Method for improving aroma of fried rice, fried rice and application

Abstract

This invention provides a method for enhancing the aroma of roasted rice, and the roasted rice and its applications, belonging to the field of traditional food brewing. The method includes the following steps: S1—pretreatment and directed biological fermentation of rice raw materials; S2—segmented precise low-temperature roasting; S3—post-ripening and aging of the roasted rice. By strictly controlling the temperature of the core reaction stage below 180℃, the method of this invention significantly reduces the reaction temperature, thereby increasing product yield and reducing equipment wear and energy consumption. Furthermore, the resulting roasted rice has a more complex aroma profile, a more mellow taste, no burnt, bitter, or astringent flavor, and a reddish-brown color that is more vibrant, bright, translucent, and has strong coloring power. Zhenjiang vinegar produced using the roasted rice prepared by this invention can easily reach or even surpass the standards of top-tier high-end vinegars in terms of flavor complexity, purity, and elegance, providing solid technical support for product differentiation and brand premiumization.

Description

Technical Field

[0001] This invention belongs to the field of traditional food brewing technology, such as vinegar brewing, and specifically relates to a method for enhancing the aroma of fried rice, fried rice, and its application. Background Technology

[0002] Zhenjiang vinegar, a Chinese national geographical indication product, is renowned as the "ultimate vinegar" for its exceptional quality. Its flavor profile can be summarized by five key elements: color, aroma, acidity, mellowness, and richness. Fried rice coloring plays an indispensable role in enhancing both color and aroma. It is not simply a pigment additive, but a functional natural coloring and flavor enhancer that carries complex flavors.

[0003] The roasted rice pigment added during the vinegar-drenching stage, with its caramel coloring and high-molecular-weight brown substances produced by the Maillard reaction, gives Zhenjiang vinegar a deep, clear, and pleasing reddish-brown luster. During processing, the roasted rice pigment produces hundreds of volatile flavor compounds, including pyrazines (nutty and roasted aromas), furans (caramel aromas), sulfur compounds (meat aromas), and aldehydes and ketones. These compounds interact complexly with acids, alcohols, and esters produced during acetic acid fermentation, such as acetic acid, lactic acid, ethanol, ethyl acetate, and ethyl lactate. Together, they construct the rich, mellow, and lingering flavor profile characteristic of Zhenjiang vinegar. Without roasted rice pigment, the flavor of Zhenjiang vinegar would be thin, unbalanced, and lack its essential character.

[0004] Traditional roasted rice preparation essentially relies on a physical process driven by high temperatures, involving Maillard and caramelization reactions. The typical process involves placing dried rice in an iron wok or rotary wok and rapidly stir-frying it at high temperatures (usually 500℃-700℃, or even higher). The rice continuously dehydrates from the heat, changing from white to reddish-yellow, then from yellow to black, until all the black rice grains are bonded together. The starch and other substances within the rice caramelize, forming carbonized melanin. The process continues until the rice grains turn dark brown and develop a rich, roasted aroma.

[0005] Although this process has been used for a long time, its reliance on high-temperature frying has led to a series of inherent defects that are difficult to eradicate, severely hindering the quality improvement of high-end Zhenjiang vinegar: (1) High temperatures inevitably lead to burnt and bitter tastes, a chemical fate that traditional processes cannot overcome. First, there is localized overheating during the roasting process of rice. The temperature at the contact point between the pan and the rice grains is much higher than the average temperature, causing the rice grains in that area to carbonize instantly, generating polycyclic aromatic hydrocarbons such as benzo[a]pyrene and carbonized polymers with a strong burnt smell. Second, the reaction pathway under high temperature conditions is difficult to control. High temperatures accelerate the later stages of the Maillard reaction, especially through pathways such as Streckel degradation, which generate large amounts of pyridine and pyrrole compounds with bitter and burning tastes, as well as certain nitrogen-containing heterocycles. These unpleasant flavor substances have extremely low thresholds. Once generated, even in very small amounts, they are enough to mask or even destroy the main aroma of roasted rice. When roasted rice is added to vinegar, it will give the vinegar a persistent bitter aftertaste.

