Method for peeling peganum harmala seeds

Abstract

The application provides a peeling method of blueberry kernels, which comprises the following steps: first, soaking dry blueberry kernels in acid with a preset concentration at a preset mass ratio, and continuously stirring; then, peeling the soaked blueberry kernels by using a peeling machine to obtain peeled blueberry kernels; finally, drying the obtained peeled blueberry kernels to obtain finished products. The application utilizes the interaction of lemon acid soaking, combined flushing of normal pressure and high pressure, and low-temperature baking, forms a gap between the blueberry kernels and the peel, realizes efficient peeling by using the combined flushing mode of normal pressure and high pressure, and finally, low-temperature drying, which not only avoids the heat damage of high temperature to the blueberry kernels, but also adapts to different specifications of blueberries, and the obtained blueberry products not only have a high peeling rate, but also have a good taste and a high nutritional value; meanwhile, the color of the obtained finished products is uniform, only a small amount of color is mixed, thereby improving the application of the blueberries in various mixed nutritional products or solid beverages.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food processing, and particularly relates to a method for peeling of Carya illinoinensis kernels. BACKGROUND

[0002] Carya illinoinensis (Wangenh.) K. Koch, belonging to Juglandaceae and Carya, is also called Carya illinoinensis (Wangenh.) K. Koch, and is originally from central and eastern North America and Mexican river valley. The kernel of Carya illinoinensis (Wangenh.) K. Koch is large, sweet and delicious, and is rich in nutrients, and is considered to be one of the most valuable North American nut varieties. The data of the United States Department of Agriculture in 2001 shows that the protein content of Carya illinoinensis (Wangenh.) K. Koch is 9.17%, the carbohydrate content is 13%, and Carya illinoinensis (Wangenh.) K. Koch also contains many vitamins and minerals, such as VA, VB, and phosphorus, zinc, manganese, etc. In addition, Carya illinoinensis (Wangenh.) K. Koch kernels also contain a large amount of phenols, tannins, and unsaturated fatty acids such as oleic acid and linoleic acid, and long-term consumption can reduce the probability of suffering from coronary heart disease, and improve the content of γ-tocopherol in the human body, so as to achieve the effects of anti-aging, anti-oxidation, and prevention of prostate cancer.

[0003] However, the phenolic substances contained in the pericarp of Juglandaceae can seriously reduce the solubility of the extracted protein and affect the functional properties of the protein. At the same time, the endocarp has astringent taste, which can seriously affect the eating taste of the related products. Therefore, removing the endocarp of Carya illinoinensis kernels to reduce the content of polyphenols and the astringent taste of Carya illinoinensis is an effective method for improving the taste and nutritional value of Carya illinoinensis.

[0004] At present, the methods for removing the endocarp of Carya illinoinensis mainly include mechanical peeling, alkali peeling and enzymatic peeling. The mechanical peeling refers to manually peeling the endocarp by a blade, and this method needs a large amount of manpower and material resources, and has low production efficiency. The alkali peeling usually first soaks Carya illinoinensis in a 0.5% sodium hydroxide solution at 70°C for 10 min, and then washes the endocarp of Carya illinoinensis with water, but the Carya illinoinensis treated by this method has a dark color, and the use of strong alkali has certain safety hazards, and the Carya illinoinensis after peeling has a certain alkali taste. The peeling conditions of the enzymatic peeling are relatively mild, and the quality of the obtained product is better, but the use of enzymes has strict requirements on the reaction conditions.

