Macadamia nut shell and kernel separating and sterilizing method

Abstract

The invention discloses a shell and kernel separating and sterilizing method for macadamia nuts. The method comprises the following steps: removing green peels on the outermost layers of nuts, and reserving the nuts with hard wooden shells; and then, carrying out vacuum-pumping sealing treatment on the fruit shells, treating the fruit shells in ultrahigh-pressure equipment for several minutes under the pressure condition of about 600 MPa, and after the pressure is released, enabling the surfaces of the fruit shells not to have obvious cracks but the adhesion between the fruit shells and the kernels to be reduced, and mechanically opening the fruit shells by pressing to obtain complete kernels. After the ultrahigh pressure action, the shell structure is subjected to microscopic loosening, the adhesion between shells and kernels is obviously reduced, the surface of the shell is not obviously cracked, efficient separation of complete kernels can be realized through mild mechanical pressing, meanwhile, a remarkable sterilization effect is achieved, and the shelf life of products is prolonged. The process disclosed by the invention does not need high temperature or chemical additives, is simple and convenient to operate, can maintain the natural flavor and nutritional quality of the nuts, and has green, safe and good industrial application prospects.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a process for separating and sterilizing macadamia nut shells and kernels using ultra-high pressure treatment. Background Technology

[0003] The most distinctive feature of macadamia nuts is their extremely hard and dense shell, with a hardness exceeding 200 MPa. This characteristic offers advantages in preserving the flavor of the kernel and preventing external contamination, but it also presents significant challenges to separating the kernel from the shell. Current processing technologies mainly include traditional mechanical shelling methods, heat-assisted shelling methods, and atmospheric pressure physical pretreatment methods. Existing technologies generally suffer from the following problems: the shell is too hard for conventional methods to break; the kernel and shell are strongly adhered, leading to incomplete separation and poor kernel integrity; the lack of sterilization measures results in a short shelf life for the kernels, making them susceptible to fat oxidation or mold growth; and existing methods often result in flavor loss, nutrient degradation, or environmental inconvenience.

[0004] Therefore, there is an urgent need for a new processing technology that is green and environmentally friendly, can preserve the flavor and nutrition of the kernels, improve the efficiency of kernel-shell separation, and extend shelf life. Summary of the Invention

[0005] The purpose of this invention is to provide a process for separating the shell and kernel of macadamia nuts using ultra-high pressure treatment and extending their shelf life, thereby solving the problems of kernel breakage, difficulty in separating the shell and kernel, and short shelf life caused by traditional methods.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for separating and sterilizing macadamia nut shells and kernels includes the following steps:

[0008] (1) Remove the outer skin: Remove the outer green skin of the macadamia nut, leaving the woody hard shell;

[0009] (2) Vacuum sealing: Sealing and packaging the nuts in their shells;

[0010] (3) Ultra-high pressure treatment: The shelled nuts are placed in an ultra-high pressure treatment device and subjected to ultra-high pressure treatment under pressure medium conditions;

[0011] (4) Shelling and kernel extraction: After ultra-high pressure treatment, the shelled nuts are mechanically pressed open to obtain whole kernels;

[0012] (5) Kernel Packaging: Select whole kernels, lightly dry them, and then directly package them into food products to complete the production of the product.

[0013] Furthermore, in step (2), the sealed packaging is vacuum sealed.

[0014] Furthermore, in step (2), a high-pressure resistant composite film packaging bag is used for vacuum packaging, and the vacuum degree is controlled within the range of 0.08MPa-0.1MPa to avoid secondary contamination.

[0015] Furthermore, in step (3), the pressure of the ultra-high pressure treatment is 500-650 MPa, preferably 580-620 MPa.

[0016] Furthermore, in step (3), the ultra-high pressure treatment time is 3-10 min, preferably 5-7 min.

[0017] Furthermore, in step (3), the ultra-high pressure treatment temperature range is 15-20℃ to avoid adverse effects on the flavor and nutritional components of the nuts.

[0018] Furthermore, in step (3), the ultra-high pressure treatment medium is distilled water or other liquids that are safe to come into contact with food.

[0019] Furthermore, in step (4), when using a light extruder for mechanical pressing, the pressure should be maintained at 5-20 MPa, and the piston or pressure plate stroke is generally 20-50 mm to ensure that the shell cracks.

[0020] Furthermore, in step (4), when using a roller press for mechanical pressing, the roller spacing should be maintained at 5-15mm and the roller speed at 5-20rpm. Low speed reduces the impact on the kernels and improves the integrity rate.

[0021] The ultra-high pressure treatment reduces the adhesion between the shell and the kernel. While the shell surface does not crack after ultra-high pressure treatment, its hardness, toughness, and adhesion to the kernel decrease, making it easier to completely separate the kernel and remove it easily, thus improving the kernel's integrity. The ultra-high pressure treatment also has a sterilizing effect, extending the shelf life of the nuts.

[0022] Compared with existing technologies, this invention has the following advantages: Through ultra-high pressure processing, the adhesion between the shell and the kernel is effectively reduced, allowing the kernel to be easily separated and kept intact, avoiding the kernel breakage problem caused by traditional mechanical shelling; the entire processing is carried out at room temperature, without the need for high temperatures or chemical reagents, thus maximizing the preservation of the natural flavor and nutrients of the nuts; simultaneously, ultra-high pressure itself has a good sterilization effect, and combined with vacuum sealing packaging, it can significantly extend the shelf life of nuts and reduce the risk of fat oxidation and mold; this process is green and environmentally friendly, simple in procedure, and easy to promote industrially, and can be directly applied to the commercial production and sales of nuts. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0024] The invention will now be further described with reference to the accompanying drawings.