[0006] (2) The aroma spectrum is simple, lacking in complexity and subtlety. Traditional high-temperature roasting is similar to an "explosive" reaction, which mainly produces primary flavor compounds with fast reaction speed and low formation energy barriers, such as simple methylpyrazine and dimethylpyrazine. However, many more elegant, delicate, and characteristic "high-end" aroma compounds that require medium-low temperature and long-term reaction to form, such as 2-acetyl-1-pyrrolline with the key aroma of popcorn; furanones (such as fenugreek lactone) with strong roasted and coffee aromas; and maltol and its derivatives with creamy and candy aromas, have almost no chance of being formed and accumulated in traditional processes. Therefore, the aroma of traditionally roasted rice is often described as "pungent," "dry," and "bland." Although the aroma is strong, it is not lasting and lacks pleasant and complex changes.

[0007] (3) High-temperature frying poses nutritional losses and potential safety risks. Extreme high temperatures not only destroy the original B vitamins and amino acids in rice, but may also lead to the generation of pollutants such as acrylamide during processing. Although there are currently no clear limits on the content of flaky rice, as a high-end food that pursues health and naturalness, reducing the content of such risky substances is an inevitable trend in the industry's development.

[0008] To address the above problems, the following existing technologies already exist: (1) Improved equipment temperature control method Chinese patent CN215873346U discloses a "novel rice-frying machine," which uses an automatic heating mechanism to heat the wok and a stirring mechanism to stir-fry the rice grains, reducing manual labor and ensuring product stability and quality. This method does improve the uniformity of macroscopic temperature and reduces localized scorching caused by uneven stirring. However, its limitation lies in the fact that it does not change the core premise that "high temperature is the main driving force of the Maillard reaction." As long as the reaction temperature remains high, the chemical pathway for the formation of bitter substances in the later stages of the Maillard reaction cannot be blocked, and the problem of a single aroma remains unresolved. Furthermore, the high investment in equipment also increases production costs.

[0009] (2) Exogenous addition method This involves directly using commercially available caramel coloring and roasted / smoked flavorings for blending. This method can be seen in some low-end products. However, the problem is that it deviates from the core value of traditional brewed condiments—"natural fermentation, original color and aroma"—and is not accepted by consumers and the market. The aroma of artificial flavorings differs fundamentally from that produced by natural fermentation in structure, release curve, and taste. Its flavor is superficial, poorly integrated with vinegar, and has a "fake" taste, lacking the vibrancy and complexity of natural flavors.

[0010] (3) Other methods Chinese patent CN107164208A discloses a "processing technology for a fried rice vinegar flavor," which improves the traditional ingredients and preparation process of fried rice vinegar by adding spices and soy sauce cake to the fried rice vinegar. The frying process is set at three different temperatures: low temperature (120-140℃), medium temperature (140-160℃), and high temperature (160-180℃), resulting in a unique complex flavor (Shanxi smoked vinegar flavor). However, this processing technology introduces soy sauce cake, whose main ingredient is soybeans, along with spices and other substances. The addition of these new ingredients fundamentally deviates from the raw material requirements of Zhenjiang fragrant vinegar fried rice vinegar, compromising the purity of the fried rice vinegar and resulting in low acceptance in practical applications. Furthermore, the differences between the three frying temperatures are small, and due to the large amount of material inside the frying pan, the temperature is difficult to change rapidly during the frying process. Therefore, the actual frying process cannot be carried out according to the theoretical frying temperature.

[0011] In summary, existing technologies have failed to fundamentally resolve the contradiction between "high temperature" and "good flavor" in the traditional preparation of roasted rice starch. There is an urgent need in this field for a novel, fundamentally innovative method for preparing roasted rice starch that can break this technological deadlock. Summary of the Invention

[0012] In view of the problems existing in the traditional preparation process of fried rice sauce, this application proposes a method for improving the aroma of fried rice sauce, fried rice sauce, and its application.

