NL2029425B1

NL2029425B1 - Barley flour milling process for separating endosperm and bran based on combined grinding technology

Info

Publication number: NL2029425B1
Application number: NL2029425A
Authority: NL
Inventors: Wang Lili; Jin Nuo; Tong Litao; Fan Bei; Wang Fengzhong
Original assignee: Institute Of Food Science And Tech Chinese Academy Of Agricultural Sciences
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2023-05-16

Abstract

The present invention discloses a barley flour milling process for separating endosperm and bran based on combined grinding technology, including: removing impurities of raw barley to obtain pure barley, removing superficial bran of the pure barley, adding water to 14-3 5% moisture content in the pure barley, adding edible alkali accounting for 0.03-0.05% of raw barley weight, placing at 25-350C for 10-30 h, introducing steam to perform activity adjustment treatment of lipase and lipoxygenase, and grinding barley with a flour milling machine to obtain barley flour. The present invention can inactivate lipase and lipoxygenase in bran, thereby improving the stability of barley flour, ensuring the long-term storage of barley flour, avoiding adverse effects caused by frying treatment in the traditional flour milling process, and improving the quality of barley flour.

Description

BARLEY FLOUR MILLING PROCESS FOR SEPARATING ENDOSPERM AND

BRAN BASED ON COMBINED GRINDING TECHNOLOGY

TECHNICAL FIELD

The present invention relates to the field of grain processing. More particularly, the present invention relates to a barley flour milling process for separating endosperm and bran based on combined grinding technology.

BACKGROUND

Barley has the characteristics of high protein, high fiber, high vitamins, low fat and low sugar, wherein the average content of protein is 11.31%, which is higher than that of wheat, rice and corn. In particular, the content of 8 essential amino acids for the human body is higher than the above 3 kinds of grains. The starch mainly exists in the form of amylopectin, the content of soluble fiber and total fiber are higher than other cereal crops, and every 100 g of barley contains 1.8 mg of dietary fiber. Barley is also rich in B vitamins and a variety of inorganic elements that are beneficial to human health, such as calcium, phosphorus, iron, copper, zinc and trace element selenium, which have a positive effect on promoting healthy human growth.

At present, the main research and application directions of barley are concentrated on extraction and purification of its high value-added products: B-dextran, and the status of barley as an auxiliary material or a main raw material for a staple food product is not prominent. The barley flour milling process technology is the basis and prerequisite for the application of barley as a staple food product, which mainly includes two barley flour milling processes: one is a traditional flour milling process, and the other is an improved process combined with wheat flour milling. The traditional flour milling process mainly includes the steps of! removing impurities, performing frying treatment, and crushing barley seeds, wherein the crushing process includes mechanical crushing and stone crushing. The improved process combined with wheat flour milling adopts peeling, moisturizing, multiple-milling and screening to improve the flour extraction rate of barley flour.

In the traditional flour milling process, the role of the frying treatment is mainly to adjust the activity of lipase and lipoxygenase in barley. However, Enzymes have low water activity 1 in a low-water environment, and a long-term high-temperature treatment is required to achieve a better enzyme activity regulation effect. The long-term high-temperature treatment will not only affect the enzymes, but also affect other components in barley, which will ultimately affect the quality of products. Besides, after frying treatment, the moisture of barley will be further reduced. Although the flour extraction rate of the mechanical crushing is high, the starch damage is more serious by rapidly increasing temperature, and frying equipments are difficult to achieve precise control, most of which rely on experience so that it may lead to unstable product quality. Although the traditional stone crushing process can obtain barley flour with better storage quality, the stone crushing process mainly adopts fine control means such as the specific heat of raw material, low speed, sacrificing granularity to achieve relatively stable quality of barley flour during storage process, which has low production efficiency and unrealizable continuous production. Moreover, in the stone crushing process, endosperm parts that are easy to become powder and bran parts that are difficult to become powder are mixed for powder production. If the milling time is too short, the particle sizes of the bran parts are too larger, which affects product taste. If the milling time is too long, the endosperm parts are seriously damaged.

In the improved process combined with wheat flour milling, the enzyme activity is not adjusted before flour milling so that the lipase and lipoxygenase in the bran maintain high enzyme activity. Besides, the toughness of barley bran and that of wheat bran are significant differences. Even if the barley bran is subjected to moisturizing treatment before flour milling process, the barley bran will not form large pieces that are easy to separate during the flour milling process, and is partially mixed into the barley flour. The higher the extraction rate of flour, the more barley bran is mixed in. The bran that has not been subjected to adjusting enzyme activity will shorten the quality of barley flour during a storage process. In addition, the improved process adopts multiple milling processes to increase the extraction rate of barley flour, which needs longer process and more equipments, leads to discarding of the bran containing most of the functional substances, and cannot guarantee the long-term storage of barley flour.

