Method for producing rice bran fermented pellet using solid fermentation

Abstract

The present invention relates to a method for producing fermented rice bran pellets that can be utilized as various materials by inoculating rice bran with a Bacillus licheniformis strain, fermenting it, and producing it into pellets, thereby having high amylase activity and enhanced storage stability, and to fermented rice bran pellets produced by said method.

Description

Technology Field

[0001] The present invention relates to Bacillus licheniformis (in sterilized and cooled rice bran) Bacillus licheniformis The present invention relates to a method for manufacturing fermented rice bran pellets and fermented rice bran pellets manufactured by the method, characterized by comprising the steps of: inoculating and mixing a strain culture solution and then fermenting it on a solid basis to produce a fermented rice bran product; and molding the fermented rice bran product produced by the method into pellets. The fermented rice bran pellets of the present invention have enhanced amylase activity with excellent heat resistance and high storage stability, so they can be utilized as various materials. Background Technology

[0002] Generally, rice consists of a husk layer, a bran layer, an embryo, and an endosperm. Brown rice is produced by removing the husk layer through the milling process, while white rice is obtained by milling brown rice to remove the bran, including the embryo, pericarp, seed coat, and aleurone layer. Rice bran is a byproduct generated during the milling of brown rice into white rice, containing the embryo; approximately 35,000 tons are produced annually in Korea.

[0003] Rice bran contains 14% moisture, 1–17% protein, 15–20% lipids, 7–10% ash, and is rich in carbohydrates and fiber. It is known that about 95% of various physiologically active substances are distributed in rice bran, while the remaining physiologically active substances are distributed in white rice.

[0004] As rice bran contains many bioactive substances, it exhibits a variety of physiological activities, such as heavy metal detoxification, anti-constipation, anti-cholesterol, skin beautification, antihypertensive, antihypertensive, and hangover relief.

[0005] Since the nutrients of rice are concentrated in the germ and bran, rice bran is a highly nutritious substance containing most of the nutrients in rice. However, due to its high lipid content, it is difficult to finely powder it, and it spoils very quickly. Consequently, it is mostly used as animal feed or fertilizer rather than being utilized in food or cosmetics. Therefore, research is needed to prevent spoilage during storage and to utilize the abundant nutrients, such as dietary fiber, found in rice bran as a food ingredient.

[0006] Korean Published Patent No. 2023-0064712 discloses a method for manufacturing rice bran powder, and Korean Registered Patent No. 1504909 discloses a method for stabilizing rice bran, but these methods differ from the method for manufacturing fermented rice bran pellets using solid fermentation according to the present invention. The problem to be solved

[0007] The present invention was devised in response to the above-mentioned needs, and the objective of the present invention is to manufacture fermented rice bran pellets that have excellent storage stability and can be utilized as a high-value-added material by utilizing rice bran, which has low storage capacity and utility.

[0008] In addition, another objective of the present invention is to provide fermented rice bran pellets with enhanced palatability and improved digestive function by optimizing manufacturing conditions such as rice bran pretreatment, strain selection, fermentation, and pelletization, thereby enhancing amylase activity with excellent heat resistance.

[0009] In addition, another objective of the present invention is to reduce feed costs while increasing the nutritional value of the feed and improving digestive efficiency using nutrients derived from rice bran when fermented rice bran pellets with excellent amylase activity are used as a feed additive.

[0010] In addition, another objective of the present invention is to provide fermented rice bran pellets that can be applied to high-quality processed foods by generating digestive enzymes with high palatability and nutritional value and excellent heat resistance. means of solving the problem

[0011] To solve the above problem, the present invention comprises the steps of (1) adding water to rice bran, sterilizing and cooling it; (2) adding Bacillus licheniformis ( Bacillus licheniformis The present invention provides a method for manufacturing fermented rice bran pellets, characterized by comprising the steps of: (3) inoculating and mixing a strain culture solution and then fermenting it to produce a fermented rice bran product; (2) drying the fermented rice bran product produced in step (2); and (4) molding the dried fermented rice bran product from step (3) into pellets.

[0012] In addition, the present invention provides a fermented rice bran pellet produced by the above method.

