Preparation technology of healthy enzyme pickled vegetables

Abstract

The invention discloses a green preparation process of healthy enzyme pickled vegetables, which comprises the following steps: by taking vegetables such as radishes, papayas and asparagus lettuces as raw materials, carrying out cold sterilization with ozone water and low-temperature plasma, and carrying out vacuum-ultrasonic osmotic dehydration; inoculating a compound enzyme microbial agent which is compounded by lactobacillus plantarum, lactobacillus fermentum, lactobacillus paracasei and saccharomycetes and is embedded with papain and cellulase; performing dynamic variable-pressure pickling for 24 hours in 2% low-salt brine by adopting a 0.2 MPa pulse; and then carrying out three-stage precise fermentation at 28 DEG C to 25 DEG C to 20 DEG C for 60 hours to obtain the low-salt pickled vegetables of which the SOD is greater than or equal to 180U / g, the GABA is greater than or equal to 150mg / 100g and the nitrite is less than or equal to 0.5 mg / kg. And finally, carrying out ultrahigh-pressure instant fresh-keeping under 450MPa and 3 DEG C, and carrying out storage for 180d at normal temperature without preservatives. The product salt is less than or equal to 1.8%, viable bacteria are more than or equal to 1 * 10 CFU / g, the flavor is crisp and tender, the process is continuous and controllable, and the method is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation process of healthy enzyme sauce-pickled vegetables, and belongs to the technical field of fermented food processing, in particular to a healthy sauce-pickled vegetable green preparation process taking a composite enzyme inoculant as the core and low-temperature plasma-ultrasound synergistic pretreatment as the feature, which is especially suitable for the industrialized production of high-end sauce-pickled vegetables with low salt, no preservative, rich in active enzyme and dietary fiber for radish, papaya, lettuce and cucumber. BACKGROUND

[0002] Sauce-pickled vegetables are vegetable products obtained through pickling processing or products pickled by sauce, salt, sugar, vinegar and other raw materials, which are typical representatives and important components of traditional Chinese foods. Due to the unique flavors of fresh, sweet, crisp and tender, or salty, spicy and hot, and certain nutritional value, sauce-pickled vegetables have become indispensable condiment foods in people's daily life, which not only taste delicious, but also can stimulate appetite.

[0003] With the development of economy, sauce-pickled vegetables are gradually moving from homemade pickled home cooking to catering market, and becoming important leisure foods in outdoor activities such as suburban tour, mountain climbing, travel and camping. Originally, pickled and sauce-pickled vegetables were mainly used for storage, but now they have become light and delicious dishes for adjusting taste and stimulating appetite. Sauce-pickled vegetables are favored by consumers, especially white-collar workers, office workers and students, due to their functions of seasoning, accompanying meals, digestion and appetite stimulation.

[0004] A sour and spicy low-salt papaya sauce-pickled vegetable is disclosed in Chinese patent CN105029323A, which realizes the purposes of salt reduction, nitrite reduction and crispness preservation through solar-heat pump combined drying, ultrasonic initial pickling, lactic acid bacteria-yeast composite inoculation and cycle temperature control low-temperature fermentation, but it has the following problems: (1) It still uses traditional high-salt soy sauce (6-10%) for immersion, and the sodium content is relatively high; (2) The fermentation period is long (8-12 days), and the energy consumption is high; (3) The surface cold sterilization of raw materials is not performed, and the risk of post-contamination is high.

[0005] A sauce-pickled vegetable secondary fermentation process containing traditional Chinese medicines (sickle senna, Chinese wolfberry, etc.) is disclosed in Chinese patent CN108323732A, which shortens the period through 10-20℃ primary fermentation and 25-30℃ secondary fermentation, but it has the following problems: (1) The traditional Chinese medicine components are complex, and the flavor is easy to be too heavy, which is difficult to meet the taste of the public; (2) No directional enzyme inoculant is used, and the controllability of fermentation is poor; (3) The problem of rapid decrease of nitrite peak value is not solved.

