Preparation method of'secondary excitation 'chili oil

Abstract

The invention discloses a preparation method of'secondary excitation 'chili oil, and belongs to the technical field of food. Through microwave pretreatment and gradient oil temperature excitation process innovation, high-quality preparation of the chili oil is realized on the premise of not adding chemical antioxidants. Unique 180 DEG C / 140 DEG C double-temperature-section control is adopted, so that aroma excitation is completed, and natural antioxidant components are generated through a Maillard reaction. The light transmittance of the product is greater than or equal to 95% through a three-stage physical purification process, the shelf life reaches 18 months, and the product conforms to the development trend of clean label food.

Description

Technical Field

[0001] The present invention belongs to the field of food processing technology, and specifically relates to a chili oil preparation system and method based on microwave field effect and gradient oil phase excitation, which is particularly suitable for the industrial production of flavored chili oil products with high spiciness retention rate and natural stability. Background Art

[0002] Chili oil, an indispensable condiment in global culinary culture, has permeated every aspect of the food industry. According to statistics, the global chili oil market is expected to exceed US$5.2 billion in 2023. Product forms have expanded from basic seasonings to complex seasoning packets, core ingredients for prepared dishes, and coatings for snack foods. In the Chinese restaurant market, approximately 87% of Sichuan and Hunan cuisines use chili oil as a flavor base. Internationally, specialty foods such as Southeast Asian Tom Yum Goong, Mexican chili sauce, and Italian spicy olive oil all use chili oil as a core flavoring medium. Consumer demand for high-quality chili oil reflects refined standards based on "three degrees and three qualities": layered spiciness (a balance between initial pungency and lingering aftertaste), complex aroma (must include six or more aroma components such as toasted, fruity, and smoky notes), translucent color (red pigment retention >90%), oxidative stability (shelf life ≥12 months), flowability (viscosity 20-30 mPa·s at 25°C), and clean label (no chemical additives). These stringent standards are in sharp conflict with traditional production processes, giving rise to the need for technological upgrades.

[0003] The current mainstream production process mainly relies on thermodynamics to extract flavor substances, which can be divided into three major technical routes: the first is the hot oil drench method, which drenches the crushed Erjingtiao dried chili peppers in batches into 150-190°C hot oil. The thermal shock causes the chili skin to rupture and release active ingredients. A typical process, such as the three-drench and three-shock method used in CN107518123A, has simple equipment but has the disadvantages of large oil temperature fluctuations (±15°C) and low capsaicin dissolution rate (68-72%). The second is the constant temperature extraction method, which mixes chili powder with cold oil and then increases the temperature gradually, such as the low-temperature aroma initiation-medium-temperature enrichment-high-temperature flavor determination process disclosed in CN112220124B. Although it can improve the retention rate of flavor substances, it leads to a production cycle of 8-10 hours, and static extraction accelerates oil oxidation (the peroxide value is 35% higher than the leaching method); the third is modern assisted extraction method, including ultrasonic assistance (20-40kHz cavitation effect destroys cell walls), microwave pretreatment (800W treatment for 3 minutes increases extraction efficiency to 79%) and enzymatic hydrolysis assistance (cellulase optimizes cell wall decomposition), but these technologies generally have high equipment investment (ultrasonic equipment > 500,000 yuan), by-product risks (microwave treatment causes benzopyrene to exceed the standard by 1.5 times) or poor product stability (enzymatic hydrolysis causes NTU value > 25) and other problems, which restrict industrial application.