[0013] In addition, the present invention comprises (1) a step of adding water to rice bran, sterilizing and cooling it; (2) a step of adding Bacillus licheniformis (to the cooled rice bran from step (1) Bacillus licheniformis A method for enhancing the α-amylase activity and storage stability of a fermented rice bran pellet is provided, comprising the steps of: (3) preparing a fermented rice bran product by inoculating and mixing a strain culture solution and then fermenting it; (4) drying the fermented rice bran product prepared in step (2); and (5) forming the dried fermented rice bran product from step (3) into a pellet. Effects of the invention

[0014] Conventional rice bran is left unused after milling, resulting in reduced utility due to microbial contamination. However, in this invention, milled rice bran is hygienically sterilized and then molded into pellets, enabling long-term preservation and offering the advantage of easy application to various products.

[0015] In addition, the rice bran fermented pellets of the present invention contain a large amount of nutrients derived from rice bran, which can meet the nutritional needs of consumers, and can provide rice bran fermented pellets that are easy to apply to various processed foods due to their excellent palatability.

[0016] In addition, the rice bran fermented pellets of the present invention contain high-potency amylase, so they can be used as a raw material for enzyme foods by enhancing digestive function.

[0017] In addition, when the fermented rice bran pellets of the present invention are used as a feed additive, it is expected that they can contribute to reducing feed costs through the recycling of rice bran, a waste resource, and improve the digestive efficiency of animals due to the content of high-potency amylase. Specific details for implementing the invention

[0018] To achieve the objective of the present invention, the present invention

[0019] (1) A step of adding water to rice bran, sterilizing it, and cooling it;

[0020] (2) Bacillus licheniformis ( Bacillus licheniformis A step of producing a fermented rice bran product by inoculating and mixing a strain culture solution and then fermenting it;

[0021] (3) A step of drying the fermented rice bran product prepared in step (2) above; and

[0022] (4) A method for manufacturing fermented rice bran pellets is provided, characterized by including the step of forming the dried fermented rice bran product of step (3) into pellets.

[0023] In the method for manufacturing fermented rice bran pellets of the present invention, step (1) can preferably be performed by adding 1 to 3 times (v / w) of water relative to the rice bran, sterilizing at 90 to 100°C for 10 to 20 minutes, and cooling to 28 to 32°C, and more preferably by adding 2 times (v / w) of water relative to the rice bran, sterilizing at 95°C for 15 minutes, and cooling to 30°C. Sterilizing under the above conditions allows for the preparation of rice bran having a moisture content suitable for fermentation, without contamination by unwanted bacteria or off-flavors during subsequent fermentation.

[0024] In addition, in the method for manufacturing rice bran fermented pellets of the present invention, the rice bran fermented product of step (2) is preferably Bacillus licheniformis (in cooled rice bran) Bacillus licheniformisIt can be prepared by inoculating 4~6% (w / w) of a strain culture solution, mixing, and then solid-state fermenting at 28~32℃ for 40~56 hours, and more preferably, Bacillus licheniformis ( Bacillus licheniformis It can be prepared by inoculating 5% (w / w) of the strain culture solution, mixing, and then solid-state fermenting at 30°C for 48 hours. Fermenting under the above conditions resulted in a high increase in amylase activity, and it was possible to produce a fermented rice bran product with excellent quality and palatability, as it did not produce a fermented odor and had excellent flavor.

[0025] In addition, the above Bacillus licheniformis ( Bacillus licheniformis ) is Bacillus licheniformis( Bacillus licheniformis The KCTC1030 strain is a strain held by the National Institute of Biological Resources of the Korea Research Institute of Biotechnology and Bioengineering, and the inventor obtained the said strain from the National Institute of Biological Resources of the Korea Research Institute of Biotechnology and Bioengineering and used it to manufacture the rice bran fermentation pellets of the present invention. Through preliminary experiments, the inventor found that using the said specific strain to manufacture rice bran fermentation pellets resulted in excellent heat-resistant amylase production, and since the enzyme activity did not decrease even after subsequent heat treatment and pellet processing, the inventor selected the said strain as the optimal strain suitable for rice bran fermentation.

[0026] In addition, in the method for manufacturing rice bran fermented pellets of the present invention, the drying in step (3) can preferably be performed by drying the rice bran fermented product at 60 to 80°C until the moisture content reaches 10 to 15% (v / w), and more preferably by drying the rice bran fermented product at 70°C until the moisture content reaches 12% (v / w). Drying under such conditions allowed for effective drying by shortening the drying time without detecting E. coli in the final pellet product or affecting the quality of the rice bran fermented product.

