Subcritical water extraction of phenolic compounds from flaxseed meal sticks using accelerated solvent extractor (ASE)

Subcritical water extraction (SWE) is a technique based on the use of water as an extractant, at temperatures between 100 and 374 °C and at a pressure high enough to maintain the liquid state. SWE provides higher selectivities, low cost, and shorter extraction times. In this study, phenolic compounds in flaxseed (Linum usitatissimum L.) meal sticks were extracted with subcritical water using accelerated solvent extractor. For this aim, the interactions between temperature (160, 170, and 180 °C) and extraction time (5, 15, 30, and 60 min) for subcritical water extraction of SDG lignan, total phenolics, and total flavonoids from flaxseed meal sticks were investigated. The highest extraction yield of SDG lignan (77.01 %) in subcritical water extracts was determined at 160 °C for 60 min. However, high extraction yields were obtained as 70.67 and 72.57 % at 170 and 180 °C for 15 min, respectively. Also, the highest extraction yield of total phenolics (70.82 %) and total flavonoids (267.14 %) were determined at 180 °C for 15 min. Besides, high correlations between SDG lignan–total phenolics, SDG lignan–total flavonoids, and total phenolics–total flavonoids were obtained from 0.86 to 1 in water extracts.     

5-Hydroxymethylfurfural (HMF) formation during subcritical water extraction

The aim of this study was to investigate the effect of material type (artichoke leave, lemon peel, flaxseed meal), extraction temperature (50, 100, 120, 140, 160, 180, 200 °C) and static extraction time (5, 15, 30, 45 min) on 5-hydroxymethylfurfural (5-HMF) formation during subcritical water extraction. 5-HMF content of artichoke leave and lemon peel extracts increased 7.2 and 26.1 times with the rise of extraction temperature from 160 to 180 °C for 5 min during subcritical water extraction, respectively. Besides, 5-HMF content of artichoke leave, lemon peel and flaxseed meal extracts increased 1.4, 2.0 and 4.5 times as static extraction time increased from 15 to 45 min at 180 °C during subcritical water extraction, respectively. The highest 5-HMF content of artichoke leave and lemon peel extracts were obtained as 58.83 and 231.21 mg/L at 180 °C and 45 min, respectively. However, for flaxseed meal, the highest 5-HMF content (222.94 mg/L) was obtained at 200 °C and 15 min during subcritical water extraction.     

PROCESSING AND PROPERTIES OF EXTRUDED FLAXSEED-CORN PUFF

The effects of flaxseed meal (0, 5, 10 and 15%) in flaxseed meal/corn meal blend and processing variables, including moisture content (16, 18 and 20%), and screw speed (200, 300 and 400 rpm), on extrudate chemical property (lignan residue) and physical properties (specific volume, hardness and color) were studied. The lignan compounds in the flaxseed and corn meals were 2.27 and 0 mg/g, respectively, before extrusion. A higher flaxseed meal level and a higher screw speed favored the retention of lignan compounds, but higher feed moisture showed the opposite effect. About 25–52% lignan compounds were lost after extrusion. Increasing flaxseed meal level, increasing feed moisture or decreasing screw speed significantly reduced the expansion and resulted in harder extrudate that was darker, more reddish and less yellow.     

Validation of an Electrochemical Detection–High-Performance Liquid Chromatography Method for Simultaneous Determination of Lignans in Flaxseed (Linum usitatissimum L.)

Flaxseed is a major source of lignans, which are important bioactive compounds. The aims of this work were to validate a liquid chromatographic method for the rapid and simultaneous determination of the main lignans in flaxseed using high-performance liquid chromatography coupled with electrochemical detection and to analyze the composition of commercial samples of flaxseed. The performance criteria of the proposed method demonstrate that the method can be used for the analysis of secoisolariciresinol diglucoside (SDG), secoisolariciresinol (SECO), matairesinol (MATA), pinoresinol (PINO), lariciresinol (LARI), hydroxymatairesinol (HYDROXY), and isolariciresinol (ISOLARI) in flaxseeds at suitable levels. Calibration curves were determined for six different concentrations of standard solutions injected in triplicate. The sensitivity of the calibration curve was evaluated considering the confidence intervals of the intercept and slope. The limit of detection and limit of quantification were 7.4 and 10.9 μg/l, respectively, for LARI and 17.7 and 37.5 μg/l, respectively, for MATA. The relative standard deviation of repeatability values were lower than 2.59 %, which are acceptable because the Horwitz ratio values were 0.1 for all of the lignans. The recoveries of lignans were in the range of 74–100 % of SECO, which are consistent with the literature. The precision of the proposed method was determined by analyzing four flaxseed samples of different years and varieties. SDG was the main lignan present in all the samples, followed by ISOLARI and HYDROXY.     

