Rapeseed protein concentrate detoxification production method based on ethanol washing and physical passivation

Abstract

The invention relates to a rapeseed protein concentrate efficient detoxification production method based on ethanol washing and physical passivation, and belongs to the technical field of agricultural product processing. In order to solve the problems of incomplete detoxification and large loss of nutritional ingredients in the prior art, the invention provides a collaborative detoxification method which comprises the following steps: firstly, cleaning and flaking rapeseeds, then carrying out key physical passivation treatment, instantaneously passivating myrosinase at 110-125 DEG C, and preventing glucosinolate enzymolysis; then, ethanol is adopted to leach and extract oil, the wet meal is subjected to multistage counter-current extraction and washing with a 50-70% ethanol aqueous solution, and anti-nutritional factors such as thioglycoside, phytic acid and tannin are deeply removed at 70-75 DEG C; and finally, carrying out solid-liquid separation, secondary drying and desolventizing treatment to obtain a finished product. The method realizes detoxification in the whole process from source blocking to body removal, has high detoxification efficiency, can maximally retain protein nutrition, is safe and environment-friendly in process, and is suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of feed safety production, and particularly relates to a rapeseed protein concentrate detoxification production method based on ethanol washing and physical passivation. BACKGROUND

[0002] Rapeseed is the third largest oil crop in the world, and its cake protein content after oil extraction is as high as 35%-45%, which is a potential plant protein resource. However, rapeseed cake contains various anti-nutritional factors, which seriously restricts its application in high-value feed and food fields. These anti-nutritional factors mainly include: Sulfur glucosinolate: non-toxic by itself, but degraded into toxic substances such as isothiocyanate (ITC), oxazolidine sulfone (OZT) and nitrile under the action of endogenous myrosinase, resulting in animal goiter, liver damage and growth inhibition.

[0003] Phytic acid: a strong metal chelator, which significantly reduces the bioavailability of minerals (calcium, iron, zinc, etc.), and forms complexes with proteins to reduce protein digestibility.

[0004] Tannin: combined with protein to form insoluble complexes, reducing protein digestibility and affecting palatability.

[0005] Traditional detoxification methods have obvious limitations: simple heat treatment (such as baking, steaming and frying) can effectively passivate myrosinase, but cannot remove the existing sulfur glucosinolate, and improper treatment can easily lead to Maillard reaction, reducing protein digestibility; water washing method can remove part of the water-soluble anti-nutritional factors, but the water consumption is large, the protein loss is serious, and a large amount of high-COD wastewater is produced; chemical method (such as acid treatment, alkali treatment, ammonia treatment) may introduce new chemical residues, affecting product safety.

[0006] Therefore, it is a technical problem to be solved in the field to develop a green processing method that can efficiently and completely remove various anti-nutritional factors while maximizing the nutritional value of protein. SUMMARY

[0007] The purpose of the present application is to solve the problems existing in the prior art, and to try to combine physical heat passivation and ethanol washing modification technology innovatively to efficiently remove the anti-nutritional factors such as sulfur glucosinolate, phytic acid and tannin in rapeseed and its cake, and to prepare safe and nutritious rapeseed protein concentrate, which can be used as high-quality feed protein raw material or further processed into food-grade protein ingredients, that is, to propose a rapeseed protein concentrate detoxification production method based on ethanol washing and physical passivation.

[0008] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: The method for producing rapeseed protein concentrate detoxification based on ethanol washing and physical passivation comprises the following steps: a) cleaning, conditioning and softening the rapeseed raw material; b) physical passivation pretreatment of the material after rolling, by instant high temperature and high pressure treatment to make the material temperature reach 110-125℃ and maintain for 30-150 seconds to completely passivate myrosinase; c) using ethanol with a concentration of 85%-95% to extract oil from the physically passivated material to obtain wet meal; d) ethanol washing modification detoxification treatment of the wet meal, using washing liquid for multi-stage countercurrent extraction, with extraction temperature controlled at 70-75℃; e) solid-liquid separation, drying and desolventization treatment of the detoxified material to obtain rapeseed protein concentrate finished product.

