A method for high purity separation of quinoa germ and wheat core

Abstract

The application discloses a high-purity separation method for quinoa germ and core, and mainly comprises the following steps: removing impurities from raw grains, adjusting moisture, first rolling, low-temperature soaking, enzyme inactivation and drying, second rolling, and screening and separation. The obtained quinoa germ has a purity higher than 95%, a protein content of more than 40 wt%, and a fat content of more than 15 wt%, and the obtained quinoa core powder has a starch content of more than 70 wt%. The application can greatly improve the separation precision of quinoa germ, and can reduce energy consumption and nutrient loss compared with the whole grain crushing and screening. The obtained quinoa germ powder and quinoa core powder can be directly used for the processing of functional food, or used as raw materials for further separation of quinoa protein or starch, and compared with the direct extraction of protein or starch from quinoa whole grain powder, the yield is high, the workload is small, and the method is green and environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the quinoa processing technical field, more particularly to a high-purity separation method of quinoa germ and core. BACKGROUND

[0002] Quinoa is an ancient grain crop originated from the Andes region of South America, which has attracted worldwide attention due to its rich and unique nutritional composition. Compared with most cereal starches, quinoa starch has small starch granules and low amylose content, showing unique application potential in the fields of biodegradable films, microcapsule wall materials, and Pickering emulsions. Quinoa protein is one of the few high-quality plant protein resources, with a balanced proportion of essential amino acids. Patients with celiac disease have good tolerance to diets containing quinoa, which is considered as a grain substitute for gluten-allergic populations. Quinoa oil is rich in functional ingredients such as unsaturated fatty acids, phytosterols, and tocopherols, showing great development potential in the fields of functional foods and cosmetics.

[0003] Currently, quinoa protein or starch is obtained by separation and extraction from quinoa whole grain powder, which requires a large amount of solvent and has a low product yield. Quinoa seeds are approximately flat cylindrical in shape, mainly composed of central endosperm and surrounding embryo. The endosperm occupies most of the quinoa seed and contains a large number of starch granules; while the embryo is mainly composed of protein bodies and lipid bodies.

[0004] Patent CN108244329B discloses a production technology for separating and extracting protein powder from quinoa germ, wherein the quinoa germ is obtained by the following method: quinoa seeds are coarsely ground and crushed, large particles that have not been crushed are removed by passing through a 40-mesh sieve, starch that has been powdered is removed by passing through a 100-mesh sieve, skin and endosperm particles are removed by air selection, and the obtained product is considered as quinoa germ, which is used as raw material for the preparation of quinoa germ protein powder. The existing technology separates quinoa germ based on the difference in particle size and density between the embryo and endosperm of quinoa seeds after crushing, but the crushing and screening processes have high energy consumption, and the purity of the separated product is difficult to define.

[0005] Therefore, how to effectively separate the embryo rich in protein and fat and the core rich in starch from quinoa is a problem to be solved. SUMMARY

[0006] The present application aims to provide a high-purity separation method of quinoa germ and core, which is simple, easy to operate, and highly targeted, overcoming the shortcomings of high energy consumption, low separation precision, and low purity in the prior art of crushing whole grain to prepare quinoa germ powder. The protein content in the quinoa germ powder obtained by the present application is >40wt%, the fat content is >15wt%, and the starch content in the quinoa core powder is >70wt%.

[0007] To solve the above technical problems, the technical solution of the present application is:

[0008] A method for high-purity separation of quinoa germ and quinoa core, characterized in that it comprises the following steps:

[0009] 1) Taking unhulled quinoa as raw material, removing impurities and shriveled seeds, sieving, and retaining quinoa seeds with a particle size of 1.5-2.0 mm;

[0010] 2) Adding water to the obtained quinoa seeds for 6-8 h until the water content in the quinoa seeds reaches 16-18 wt%;

[0011] 3) Then, the quinoa seeds are rolled to remove the seed coat, and the quinoa kernels are separated from the husks and bran, with a peeling rate of more than 11 wt%; after sieving, clean and complete quinoa kernels are obtained;

[0012] 4) The obtained quinoa kernels are washed with water until no foam is generated, and then soaked in water at a temperature of 4-8℃ for 20-40 min until a gap appears between the germ and the core; after draining, the quinoa kernels are treated with superheated steam for 60-80 s to inactivate the enzymes, and then dried to a water content of less than 12 wt%;

[0013] 5) The dried quinoa kernels are rolled to remove the quinoa germ from the core, and then sieved to separate the quinoa germ and the core.