SUMMARY

An object of the present invention is to provide a barley flour milling process for 2 separating endosperm and bran based on combined grinding technology, which can inactivate lipase and lipoxygenase in the barley bran, thereby improving the stability of barley flour, ensuring the long-term storage of barley flour, avoiding adverse effects caused by the frying treatment in the traditional flour milling process, and improving the quality of barley flour.

In order to achieve the above object, the present invention provides a barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of: removing impurities of raw barley to obtain pure barley, removing superficial bran of the pure barley, adding water to 14-35% moisture content in the pure barley, adding edible alkali accounting for 0.03-0.05% of a weight of the raw barley, placing at 25-35°C for 10-30 h, introducing steam with a humidity of 80-95% to perform activity adjustment treatment of lipase and lipoxygenase, wherein, when the steam is 80-100°C normal pressure steam, time for the activity adjustment treatment is 20-50 min, and when the steam is 120°C superheated steam, time for the activity adjustment treatment is 10-30s, and grinding barley with a flour milling machine to obtain barley flour; wherein a specific operation of the grinding barley with the flour milling machine to obtain barley flour includes: step one, grinding barley after activity adjustment treatment of lipase and lipoxygenase with the flour milling machine combined gear rollers and smooth rollers, screening with a square plansifter with an aperture of 80-150 mesh to obtain endosperm powder and bran with part of endosperm; step two, grinding the bran with part of endosperm obtained in the step one with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 60-130 mesh to obtain bran powder; step three, mixing the endosperm powder obtained in the step one and the bran powder obtained in the step two after being pretreated, according to a mass ratio of 7.5-5.5 : 4.5-2.5, and then performing vacuum packaging to obtain barley flour; wherein a specific operation of the step three includes: adding a mixture of purified water and white vinegar with a mass ratio of 5:1 into the bran powder, stirring, holding it for 1 30h, irradiating it with microwaves with a frequency of 300 MHz for 5 min and microwaves 3 with a frequency of 500 MHz for 3 min, repeating the above irradiating for 3 times, adding a mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil with a mass ratio of 1:3:2:2:1, stirring, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of 80 mesh, collecting filtrate, concentrating it, spray-drying it to obtain pretreated bran powder, and mixing the pretreated bran powder and the endosperm powder according to the above ratio; wherein, an additive amount of the mixture of purified water and white vinegar is 3 times a weight of the bran powder, an additive amount of the mixture of peppermint powder,

P-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder, and a preparation process of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil includes: weighing peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil according to a certain ratio, grinding the peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min.

Preferably, a specific operation of removing impurities includes screening raw barley with a vibrating screen, and removing stones with a specific-gravity stoner.

Preferably, removing superficial bran of the pure barley refers to removing an outer bran layer that accounts for 2-5% of the weight of the pure barley.

Preferably, a specific operation of removing superficial bran of the pure barley includes adding water accounting for 1-3% of the weight of the pure barley, holding it in an environment with a temperature of 20-35°C until 80-90% of the thickness of the bran of the pure barley is penetrated, and transporting it to a flour milling machine to grind off the superficial bran.

Preferably, the specific operation of removing superficial bran of the pure barley also includes spraying water when the pure barley is transported to the flour milling machine, and controlling a transporting distance so that 80-90% of the thickness of the bran of the pure barley is penetrated by water before entering the flour milling machine.

Preferably, in the step of adding water to 14-35% moisture content in the pure barley, 4 wherein water 1s mixed with cellulase accounting for 0.03-0.12% of a weight of water.

It needs to be stated that the barley described in the present invention includes hulled barley and unhulled barley, wherein the unhulled barley needs to be subjected to hulling process between removing impurities and removing superficial bran of the pure barley, and the hulling process is readily envisaged for the person skilled in the art, therefore, a specific operation of the hulling process are not described here.

