A high-protein quinoa desaponin low-temperature processing method

Abstract

The application discloses a high-protein quinoa desaponin low-temperature processing method and belongs to the technical field of quinoa deep processing. A low-temperature negative pressure soaking all-in-one machine, a flexible microporous spraying desaponin device and a gradient low-temperature air-drying setting device are connected in series to form a continuous production line, and the raw material low-temperature pretreatment, negative pressure soaking saponin activation, microporous flexible spraying desaponin, low-temperature dewatering impurity removal, two-section gradient low-temperature air-drying setting and low-temperature screening vacuum packaging are sequentially completed. Pure water is used as a medium in the whole process, no chemical desaponin auxiliary agent is added, and no high-temperature treatment such as steaming, frying and frying is carried out, and the material temperature of each process is less than or equal to 30 DEG C. The negative pressure soaking makes the saponin in the shallow cortex of the kernel swell and activate, and the microporous flexible spraying separates the saponin, realizes efficient removal of saponin and high retention of protein, has low kernel breakage rate and is suitable for industrial batch production.

Description

Technical Field

[0001] This invention belongs to the field of quinoa agricultural product deep processing technology, specifically relating to a low-temperature processing method for desaponifying high-protein quinoa. Background Technology

[0002] Quinoa seeds are rich in high-quality plant protein, amino acids, and dietary fiber, making them a nutritious whole grain food. However, the outer and shallow outer layers of quinoa are rich in saponins, which give it a bitter taste and affect its palatability and digestibility. Commercially available quinoa generally needs to undergo saponin removal treatment before it can be consumed.

[0003] Existing deshaoling processes have significant drawbacks: high-temperature boiling easily leads to protein denaturation and nutrient loss; mechanical peeling results in high damage rates and incomplete deshaoling; and chemical deshaoling carries the risk of solvent residue. Conventional low-temperature, atmospheric-pressure water washing processes (25-30℃ spray washing for 15-30 minutes) achieve a saponin removal rate of only 60%-75%, requiring repeated washing 3-4 times, resulting in high energy and water consumption. The root cause lies in the difficulty for water molecules to effectively penetrate the dense skin layer and loosen bound saponins under atmospheric pressure.

[0004] Currently, most low-temperature processing technologies involve cooling individual processes, while heating stages still exist in the entire production line. A complete low-temperature processing chain, including negative pressure immersion, microporous spraying, and gradient air drying, has not been formed, resulting in poor product quality stability. Summary of the Invention

[0005] Technical issues to be resolved To address the problems of high-temperature protein damage, high grain breakage rate, incomplete desap removal, and poor mass production stability in existing quinoa desap removal processes, this invention provides a low-temperature physical processing method throughout the entire process, aiming to simultaneously achieve high saponin removal rate, high protein retention rate, and low grain breakage rate, and is suitable for continuous industrial production.

[0006] Technical solution

[0007] This invention provides a low-temperature processing method for desaponifying high-protein quinoa. The entire process involves no steaming, boiling, frying, or high-temperature heat treatment, and no chemical desaponifying agents are added throughout the entire process.

[0008] In this invention, all temperature parameters refer to the material temperature, which is monitored in real time by infrared thermometers at the discharge port or inside the chamber of each process; all negative pressure values ​​are negative pressure gauge pressures.

[0009] Core synergistic mechanism: Negative pressure soaking expands the micropores in the shallow cortex of quinoa grains and reduces the binding force between saponins and the cortex. Subsequently, an array of microporous sprays (spray water column diameter ≤ 1.2 mm) generates a high-density, low-impact micro-flow that precisely washes away loosened saponins without damaging the intact grains. After desap removal, a two-stage gradient air-drying process is employed: first, medium-temperature, high-volume airflow removes surface free water; then, low-temperature, low-volume airflow slowly releases internal bound water, following the natural moisture diffusion gradient and fixing the morphology and moisture content with minimal heat damage. These three processes form a closed-loop synergistic chain.

[0010] The synergistic mechanism of negative pressure soaking and microporous spraying is as follows: when soaking in pure water at normal pressure, water molecules have difficulty breaking through the dense cuticle layer and entering the superficial cortex; under negative pressure, the pores inside the grain expand, allowing water molecules to penetrate, which promotes the swelling of bound saponins and reduces the binding force between saponins and the cortex. Subsequently, microporous spraying can peel off and remove the activated saponins without damaging the integrity of the grain.

[0011] The specific steps are as follows: S1. Raw material pretreatment: Select quinoa grains that are free from mold and have a fullness of ≥95%, remove impurities by air separation and gravity grading, and control the moisture content of the grains to 10%~12%; material temperature ≤28℃.

