A sesame hulling method

Abstract

The present application relates to the technical field of food processing, and discloses a sesame peeling method, which comprises the steps of soaking and separating and removing sesame skin from pretreated sesame. The negative pressure treatment and microwave aging treatment are combined in the soaking process to replace the traditional alkali soaking process. The negative pressure treatment makes the sesame skin and kernel swell rapidly by absorbing water and penetrates into the sesame skin, which promotes the loosening or bursting of the sesame skin and reduces the tightness of the combination between the sesame skin and kernel. Then, the microwave aging treatment further reduces the combination between the sesame skin and kernel, realizes the separation between them, and is beneficial to the complete removal of the sesame skin in the subsequent process. The peeling method has high peeling rate, low sticking rate, low breaking rate of the sesame kernel after peeling, white color, unchanged content of sesame crude protein and other nutritional ingredients, and decreased content of crude fiber. Compared with the traditional alkali soaking process, the product obtained by the method of the present application has no alkali residue, good taste, and is friendly to the environment.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for peeling sesame seeds. Background Technology

[0002] Sesame, also known as sesame seed or flaxseed, is one of my country's major oil crops with high application value. It can be used for oil extraction and can also be eaten directly. The sesame husk accounts for 15-20% of the total seed weight and contains a large amount of oxalic acid and indigestible crude fiber. Oxalic acid's complexation with calcium ions reduces the body's absorption and utilization of calcium, and also gives sesame a bitter taste. The crude fiber hinders the digestion and absorption of sesame protein. After hulling, the oxalic acid content in sesame kernels can be reduced from 3% to 0.25%, significantly improving the digestibility of sesame protein. Therefore, thorough hulling of sesame seeds is a prerequisite for expanding their application in the food industry.

[0003] Currently, there are two main methods for peeling sesame seeds: dry and wet methods. Dry peeling involves roasting the sesame seeds to quickly remove moisture from the husks, making them brittle, and then removing the husks by impact. This method is simple, produces little pollution, and requires low investment, but has a low peeling rate, and the sesame kernels are prone to browning and yellowing during roasting, resulting in poor quality. Wet peeling involves first soaking the sesame seeds in hot alkaline water to expand and loosen the husks, then removing them through mechanical friction, followed by washing or sieving to separate the husks from the kernels. Wet peeling has a high peeling rate and produces high-quality sesame kernels, thus it is widely used in the production of food-grade sesame kernels. However, using hot alkaline water as a peeling agent poses a safety risk to food safety. Therefore, existing technology discloses a sesame peeling method that uses a combination of ultrasonic and enzymatic soaking in the soaking process instead of the traditional alkaline soaking process, resulting in a product with no alkaline residue and excellent taste. However, this technology requires the use of specific types of enzymes, such as cellulase and pectinase, each of which has its own unique applicable conditions and optimal pH and temperature, which limits its application range. In addition, since enzymes are difficult to purify, they generally contain other related enzymes, such as proteases, which will decompose the proteins in sesame to a certain extent, which is not conducive to improving the nutritional value of sesame. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing sesame peeling methods that combine ultrasonic and enzymatic hydrolysis in the soaking process, which result in the loss of sesame nutritional value and limited application scope, thereby providing a sesame peeling method.

[0005] To solve the above-mentioned technical problems, the present invention provides a sesame peeling method, which includes soaking pre-treated sesame seeds and separating and removing the sesame skins, wherein the soaking is performed by a combination of negative pressure and microwave cooking treatment.

[0006] Furthermore, the soaking includes the following steps:

[0007] The pretreated sesame seeds are soaked in water at 15-25°C and then subjected to negative pressure treatment.

[0008] The sesame seeds that have undergone negative pressure treatment are then microwaved for cooking.

[0009] Furthermore, in the negative pressure treatment, the pressure is -0.06 to -0.1 MPa, and the time is 8 to 10 minutes.

[0010] Furthermore, in the microwave curing process, the microwave power is 400-550W and the time is 5-8 minutes.

[0011] Furthermore, the separation and removal of sesame husks includes the following steps:

[0012] The sesame seeds that have undergone microwave cooking are subjected to preliminary ultrasonic dehulling.

