Preparation method of highland barley fried malt with high antioxidant activity

Abstract

The invention discloses a preparation method of fried malt with highland barley for improving antioxidant activity, which comprises the following steps: spreading highland barley seeds soaked in water on filter paper, and culturing in an incubator; spraying water at set intervals to promote germination of the highland barley seeds; placing the germinated highland barley malt in a closed container, and replacing air with nitrogen to a low-oxygen environment; adopting a two-step drying method until the highland barley malt is completely dried; putting the dried highland barley malt into a stir-frying container, heating with slow fire, continuously turning over during heating, stir-frying, and cooling in a dryer; the roasted malt finished product which is high in germination rate, proper in bud length, low in malt shedding rate and high in antioxidant activity can be obtained, and the roasted malt finished product can be used for development of digestion-aiding health-care food with highland barley as a raw material.

Description

Technical Field

[0001] The present invention relates to the technical field of malt manufacturing, and specifically, to a method for preparing highland barley fried malt with improved antioxidant activity. Background Art

[0002] Fried malt is one of the commonly used traditional Chinese medicines for invigorating the spleen and promoting digestion in clinical practice, and is also recorded to have the effects of promoting lactation, lactation regression and soothing the liver. The earliest record of frying malt until charred was in "Harm and Benefit of Materia Medica" by Ling Huan in the Qing Dynasty, and there are few recorded documents. The extensive application of modern fried malt may be influenced by the theory of "charred fragrance for invigorating the spleen". In "Origin of Medicine", it is recorded that malt "tonifies the deficiency of the spleen and stomach, widens the intestines and stomach, pound it into fine powder, fry it until yellow, and use the powder", which means that taking fried malt is beneficial for tonifying the spleen and stomach and can also relieve the digestion-promoting effect caused by long-term use. Although the 2020 edition of the "Chinese Pharmacopoeia" has established clear sensory judgment standards for the appearance characteristics (such as color and smell) and traditional frying processes (such as firepower and time) of fried malt and charred malt, this experience-based quality control system has significant defects: First, relying solely on appearance characteristics (such as charred brown surface or charred aroma) lacks objective quantitative indicators and is easily affected by subjective judgment; second, the correlation standard between germination and processing degree has not been established, resulting in the disconnection between process parameters (such as temperature and time) and the pharmacodynamic substance basis, and thus it is impossible to ensure batch consistency. This experience-oriented quality control mode is difficult to meet the requirements of modern functional food research and development for standardization. From the perspective of modern pharmacology, fried malt is not only closely related to the activity of digestive enzymes, but its antioxidant activity has also gradually attracted attention. During the germination process of malt, functional components such as phenols, flavonoids and γ-aminobutyric acid (GABA) accumulate significantly, and these substances all have free radical scavenging and antioxidant effects. However, subsequent high-temperature frying is likely to cause the degradation or oxidation of some active substances, reducing the final antioxidant capacity.

