CN101570556B - Method for extracting secoisolariciresinol diglucoside from flax seeds or husks, extract obtained and use thereof - Google Patents

Abstract

The invention relates to a method for extracting secoisolariciresinol diglucoside from degummed flax seeds or husks, an extract containing the secoisolariciresinol diglucoside and use thereof. The method comprises crushing the degummed flax seeds or husks, degreasing, ultrasonic-microwave synergistic extracting, separating, depressurizing and concentrating, and drying to obtain the extract containing the secoisolariciresinol diglucoside. The method has high extraction rate for secoisolariciresinol diglucoside and high economical efficiency, and the extract is widely applied to bakery products,beverages, snack foods and the like and has great market potential.

Description

Method for extracting flax lignans from flax seeds or hulls, the obtained extract and its use

【Technical field】

The invention relates to the field of food science and the technical field of oil crop processing. More specifically, the present invention relates to a method for extracting flax lignans from degummed flaxseed or the shell-rich part of degummed flaxseed, and to an extract containing flax lignans and uses thereof.

【Background technique】

Flax (Linum usitatissimum L), also known as flax, belongs to the family Linaceae and is one of the oldest crops. Flaxseed is the seed in the flax fruit, each fruit contains 6-10 seeds. The shell of flaxseed is hard, with a shell rate of 42%-50% and a kernel rate of 50%-58%. In recent decades, the bioactive components in flaxseed have been gradually discovered and recognized by researchers, and the food industry has shown increasing interest in the development and utilization of flaxseed. The first is linseed oil rich in linolenic acid, which is of great help in the prevention and treatment of cardiovascular diseases. The second is the rich dietary fiber in flaxseed, the most important part of which is the soluble dietary fiber - flaxseed gum, which is a natural heteropolysaccharide with high viscosity, strong water holding capacity, excellent emulsification and foaming properties And stability, can reduce blood lipids, and has the effect of weight loss, beauty and nutrition. For more than a decade, the phytoestrogens rich in flaxseed, especially secoisolaricoresinol diglucoside (SDG), have attracted the attention of researchers. The content of SDG in flaxseed is much higher than that in other crops, and it is also the most important lignan in flaxseed. It can relieve menopausal symptoms, inhibit human breast cancer, prostate cancer, rectal cancer, and assist in the treatment of lupus nephritis and diabetes. play a beneficial role. In addition, flax lignans are also a good natural antioxidant. Due to the rich variety of bioactive ingredients in flaxseed, the National Cancer Institute (NCI) of the United States has listed flaxseed as one of the six anti-cancer plant research objects, and its development and utilization has become a key point for the development of functional foods and food ingredients. hotspot.

However, due to the lack of scientific understanding and processing methods, the development and utilization of flaxseed in my country has been at a relatively primitive level for a long time. So far, linseed has been mostly used as raw material for oil extraction, and the cake after oil extraction is often used as feed, and the utilization rate is low. How to make full use of the three main bioactive substances in flaxseed-linseed oil, flaxseed gum and flax lignans has become a hot spot in the comprehensive utilization of flax resources.

From the late 1990s to the early 2000s, the Crop Utilization Department of the Saskatoon Research Center in Canada, the University of Saskatchewan, the University of Toronto, the North Dakota State University in the United States, the Swedish University of Agricultural Sciences and the University of Helsinki in Finland were involved in flaxseed processing. Extensive research has been carried out on the development of flax lignans and flax lignans, especially the research on the biological activity of flax lignans, which has laid a foundation for its development, utilization and dietary supplementation.

