A fresh corn-based instant beverage powder and a method for preparing the same

Abstract

The present application relates to the technical field of corn product processing, in particular to a kind of instant powder based on fresh corn and a preparation method thereof, the fresh corn is pretreated, then the pretreated fresh corn is scalded, the scalded corn is threshed, then gradient drying is carried out, finally the dried corn kernels are micronized, to obtain the instant powder based on fresh corn as raw material.The preparation method of the instant powder based on fresh corn provided by the present application can retain flavor, can be quickly dissolved, cold water infusion is free of lumping, hot water infusion has low lumping rate, energy consumption is low, raw material adaptability is strong, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of corn product processing technology, specifically to an instant powder based on fresh corn and its preparation method. Background Technology

[0002] Currently, there are many mature corn flour processing technologies and fresh corn freeze-drying technologies on the market, but they all have many technological defects, such as clumping and loss of flavor. Due to the puffing process, the surface gelatinization degree of starch granules is >85%. When hot water is used for mixing, the gelatinized layer rapidly absorbs water and expands, forming a surface sticky barrier, which hinders the penetration of water into the powder and eventually forms hard core clumps. The puffing temperature is >150℃, which leads to excessive Maillard reaction, resulting in a free sugar loss rate of ≥40%, causing the sweetness to disappear. In addition, the existing technologies also have high energy consumption, poor raw material adaptability, and are not suitable for large-scale industrial production. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the purpose of this invention is to provide an instant powder based on fresh corn and its preparation method. The preparation method of the instant powder based on fresh corn provided by this invention can retain flavor, dissolve quickly, and has no clumping when mixed with cold water, and has a low clumping rate when mixed with hot water. It also has low energy consumption, strong raw material adaptability, and is suitable for large-scale industrial production.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A method for preparing an instant powder based on fresh corn includes the following steps:

[0006] After peeling and removing the silks from fresh corn, it is washed and then blanched to maintain the integrity of the cell structure, inactivate enzymes, soften the cell walls, and form an anti-dissolution gel layer.

[0007] After blanching, the corn is threshed and then subjected to gradient drying to control the rate of moisture migration and prevent starch granules from breaking down.

[0008] Finally, the dried corn kernels are micronized to form a capillary network, which accelerates the water molecule penetration rate, resulting in an instant powder based on fresh corn.

[0009] In a preferred embodiment of the present invention, the mechanism of blanching is to maintain the integrity of the cell structure, inactivate enzymes, soften the cell wall, and form an anti-dissolution gel layer. Blanching promotes partial gelatinization of starch, with a gelatinization degree of 15% to 20%. At the same time, pectin degrades to form a cell wall gelatinized starch complex layer, which inhibits the dissolution of soluble substances.

[0010] In a preferred embodiment of the present invention, the conditions for blanching and rinsing are that the water temperature is maintained at 95±0.5℃, the blanching and rinsing time is 8 minutes to 15 minutes, and the water is recycled during the blanching and rinsing process.

[0011] In a preferred embodiment of the present invention, the gradient drying system is operated by using a three-stage drying method to dry the corn kernels. The three-stage drying method includes a pre-drying stage, a main drying stage, and a balancing stage.

[0012] In a preferred embodiment of the present invention, surface dehydration is carried out when the temperature of the pre-drying section is 45℃~50℃, the reaction time is 0.5h~1h, and the wind speed is 0.5m / s~3m / s, so that the moisture content is reduced from 70% to 45%~50%.

[0013] In a preferred embodiment of the present invention, the temperature of the main section is 59℃~61℃, the reaction time is 1h~1.5h, and the wind speed is 0.5m / s~3m / s for the main dehydration process, reducing the moisture content from 45%~50% to 10%~15%.

[0014] In a preferred embodiment of the present invention, the temperature of the equilibrium section is 35℃~40℃, the reaction time is 0.5h~2h, and the wind speed is 0.5m / s~3m / s for moisture homogenization, so that the product moisture content is finally balanced to 8%~9%.

[0015] In a preferred embodiment of the present invention, the purpose of the gradient drying is to control the rate of moisture migration, avoid the disintegration of starch particles, thereby avoiding excessive Maillard reaction caused by high temperature (>65°C), increasing the retention rate of free amino compounds by 30%, and reducing the loss of corn characteristic flavor substances, such as furanones, by 40%.