[0005] The blueberry is peeled to develop a new product, and the related patent has been disclosed. The patent with the application number CN202310342187.2 discloses a preparation method of blueberry oil and blueberry protein beverage. The blueberry kernel is peeled by using an enzyme method. The specific process is as follows: the blueberry kernel is soaked in a phosphate buffer solution with a concentration of 10-25 mM and a pH of 5.0-7.5 according to a solid-liquid ratio of 1:5-1:10, and is uniformly mixed by stirring; cellulase, pectinase and protease are added according to a mass ratio of 1:0.75-3:2-5, and the blueberry kernel is enzymolyzed at a temperature of 44-45 DEG C for 120-180 min, and is stirred to remove the blueberry peel; the protease is a composite of alkaline protease and papain. The peeling method is realized by adding multiple enzymes. First, the types of enzymes used are multiple, and each enzyme has a suitable working environment, so the reaction conditions are relatively harsh. Second, the use of multiple enzymes greatly increases the production cost. In addition, the peeling method affects the taste of the blueberry.

[0006] Therefore, it is necessary to design an improved peeling method for blueberry kernels to solve the above problems. SUMMARY

[0007] The purpose of the present application is to provide a peeling method for blueberry kernels, which utilizes the interaction of lemon acid soaking, combined flushing of normal pressure and high pressure, and low-temperature baking to make the obtained finished blueberry products not only have a high peeling rate, but also have a good taste. At the same time, the color of the obtained finished products is uniform, and only a small amount of mixed color is present, thereby improving the application of the blueberry in various mixed nutritional products or solid beverages.

[0008] To achieve the above-mentioned purposes, the present application provides a peeling method for blueberry kernels, which comprises the following steps:

[0009] S1. Soak the dried blueberry kernels in an acid with a predetermined concentration according to a predetermined mass ratio, and continuously stir;

[0010] S2. Peel the blueberry kernels soaked in step S1 by using a peeling machine to obtain peeled blueberry kernels;

[0011] S3. Dry the peeled blueberry kernels obtained in step S2 to obtain finished products.

[0012] As a further improvement of the present application, in step S1, the acid with a predetermined concentration is lemon acid with a mass concentration of 2-6%.

[0013] As a further improvement of the present application, in step S1, the soaking temperature is 50-70 DEG C, and the soaking time is 20-50 min.

[0014] As a further improvement of the present application, in step S1, the mass ratio of the acid to the bingren kernels is (3-5):1.

[0015] As a further improvement of the present application, in step S2, the peeling machine peels the bingren kernels by first normal-pressure washing and then pressure washing.

[0016] As a further improvement of the present application, the normal-pressure washing has a washing time of 10-20 min.

[0017] As a further improvement of the present application, the pressure washing has a washing pressure of 0.2-0.4 MPa and a washing time of 20-40 min.

[0018] As a further improvement of the present application, in step S3, the baking temperature is 45-55℃ and the baking time is 10-12 h.

[0019] As a further improvement of the present application, the peeling machine is a walnut peeling machine.

[0020] As a further improvement of the present application, in step S3, the peeling rate of the obtained finished product is as high as 95%, the loss of nutritional components is as low as 1.70%, and the obtained bingren kernels are yellowish white and have good color.

[0021] The present application has the following advantages:

[0022] (1) The peeling method for bingren kernels provided by the present application first soaks the dried bingren kernels in citric acid with a suitable concentration and temperature for a proper time, so as to open the water channel between the bingren kernels and the pericarp, thereby forming a gap between the bingren kernels and the pericarp. Then, the bingren kernels are washed by the combined washing method of normal pressure and high pressure. First, the temperature difference between the soaking temperature and the normal-pressure cold water used for washing increases the hardness of the bingren kernels, avoiding the bingren kernels from being cracked by washing, and the washing force of the normal-pressure water preliminarily separates the pericarp from the bingren kernels. On this basis, the bingren kernels are washed by high-pressure water. Since the hardness of the bingren kernels is improved and the normal-pressure water preliminarily separates the pericarp from the bingren kernels, the high-pressure water can quickly remove the pericarp, with a high removal rate and good kernel integrity. Finally, low-temperature baking not only avoids thermal damage to the bingren kernels caused by high temperature, but also adapts to bingren kernels of different specifications and effectively preserves the aroma and nutritional value of the bingren kernel raw materials.