[0009] Preferably, the a) specifically comprises the following steps: Cleaning and magnetic separation: the rapeseed is first cleaned of impurities by a vibrating screen and a stone removal machine, and then metal foreign matter is removed by a magnetic separator; Conditioning and softening: the cleaned rapeseed enters a conditioning tower, appropriate amount of direct steam is introduced, the moisture is adjusted to 9%-12%, the temperature is adjusted to 50-60℃, and the softening time is 20-40 minutes, which is beneficial to subsequent rolling; Rolling: the softened rapeseed is rolled into a thickness of 0.25-0.35mm by a rolling machine to destroy the cell structure and increase the specific surface area.

[0010] Preferably, the physical passivation pretreatment in the b) means that the material after rolling is sent to a double screw extrusion expander, by adjusting the barrel temperature, screw speed and die pressure, the material is subjected to 110-125℃ (high temperature), 1.5-3.5MPa (high pressure) and high shear action for 30-150 seconds (instantaneously). This step must ensure that the core temperature of the material reaches and maintains in the above range, so that: completely and irreversibly passivate endogenous myrosinase (enzyme activity residual rate <3%).

[0011] destroy the rapeseed cell wall to fully expose the anti-nutritional factors embedded in the cells.

[0012] moderately denature the protein to form a porous structure, which is beneficial to subsequent solvent penetration and extraction.

[0013] Further, the moisture of the material entering the double screw extrusion expander is controlled at 15%-20%, and the outlet material temperature is monitored at ≥110℃.

[0014] Preferably, the c) operation process is as follows: the physical passivated material is transported to a leaching device (such as a ring leaching device or a flat rotating leaching device), and 85-95wt% of edible grade ethanol is used as a solvent to perform countercurrent leaching at 50-60℃ for 30-50 minutes; after leaching, mixed oil (to be sent to an evaporation system to recover ethanol and crude oil) and wet meal containing about 25-35wt% ethanol are obtained.

[0015] Preferably, the d) operation process is as follows: the leached wet meal is transported to a multi-stage countercurrent extraction washing system, and fresh washing liquid is added from the last stage of the extraction tank to contact the material containing the least toxic substances; gradually moving forward, the most concentrated washing liquid is in contact with the new material containing the most toxic substances to maximize the mass transfer driving force, and the extraction temperature is controlled at 70-75℃.

[0016] Further, the washing liquid is an ethanol aqueous solution with an ethanol concentration of 50-70wt%, in this concentration range, it can effectively dissolve polar substances such as glucosinolates and tannins, and reduce the loss of protein dissolution, and the pH value of the ethanol-aqueous solution is adjusted to be in the range of 4.5 to 7.0.

[0017] Further, the multi-stage countercurrent extraction washing system is a 3-stage or 4-stage countercurrent extraction washing system, and the total liquid-solid ratio (solvent to material ratio v / w) of the system is 3-5:1, and the extraction time of each stage is 15-25 minutes.

[0018] Preferably, the e) includes the following steps: Solid-liquid separation: the extracted slurry is subjected to high-efficiency solid-liquid separation by a horizontal screw sedimentation centrifuge or a plate-frame filter press to obtain detoxified wet meal and waste liquid rich in anti-nutritional factors (to be sent to an ethanol recovery tower).

[0019] Drying: the detoxified wet meal is subjected to a two-stage drying system. First, a steam tube bundle dryer or a fluidized bed dryer is used for primary drying (temperature 80-90℃) to rapidly reduce the moisture content from about 50% to about 20%; then a vacuum belt dryer or a low-temperature air flow dryer is used for secondary drying (temperature ≤70℃) to control the final product moisture content at ≤10%. This combined drying strategy can effectively prevent protein from overheating and denaturation.

[0020] Desolventization and flavor improvement: the dried material is subjected to a "breakout machine" (a device integrating mild extrusion, shearing and hot air treatment) at 80-90℃ for 5-10 minutes to completely remove residual trace ethanol (to ensure that the residual amount is <50ppm), while improving the color and flavor of the product and eliminating beany odor.

[0021] Cooling and packaging: after cooling and screening, the product is metered and packaged.

[0022] The drying process adopts two-stage drying: the first-stage drying temperature is 80-90℃, and the second-stage drying temperature is ≤70℃, so that the moisture content of the final product is ≤10%.

[0023] Preferably, in e), the desolventizing treatment is performed in a desolventizing machine at a temperature of 80-90℃ for 5-10 minutes, so that the residual ethanol in the product is less than 50ppm.