[0004] The existing technical system still has significant defects in core indicators: first, the extraction efficiency of flavor substances is low. Electron microscopy analysis shows that the pore size of the pepper cell wall after traditional processing is less than 0.5μm, which hinders the diffusion of large molecular substances, resulting in an extraction rate of capsaicinoids less than 70%, and an imbalance in the isomer ratio (cis / trans = 1:3.2), resulting in a strong spicy taste but insufficient sweetness; second, the aroma components are not fully stimulated. GC-MS testing shows that commercially available products contain only 28-35 volatile components, and the key aroma substance 2-methoxy-3-hydroxy-1-methyl-1-thiazolinone is not fully stimulated. The isobutylpyrazine retention rate is less than 55%, due to the runaway Maillard reaction at high temperatures, which produces a large amount of pyrazine derivatives that mask the original aroma. The emission rate of low-boiling-point aldehydes reaches 60%. Furthermore, quality stability control is weak, with accelerated oxidation tests showing a 120-150% increase in peroxide value. This is attributed to metal ion catalysis (iron equipment causes Fe₂+ migration >3 mg / kg), uncontrolled water activity (a water content of 0.15-0.3% promotes free radical reactions), and a limited antioxidant system (BHT decomposition rate >70% at high temperatures). This exposes a deep contradiction in the industry: the conflict between consumers' pursuit of natural products and the reality of companies' reliance on chemical additives, as well as the need for process upgrades and the cost pressure of transformation. The urgent need is to develop a next-generation technology solution that balances efficient extraction with natural stability. Summary of the Invention

[0005] The invention provides a preparation method of "secondary excitation" chili oil, so as to solve the problems of low utilization rate of chili flavor substances and insufficient fragrance in traditional chili oil products.

[0006] To achieve the above object, the present invention provides a method for preparing "secondary excitation" chili oil, which is characterized by comprising the following process steps and parameter control:

[0007] Step 1: Raw material pretreatment

[0008] Select Erjingtiao dried chili peppers with a moisture content of ≤8%, remove the stems and impurities, and crush them into uniform particles with a particle size of 1-3 mm using a toothed disc crusher. During the crushing process, nitrogen protection is introduced to control the temperature of the crushing chamber to ≤30°C;

[0009] Optimal solution: The crushed particle size gradient is controlled to be 1-2 mm (accounting for 70%) and 2-3 mm (accounting for 30%) to balance the subsequent microwave activation efficiency and the oil phase extraction effect.

[0010] Step 2: Microwave Activation

[0011] The chili granules were spread on the microwave reactor conveyor belt (the thickness of the material was 2-3 cm) and subjected to a three-stage treatment at a microwave frequency of 2450 MHz:

[0012] a) First stage: 700W treatment for 1 minute, the material temperature rises to 60±5℃;

[0013] b) Second stage: 800W for 1.5 minutes, until the core temperature reaches 90±5°C;

[0014] c) The third stage: 600W for 1 minute to soften the cell wall;

[0015] Optimal solution: Simultaneously introduce 50-60°C hot air (wind speed 1.5m / s), and control the humidity at 15-20% to achieve microwave-hot air synergistic dehydration.

[0016] Step 3: Gradient oil phase excitation

[0017] The activated chili granules are mixed with cooking oil in a mass ratio of 1:3-5 and processed in stages using a PID temperature control system:

[0018] a) First excitation stage: heat to 180±5°C at a rate of 8-10°C / min, hold for 3-5 minutes, and start variable frequency stirring (30-50 rpm);

[0019] b) Second extraction stage: cool to 140±5°C at a rate of 5°C / min and allow to stand for 15-20 minutes;

[0020] Preferred oil: high oleic sunflower oil (oleic acid ≥78%) and cold-pressed sesame oil are mixed in a ratio of 7:3, with an iodine value of 110-125g / 100g.

[0021] Step 4: Physical purification

[0022] Three-stage filtration system:

[0023] a) Primary: 200 mesh stainless steel vibrating screen to remove particles >75 μm;

[0024] b) Secondary: diatomaceous earth plate and frame filtration (precision 10μm);

[0025] c) Third stage: 0.22μm ceramic membrane cross-flow filtration;

[0026] Optimal parameters: filtration temperature is controlled at 45-50℃, system pressure ≤0.3MPa.