[0013] In a first aspect, this application provides a method for enhancing the aroma of roasted rice, comprising the following steps: S1—Pretreatment and Directed Bio-fermentation of Rice Raw Materials S1-1 Raw material selection and proportioning: Select rice harvested in the current year with moderate amylose content and high protein content; S1-2 Cleaning and Soaking: Use running water to clean the surface to remove dust and impurities, then soak. S1-3 Steaming: Use normal or pressurized steam to steam the rice until it is "hard on the outside and soft on the inside, cooked but not mushy, thoroughly cooked but not mushy, and without a white core"; S1-4 Cooling and Inoculation: Quickly cool the cooked rice to 30-40℃; activate and expand the compound microbial strains separately, and spray the bacterial solution directly onto the surface of the rice. The total inoculation amount is 0.5‰-2.0‰ of the dry weight of the rice. S1-5 Temperature-Controlled Solid-State Fermentation: Spread the inoculated rice to a thickness of 5-10cm, maintain a temperature of 28-37℃ and a relative humidity of 85%-95%, and ferment at a constant temperature for 24-36 hours. S2—Segmented Precision Low-Temperature Stir-Frying S2-1 Dehydration stage of Miqu; S2-2 Mid-temperature aroma enhancement stage; S2-3 Cooling and fragrance-locking stage; S3—Post-fermentation and aging of beige.

[0014] Preferably, S2—segmented precision low-temperature stir-frying—specifically refers to: S2-1: Dehydration stage of koji Preheat the wok to 90℃, add an appropriate amount of fermented rice koji, stir-fry evenly, and gently remove free moisture. S2-2: Mid-temperature aroma enhancement stage Raise the pan temperature steadily and slowly to about 170℃, and stir-fry continuously at this temperature for 40-60 minutes; S2-3: Cooling and Fragrance Locking Stage When the fried rice reaches the ideal reddish-brown color, immediately stop heating and quickly cool the material. When the temperature drops below 100℃, add water and stir to dissolve the fried rice, allowing its temperature to drop below 80℃ in a short time.

[0015] More preferably, the ideal reddish-brown color is determined by colorimetric comparison with a colorimeter or with a standard sample.

[0016] Preferably, the post-fermentation and aging of S3—fried rice paste is specifically as follows: the fried rice paste is placed in a sealed, light-proof container and aged for 7-15 days in a cool, dry, and ventilated environment.

[0017] Preferably, the composite microbial strains used in the cooling and inoculation of S1-4 are Aspergillus oryzae, Aspergillus soysarum, Candida tropicalis, and Bacillus belesiensis.

[0018] More preferably, *Aspergillus oryzae* is deposited at the China General Microbiological Culture Collection Center (CGMCC) under accession number CCTCC NM:M 20221829 on November 28, 2022; *Aspergillus soysarum* is deposited at the China General Microbiological Culture Collection Center (CGMCC) under accession number CGMCC NO.41133 on April 1, 2024; *Candida tropicalis* is deposited at the China General Microbiological Culture Collection Center (CGMCC) under accession number CCTCC NO:M 20221651 on October 25, 2022; and *Bacillus belyssus* is deposited at the China General Microbiological Culture Collection Center (CGMCC) under accession number CGMCC NO.20063 on June 10, 2020.

[0019] Preferably, the rice in the raw material selection and proportioning of S1-1 is japonica rice or glutinous rice, or a mixture of japonica rice and glutinous rice in a mass ratio of 7:3.

[0020] More preferably, the soaking conditions in S1-2 washing and soaking are: soaking in water at 25-30℃ for 2-4 hours until the moisture content of the rice grains reaches 30%-35%; and the moisture content of the cooked rice in S1-3 steaming is 40%-45%.

[0021] Secondly, this application provides a roasted rice coloring, which is prepared by the above-mentioned method for enhancing the aroma of roasted rice coloring.

[0022] Thirdly, this application provides an application of roasted rice coloring in vinegar brewing process.

[0023] Preferably, the vinegar is Zhenjiang vinegar or Yongchun aged vinegar.

[0024] Beneficial effects: 1. The method of this invention strictly controls the temperature of the core reaction stage below 180℃. Compared with the existing roasting temperature of roasted beige (500-700℃), the reaction temperature is reduced by 300-500℃, resulting in a significant reduction in energy consumption and equipment wear. In terms of product yield, this invention avoids high-temperature carbonization losses, and effectively increases the yield of roasted beige by 10%-15% under the same feed amount. In terms of safety indicators, it can theoretically significantly reduce the risk of generating high-temperature processing pollutants such as acrylamide and benzo[a]pyrene.