[0016] In a preferred embodiment of the present invention, the micro-pulverization process is carried out by a dual-pulverization method. After drying, the corn kernels are first ground into corn kernels with a particle size of 2mm to 3mm by a primary crushing roller mill. Then, the 2mm to 3mm corn kernels are pulverized into corn flour of 80 mesh to 120 mesh by airflow classification. The purpose of the micro-pulverization process is to avoid the pulverization particles being too large, which would prevent the large particles from forming a capillary network and thus slow down the water molecule penetration rate.

[0017] In a preferred embodiment of the present invention, the pretreatment method is to peel and remove the silks from the raw fresh corn, and then wash it to remove surface impurities, so that the turbidity is ≤5 NTU.

[0018] Another object of the present invention is to provide an instant powder based on fresh corn, prepared by any of the above-described methods.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention provides an instant powder based on fresh corn, obtained through raw material pretreatment, blanching, gradient drying, and micro-pulverization. Blanching maintains cell structure integrity, rapidly deactivates enzymes, pregelatinizes starch, softens cell walls, and forms an anti-dissolution gel layer, promoting partial starch gelatinization. Simultaneously, pectin degradation forms a cell wall gelatinized starch composite layer, inhibiting the dissolution of soluble substances. Gradient drying controls the rate of water migration, preventing starch particle disintegration. Ultra-fine pulverization avoids excessively large particle size, which would prevent large particles from forming a capillary network, thereby slowing down the water molecule penetration rate.

[0021] 2. The process of this invention can preserve the flavor of the raw materials, does not clump when mixed with cold water, has a low clumping rate when mixed with hot water, has high solubility, low energy consumption, strong adaptability to raw materials, and is suitable for large-scale industrial production. Attached Figure Description

[0022] Figure 1 This is a flow chart illustrating the preparation process of an instant powder based on fresh corn according to the present invention. Detailed Implementation

[0023] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0025] Example 1

[0026] A method for preparing an instant powder based on fresh corn includes the following steps:

[0027] (1) Take fresh sweet corn from Wan Nuo 2018 for raw material pretreatment. First peel off the skin and remove the silk, then wash it. The turbidity reached by washing away surface impurities is 5 NTU.

[0028] (2) The pretreated fresh sweet corn is then blanched. The water temperature is maintained at 95℃ and the blanching time is 10 minutes. The blanching water is recycled.

[0029] (3) After blanching, the corn is cooled to room temperature, peeled, and then put into a corn thresher for threshing. The corn kernels are then dried in a heat pump integrated dryer using a three-stage drying method. The pre-drying section is set at 45℃, with a reaction time of 1 hour and a wind speed of 3 m / s for surface dehydration, resulting in a moisture content of 50%. The main drying section is set at 60℃, with a reaction time of 1.5 hours and a wind speed of 2 m / s for main program dehydration, resulting in a moisture content of 15%. The equilibrium section is set at 38℃, with a reaction time of 0.5 hours and a wind speed of 0.5 m / s for moisture homogenization, resulting in a moisture balance of 8.2%.

[0030] (4) Finally, the dried corn kernels are subjected to micro-pulverization. A double pulverization method is adopted. After drying, the corn kernels are first ground into particles with a diameter of about 2 mm by a primary crushing roller mill, and then pulverized by an ultra-micro pulverizer. Through airflow classification and built-in static elimination rod, 120 mesh instant powder based on fresh corn is obtained. According to the HPLC detection method based on GB 5009.8-2016, the free sugar retention rate is more than 93.5%, and the sensory score of fresh sweetness is 8.9 points out of 10.

[0031] Example 2

[0032] A method for preparing an instant powder based on fresh corn includes the following steps:

[0033] (1) Take fresh sweet corn from Wan Nuo 2018 for raw material pretreatment. First peel off the skin and remove the silk, then wash it. The turbidity reached by washing away surface impurities is 4 NTU.

[0034] (2) The pretreated fresh sweet corn is then blanched. The water temperature is maintained at 95℃ and the blanching time is 15 minutes. The blanching water is recycled.