In the extraction of flax lignans, Bakke and Klosterman first proposed a method of extracting SDG using 95% ethanol and 1,4-dioxane (1:1, v/v) as solvents when they discovered SDG. (Bakke J E and Klosterman H J.A new diglucoside fromflaxseed. Proceedings of the North Dakota Academy of Science, 1956(10): 18-22). Thereafter, Muir and Westcott proposed to use a fatty alcohol solution (methanol or ethanol) to extract lignan precursors from flaxseed defatted meal, then use alkaline hydrolysis to release lignans, and then separate and purify to obtain pure SDG (MuirAD and Westcott N D. Process for extracting and purifying lignans and cinnamic acid derivatives from flaxseed. CA 2216979.1996-10-03). Subsequently, Westcott and Paton used a similar method to extract the complex of SDG, HMGA and cinnamic acid glucoside from flaxseed (Westcott N D and Paton D. Complex containing lignan, phenolic and aliphatic substances from flax and process for preparing. US 6,264,853.2001 -07-24). Dobbins and Wiley used acetone aqueous solution to extract SDG, and then used alkaline hydrolysis to release SDG to obtain flax lignans (Dobbins T A and Wiley D B.A process for recovering secoisolariciresinoldiglycoside from de-fatted flaxseed. WO030849742003-10-16). Heintzman and Bennett (Heintzman R and Bennett M L.Process for extraction and stabilization of phytoestrogens from flaxseed and product therefrom.US 20030060420.2003-03-27), Pihlava et al. and purifying secoisolariciresinol diglcoside from flaxseed. US2004030108.2004-02-12) all use ethanol solution to extract SDG from defatted flaxseed powder. Shukla et al. (Shukla R, Hilaly A K and Moore K M. Process for obtaining lignan. US 6,767,5652004-07-27) also proposed to prepare SDG by solvent extraction. Abe et al. (Abe K, Iino T, Fujii W, et al. Process for producing SDG and foods and drinks containing the same. US20051584352005-07-21) used alkaline ethanol solution to extract SDG. Domestically, the extraction and purification of SDGs has just started. Wu Meijuan et al. (Wu Meijuan, Li Yulin, Tang Luoxiang, etc. The method of extracting, separating and purifying SDG from flax cake. CN1162438.2003-02-05) studied the method of extracting, separating and purifying SDG from flax cake, and proposed a method that is different from that of Muir and Westcott The method used is similar to the SDG extraction route. Wang Hao et al. (Wang Hao, Xiong Fei, Wu Jiajun, etc. Preparation method and application of flaxseed lignan total glycoside extract. CN1749262.2006-03-22) also used lower alcohol solution to extract SDG was extracted from, and Liu Dachuan et al. (Liu Dachuan, Pang Meixia, Wu Bo. Research on the Extraction Technology of Flaxseed Lignans - Secoisolaricine Resinol Diglucoside. China Oils and Oils, 2002, 27(5): 83-86) optimized the solvent extraction process of SDG. On the basis of organic solvent extraction and alkali hydrolysis, the inventor of the present invention also adopted a modified gel column to separate the extracted product, and obtained high-purity secoisolaricoresinol diglucoside (Xu Shiying, Wang Zhang, Zhang Wenbin, Zhang Xiaoming, Zhong Fang. A method for extracting and purifying secoisolaricoresinol diglucoside from flaxseed. CN200610038634).

The above studies all used the method of extracting SDG with organic solvents (lower alcohols or acetone). Although the stirring extraction method is low in cost, it takes a long time, consumes a large amount of solvent, and has low extraction efficiency. Therefore, researchers are constantly trying some emerging technologies to extract SDGs. Cacace et al. (Cacace J E and MazzaG. Pressurized low polarity water extraction of lignans from whole flaxseed. Journal of Food Engineering, 2006, 77: 1087-1095) tried to use subcritical water to extract SDG from defatted flaxseed powder. The extraction method avoids the use of organic solvents, and the yield is satisfactory, but the method requires high equipment investment and operating conditions, and is not suitable for industrial application. The inventor of the present invention once used microwave-assisted extraction of flax lignans (Zhang Wenbin, Xu Shiying. Microwave-assisted extraction process research of flax lignans. Natural product research and development. 2006, 18: 286-290), and achieved better than conventional The result of the extraction, but the solvent consumption is large, and the extraction efficiency still needs to be improved. Subsequent studies have shown that mixing the material with the extraction solvent to a thick state, and then performing ultrasonic and microwave synergistic extraction can obtain more ideal results.