The present invention includes at least the following advantages: (1) The flour milling process of the present invention adopts steam to perform activity adjustment treatment of lipase and lipoxygenase for barley, which can inactivate lipase and lipoxygenase in the barley bran, thereby improving the stability of barley flour, ensuring the long-term storage of barley flour, and avoiding adverse effects caused by the frying treatment in the traditional flour milling process. (2) In the flour milling process of the present invention, the outer bran layer that accounts for 2 to 5% of the weight of the pure barley is removed, so that harmful microorganisms, pesticide residues and other toxic and harmful substances attached to the bran of the barley can be removed, thereby ensuring the safety and health of the final barley flour, simultaneously shortening the time of water penetration and improving the production efficiency of the barley flour milling process. (3) In the flour milling process of the present invention, the bran powder is subjected to pretreatment before mixing with the endosperm powder, which can further improve the stability of the barley flour, thereby increasing the stability of the barley flour, prolonging the storage time of the barley flour, reducing the particle size of the bran flour, improving the taste of the barley flour, and obtaining a delicate and tasty taste. Because the bran of the barley is not easy to become powder, the particle size of the bran powder obtained by grinding with a stone mill are still large, which results in a poor taste of barley flour and is not conducive to widespread promotion. In the pretreatment process of the bran powder, the bran powder is soaked with the mixture of purified water and white vinegar, which can soften the bran powder. The irradiating processes with microwaves can increase the pore structure of the surface of the bran powder, and the grinding process with colloid mill can greatly reduce the size of the bran powder, make the bran powder more delicate, and completely inactivate the 5 lipase and lipoxygenase that may not be completely inactivated in the bran. The addition of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil can prevent the degeneration of the nutrients in the bran powder caused by the heat energy generated by the grinding with the colloid mill, and ensure the nutritional value and quality of the bran powder. Besides, peanut oil, olive oil and sunflower oil can also play a lubricating role to reduce the wear of the colloid mill. (4) The flour milling process of the present invention can prepare the barley flour with high safety, good stability, long storage time and good taste, and can guarantee the nutritional value and quality of barley flour. (5) In the flour milling process of the present invention, edible alkali accounting for 0.03-0.05% of raw barley weight is added before activity adjustment treatment of lipase and lipoxygenase, which greatly reduce the activity of lipase and lipoxygenase, and improve the stability of barley flour. (6) In the flour milling process of the present invention, in the step of adding water to 14-35% moisture content in the pure barley, water is mixed with cellulase accounting for 0.03-0.12% of the weight of water, which can prevent the subsequent activity adjustment treatment of lipase and lipoxygenase from causing gelatinization of barley, and is also more conducive to the entry of edible alkali into the cell wall and reducing the activity of lipase and lipoxygenase.

DETAILED DESCRIPTION

The present invention will now be described in further detail with reference to the accompanying drawings in order to enable person skilled in the art to practice with reference to the summary.

It should be noted that terms such as "having", "including" and "comprising" as used herein do not exclude presence or addition of one or more other elements or combinations thereof.

Embodiment 1

A barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of; screening raw barley with a vibrating screen, removing stones with a specific-gravity stoner to obtain pure barley, adding water that 6 accounts for 3% of the weight of the pure barley into the pure barley, holding it in an environment with a temperature of 30°C until 90% of the thickness of the bran of the pure barley is penetrated by controlling the holding time, transporting it to a flour milling machine to grind off the superficial bran (an outer bran layer that accounts for 3% of the weight of the pure barley), adding water to 14% moisture content in the pure barley, adding edible alkali accounting for 0.03% of the weight of the raw barley, holding it at 30°C for 20 h, introducing 100°C normal pressure steam with a humidity of 95% to perform activity adjustment treatment of lipase and lipoxygenase for 20 min, grinding barley after activity adjustment treatment of lipase and lipoxygenase with a flour milling machine combined gear rollers and smooth rollers, screening it with a square plansifter with an aperture of 150 mesh to obtain endosperm powder and bran with part of endosperm, grinding the bran with part of endosperm with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 130 mesh to obtain bran powder, adding a mixture of purified water and white vinegar with a mass ratio of 5:1 into the bran powder, wherein an additive amount of the mixture of purified water and white vinegar is 3 times the weight of the bran powder; stirring it, holding it for 1 h, irradiating it with microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min, repeating the above irradiating (microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min) for 3 times, weighing peppermint powder, B-cyclodextrin,

peanut oil, olive oil and sunflower oil according to a mass ratio of 1:3:2:2:1, grinding the peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing it to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min to obtain a mixture, wherein an additive amount of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder; adding the mixture into the bran powder, stirring it, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of 80 mesh, collecting filtrate, concentrating fit, spray-drying it to obtain pretreated bran powder, and mixing the pretreated bran powder and the endosperm powder according to a mass ratio of 7.5:2.5, and performing vacuum

7 packaging to obtain barley flour.