[0013] The sesame seeds that have undergone preliminary peeling are then subjected to mechanical friction for further peeling; or,

[0014] The sesame seeds that have undergone microwave cooking are subjected to a preliminary peeling process involving mechanical friction.

[0015] The sesame seeds that have undergone initial peeling are then subjected to ultrasonic re-peeling.

[0016] Furthermore, the ultrasonic power of the ultrasound is 200-250W, and the duration is 5-10 minutes.

[0017] Furthermore, after removing the sesame husks, the process also includes drying the sesame seeds and separating the husks from the kernels.

[0018] Furthermore, the drying process involves drying the sesame seeds at 50–60°C until their moisture content is ≤8%.

[0019] Furthermore, the skin-kernel separation process involves sorting and removing the sesame skin from the dried sesame seeds to obtain sesame kernels.

[0020] The technical solution of the present invention has the following advantages:

[0021] 1. The sesame peeling method provided by this invention includes soaking pre-treated sesame seeds and separating and removing the sesame skin. The soaking process employs a combination of negative pressure treatment and microwave cooking, replacing the traditional alkaline soaking process. The negative pressure of this invention causes the sesame kernel to quickly absorb water and swell, penetrating the sesame skin and causing it to loosen or burst, reducing the tightness of the bond between the sesame skin and kernel. Microwave cooking further reduces the bond between the sesame skin and kernel, achieving separation and facilitating complete removal of the sesame skin in subsequent processes. This method results in a high peeling rate, low sticking rate, low breakage rate of the peeled sesame kernels, a white color, and unchanged content of nutrients such as crude protein, while reducing the crude fiber content. Compared to the traditional alkaline soaking process, the product obtained by this method has no alkaline residue, excellent taste, and is environmentally friendly.

[0022] 2. The sesame peeling method provided by the present invention uses cold water at 15-25°C to soak sesame seeds, which omits the step of preheating the soaking solution to 60-80°C in the traditional process, shortens the process flow, and saves energy. In addition, the cold water soaking process can also effectively avoid the problem of rapid increase in the yellow value of sesame kernels caused by raising the temperature, which is beneficial to improving the color of the product.

[0023] 3. The sesame peeling method provided by the present invention uses a combination of ultrasonic and mechanical peeling to effectively remove residual sesame husks from the surface of the sesame seeds, reduce the sesame husk sticking rate, and improve product quality.

[0024] 4. The sesame peeling method provided by this invention employs a specific negative pressure and microwave cooking process, which not only shortens the peeling time and improves the peeling efficiency and saves production costs, but also enhances the overall quality of the product, which is conducive to the implementation of industrial mass production. Detailed Implementation

[0025] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0026] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0027] Example 1

[0028] A method for peeling sesame seeds, the specific operation of which is as follows:

[0029] (1) Raw material pretreatment: Clean the sesame seeds, pour them into a water container, and add 20°C tap water directly. The amount of water should be enough to cover the sesame seeds in the container.

[0030] (2) Negative pressure process: Place the container containing sesame seeds into the vacuum drying oven, close the door of the vacuum drying oven to ensure that the drying oven forms a closed system; turn on the vacuum pump to evacuate the drying oven to a negative pressure state with a pressure of -0.08MPa, and maintain it for 9 minutes;

[0031] (3) Microwave cooking process: Take out the container containing sesame seeds that has been processed in step (2) and put it into the microwave oven. Set the microwave power to 450W and cook for 6 minutes.

[0032] (4) Ultrasonic process: Take out the container containing sesame seeds that has been treated in step (3), put it into an ultrasonic cell disruptor, and insert the probe of the cell disruptor into the liquid surface. Set the ultrasonic power to 220W and sonicate for 8 minutes.

[0033] (5) Peeling process: Take out the container containing sesame seeds that has been treated in step (4), and gently rub it with your hands to remove the sesame skins. Then take out the sesame seeds and drain the water.

[0034] (6) Drying process: Place the sesame seeds from step (5) into an oven at 55°C to dry them so that the moisture content of the sesame seeds is 8wt%.

[0035] (7) Separation of skin and kernel: The sesame seeds from step (6) are screened using a wire mesh screen to remove the sesame skin and obtain white sesame kernels.