[0025] 2. The roasted rice color obtained by the method of this invention achieves excellent results in terms of aroma, taste, and color. In terms of aroma, it has a complex aroma profile; typical characteristics include: a strong roasted rice nutty aroma as the main component, with a clear caramel sweetness, a light creamy aroma, a subtle wine aroma, and ester fruit aroma in the background; the aroma is rich and long-lasting, and when added to vinegar, the flavor is released layer by layer in the mouth, with a long aftertaste and no harshness or dullness. In terms of taste, it has no burnt taste, no bitterness, and no astringency; its own taste is mellow, slightly sweet with a hint of caramel, and it blends perfectly with vinegar, significantly enhancing the fullness and richness of Zhenjiang vinegar. In terms of color, the obtained roasted rice color is reddish-brown, bright, and lustrous, with good light transmittance, strong and stable coloring power.

[0026] 3. The method of the present invention does not add any foreign raw materials, chemical pigments, or flavorings throughout the entire process. All flavors and colors come from the biotransformation and thermal reaction of natural raw materials, which is in line with the trend of clean labeling.

[0027] 4. The Zhenjiang vinegar produced using the fried rice color prepared by this invention can easily reach or even surpass the standards of top-grade high-end vinegar in terms of flavor complexity, purity, and elegance, providing solid technical support for product differentiation and brand premiumization. Attached Figure Description

[0028] Figure 1 A schematic diagram comparing the temperature-time curves of the traditional high-temperature frying process and the segmented low-temperature frying process of the present invention. Figure 2 This is a radar comparison image of the electronic nose flavor profile of traditional fried rice and the fried rice of this invention. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, but the embodiments of the present invention are not limited thereto. Those skilled in the art should understand that modifications and adjustments can be made to the embodiments without departing from the spirit and scope of the present invention, and such modifications and adjustments all fall within the scope covered by the claims of the present invention.

[0030] Example 1: Preparation of fried rice paste under standard process parameters, the resulting fried rice paste product is denoted as sample A.

[0031] S1: Bio-fermentation stage Raw material processing: Take 50kg of japonica rice, wash until the water is clear, soak in 30℃ warm water for 3 hours, drain and drain. The water content of the rice after soaking is 33%. Steaming: Place the soaked rice in a steamer and steam under normal pressure for 30 minutes, until the rice grains are fully cooked and there is no white center. The moisture content of the steamed rice is 42%. Cooling inoculation: Quickly cool the steamed rice to 37℃, then inoculate with a compound microbial strain at 1.0‰ of the dry weight of the rice. The compound microbial strain ratio is: *Aspergillus oryzae* CCTCC NM:M 20221829 (60%), *Aspergillus soysarum* CGMCC NO.41133 (20%), *Bacillus belyi* CGMCC NO.20063 (10%), and *Candida tropicalis* CCTCC NO:M 20221651 (10%). The activation and propagation of the above strains, as well as the preparation of the seed culture, are all done using conventional methods; a mixed inoculation of multiple strains is used, and uniform inoculation is strived for.

[0032] Temperature-controlled fermentation: Spread the inoculated rice onto a sterile fermentation tray to a thickness of 8cm. Place it in a temperature- and humidity-controlled incubation room, setting the temperature to 32℃ and the relative humidity to 90%, for 36 hours of fermentation. During this period, turn the rice koji for the first time at 12 hours and for the second time at 24 hours to ensure even aeration. After fermentation, the rice koji will be slightly yellowish-green, with relatively dense mycelium, and will have a rich aroma of koji and sweet wine.

[0033] S2: Segmented Precision Low-Temperature Stir-Frying This stage uses an intelligent temperature-controlled electromagnetic stir-frying machine for stir-frying.

[0034] Dehydration stage of rice koji: Preheat the wok to 90℃, add all the fermented rice koji, and stir-fry at a constant speed of 40 rpm. This stage lasts for 20 minutes. Observe that a large amount of steam escapes from the wok, and the rice koji changes from moist and sticky to loose and dry, with the moisture content dropping to 18%. At this time, the color of the rice koji darkens slightly, turning light yellow.