In addition, considering the distribution of each component in linseed and the characteristics of linseed structure, the inventor proposes a process route for comprehensive utilization of linseed, especially linseed hulls, that is: adopting an appropriate process to combine linseed gum, linseed Oil, linseed protein and linseed hulls are partially separated or enriched, and then recycled respectively (Comprehensive Development and Utilization of Linseed Hulls, Jianzi [Jiao SW2008] No. 082). After wet debonding of linseed, linseed slime is obtained, which can be used to prepare linseed gum. The debonded linseed can be separated from the shell by wet method, and the obtained kernel-rich part can be used as a raw material for extracting linseed oil by aqueous enzymatic method, and the shell-rich part can be used as a raw material for extracting linseed lignans. This method of comprehensive utilization of flaxseed takes into account the three main bioactive components of flaxseed, which has important reference value for the comprehensive utilization of flaxseed.

【Content of invention】

[Technical problem to be solved]

The object of the present invention is to provide a method for extracting flax lignans from flax seeds or hulls.

Another object of the present invention is to provide an extract containing flax lignans.

Another object of the present invention is to provide the use of the extract containing flax lignans.

[Technical solutions]

The purpose of the present invention is to provide a method for extracting flax lignans synergistically with ultrasonic and microwave, so as to provide an effective way for the comprehensive development and utilization of flaxseed resources. The present invention uses degummed flaxseed or the shell-rich part of degummed flaxseed as raw material, and uses ethanol solution to quickly extract the lignans in the flaxseed shell under the condition of ultrasonic and microwave cooperative extraction, and obtains after concentration and spray drying Powder product with high lignan content (see accompanying drawing 1). The invention has high extraction rate of lignans and good process economy, and the product can be widely used in bakery products, beverages and leisure foods, etc., and has great market potential.

The present invention is achieved through the following technical solutions.

The invention relates to a method for extracting flax lignans from flax seeds or hulls. The method comprises the steps of:

(1) The degummed flaxseed is crushed and sieved with a 60-mesh sieve to obtain degummed flaxseed powder.

In the present invention, the degummed linseed should be understood as adopting the usual wet degumming method, the linseed is soaked for 60min at a temperature of 70°C, pH 6.0, and a material-to-water ratio of 1:7 (g/mL), and repeated several times The second degumming is to remove the gum existing on the surface of the flaxseed. Generally speaking, the residual gum content of the degummed linseed should be controlled at 1-2% (accounting for the total mass of linseed), which is beneficial to the next step of separation of kernel and shell and development and utilization of kernel-rich part and shell-rich part.

The pulverizing equipment used in this step is a variety of traditional Chinese medicine pulverizers sold in large quantities on the market. For example, the product sold by Zhejiang Wenling Machinery Factory under the trade name "Chinese Herbal Medicine Pulverizer", and the product sold by Zhengzhou Changxing Machinery Factory under the trade name "Ultrafine Powder Machine" Products sold by Shengzhou New Century Grinding Equipment Co., Ltd. under the trade name "Ultrafine Aquatic Feed Grinder" or Fujian Fengli Machinery Technology Co., Ltd. under the trade name "Superfine Grinder for Heat Sensitive Materials".

(2) The degummed linseed powder obtained in step (1) is mixed with n-hexane according to the ratio of 1 part by weight and 10-20 parts by weight, and then degreased with n-hexane for 1-3h under stirring in a closed container at normal temperature, and then carry out After centrifugal separation, the obtained residue is washed with n-hexane, and then subjected to centrifugal separation. The residue is degreased and degummed linseed powder, and then processed under reduced pressure to remove residual n-hexane.

In the present invention, the airtight container is a stainless steel reaction pot. For example, Wuxi Xishan Xuelang Chemical Equipment Factory sells products under the trade name "Stainless Steel Reactor", Wuxi Qingquan Chemical Equipment Factory sells products under the trade name "Stainless Steel Reactor", and Wuxi Zhenghai Petrochemical Equipment Co., Ltd. sells products under the trade name "Stainless Steel Reactor". Products sold by Electric Heating Reactor" or products sold by Shanghai Farfly Energy Technology Co., Ltd. under the trade name "Stirred Reactor".

Described centrifugation uses the centrifuge that the rotating speed that sells on the market is more than 2500r/m at present, for example Xiangyi Centrifuge Instrument Co., Ltd., Jiangsu Province Jintan City Medical Instrument Factory, Tianmei Technology Co., Ltd. and Shanghai Anting Scientific Instrument The products sold by the factory under the trade name "desktop high-speed centrifuge".