Optimizing the Supercritical Fluid Extraction of Lutein from Corn Gluten Meal

Supercritical CO₂ was used to extract xanthophylls from corn gluten meal (CGM). Data from a Box-Behnken experimental design was used to model optimal lutein extraction based on extraction temperature (40–80 °C), pressure (5500–7500 psi), and fraction of ethanol co-solvent added (5–15% by volume of total solvent). Lutein extraction was also strongly correlated with zeaxanthin extraction with a correlation coefficient (r) of 0.995. The response surface model for lutein extraction indicated that the amount of co-solvent had the largest impact (p?<?0.001) on lutein extraction yield. Influence of temperature and pressure were limited to quadratic or interaction effects (p?<?0.15). The optimal lutein extraction conditions predicted with the model were a temperature of 40 °C, pressure of 6820 psi, and co-solvent (ethanol) addition of 15% by volume. At these conditions, lutein recovery from CGM was 2.6 times higher than the amount recovered with a quintuple extraction using ethanol and chloroform/dichloromethane (2:1). The strong linear effect of co-solvent addition suggests the possibility of further increasing lutein extraction with the addition of more co-solvent. CGM protein loss during extraction was also calculated and determined to be negligible.     

Demucilaging and dehulling flaxseed with a wet process

A continuous wet process for demucilaging and dehulling of flaxseeds was proposed to recover mucilage fraction and hull fraction from flaxseed. Mucilage was obtained by aqueous extraction and demucilaged flaxseeds were milled and fractionated by water separation in mixing tanks. Hull-rich, kernel-rich and an inseparable fraction were obtained with yields of 52.6, 22.3 and 12.7 g/100 g, respectively, when disk gap was set as 0.4 mm. The hull content of kernel-rich fraction and kernel content of hull-rich fraction were determined as 20.9 and 11.1 g/100 g, respectively. Although 11.5% oil, 15.3% protein and 9.6% secoisolariciresinol diglucoside (SDG) were lost during the demucilaging and dehulling of flaxseed, SDG was enriched in the hull-rich fraction and the inseparable fraction, while flaxseed oil in the kernel-rich fraction. Compared with dry processes, the proposed wet process is time-consuming and requires substantial amount of water. However, it is continuous and easy to scale up, and can be economical when an aqueous extraction of oil is used. It is also a good alternative for recovery of flaxseed gum and enrichment of SDG.     

Screening the Experimental Domain for the Microwave-Assisted Extraction of Secoisolariciresinol Diglucoside from Flaxseed Prior to Optimization Procedures

This paper presents the first part of a study that aims at developing an optimized microwave-assisted method for extracting the lignan secoisolariciresinol diglucoside from defatted flaxseed meal. Two-level fractional factorial designs were used for screening the following factors: the microwave power level (30–360 W), the time of residence in the microwave cavity (1–25 min), the concentration of NaOH (0.25–1 M), and the mode of microwave power application (power on 30 and 60 s/min). The experimental domain had to be adjusted after each screening in order to focus the future optimization study within the factors' ranges likely to contain the optimal extraction conditions.     

微生物发酵法提取亚麻木脂素

亚麻木脂素(SDG)是一种植物雌激素,具有多种生理功能。按2.5%的接种量将米曲霉Asp.oryzae 39#接种于亚麻籽粉,25～30℃发酵120h,再经丙酮提取,亚麻木脂素粗提物得率为21%～22%,SDG得率为16‰～17‰。发酵法提取SDG的提取率比未经发酵提高了50%。     

Dietary flaxseed lignan or oil combined with tamoxifen treatment affects MCF‐7 tumor growth through estrogen receptor‐ and growth factor‐signaling pathways