Embodiment 2

A barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of; screening raw barley with a vibrating screen, removing stones with a specific-gravity stoner to obtain pure barley, transporting the pure barley to a milling machine to grind off the superficial bran (an outer bran layer that accounts for 4% of the weight of the pure barley), spraying water when the pure barley is transported to the flour milling machine, controlling a transporting distance so that 90% of the thickness of the bran of the pure barley is penetrated by water before entering the flour milling machine, adding water to 16% moisture content in the pure barley, adding edible alkali accounting for 0.05% of the weight of the raw barley, holding it at 35°C for 20 h, introducing 90°C normal pressure steam with a humidity of 90% to perform activity adjustment treatment of lipase and lipoxygenase for 35 min, grinding barley after activity adjustment treatment of lipase and lipoxygenase with a flour milling machine combined gear rollers and smooth rollers, screening it with a square plansifter with an aperture of 130 mesh to obtain endosperm powder and bran with part of endosperm, grinding the bran with part of endosperm with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 120 mesh to obtain bran powder, adding a mixture of purified water and white vinegar with a mass ratio of 5:1 into the bran powder, wherein an additive amount of the mixture of purified water and white vinegar is 3 times the weight of the bran powder; stirring it, holding it for 1 h, irradiating it with microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min, repeating the above irradiating (microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min) for 3 times, weighing peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil according to a mass ratio of 1:3:2:2:1, grinding the peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing it to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min to obtain a mixture, wherein an additive amount of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder; adding the mixture into the bran 8 powder, stirring it, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of 80 mesh, collecting filtrate, concentrating it, spray-drying it to obtain pretreated bran powder, and mixing the pretreated bran powder and the endosperm powder according to a mass ratio of 7:3, and performing vacuum packaging to obtain barley flour.

Embodiment 3

A barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of; screening raw barley with a vibrating screen, removing stones with a specific-gravity stoner to obtain pure barley, adding water that accounts for 2% of the weight of the pure barley into the pure barley, holding it in an environment with a temperature of 20°C until 85% of the thickness of the bran of the pure barley is penetrated by controlling the holding time, transporting it to a flour milling machine to grind off the superficial bran (an outer bran layer that accounts for 5% of the weight of the pure barley), adding water to 18% moisture content in the pure barley, adding edible alkali accounting for 0.04% of the weight of the raw barley, holding it at 25°C for 10 h, introducing 120°C superheated steam with a humidity of 95% to perform activity adjustment treatment of lipase and lipoxygenase for 10s, grinding barley after activity adjustment treatment of lipase and lipoxygenase with a flour milling machine combined gear rollers and smooth rollers, screening it with a square plansifter with an aperture of 100 mesh to obtain endosperm powder and bran with part of endosperm, grinding the bran with part of endosperm with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 100 mesh to obtain bran powder, adding a mixture of purified water and white vinegar with a mass ratio of 5:1 into the bran powder, wherein an additive amount of the mixture of purified water and white vinegar is 3 times the weight of the bran powder; stirring it, holding it for 1 h, irradiating it with microwaves with a frequency of 300

MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min, repeating the above irradiating (microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min) for 3 times, weighing peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil according to a mass ratio of 1:3:2:2:1, grinding the 9 peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing it to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min to obtain a mixture, wherein an additive amount of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder; adding the mixture into the bran powder, stirring it, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of 80 mesh, collecting filtrate, concentrating it, spray-drying it to obtain pretreated bran powder, and mixing the pretreated bran powder and the endosperm powder according to a mass ratio of 6.5 : 3.5, and performing vacuum packaging to obtain barley flour.

Embodiment 4

A barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of; screening raw barley with a vibrating screen, removing stones with a specific-gravity stoner to obtain pure barley, adding water that accounts for 1% of the weight of the pure barley into the pure barley, holding it in an environment with a temperature of 35°C until 80% of the thickness of the bran of the pure barley is penetrated by controlling the holding time, transporting it to a flour milling machine to grind off the superficial bran (an outer bran layer that accounts for 2% of the weight of the pure barley), adding water to 25% moisture content in the pure barley, adding edible alkali accounting for 0.03% of the weight of the raw barley, holding it at 35°C for 30 h, introducing 80°C normal pressure steam with a humidity of 80% to perform activity adjustment treatment of lipase and lipoxygenase for 50 min, grinding barley after activity adjustment treatment of lipase and lipoxygenase with a flour milling machine combined gear rollers and smooth rollers, screening it with a square plansifter with an aperture of 90 mesh to obtain endosperm powder and bran with part of endosperm, grinding the bran with part of endosperm with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 80 mesh to obtain bran powder, adding a mixture of purified water and white vinegar with a mass ratio of 5:1 into the bran powder, wherein an additive amount of the mixture of purified water and white vinegar is 3 times the weight of the bran 10 powder; stirring it, holding it for 1 h, irradiating it with microwaves with a frequency of 300

MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min, repeating the above irradiating (microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min) for 3 times, weighing peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil according to a mass ratio of 1:3:2:2:1, grinding the peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing it to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min to obtain a mixture, wherein an additive amount of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder; adding the mixture into the bran powder, stirring, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of 80 mesh, collecting filtrate, concentrating it, spray-drying it to obtain pretreated bran powder, and mixing the pretreated bran powder and the endosperm powder according to a mass ratio of 6:4, and performing vacuum packaging to obtain barley flour.