[0036] (8) Perform routine index testing on the sesame kernels from step (7), and pack the sesame kernels that meet the index into aluminum foil bags and store them at room temperature.

[0037] Example 2

[0038] A method for peeling sesame seeds, the specific operation of which is as follows:

[0039] (1) Raw material pretreatment: Clean the sesame seeds, pour them into a water container, and add tap water at 25°C directly. The amount of water should be enough to cover the sesame seeds in the container.

[0040] (2) Negative pressure process: Place the container containing sesame seeds into the vacuum drying oven, close the door of the vacuum drying oven to ensure that the drying oven forms a closed system; turn on the vacuum pump to evacuate the drying oven to a negative pressure state with a pressure of -0.06MPa, and maintain it for 10 minutes;

[0041] (3) Microwave cooking process: Take out the container containing sesame seeds that has been processed in step (2) and put it into the microwave oven. Set the microwave power to 550W and cook for 5 minutes.

[0042] (4) Ultrasonic process: Take out the container containing sesame seeds that has been treated in step (3), put it into an ultrasonic cell disruptor, and insert the probe of the cell disruptor into the liquid surface. Set the ultrasonic power to 250W and sonicate for 5 minutes.

[0043] (5) Peeling process: Take out the container containing sesame seeds that has been treated in step (4), transfer the sesame seeds and soaking liquid into a disc peeling machine, use the peeling machine to peel off the sesame skin, then take out the sesame seeds and drain the water.

[0044] (6) Drying process: The sesame seeds from step (5) are placed in a circulating steam flow at 60°C to dry, so that the moisture content of the sesame seeds is 5wt%.

[0045] (7) Separation of skin and kernel: The sesame seeds from step (6) are screened using an air separator to remove the sesame skin and obtain white sesame kernels.

[0046] (8) Perform routine index testing on the sesame kernels from step (7), and pack the sesame kernels that meet the index into aluminum foil bags and store them at room temperature.

[0047] Example 3

[0048] A method for peeling sesame seeds, the specific operation of which is as follows:

[0049] (1) Raw material pretreatment: Clean the sesame seeds, pour them into a water container, and add 15℃ tap water directly. The amount of water should be enough to cover the sesame seeds in the container.

[0050] (2) Negative pressure process: Place the container containing sesame seeds into the vacuum drying oven, close the door of the vacuum drying oven to ensure that the drying oven forms a closed system; turn on the vacuum pump to evacuate the drying oven to a negative pressure state with a pressure of -0.1MPa, and maintain it for 8 minutes;

[0051] (3) Microwave cooking process: Take out the container containing sesame seeds that has been processed in step (2) and put it into the microwave oven. Set the microwave power to 400W and cook for 8 minutes.

[0052] (4) Ultrasonic process: Take out the container containing sesame seeds that has been treated in step (3), put it into an ultrasonic cell disruptor, and insert the probe of the cell disruptor into the liquid surface. Set the ultrasonic power to 200W and sonicate for 10 minutes.

[0053] (5) Peeling process: Take out the container containing sesame seeds that has been treated in step (4), transfer the sesame seeds and soaking liquid into a spiral peeling machine, use the peeling machine to peel off the sesame skin, then take out the sesame seeds and drain the water.

[0054] (6) Drying process: The sesame seeds from step (5) are placed in a circulating steam flow at 50°C to dry, so that the moisture content of the sesame seeds is 6wt%.

[0055] (7) Separation of skin and kernel: The sesame seeds from step (6) are screened using an air separator to remove the sesame skin and obtain white sesame kernels.

[0056] (8) Perform routine index testing on the sesame kernels from step (7), and pack the sesame kernels that meet the index into aluminum foil bags and store them at room temperature.

[0057] Comparative Example 1

[0058] A method for peeling sesame seeds, the specific operation of which is as follows:

[0059] (1) Raw material pretreatment: Clean the sesame seeds, pour them into a water container, and add 20°C tap water directly. The amount of water should be enough to cover the sesame seeds in the container.