This study aimed to elucidate which component of flaxseed, i.e. secoisolariciresinol diglucoside (SDG) lignan or flaxseed oil (FO), makes tamoxifen (TAM) more effective in reducing growth of established estrogen receptor positive breast tumors (MCF‐7) at low circulating estrogen levels, and potential mechanisms of action. In a 2×2 factorial design, ovariectomized athymic mice with established tumors were treated for 8 wk with TAM together with basal diet (control), or basal diet supplemented with SDG (1 g/kg diet), FO (38.5 g/kg diet), or combined SDG and FO. SDG and FO were at levels in 10% flaxseed diet. Palpable tumors were monitored and after animal sacrifice, analyzed for cell proliferation, apoptosis, ER‐mediated (ER‐α, ER‐β, trefoil factor 1, cyclin D1, progesterone receptor, AIBI), growth factor‐mediated (epidermal growth factor receptor, human epidermal growth factor receptor‐2, insulin‐like growth factor receptor‐1, phosphorylated mitogen activated protein kinase, PAKT, BCL2) signaling pathways and angiogenesis (vascular endothelial growth factor). All treatments reduced the growth of TAM‐treated tumors by reducing cell proliferation, expression of genes, and proteins involved in the ER‐ and growth factor‐mediated signaling pathways with FO having the greatest effect in increasing apoptosis compared with TAM treatment alone. SDG and FO reduced the growth of TAM‐treated tumors but FO was more effective. The mechanisms involve both the ER‐ and growth factor‐signaling pathways.     

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.     

Flaxseed Lignans: Source,Biosynthesis, Metabolism,Antioxidant Activity,Bio‐Active Components,and Health Benefits

ABSTRACT: Lignans are compounds found in a variety of plant materials including flaxseed, pumpkin seed, sesame seed, soybean, broccoli, and some berries. The major lignan in flaxseed is called secoisolariciresinol diglucoside (SDG). Once ingested, SDG is converted in the colon into active mammalian lignans, enterodiol, and entero‐lactone, which have shown promise in reducing growth of cancerous tumors, especially hormone‐sensitive ones such as those of the breast, endometrium, and prostate. Known for their hydrogen‐donating antioxidant activity as well as their ability to complex divalent transition metal cations, lignans are propitious to human health. The extraction methods vary from simple to complex depending on extraction, separation, fractionation, identification, and detection of the analytes. Flax lignan is also a source of useful biologically active components found in plant foods, such as phytochemicals, and it is considered a functional food. The safety issues in flaxseed are also briefly discussed.     

Secoisolariciresinol diglucoside determination in flaxseed (Linum usitatissimum L.) oil and application to a shelf life study

A high-performance liquid chromatographic (HPLC) reliable and sensitive method with diode array detection (DAD) system has been developed for the determination of secoisolariciresinol diglucoside (SDG) in flaxseed oil. An analytical methodology based on the sample extraction with methanol/water (80:20, v/v), subsequent purification of the sample and analysis of the extract by HPLC/DAD is proposed for the determination of SDG in flaxseed oil. The coefficient of determination of the standard calibration curve was 0.999, the limit of detection was 0.08 μg/mL, and the limit of quantification was 0.27 μg/mL. The recovery test was conducted adding four different concentrations of standard solution to the blank sample. The recovery ranged from 90% to 95%. To our knowledge, the presence and quantification of SDG in flaxseed oil has never been reported. The proposed method was tested to study the variation in SDG content in flaxseed oil during a shelf-life test to verify its applicability in quality control for oil industries. The dark and the low temperature of storing together allowed to preserve SDG. A slight pro-oxidant effect was observed for the addition of antioxidant to the flaxseed oil.     

Evaluation of a Microwave-Assisted Extraction Method for Lignan Quantification in Flaxseed Cultivars and Selected Oil Seeds

An optimized microwave-assisted extraction (MAE) method was evaluated through repeatability, recovery and efficiency testing. The repeatability tests, performed by three users over time, were not significantly different. The recovery of lignan throughout the extraction, preparation and analysis steps is 97.5% with a coefficient of variation <1%. The MAE method is efficient for extracting lignans from the plant matrix, and it achieves significantly higher extraction yields than the two established reference methods. The applicability of the MAE method was demonstrated by extracting lignans from a variety of plant samples. The secoisolariciresinol diglucoside (SDG) content of seven flaxseed cultivars grown in Saint-Mathieu-de-Beloeil, QC, in 2009 ranged from 14.6 to 18.9 mg SDG per gram of seed. Flax hulls produced in Winchester, ON, in 2010 were very rich in lignan; their SDG content was 40.0 mg/g of flax hull. Sesame seeds contained 0.18–1.89 mg SECO (aglycone of SDG) per gram of seed, with significant differences among black, white and brown sesame seed. Chia seeds contained 0.99–1.29 mg SECO per gram of seed, with significant differences among batches of seeds. Sunflower seeds had 0.046 mg SECO per gram of sample and almonds had 0.029 mg SDG per gram of sample. The optimized and evaluated MAE method is recommended for the general analytical quantification of lignans in plant samples.     