[0003] Highland barley is a variety of the wheat tribe in the Gramineae family according to plant taxonomy. In addition, the inner and outer glumes of highland barley are separated from the caryopsis at harvest, and it is also known as hull-less barley or naked barley. Highland barley is a very important high-altitude food crop, with characteristics such as early maturity, cold tolerance, stable yield and strong adaptability. Compared with other cereal crops, highland barley contains β-glucan, arabinoxylan and polyphenols, and thus has higher antioxidant, anti-cancer and antibacterial properties. Regular intake of whole highland barley flour can reduce the risk of chronic diseases such as diabetes, colon cancer, hyperlipidemia, hypertension and gallstones. However, there has been no research on using highland barley as a raw material and preparing fried malt through micro-oxygen environment drying pretreatment to improve its antioxidant activity. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a scientific quality control method for preparing standard-compliant roasted barley malt, and to offer a method for preparing roasted barley malt with enhanced antioxidant activity. This invention is the first to use barley seeds as raw material to prepare roasted malt, which is economical and environmentally friendly, increasing the economic value of barley. This invention innovatively optimizes the integrated germination-roasting process of roasted barley malt. By precisely controlling germination conditions, roasting parameters, and micro-oxygen environment regulation, it improves the germination rate, reduces the malt shedding rate, and increases the proportion of 4-6 mm malt, providing reliable technical support for the industrial production of functional malt foods. By adjusting the germination environment and increasing the germination rate, it significantly enhances amylase activity, promotes the efficient conversion of endosperm starch into soluble sugars, and provides richer flavor precursors for subsequent roasting. Simultaneously, the use of temperature-controlled roasting technology results in a golden-brown, crispy outer skin and a light yellow, loose interior, avoiding the scorching or undercooked core problems common in traditional processes, and ensuring a rich aroma. The active ingredients (such as oligosaccharides and polyphenols) retained after roasting work synergistically with Maillard reaction products, maintaining the traditional "spleen and stomach tonifying" effects while significantly reducing the risk of excessive digestion (such as bloating and diarrhea) caused by long-term use. Furthermore, combining traditional germination and roasting processes with modern micro-oxygen environment control not only helps establish an objective and controllable quality evaluation index system, including germination rate, malt shedding rate, and the proportion of 4-6mm malt sprouts, but also improves batch consistency while further enhancing the antioxidant activity of roasted malt.

[0005] The objective of this invention is achieved through the following solution: This invention provides a method for preparing roasted barley malt with high antioxidant activity, the method comprising the following steps: S1. Sprinkle the soaked barley seeds onto filter paper and incubate them in an incubator; S2. Spray water periodically to encourage barley seeds to germinate; S3. Place the germinated barley malt in a sealed container and replace the air with nitrogen to create a low-oxygen environment. S4. Use a two-step drying method until the barley malt is completely dried; S5. Place the dried barley malt into a roasting container and heat over a low flame, turning it over frequently. After roasting, let it cool in an environment of 18-25℃ and 15%-20% relative humidity.

[0006] As one implementation scheme, step S5 also includes the step of pre-cooling the cooled roasted barley malt at a low temperature, then vacuum freeze-drying it, grinding it into powder, and collecting it to obtain freeze-dried roasted malt powder. This freeze-dried roasted malt powder needs to be stored at a low temperature.

[0007] As one implementation, the low-temperature precooling is performed at a temperature of -82 to -78°C for 45 to 60 minutes. The vacuum freeze-drying is performed at a freezing temperature of -45 to -35°C for 36 to 48 hours.

[0008] As one implementation scheme, in step S5, the frying temperature corresponding to the gentle heating is 210~250℃, and the frying time is 5~15 minutes. During this time, the malt is turned over frequently, and the malt is manually turned to prevent the roots from tangling.

[0009] As one implementation scheme, step S4, the two-step drying method includes: drying barley malt at 50-65°C for 2-3 hours, reducing the moisture content of the barley malt from 42-46% (w / w) to 5-10% (w / w); then slowly raising the temperature to 75-85°C, so that the final moisture content of the barley malt is 3-4% (w / w). The germination time of the grain affects the ratio of starch to enzymes, and each step of the process must be treated at the optimal time to obtain the highest quality malt. If the barley is soaked for too long, the result is premature germination, complete enzymatic decomposition of the starchy endosperm and its contents, and low protein levels.

[0010] As one implementation scheme, in step S3, the oxygen concentration in the low-oxygen environment is <5%, and it is maintained for 1 to 4 hours before proceeding to the two-step drying process in step S4.

[0011] As one implementation method, in step S2, 2-7 mL of distilled water is sprayed every 10-15 hours to promote malt germination. After the basal radicle has sprouted young shoots and fibrous roots, the malt is collected and manually mixed to prevent root entanglement.

[0012] As one implementation scheme, in step S1, the germination temperature corresponding to the cultivation is 20~28℃, the relative humidity required for germination is 85~95%, and the germination time is 36~48h.