[0014] Further, the obtained quinoa germ is ground through a 40-mesh sieve to obtain quinoa germ powder, and the obtained core is ground and sieved through an 80-mesh or 100-mesh sieve to obtain quinoa core powder.

[0015] Preferably, in step 4), ice stirring or ultrasonic treatment is added during the soaking process, with an ultrasonic power of 100-200 w and an ultrasonic time of 10-15 min.

[0016] The present application uses unhulled quinoa as raw material, removes impurities and shriveled seeds in quinoa, sieves, and retains quinoa seeds with a particle size of 1.5-2.0 mm, in order to ensure the consistency of rolling precision, and the particle size is too small to be peeled in the same batch processing, and the particle size is too large to be crushed.

[0017] Then, the quinoa seeds are soaked in water for 6-8 h until the water content in the quinoa seeds reaches 16-18 wt%, and the water content is too low to make the quinoa seed embryo toughness insufficient, resulting in a low retention rate of quinoa germ in the first rolling process.

[0018] The first milling processing is carried out on the quinoa kernels after the quinoa kernels are moistened, and the quinoa kernel peeling rate is improved by the milling friction between the quinoa kernels and the sand roller and the collision friction between the quinoa kernels in the milling process, and the peeling rate is controlled to be greater than 11wt%, so that the quinoa kernel peeling rate is improved, and the outer skin of the quinoa embryo is destroyed at the same time, thereby facilitating the water absorption and separation of the embryo in the subsequent process. In the milling process, the integrity of the quinoa embryo is also preserved to a great extent, and the broken kernel rate is controlled to be less than 20wt%.

[0019] Peeling rate = (weight of quinoa kernels before milling - weight of quinoa kernels after milling) / weight of quinoa kernels * 100%,

[0020] Broken kernel rate = weight of broken kernels / weight of quinoa kernels after milling * 100%,

[0021] After the milling, the quinoa kernels, the skin and the bran are separated by using a winnowing system, and then the broken kernels in the quinoa kernels are removed by using a vibrating screen (the screen hole diameter is less than two-thirds of the average particle size of the quinoa kernels) to obtain clean and complete quinoa kernels.

[0022] The obtained quinoa kernels are soaked at a low temperature of 4-8℃ for 20-40min until a gap appears between the embryo and the core, and the low-temperature soaking is used to make the quinoa embryo absorb water and swell, and improve the morphological characteristics of the quinoa embryo closely adhering to the core. The temperature and time need to be strictly controlled to reduce the change of nutritional components caused by the germination of the kernels. In the soaking process, ice stirring or ultrasonic treatment (ultrasonic power 100-200w, ultrasonic time 10-15min) can be used to accelerate the water absorption of the embryo.

[0023] The quinoa is treated by using superheated steam in the present application, which can reduce the endogenous enzyme activity in the quinoa kernels, especially the embryo, and has a certain sterilization effect, which is helpful to improve the storage stability of the quinoa embryo and the quinoa core powder, and to maintain the nutritional quality as much as possible.

[0024] The quinoa kernels after low-temperature soaking are subjected to milling processing again, and the quinoa embryo is broken and separated under the premise of retaining the integrity of the outer endosperm structure as much as possible, and then sieving is carried out to obtain the quinoa embryo and the core. The purity of the obtained quinoa embryo is higher than 95%.

[0025] The obtained quinoa embryo is ground through a 40-mesh sieve to obtain quinoa embryo powder, and the obtained core is ground and sieved through an 80-mesh or 100-mesh sieve to obtain quinoa core powder, wherein the protein content in the quinoa embryo powder is >40wt%, the fat content is >15wt%, and the starch content in the quinoa core powder is >70wt%.

[0026] The beneficial effects of the present application are as follows:

[0027] The quinoa of the present application utilizes the embryo to absorb water and expand, and a method of separating and obtaining high-purity quinoa embryo by twice milling processing. The first milling processing fully removes the quinoa hull and seed coat. After the quinoa embryo absorbs water and expands at low temperature, the second milling processing separates the embryo and the core. The obtained quinoa embryo has a purity higher than 95%, and the separation precision of the embryo is greatly improved. The obtained quinoa embryo and core are relatively complete and not in powder form. Compared with the traditional method of crushing the whole quinoa and then screening the embryo, the method has high separation precision, low energy consumption and high efficiency, and avoids the loss of nutrients caused by incomplete separation of the quinoa embryo.