[0012] S2. Low-temperature negative pressure soaking and activation: Pretreated quinoa is fed into a low-temperature negative pressure soaking machine, using purified water (conductivity ≤5μS / cm) as the medium, and soaked under closed negative pressure conditions; material temperature 25~30℃, negative pressure gauge pressure -0.03~-0.06MPa, soaking for 60~90min; jacket water cooling constant temperature, negative pressure water vapor is recovered by condenser; the equipment is started in sequence by electrical interlock, and if any equipment fails, the upstream feed will stop immediately and maintain the current state, and will automatically recover after the fault is cleared; within 5min after soaking, it is transferred to the spraying equipment, and atomized moisturizing (spray volume ≤0.5L / min) is used during the transfer to keep the surface of the grains moist.

[0013] S3. Flexible microporous low-temperature desap removal: Activated quinoa is fed into a flexible microporous spray desap removal device, sprayed with purified water without adding chemical additives. The activated saponins are removed by array microporous spraying in conjunction with a flexible feeding mechanism. The total spray flow rate is 15~30L / min, the feeding mechanism speed is 10~40r / min, and the desap removal time is 8~12min. The spray water is recycled after being filtered through three stages of sedimentation (200 mesh, 50μm, 5μm) and replaced for each batch. The water consumption is ≤2.5m³ / ton of raw material.

[0014] S4. Low-temperature draining and impurity removal: Vibrate and drain for 3-5 minutes under low-temperature conditions to remove free water and detached saponin residue from the surface and prevent secondary adhesion of residue.

[0015] S5. Gradient Low-Temperature Air Drying and Shaping: The material is evenly spread on the conveyor belt by a vibrating spreader (material layer thickness 2~3cm) and enters the gradient air drying equipment; the first stage material temperature is 28~30℃, wind speed is 2.5~3.0m / s, and the treatment time is 20min to remove surface free water; the second stage material temperature is 22~27℃, wind speed is 1.8~2.4m / s, and the treatment time is 25min to remove bound water; the finished product moisture content is 11%~13%.

[0016] S6. Screening and Packaging: Color sorting removes discolored and moldy particles under low temperature conditions, air sorting removes light impurities, and vacuum packaging is performed after quality inspection meets the standards.

[0017] Dedicated processing equipment: The low-temperature negative pressure soaking integrated machine is a sealed tank with a jacketed water-cooled heat exchange layer, a negative pressure air extraction interface and a condensate trap. The tank is driven by a drive device to swing back and forth around a horizontal axis to realize the turning of materials. The discharge port is connected to the spraying equipment through an airtight rotary valve.

[0018] The flexible microporous spray desoaping equipment is a horizontal sealed drum with an array of microporous spray pipes with a diameter of 0.8~1.2mm at the center, achieving a filtration accuracy of ≤0.5μm. It is connected to an external compressed air backflushing interface (0.4~0.6MPa online backflushing during shutdown). The inner wall of the drum is evenly distributed with four spiral silicone feeding ribs along the circumference, with a spiral angle of 15°~25°. When the drum rotates, the feeding ribs push the grains towards the discharge end and tumble them. The discharge port is connected to the air drying equipment via a vibrating conveyor trough.

[0019] The gradient low-temperature air drying and shaping equipment is a segmented sealed air chamber with a first and second independent air drying chamber and an airtight isolation door between the chambers. Each chamber is independently equipped with a temperature control module, a variable frequency speed control fan and an airflow regulating baffle, and is equipped with a micro positive pressure exhaust (+50~+100Pa) to prevent airflow from mixing. Each piece of equipment is equipped with a quick-opening maintenance door.

[0020] Beneficial effects

[0021] The material temperature is ≤30℃ throughout the process, without steaming, boiling, frying or high-temperature treatment, which effectively avoids protein denaturation and loss of water-soluble nutrients, and maximizes the preservation of the high protein nutritional value of quinoa.

[0022] Negative pressure soaking allows water molecules to penetrate the dense cortex and loosen the bond between saponins and cortex. Combined with arrayed micropores and low-impact spraying, this achieves efficient saponin removal without relying on high temperatures or chemical additives. The absence of hard contact structure reduces the grain breakage rate to below 0.8%, completely eliminating bitterness and off-flavors.

[0023] The entire process uses purified water as the medium, without adding any chemical soap-removing agents, resulting in a safe and clean finished product that meets high-end food production standards.

[0024] The three processes of negative pressure soaking, flexible spraying, and gradient air drying work together in a coordinated manner. The absence of any one of these processes will significantly affect the desoaping rate or lead to protein loss. The process is stable, suitable for continuous mass production, and produces products with uniform quality and long storage period, making it highly valuable for industrialization.

[0025] This invention is not a simple superposition of three known unit operations. Comparative experiments have shown that: canceling negative pressure (replacing it with long-term immersion at normal pressure), replacing gradient air drying with single-stage constant temperature, and using traditional high-temperature processes cannot simultaneously achieve the comprehensive effect of high saponin removal rate, high protein retention rate, and low breakage rate of this invention.