[0013] This invention selects highland barley as the raw material for preparing roasted malt. In one embodiment, in step S1, plump highland barley seeds free from mold and pests are selected and soaked in distilled water. The soaking time is 5-7 hours.

[0014] The roasted barley malt obtained by the aforementioned method falls within the scope of protection of this invention. In the roasted barley malt prepared by the method of this invention, the proportion of buds with a length of 4-6 mm is greater than 20%.

[0015] The aforementioned use of roasted barley malt in the preparation of (functional) foods or health products also falls within the scope of protection of this invention.

[0016] During malt germination, functional components such as phenols, flavonoids, and γ-aminobutyric acid (GABA) accumulate significantly, all of which possess free radical scavenging and antioxidant properties. However, subsequent high-temperature roasting can easily lead to the degradation or oxidation of some active substances, reducing their final antioxidant capacity. Against this backdrop, the micro-oxygen environment pre-treatment introduced in this invention offers potential advantages: a micro-oxygen or nitrogen-rich environment can reduce the activity of reactive oxygen species (ROS) and oxidases (such as polyphenol oxidase, PPO), thereby delaying the oxidative browning of polyphenols and flavonoids and reducing the loss of active components such as vitamin C and GABA. Simultaneously, mild hypoxia may also induce germ cells to produce certain levels of antioxidant enzymes (such as superoxide dismutase SOD, peroxidase POD, and catalase CAT), further enhancing the malt's endogenous antioxidant defense system. This not only improves the stability and sensory quality of roasted malt but also enhances its functional value.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention can obtain roasted barley malt that meets the requirements of the pharmacopoeia. The raw material used is the barley variety "Dulihuang", which is economical and environmentally friendly, and improves the economic value of barley. (2) The method of the present invention is simple and easy to implement, with high production efficiency and low operating cost; it has low technical requirements for enterprises and can be widely promoted. (3) This invention controls key factors affecting germination rate and sprout length, such as moisture, temperature and germination time, and establishes an optimized process for roasted barley malt to produce roasted malt that meets the definition of the Pharmacopoeia of the People's Republic of China 2020 edition. It is spindle-shaped, with young sprouts and fibrous roots growing from the radicle at the base. The young sprouts are long lanceolate strips about 5 mm long, with several fibrous roots that are slender and curved. The surface is brownish-yellow with occasional scorch spots and a strong aroma. It has potential application value in the comprehensive utilization and production of barley. (4) This invention combines traditional germination and roasting processes with modern micro-oxygen environment regulation, which not only helps to establish an objective and controllable quality evaluation index system, including germination rate (reflecting the degree of metabolic activation), malt shedding rate (indicating the integrity of endosperm structure) and the proportion of 4-6mm malt sprout length (determining the uniformity of the final product), but also enhances the antioxidant capacity of roasted malt while improving batch consistency, providing new ideas for its application in functional food and modern research of traditional Chinese medicine. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 The germination rate of barley seeds; Figure 2 The shedding rate of barley malt; Figure 3 This refers to the proportion of barley sprouts with a length of 4-6 mm.

[0019] Figure 4 This is a graph showing the relative DPPH clearance value (RDSC). Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0021] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0022] The following are the methods used to determine the germination rate and sprout length of the barley sprouts: After the barley germinated, the sprout length was measured using vernier calipers, with a minimum graduation of 0.02 mm. 100 seeds were taken from each treatment. The germination rate (%) was calculated using the following formula: Germination rate (%) = Number of germinated barley seeds (grains) / Total number of barley seeds (grains) x 100%.

[0023] The determination method for DPPH free radical scavenging ability is based on the method provided in patent ZL202311855755.5. The DPPH free radical scavenging rate is determined using a DPPH free radical scavenging experiment. A 0.1 mol / L DPPH solution is prepared, and 3.9 mL of the DPPH reaction solution is mixed with 0.1 mL of the sample solution. After reacting in the dark for 20 min, the absorbance of the reaction solution is measured at 515 nm. The results are expressed as the Trolox micromolar equivalents (μmol Trolox / g) per gram of dry sample weight. The calculation formula is as follows: DPPH free radical scavenging rate (%) = ; In the formula: A0—absorbance value of 60% ethanol and DPPH reaction solution; A1—absorbance value of extract and DPPH reaction solution; A2—absorbance value of extract and anhydrous ethanol.

