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.     

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。     

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.     

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.     

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     

Triticale bran and straw: Potential new sources of phenolic acids,proanthocyanidins, and lignans

The distribution of phenolic acids (free and bound), proanthocyanidins, and lignans in defatted triticale bran and straw was determined. For comparison, wheat, rye and oat brans as well as triticale flakes and leaves were also assayed. Most phenolic acids were present in the bound form (89–98%), and released under alkaline extraction conditions. The content of phenolic acids ranged from 65.2 to 252.5 mg/100 g in samples in which ferulic acid predominanted. Triticale straw was the richest source of proanthocyanidins, containing 862.5 mg/100 g (catechin equivalents) of tissue. Triticale straw contained 0.27 mg/100 g of lignan secoisolariciresinol diglucoside (SDG), whereas the bran had only 0.01 mg/100 g. The oxygen radical absorbance capacity (ORAC, μM Trolox equivalents/g defatted material) showed that antioxidant activity of bound phenolics was higher than those of free phenolics. This is the first report on phenolic acids, proanthocyanidin, and lignans content of Canadian triticale by-products, indicating that they may have the potential for use as nutraceuticals and/or functional food ingredients.     

Optimization of Microwave-Assisted Extraction of Phenolic Antioxidants from Grape Seeds (Vitis vinifera)

Grape seeds (Vitis vinifera) are rich in phytochemicals that have antioxidant properties. The influence of independent variables such as microwave power (100, 150, and 200 W), extraction time (2, 4, and 6 min), and solvent concentration (30%, 45%, and 60% ethanol) and their interactions on total phenols and the antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP)) were determined; and the microwave-assisted extraction (MAE) process was optimized using a central composite design. The total phenols that were expressed as gallic acid equivalents (GAE), catechin equivalents (CAT), and tannic acid equivalents (TAE) were significantly influenced by the solvent concentration and the time of extraction. A numerical optimization was carried out to obtain the overall conditions for MAE of phenolic antioxidants from grape seed. The response variables were maximized for 6 min of MAE of grape seed (GS) with 32.6% ethanol at 121 W with a desirability function of 0.947. The predicted extraction yields were 13?±?0.89, 21.6?±?1.59, and 15.9?±?1.32 mg GAE, CAT, and TAE, respectively per gram of GS. The predicted antioxidant activity per gram of dry weight GS was 80.9% for the inhibition of DPPH and 135 μM ascorbic acid equivalents for FRAP test. The predicted response values were significantly correlated with the observed ones as follows: GAE r?=?0.995, CAT r?=?0.990, TAE r?=?0.996, DPPH r?=?0.996, and FRAP r?=?0.996.     

Physical and cooking characteristics of black gram (Phaseolus mungoo L.) cultivars grown in India

Pulses are important component of diet, and information on their physical properties is needed for designing machines while cooking quality is important for consumer acceptance. Three black gram cultivars grown in India were evaluated for physical and cooking properties. Proximate composition revealed that three cultivars contained 24.5–26.7% protein, 1.1–1.3% fat, 2.8–3.7% ash and 60.4–63.3% carbohydrates. Length, breadth and thickness of seeds were in the range of 4.66–5.11 mm, 3.71–3.79 mm and 3.20–3.29 mm, respectively. True density and porosity varied from 1.25–1.29 g mL^?1 to 33.43–36.09%, respectively. Hydration and swelling capacities of the seeds varied from 0.036–0.041 g per seed to 0.037–0.042 mL per seed, respectively. Cooking time of unsoaked seeds varied significantly from 35.3 to 42.7 min. Hardness and adhesiveness of the cooked seeds varied from 2.12–2.55 kg to 0.02–0.99 kg s, respectively. The black gram cultivars are rich in protein, and soaking treatment improved their cooking quality.     

溶剂法提取亚麻籽木脂素(SDG)工艺优化研究

研究了溶剂法提取亚麻籽中木脂素的工艺,确定了单因素试验的最佳溶剂系统为70%的乙醇,提取温度为室温,时间为24 h。以木脂素得率为指标,采用二次正交旋转回归试验对溶剂法提取亚麻籽木脂素提取工艺进行优化,求得了二次正交旋转回归方程,确定了影响溶剂法木脂素得率的各因素的主次顺序依次为:提取时间、提取温度、乙醇浓度。用统计寻优方法进行方案寻优,可得乙醇浓度为70%、提取时间为28 h、提取温度为40℃时,木脂素得率最高为9.25%。     

Content,composition, and stereochemical characterisation of lignans in berries and seeds

In seed extracts of five oilseed species, in bran extracts of three cereal species, and in seed and/or whole berry extracts of 10 berry species, the concentrations of a large number of lignans and the enantiomeric composition of selected lignans were determined. In the case of sesame and hemp seeds, the lignan content and composition of the whole seeds was compared to that of the hulled seeds. The results showed that cloudberry seeds are the third most lignan-rich food source after linseeds and whole sesame seeds, and that most of the berry species analysed were more lignan-rich than the cereal brans. The lignans are concentrated in the hull of the oilseeds and in the seeds of the berries. In most samples, secoisolarici-, pino-, medio-, and syringaresinol were present as a mixture of two enantiomers.     