[0027] Therefore, the present invention provides a method for preparing "secondary stimulation" chili oil, and its specific technical effects are as follows:

[0028] (1) High-efficiency extraction: Microwave gradient activation increased the cell wall porosity to 82% (SEM analysis), and the capsaicin dissolution rate reached 89.3±0.8%, which was 25.4% higher than that of the traditional process;

[0029] (2) Flavor optimization: The dual-temperature control technology increases the retention rate of the key aroma component 2-methoxy-3-isobutylpyrazine to 92%, and GC-MS detects 43 types of volatile substances;

[0030] (3) Natural stability: The free fatty acid content is reduced to ≤0.15% through a physical purification system, and the peroxide value increase in an accelerated test over 180 days is 53.7% lower than that of the traditional process;

[0031] (4) Energy saving and environmental protection: The production cycle is shortened to 2.5 hours (the traditional process requires 4.5 hours), the unit energy consumption is 0.8kW·h / kg, and energy saving is 38.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 The process flow chart of preparing chili oil by "secondary excitation" provided by the present invention;

[0034] Figure 2 Prepare sensory radar graphs of the effects of different treatment conditions on chili oil on “secondary stimulation”;

[0035] Figure 3 A bar graph was prepared to show the effect of different treatment conditions on the dissolution rate of capsaicin;

[0036] Figure 4 A bar graph was prepared to show the effects of different treatment conditions on the types of aroma components in chili oil. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0038] In order to make the purpose, technical solutions and advantages of the present application clearer, more thorough and more complete, the technical solutions of the present invention are clearly and completely described below through the accompanying drawings and Examples. The following detailed description is an explanation of the embodiments and is intended to provide further details of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the application belongs.

[0039] The present invention provides a method for preparing "secondary excitation" chili oil, which uses a grinder to crush chili to obtain chili powder, and then the crushed chili particles are subjected to three-stage microwave treatment to activate the flavor. Finally, chili oil is obtained by oil phase excitation. The preparation process is as follows Figure 1 shown.

[0040] The "secondary excitation" chili oil preparation process provided by the present invention avoids the problems of low utilization of chili flavor substances and insufficient aroma in traditional chili oil products. By using the secondary excitation method, the flavor substances in the chili peppers are fully extracted into the oil phase, resulting in a more intense flavor of the chili oil.

[0041] The instruments, equipment, reagents and materials used in the examples were obtained from commercial sources.

[0042] Example 1

[0043] Prepare a standard chili oil, the specific steps are as follows:

[0044] Step 1: Accurately weigh 1 kg of Erjingtiao Erjingtiao dried chili peppers (spicy degree 100,000 SHU) and 4.5 kg of mixed oil (sunflower oil: sesame oil = 7:3), and set aside.

[0045] Step 2: Microwave the chili granules using a 750W three-stage irradiation method.

[0046] a) First stage: 700W treatment for 1 minute, the material temperature rises to 60±5℃;

[0047] b) Second stage: 800W for 1.5 minutes, until the core temperature reaches 90±5°C;

[0048] c) The third stage: 600W for 1 minute to soften the cell wall;

[0049] Step 3: Oil phase excitation: 180℃ / 4min→140℃ / 18min

[0050] a) First excitation stage: heat to 180±5°C at a rate of 8-10°C / min, hold for 3-5 minutes, and start variable frequency stirring (30-50 rpm);

[0051] b) Second extraction stage: Cool to 140±5°C at a rate of 5°C / min, and allow to stand for 15-20 minutes;

[0052] Step 4: Filtration temperature: 48°C.

[0053] Example 2

[0054] Prepare a high-flavor chili oil, the specific steps are as follows:

[0055] Step 1: Accurately weigh 1 kg of Erjingtiao Erjingtiao dried chili peppers (spicy degree 100,000 SHU) and 4.5 kg of mixed oil (rice bran oil: camellia oil = 5:5), and set aside.

[0056] Step 2: Microwave the chili granules using a 750W three-stage irradiation method.

[0057] a) First stage: 700W treatment for 1 minute, the material temperature rises to 60±5℃;

[0058] b) Second stage: 800W for 2 minutes, core temperature reaches 90±5℃;

[0059] c) The third stage: 600W for 1 minute to soften the cell wall;

[0060] Step 3: Oil phase excitation: 180℃ / 4min→140℃ / 18min

[0061] a) First excitation stage: heat to 180±5°C at a rate of 8-10°C / min, hold for 5 minutes, and start variable frequency stirring (30-50 rpm);

[0062] b) Second extraction stage: cool down to 140±5°C at a rate of 5°C / min and allow to stand for 15-20 minutes.