[0006] The Chinese patent with the publication number CN111743117A discloses a health enzyme pickle vegetable process, which adopts lactic acid bacteria starter + papain combination to realize preservative-free and green production, but it has the following problems: (1) The lactic acid bacteria is a single strain, and the fermentation flavor is monotonous; (2) The targeted removal step of the biological membrane on the surface of raw materials and pesticide residues is lacked; (3) Pasteurization (70-80 DEG C, 10-15 min) leads to the inactivation of a large number of heat-sensitive enzymes and the decrease of functional value.

[0007] In summary, the existing technology has four pain points of high salt, single bacteria, long cycle and large nutrient loss, and a new process of "real low salt, multi-bacterial synergy, rapid and safe, and rich in active enzyme" is needed. SUMMARY

[0008] The present application overcomes the deficiencies of the prior art and provides a pickle vegetable preparation process containing active enzymes, low salt, no preservatives, long shelf life and rich flavor, which takes "low-temperature plasma-ultrasound synergistic cold sterilization, composite enzyme inoculant directional fermentation, dynamic pressure pickling and ultrahigh pressure instantaneous inactivation of bacteria" as the core.

[0009] To solve the above technical problems, the technical scheme adopted by the present application is as follows: 1. A preparation process of healthy enzyme pickle vegetables, characterized in that it comprises the following steps in sequence: a) low-temperature plasma-ultrasound synergistic cold sterilization step: after fresh vegetables are washed with ozone water, they are placed in a low-temperature plasma reaction chamber and treated under the conditions of 40 kHz and 150 W for 10-20 s, and then immediately transferred to a vacuum-ultrasonic permeation dehydration device and treated under the conditions of 40 kHz, 100 W, -0.08 MPa and 25 DEG C for 5-10 min, so that the surface microorganisms of the vegetables are reduced by greater than or equal to 4 log CFU / g and the water content is reduced to 65-75%; b) composite enzyme inoculant directional inoculation step: inoculate granular composite enzyme inoculant into the vegetables obtained in step a), and the inoculation amount is 0.15-0.30% of the mass of the vegetables, the composite enzyme inoculant is composed of Lactobacillus plantarum HM-1, Lactobacillus fermentum HF-2, Lactobacillus paracasei HP-3 and Cyberlindnera saturnispora YS-4 in a ratio of 3:2:2:1 in terms of viable bacteria, and is embedded in a chitosan-inulin- resistant dextrin carrier together with papain, cellulase and beta-glucosidase, and the total number of viable bacteria is greater than or equal to 1 x 10 0 CFU / g; c) dynamic variable pressure pickling step: the vegetables obtained in step b) are placed in a flexible fermentation bag with brine in a mass-volume ratio of 1:1.0-1:1.5, the brine containing NaCl 2.0-3.0%, erythritol 3-5%, L-malic acid 0.2-0.4%, and a program variable pressure is used: 0-2h normal pressure→2-6h pulse pressure 0.15-0.25MPa→6-24h normal pressure, temperature 20-25℃; d) multi-stage precise fermentation step: d1) start-up stage: 28-30℃ static for 6-8h, until pH drops to 4.9-5.1; d2) flavor enhancement stage: 25℃, ultrasonic-micro-oxygen coupling 40kHz / 80W, aeration amount 0.08-0.12vvm, for 10-14h; d3) enzyme production stage: 20℃ static for 40-50h, until SOD≥180U / g, GABA≥150mg / 100g, nitrite≤0.5mg / kg; e) ultra-high pressure instantaneous fresh-keeping step: the pickled vegetables obtained in step d) are immediately placed under 400-500MPa, 2-4℃ pressure for 2-4min, then vacuum-packed and deoxidizing agent is added, and the shelf life at room temperature is≥180d.

[0010] Further, the working gas of the low-temperature plasma reaction chamber is air or nitrogen-oxygen mixed gas, and the gas flow is 5-10L / min.

[0011] Further, the proportion of each enzyme activity in the composite enzyme agent is: papain 80000-100000U / g, cellulase 12000-18000U / g, and β-glucosidase 4000-6000U / g.