[0024] The present application also provides a rapeseed protein concentrate produced by the above method, which has a total glucosinolate content (dry basis) ≤25μmol / g, an isothiocyanate content ≤2.0mg / g, an oxazolidine sulfone content ≤2.5mg / g, a crude protein content ≥40%, and a residual ethanol content ≤50ppm.

[0025] Compared with the prior art, the present application has the following advantages: 1. The present application initiates a synergistic detoxification mechanism of physical passivation and ethanol washing extraction, which cuts off the path of glucosinolate conversion into toxic substances from the source; and the ethanol washing removes the glucosinolate and other water-soluble / ethanol-soluble anti-nutritional factors, achieving the whole-process control from "prevention" to "treatment".

[0026] 2. The present application has both high efficiency and selectivity: by optimizing the ethanol concentration, temperature, pH and countercurrent extraction process, the glucosinolate removal rate is >90% under the premise of high-efficiency detoxification, and the protein loss rate can be controlled to be <8%, which is much lower than that of the traditional water washing method (protein loss is usually >15%).

[0027] 3. The product of the present application has high nutritional value: the combination of mild physical passivation and low-temperature drying minimizes the excessive denaturation of protein and the Maillard reaction, the product has high protein dispersion index (PDI), balanced amino acid composition, and significantly improved digestion and utilization rate.

[0028] 4. The present application has high safety and environmental protection: the main solvent is ethanol, which is non-toxic and easy to recycle (recovery rate >98%), and recycling reduces cost and environmental burden. The product has no chemical reagent residues and is safe.

[0029] 5. The process of the present application has high integration degree and is suitable for industrialization: the pretreatment, oil extraction, detoxification and drying are integrated into a coherent automatic production line, which has high production efficiency and stable product quality.

[0030] 6. The product of the present application has wide application range: the obtained rapeseed protein concentrate has low toxin content, high nutritional value and good flavor, which can be used as a high-quality protein source for aquatic and livestock feed, and has potential application in the food industry after further refining. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0032] Example 1 (optimization scheme of the present application) The detoxification production method of rapeseed protein concentrate based on ethanol washing and physical passivation includes the following steps: a) cleaning, conditioning, softening and rolling the rapeseed raw material; b) performing physical passivation pretreatment on the rolled material, treating the material at a high temperature and high pressure for a short time to make the material temperature reach 110-125°C and maintain for 30-150 seconds, so as to completely passivate myrosinase; c) using ethanol with a concentration of 85%-95% to extract oil from the physically passivated material, to obtain wet meal; d) performing ethanol washing modification detoxification treatment on the wet meal, using washing liquid to perform multi-stage countercurrent extraction, and controlling the extraction temperature at 70-75°C; e) performing solid-liquid separation, drying and desolventization treatment on the detoxified material, to obtain rapeseed protein concentrate finished product.

[0033] Process parameters: extrusion passivation temperature 115°C, moisture 18%; 60% ethanol, 3-stage countercurrent extraction (pH 5.0, 72°C); two-stage drying (85°C→65°C).

[0034] Example 2 (intensified extraction scheme) Process parameters: extrusion passivation temperature 118°C; 70% ethanol, 4-stage countercurrent extraction (75°C).

[0035] Compared with Example 1, higher ethanol concentration and extraction stages bring better glucosinolate and tannin removal effect, because the mass transfer driving force is greater. However, the phytate removal rate decreases slightly, because higher ethanol concentration and pH environment are not conducive to the dissolution of phytate; at the same time, slightly higher treatment intensity leads to a slight decrease in PDI.

[0036] Comparative Example 1 (without physical passivation) Based on Example 1, the process parameters are changed: skip the extrusion passivation step, and directly perform 60% ethanol extraction. This group of results reveals the core role of physical passivation. Without passivating myrosinase, the raw material is in contact with myrosinase during rolling and subsequent processing, and a large amount of ITC and OZT is generated by enzymatic hydrolysis. Ethanol washing can wash away the remaining glucosinolate, but cannot remove the generated ITC and OZT, resulting in extremely high toxicity of the product. This proves that "blocking enzymatic hydrolysis" is the premise of detoxification.