[0024] Example 1 This embodiment relates to a method for preparing roasted barley malt with high antioxidant activity, the steps of which are as follows: Step 1: Select 50g of plump, mold-free, and pest-free highland barley grains and soak them in 500mL of distilled water for 5 hours. During the soaking process, gently stir with a glass rod for 3-5 minutes every hour to ensure that the grains absorb water evenly and promote the precipitation of soluble impurities. After soaking, wash and centrifuge to remove residual water.

[0025] Step 2: Evenly spread two layers of moist filter paper in a 12cm diameter white porcelain dish. The filter paper should be saturated with water but without any visible water accumulation. Spread the soaked *Evodia rutaecarpa* seeds from Step 1 evenly on the filter paper, avoiding overlapping to ensure aeration and uniform germination. Place the porcelain dish in an incubator (light / dark cycle: 12 h / 12 ​​h, relative humidity 90%±5%) and incubate at a constant temperature of 25.0±0.5℃ for 42 h.

[0026] Step 3: Spray 5 mL of distilled water every 12 hours during cultivation to promote germination. Collect the buds and fibrous roots that have emerged from the basal radicle, and manually mix in the malt to prevent root entanglement.

[0027] Step 4: After germination, place the barley sprouts in a sealed container and replace the air with nitrogen to create a low-oxygen environment with an oxygen concentration of <5% for 1 hour.

[0028] Step 5: Dry the malt using a two-step drying method. First, dry the malt at a constant temperature of 60℃ in a hot air circulating drying oven for 2 hours to reduce the moisture content of the yellow malt from 42-46% (w / w) to 5% (w / w). During this period, check the moisture change and observe the color change every 30 minutes. Then, slowly raise the temperature to 80℃ and turn the malt to ensure even heating, so that the final moisture content of the yellow malt is 4% (w / w).

[0029] Step 6: Place the dried malt into a roasting container and heat it over a low flame to 230°C. Roast for 10 minutes, turning it over frequently. After roasting, let it cool in a desiccant (18-25°C, 15%-20% relative humidity).

[0030] Step 7: After roasting the malt, pre-cool it at -80℃ for 50 minutes, then freeze-dry it at -40℃ for 42 hours. Grind the malt into powder, collect the obtained freeze-dried roasted malt powder, and store it at low temperature.

[0031] Implementation results are as follows Figure 1-4The germination rate of the barley malt was measured to be 95%, the malt shedding rate after roasting was 20%, and the proportion of 4-6 mm malt sprouts was 28%. The malt was uniformly golden yellow to light brown in color, with a slightly glossy surface, no scorched or white spots, and had a rich roasted malt aroma. It was dry and crisp, easily crumbled by hand, with a clean cross-section, and no dampness or softness. When chewed, it was initially slightly sweet followed by a lingering sweetness, with the characteristic roasted grain aroma, and no raw, astringent, or bitter off-flavors. The roasted malt prepared in this example had a DPPH free radical scavenging capacity of 32.5 (μmol TE / g).

[0032] Example 2 This embodiment relates to a method for preparing roasted barley malt with high antioxidant activity, the steps of which are as follows: Step 1: Select 50g of plump, mold-free, and pest-free highland barley grains and soak them in 500mL of distilled water for 5 hours. During the soaking process, gently stir with a glass rod for 3-5 minutes every hour to ensure that the grains absorb water evenly and promote the precipitation of soluble impurities. After soaking, wash and centrifuge to remove residual water.