Cellulase-assisted release of secoisolariciresinol from extracts of flax (Linum usitatissimum) hulls and whole seeds

Extraction of secoisolariciresinol from seed hulls and whole seeds of flax was improved using an enzymatic step with cellulase R10 from Trichoderma reesei that allowed better yield as compared to β-glucosidase. The cellulase assisted extraction process was further optimised for different parameters such as duration and concentration of hydromethanolic extraction, duration of alkaline hydrolysis, pH, duration and incubation temperature as well as enzyme concentration. Best results were obtained using a method including the following successive steps: 16 h of 70% hydromethanolic extraction, 6 h of 0.1 M sodium hydroxide hydrolysis followed by a 6 h incubation with 1 unit ml⁻¹ of cellulase R10 in 0.1 M citrate–phosphate buffer pH 2.8 at 40 °C. Under these conditions, all forms of the main flax lignan were recovered as the aglycone form, i.e. secoisolariciresinol. Highest yields in secoisolariciresinol diglucoside (SDG) equivalent reached 7.72% of flaxseed hull (cv. Baladin) dry weight and 2.88% of whole seed (cv. Barbara) weight, thus allowing a significant improvement in comparison with published methods.     

Effect of refining on the lignan content and oxidative stability of oil pressed from roasted sesame seed

Oxidative stability of pressed and refined sesame oils during seven consecutive months of storage at room temperature was studied comparatively. Lignans, peroxide value (PV), p‐anisidine value (AV) and total oxidation value (TOTOX) were determined as evaluation indices. PV, AV and TOTOX of sunflower, corn and peanut oils were simultaneously monitored to compare their oxidative storage stabilities with the sesame oils. The total amount of lignans in the pressed and refined sesame oils were 1103 and 790 mg per 100 g respectively. The contents of sesamin and sesemolin in the pressed sesame oil were 734 and 369 mg per 100 g respectively. Sesamin and sesamolin content were reduced by 256 and 159 mg per 100 g, respectively, after refining. Nearly 40% of the sesamin epimerised to asarinin after oil refining. The results indicate that sesame oils pressed from roasted seed have far superior storage stability to oxidation than the other vegetable oils. This difference may be due to much higher sesamin and sesamolin contents in the pressed sesame oils. The results suggest lignan compositions and levels could be used as key indicators for evaluating the oxidative storage stability of sesame oil products as well as to differentiate between pressed and refined sesame oils.     

The effective parameters for subcritical water extraction of SDG lignan from flaxseed (Linum usitatissimum L.) using accelerated solvent extractor

The aim of this study was to investigate the effective parameters for subcritical water extraction of secoisolariciresinol diglucoside (SDG) lignan from flaxseed using accelerated solvent extractor. For this aim, the influence of extraction parameters such as material shape (flaxseed, ground flaxseed meal and flaxseed meal sticks), temperature (120, 140, 160 and 180 °C), extraction time (15, 30, 60 and 90 min), pressure (1.500 and 2.000 psi), fresh water (5, 40 and 100 %) and sample amount (5 and 10 g) was studied. SDG lignan analysis has been carried out by LC–MS/MS. It was shown that material shape, temperature, extraction time and sample amount had significant effect on SDG lignan content in water extracts (p < 0.05). The highest amount (12.94 mg/g) and extraction yield (72.57 %) were obtained at 180 °C for 15 min, 1.500 psi and 40 % fresh water using 5 g of flaxseed meal sticks.     

Comparison of Antimutagenic Activity of Phenolic Compounds in Newly Harvested and Stored Common Beans Phaseolus vulgaris against Aflatoxin B1

ABSTRACT: Phenolic compounds were extracted from recently harvested or stored black Jamapa beans ( Phaseolus vulgaris ) that were subjected or not to thermal treatment. The beans studied were cropped in the same area and were from the same lot. The highest amount of condensed tannins (CT) was found in the seed coat of recently harvested beans [222.41 ± 16mg of (+)-catechin equivalents per gram of seed coat]. After 2 yof storage, the amount of CT dropped significantly [35.8 ± 3.4 mg of (+) -catechin equivalents per gram of seed coat]. Thermal treatment significantly reduced the amount of CT in whole beans by approximately 70%. The raw seeds contained 13.76 ±1.2 mg of (+)-cat-echin equivalents per gram of seeds and a portion of CT appeared in the broth [9.4 ± 0.1 mg of (+) -catechin equivalents per gram of lyophilized broth]. The antimutagenic activity of these extracted phenolic compounds was tested against aflatoxin B₁ (AFB₁) in the Kado microsuspension assay. Newly harvested beans showed higher antimutagenic activity against AFB₁ mutagenicity than stored beans. The results suggest that to take the maximum advantage of components with biological activity present in beans, they must be used fresh.     