[0023] (2) The obtained bingren kernel finished product has a high peeling rate and solves the problem of bitter taste caused by the bingren pericarp. Meanwhile, the finished product has uniform color and only a small amount of mixed color, thereby improving the application of bingren kernels in various mixed nutritional products or solid beverages. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Figure for the finished product of the pistachio nut obtained in Example 1 and Comparative Examples 1-3 of the present application.

[0025] Figure 2 Figure for the finished product of the pistachio nut obtained in Examples 1-3 and Comparative Examples 4-5 of the present application.

[0026] Figure 3 Figure for the finished product of the pistachio nut obtained in Example 1, Examples 4-5 and Comparative Examples 6-7 of the present application.

[0027] Figure 4 Figure for the finished product of the pistachio nut obtained in Examples 5-8 and Comparative Examples 8-9 of the present application.

[0028] Figure 5 a Figure for the finished product of the pistachio nut obtained in Examples 9-12 of the present application; Figure 5 b Figure for the finished product of the pistachio nut obtained in Comparative Examples 10-15.

[0029] Figure 6 Figure for the finished product of the pistachio nut obtained in Example 1 and Comparative Examples 17-19 of the present application. DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be described in detail below with reference to the accompanying drawings and specific examples.

[0031] Here, it should also be noted that, in order to avoid the present application being obscured by unnecessary details, only structures and / or processing steps closely related to the solutions of the present application are shown in the accompanying drawings, and other details not closely related to the present application are omitted.

[0032] In addition, it should also be noted that the terms "comprise", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device.

[0033] The present application provides a peeling method for pistachio nuts, comprising the following steps:

[0034] S1. Soaking

[0035] Dry pistachio nuts are soaked in a preset concentration of acid at a preset mass ratio, and continuously stirred. The preset concentration of acid is citric acid with a mass concentration of 2-6%; the soaking temperature is 50-70℃, the soaking time is 20-50min; and the mass ratio of citric acid to pistachio nuts is (3-5):1.

[0036] In the process, the preferred full, dry and fresh birch nuts, dry birch nuts have a certain degree of hardness, not easy to soften in the subsequent soaking process, while the subsequent high pressure water washing under pressure conditions, can better guarantee the integrity of the birch nut particles. If the moisture of the birch nut is too large, low-temperature drying can be preferred.

[0037] Soaking at 50-70℃ can open the water channel between the birch nut and the peel, forming a gap between the birch nut and the peel to facilitate the subsequent peeling operation. When the soaking temperature is higher or the soaking time is longer, the acidity of the birch nut will increase, the taste will be poor, and the birch nut will be too soft. The subsequent water washing will cause the birch nut to be severely broken, resulting in increased loss.

[0038] S2. Peeling

[0039] The birch nuts soaked in step S1 are placed in a peeling machine, first washed under normal pressure (i.e. without pressure, referred to as normal pressure water) for 10-20 min, then pressurized to 0.2-0.4 MPa (referred to as high pressure water) for 20-40 min for peeling, obtaining peeled birch nuts with good texture, complete shape and good color. Normal pressure water and high pressure water are normal temperature water or cold water from a faucet.

[0040] The peeling machine used is a walnut peeling machine.

[0041] In the process, first, the temperature difference between the soaking temperature in step S1 and the normal pressure cold water used for washing can increase the hardness of the birch nut, avoiding the cracking of the birch nut by water washing; secondly, the washing force of the normal pressure water can preliminarily separate the peel and the nut of the birch nut. On this basis, high pressure water is used for washing. Since the hardness of the birch nut has been improved, and the peel and the nut of the birch nut have been preliminarily separated by the normal pressure water, the high pressure water can quickly remove the peel, while the peel removal rate is high and the nut integrity is good.

[0042] S3. Drying

[0043] The peeled birch nuts obtained in step S2 are dried at 50℃ for 10-12h to dry the moisture and enhance the flavor, obtaining the finished product. A relatively low temperature is selected for drying to avoid heat damage to the birch nuts and to help fully enhance the volatile flavor of the raw material.