[0012] Further, the brine formula is as follows in terms of weight parts: 0.6-1.0 of Sichuan pepper, 0.4-0.8 of star anise, 1.0-1.5 of dried tangerine or orange peel, 1.2-2.0 of fresh ginger, 1.8-2.5 of garlic, 0.3-0.7 of red pepper, 3.5-4.5 of erythritol, 2.2-2.8 of low-sodium salt, 0.25-0.35 of L-malic acid, 0.04-0.06 of rosemary extract, and 100 of pure water.

[0013] Further, the pulse pressure waveform of the dynamic variable pressure pickling is a square wave, 30s pressurization / 30s pressure relief for one cycle.

[0014] Further, the ultrasonic-micro-oxygen coupling mode in the multi-stage precise fermentation step d2) is intermittent: ultrasonic on for 30s / off for 30s, and synchronous micro-oxygen on for 20s / off for 40s.

[0015] Further, the pressure medium of the super-high pressure fresh-keeping step is a water-propylene glycol mixture with a volume ratio of 9:1, and the medium temperature is 2-4 DEG C.

[0016] Further, the vegetables are selected from one or more of radish, papaya, lettuce, cucumber, carrot, celery, bamboo shoots.

[0017] Further, the vacuum quantitative packaging adopts a multi-layer co-extrusion high-barrier bag with an oxygen transmission rate of less than or equal to 0.5 cm3 / (m2·day·atm).

[0018] Further, the number of active lactic acid bacteria in the obtained pickled vegetable product is greater than or equal to 1 x 10 9 CFU / g, SOD is greater than or equal to 180 U / g, GABA is greater than or equal to 150 mg / 100 g, NaCl content is less than or equal to 1.8%, nitrite is less than or equal to 0.5 mg / kg, normal temperature shelf life is greater than or equal to 180 d, and no chemical preservatives are added.

[0019] Compared with the prior art, the present application has the beneficial effects that: the salt content of the pickled vegetable prepared according to the present application is less than or equal to 1.8%, which is much lower than that of the traditional product (6-10%); the fermentation period is shortened to less than or equal to 60 h by using the composite enzyme agent + dynamic variable pressure pickling, which is only 1 / 4 of that of the prior art; the active enzyme retention rate is greater than or equal to 90% by using low-temperature plasma-ultrasonic synergistic cold sterilization + super-high pressure fresh-keeping, and the whole process is free of heat sterilization; the product is rich in SOD, GABA, dietary fiber and small molecule peptides, and has the health care functions of antioxidant and intestinal flora regulation; and the process parameters of the present application can be programmed and controlled, and are suitable for industrialized continuous production of more than 200 kg / batch. DETAILED DESCRIPTION

[0020] The present application will be further described below in combination with specific examples.

[0021] Example 1: Low-salt enzyme pickled vegetable of white radish 1. Pretreatment of raw materials 100 kg of fresh white radish is washed with flowing water, then immersed in an ozone water vortex cleaning machine at 1.5 mg / L for 3 min. Subsequently, the radish is placed on a stainless steel mesh belt in a low-temperature plasma reaction chamber, and air with a flow rate of 8 L / min is introduced into the chamber at a frequency of 40 kHz and a power of 150 W for 15 s. The total number of surface bacterial colonies is reduced from 4.2 x 10 5 CFU / g to 2.1 x 10¹ CFU / g.

[0022] 2. Vacuum-ultrasonic permeation dehydration The radish is cut into 5 mm round pieces and placed in a vacuum-ultrasonic permeation tank. The ultrasonic frequency is set to 40 kHz and the power is set to 100 W. The vacuum degree is set to -0.08 MPa, and the operation is carried out at 25 DEG C for 8 min. The water content is reduced from 93% to 70%.