Embodiment 5

A barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of; screening raw barley with a vibrating screen, removing stones with a specific-gravity stoner to obtain pure barley, transporting the pure barley to a milling machine to grind off the superficial bran (an outer bran layer that accounts for 4% of the weight of the pure barley), spraying water when the pure barley is transported to the flour milling machine, controlling a transporting distance so that 85% of the thickness of the bran of the pure barley is penetrated by water before entering the flour milling machine, adding water to 35% moisture content in the pure barley, adding edible alkali accounting for 0.05% of the weight of the raw barley, holding it at 30°C for 20 h, introducing 120°C superheated steam with a humidity of 90% to perform activity adjustment treatment of lipase and lipoxygenase for 20 s, grinding barley after activity adjustment treatment of lipase and lipoxygenase with a flour milling machine combined gear rollers and smooth rollers, screening it with a square plansifter with an aperture of 80 mesh to obtain 11 endosperm powder and bran with part of endosperm, grinding the bran with part of endosperm with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 60 mesh to obtain bran powder, adding a mixture of purified water and white vinegar with a mass ratio of 5:1 into the bran powder, wherein an additive amount of the mixture of purified water and white vinegar is 3 times the weight of the bran powder; stirring it, holding it for 1 h, irradiating it with microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min, repeating the above irradiating (microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min) for 3 times, weighing peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil according to a mass ratio of 1:3:2:2:1, grinding the peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing it to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min to obtain a mixture, wherein an additive amount of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder; adding the mixture into the bran powder, stirring, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of 80 mesh, collecting filtrate, concentrating, spray-drying it to obtain pretreated bran powder, and mixing the pretreated bran powder and the endosperm powder according to a mass ratio of 5.5 : 4.5, and performing vacuum packaging to obtain barley flour.

Embodiment 6

A barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of; screening raw barley with a vibrating screen, removing stones with a specific-gravity stoner to obtain pure barley, transporting the pure barley to a milling machine to grind off the superficial bran (an outer bran layer that accounts for 2% of the weight of the pure barley), spraying water when the pure barley is transported to the flour milling machine, controlling a transporting distance so that 80% of the thickness of the bran of the pure barley is penetrated by water before entering the flour milling machine, adding water to 14% moisture content in the pure barley, adding edible 12 alkali accounting for 0.04% of the weight of the raw barley, holding it at 35°C for 30 h, introducing 120°C superheated steam with a humidity of 80% to perform activity adjustment treatment of lipase and lipoxygenase for 30 s, grinding barley after activity adjustment treatment of lipase and lipoxygenase with a flour milling machine combined gear rollers and smooth rollers, screening it with a square plansifter with an aperture of 80 mesh to obtain endosperm powder and bran with part of endosperm, grinding the bran with part of endosperm with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 60 mesh to obtain bran powder, adding a mixture of purified water and white vinegar with a mass ratio of 5:1 into the bran powder, wherein an additive amount of the mixture of purified water and white vinegar is 3 times the weight of the bran powder; stirring it, holding it for 1 h, irradiating it with microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min, repeating the above irradiating (microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min) for 3 times, weighing peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil according to a mass ratio of 1:3:2:2:1, grinding the peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing it to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min to obtain a mixture, wherein an additive amount of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder; adding the mixture into the bran powder, stirring, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of 80 mesh, collecting filtrate, concentrating fit, spray-drying it to obtain pretreated bran powder, and mixing the pretreated bran powder and the endosperm powder according to a mass ratio of 6 : 4, and performing vacuum packaging to obtain barley flour.