[0033] Step 2: Evenly spread two layers of moist filter paper in a 12cm diameter white porcelain dish. The filter paper should be saturated with water but without any visible water accumulation. Spread the soaked *Evodia rutaecarpa* seeds from Step 1 evenly on the filter paper, avoiding overlapping to ensure aeration and uniform germination. Place the porcelain dish in an incubator (light / dark cycle: 12 h / 12 ​​h, relative humidity 90%±5%) and incubate at a constant temperature of 25.0±0.5℃ for 42 h.

[0034] Step 3: Spray 5 mL of distilled water every 12 hours during cultivation to promote germination. Collect the buds and fibrous roots that have emerged from the basal radicle, and manually mix in the malt to prevent root entanglement.

[0035] Step 4: After germination, place the barley sprouts in a sealed container and replace the air with nitrogen to create a low-oxygen environment with an oxygen concentration of <5% for 1.5 hours.

[0036] Step 5: Dry the malt using a two-step drying method. First, dry the malt at a constant temperature of 60℃ in a hot air circulating drying oven for 2 hours to reduce the moisture content of the barley malt from 42-46% (w / w) to 5% (w / w). During this period, monitor the moisture content and observe the color change every 30 minutes. Then, slowly raise the temperature to 80℃ and turn the malt over to ensure even heating, so that the final moisture content of the barley malt is 4% (w / w).

[0037] Step 6: Place the dried malt into a roasting container, heat it over a low flame to 210°C, and roast for 10 minutes, turning it over frequently. After roasting, let it cool in a desiccator.

[0038] Step 7: After roasting the malt, pre-cool it at -80℃ for 45 minutes, then freeze-dry it at -40℃ for 48 hours. Grind the malt into powder, collect the obtained freeze-dried roasted malt powder, and store it at low temperature.

[0039] Implementation results are as follows Figure 1-4 The germination rate of the barley malt was measured to be 95%, the malt shedding rate after roasting was 16%, and the proportion of 4-6 mm malt sprouts was 26%. The malt was a uniform light brown color with a slightly glossy surface, without any charred or white spots. It had a rich roasted malt aroma, was relatively fragile to the touch, and felt slightly moist or soft. When chewed, it was initially slightly sweet followed by a lingering sweetness, with the characteristic roasted grain aroma and a slightly astringent taste. The DPPH free radical scavenging capacity of the roasted malt prepared in this example was 31.8 (μmol TE / g).

[0040] Example 3 This embodiment relates to a method for preparing roasted barley malt with high antioxidant activity, the steps of which are as follows: Step 1: Select 50g of plump, mold-free, and pest-free highland barley grains and soak them in 500mL of distilled water for 5 hours. During the soaking process, gently stir with a glass rod for 3-5 minutes every hour to ensure that the grains absorb water evenly and promote the precipitation of soluble impurities. After soaking, wash and centrifuge to remove residual water.

[0041] Step 2: Evenly spread two layers of moist filter paper in a 12cm diameter white porcelain dish. The filter paper should be saturated with water but without any visible water accumulation. Evenly scatter the barley seeds soaked in Step 1 onto the filter paper, avoiding overlapping to ensure aeration and uniform germination. Place the porcelain dish in an incubator (light / dark cycle: 12 h / 12 ​​h, relative humidity 90%±5%) and incubate at a constant temperature of 25.0±0.5℃ for 42 h.

[0042] Step 3: Spray 5 mL of distilled water every 12 hours during cultivation to promote germination. Collect the buds and fibrous roots that have emerged from the basal radicle, and manually mix in the malt to prevent root entanglement.

[0043] Step 4: After germination, place the barley sprouts in a sealed container and replace the air with nitrogen to create a low-oxygen environment with an oxygen concentration of <5% for 2 hours.

[0044] Step 5: Dry the malt using a two-step drying method. First, dry the malt at a constant temperature of 60℃ in a hot air circulating drying oven for 2 hours to reduce the moisture content of the barley malt from 42-46% (w / w) to 5% (w / w). During this period, monitor the moisture content and observe the color change every 30 minutes. Then, slowly raise the temperature to 80℃ and turn the malt over to ensure even heating, so that the final moisture content of the yellow malt inside the barley is 4% (w / w).