[0035] (3) After blanching, the corn is cooled to room temperature, peeled, and then put into a corn thresher for threshing. The corn kernels are then dried in a heat pump integrated dryer using a three-stage drying method. The pre-drying section is set to a temperature of 50℃, a reaction time of 0.5h, and a wind speed of 3m / s for surface dehydration, with a moisture content of 47%. The main drying section is set to a temperature of 60℃, a reaction time of 1h, and a wind speed of 3m / s for main program dehydration, with a moisture content of 10%. The equilibrium section is set to a temperature of 40℃, a reaction time of 1.5h, and a wind speed of 1m / s for moisture homogenization, with the moisture content balanced to 8.0%.

[0036] (4) Finally, the dried corn kernels were subjected to micro-pulverization. A double pulverization method was adopted. After drying, the corn kernels were first ground into particles with a particle size of about 2 mm by a primary crushing roller mill, and then pulverized by an ultra-micro pulverizer. Through airflow classification and built-in static elimination rod, 100-mesh instant powder based on fresh corn was obtained. The free sugar retention rate was 93.5% and the sensory score of fresh sweetness was 8.9 points out of 10.

[0037] Example 3

[0038] A method for preparing an instant powder based on fresh corn includes the following steps:

[0039] (1) Take fresh sweet corn from Wan Nuo 2018 for raw material pretreatment. First peel off the skin and remove the silk, then wash it. The turbidity reached by washing away surface impurities is 4 NTU.

[0040] (2) The pretreated fresh sweet corn is then blanched. The water temperature is maintained at 95℃ and the blanching time is 8 minutes. The blanching water is recycled.

[0041] (3) After blanching, the corn is cooled to room temperature, peeled, and then put into a corn thresher for threshing. The corn kernels are then dried in a heat pump integrated dryer using a three-stage drying method. The pre-drying section is set at 48℃, with a reaction time of 2h and a wind speed of 2m / s for surface dehydration, resulting in a moisture content of 45%. The main drying section is set at 61℃, with a reaction time of 1.5h and a wind speed of 2m / s for main program dehydration, resulting in a moisture content of 13%. The equilibrium section is set at 37℃, with a reaction time of 1.5h and a wind speed of 2m / s for moisture homogenization, resulting in a moisture content of 8.1%.

[0042] (4) Finally, the dried corn kernels are subjected to micro-pulverization. A double pulverization method is adopted. After drying, the corn kernels are first ground into particles with a diameter of about 2 mm by a primary crushing roller mill, and then pulverized by an ultra-micro pulverizer. Through airflow classification and built-in static elimination rod, 110 mesh instant powder based on fresh corn is obtained. According to the HPLC detection method based on GB5009.8-2016, the free sugar retention rate is more than 93.5%, and the sensory score of fresh sweetness is 8.9 points out of 10.

[0043] Comparative Example 1

[0044] A method for preparing mature corn flour includes the following steps:

[0045] (1) Selection and cleaning: Select yellow corn kernels produced in the current year with a moisture content of ≤14%, no mold, and an impurity rate of <0.5%.

[0046] (2) Peeling and degerming: The corn kernels are polished to remove the seed coat, with a peeling rate of ≥95%, reducing the crude fiber content; the germ is separated using a degerming machine, with a yield of 8%. The germ is used for oil extraction, and the endosperm enters the next process.

[0047] (3) Crushing: Coarse crushing: After drying, the corn grits are initially crushed by a hammer mill with a particle size ≤500μm; Micro crushing: An air jet mill is used with a target particle size D50=80±10μm.

[0048] (4) Extrusion puffing, screw speed: 240 rpm; feed rate: 100 kg / h; water replenishment: add drinking water at 10% of the mass of puffed corn flour; temperature zone setting: the temperatures of temperature zone 1 to temperature zone 5 are 80℃, 100℃, 120℃, 130℃ and 140℃ respectively.

[0049] (5) Drying: The puffed corn strips are processed in a tubular dryer at 200°C until the moisture content is reduced to below 5%.

[0050] (6) Micro-grinding and sieving: the ratio of fast to slow roller speed of the grinding mill is 2.1, the working pressure is 0.6MPa, and it passes through an 80-mesh sieve.