Embodiment 7

A barley flour milling process for separating endosperm and bran based on combined grinding technology, including the following steps of; screening raw barley with a vibrating screen, removing stones with a specific-gravity stoner to obtain pure barley, transporting the 13 pure barley to a milling machine to grind off the superficial bran (an outer bran layer that accounts for 2% of the weight of the pure barley), spraying water when the pure barley is transported to the flour milling machine, controlling a transporting distance so that 80% of the thickness of the bran of the pure barley is penetrated by water before entering the flour milling machine, adding water containing cellulase accounting for 0.03% of water weight to 35% moisture content in the pure barley, adding edible alkali accounting for 0.04% of the weight of the raw barley, holding it at 35°C for 30 h, introducing 120°C superheated steam with a humidity of 80% to perform activity adjustment treatment of lipase and lipoxygenase for 30 s, grinding barley after activity adjustment treatment of lipase and lipoxygenase with a flour milling machine combined gear rollers and smooth rollers, screening it with a square plansifter with an aperture of 80 mesh to obtain endosperm powder and bran with part of endosperm, grinding the bran with part of endosperm with a stone flour milling machine with high specific heat capacity, screening it with a square plansifter with an aperture of 60 mesh to obtain bran powder, adding a mixture of purified water and white vinegar with a mass ratio of

5:1 into the bran powder, wherein an additive amount of the mixture of purified water and white vinegar is 3 times the weight of the bran powder; stirring it, holding it for 1 h, irradiating it with microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min, repeating the above irradiating (microwaves with a frequency of 300 MHz for 5 min and microwaves with a frequency of 500 MHz for 3 min) for

3 times, weighing peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil according to a mass ratio of 1:3:2:2:1, grinding the peppermint powder and B-cyclodextrin, screening it with 200 mesh sieve, mixing it to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder into the mixed oil at a rate of 2 g/min to obtain a mixture, wherein an additive amount of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder; adding the mixture into the bran powder, stirring, treating it with 600 MHz ultrasonic in a 20°C water bath for 30 min, grinding it with a colloid mill for 2 h under the protection of nitrogen gas, performing suction filtration with a filter cloth with a pore size of

80 mesh, collecting filtrate, concentrating it, spray-drying it to obtain pretreated bran powder,

and mixing the pretreated bran powder and the endosperm powder according to a mass ratio

14 of 6 : 4, and performing vacuum packaging to obtain barley flour.

Comparative example 1

A barley flour milling process for separating endosperm and bran based on combined grinding technology, whose process steps are the same as that in Embodiment 1, and the difference is that adding water to 5% moisture content in the pure barley before performing activity adjustment treatment of lipase and lipoxygenase.

Comparative example 2

A barley flour milling process for separating endosperm and bran based on combined grinding technology, whose process steps are the same as that in Embodiment 1, and the difference is that the step of adding edible alkali accounting for 0.03% of the weight of the raw barley is not included.

Comparative example 3

A barley flour milling process for separating endosperm and bran based on combined grinding technology, whose process steps are the same as that in Embodiment 1, and the difference is that the step of performing activity adjustment treatment of lipase and lipoxygenase is not included.

A method for evaluating the stability of barley flour includes: selecting the pure barley after activity adjustment treatment of lipase and lipoxygenase (in the Comparative Example 2, selecting the pure barley before grinding barley with a flour milling machine combined gear rollers and smooth rollers), determining the activity of lipase and lipoxygenase, and counting the results.

A method for evaluating the taste of barley flour includes: qualitatively evaluating the particle size of barley flour, simultaneously tasting the barley flour, performing a qualitative evaluation of the taste of barley flour, and counting the results.

After counting, the stability and taste results of barley flour prepared in Embodiments 1-7, Comparative Examples 1-3 and barley flour prepared by the traditional frying method are as follows: 15

Table 1

Lipase activity | Lipoxygenase (mg/g) activity (qualitative)

Embodiment 1 Not detected very fine powder particles, excellent taste

Embodiment 2 Not detected very fine powder particles, excellent taste

Embodiment 3 Not detected very fine powder particles, excellent taste

Embodiment 4 0.37+0. 14 very fine powder particles, excellent taste

Embodiment 5 Not detected very fine powder particles, excellent taste

Embodiment 6 0.25+0.07 very fine powder particles, excellent taste

Embodiment 7 Not detected very fine powder particles, excellent taste

Comparative 3.53+0.06 + finer powder particles,

Example 1 better taste

Comparative 5.8640.15 + finer powder particles,

Example 2 better taste

Comparative 16.23+0.11 + rough powder particles,

Example 3 poor taste traditional frying 7.63+0.13 + fine powder particles, good taste

Note: “+” indicates that lipoxygenase is positive and active; “--” indicates that lipoxygenase 16 is negative and inactive

It can be seen from the above Table 1 that the activity of lipase is not detected in the barley of Embodiments 1-7 or the activity of lipase is very low, which do not affect the stability of the barley flour. Besides, the activity of lipoxygenase is negative, which shows that the barley flour prepared by Embodiments 1-7 has good stability and is better than barley flour prepared by traditional frying method. In addition, the barley flour prepared by

Embodiments 1-7 has very fine powder particles and excellent taste, which is better than that of barley flour prepared by traditional frying method; wherein Embodiment 7 is the best

Embodiment.