[0063] Step 4: Filtration temperature: 48°C

[0064] The present invention also provides the following comparative examples as examples of the effects of the products of the present invention:

[0065] Comparative Example 1

[0066] A chili oil prepared by a traditional hot oil pouring method is prepared.

[0067] (1) Raw material processing: 1 kg of dried chili peppers of Erjingtiao were used as in Example 1, and the stems and impurities were removed and then crushed into 1-3 mm particles;

[0068] (2) Hot oil pouring: Heat 4.5 kg of rapeseed oil to 200 ± 10 ° C, and pour chili powder into it three times:

[0069] a) First time: Pour 30% of the oil into the pan at 200°C and stir for 30 seconds;

[0070] b) Second time: Pour 50% of the oil into the hot oil at 180°C and stir for 2 minutes;

[0071] c) Third time: Pour the remaining 20% of the oil into the 150°C hot oil and let it sit for 10 minutes;

[0072] (3) Filtration: Filter once through a 100-mesh stainless steel sieve.

[0073] Comparative Example 2

[0074] Preparation of chili peppers using a single microwave process

[0075] (1) Raw material processing: using 1 kg of Erjingtiao dried chili peppers as in Example 1;

[0076] (2) Microwave treatment: 800W continuous irradiation for 4 minutes (material temperature reaches 120±5℃);

[0077] (3) Oil phase treatment: 4.5 kg of mixed oil was directly heated to 140 °C and subjected to constant temperature leaching for 30 minutes;

[0078] (4) Filtration: 200 mesh single-stage filtration.

[0079] 50 mL of each chili oil prepared in Example 1-2 and Comparative Example 1-2 was sampled for sensory evaluation using the direct scoring method. The time was set between 10:00 and 15:00, with each sample evaluated once in the morning and once in the afternoon on the same day. For at least 1 hour before the sensory evaluation experiment, sensory evaluators were prohibited from consuming any food or beverage other than purified water. All evaluators scored the various indicators of the solution. Each tasting volume was 2 mL, and after each evaluation, the mouth was rinsed with cold boiled water, with a 60-second interval between evaluations. The sensory evaluation criteria are shown in Table 1.

[0080] Table 1 Sensory standards

[0081]

[0082]

[0083] The results are as follows Figure 2 As shown, Examples 1-2 significantly outperformed Comparative Examples 1-2 in aroma complexity. Comparative Example 1 had a less prominent aroma but no noticeable raw oil flavor. Comparative Example 2 had a noticeable raw oil flavor and lacked flavor. The "secondary stimulation" chili oil prepared in Examples 1-2, on the other hand, enhanced the spiciness and aroma while reducing the raw oil and raw chili flavors.

[0084] Please see the attached Figure 3 1.0 g of chili oil prepared in Example 1-2 and Comparative Example 1-2 was extracted with acetonitrile ultrasonically (40 kHz, 30 min). The extract was then filtered through a 0.22 μm filter membrane with a 10 μl injection volume. The capsaicin content was determined by liquid chromatography (HPLC). Instrument parameters were as follows: Agilent 1260 HPLC system, ZORBAX SB-C18 column (4.6×250 mm, 5 μm), detection wavelength: 280 nm, column temperature: 30°C, flow rate: 1.0 ml / min, mobile phases: A (0.1% formic acid in water), B (acetonitrile), gradient elution program: 0-10 min: Phase B 20%→50%; 10-15 min: Phase B 50%→80%; dihydrocapsaicin and capsaicin were used as standards (Sigma-Aldrich, purity ≥98%).

[0085] from Figure 3As can be seen, due to the extended high temperature period in Example 2, the proportion of cis-capsaicin increased to 34.5% (compared to only 22.2% in Comparative Example 1). The isomer imbalance in Comparative Example 1 resulted in a spicy stimulation index (SI) of 1.8 (compared to 1.2 in Example 1). Implementations 1 and 2 showed even better capsaicin release, with dissolution rates reaching 89.3% and 91.2%, respectively.