Microwave‐assisted extraction of secoisolariciresinol diglucoside from flaxseed hull

Microwave‐assisted extraction (MAE) of secoisolariciresinol diglucoside (SDG) from defatted flaxseed hull (DFH) was studied. The effects of pre‐soaking methods and extraction parameters (ethanol concentration (0–100%, v/v), microwave energy input (50–390 W), liquid to solid ratio (5:1 to 40:1, mL g^?1) and irradiation time (10–330 s)) on the SDG yield were investigated. Response surface methodology (RSM) was applied to optimise the MAE conditions as irradiation time 90.5 s, ethanol concentration 40.9% (v/v), liquid to solid ratio 21.9:1 (mL g^?1) and microwave power 130 W. The SDG recovery from DFH with MAE was 11.7 g SECO kg^?1 DFH (on dry‐weight basis), which was significantly higher than that of stirring extraction (10.0 g SECO kg^?1 DFH) and Soxhlet extraction (7.60 g SECO kg^?1 DFH). Compared with stirring extraction and Soxhlet extraction, MAE showed its superiority in improving SDG yield and saving time and energy. Copyright © 2007 Society of Chemical Industry     

Calibration of artificial neural network and partial least squares regression models for the prediction of secoisolariciresinol diglucoside contents in microwave-assisted extracts of various flaxseed (Linum usitatissimum L.) samples

Partial least squares (PLS) and artificial neural network (ANN) regression models were calibrated for predicting the content of secoisolariciresinol diglucoside (SDG) in six flaxseed cultivars, defatted flaxseed meal and flax hulls extracts. The SDG was quantified by HPLC after microwave-assisted extraction (MAE) from flaxseed; the data were used in conjunction with the light absorption of the extracts measured after Folin–Ciocalteu’s assay at 289, 298, 343 and 765 nm, in order to calibrate the predictive PLS and ANN models. The accuracy and the predictive ability of the models ranged from good to excellent as indicated by RPD values (the ratio of the standard deviation of the reference values to the standard error of prediction) of 5.03–13.7. The PLS and ANN predictive models are useful to the flaxseed processing industry for rapidly and accurately predicting the SDG contents of various flaxseed samples based on their UV–Vis light absorption.     

开环异落叶松树脂酚的提取及其对乳液稳定性的影响研究

以含50%开环异落叶松树脂酚二葡萄糖苷(SDG)的亚麻木酚素粗提物(50%SDG)为水解原料,对制备开环异落叶松树脂酚(SECO)粗提物的HCl浓度和水解时间进行优化,进一步通过溶剂萃取、真空冷冻干燥工艺制备SECO粗提物,并将其应用于磷脂-亚麻籽油乳液体系中,研究水解前后亚麻木酚素粗提物对磷脂-亚麻籽油乳液在65℃高温储藏过程中稳定性的影响。结果表明:在HCl浓度1 mol/L、水解时间120 min的条件下水解,可制备SECO含量为65%的SECO粗提物(65%SECO);在磷脂-亚麻籽油乳液高温储藏(65℃)过程中,65%SECO组乳液粒径无显著变化,但对照组和50%SDG组乳液粒径增大;与对照组乳液相比,储藏7 d,65%SECO和50%SDG可分别将乳液中氢过氧化物含量降低11%和27%。由此可见,在磷脂-亚麻籽油乳液的高温储藏(65℃)过程中,50%SDG具有较好的抑制油脂氧化的效果,但通过水解制备的65%SECO能显著提高磷脂-亚麻籽油乳液的物理稳定性。     

Stability of α-Linolenic Acid and Secoisolariciresinol Diglucoside in Flaxseed-Fortified Macaroni