[0027] In addition, in the method for manufacturing rice bran fermented pellets of the present invention, step (4) is preferably performed by feeding the dried rice bran fermented product into a pellet molding machine at 70 to 90°C. It can be molded into pellets with a size of 2 to 8 mm. Even when molded into pellets under the above conditions, it was possible to produce fermented rice bran pellets with excellent flavor and taste while maintaining the enzyme activity.

[0028] The method for manufacturing rice bran fermented pellets of the present invention, more specifically, is

[0029] (1) A step of adding 1 to 3 times (v / w) of water relative to rice bran, sterilizing at 90 to 100°C for 10 to 20 minutes, and cooling;

[0030] (2) Bacillus licheniformis ( Bacillus licheniformis A step of preparing a fermented rice bran product by inoculating and mixing a strain culture solution, followed by solid-state fermentation at 28–32℃ for 40–56 hours;

[0031] (3) A step of drying the fermented rice bran product prepared in step (2) at 60~80℃ until the moisture content becomes 10~15% (v / w); and

[0032] (4) The dried fermented rice bran from step (3) above is fed into a pellet molding machine at 70~90℃ It may include a step of forming into pellets of a size of 2 to 8 mm, and

[0033] More specifically,

[0034] (1) A step of adding twice the amount of water (v / w) relative to the rice bran, sterilizing at 95°C for 15 minutes, and cooling;

[0035] (2) Bacillus licheniformis ( Bacillus licheniformis A step of preparing a fermented rice bran product by inoculating and mixing a strain culture solution, followed by solid-state fermentation at 30℃ for 48 hours;

[0036] (3) A step of drying the fermented rice bran product prepared in step (2) at 70°C until the moisture content becomes 12% (v / w); and

[0037] (4) The dried fermented rice bran from step (3) above is fed into a pellet molding machine at 70~90℃ It may include a step of forming pellets of size 2 to 8 mm.

[0038] The present invention also provides a fermented rice bran pellet produced by the above method.

[0039] The present invention also,

[0040] (1) A step of adding water to rice bran, sterilizing it, and cooling it;

[0041] (2) Bacillus licheniformis ( Bacillus licheniformis A step of producing a fermented rice bran product by inoculating and mixing a strain culture solution and then fermenting it;

[0042] (3) A step of drying the fermented rice bran product prepared in step (2) above; and

[0043] (4) A method for improving the α-amylase activity and storage stability of rice bran fermentation pellets is provided, comprising the step of forming the dried rice bran fermented product of step (3) into pellets.

[0044] The method for enhancing the α-amylase activity and storage stability of rice bran fermented pellets according to the present invention, more specifically, is

[0045] (1) A step of adding 1 to 3 times (v / w) of water relative to rice bran, sterilizing at 90 to 100°C for 10 to 20 minutes, and cooling;

[0046] (2) Bacillus licheniformis ( Bacillus licheniformis A step of preparing a fermented rice bran product by inoculating and mixing a strain culture solution, followed by solid-state fermentation at 28–32℃ for 40–56 hours;

[0047] (3) A step of drying the fermented rice bran product prepared in step (2) at 60~80℃ until the moisture content becomes 10~15% (v / w); and

[0048] (4) The dried fermented rice bran from step (3) above is fed into a pellet molding machine at 70~90℃ It may include a step of forming into pellets of a size of 2 to 8 mm, and

[0049] More specifically,

[0050] (1) A step of adding twice the amount of water (v / w) relative to the rice bran, sterilizing at 95°C for 15 minutes, and cooling;

[0051] (2) Bacillus licheniformis ( Bacillus licheniformis A step of preparing a fermented rice bran product by inoculating and mixing a strain culture solution, followed by solid-state fermentation at 30℃ for 48 hours;

[0052] (3) A step of drying the fermented rice bran product prepared in step (2) at 70°C until the moisture content becomes 12% (v / w); and

[0053] (4) The dried fermented rice bran from step (3) above is fed into a pellet molding machine at 70~90℃ It may include a step of forming pellets of size 2 to 8 mm.

[0055] The present invention will be described in detail below with reference to manufacturing examples and embodiments. However, the following manufacturing examples and embodiments are merely illustrative of the present invention, and the content of the present invention is not limited to the following manufacturing examples and embodiments.