[0026] Any routine adjustments made by those skilled in the art based on the parameter ranges described in this invention are within the scope of protection of this invention. Attached Figure Description

[0027] Figure 1. Overall processing flow chart; Figure 2. Schematic diagram of the dedicated hardware device structure.

[0028] Figure label: 1-Low-temperature negative pressure soaking integrated machine; 2-Jacketed water-cooled heat exchange layer; 3-Negative pressure exhaust port; 4-Condensate trap; 5-Airtight rotary valve; 6-Flexible microporous spray soap removal equipment; 7-Array-type microporous spray pipe; 8-Flexible material feeding mechanism; 9-Compressed air backflush port; 10-Vibrating conveyor trough; 11-Gradient low-temperature air drying and shaping equipment; 12-First air drying chamber; 13-Second air drying chamber; 14-Airtight isolation door; 15-Temperature control module; 16-Variable frequency speed control fan; 17-Airflow regulating baffle; 18-Vibrating material distributor. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. These embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection. In all embodiments, the temperature refers to the material temperature, which is monitored in real time by an infrared thermometer. Example 1

[0030] S1. Raw material pretreatment: Material temperature ≤28℃, quinoa grain fullness ≥95%, crude protein content 14.5% (GB 5009.5-2016), and grain moisture content 11.2%; S2. Low-temperature negative pressure soaking: Material temperature 28℃, negative pressure gauge pressure -0.04MPa, soaking for 75 minutes; S3, Flexible microporous desoaping: Material temperature 30℃, spray flow rate 22L / min, feeding speed 20r / min, desoaping for 10min; S4. Low-temperature draining: Vibration draining for 4 minutes; S5, Gradient air drying: First stage 29℃, 2.8m / s, 20min; Second stage 25℃, 2.1m / s, 25min, finished product moisture content 12.1%; S6. Color sorting removes discolored and moldy particles, air sorting removes light impurities, and vacuum sealing is performed.

[0031] Finished product: saponin residue 0.11 mg / g, saponin removal rate 93.5%, protein retention rate 96.2%, and new breakage rate before color sorting processing 0.6%. Example 2

[0032] S1, Same as Example 1; S2, material temperature 25℃, negative pressure gauge pressure -0.03MPa, soaking for 90min; S3, material temperature 28℃, spray flow rate 18L / min, feeding speed 15r / min, desoaping 12min; S4, Same as Example 1; S5, First segment 28℃, 2.5m / s, 20min; Second segment 22℃, 1.8m / s, 25min.

[0033] Finished product: saponin residue 0.13 mg / g, saponin removal rate 92.1%, protein retention rate 97.0%, and new breakage rate before color sorting processing 0.5%.

[0034] Comparative test Control Group 1 (Long-term soaking under normal pressure): The negative pressure soaking in S2 was replaced with normal pressure pure water soaking, and the soaking time was extended to 45 minutes. The rest was the same as in Example 1. The saponin removal rate was only 78.2%, indicating that the negative pressure condition, rather than simply extending the soaking time, is the key factor in activating saponins.

[0035] Control group 2 (constant temperature air drying): Replacing the S5 gradient air drying with a single-stage air drying at 30℃ constant temperature, 2.5m / s, and 45min, the protein retention rate decreased to 87.3%.

[0036] Comparative group 3 (traditional high-temperature process): Boiling at 85℃ for 15 minutes, protein retention rate 81.5%, damage rate 2.3%.

[0037] The above comparative tests demonstrate that negative pressure immersion, flexible spraying, and gradient air drying work synergistically and are indispensable, resulting in a comprehensive performance that is significantly better than existing processes.

[0038] Adaptive adjustments: In actual production, the soaking time and air-drying conditions can be routinely adjusted within the range of the parameters in the claims, based on the quinoa variety, initial moisture content, and ambient temperature and humidity. This is within the scope of knowledge of those skilled in the art.

[0039] Detection methods 1. Saponin content (HPLC method): The sample was pulverized through a 40-mesh sieve, and 2.0 g was accurately weighed. 25 ml of 70% methanol was added, and the sample was ultrasonically extracted for 30 min (250 W, 40 kHz). The mixture was then filtered and brought to a final volume of 50 ml. Chromatographic conditions: C18 column (4.6 mm × 250 mm, 5 μm), mobile phase methanol:water = 75:25, flow rate 1.0 ml / min, column temperature 30℃, detection wavelength 203 nm, injection volume 20 μL, and oleanolic acid external standard quantification.

[0040] 2. Protein content: GB 5009.5-2016.

[0041] 3. Protein retention rate (dry matter basis): (finished product dry matter protein content × finished product dry matter mass) / (raw grain dry matter protein content × raw grain dry matter mass) × 100%.