[0044] The peeled rate of the finished product is 95%, the loss of nutritional ingredients is as low as 1.70%, and the obtained birch nuts are yellowish white with good color. After drying, it is sweet and crisp with a strong nutty flavor, but higher temperature and longer processing time will increase the sourness of the birch nuts.

[0045] The present application will be described in detail below through several embodiments.

[0046] Example 1

[0047] A method for peeling pecan kernels includes the following steps:

[0048] S1. Soaking

[0049] Dried pecan kernels are soaked in an acid of a predetermined concentration according to a predetermined mass ratio, while continuously stirring. The predetermined concentration of acid is 4% citric acid; the soaking temperature is 50℃, the soaking time is 30 minutes, and the mass ratio of citric acid to pecan kernels is 4:1.

[0050] S2. Peeling

[0051] Place the soaked pecan kernels from step S1 into a walnut peeling machine. First, rinse them under normal pressure (i.e., without pressure, called normal pressure water) for 15 minutes, then pressurize to 0.3 MPa (called high pressure water) and rinse for 30 minutes to remove the skin, thus obtaining peeled pecan kernels with good texture, intact shape, and good color.

[0052] S3. Drying

[0053] The peeled pecan kernels obtained in step S2 are dried at 50°C for 11 hours to remove moisture and enhance aroma, thus obtaining the finished product.

[0054] Comparative Examples 1-3

[0055] A method for peeling pecan kernels, which differs from Example 1 in that the acid used to soak the pecan kernels in step S1 is different, but the rest is roughly the same as in Example 1, and will not be described again here.

[0056] The pecan kernel products obtained in Example 1 and Comparative Examples 1-3 were tested, and the results are shown in Table 1. The loss of nutrients refers to the mass of solids (excluding the mass of the peel) that are peeled off along with the peel during the peeling process. In other words, the loss of nutrients refers to the reduction in the amount of solids other than the peel.

[0057] Table 1. Pecan kernel products obtained in Example 1 and Comparative Examples 1-3

[0058] Example Acid Peeling rate (%) Nutrient component loss (%) Example 1 Citric acid 83 4.83 Comparative Example 1 Malic acid 65 5.81 Comparative Example 2 Glacial acetic acid 60 7.71 Comparative Example 3 Lactic acid 30 8.11

[0059] As shown in Table 1, the peeling rate after soaking in citric acid in Example 1 was significantly higher than that of Comparative Examples 1-3. This indicates that citric acid has a better peeling effect. In addition, the pecans obtained in Example 1 have no sour taste, are sweet and crispy, and have a rich nutty flavor, with an excellent taste.

[0060] like Figure 1 The images shown are of the finished pecan kernels obtained in Example 1 and Comparative Examples 1-3 (top and bottom showing the front and back of the same pecan kernel).Figure 1 Further, the peeling rate of the lemon acid soaking is obviously higher than that of the malic acid, glacial acetic acid and lactic acid. This is probably because the lemon acid is easier to penetrate between the kernel and the peel of the bing cherries, so that the gap is formed between the kernel and the peel of the bing cherries. In addition, the color of the finished product obtained in Example 1 is better.

[0061] Example 2-3 and Comparative Example 4-5

[0062] A peeling method of the bing cherry kernel is different from that of Example 1 in that the mass concentration of the lemon acid in step S1 is different, and other aspects are substantially the same as those of Example 1, which will not be repeated here. The mass concentration of the lemon acid in Comparative Example 4 is 0, that is, soaking directly in water.