[0051] Comparative Example 2

[0052] A method for preparing freeze-dried fresh corn powder includes the following steps:

[0053] (1) Selection criteria and variety requirements: Select sweet corn varieties with a sugar content of >8% and a maturity of milk stage. Process for 24 hours within 24 hours after harvesting; Raw material screening: Corn cobs should be free from insect infestation and mold, with plump kernels and a moisture content of 75%.

[0054] (2) Washing and threshing: High-pressure water spraying removes husks and impurities, and then a bubble cleaning machine removes surface microorganisms; mechanical threshing, with the cutter roller speed at 400 rpm, and the damage rate controlled at <3%.

[0055] (3) Blanching to kill enzymes, parameters: 90℃ hot water treatment for 120 seconds to sterilize, kill enzymes and soften cell walls.

[0056] (4) Pre-freezing and quick-freezing conditions: -60℃ ultra-low temperature freezer, quick-freezing for 6 hours.

[0057] (5) Vacuum freeze drying dehydration, vacuum degree: ≤5Pa, under extreme vacuum environment; temperature: -50℃→-20℃ gradient temperature increase, in order to avoid melting ice crystals; time: 24 hours.

[0058] (6) Coarse crushing: freeze-dried corn kernels are initially crushed to a particle size of ≤500μm by a hammer mill; airflow micro-crushing: air inlet temperature ≤40℃ to prevent local temperature rise and nutrient loss.

[0059] Comparative Example 3

[0060] A method for preparing an instant powder based on fresh corn includes the following steps:

[0061] (1) Take fresh sweet corn from Wan Nuo 2018 for raw material pretreatment. First peel off the skin and remove the silk, then wash it. The turbidity reached by washing away surface impurities is 4 NTU.

[0062] (2) The pretreated fresh sweet corn is then blanched. The water temperature is maintained at 95℃ and the blanching time is 3 minutes. The blanching water is recycled.

[0063] (3) After blanching, the corn is cooled to room temperature, peeled, and then put into a corn thresher for threshing. The corn kernels are then dried in a heat pump integrated dryer using a three-stage drying method. The pre-drying section is set at 45℃, with a reaction time of 1 hour and a wind speed of 3 m / s for surface dehydration, resulting in a moisture content of 70%. The main drying section is set at 60℃, with a reaction time of 1.5 hours and a wind speed of 2 m / s for main program dehydration, resulting in a moisture content of 15%. The equilibrium section is set at 38℃, with a reaction time of 0.5 hours and a wind speed of 0.5 m / s for moisture homogenization, resulting in a moisture balance of 8.2%.

[0064] (4) Finally, the dried corn kernels are subjected to micro-pulverization. A double pulverization method is adopted. After drying, the corn kernels are first ground into particles with a diameter of about 2 mm by a primary crushing roller mill, and then pulverized by an ultra-micro pulverizer. 120 mesh instant powder based on fresh corn is obtained by airflow classification and built-in static elimination rod. Insufficient blanching time leads to incomplete inactivation of PPO, resulting in enzymatic browning during storage. The residual activity of polyphenol oxidase is 32%. The instant powder browns after 24 hours, ΔE>5.

[0065] Comparative Example 4

[0066] A method for preparing an instant powder based on fresh corn includes the following steps:

[0067] (1) Take fresh sweet corn from Wan Nuo 2018 for raw material pretreatment. First peel off the skin and remove the silk, then wash it. The turbidity reached by washing away surface impurities is 4 NTU.

[0068] (2) The pretreated fresh sweet corn is then blanched. The water temperature is maintained at 95℃ and the blanching time is 10 minutes. The blanching water is recycled.

[0069] (3) After blanching, the corn is cooled to room temperature, peeled, and then put into a corn thresher for threshing. The corn kernels are then dried in a heat pump integrated dryer using a three-stage drying method. The pre-drying section is set at 45℃, with a reaction time of 1 hour and a wind speed of 3 m / s for surface dehydration, resulting in a moisture content of 70%. The main drying section is set at 70℃, with a reaction time of 1.5 hours and a wind speed of 2 m / s for main program dehydration, resulting in a moisture content of 15%. The equilibrium section is set at 38℃, with a reaction time of 0.5 hours and a wind speed of 0.5 m / s for moisture homogenization, resulting in a moisture balance of 8.2%.