[0057] Preparation Example 1. Fermented rice bran pellets

[0058] (1) Water was added in an amount equal to 2 times (v / w) of the selected rice bran, sterilized at 95°C for 15 minutes, and cooled to 30°C.

[0059] (2) 2.0×10 to the cooled rice bran of step (1) above 8 Bacillus licheniformis at a concentration of cfu / g ( Bacillus licheniformis A fermented rice bran product was prepared by inoculating 5% (w / w) of the KCTC1030 strain culture solution, mixing, and then fermenting on a solid basis at 30°C for 48 hours.

[0060] (3) The fermented rice bran product prepared in step (2) above was dried at 70°C until the moisture content became 12% (v / w).

[0061] (4) The dried fermented rice bran from step (3) above is fed into a pellet molding machine at 70~90℃ It was molded into pellets with a size of 2 to 8 mm.

[0063] Comparative Example 1. Rice bran pellets

[0064] (1) A rice bran mixture was prepared by adding twice the amount of water (v / w) relative to the rice bran to the selected rice bran, sterilized at 95°C for 15 minutes, and cooled to 30°C.

[0065] (2) The cooled rice bran mixture from step (1) above was dried at 70°C until the moisture content became 12% (v / w).

[0066] (3) The dried rice bran mixture from step (2) above is fed into a pellet molding machine at 70~90℃ It was molded into pellets with a size of 2 to 8 mm.

[0068] Comparative Example 2. Fermented rice bran pellets

[0069] Rice bran fermentation pellets are prepared by the method of Preparation Example 1, wherein in step (2) above, Bacillus licheniformis ( Bacillus licheniformis ) Instead of the KCTC 1030 strain, Bacillus subtilis ( Bacillus subtilis Rice bran fermentation pellets were prepared using the strain.

[0071] Comparative Example 3. Fermented rice bran pellets

[0072] (1) Water was added in an amount equal to 2 times (v / w) of the selected rice bran, sterilized at 121°C for 5 minutes, and cooled to 30°C.

[0073] (2) 2.0×10 to the cooled rice bran of step (1) above 8 cfu / g Bacillus licheniformis ( Bacillus licheniformisA fermented rice bran product was prepared by inoculating 5% (w / w) of the KCTC1030 strain culture solution, mixing, and then fermenting on a solid basis at 30°C for 36 hours.

[0074] (3) The fermented rice bran product prepared in step (2) above was dried at 50°C until the moisture content became 12% (v / w).

[0075] (4) The dried fermented rice bran from step (3) above was fed into a pellet molding machine and molded into pellets of size 2 to 8 mm at 45°C.

[0077] Comparative Example 4. Fermented rice bran pellets

[0078] (1) Water was added in an amount equal to 2 times (v / w) of the selected rice bran, sterilized at 80°C for 30 minutes, and cooled to 30°C.

[0079] (2) 2.0×10 to the cooled rice bran of step (1) above 8 cfu / g Bacillus licheniformis ( Bacillus licheniformis A fermented rice bran product was prepared by inoculating 5% (w / w) of the KCTC1030 strain culture solution, mixing, and then fermenting on a solid basis at 50°C for 72 hours.

[0080] (3) The fermented rice bran product prepared in step (2) above was dried at 85°C until the moisture content became 12% (v / w).

[0081] (4) The dried fermented rice bran from step (3) above is fed into a pellet molding machine at 110°C It was molded into pellets with a size of 2 to 8 mm.

[0083] Experimental method

[0084] 1) Measurement of moisture content

[0085] The moisture content was measured using a 105°C infrared moisture meter after weighing 1.5 to 2 g of a uniformly ground sample.

[0087] 2) Measurement of α-amylase activity

[0088] 0.1 mL of sample supernatant and 0.1 mL of phosphate buffer (pH 6.0) were mixed with 0.1 mL of 1% water-soluble starch and heated at 100°C for 5 minutes to inactivate the amylase in the sample, and the result was measured by the DNS (3,5-dinitrosalicle acid) method and used as a control. Then, 0.1 mL of 1% water-soluble starch, 0.1 mL of sample supernatant and 0.1 mL of phosphate buffer were mixed and reacted at 40°C for 15 minutes, followed by heating at 100°C for 5 minutes to inactivate the enzyme, and the sugar content was measured by the DNS method.