[0023] 3. Preparation of complex enzyme bacterial agent Take Lactobacillus plantarum HM-19 x 10 9 CFU, Lactobacillus fermentum HF-26 x 10 9 CFU, Lactobacillus paracasei HP-36 x 10 9 CFU, Cyberlindnera saturnispora YS-4 3 x 10 9 CFU, mixed uniformly with papain (90000 U / g) 30 g, cellulase (15000 U / g) 20 g, β-glucosidase (5000 U / g) 10 g, and chitooligosaccharide-inulin-resistant dextrin (2:1:1) 50 g as a freeze-drying protective agent, freeze-dried at -50°C to 4% moisture, crushed to 80 mesh, and 200 g of complex enzyme bacterial agent powder was obtained.

[0024] 4. Dynamic pressure pickling Brine formula: Zanthoxylum bungeanum 800 g, star anise 600 g, dried tangerine peel 1200 g, fresh ginger 1500 g, garlic 2000 g, red pepper 500 g, erythritol 4000 g, low-sodium salt 2500 g, L-malic acid 300 g, rosemary extract 50 g, and purified water 100 kg; boiled for 15 min and cooled to 25°C.

[0025] Radish slices were loaded into a flexible fermentation bag at a ratio of 1:1.2 (w / v) with brine, and the program was: 0-2 h at normal pressure; 2-6 h at square wave pulse 0.2 MPa, 30 s pressurization / 30 s pressure relief; 6-24 h at normal pressure; 25°C throughout. The final NaCl content was 1.72%.

[0026] 5. Multi-stage precise fermentation d1 start: add complex enzyme bacterial agent 200 g (0.2%), 28°C for 7 h, pH from 6.1 to 5.0; d2 flavor enhancement: switch to 25°C, 40 kHz / 80 W ultrasonic-micro-oxygen coupling, aeration 0.1 vvm, ultrasonic on 30 s / off 30 s, micro-oxygen on 20 s / off 40 s, run for 12 h; d3 enzyme production: 20°C for 48 h, detection: SOD 195 U / g, GABA 168 mg / 100 g, nitrite 0.31 mg / kg.

[0027] 6. Ultra-high pressure fresh-keeping Immediately after fermentation, load into a high-barrier bag, vacuum seal, and place in a 450 MPa water-propylene glycol medium at 3°C for 3 min, then store at room temperature in the dark. After 180 d, the viable count of lactic acid bacteria was 1.1 x 10 9 CFU / g, the crispness retention rate was 93%, and there was no bag swelling.

[0028] Example Two Low-salt Enzyme Sauerkraut of Papaya 1. Papaya was peeled and deseeded, and cut into 3 cm x 1 cm strips. Ozone water + low-temperature plasma were used as in Example One.

[0029] 2. Vacuum-ultrasonic dehydration was performed until the water content was 68%.

[0030] 3. The composite enzyme bacterial agent was prepared as in Example One, but the proportion of yeast bacteria was increased to 1.5 x 10 9 CFU to highlight the ester aroma.

[0031] 4. The brine was reduced in sugar to 3500 g erythritol, and the rest was the same as in Example One; the dynamic variable pressure parameters were unchanged.

[0032] 5. Fermentation: d1 30°C for 6 h; d2 26°C ultrasonic-microaerobic for 10 h; d3 18°C for 44 h. The product had SOD 188 U / g, GABA 155 mg / 100 g, total flavonoids increased by 1.9 times, and the total amount of ester flavor substances (ethyl acetate, ethyl hexanoate) increased by 42%.

[0033] 6. 450 MPa, 2°C for 2.5 min. The sensory score was > 90 points within 180 d shelf life.

[0034] Example Three Low-salt Enzyme Sauerkraut of Lettuce Stem-Cucumber 1. Lettuce stem and cucumber were cut into slices in a mass ratio of 7:3, and ozone water + low-temperature plasma were used as in Example One.

[0035] 2. Vacuum-ultrasonic dehydration was performed until the water content was 72%.

[0036] 3. 0.01% glucose oxidase was additionally added to the composite enzyme bacterial agent to inhibit browning.

[0037] 4. The brine was reduced in star anise to 400 g, and 300 g of lemon peel was added for flavoring, and the rest was the same as in Example 1; the dynamic variable pressure pulse was changed to 0.18 MPa, 35 s pressurization / 25 s depressurization.