[0037] Comparative Example 2 (without ethanol washing) On the basis of Example 1, change the process parameters: only extrusion passivation (115℃), no subsequent ethanol washing. Physical passivation successfully prevents enzymatic hydrolysis (ITC / OZT is low), but glucosinolate bulk, phytic acid, tannin and other substances still exist in large quantities in the meal. This proves that ethanol washing is an indispensable core step of "removing the bulk of anti-nutritional factors".

[0038] Comparative Example 3 (traditional process) On the basis of Example 1, change the process parameters: traditional steaming and frying heat treatment (105℃) + water washing at room temperature. Insufficient temperature or time of traditional heat treatment leads to incomplete myrosinase passivation (ITC / OZT is still high). At the same time, water washing has low detoxification efficiency, incomplete glucosinolate removal, and causes large protein loss (lowest protein content). Protein is severely denatured due to overheating and Maillard reaction (lowest PDI). Overall, the double advantages of the present application in detoxification efficiency and nutrient retention are highlighted.

[0039] Comparative Example 4 (excessive physical passivation) On the basis of Example 1, change the process parameters: extrusion passivation temperature 135℃. Although the high temperature ensures the detoxification effect, it causes severe protein denaturation, carbonization, and Maillard reaction, resulting in a decrease in protein content and a sharp decrease in PDI, greatly reducing the nutritional value. It is proved that physical passivation needs to strike a balance between "effectiveness" and "moderation".

[0040] Comparative Example 5 (low ethanol concentration) On the basis of Example 1, change the process parameters: use 40% ethanol for extraction. Low concentration of ethanol, high proportion of water, although good solubility for polar substances such as phytic acid, but also a large amount of protein is dissolved, causing serious protein loss. In addition, the low concentration of ethanol is insufficient for glucosinolate extraction, resulting in incomplete detoxification.

[0041] Comparative Example 6 (single-stage extraction) On the basis of Example 1, change the process parameters: only single-stage extraction is used, and the total solvent-to-material ratio is the same as Example 1. Under the same solvent consumption, the mass transfer efficiency of single-stage extraction is much lower than that of countercurrent extraction. Countercurrent extraction always maintains the maximum concentration difference between the washing liquid and the material, driving the anti-nutritional factors to continuously transfer from the solid phase to the liquid phase. Single-stage extraction quickly reaches equilibrium, with low efficiency, proving the value of the countercurrent process design.

[0042] Comparative Example 7 (low extraction temperature) On the basis of Example 1, change the process parameters: extraction temperature 50℃. Temperature is a key factor affecting molecular diffusion rate and solubility. At low temperature, molecular motion is slow, and the rate and degree of solubility of glucosinolates, phytic acid and other substances from the protein matrix are significantly reduced, resulting in poor detoxification effect.

[0043] Comparative Example 8 (over-drying) Based on Example 1, the process parameters were changed: direct drying at 120℃ was used. High-temperature drying led to severe protein denaturation, aggregation, PDI dropped sharply, and digestion rate was greatly reduced. At the same time, a serious Maillard reaction occurred, resulting in a darker color and an unpleasant flavor of the product, and the commercial value decreased. This proves the importance of the low-temperature drying strategy of the present application to retain the functional properties of the protein.

[0044] The data of Examples 1-2 and Comparative Examples 1-8 are summarized in Table 1 below: Table 1. Effect of process parameters on product performance

[0045] Summary and mechanistic explanation: Effectiveness of the synergistic detoxification mechanism: The success of Examples 1 and 2, and the failure of Comparative Examples 1 and 2, together demonstrate that the dual synergistic mechanism of the present application, "physical passivation to block enzymatic digestion + ethanol washing to remove the bulk", is the key to efficient and complete detoxification. Both are indispensable.

[0046] Optimization window of process parameters: Physical passivation: a "best window" (110-125℃) is needed, too low (Comparative Example 3) enzyme activity remains, too high (Comparative Example 4) and nutrition is damaged.

[0047] Ethanol washing: ethanol concentration (50%-70%), extraction temperature (70-75℃) and countercurrent stages are the key to determine the efficiency and selectivity of detoxification. Too low concentration (Comparative Example 5) or too low temperature (Comparative Example 7) is inefficient; non-countercurrent mode (Comparative Example 6) has low resource utilization.

[0048] Core of nutrient retention: the entire process chain, from mild physical passivation to low-concentration ethanol extraction, to the final low-temperature drying, every link aims to minimize the damage to the protein structure. Any over-treatment of a link (such as Comparative Examples 4, 8) will lead to protein denaturation and a significant decrease in nutritional value.