[0070] (4) Finally, the dried corn kernels are subjected to micro-pulverization. A double pulverization method is adopted. After drying, the corn kernels are first ground into particles with a diameter of about 2 mm by a primary crushing roller mill, and then pulverized by an ultra-micro pulverizer. Through airflow classification and built-in static elimination rod, 120 mesh instant powder based on fresh corn is obtained. The temperature of the main drying section is too high, which triggers the Maillard reaction. The reducing sugar and amino acid covalently combine, resulting in the loss of sweet substances. The free sugar retention rate drops sharply to 68%, and the amount of 5-hydroxymethylfurfural (HMF) generated is 120 mg / kg, which exceeds the standard by 3 times.

[0071] Comparative Example 5

[0072] A method for preparing an instant powder based on fresh corn includes the following steps:

[0073] (1) Take fresh sweet corn from Wan Nuo 2018 for raw material pretreatment. First peel off the skin and remove the silk, then wash it. The turbidity reached by washing away surface impurities is 5 NTU.

[0074] (2) The pretreated fresh sweet corn is then blanched. The water temperature is maintained at 95℃ and the blanching time is 10 minutes. The blanching water is recycled.

[0075] (3) After blanching, the corn is cooled to room temperature, peeled, and then put into a corn thresher for threshing. The corn kernels are then dried in a heat pump integrated dryer using a three-stage drying method. The pre-drying section is set at 45℃, with a reaction time of 1 hour and a wind speed of 3 m / s for surface dehydration, resulting in a moisture content of 70%. The main drying section is set at 60℃, with a reaction time of 1.5 hours and a wind speed of 2 m / s for main program dehydration, resulting in a moisture content of 15%. The equilibrium section is set at 38℃, with a reaction time of 0.5 hours and a wind speed of 0.5 m / s for moisture homogenization, resulting in a moisture balance of 8.2%.

[0076] (4) Finally, the dried corn kernels are subjected to micro-pulverization. A double pulverization method is adopted. After drying, the corn kernels are first ground into particles with a diameter of about 2 mm by a primary crushing roller mill, and then pulverized by an ultra-micro pulverizer. Through airflow classification and built-in static elimination rod, 60-mesh instant powder based on fresh corn is obtained. The pulverized particles are too large, and the large particles cannot form a capillary network, which slows down the water molecule penetration rate. The cold water mixing time is >60 seconds and contains undissolved particles. The hydration index is only 0.8.

[0077] Results Analysis

[0078] The instant powder prepared based on fresh corn in Comparative Example 3 turned brown due to insufficient blanching time, resulting in enzyme residue. The blanching conditions were: water temperature 95℃, time: 3 minutes. The defect was that the powder turned brown after 24 hours, ΔE>5. The key test was the residual activity of polyphenol oxidase (PPO): 32%. The failure mechanism was that insufficient blanching time led to incomplete inactivation of PPO, resulting in enzymatic browning during storage.

[0079] The instant powder based on fresh corn prepared in Comparative Example 4 had an excessive Maillard reaction due to excessively high temperature in the drying section (70℃, 1.5h). The defect was a sharp drop in free sugar retention to 68%. The key test result was that the amount of 5-hydroxymethylfurfural (HMF) produced was 120 mg / kg, exceeding the standard by 3 times. The failure mechanism was that the Maillard reaction was initiated by excessive temperature, and the reducing sugars covalently bound to the amino acids, resulting in the loss of sweet substances.

[0080] The instant powder based on fresh corn prepared in Comparative Example 5 had deteriorated solubility due to excessively large particle size. The ultrafine grinding target was 60 mesh with a particle size of 250 μm. The defects were: cold water mixing time > 60 seconds and the presence of undissolved particles. Rheological analysis showed that the hydration index was only 0.8. The failure mechanism was that large particles could not form a capillary network, thus slowing down the water molecule permeation rate.

[0081] Figure 1 The present invention provides a process flow diagram for preparing an instant powder based on fresh corn. The process involves pre-treating the fresh corn, blanching the pre-treated fresh corn, threshing the blanched corn, gradient drying, and finally micro-pulverizing the dried corn kernels to obtain an instant powder based on fresh corn.

[0082] Table 1 compares the core nutritional components of fresh corn and naturally ripened corn.