[0090] 3) pH measurement

[0091] It was measured using a pH meter (Metrohm 691, Swiss).

[0093] 4) Total bacterial count

[0094] 1 mL of the test solution and 1 mL of the 10-fold serial dilution were aseptically placed into at least two sterile Petri dishes, and approximately 15 mL of standard agar medium (medium 1) maintained at about 43–45°C was aseptically dispensed. The specimen and the medium were thoroughly mixed and solidified by quietly rotating and tilting the Petri dish from side to side, taking care not to adhere to the lid.

[0095] To suppress the occurrence of spreading colonies, 3 to 5 mL of standard agar medium was added and overlaid. The solidified Petri dishes were inverted and incubated at 35±1℃ for 48±2 hours (or 30±1℃ or 35±1℃ for 72±3 hours depending on the sample). For the count of colonies, plates with no spreading colonies and 15 to 300 colonies per plate were selected and counted.

[0097] 5) E. coli

[0098] Three or more diluted samples (10, 1, 0.1 or 1, 0.1, 0.01 or 0.1, 0.01, 0.001) were inoculated into five or three EC medium (medium 10) fermentation tubes, respectively, and then cultured at 44±1℃ for 24±2 hours.

[0099] However, when inoculating 10 mL, 2x concentration EC medium was used, and when it was necessary to inoculate 0.1 mL or less, 1 mL of each 10x diluted step solution was used. The sterility of the test procedure was confirmed by using the same diluted solution without the test solution added as a control solution.

[0100] For fermentation tubes that showed gas production, the corresponding EC fermentation tubes were inoculated into EMB medium and cultured at 35–37°C for 24 ± 2 hours. Then, typical colonies were inoculated onto plain agar medium (medium 8) or Tryptic Soy agar medium (medium 40) and cultured at 35–37°C for 24 ± 2 hours. Colonies cultured on plain agar medium or Tryptic Soy agar medium were taken and Gram stained to confirm Gram-negative, non-spore-forming bacilli. The number of E. coli in 1 mL or 1 g of the sample was calculated from the Most Probable Number table.

[0102] 6) Sensory evaluation

[0103] Sensory evaluation was conducted on researchers in the food and beverage industry, and to determine the panelists' preferences, three categories of preference—aroma, taste, and overall preference—were assessed. A 9-point scale was used for evaluation (1: strongly dislike, 2: very dislike, 3: dislike, 4: slightly dislike, 5: neither like nor dislike, 6: slightly like, 7: like, 8: very like, 9: extremely like), and after evaluating each sample, the panelists were instructed to rinse their mouths with purified water at room temperature before evaluating.

[0105] Example 1. Changes in pH and moisture content of rice bran according to fermentation time

[0106] Bacillus licheniformis in rice bran ( Bacillus licheniformis The results of comparing the pH and moisture content of the fermented rice bran according to the fermentation time after inoculating the strain culture solution are shown in Table 1 below. As a result, as the fermentation time of the rice bran increased, the pH and moisture content decreased, but no significant changes occurred and remained stable.

[0107] Changes in pH and moisture content of rice bran according to fermentation time Fermentation time pH Moisture content (%) 0 hours 7.02 84.6 12 hours 6.96 83.2 36 hours 6.95 80.5 48 hours 6.93 80.2 60 hours 6.72 80.4

[0109] Example 2. Change in bacterial count according to rice bran fermentation time

[0110] The results of comparing the changes in the number of bacteria in the fermented rice bran according to the fermentation time after inoculating rice bran with a culture of Bacillus licheniformis strain are shown in Table 2 below. As a result, the number of bacteria showed maximum activity at 36 hours of fermentation and showed high activity up to 48 hours of fermentation.

[0111] Changes in bacterial count according to rice bran fermentation time Fermentation time OD 0 hours 0.00 12 hours 1.90 36 hours 2.68 48 hours 2.25 60 hours 1.96

[0113] Example 3. Change in amylase activity according to the fermentation time of rice bran

[0114] The results of comparing the changes in amylase activity of fermented rice bran according to fermentation time after inoculating rice bran with a culture of Bacillus licheniformis strain are shown in Table 3 below. As a result, the α-amylase enzyme activity was highest at 48 hours of fermentation, and at 60 hours of fermentation, the activity decreased to less than half of that at 48 hours of fermentation.