[0038] 5. Fermentation: d1 29°C for 7.5 h; d2 25°C ultrasonic-microaerobic for 13 h; d3 19°C for 46 h. The final product had SOD 182 U / g, GABA 162 mg / 100 g, and a chlorophyll retention rate of 87%.

[0039] 6. 480 MPa, 3°C for 2 min. The product was jade green in color, crisp in texture, and had no discoloration or bag swelling within 180 d at room temperature.

[0040] Example Four Low-salt Enzyme Sauerkraut of Carrot-Celery 1. 1400 kg of carrot sticks and 600 kg of celery segments are automatically conveyed through a conveyor line and sprayed with 2.0 mg / L ozone water for 2 minutes. Then they pass through a continuous low-temperature plasma tunnel (bandwidth 1.2 m, length 3 m, 40 kHz, 180 W, air flow 12 L / min, belt speed 0.5 m / min).

[0041] 2. Vacuum-ultrasonic permeation dehydration unit (6m³ tank, four tanks in parallel), each tank holds 500kg, 40kHz, 120W, -0.09MPa, 20℃, 9min, output moisture content 69-71%.

[0042] 3. Scale-up preparation of compound enzyme agent: The strains were multiplied in a 10m³ fermenter for 24h at the same ratio. The bacterial sludge was collected by centrifugation, and the mixed enzyme solution was dried by a 50m² vacuum belt freeze dryer to obtain 4kg of finished agent; added at 0.2%.

[0043] 4. The total amount of brine is 2400L. The formula is the same as in Example 1. A 2t stainless steel dynamic pressure pickling tank is used. The program is as follows: 0–2h atmospheric pressure; 2–6h 0.2MPa pulse; 6–24h atmospheric pressure; temperature control 25±1℃.

[0044] 5. Multi-stage precise fermentation: d1 28℃ 7h; d2 25℃ ultrasound-micro-oxygen 12h; d3 20℃ 45h; Real-time online monitoring of pH, dissolved oxygen, and nitrite, with automatic recording.

[0045] 6. Ultra-high pressure preservation: Using a 600L ultra-high pressure autoclave, 450MPa, 3℃, 3min, 200kg per autoclave, 4 autoclaves can be processed per day.

[0046] 7. Quality inspection results: Live lactic acid bacteria count 1.3 × 10⁻⁶ 9 CFU / g, SOD 190U / g, GABA 172mg / 100g, NaCl 1.76%, nitrite 0.28mg / kg, commercially sterile for 180 days, meeting the requirements of GB2714-2015.

[0047] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A preparation process for a healthy enzyme-based pickled vegetable sauce, characterized in that, The steps are as follows: a) Low-temperature plasma-ultrasound synergistic cold sterilization step: After washing fresh vegetables with ozone water, they are placed in a low-temperature plasma reaction chamber and treated at 40kHz and 150W for 10-20s. Then, they are immediately transferred to a vacuum-ultrasound permeation dehydration device and treated at 40kHz, 100W, -0.08MPa, and 25℃ for 5-10min, so that the microorganisms on the surface of the vegetables are reduced by ≥4logCFU / g and the moisture content is reduced to 65-75%. b) Targeted inoculation step with compound enzyme agent: Inoculate the vegetables obtained in step a) with granular compound enzyme agent at an inoculation rate of 0.15-0.30% of the vegetable mass. The compound enzyme agent is composed of *Lactobacillus plantarum* HM-1, *Lactobacillus fermentum* HF-2, *Lactobacillus paracasei* HP-3, and yeast YS-4 in a viable count ratio of 3:2:2:1, and is co-encapsulated with papain, cellulase, and β-glucosidase in a chitosan oligosaccharide-inulin-resistant dextrin carrier. The total viable count is ≥1×10⁻⁶. 10 CFU / g; c) Dynamic pressure-switching pickling step: Place the vegetables obtained in step b) and the brine in a flexible fermentation bag at a mass-to-volume ratio of 1:1.0-1:1.