[0063] The bing cherry kernel finished products obtained in Examples 2-3 and Comparative Examples 4-5 are tested, and the results are shown in Table 2:

[0064] Table 2 Bing cherry kernel finished products obtained in Examples 2-3 and Comparative Examples 4-5

[0065] Example Concentration Peeling rate (%) Nutrient component loss (%) Example 1 4％ 83 4.83 Example 2 6％ 85 3.87 Example 3 2％ 70 3.90 Comparative Example 4 0 20 1.83 Comparative Example 5 8％ 86 5.93

[0066] As shown in Table 2, within a certain range, as the concentration of the lemon acid increases (Examples 1, 2 and 3), the peeling rate gradually increases, the loss of nutritional ingredients first increases and then decreases, and the bing cherry obtained has no sour taste and good taste. The effect of soaking in 6% lemon acid at 50°C for 30 minutes (Example 2) is better, and the bing cherry obtained has no sour taste, is sweet and crisp after drying, and has rich nutty flavor.

[0067] With further increase of the concentration of the lemon acid (Comparative Example 5), although the peeling rate is high, the bing cherry after treatment has obvious sour taste and relatively poor taste, which further affects its use value.

[0068] When soaking directly in water, the peeling rate of the bing cherry is only 20%, and the peeling effect is obviously poor, so that the bing cherry obtained has more bitter taste.

[0069] As shown in the figures of the bing cherry kernel finished products obtained in Examples 1-3 and Comparative Examples 4-5 (the same bing cherry kernel front and back), as shown in the figures, as the concentration of the lemon acid increases, the peeling effect is continuously improved, and when the mass concentration of the lemon acid is 4% and 6%, the peeling effect is good. Figure 2 Figure 2 When no lemon acid is added (Comparative Example 4), the peeling effect is obviously poor.

[0070] Example 4-5 and Comparative Example 6-7

[0071] Example 4-5 and Comparative Example 6-7

[0072] ​A peeling method of blueberry kernel is provided, which is different from example 1 in that the soaking temperature is different in step S1, and other steps are substantially the same as those in example 1, which will not be repeated here.

[0073] The finished blueberry kernel products obtained from examples 4-5 and comparative examples 6-7 were tested, and the results are shown in table 3:

[0074] Table 3: Finished blueberry kernel products obtained from examples 4-5 and comparative examples 6-7

[0075] Example Temperature (°C) Peeling rate (%) Nutrient component loss (%) Example 1 50 83 4.83 Example 4 60 88 2.92 Example 5 70 95 1.70 Comparative Example 6 80 93 5.91 Comparative Example 7 30 20 3.47

[0076] As can be seen from table 3, within a certain range, as the soaking temperature increases (examples 1, 4, 5), the peeling rate of blueberry gradually increases, and the loss of nutritional ingredients gradually decreases, which may be because as the soaking temperature increases, it can better open the water channel between the kernel and the peel of blueberry, forming a gap between the kernel and the peel, which is more conducive to subsequent peeling operation. Using 4% citric acid, soaking at 70°C for 30 min (example 5), the peeling effect of blueberry is the best, and the loss of nutritional ingredients is less.

[0077] As the soaking temperature further increases (comparative example 6), although the peeling rate is high, the loss of nutritional ingredients is large, which is mainly because when the soaking temperature is too high (comparative example 6), the kernel of blueberry will become too soft during soaking, and subsequent water washing will cause the kernel to be washed away in a large area, resulting in loss of nutritional ingredients. When the soaking temperature is low (comparative example 7), the peeling rate of blueberry is obviously lower.

[0078] As Figure 3 can be seen, it is further proved that as the soaking temperature increases, the peeling effect is continuously improved; but when the soaking temperature is too high (comparative example 6), the kernel of blueberry will become too soft during soaking, and subsequent water washing will cause the kernel to be washed away in a large area. When the soaking temperature is too low (comparative example 7), the peeling effect is obviously poor.

[0079] Examples 6-8 and comparative examples 8-9

[0080] A peeling method of blueberry kernel is provided, which is different from example 5 in that the soaking time is different in step S1, and other steps are substantially the same as those in example 5, which will not be repeated here.