Usually, the residual fat content of the degreased and degummed linseed meal should be controlled at 1-2%, which is beneficial to the next step of separation of kernel and shell and development and utilization of kernel-rich part and shell-rich part.

The treatment under reduced pressure refers to such a treatment that n-hexane itself is removed by volatilization under a pressure of 1-5kPa.

(3) Add 30-60% (v/v) concentration of ethanol aqueous solution to the degreased and degummed linseed powder obtained in step (2) according to the ratio of 4-8 parts by weight per part, and mix uniformly; 50-300W/g, the total microwave input power is 150-600W/g, and the microwave power is 50-1000W/s for ultrasonic and microwave collaborative extraction.

In the present invention, the ultrasonic and microwave co-processing uses the ultrasonic and microwave co-extraction equipment currently on the market with a power above 90W. Products sold under the trade name "MAXIDIGEST MX 350" by the French PROLABO company and "Digesdahl digestion instrument" by the American Hach company.

In the present invention, the ultrasonic and microwave co-extraction should be understood as the simultaneous use of ultrasonic and microwave action to extract the target substance from the raw material.

(4) Centrifuge the ultrasonic and microwave cooperating extract in step (3), recover the supernatant, add ethanol aqueous solution to the centrifuged residue for washing, then centrifuge, combine the supernatant, and obtain a supernatant rich in flax lignans .

The centrifugation equipment used for this step is the same as that described previously.

(5) The clear liquid rich in flax lignans obtained in step (4) is concentrated under reduced pressure, and ethanol is recovered for recycling.

In the present invention, the said concentration under reduced pressure refers to the concentration carried out by removing the clear liquid solvent rich in flax lignans under a pressure of 1-5kPa.

The described decompression concentration equipment is currently sold in the market, such as products sold by Hangzhou Huihe Machinery Equipment Co., Ltd. under the trade name "vacuum decompression concentration tank", Jiangyin Jinfa Drying Equipment Co., Ltd., Jiangyin Suxin Drying Equipment Co., Ltd. Equipment Co., Ltd. or Wenzhou Lihong Light Industry Machinery Co., Ltd. sells the product under the trade name "spherical vacuum concentration tank".

(6) The vacuum concentration residue obtained in step (5) is spray-dried to obtain a flax lignan-containing extract.

According to a preferred embodiment of the present invention, flax lignans can be extracted from the shell-enriched part obtained by crushing the degummed flaxseed with a grinding wheel. The step of extracting flax lignans from the shell-rich part is the same as the step of extracting flax lignans from degummed flaxseeds described above.

According to another preferred embodiment of the present invention, in step (2), the obtained residue is washed with n-hexane at 5-20 parts by weight of n-hexane per part by weight of the residue.

According to another preferred embodiment of the present invention, the centrifugation is performed at a rotational speed of 2500-3500r/m for 15-25min.

Preferably, the centrifugation is carried out at a rotational speed of 3000r/m for 20min.

According to another preferred embodiment of the present invention, in step (3), ultrasonic and microwave co-extraction is carried out for 10-30 minutes. Preferably, in step (3), ultrasonic microwave co-extraction is carried out for 20 minutes.

According to another preferred embodiment of the present invention, in step (4), a 30%-60% (v/v) ethanol solution 3-6 times the weight of the residue is added for washing.

According to another preferred embodiment of the present invention, the residue concentrated under reduced pressure is spray-dried under the conditions of an inlet air temperature of 160-180°C and an outlet air temperature of 80-90°C or using hot air at a temperature of 80-90°C. dry.

The flax lignan-containing extract can be obtained by adopting the method of the present invention, and its flax lignan content is more than 10% based on the total weight of the extract (see accompanying drawing 2).

Flax lignan content is measured by HPLC, for example, using Waters2690 liquid chromatograph, select Symmetry C8 (150mm×2.1mm i.d., 5μm) reverse-phase chromatographic column, the scanning range of PAD is set at 200-400nm, column temperature 30°C, the injection volume is 10 μL. The mobile phase consisted of two solutions: (A) 1% acetic acid solution (v/v), (B) methanol. A linear gradient was used for elution (A:B, v/v), 0 min, 5:95; 40 min, 55:45; 60 min, 5:95. Flow rate 0.5mL/min. Mass spectrometry adopts positive ion and negative ion modes at the same time, and the operating parameters are:

The present invention also relates to the use of the flax lignan-containing extract in ingredients for baked products, beverages and snack foods.