5. The brine contains 2.0-3.0% NaCl, 3-5% erythritol, and 0.2-0.4% L-malic acid. The pressure is programmed as follows: 0-2h atmospheric pressure → 2-6h pulse pressure 0.15-0.25MPa → 6-24h atmospheric pressure, temperature 20-25℃. d) Multi-stage precise fermentation steps: d1) Start-up phase: Let stand at 28-30℃ for 6-8 hours until the pH drops to 4.9-5.1; d2) Flavor enhancement stage: 25℃, ultrasound-micro-oxygen coupling 40kHz / 80W, ventilation rate 0.08-0.12vvm, lasting 10-14h; d3) Enzyme production stage: Let stand at 20℃ for 40-50 hours until SOD≥180U / g, GABA≥150mg / 100g, and nitrite≤0.5mg / kg; e) Ultra-high pressure instantaneous freshness locking step: Immediately place the pickled vegetables obtained in step d) under pressure of 400-500MPa and 2-4℃ for 2-4 minutes, then vacuum quantitatively package them and add deoxidizer. The shelf life at room temperature is ≥180 days.

2. The preparation process of a healthy enzyme-based pickled vegetable sauce according to claim 1, characterized in that, The working gas of the low-temperature plasma reaction chamber is air or a nitrogen-oxygen mixture, with a gas flow rate of 5-10 L / min.

3. The preparation process of a healthy enzyme-based pickled vegetable sauce according to claim 1, characterized in that, The enzyme activity ratios in the compound enzyme agent are as follows: papain 80,000-100,000 U / g, cellulase 12,000-18,000 U / g, and β-glucosidase 4,000-6,000 U / g.

4. The preparation process of a healthy enzyme-based pickled vegetable sauce according to claim 1, characterized in that, The brine formula, by weight, is as follows: Sichuan pepper 0.6-1.0, star anise 0.4-0.8, dried tangerine peel 1.0-1.5, ginger 1.2-2.0, garlic 1.8-2.5, red chili pepper 0.3-0.7, erythritol 3.5-4.5, low sodium salt 2.2-2.8, L-malic acid 0.25-0.35, rosemary extract 0.04-0.06, and purified water 100.

5. The preparation process of a healthy enzyme-based pickled vegetable sauce according to claim 1, characterized in that, The pulse pressure waveform of the dynamic pressure-variable pickling process is a square wave, with a cycle of 30s pressurization and 30s depressurization.

6. The preparation process of a healthy enzyme-based pickled vegetable sauce according to claim 1, characterized in that, The ultrasonic-micro-oxygen coupling mode in the multi-stage precise fermentation step d2) is intermittent: ultrasonic on for 30s / off for 30s, and synchronous micro-oxygen on for 20s / off for 40s.

7. The preparation process of a healthy enzyme-based pickled vegetable sauce according to claim 1, characterized in that, The pressure medium for the ultra-high pressure freshness-locking step is a water-propylene glycol mixture with a volume ratio of 9:1 and a medium temperature of 2-4℃.

8. The preparation process of a healthy enzyme-based pickled vegetable sauce according to any one of claims 1-7, characterized in that, The vegetables are selected from one or more of the following: radish, papaya, lettuce, cucumber, carrot, celery, and bamboo shoots.

9. The preparation process of a healthy enzyme-based pickled vegetable sauce according to any one of claims 1-7, characterized in that, The vacuum quantitative packaging uses a multi-layer co-extruded high-barrier bag with an oxygen permeability of ≤0.5cm³ / (m²·day·atm).

10. The preparation process of a healthy enzyme-based pickled vegetable sauce according to any one of claims 1-7, characterized in that, The viable count of live lactic acid bacteria in the obtained pickled vegetable products is ≥1×10⁻⁶. 9 CFU / g, SOD≥180U / g, GABA≥150mg / 100g, NaCl content≤1.8%, nitrite≤0.5mg / kg, shelf life at room temperature≥180d and no chemical preservatives required.