[0081] The finished blueberry kernel products obtained from examples 6-8 and comparative examples 8-9 were tested, and the results are shown in table 4:

[0082] Table 4: Finished blueberry kernel products obtained from examples 6-8 and comparative examples 8-9

[0083] Example Time (min) Peeling rate (%) Nutrient component loss (%) Example 5 30 95 1.70 Example 6 40 92 1.82 Example 7 20 93 1.81 Example 8 50 90 2.42 Comparative Example 8 10 70 1.83 Comparative Example 9 60 88 2.92

[0084] As shown in Table 4, the peeling rate and the loss of nutritional components of the apricot kernel are basically close when the apricot kernel is soaked in 4% citric acid at 70°C for 30-50 min, the overall peeling rate is higher, and the loss of nutritional components is less. The peeling rate of Example 8 is slightly lower, and the loss of nutritional components is slightly higher. This may be because the apricot kernel has a tendency to soften when it is soaked for 50 min (at this time, the softness will not be washed away by subsequent water washing), the adhesion between the apricot kernel and the peel changes, and then the peeling efficiency and the loss of nutritional components are affected. Too long or too short soaking time affects the peeling rate and the loss of nutritional components of the apricot kernel.

[0085] As shown in Table 4, the peeling rate and the loss of nutritional components of the apricot kernel are basically close when the apricot kernel is soaked in 4% citric acid at 70°C for 30-50 min, the overall peeling rate is higher, and the loss of nutritional components is less. The peeling rate of Example 8 is slightly lower, and the loss of nutritional components is slightly higher. This may be because the apricot kernel has a tendency to soften when it is soaked for 50 min (at this time, the softness will not be washed away by subsequent water washing), the adhesion between the apricot kernel and the peel changes, and then the peeling efficiency and the loss of nutritional components are affected. Too long or too short soaking time affects the peeling rate and the loss of nutritional components of the apricot kernel. Figure 4 As shown in Table 4, the peeling rate and the loss of nutritional components of the apricot kernel are basically close when the apricot kernel is soaked in 4% citric acid at 70°C for 30-50 min, the overall peeling rate is higher, and the loss of nutritional components is less. The peeling rate of Example 8 is slightly lower, and the loss of nutritional components is slightly higher. This may be because the apricot kernel has a tendency to soften when it is soaked for 50 min (at this time, the softness will not be washed away by subsequent water washing), the adhesion between the apricot kernel and the peel changes, and then the peeling efficiency and the loss of nutritional components are affected. Too long or too short soaking time affects the peeling rate and the loss of nutritional components of the apricot kernel.

[0086] Examples 9-12 and Comparative Examples 10-15

[0087] A peeling method of apricot kernel, compared with Example 5, the difference is that in step S2, the time of normal pressure washing and high pressure washing and the pressure of high pressure washing are different, and the others are basically the same as Example 5, which will not be repeated here.

[0088] The apricot kernel products obtained in Examples 9-12 and Comparative Examples 10-15 were tested, and the results are shown in Table 5:

[0089] Table 5 Apricot kernel products obtained in Examples 9-12 and Comparative Examples 10-15

[0090]

[0091] As shown in Table 5, Figure 5 when the pressure of high pressure washing is unchanged, with the change of the time of normal pressure washing and high pressure washing within a certain range (Examples 5, 9, 10), the peeling rate and the loss of nutritional components fluctuate within a small range, the overall peeling rate is higher, and the loss of nutritional components is less.

[0092] When the time of normal pressure washing is unchanged, with the decrease of the pressure of high pressure water and the appropriate increase of the time of high pressure washing (Example 12), or with the increase of the pressure of high pressure water and the appropriate decrease of the time of high pressure washing (Example 11), the peeling rate decreases, the loss of nutritional components increases, and the overall peeling efficiency is higher.

[0093] When the pressure of the high-pressure washing is constant, the normal-pressure washing time is too short, the high-pressure water washing time is too long (Comparative Example 10) or the high-pressure water and the low-pressure water are washed for the same time (Comparative Example 11), all of which have a great influence on the result, which shows that only when the high-pressure water and the low-pressure water are washed for a time that is matched with each other, can the peeling rate be high and the loss of the nutritional value be reduced at the same time.