[beneficial effect]

The present invention extracts flax lignans with the method of ultrasonic and microwave synergy, and its beneficial effects are as follows:

(1) Ultrasonic and microwave synergistic extraction of flax lignans has a high yield, which is more than 10% higher than the existing microwave extraction method, and the time is short. With the development of industrial scale equipment, the industrial application prospect of the present invention is bright;

(2) Using a lower solvent/material ratio, the extraction rate of the target product is high and the solvent is saved, killing two birds with one stone;

(3) Using degummed linseed or the husk-rich part of degummed linseed, especially the husk-rich part of degummed linseed as raw material, taking into account the utilization of other components in linseed, realizing efficient and comprehensive utilization of linseed, which is conducive to improving economic benefits and protect environment.

(4) The method proposed in the present invention can provide a useful reference for the extraction of other food functional factors.

【Description of drawings】

Figure 1. Process flow chart of ultrasonic and microwave co-extraction of flax lignans

Figure 2. HPLC analysis spectrum containing flax lignan extract

【Detailed ways】

Example 1

The wet degumming method was adopted, soaked for 60 min under the conditions of temperature 70°C, pH 6.0, and material-to-water ratio 1:7 (g/mL), and repeated degumming 4 times to obtain degummed flaxseed. After being dried with hot air at 60°C, it is pulverized by a pulverizer sold by Zhejiang Wenling Machinery Factory under the trade name "Chinese herbal medicine pulverizer", and sieved with a 60-mesh sieve. Weigh 500g of degummed linseed powder, add 6000mL of n-hexane, and stir for 2 hours in a closed container sold under the trade name "stainless steel reaction pot" by Wuxi Xishan Xuelang Chemical Equipment Factory at room temperature, and use Shanghai Anting Scientific Instrument Factory under the trade name The centrifuge sold by "desktop high-speed centrifuge" is centrifuged at 3000r/m for 20min, and the obtained residue is washed with 5000mL of n-hexane, then centrifuged at 3000r/m for 20min, and the residue is recovered to obtain degreased and degummed flaxseed powder Ventilate at a temperature of 70° C. for 1 hour to volatilize and remove n-hexane therein. At this time, the mass of degreased and degummed linseed powder is 300 g. Add 1200mL of 40% (v/v) ethanol aqueous solution to the degreased and degummed flaxseed powder, and mix well. In the device sold by Shanghai Xintuo Microwave Dissolution Testing Technology Co., Ltd. under the trade name "Ultrasonic-Microwave Synergistic Extraction/Reaction Apparatus", the synergistic effect was performed for 15 minutes under the conditions of ultrasonic power 300W and microwave power 1000W. Then carry out centrifugal separation with 3000r/m for 20min, reclaim the supernatant, add 1200mL 40% (v/v) ethanol aqueous solution to the residue, wash the residue, then carry out centrifugal separation with 3000r/m for 20min, merge the supernatant to obtain Flax lignan-rich serum. The combined supernatant was concentrated under reduced pressure at a pressure of 2 kPa, and ethanol was recovered for recycling. The residue was spray-dried using a spray dryer sold under the trade name "High Speed Centrifugal Spray Dryer" by Wuxi Linzhou Spray Dryer Factory under the conditions of 160°C inlet air and 90°C outlet air to obtain 32g flax lignan extract The product was analyzed by HPLC, and the SDG content of the flax lignan extract was determined to be 10.8% under the conditions specified in the instructions.