[0045] Step 6: Place the dried malt into a roasting container and heat it over a low flame to 250°C. Roast for 10 minutes, turning it over frequently. After roasting, let it cool in a desiccant.

[0046] Step 7: After roasting the malt, pre-cool it at -80℃ for 50 minutes, then freeze-dry it at -40℃ for 36 hours. Grind the malt into powder, collect the obtained freeze-dried roasted malt powder, and store it at low temperature.

[0047] Implementation results are as follows Figure 1-4 The germination rate of the barley malt was measured to be 95%, the malt shedding rate after roasting was 25%, and the proportion of 4-6 mm malt sprouts was 16%. The malt was uniformly golden yellow and light brown in color, with a slightly glossy surface, no scorched or white spots, and had a rich roasted malt aroma. It was easily crumbled by hand, without feeling damp or mushy. When chewed, it was initially slightly sweet followed by a lingering sweetness, with the characteristic roasted grain aroma and a slightly astringent taste. The DPPH free radical scavenging capacity of the roasted malt prepared in this example was 26.5 (μmol TE / g).

[0048] Example 4 This embodiment relates to a method for preparing roasted barley malt with high antioxidant activity. The method is the same as in Embodiment 1, except that the soaking time of barley grains in step 1 is 6 hours.

[0049] Implementation results are as follows Figure 1-4 The germination rate of barley malt was measured to be 85%, the malt shedding rate after roasting was 30%, and the proportion of 4-6 mm malt sprouts was 12%. The color was golden yellow to light brown, slightly charred or with white spots, with a rich malt aroma, dry and crisp, easily broken by hand, with a neat cross-section, and no dampness or softness. When chewed, it had the characteristic charred aroma of roasted grains, along with a slightly astringent, sour, and bitter aftertaste. The DPPH free radical scavenging capacity of the roasted malt prepared in this example was 28.8 (μmol TE / g).

[0050] Example 5 This embodiment relates to a method for preparing roasted barley malt with high antioxidant activity. The method is the same as in Embodiment 1, except that in step 2, the barley grains are cultured at a constant temperature of 20.0±0.5℃ for 42 h.

[0051] Implementation results are as follows Figure 1-4 The germination rate of the barley malt was measured to be 84%, and the malt shedding rate after roasting was 28%, with 16% of the sprouts being 4-6 mm in length. The malt was golden yellow to light brown in color, slightly charred or speckled, with a rich malt aroma, dry and crisp, easily crumbled by hand, with a clean cross-section, and no dampness or softness. It had the characteristic charred aroma of roasted grains when chewed. The DPPH free radical scavenging capacity of the roasted malt prepared in this example was 31.5 (μmol TE / g).

[0052] Example 6 This embodiment relates to a method for preparing roasted barley malt with high antioxidant activity. The method is the same as in Embodiment 1, except that in step 2, the barley grains are cultured at a constant temperature of 25.0±0.5℃ for 36 h.

[0053] Implementation results are as follows Figure 1-4 The germination rate of the barley malt was measured to be 78%, the malt shedding rate after roasting was 25%, and the proportion of malt sprouts with a length of 4-6 mm was 18%. The color was golden yellow to light brown, without any scorched or white spots, and it had a rich malt aroma. It was dry and crisp, easily crumbled by hand, with a clean cross-section, and no dampness or softness. When chewed, it had the characteristic roasted grain aroma, without any raw, astringent, or bitter off-flavors. The DPPH free radical scavenging capacity of the roasted malt prepared in this example was 34.8 (μmol TE / g).

[0054] Example 7 This embodiment relates to a method for preparing roasted barley malt with high antioxidant activity. The method is the same as in Embodiment 1, except that in step 2, the barley grains are cultured at a constant temperature of 25.0±0.5℃ for 48 h.