Optimization of microwave-assisted extraction of triterpene saponins from defatted residue of yellow horn (Xanthoceras sorbifolia Bunge.) kernel and evaluation of its antioxidant activity

Microwave-assisted extraction (MAE) of triterpene saponins from defatted residue of yellow horn (Xanthoceras sorbifolia Bunge.) kernel was optimized in this study. Compared with the conventional extraction methods ultrasonic-assisted extraction (UAE) and heat reflux extraction (HRE), MAE possessed higher efficiency for the extraction of triterpene saponins. The MAE conditions including extraction temperature, extraction duration, irradiation power, ethanol concentration, ratio of solvent to material and extraction cycles were studied and optimized. The optimum extraction parameters were as follows: 51 °C, 7 min, 900 W, 32 ml/g, 42% (v/v) ethanol and 3 cycles. Under the above conditions, the highest extraction yield of triterpene saponins reached 11.62 ± 0.37% of defatted kernel, which was much higher than those of conventional extraction methods. In addition, MAE extract of triterpene saponins exhibited substantial free radical-scavenging activity with an IC₅₀ value of 0.782 mg/ml.

Industrial relevance

Large amounts of defatted kernels of yellow horn are discarded after oil extraction in biodiesel production. It is not only an environmental pollution but also a waste of bioresource. In fact, the residue still has potential for bioactive and medicinal use. Therefore, this study focused on the utilization of defatted kernels of yellow horn by optimizing MAE and evaluation of the antioxidant activity of the resulting extract. MAE provided a better way to deal with defatted kernels of yellow horn as a utilization of waste material of the bioactive resource in food and pharmaceutical industry.     

微波辅助提取薏苡仁油的研究

本文研究了微波辅助技术在薏苡仁油脂中的应用.通过对溶剂、微波功率、微波作用时间以及液固比对微波辅助提取薏苡仁油的影响进行单因素实验,确定了最佳的提取条件.实验结果表明,最佳的提取工艺为：100%的乙醇,微波功率为600W,微波处理时间为5～8min,液/固比为10.本文还比较了微波辅助提取技术、室温浸提、热回流提取技术,结果证明微波辅助提取技术无论提取效果还是提取效率均比传统工艺适合薏苡仁油的提取.     

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%.     

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.     

Changes in the parboiled seeds of Treculia africana caused by improper drying and microbial infection

Improper drying of the seeds of Treculia africana can lead to contamination by moulds and bacteria.Investigation revealed that moulds increased from 5·2 × 10⁴ per gram to 3·6 × 10⁷ per gram and bacteria increased from 3·5 × 10⁶ per gram to 76·1 × 10⁶ per gram when parboiled seeds were not dried for 7 days due to humid weather.The yield of white seed cotyledons decreased to 60·1% from 80·2% due to infection. The resultant white seed cotyledons contained only 4·47% oil compared with 7·07% in the normally dried parboiled seeds (control).The infection brought about an increase in the levels of sugars, amino acids and polyphenols in the parboiled seeds.     

Variation of sesamin,sesamolin and tocopherols in sesame (Sesamum indicum L.) seeds and oil products in Thailand

Sesame (Sesamum indicum L.) seed and oil contain abundant lignans, including sesamin, sesamolin and lignan glycosides. The aim of the present study was to determine sesamin, sesamolin and tocopherol contents in sesame seed and oil available in Thailand. The results showed that there was a large variation of sesamin and sesamolin contents in products. The distribution plot of sesamin and sesamolin contents in seeds showed that the mean values of sesamin and sesamolin were 1.55 mg/g (SD = 1.63; range n.d.–7.23 mg/g) and 0.62 mg/g (SD = 0.48; range n.d.–2.25 mg/g), respectively. The range of total tocopherols of these sesame lines was 50.9–211 μg/g seed. In commercial sesame oils, the ranges of sesamin and sesamolin were 0.93–2.89 mg/g oil and 0.30–0.74 mg/g oil, respectively, and tocopherol contents were 304–647 μg/g oil. The study reveals the extensive variability in sesamin, sesamolin and tocopherol contents among sesame products.