Research was conducted to determine the stability of secoisolariciresinol diglucoside (SDG) and α‐linolenic acid (ALA) in flaxseed‐fortified macaroni. Macaroni was fortified with whole ground flaxseed (GWF) at levels of 10% to 20% and then dried under low temperature (LT, 40°C), high temperature (HT, 70°C), or ultrahigh temperature (UHT, 90°C). Macaroni was also fortified with 15% ground hull (GHF) or steam‐treated whole ground flaxseed (GSWF) and dried under UHT. The dried macaroni was stored for 32 wk under ambient conditions. Approximately 80% to 95% of the SDG was recovered, indicating that SDG was stable during the 32‐wk storage period. Total lipid and ALA levels in all flaxseed macaroni treatments remained unchanged throughout the 32‐wk storage. This observation was consistent across the drying conditions and flaxseed addition levels. Conjugated diene (CD) values indicated that macaroni fortified with GWF did not oxidize significantly during the 32‐wk storage for the macaroni dried under HT or UHT. However, a significant increase (P <0.05) in CD values for macaroni containing 10% and 20% flaxseed and dried using LT was observed at the 32‐wk storage period. Headspace volatile concentrations did increase over the storage period for macaroni containing GWF, but the increase was not significant. Significant increases (P < 0.05) in oxidation were found by 24 wk in GHF‐ and GSWF‐fortified macaroni. GWF macaroni dried at UHT, HT, or LT could be used as a way to improve our dietary consumption of ALA and SDG. However, use of steam as a method to inactivate unwanted enzyme activity is not recommended.     

Extraction of lignans, proteins and carbohydrates from flaxseed meal with pressurized low polarity water

This study examined the application of pressurized low polarity water (PLPW) extraction of lignans, proteins and carbohydrates from defatted flaxseed meal. Key processing conditions included temperature (130, 160, 190 °C), solvent pH (4, 6.5 and 9), solvent to solid ratio (90, 150 and 210 mL/g) and introduction of co-packing material (0 and 3 g glass beads). The addition of 3 g glass beads increased the yields for all target compounds. The maximum yield of lignans (21 mg/g meal) was obtained at 170 °C with solvent to solid ratio of 100 mL/g meal at pH 9. Optimal conditions for protein extraction were pH 9, solvent to solid ratio of 210 mL/g meal and 160 °C. Total carbohydrates recovery was maximized at 215 mg/g meal (50% recovery) at pH 4 and 150 °C with solvent to solid ratio of 210 mL/g meal. The increase of temperature accelerated extraction, thus reducing solvent volume and time to reach equilibrium. For the extraction of proteins and carbohydrates, however, a temperature of 130-160 °C is recommended, as proteins and carbohydrates are vulnerable to thermal degradation.     

Effects of germination on tocopherol,secoisolarlciresinol diglucoside,cyanogenic glycosides and antioxidant activities in flaxseed (Linum usitatissimum L.)

The changes in chemical composition and antioxidant activities of brown and golden flaxseeds (Linum usitatissimum L.) during 5-day germination were investigated. Flaxseeds germinated in a dark and closed incubator at the temperature of 25 °C. With noticeable reduction in fat content, germinated flaxseeds were determined higher percentage of linolenic acid. The total phenolic content and antioxidant activities increased with germination time. The highest amount of secoisolarlciresinol diglucoside (SDG) was found in 2-day germinated brown and golden flaxseeds, which increased 1.04-fold and 1.09-fold, respectively, and germinated flaxseed oil was found rich in SDG. Intriguingly, germination increased the α-tocopherol content from 0 to 4.58 mg per 100 g and 0 to 7.83 mg per 100 g in brown and golden flaxseeds while γ-tocopherol decreased. Germination process also reduced the total content of cyanogenic glucosides, the content of linustatin, neolinustatin and lotaustralin decreased significantly, but caused an increase in the content of linamarin. Therefore, germination can be utilised as an effective method to improve the nutritional value of flaxseed.     

Pressurized low polarity water extraction of lignans from whole flaxseed

The application of pressurized low polarity water (PLPW) extraction to the production of flaxseed lignans-rich products has been studied, and the key geometric and process conditions, including temperature, flow rate, and total volume have been determined and optimized. Maximum amounts of lignans and other flaxseed bioactive, including proteins were extracted at 160 °C and 5.2 MPa. However, on a dry weight basis the most concentrated extracts in terms of lignans and other phenolic compounds were obtained at 140 °C and 5.2 MPa. A flow rate of 0.5 mL/min was optimal for the extraction of lignans from flaxseed (Linum usitatissimum L.) and a total volume of 30–40 mL/g of seed was required to maximize the recovery. Higher flow rates increased the rate of the extraction but required larger water volumes. Bed depth to ID ratios of 5–18 resulted in faster extraction and maximum recovery (90–95%) at water to seed ratios of 30–50 mL/g. Larger depth to ID ratios (15–18) would allow the use of lower solvent to solid ratios (14–20 mL/g) and would still result in yields of 84–90%.