Compared Comparative Example 1 with Embodiment 1, the barley flour milling process for separating endosperm and bran based on combined grinding technology in Comparative

Example 1 is the same as that in Embodiment 1, and the difference is that adding water to 5% moisture content in the pure barley before performing activity adjustment treatment of lipase and lipoxygenase. It can be seen from Table 1 that the activity of lipase in barley of

Comparative Example 1 is higher than that of Embodiment 1, while the activity of lipoxygenase is positive, which indicate that the stability of the barley flour prepared in

Comparative Example 1 is worse than that of the Embodiment 1. Besides, the taste of the barley flour prepared in Comparative Example 1 is poor, and this is mainly because the water content of the pure barley is too low, which causes that bran and endosperm are difficult to separate. During grinding processes, a large number of rough bran are mixed into the endosperm powder during grinding barley with a flour milling machine combined gear rollers and smooth rollers, which results in large particle size and poor taste in the final barley flour.

At the same time, the low water content of the pure barley will also result in less water penetration in the bran, which is not conducive to the subsequent activity adjustment treatment of lipase and lipoxygenase, thereby decreasing the stability of the barley flour.

However, when the water content of the pure barley is too high, powder is easy to stick during grinding process, which will greatly reduce the extraction rate of flour. Therefore, the optimum range of the water content of the pure barley is 14-35%. Besides, the barley flour prepared by Embodiments 1-6 has very fine powder particles and excellent taste, and this is mainly because the particle size is smaller after the bran powder is subjected to pretreatment. 17

The bran powder is soaked with the mixture of purified water and white vinegar, which can soften the bran powder. The irradiating process with microwaves can increase the pore structure of the surface of the bran powder. The grinding process with a colloid mill can greatly reduce the size of the bran powder, make the bran powder more delicate, and completely inactivate the lipase and lipoxygenase that may not be completely inactivated in the bran. The addition of the mixture of peppermint powder, B-cyclodextrin, peanut oil, olive oil and sunflower oil can prevent the degeneration of the nutrients in the bran powder caused by the heat energy generated by the grinding with the colloid mill, and ensure the nutritional value and quality of the bran powder. Besides, peanut oil, olive oil and sunflower oil can also play a lubricating role to reduce the wear of the colloid mill. In the Embodiment 7, water mixed with cellulase is used to adjust the water content of the pure barley so that obtained barley powder has very fine powder particles and excellent taste, which can prevent the subsequent activity adjustment treatment of lipase and lipoxygenase from causing gelatinization of barley, and is also more conducive to the entry of edible alkali into the cell wall and reducing the activity of lipase and lipoxygenase more significantly, greatly improving the stability and taste of barley flour.

Compared Comparative Example 2 with Embodiment 1, the barley flour milling process for separating endosperm and bran based on combined grinding technology in Comparative

Example 2 is the same as that in Embodiment 1, and the difference is that the step of adding edible alkali accounting for 0.03% of the weight of the raw barley is not included. It can be seen from Table 1 that the activity of lipase in barley of Comparative Example 2 is very high, while the activity of lipoxygenase is positive, which indicate that the stability of the barley flour prepared in Comparative Example 2 is significantly lower than that of the Embodiment 1 and there are not large effects on the taste. This is mainly because that edible alkali can promote the inactivation of lipase and lipoxygenase, thereby avoiding deterioration of the barley flour during a long-term storage and maintaining the long-term stability.

Compared Comparative Example 3 with Embodiment 1, the barley flour milling process for separating endosperm and bran based on combined grinding technology in Comparative

Example 3 is the same as that in Embodiment 1, and the difference is that the step of performing activity adjustment treatment of lipase and lipoxygenase is not included. It can be 18 seen from Table 1 that the activity of lipase in barley of Comparative Example 3 is very high, while the activity of lipoxygenase is positive, which indicate that the stability of the barley flour prepared in Comparative Example 3 is significantly lower than that of the Embodiment 1 and there are not large effects on the taste. This is mainly because that activity adjustment treatment of lipase and lipoxygenase inactivate a large amount of lipase and lipoxygenase in bran of barley, thereby avoiding deterioration of the barley flour during a long-term storage and maintaining the long-term stability.