[0049] The experimental data fully demonstrate that the process scheme provided by the present application achieves the best balance in terms of detoxification completeness, nutrient retention, and process economy, and is significantly superior to traditional processes and any single detoxification method.

[0050] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can make equivalent substitutions or changes within the technical scope disclosed by the present application, according to the technical scheme and inventive concept of the present application, which should be covered within the protection scope of the present application.

Claims

1. Process for the detoxification of a rapeseed protein concentrate based on ethanol washing and physical passivation, characterized in that, The method comprises the following steps: a) cleaning, conditioning and softening the rapeseed raw material; b) physical passivation pretreatment of the material after rolling, by instant high temperature and high pressure treatment to make the material temperature reach 110-125℃ and maintain for 30-150 seconds to completely passivate myrosinase; c) using ethanol with a concentration of 85%-95% to extract oil from the material after physical passivation to obtain wet meal; d) ethanol washing modification detoxification treatment of the wet meal, multi-stage countercurrent extraction with washing liquid, extraction temperature controlled at 70-75℃; e) solid-liquid separation, drying and desolventization treatment of the material after detoxification to obtain rapeseed protein concentrate product.

2. The method for the detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 1, characterized in that, The a) specifically comprises the following steps: Cleaning and magnetic separation: the rapeseed is first cleaned by a vibrating screen and a stone removing machine to remove impurities, and then a magnetic separator is used to remove metal foreign matters; Conditioning and softening: the cleaned rapeseed enters a conditioning tower, appropriate amount of direct steam is introduced, the moisture is adjusted to 9-12%, the temperature is adjusted to 50-60℃, and the softening time is 20-40 minutes, which is beneficial to subsequent rolling; Rolling: the softened rapeseed is rolled into a sheet with a thickness of 0.25-0.35mm by using a rolling machine to destroy the cell structure and increase the specific surface area.

3. The process for the detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 1, characterized by the fact that, The physical passivation pretreatment in b) refers to feeding the material after rolling into a double screw extruder, adjusting the barrel temperature, screw speed and die pressure to make the material experience 110-125℃, 1.5-3.5MPa and high shear for 30-150 seconds to completely passivate myrosinase.

4. The method for the detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 3, characterized by the fact that, The moisture of the material entering the double screw extruder is controlled at 15-20wt%; The outlet material temperature is monitored at ≥110℃.

5. The process for detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 1, characterized by that, The operation process of c) is as follows: the material after physical passivation is fed into an extractor, edible grade ethanol with a concentration of 85-95wt% is used as solvent, countercurrent extraction is carried out at 50-60℃, and the extraction time is 30-50 minutes; after extraction, mixed oil and wet meal containing about 25-35wt% ethanol are obtained.

6. The method for detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 1, characterized in that, The operation process of d) is as follows: the wet meal after extraction is fed into a multi-stage countercurrent extraction washing system, fresh washing liquid is added from the last stage of extraction tank to contact with the material containing the least toxic substances; gradually forward, the most concentrated washing liquid contacts with the new material containing the most toxic substances to maximize the mass transfer driving force, and the extraction temperature is controlled at 70-75℃.

7. The method for the detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 6, characterized in that, The washing liquid is an ethanol aqueous solution with an ethanol concentration of 50-70wt%, in this concentration range, it can effectively dissolve polar substances such as glucosinolate and tannin, and reduce the loss of protein dissolution, and the pH value of the ethanol-water solution is adjusted to be in the range of 4.5 to 7.

0.

8. The method for detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 6, characterized by that, The multi-stage countercurrent extraction washing system is a 3-stage or 4-stage countercurrent extraction washing system, the total liquid-solid ratio of the system is 3-5:1, and the extraction time of each stage is 15-25 minutes.

9. The method for detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 1, characterized in that, In e), the drying process adopts two-stage drying: the first stage drying temperature is 80-90℃, and the second stage drying temperature is ≤70℃, so that the moisture content of the final product is ≤10%.

10. The method for detoxification of rapeseed protein concentrate based on ethanol wash and physical passivation according to claim 1, characterized in that, In e), the desolventization treatment is carried out in a desolventizing machine, the temperature is 80-90℃, the time is 5-10 minutes, and the ethanol residue in the product is ensured to be less than 50ppm.

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