[0094] As shown in Comparative Example 12 and Comparative Example 13, when the pressure of the high-pressure water is too low (Comparative Example 12), the water has a small force on the pistachio nuts, so that the peeling rate is low. When the pressure of the high-pressure water is too high (Comparative Example 13), the pistachio nuts are easily broken, which causes a significant loss of the nutritional value.

[0095] As shown in Comparative Example 14 and Comparative Example 15, only the high-pressure water or the low-pressure water is used for washing, which has an influence on the result.

[0096] Example 13

[0097] A peeling method of pistachio nuts, compared with Example 5, is different in that in step S1, the mass concentration of citric acid is 6%, and the peeling washing time in step S2 is shortened to 20 min, specifically, the normal-pressure washing is 10 min and the high-pressure washing is 10 min, and other conditions are basically the same as those in Example 5, which will not be repeated here. The peeling rate of the finished pistachio nuts obtained in Example 13 is 94%, and the loss of the nutritional components is 1.92%, which is basically close to that in Example 5, which shows that by appropriately increasing the concentration of citric acid and appropriately reducing the washing time, basically the same peeling effect can be achieved.

[0098] Comparative Example 16

[0099] A peeling method of pistachio nuts, compared with Example 5, is different in that in step S1, the mass concentration of citric acid is 2%, the soaking temperature is 90℃, and the soaking time is 20 min, and other conditions are basically the same as those in Example 5, which will not be repeated here. The peeling effect of Comparative Example 16 is poor, and the finished product has a certain sour taste.

[0100] Comparative Example 17

[0101] A peeling method of pistachio nuts, compared with Example 5, is different in that in step S1, according to the processing method of pistachio nuts in Chen Yu's “Preparation, Screening, Identification and Application Research of Pistachio Protein and Lipid-lowering Protein Peptide”, the pistachio nuts are soaked in 0.5% sodium hydroxide for 10 min, and other conditions are basically the same as those in Example 5, which will not be repeated here. The alkali soaking peeling method of Comparative Example 17 makes the pistachio nuts have a darker color, and more pistachio skins remain in the gaps of the pistachio nuts, which is difficult to remove, thereby affecting the further application of the pistachio nuts.

[0102] Comparative Example 18

[0103] A method for peeling the kernel of the blue gene, compared with example 5, the difference is that in step S1, the blue gene is soaked in 0.5% hydrochloric acid for 10 min, and the others are basically the same as example 5, which will not be repeated here.

[0104] Comparative example 19

[0105] A method for peeling the kernel of the blue gene, compared with example 5, the difference is that in step S1, the blue gene is soaked in 0.5% hydrochloric acid for 10 min, and the others are basically the same as example 5, which will not be repeated here.

[0106] Comparative example 20

[0107] A method for peeling the kernel of the blue gene, compared with example 5, the difference is that in step S2, mechanical peeling is used, that is, manual peeling with a blade, and the others are basically the same as example 5. This method consumes a lot of manpower and material resources, and is not suitable for large-scale industrial production. At the same time, the peeling rate is low, and the blue gene is easily cut.

[0108] The finished product of the kernel of the blue gene obtained in comparative examples 17-19 was tested, and the results are shown in table 6:

[0109] Table 6 finished product of the kernel of the blue gene obtained in comparative examples 17-19

[0110] Example Peeling rate (%) Nutrient component loss (%) Example 5 95 1.70 Comparative Example 17 88 3.83 Comparative Example 18 65 4.25 Comparative Example 19 68 4.42

[0111] From table 6, Figure 6 It can be seen that the blue gene treated by sodium hydroxide (comparative example 17) has a high peeling rate, but the obtained blue gene has a strong odor and a dark color, which is not suitable for eating. The blue gene treated by hydrochloric acid (comparative example 18) and phosphoric acid (comparative example 19) not only has a low peeling rate, but also has a strong acid taste. At the same time, after soaking in strong acid and strong base, the treatment of the soaking solution is difficult and the cost is high.

