation products decreased. The low yield of nitrobenzene oxidation products may be attributed to either the formation of condensed structures or the selective dissolution of condensed structures of lignin during the pressurized alkaline high temperature treatment. Analytical pyrolysis, using pyroprobe GC-MS, was used to investigate the molecular composition of the lignin samples. The total yield of pyrolysis lignin products was 13.3, 64.7, and 30.5% for the 1.25 M NaOH extracted lignin, alkaline assisted PLPW extracted lignin, and the unprocessed flax shives, respectively. Key lignin derived compounds such as guaiacol, 4-vinyl guaiacol, 4-methyl guaiacol, syringol, eugenol, isoeugenol, catechol, homocatechol, and vanillin were detected in all of the samples.

Extraction and separation of carbohydrates and phenolic compounds in flax shives with pH-controlled pressurized low polarity water

A bench-scale pressurized low polarity water (PLPW) extractor was used for the extraction and separation of hemicellulose, cellulose, lignin, and other phenolic compounds in flax shives. In the first part of this research, the key PLPW extraction process variables of temperature, pH, and flow rate, were optimized using central composite design (CCD). Temperature and pH of water had a significant affect on the fractionation of carbohydrates (cellulose and hemicellulose), lignin, and other phenolics. The optimal extraction conditions for the separation of hemicellulose and lignin, determined by the optimization using CCD, were 170 degrees C, pH 3.0, and a flow rate of 2.5 mL/min. Under these extraction conditions, 39.3% of the initial biomass or feed, 70.1% of the hemicellulose, 35.3% of the lignin, and 5.3% of the cellulose were extracted from the flax shives. In order to improve the purity and yield of the cellulose, a two-stage PLPW extraction was examined. The first stage was designed to remove hemicellulose by water at 170 degrees C and the second stage was intended for delignification by a pH 12 buffer at 220 degrees C. The two-stage PLPW extraction effectively removed 63.2% of the feed, 97.3% of hemicellulose, and 86.3% of lignin, while solubilizing 23.9% of cellulose; resulting in a solid residue containing 0.7 g of hemicellulose, 3.5 g of lignin, and 27.3 g of cellulose/100 g of DFS. The PLPW extraction is able to extract and separate components in flax shives by changing pH and temperature. The best case occurs between pH 9.5 and 12, resulting in maximum solubilization of hemicellulose and lignin.

Optimization of the extraction of anthocyanin from Bokbunja (Rubus coreanus Miq.) marc produced during traditional wine processing and characterization of the extracts

The extraction of anthocyanin from Bokbunja (Rubus coreanus Miq.) marc generated during traditional wine processing was optimized using response surface methodology (RSM). A face-centered cube design (FCD) consisting of 17 experimental runs, including five replicates at the center point, was used to investigate the effects of the three variables (solid-liquid ratio, time, and temperature) on anthocyanin extraction, and the results showed that the relationship between the three variables and the total anthocyanin content followed a quadratic model (R2=0.8853). In addition, the RSM analysis predicted that the optimum conditions for extraction consisted of a solid-liquid ratio of 20, a time of 60min, and a temperature of 60 degrees C. Verification tests performed under these optimum conditions gave 34.7+/-1.4mg/100g of anthocyanin, which was close to predicted value of 37.2mg/100g. Additionally, analysis of water extracts prepared using the predicted optimum conditions revealed that the carbohydrates (sugar and pectin) in Bokbunja marc underwent significant variation toward the formation of by-products (glycerol and uronic acids) during yeast fermentation, and that the amount of anthocyanin produced was reduced 10-fold when compared to the original extraction. Further, the results of HPLC-PDA-MS/MS analysis of the anthocyanins extracted from Bokbunja marc revealed the presence of six anthocyanin components, which were tentatively identified as cyanidin 3-O-sambubioside, cyanidin 3-O-xylosylrutinoside, cyanidin 3-O-rutinoside, pelargonidin 3-O-rutinoside, delphinidin 3-O-rutinoside-?, and delphinidin 3-O-glucuronide.

Fractionation of flax shives by water and aqueous ammonia treatment in a pressurized low-polarity water extractor

Fractionation of flax shives into cellulose, hemicellulose, and lignin with a two-stage extraction process using water and aqueous ammonia was carried out in a pressurized low-polarity water extractor operated at different temperatures, flow rates, and ammonia concentrations. During the first stage with water, 84% of hemicellulose and 32% of lignin were removed at 190 degrees C at a flow rate of 1.5 mL/min for 30 min. During the second stage with aqueous ammonia, more than 77% of the lignin was removed, and hemicellulose removal reached 95% at 200 degrees C at a flow rate of 0.5 mL/min and with a solvent/feed ratio of 40 mL/g. The temperature and flow rate had a significant effect on lignin removal. The impact of additives (anthraquinone and hydrogen peroxide) and modifications (overnight soaking, reduced particle size, and elevated temperature) on lignin extraction was also studied. The combination of higher temperatures and reduced particle sizes resulted in enhanced lignin extraction. The extraction profiles of free phenolics (vanillin, acetovanillone, and vanillic acid) during the two-stage processing were monitored and compared with those of lignin.