[0028] The present application can fully separate the quinoa embryo rich in protein and fat and the quinoa core powder rich in starch in the quinoa. The obtained quinoa embryo powder has a protein content of >40wt%, a fat content of >15wt%, and the quinoa core powder has a starch content of >70wt%. The quinoa embryo powder can be directly used for the processing of functional food, or used as a raw material for further separation of quinoa protein or starch. Compared with directly extracting protein or starch from quinoa whole grain powder, the method has high yield, less workload and is green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure is a photo of the quinoa rice obtained after the milling processing of the quinoa seeds of the embodiment of the present application.

[0030] Figure 2 The figure is a photo of the quinoa rice after low-temperature soaking of the embodiment of the present application.

[0031] Figure 3 The figure is a photo of the quinoa embryo obtained by the embodiment of the present application.

[0032] Figure 4 The figure is a photo of the quinoa core obtained by the embodiment of the present application. DETAILED DESCRIPTION

[0033] The present application will be further described below through specific embodiments, but the embodiments do not limit the protection scope of the present application.

[0034] Embodiment 1

[0035] 1) The dehulled quinoa is used as a raw material, and the impurities and shriveled grains are removed by air selection, and the full and uniform quinoa seeds with a particle size of 1.5-2.0 mm are retained;

[0036] 2) The initial water content of the quinoa seeds is measured to be 8.7wt%, and the quinoa is soaked for 8h to adjust the water content to 16.6wt%;

[0037] 3) The quinoa is subjected to milling processing by using a sand roller rice mill, so that the seed coat of the seeds is removed. The hull and bran are removed by air selection, and the broken rice is removed by passing through a screen with a pore size of 1.0 mm. Clean and complete quinoa rice is obtained, the peeling rate is 12.7wt%, and the broken rice rate is 9.8wt%.

[0038] 4) After the shelled quinoa kernels were washed with water for 3 times, they were soaked with water and a small amount of ice was added. An automatic stirrer was used for continuous stirring. After 25 min, it was observed that the embryo absorbed water and swelled, and was no longer too tightly connected with the core. It could be easily peeled off with a pair of tweezers. After draining, it was treated with 110°C superheated steam for 80 s, and then placed in a 55°C drying oven for air drying. After 2 hours, the moisture content reached 11.3 wt%;

[0039] 5) The dried quinoa kernels were subjected to milling again to make the quinoa embryo fall off from the kernel body, and then passed through a 20-mesh sieve to separate the quinoa embryo and the core.

[0040] The obtained quinoa embryo was ground and passed through a 40-mesh sieve to obtain quinoa embryo powder. The obtained core was ground and passed through an 80-mesh sieve to obtain quinoa core powder. Then the protein, fat and starch contents in the quinoa embryo powder and the quinoa core powder were measured, respectively. The specific results are shown in Table 1.

[0041] The protein content was determined according to GB5009.5-2016 first method, the fat content was determined according to GB5009.6-2016 second method, and the starch content was determined according to GB5009.9-2016 second method.

[0042] Example 2

[0043] 1) The shelled quinoa was used as raw material, and the impurities and shriveled kernels were removed by air selection. The quinoa kernels with a particle size of 1.5-2.0 mm were retained by passing through a round hole sieve;

[0044] 2) The initial water content of the quinoa was determined to be 9.9 wt%. The quinoa was soaked with water for 6 h to adjust the water content to 17.3 wt%.

[0045] 3) The quinoa was subjected to milling by a sand roller rice mill to make the seed coat fall off. The husks and chaff were removed by air selection, and the broken kernels were removed by passing through a sieve with a hole diameter of 1.0 mm. Clean and complete quinoa kernels were obtained, wherein the peeling rate was about 14.2 wt%, and the broken kernel rate was about 13.9 wt%.

[0046] 4) After the quinoa kernels were washed with water for 5 times, they were soaked with water for 30 min in a 6°C environment, and were treated with 200w ultrasonic wave for 10 min during the soaking. After draining, the quinoa kernels were treated with 120°C superheated steam for 70 s, and then placed in a 50°C drying oven for air drying. After 3 hours, the moisture content reached 10.1 wt%.