[0083]

[0084] Note:

[0085] [1] Yang Minghua, Liu Qiang, Feng Guorui, et al. Analysis of suitable harvest period and grain moisture content of fresh waxy corn [J]. Xinjiang Agricultural Sciences, 2024, 61(07): 1626~1630.

[0086] [2] Sun Rui. Postharvest physiological study of fresh waxy corn ears [D]. Tianjin Agricultural College, 2012.

[0087] [3] Hao Xiaoqin. Study on the main nutritional quality and genetic laws of fresh sweet glutinous corn [D]. Guangxi University, 2006.

[0088] [4] An Lin, Cheng Yi, Luo Shangke, et al. Research progress on nutritional quality and influencing factors of fresh waxy corn [J]. Journal of Mountain Agriculture and Biology, 2023, 42(05):40~45.

[0089] [5] Yu Yao. Germplasm identification of anthocyanins and vitamin B2 in fresh corn kernels and dynamic study on their cumulative content [D]. Xinjiang Agricultural University, 2022.

[0090] [6] Wang Ke. Study on the accumulation of nutrients and quality formation of fresh corn kernels [D]. Anhui Agricultural University, 2024.

[0091] [7] Hu Xiaodan. Synthesis of anthocyanins in fresh corn kernels and their regulatory effect on glucose and lipid metabolism [D]. South China University of Technology, 2021.

[0092] [8] Li Ziqi. Research on nutritional quality evaluation system of fresh corn [D]. Chinese Academy of Agricultural Sciences, 2023.

[0093] As shown in Table 1, fresh corn is superior to naturally ripened corn in terms of active nutrients, including vitamins, antioxidants, and amino acids. However, the latter is more suitable as a staple food due to its high starch content. When choosing, health goals should be considered: fresh corn prioritizes nutrition, while ripe corn prioritizes energy.

[0094] Table 2 shows the agglomeration rate of the cold / hot water mixing process compared to the process of the present invention, the cooked corn puffing process, and the fresh corn freeze-drying process.

[0095]

[0096] Note: The experimental data in this paper are based on GB / T 18738-2006 Instant Soy Powder and ISO 5537 IDF 26 for the determination of milk powder caking rate. Specifically: Take 5g of the sample (m0) into a 100mL beaker, add 50mL of hot water above 65℃, stir with a glass rod for 1 minute, let stand for 10 minutes, filter the suspension using a 20-mesh standard sieve, pre-dry the sieve and weigh it (m1), retain the caking material, dry it at 105℃ to constant weight (m2), and take the average of three parallel tests. Caking rate Q = (m2−m1) / m0 × 100%. Industry standard: Instant powder caking rate <5%.

[0097] Table 2 shows that corn flour obtained through the extrusion process clumps regardless of whether it is mixed with cold or hot water. This is likely because during the extrusion process, the corn starch gelatinizes under high temperature and pressure, but the gelatinized starch molecules are extremely hydrophilic. When hot water comes into contact with the powder, the surface starch instantly absorbs water and gelatinizes, forming a high-viscosity, low-permeability gel layer that encapsulates the inner dry powder, preventing water penetration and creating a hard core that is "wet on the outside and dry on the inside." When mixed with cold water, the non-gelatinized starch absorbs water slowly, but the insufficiently dispersed powder particles still agglomerate due to local hydrogen bonding.

[0098] Freeze-dried fresh cornstarch also exhibits clumping when mixed with hot and cold water. This is likely because during the pregelatinization process before freeze-drying, the double helix structure of the amylopectin partially dissociates, forming highly hydrophilic gelatinized starch. When mixed with hot water at temperatures above 70°C, the surface starch instantly absorbs water and swells, forming a high-viscosity gel layer that coats the inner dry powder, hindering water penetration and creating a hard core that is "wet on the outside and dry on the inside." When mixed with cold water at temperatures below 25°C, the gelatinization temperature has not been reached. When the cornstarch temperature is ≥62°C, the starch cannot fully swell, and the particles agglomerate due to hydrogen bonding.

[0099] The agglomeration rate of cold water mixing in the process of this invention is 0%, and the agglomeration rate of hot water mixing is 1%. This may be because the gelatinization initiation temperature of corn starch is 62℃~72℃, and the drying temperature of 60℃ is strictly lower than this critical value, so that the starch granules maintain the complete A-type crystalline structure. At the same time, the hydroxyl groups of the complete starch granules are wrapped inside the granules, and they are not easily exposed and cross-linked during mixing.