[0112] Comparative example 21

[0113] A method for peeling the kernel of the blue gene, the kernel of the blue gene is placed in a peeling tank, then a peeling agent is added to the peeling tank and stirred uniformly, so that the mass concentration of the peeling agent is 0.9%, then steam is introduced into the peeling tank to heat to 90℃, and after 8 min of insulation, the peeling agent solution is discharged by opening the peeling tank, and then the kernel of the blue gene is moved to a washing container for washing to obtain the kernel of the blue gene after peeling and astringency removal; the peeling agent is composed of NaOH and disodium ethylenediaminetetraacetate in a mass ratio of 14:1. The peeling rate of the finished product of the kernel of the blue gene obtained in comparative example 21 is 93%, and the loss of nutritional ingredients is 7.27%. This is mainly because the kernel of the blue gene treated at 90℃ is soft and easy to break, and the loss is high in the subsequent processing process. The color of the obtained kernel of the blue gene is yellow brown.

[0114] Comparative Example 22

[0115] A peeling method of pistachio nuts, compared with Example 5, the difference is that in step S1, the pistachios are soaked in a peeling agent with a mass concentration of 0.75%, and the soaking agent is composed of NaOH and disodium ethylenediaminetetraacetate in a mass ratio of 11:1, and the other steps are basically the same as Example 5, which will not be repeated here. The peeling rate of the finished pistachio nuts obtained by Comparative Example 22 is 92%, and the loss of nutritional ingredients is 2.52%. Sodium hydroxide makes the pistachio nuts easy to peel, but the obtained pistachios have obvious odor and dark color, which is not suitable for consumption and further production process.

[0116] Comparative Example 23

[0117] A peeling method of pistachio nuts, which uses the method of Example 1 in the patent with the application number CN202010083790.X to peel the pistachios. This method is complicated, uses more chemical reagents, and has high production cost, which is not suitable for large-scale production.

[0118] In summary, the peeling method of pistachio nuts provided by the present application utilizes the interaction of citric acid soaking, combined flushing of normal pressure and high pressure, and low-temperature baking to form a gap between the pistachio nuts and the peel first, then realizes efficient peeling by using the combined flushing method of normal pressure and high pressure, and finally low-temperature drying. Not only does it avoid the thermal damage caused by high temperature to the pistachio nuts, but also it can adapt to pistachios of different specifications. The obtained finished pistachio products not only have high peeling rate, but also have good taste and high nutritional value. At the same time, the color of the finished product is uniform, only a small amount of color is mixed, thereby improving the application of pistachios in various mixed nutritional products or solid beverages.

[0119] The above examples are only used to illustrate the technical solutions of the present application and are not limited. Although the present application has been described 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 by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for peeling pecan kernels, characterized in that, Includes the following steps: S1. Soak dried pecan kernels in an acid of a preset concentration according to a preset mass ratio, while stirring continuously; the preset concentration of acid is citric acid with a mass concentration of 4%; the soaking temperature is 70℃, and the soaking time is 20-40 minutes. S2. Peel the pecan kernels soaked in step S1 using a peeling machine to obtain peeled pecan kernels; the peeling process involves first rinsing under normal pressure, followed by rinsing under pressure; the rinsing time under normal pressure is 15 minutes; the rinsing pressure under pressure is 0.3 MPa, and the rinsing time is 30 minutes. S3. Dry the peeled pecan kernels obtained in step S2 to obtain the finished product; In step S1, the mass ratio of citric acid to pecan kernels is (3-5):1; In step S3, the drying temperature is 50℃ and the drying time is 11 hours.

2. The method for peeling pecan kernels according to claim 1, characterized in that, The peeling machine mentioned is a walnut peeling machine.

3. The method for peeling pecan kernels according to claim 1, characterized in that, In step S3, the peeling rate of the finished product is as high as 95%, the loss of nutrients is as low as 1.70%, and the obtained pecan kernels are yellowish-white with a good color.

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