[0047] 5) The dried quinoa kernels were subjected to milling again to make the quinoa embryo fall off from the kernel body, and then passed through a 20-mesh sieve to separate the quinoa embryo and the core.

[0048] The obtained quinoa germ was ground to pass through a 40-mesh sieve to obtain quinoa germ powder, and the obtained quinoa core was ground to pass through a 100-mesh sieve to obtain quinoa core powder, and then the protein, fat and starch contents in the quinoa germ powder and the quinoa core powder were measured respectively, and the specific results are shown in Table 1.

[0049] The protein content was determined according to GB5009.5-2016 first method, the fat content was determined according to GB5009.6-2016 second method, and the starch content was determined according to GB5009.9-2016 second method.

[0050] Comparative Example 1

[0051] The unhulled quinoa was coarsely ground and then passed through a 40-mesh sieve and a 100-mesh sieve, and the 100-mesh sieve retentate was air-separated to remove the skin and large granular endosperm blocks, and the obtained product was regarded as quinoa germ. The 40-mesh sieve retentate, the 100-mesh sieve retentate and the 100-mesh sieve undersize were ground to pass through an 80-mesh sieve, and the nutritional composition of each component was determined. The protein content of the 100-mesh sieve retentate was the highest, which was 27.3wt%, but was significantly lower than the protein content of the obtained germ powder of the present application.

[0052] Table 1

[0053]

[0054] Figure 1 The photo is a quinoa kernel obtained after milling of quinoa seeds according to the embodiment of the present application. As can be seen from the photo, the outer skin of the quinoa germ is damaged while the quinoa seed coat is removed.

[0055] Figure 2 The photo is a quinoa kernel after low-temperature soaking according to the embodiment of the present application. As can be seen from the photo, the quinoa germ is water-absorbed and swelled, and a gap appears between the germ and the core.

[0056] Figure 3 The photo is a quinoa germ obtained according to the embodiment of the present application. As can be seen from the photo, the obtained quinoa germ is relatively complete.

[0057] Figure 4 The photo is a quinoa core obtained according to the embodiment of the present application. As can be seen from the photo, the obtained core is relatively complete.

[0058] As can be seen from Table 1, the protein and fat contents in the quinoa germ powder obtained by the present application are much higher than those in the quinoa germ powder obtained by using the traditional method.

[0059] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not to limit. Although the present application is explained in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the scope of the technical solutions of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A method for high purity separation of quinoa germ and quinoa core, characterized by, It comprises the following steps: 1) taking buckwheat with hull as raw material, removing impurities and shriveled seeds, sieving, and retaining buckwheat seeds with a particle size of 1.5-2.0 mm; 2) adding water to the obtained buckwheat seeds for 6-8 h until the water content in the buckwheat seeds reaches 16-18 wt%; 3) then, the buckwheat seeds are rolled to make the seed coat fall off, and the buckwheat kernels are separated from the hull and bran, with the control of the peeling rate being greater than 11 wt% and the broken kernel rate being lower than 20 wt%, and then sieving to obtain clean and complete buckwheat kernels; 4) the obtained buckwheat kernels are washed with water until no foam is generated, and then soaked in water with a temperature of 4-8℃ for 20-40 min until a gap appears between the embryo and the core, and then drained, and then treated with superheated steam for 60-80 s to inactivate the enzyme, and then dried until the water content in the buckwheat kernels is lower than 12 wt%; 5) the dried buckwheat kernels are rolled to make the buckwheat embryo fall off from the core, and then sieved to separate the buckwheat embryo from the core.

2. The method of claim 1, wherein the quinoa germ and bran are separated at a high purity. The obtained buckwheat embryo is ground through a 40-mesh sieve to obtain buckwheat embryo powder, and the obtained core is ground and then sieved through an 80-mesh or 100-mesh sieve to obtain buckwheat core powder.

3. The method of claim 1, wherein the quinoa germ and bran are separated at a high purity. In steps 3) and 5), the sieve hole diameter is less than two-thirds of the average particle size of the buckwheat kernels.

4. The method of claim 1, wherein the quinoa germ and bran are separated at a high purity. In step 4), ice stirring or ultrasonic treatment is added during the soaking process, wherein the ultrasonic power is 100-200 w and the ultrasonic time is 10-15 min.

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