[0055] Implementation results are as follows Figure 1-4 The germination rate of the barley malt was measured to be 76%, the malt shedding rate after roasting was 25%, and the proportion of 4-6 mm malt sprouts was 18%. The color was golden yellow to light brown, without any scorched or white spots, with a rich malt aroma, dry and crisp, easily broken by hand, with a neat cross-section, and no dampness or softness. When chewed, it had the characteristic roasted grain aroma, without any raw, astringent, or bitter off-flavors. The DPPH free radical scavenging capacity of the roasted malt prepared in this example was 29.1 (μmol TE / g).

[0056] Comparative Example 1 This comparative example relates to the preparation of roasted malt based on traditional raw materials, namely barley husks. The difference from Example 1 is that barley husks are used for the preparation.

[0057] Implementation results are as follows Figure 1-4The germination rate of barley malt was measured to be 58%, and the malt shedding rate after roasting was 43%, with 12% of the sprouts being 4-6 mm in length. The color was a uniform golden yellow to light brown, with a slightly glossy surface, no scorched or white spots, a rich roasted malt aroma, dry and crisp, easily broken by hand, with an uneven fracture surface, and no dampness or softness. When chewed, it was slightly sweet with a raw, astringent, sour, and bitter aftertaste. Comparative studies showed that under the same processing conditions, barley malt exhibited a lower germination rate and a higher malt shedding rate. This difference is mainly due to the denser structure of the barley husk, resulting in a slower water penetration rate compared to barley, leading to insufficient germ activation. Additionally, the production of sticky substances in the barley endosperm during germination may promote malt adhesion and shedding between grains. The DPPH free radical scavenging capacity of the roasted malt prepared in this comparative example was 19.5 (μmol TE / g).

[0058] Comparative Example 2 This comparative example relates to a method for preparing roasted barley malt with high antioxidant activity. The difference from Example 1 is that in step 2, the barley grains are cultured at a constant temperature of 15.0±0.5℃ for 42 h.

[0059] Implementation results are as follows Figure 1-4 The germination rate of barley malt was measured to be 31%, and the malt shedding rate after roasting was 60%, with 3% of the sprouts being 4-6 mm in length. The malt was a uniform light brown color with a slightly glossy surface, free of scorched or white spots, and had a faint roasted malt aroma. It was dry and crisp, easily crumbled by hand, with a clean cross-section, and no dampness or softness. When chewed, it was slightly sweet with a raw, astringent, sour, and bitter aftertaste. The DPPH free radical scavenging capacity of the roasted malt prepared in this comparative example was 12.5 (μmol TE / g).

[0060] Comparative Example 3 This comparative example relates to a method for preparing roasted barley malt with high antioxidant activity. The difference from Example 1 is that in step 3, 10 mL of distilled water is sprayed on the barley grains every 12 hours during the cultivation period.

[0061] Implementation results are as follows Figure 1-4 The germination rate of barley malt was measured to be 15%, and the malt shedding rate after roasting was 63%, with 9% of the sprouts being 4-6 mm in length. The malt was a uniform dark yellow or light brown in color, with a slightly glossy surface, free of scorched or white spots, and had a faint roasted malt aroma. It was dry and crisp, easily crumbled by hand, with a clean cross-section, and no dampness or softness. When chewed, it was slightly sweet, with a raw, astringent, sour, and bitter aftertaste. The DPPH free radical scavenging capacity of the roasted malt prepared in this comparative example was 13.9 (μmol TE / g).

[0062] Comparative Example 4 This comparative example relates to a method for preparing roasted barley malt with high antioxidant activity. The difference from Example 1 is that step 4 adopts a conventional processing technology, and the germinated malt is dried in step 5 under normal air conditions.