Although the embodiments of the present invention have been disclosed above, they are not limited to the applications previously mentioned in the specification and embodiments, and can be applied in various fields suitable for the present invention. For ordinary skilled person in the field, other various changed model, formula and parameter may be easily achieved without creative work according to instruction of the present invention, changed, modified and replaced embodiments without departing the general concept defined by the claims and their equivalent are still included in the present invention. The present invention is not limited to particular details and illustrations shown and described herein. 19

Claims

CONCLUSIONS

1. Barley flour milling process for separating endosperm and bran based on combined milling technology, comprising the following steps: removing impurities from raw barley to obtain pure barley, removing superficial bran from the pure barley, adding water to 14 to 35% moisture content in the pure barley, adding edible alkali which is 0.03 to 0.05% by weight of the raw barley, placing at 25 to 35°C for 10 to 30 hours, inserting steam with a humidity of 80 to 95% to carry out the activity adjustment treatment of lipase and lipoxygenase, where when the steam is 80 to 100°C normal pressure steam, the time for the activity adjustment treatment is 20 to 50 minutes, and when the steam is 120° C is superheated steam, the time for the activity adjustment treatment is 10 to 30s, and milling barley with a flour milling machine to obtain barley flour; wherein a specific operation of milling barley with the flour crusher to obtain barley flour includes: - step one: milling barley after the activity adjustment treatment of lipase and lipoxygenase with the flour crusher with combined gear and smoothing rollers, and sieving with a square planifter with an opening of 80 to 150 mesh to obtain endosperm powder and bran with part of the endosperm; - step two: grinding the bran with part of the endosperm obtained in step one with a high specific heat capacity stone flour crusher, and sieving with a square planifter with an opening of 60 to 130 mesh to obtain bran powder; - step three: mixing the endosperm powder obtained in step one and the bran powder obtained in step two after pre-treatment, according to a mass ratio of 7.5 to 5.5 : 4.5 to 2.5, and then performing vacuum packaging to obtain barley flour; wherein a specific operation of step three comprises: adding a mixture of purified water and white vinegar at a mass ratio of 5:1 to the bran powder, stirring, holding for 1 hour, irradiating with microwaves at a frequency of 300 MHz for 5 minutes and microwaves with a frequency of 500 MHz for 3 minutes, repeating the above irradiation for 3 times, adding a mixture of peppermint powder, β-cyclodextrin, peanut oil, olive oil and sunflower oil with a mass ratio of 1 : 3 : 2:2:1, the stirring, the treatment with 600MHz ultrasonic in a water bath at 20°C for 30 minutes, the grinding with a colloid mill for 2 hours under nitrogen gas protection, performing suction filtration with a pore size filter cloth of 80 mesh, collecting filtrate, concentrating, spray-drying to obtain pre-treated bran powder, and mixing the pre-treated bran powder and endosperm powder according to the above ratio; wherein an added amount of the mixture of purified water and white vinegar is 3 times the weight of the bran powder 1s, an added amount of the mixture of peppermint powder, β-cyclodextrin, peanut oil, olive oil and sunflower oil is equal to the weight of the bran powder, and a preparation method of the mixture of peppermint powder, β-cyclodextrin, peanut oil, olive oil and sunflower oil includes: weighing peppermint powder, β-cyclodextrin, peanut oil, olive oil and sunflower oil according to a certain ratio, grinding the peppermint powder and β-cyclodextrin, sieving with 200 mesh sieve, mixing to obtain mixed powder, mixing peanut oil, olive oil and sunflower oil to obtain mixed oil, and adding the mixed powder to the mixed oil at a rate of 2 g/min.

The barley flour milling method for separating endosperm and bran based on combined milling technology according to claim 1, characterized in that a specific impurity removal operation comprises: sieving the raw barley with a vibrating sieve, and removing stones with a specific gravity stone removal machine.

A barley flour milling method for separating endosperm and bran based on combined milling technology according to claim 1, characterized in that the removal of superficial bran from the pure barley refers to the removal of an outer bran layer containing 2 to 5% of a weight of the pure barley. 21

A barley flour milling method for separating endosperm and bran based on combined milling technology according to claim 1, characterized in that a specific operation of removing superficial bran from the pure barley comprises: adding water containing 1 to 3% of a weight of the pure barley, keeping it in an environment with a temperature of 20 to 35°C until 80 to 90% of a thickness of the bran of the pure barley has penetrated, and transporting it to a flour mill to remove the superficial bran to grind..

The barley meal milling method for separating endosperm and bran based on combined milling technology according to claim 1, characterized in that the specific operation of removing superficial bran from the pure barley also includes: spraying water when the pure barley is sent to the milling machine is conveyed, and arranging a conveyance distance so that 80 to 90% of a thickness of the bran of the pure barley is penetrated by water before entering the flour milling machine.

The barley flour milling method for separating endosperm and bran based on combined milling technology according to claim 1, characterized in that in the step of adding water to a moisture content of 14 to 35% in the pure barley, the added water is mixed with cellulase comprising 0.03 to 0.12% by weight of the water. 22