[0042] 4. Saponin removal rate: (mass of saponins removed / total saponins in raw grain) × 100%.

[0043] 5. Grain breakage rate (newly added before color sorting): Randomly select 1000 grains of S2~S5 processed products, and count the percentage of broken grains. Excluding the initial broken grains of raw materials and secondary breakage caused by color sorting air blowing (≤0.3MPa).

Claims

1. A low-temperature processing method for removing saponins from high-protein quinoa, characterized in that, It consists of the following steps executed in sequence, with no additional processing steps inserted between them: S1. Raw material pretreatment: Select plump and undamaged quinoa grains, and remove impurities and shriveled grains through wind separation and gravity grading to complete purification and grading; S2. Low-temperature negative pressure soaking and activation: The pretreated quinoa is sent into a low-temperature negative pressure soaking machine, using purified water as the soaking medium, and is soaked and activated under a closed negative pressure condition to fully swell and activate the saponins in the surface and shallow cortex of the grains. S3, Flexible microporous low-temperature desap removal: The activated quinoa is fed into the flexible microporous spray desap removal equipment, using purified water as the spray medium, and the saponin impurities are removed by array microporous spraying in conjunction with a flexible feeding mechanism. S4. Low-temperature draining and impurity removal: under low-temperature conditions, vibrating draining removes free water and saponin residue from the surface of the grains. S5. Gradient low temperature air drying and shaping: The gradient low temperature air drying and shaping equipment first removes the free water on the surface of the grains in the first stage of air drying, and then removes the bound water inside the grains in the second stage of air drying, thereby controlling the moisture content and fixing the shape of the grains. S6. Screening and Packaging: Color sorting removes discolored and moldy particles under low temperature conditions, air sorting removes light impurities, and vacuum packaging is performed after quality inspection to obtain low saponin quinoa finished product; The entire processing process does not involve steaming, boiling, frying, or high-temperature heat treatment, and no chemical desap removal agents are added throughout the process, and the material temperature in each process does not exceed 30℃.

2. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: Step S2 The low-temperature negative pressure immersion integrated machine is a sealed tank. The tank is equipped with a jacketed water-cooled heat exchange layer and a negative pressure air extraction interface on the outside. The negative pressure interface is connected to a condensate trap and a vacuum pump. The tank is driven by a drive device to reciprocate around a horizontal axis with a swing angle of ±15°~±30° and a swing frequency of 6~12 times / min.

3. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: Step S3 The flexible microporous spray desoaping device is a horizontal sealed drum. The center of the drum is equipped with an array of microporous spray pipes with a diameter of 0.8~1.2mm. The spray pipes are connected to a compressed air backflush interface. The inner wall of the drum is equipped with a flexible material feeding mechanism, which is a spiral silicone material feeding rib evenly distributed along the circumference of the inner wall of the drum. Step S5 The gradient low temperature air drying and shaping device is a segmented sealed air chamber with independent first and second air drying chambers. An airtight isolation door is provided between the two chambers. Each chamber is independently equipped with a temperature control module, a variable frequency speed control fan and an airflow regulating baffle.

4. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: In step S1, the material temperature during the pretreatment process is ≤28℃.

5. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: In step S2, the material temperature is 25~30℃, and the negative pressure gauge pressure is... Soak for 60-90 minutes.

6. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: In step S3, the total spray flow rate is 15~30L / min, the rotation speed of the flexible feeding mechanism is 10~40r / min, and the soap removal time is 8~12min.

7. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: The vibration drainage time in step S4 is 3-5 minutes.

8. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: In step S5, the material temperature in the first stage is 28~30℃, the wind speed is 2.5~3.0m / s, and the treatment time is 20min; the material temperature in the second stage is 22~27℃, the wind speed is 1.8~2.4m / s, and the treatment time is 25min; before entering the first drying chamber, the material is spread on the conveyor belt by a vibrating spreader, and the material layer thickness is 2~3cm; the moisture content of the finished product is 11%~13%.

9. The low-temperature processing method for desaponifying high-protein quinoa according to claim 1, characterized in that: S1 quinoa grains have a plumpness of ≥95%, a moisture content of 10%~12%, and a crude protein content of ≥14.0%.

10. The high-protein, low-saponin quinoa product prepared by the method according to any one of claims 1 to 9, characterized in that: The residual saponin content is ≤0.15mg / g, the saponin removal rate is ≥92%, the protein retention rate is ≥95%, and the newly added seed breakage rate during the pre-color sorting processing is ≤0.8%; the seed breakage rate refers to the percentage of broken seeds generated during the processing of raw materials after S1 purification in S2~S5, excluding the initial broken seeds of raw materials and secondary breakage caused by color sorting rejection.

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