[0063] Implementation results are as follows Figure 1-4 The germination rate of barley malt was measured to be 95%, the malt shedding rate after roasting was 23%, and the proportion of malts with a length of 4-6 mm was 26%. The DPPH free radical scavenging capacity of the roasted malt prepared in this comparative example was 10.5 (μmol TE / g). Due to the involvement of oxygen, the antioxidant components in the malt are easily oxidized and degraded, resulting in lower antioxidant activity of the roasted malt, a burnt taste on the surface of the product, a darker color, and a bitter taste. This process failed to effectively reduce oxidation, leading to the degradation of antioxidants, resulting in a burnt taste and color change. When chewed, it is slightly sweet with a raw, astringent, sour, and bitter aftertaste. High-temperature one-time drying easily leads to scorching of the malt surface (localized excessive temperature) while internal moisture remains (uneven heating), resulting in a dark color and a burnt taste in the finished product.

[0064] Comparative Example 5 This comparative example relates to a method for preparing roasted barley malt with high antioxidant activity. The difference from Example 1 is that step 5 adopts a traditional malt drying process, namely, using a single-stage constant temperature drying method, in which the malt is directly placed in a hot air circulating drying oven at 90°C and dried continuously for 3 to 4 hours until the moisture content drops to 4% (w / w).

[0065] Implementation results are as follows Figure 1-4 The germination rate of barley malt was measured to be 95%, and the malt shedding rate after roasting was 58%, with 4-6 mm malts accounting for 4%. It has a slightly sweet taste when chewed, but also a raw, astringent, sour, and bitter aftertaste. High-temperature single-stage drying easily leads to scorching of the malt surface (localized overheating) while internal moisture remains (uneven heating), resulting in a dark-colored finished product with a burnt and bitter taste. The DPPH free radical scavenging capacity of the roasted malt prepared in this comparative example was 13.5 (μmol TE / g).

[0066] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing roasted barley malt with enhanced antioxidant activity, characterized in that, The method includes the following steps: S1. Sprinkle the soaked barley seeds onto filter paper and incubate them in an incubator; S2. Spray water periodically to encourage barley seeds to germinate; S3. Place the germinated barley malt in a sealed container and replace the air with nitrogen to create a low-oxygen environment. S4. Use a two-step drying method until the barley malt is completely dried; S5. Place the dried barley malt into a roasting container and heat over a low flame, turning it over frequently. After roasting, let it cool in an environment of 18-25℃ and 15%-20% relative humidity.

2. The preparation method according to claim 1, characterized in that, Step S5 also includes the steps of pre-cooling the cooled highland barley roasted malt at low temperature, vacuum freeze-drying it, grinding it into powder, and collecting it to obtain roasted malt freeze-dried powder.

3. The preparation method according to claim 2, characterized in that, The low-temperature precooling has a cooling temperature of -82 to -78°C and a cooling time of 45 to 60 minutes; the vacuum freeze-drying has a freezing temperature of -45 to -35°C and a freezing time of 36 to 48 hours.

4. The preparation method according to claim 1, characterized in that, In step S5, the frying temperature corresponding to the gentle heating is 210~250℃, and the frying time is 5~15min.

5. The preparation method according to claim 1, characterized in that, In step S4, the two-step drying method includes: drying the barley malt at 50-65°C for 2-3 hours to reduce the moisture content of the barley malt from 42-46% (w / w) to 5-10% (w / w); and then slowly raising the temperature to 75-85°C so that the final moisture content of the barley malt is 3-4% (w / w).

6. The preparation method according to claim 1, characterized in that, In step S3, the oxygen concentration in the low-oxygen environment is <5%, and this is maintained for 1 to 4 hours before proceeding to the two-step drying process in step S4.

7. The preparation method according to claim 1, characterized in that, In step S2, 2-7 mL of distilled water is sprayed every 10-15 hours to promote malt germination.

8. The preparation method according to claim 1, characterized in that, In step S1, the germination temperature corresponding to the cultivation is 20~28℃, the relative humidity required for germination is 85~95%, and the germination time is 36~48h.

9. A roasted barley malt prepared by any one of claims 1-8, wherein the proportion of malt sprouts with a length of 4-6 mm is greater than 20%.

10. The use of roasted barley malt as described in claim 9 in the preparation of food or health products.

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