[0115] Changes in amylase activity of rice bran according to fermentation time Fermentation time α-amylase activity (unit / mL) 0 hours ND 12 hours 680 36 hours 9,600 48 hours 18,840 60 hours 7,230

[0117] Example 4. Quality changes of fermented rice bran pellets during processing and storage

[0118] The results of comparing the quality changes of fermented rice bran pellets before and after processing into pellets are shown in Table 4 below. As a result, even after processing into pellets, the α-amylase activity did not show a significant change, and E. coli was not detected.

[0119] Changes in the quality of fermented rice bran pellets before and after processing into pellets item Before processing After processing α-amylase activity (unit / mL) 18,840 18,200 moisture(%) 12.4 10.3 General bacteria (cfu / g) 1,000 or less 700~1,000 E. coli ND ND

[0120] In addition, when fermented rice bran pellets were packaged and stored at normal room temperature and changes over time were observed every two months, overall enzyme activity and other factors remained stable, and general bacteria and E. coli were not a problem (Table 5).

[0121] Quality changes of fermented rice bran pellets during storage item Storage period (months) 2 4 6 8 α-amylase activity (unit / mL) 18,400 18,630 18,670 18,660 moisture(%) 12.2 12.2 11.2 11.6 General bacteria (cfu / g) 700~1,000 700~1,000 700~1,000 700~1,000 E. coli ND ND ND ND

[0123] Example 5. Sensory evaluation of fermented rice bran pellets

[0124] The results of the sensory evaluation of the fermented rice bran pellets of Preparation Example 1 and Comparative Examples are shown in Table 6 below. As a result, the unfermented rice bran pellet of Comparative Example 1 showed the lowest score in all categories, followed by the fermented rice bran pellet of Comparative Example 2. Among the fermented rice bran pellets, Preparation Example 1 showed the highest score in all categories, confirming that the rice bran pretreatment, strain type, fermentation, drying, and pelletization conditions of Preparation Example 1 were the most optimal.

[0125] Sensory evaluation of fermented rice bran pellets item incense taste Overall preference Preparation Example 1 7.6 7.4 7.4 Comparative Example 1 4.4 5.0 4.8 Comparative Example 2 5.2 5.6 5.4 Comparative Example 3 5.6 6.0 6.0 Comparative Example 4 5.8 6.4 6.2

Claims

Claim 1 (1) a step of adding 1 to 3 times (v / w) of water relative to the rice bran, sterilizing at 90 to 100°C for 10 to 20 minutes, and cooling; (2) Bacillus licheniformis ( Bacillus licheniformis ) strain A step of preparing a fermented rice bran product by inoculating and mixing a culture solution and then solid-state fermenting at 28–32°C for 40–56 hours; (3) a step of drying the fermented rice bran product prepared in step (2) at 60–80°C until the moisture content reaches 10–15% (v / w); and (4) feeding the dried fermented rice bran product from step (3) into a pellet molding machine at 70–90°C A method for manufacturing fermented rice bran pellets, characterized by including a step of molding into pellets of a size of 2 to 8 mm. Claim 2 delete Claim 3 delete Claim 4 In paragraph 1, the above Bacillus licheniformis ( Bacillus licheniformis The ) strain is Bacillus licheniformis( Bacillus licheniformis A method for manufacturing rice bran fermented pellets characterized by the KCTC1030 strain. Claim 5 Rice bran fermented pellets produced by the method of paragraph 1 or 4. Claim 6 (1) a step of adding 1 to 3 times (v / w) of water relative to the rice bran, sterilizing at 90 to 100°C for 10 to 20 minutes, and cooling; (2) Bacillus licheniformis ( Bacillus licheniformis ) strain A step of preparing a fermented rice bran product by inoculating and mixing a culture solution and then solid-state fermenting at 28–32°C for 40–56 hours; (3) a step of drying the fermented rice bran product prepared in step (2) at 60–80°C until the moisture content reaches 10–15% (v / w); and (4) feeding the dried fermented rice bran product from step (3) into a pellet molding machine at 70–90°C A method for enhancing the α-amylase activity and storage stability of fermented rice bran pellets, comprising the step of forming them into pellets of a size of 2 to 8 mm.

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