[0060] (2) Negative pressure process: Place the container containing sesame seeds into the vacuum drying oven, close the door of the vacuum drying oven to ensure that the drying oven forms a closed system; turn on the vacuum pump to evacuate the drying oven to a negative pressure state with a pressure of -0.08MPa, and maintain it for 9 minutes;

[0061] (3) Ultrasonic process: Take out the container containing sesame seeds that has been treated in step (2), put it into an ultrasonic cell disruptor, and insert the probe of the cell disruptor into the liquid surface. Set the ultrasonic power to 220W and sonicate for 8 minutes.

[0062] (4) Peeling process: Take out the container containing sesame seeds that has been treated in step (3), and gently rub it with your hands to remove the sesame skins. Then take out the sesame seeds and drain the water.

[0063] (5) Drying process: Place the sesame seeds from step (4) into an oven at 55°C to dry them so that the moisture content of the sesame seeds is 8wt%.

[0064] (6) Separation of skin and kernel: The sesame seeds from step (5) are sieved using a wire mesh screen to remove the sesame skin and obtain white sesame kernels.

[0065] Experimental Example

[0066] The sesame kernels from Examples 1-3 and Comparative Example 1 were subjected to routine index tests. Crude protein content was determined according to GB / T14489.2-2008, and crude fiber content was determined according to GB / T 5515-2008. The peeling rate was calculated based on the total number of sesame kernels before peeling and the number of kernels with husks remaining after peeling. The breakage rate was calculated based on the total number of sesame kernels before peeling and the number of broken sesame kernels after peeling. The specific calculation formulas are as follows:

[0067] Peeling rate = (1 - S_sticky_peel / S_total) × 100%, damage rate = S_damaged / S_total × 100%, where S_total is the total number of sesame seeds before peeling, S_sticky_peel is the number of seeds with sticky peel after peeling, and S_damaged is the number of damaged sesame seeds after peeling.

[0068] The results of crude protein and crude cellulose content determination showed that the crude protein content of the peeled sesame seeds obtained by the method of the present invention and Comparative Example 1 remained unchanged before and after peeling, while the crude cellulose content decreased after peeling. The peeling rate and breakage rate results are shown in Table 1 below.

[0069] Table 1. Sesame peeling rate and breakage rate obtained by different methods.

[0070] Example 1 99.93 0.06 Example 2 99.85 0.08 Example 3 99.82 0.09 Comparative Example 1 82.5 0.1

[0071] As can be seen from the data comparison in the table above, the soaking process of the present invention, which combines negative pressure and microwave cooking, significantly improves the peeling rate of sesame seeds and results in a very low breakage rate of sesame kernels.

[0072] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for removing the husks from sesame seeds, comprising the steps of soaking pre-treated sesame seeds and separating and removing the sesame husks, characterized in that, The soaking process employs a combination of negative pressure and microwave curing. In the negative pressure treatment, the pressure is -0.06 to -0.1 MPa, and the time is 8 to 10 minutes. In the microwave curing process, the microwave power is 400-550W and the time is 5-8 minutes. The soaking process includes the following steps: The pretreated sesame seeds are soaked in water at 15-25°C and then subjected to negative pressure treatment. The sesame seeds that have undergone negative pressure treatment are then microwaved for cooking. The process of separating and removing sesame husks includes the following steps: The sesame seeds that have undergone microwave cooking are subjected to preliminary ultrasonic dehulling. The sesame seeds that have undergone preliminary peeling are then subjected to mechanical friction for further peeling; or, The sesame seeds that have undergone microwave cooking are subjected to a preliminary peeling process involving mechanical friction. The sesame seeds that have undergone initial peeling are then subjected to ultrasonic re-peeling. The ultrasonic power of the ultrasound is 200-250W, and the duration is 5-10 minutes.

2. The peeling method according to claim 1, characterized in that, After removing the sesame husks, the process also includes drying the sesame seeds and separating the husks from the kernels.

3. The peeling method according to claim 2, characterized in that, The drying process involves drying the sesame seeds at 50–60°C until their moisture content is ≤8%.

4. The peeling method according to claim 2 or 3, characterized in that, The process of separating the sesame seeds from their skin involves sorting the dried sesame seeds to remove the sesame skin and obtain the sesame kernels.