[0086] Please see the attached Figure 4 The chili oils prepared in Examples 1-2 and Comparative Examples 1-2 were analyzed for aroma component types. 2.0 g of the chili oils were subjected to solid-phase microextraction (SPME, DVB / CAR / PDMS fiber) using a 60°C equilibration for 15 minutes and adsorption for 30 minutes. GC-MS analysis was performed using an Agilent 7890B gas chromatograph coupled to a 5977B mass spectrometer using a DB-Wax column.

[0087] from Figure 4 It can be seen that the types and quantities of aroma in the chili oil of Examples 1-2 are significantly improved compared with Comparative Examples 1-2, wherein a total of 48 flavor substances were detected in Example 2, a total of 43 flavor substances were detected in Example 1, and 26 and 35 flavor substances were detected in Comparative Examples 1 and 2, respectively. The "secondary excitation" process for preparing chili oil significantly enriches the flavor of chili oil. Among them, the content of 2-methoxy-3-isobutylpyrazine (green pepper aroma), a characteristic flavor component in chili oil, in Example 1 is 28.3 μg / g, while in Comparative Example 1 it is only 9.1 μg / g (a loss of 67.8%). The content of another characteristic flavor component, hexanal (green grass aroma), in Example 2 is 15.6 μg / g (increased by 12% due to the addition of rice bran oil), while in Comparative Example 2 it is 8.7 μg / g (high temperature volatilization). The results showed that the preparation method of "secondary excitation" chili oil uses gradient temperature control to retain low-boiling point aroma components, and the types of aldehyde substances increase by 60% compared with the traditional process, which is conducive to the release and retention of chili flavor substances.

[0088] Therefore, the preparation method of the "secondary stimulation" chili oil provided by the present invention can significantly improve the overall sensory experience of chili oil, increase the dissolution rate of capsaicin, and increase the content and variety of flavor substances. This solves the problem of low utilization of chili flavor substances and insufficient aroma in traditional chili oil products.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing secondary excitation chili oil, characterized in that The following steps are involved: Step 1: Pre-treatment of raw materials: Select dried chili peppers with a moisture content of ≤8%, remove the stems and impurities, and crush them into uniform particles with a particle size of 1-3 mm using a toothed disc crusher. The crushing chamber temperature is controlled at 25±3°C. Step 2: Microwave Activation: Spread the pepper particles on the microwave reactor conveyor belt (the thickness of the material is 2-3 cm) and perform gradient treatment under the conditions of microwave frequency 2450 MHz and power 600-800 W, specifically including: a) First stage: 700W treatment for 1 minute, so that the material temperature reaches 60±5℃; b) Second stage: Adjust the power to 800W for 1-2 minutes, so that the center temperature of the material reaches 90±5℃; c) Stage 3: Reduce power to 600W and maintain for 1 minute to complete cell wall softening; Step 3: Oil phase excitation: Add activated chili granules and edible oil in a weight ratio of 1:3-5 into a double-layer pot, and use a PID temperature control system to perform gradient heating: a) First excitation stage: heat to 180±5°C at a rate of 8-10°C / min and hold for 3-5 minutes, with a variable frequency stirrer (30-50 rpm) running; b) Second extraction stage: Cool to 140±5°C at a rate of 5°C / min, turn off the agitator and extract naturally for 15-20 minutes; Step 4: Standing separation: Transfer the oil mixture to a conical settling tank, first cool it to 60°C at a rate of 2°C / min, and then stand it in a constant temperature environment of 40±2°C for 18-24 hours; Step 5: Precision filtration: Use a three-stage series filtration system: a) Primary filtration: 200-mesh stainless steel vibrating screen to remove large particles of impurities; b) Secondary filtration: diatomaceous earth plate and frame filter (filtration accuracy 10μm); c) Tertiary filtration: 0.22μm ceramic membrane cross-flow filtration.

2. The method according to claim 1, characterized in that Step 2 uses a microwave-hot air combined drying system, and hot air at 50-60° C. (wind speed 1.5 m / s) is introduced simultaneously during microwave treatment, and the relative humidity is controlled at 15-20%.

3. The method according to claim 1, characterized in that In step 3, the edible oil is a mixed oil with an iodine value of 110-125g / 100g, which is compounded by high oleic sunflower oil (oleic acid content ≥78%), cold-pressed sesame oil, and rice bran oil in a volume ratio of 6:3:1.

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