Example 2

The degummed flaxseed was degummed by a wet debonding method at a temperature of 70°C, a pH of 6.0, a material-to-water ratio of 1:7 (g/mL), soaking for 60 min each time, and debonding times 4 times. The shell-rich fraction was obtained after crushing by grinding wheel mill and grading by hydraulic vortex. The recovered shell-rich part was dried with hot air at 60°C, and then pulverized by a pulverizer with the trade name "Superfine Pulverizer for Heat-sensitive Materials" from Fujian Fengli Machinery Technology Co., Ltd., and passed through a 60-mesh sieve. Weigh 100g of degummed linseed husk powder, add 1000mL of n-hexane, and stir for 3 hours in a closed container sold under the trade name "stainless steel reaction pot" by Wuxi Xishan Xuelang Chemical Equipment Factory at room temperature. Centrifuge (3000r/m, 20min) separation in the centrifuge sold under the trade name "desktop high-speed centrifuge", then wash the residue with 500mL n-hexane, centrifuge (3000r/m, 20min), recover the residue, and obtain degreased and degummed flaxseed powder. Ventilate at 70° C. for 1 hour to volatilize and remove the n-hexane therein. At this time, the powder mass is 75 g. Add 600 mL of ethanol solution with a concentration of 40% (v/v) to the degreased and degummed flaxseed powder, and mix well. Under the condition of ultrasonic power of 90W and microwave power of 200W, a device sold under the trade name "Ultrasonic-Microwave Cooperative Extraction/Reaction Apparatus" by Shanghai Xintuo Microwave Dissolution Testing Technology Co., Ltd. was used for 500s. Centrifuge (3000r/m, 20min), recover the supernatant, add 500mL 40% (v/v) ethanol solution to the residue, wash the residue, centrifuge again (3000r/m, 20min), combine the supernatant to obtain Serum of flax lignans. Concentrate under reduced pressure in a device sold by Jiangyin Suxin Drying Equipment Co., Ltd. under the trade name "Spherical Vacuum Concentration Tank", and recover ethanol for recycling. Dry with hot air at 80°C to obtain 10.5 g of linseed hull powder, which was determined to contain 15.6% of secoisolaricoresinol diglucoside by HPLC analysis.

Claims (9)

1. A method of extracting flax lignans from flaxseed or shell, characterized in that the method may further comprise the steps: (1) degummed linseed is sieved with a 60-mesh sieve after crushing to obtain degummed linseed powder; (2) The degummed linseed powder obtained in step (1) is mixed with n-hexane according to the ratio of 1 part by weight and 10-20 parts by weight, and then degreased with n-hexane for 1-3h under stirring in a closed container at normal temperature, and then carry out centrifuged, the obtained residue is washed with n-hexane, and then centrifuged, the residue is degreased and degummed linseed powder, and then processed under reduced pressure to remove residual n-hexane; (3) Add 30-60% (v/v) concentration of ethanol aqueous solution to the degreased and degummed linseed powder obtained in step (2) according to the ratio of 4-8 parts by weight per part, and mix uniformly; 50-300W, the total microwave input power is 150-600W/g, and the microwave power is 50-1000W for ultrasonic and microwave collaborative extraction; (4) Centrifuge the ultrasonic and microwave cooperating extract in step (3), recover the supernatant, add ethanol aqueous solution to the centrifuged residue for washing, then centrifuge, combine the supernatant, and obtain a supernatant rich in flax lignans ; (5) The clear liquid rich in flax lignans obtained in step (4) is concentrated under reduced pressure, and ethanol is recovered for recycling; (6) The vacuum concentration residue obtained in step (5) is spray-dried to obtain a flax lignan-containing extract. 2. The method according to claim 1, characterized in that the flax lignans are extracted from the shell-enriched part obtained by crushing the degummed flaxseed with a grinding wheel. 3. The method according to claim 1, characterized in that in step (2), the obtained residue is washed with n-hexane according to 5-20 parts by weight of n-hexane per part by weight of the residue. 4. The method according to claim 1, characterized in that the centrifugation is carried out at a rotating speed of 2500-3500r/m for 15-25min. 5. The method according to claim 1, characterized in that step (3) carries out ultrasonic and microwave synergistic extraction for 10-30 minutes. 6. The method according to claim 1, characterized in that in step (4), 30%-60% (v/v) ethanol solution 3-6 times the weight of the residue is added for washing. 7. The method according to claim 1, characterized in that the residue concentrated under reduced pressure is spray-dried at an inlet air temperature of 160-180°C and an outlet air temperature of 80-90°C or at a temperature of 80-90°C. ℃ hot air for drying. 8. The flax lignan-containing extract obtained by the method according to any one of claims 1-7, characterized in that its flax lignan content is more than 10% based on the total weight of the extract. 9. The use of the flax lignan extract according to claim 8 in baked goods, beverages and snack food ingredients.

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