[0025] like Figure 1 As shown, a process for separating and sterilizing macadamia nut shells and kernels is described, and the following examples illustrate this process:

[0026] Example 1:

[0027] (1) Select macadamia nuts with uniform maturity, no mold, and no mechanical damage as raw materials, and control the moisture content of the raw materials to 10%. Keep the nuts clean and dry, and temporarily store them at room temperature of 20°C to avoid moisture.

[0028] A drum peeler is used to remove the outer green skin of the nuts. The drum speed is set to 30 rpm. The green skin of the nuts is removed by gentle friction, resulting in nuts with intact woody hard shells. The whole process does not cause mechanical damage to the hard shells.

[0029] (2) After removing the peel, place the nuts in a food-grade composite film bag that can withstand ultra-high pressure treatment and vacuum them. The vacuum degree is set to 0.09 MPa, and the packaging bag material can withstand a high pressure environment of 600 MPa. Place the vacuum-packed nuts in an environment of 22℃ for 45 minutes to ensure that the internal temperature of the nuts is uniform and to reduce the damage to the kernels caused by local heating.

[0030] (3) Place the sealed nuts into an ultra-high pressure treatment device, use distilled water as the pressure transmission medium, and treat at 600 MPa for 5 minutes, with the treatment temperature controlled at 18℃. The ultra-high pressure causes the shell structure to loosen microscopically, significantly reducing the adhesion between the shell and the kernel, while also achieving effective sterilization.

[0031] (4) After the nuts are processed under ultra-high pressure, they are broken open by a light squeezing mechanical method, so that the shell opens along the natural structural cracks and the whole kernel can be easily extracted. No chemical additives or secondary processing are required to obtain intact kernels.

[0032] (5) After the kernels are completely removed, they are controlled by low-temperature hot air drying. The moisture content of the kernels is adjusted to 4% under hot air conditions at 40℃. Then, they are directly packaged for food production.

[0033] Example 2:

[0034] Other conditions and operating steps are the same as in Example 1, except that in step (2) of Example 1: the vacuum degree is set to 0.08 MPa, in step (3): the pressure is set to 575 MPa, the processing time is set to 6.5 min, the processing temperature is set to 17.5 ℃, and in step (4): the shell is broken by an extruder with an extrusion pressure of 12.5 MPa and a stroke of 35 mm.

[0035] Example 3:

[0036] Other conditions and operating steps are the same as in Example 1, except that in step (2) of Example 1, the vacuum degree is set to 0.10 MPa, in step (3), the pressure is set to 650 MPa, the processing time is 10 min, the processing temperature is set to 20 ℃, the pressure medium is pure water, and in step (4), a roller press is used to break the shell, the roller spacing is 15 mm, and the roller speed is 20 rpm.

[0037] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be within the scope of protection of the present invention.

Claims

1. A method for separating and sterilizing macadamia nut shells and kernels, characterized in that, Includes the following steps: (1) Remove the outer skin: Remove the outer green skin of the macadamia nut, leaving the woody hard shell; (2) Vacuum sealing: Sealing and packaging the nuts in their shells; (3) Ultra-high pressure treatment: The shelled nuts are placed in an ultra-high pressure treatment device and subjected to ultra-high pressure treatment under pressure medium conditions; (4) Shelling and kernel extraction: After ultra-high pressure treatment, the shelled nuts are mechanically pressed open to obtain whole kernels; (5) Kernel Packaging: Select whole kernels, lightly dry them, and then directly package them into food products to complete the production of the product.

2. The method according to claim 1, characterized in that, In step (3), the pressure of the ultra-high pressure treatment is 500-650 MPa, preferably 580-620 MPa.

3. The method according to claim 1, characterized in that, In step (3), the ultra-high pressure treatment time is 3-10 min, preferably 5-7 min.

4. The method according to claim 1, characterized in that, In step (3), the ultra-high pressure treatment temperature range is 15-20℃.

5. The method according to any one of claims 1-4, characterized in that, In step (2), the sealed packaging is vacuum sealed.

6. The method according to any one of claims 4, characterized in that, In step (2), high-pressure resistant composite film packaging bags are used for vacuum packaging, and the vacuum degree is controlled within the range of 0.08MPa-0.1MPa.

7. The method according to any one of claims 1-4, characterized in that, In step (3), the ultra-high pressure treatment medium is distilled water or other liquids that are safe to come into contact with food.

8. The method according to any one of claims 1-4, characterized in that, In step (4), when using a light extruder for mechanical pressing, the pressure should be maintained at 5-20 MPa, and the piston or pressure plate stroke is generally 20-50 mm to ensure that the shell cracks.

9. The method according to any one of claims 1-4, characterized in that, In step (4), when using a roller press for mechanical pressing, the roller spacing should be maintained at 5-15mm and the roller speed at 5-20rpm. Low speed reduces the impact on the kernels and improves the integrity rate.

10. The method according to any one of claims 1-4, characterized in that, The ultra-high pressure treatment reduces the adhesion between the shell and the kernel. The shell surface does not crack after ultra-high pressure treatment, but the hardness, toughness and adhesion to the kernel decrease, making it easier to completely separate the kernel and remove it easily, thus improving the integrity of the kernel. The ultra-high pressure treatment also has a sterilization effect, which can extend the shelf life of nuts.

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