[0100] Table 3 shows the cost, energy consumption, and total equipment price data for the process of this invention, the cooked corn puffing process, and the fresh corn freeze-drying process. All data are calculated based on a production capacity of 1T / H, and the equipment cost is expected to be recovered in 10 years.

[0101]

[0102] Table 4. Market Price Survey of Mainstream Products

[0103]

[0104] Table 3 shows that the extrusion process has the lowest cost among the three processes, while the freeze-drying process has the highest cost, mainly due to the raw material cost accounting for the vast majority. Combining Table 1 with the nutritional perspective, freeze-drying and the process of Example 1 of this invention are the optimal choices. Comparing freeze-drying and the process of Example 1 of this invention, the cost of the process of Example 1 of this invention is 7767.47 yuan / ton, which is 67.47% of the cost of freeze-drying. However, the equipment energy consumption and investment of the process of Example 1 of this invention are the lowest among the three processes, with energy consumption less than one-third and investment less than half of the other two.

[0105] According to the market price survey of mainstream products in Table 4, the average price of corn paste prepared by the puffing process of cooked corn is 23.69 yuan per 1000g, which is equivalent to 23,690.0 yuan per ton. The average price of corn flour prepared by the freeze-drying process of fresh corn is 149.375 yuan per 1000g, which is equivalent to 149,375.0 yuan per ton. Although the cost of this process is relatively high, we still have enough profit margin even if we sell it at the cheapest price of puffed corn flour. Therefore, we have certain advantages in terms of both price and nutrition.

[0106] The instant corn powder prepared by the process of this invention has more outstanding characteristics in terms of cold / hot water preparation compared with cooked corn powder prepared by the puffing process of cooked corn and fresh corn powder prepared by the freeze-drying process of fresh corn. It does not clump when prepared with cold water, has a low clumping rate when prepared with hot water, has high solubility, low energy consumption, strong raw material adaptability, and is suitable for large-scale industrial production.

[0107] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0108] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing an instant powder based on fresh corn as raw material, characterized in that, Includes the following steps: After peeling and removing the silks from the fresh corn, it is washed and then blanched to maintain the integrity of the cell structure, inactivate the enzymes, soften the cell wall, and form an anti-dissolution gel layer. After blanching, the corn is threshed and then subjected to gradient drying to control the rate of moisture migration and prevent starch granules from breaking down. Finally, the dried corn kernels are micronized to form a capillary network, which accelerates the water molecule penetration rate and yields an instant powder based on fresh corn. The conditions for blanching and rinsing are that the water temperature is maintained at 95±0.5℃, the blanching time is 8 to 15 minutes, and the water is recycled during the blanching and rinsing process; The gradient drying system operates by using a three-stage drying method to dry corn kernels. The three-stage drying method includes: a pre-drying stage, a main drying stage, and a balancing stage. The surface dehydration is carried out in the pre-drying section at a temperature of 45℃~50℃, a reaction time of 0.5h~1h, and an air velocity of 0.5m / s~3m / s, reducing the moisture content from 70% to 45%~50%. The main section operates at a temperature of 59℃~61℃, a reaction time of 1h~1.5h, and a wind speed of 0.5m / s~3m / s for the main dehydration process, reducing the moisture content from 45%~50% to 10%~15%. The equilibrium temperature is 35℃~40℃, the reaction time is 0.5h~2h, and the air velocity is 0.5m / s~3m / s for moisture homogenization, ultimately bringing the product moisture content to an equilibrium of 8%~9%. The micro-grinding process involves a dual-grinding method. After drying, the corn kernels are first ground into corn kernels with a particle size of 2mm to 3mm using a primary crushing roller mill. Then, the 2mm to 3mm corn kernels are pulverized into corn flour of 80 to 120 mesh through airflow classification.

2. The method for preparing instant powder based on fresh corn as raw material according to claim 1, characterized in that, The pretreatment method involves peeling and removing the silks from the raw fresh corn, then washing it to remove surface impurities, achieving a turbidity of ≤5 NTU.

3. An instant powder made from fresh corn, prepared by the method according to any one of claims 1 to 2.

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