[0035] Medium-temperature aroma enhancement stage: Slowly raise the pan temperature to 170℃ at a rate of 2.5℃ / min (heating time is 30min). Maintain this temperature and continue stir-frying for 50 minutes. During this process, the color of the rice koji can be clearly observed to gradually change from light yellow to golden yellow, dark yellow, light brown, and finally to reddish brown. At the same time, the aroma gradually intensifies, evolving from the initial grain and koji aromas to a strong nutty and roasted aroma, accompanied by a sweet caramel and creamy aroma. No irritating burnt smoke is produced throughout the entire stir-frying process.

[0036] Cooling and aroma-locking stage: When the rice koji reaches the target reddish-brown color, immediately stop heating, turn on the wok cooling system and supplement with cold air blowing, and when the temperature drops below 100℃, add water and stir, reducing the material temperature to about 50℃ within 10 minutes. Remove from the wok to obtain the fried rice-colored product of this invention, denoted as sample A.

[0037] S3: Post-fermentation and aging of beige The stir-fried beige sample A was placed in a post-fermentation tank and stored in a cool, dry, and ventilated environment for 10 days to complete the post-fermentation and aging process.

[0038] Example 2: Preparation of fried rice bran with adjusted fermentation strain ratio, the resulting fried rice bran product is designated as sample B.

[0039] This embodiment aims to explore the effect of microbial strain ratio on flavor. The steps are basically the same as in Example 1, except that the ratio of compound microbial strains in step S1 is changed.

[0040] The strain ratio is as follows: Aspergillus oryzae CCTCC NM:M 20221829 (50%), Aspergillus oryzae CGMCC NO.41133 (40%), Candida tropicalis CCTCC NO:M 20221651 (10%), and Bacillus vesiculosus CGMCC NO.20063 is not added.

[0041] Biological fermentation stage: Same as in Example 1. After fermentation, the aroma of the rice koji is more prominent.

[0042] Segmented precise low-temperature stir-frying: Same as Example 1.

[0043] Post-fermentation and aging of fried rice: Same as in Example 1.

[0044] Example 3: Preparation of fried rice color by adjusting the frying temperature, the resulting fried rice color product is denoted as sample C.

[0045] This embodiment aims to explore the influence of core frying temperature. The steps are basically the same as in Example 1, except that the frying temperature during the medium-temperature aroma enhancement stage is changed.

[0046] Bio-fermentation stage: Same as in Example 1.

[0047] Segmented, precise low-temperature stir-frying: Dehydration stage of rice koji: Same as in Example 1.

[0048] Medium-temperature aroma enhancement stage: Raise the pan temperature to 150°C and maintain this temperature while stir-frying for 60 minutes until a reddish-brown color similar to that in Example 1 is achieved.

[0049] Cooling and fragrance-locking stage: Same as in Example 1.

[0050] Post-fermentation and aging of fried rice: Same as in Example 1.

[0051] Example 4: Preparation of fried rice color by adjusting the frying temperature, the resulting fried rice color product is denoted as sample D.

[0052] This embodiment aims to explore the effects of higher frying temperatures (but still within the scope of this invention).

[0053] Bio-fermentation stage: Same as in Example 1.

[0054] Segmented, precise low-temperature stir-frying: Dehydration stage of rice koji: Same as in Example 1.

[0055] Medium-temperature aroma enhancement stage: Raise the pan temperature to 180°C and maintain this temperature while stir-frying for 35 minutes until a reddish-brown color similar to that in Example 1 is achieved.

[0056] Cooling and fragrance-locking stage: Same as in Example 1.

[0057] Post-fermentation and aging of fried rice: Same as in Example 1.

[0058] Comparative Example 1: The traditional high-temperature frying process resulted in a beige-colored fried product, denoted as Sample E.

[0059] Take 50 kg of japonica rice from the same batch as in Example 1, without fermentation. The dried raw rice is directly put into a wok preheated to 600°C. It is stir-fried according to the process requirements, during which a large amount of smoke is visible, accompanied by a slightly pungent odor. The rice is continuously heated and dehydrated, changing from white to reddish-yellow, then from yellow to black, until all the black rice grains are joined together. Heating is stopped immediately and the temperature is lowered. When the temperature drops below 100°C, the rice is removed from the wok, water is added and stirred, resulting in the traditional fried rice color, denoted as Sample E.

[0060] Comparative Example 2: Only biological fermentation without frying, the resulting fried beige product is denoted as Sample F.

[0061] The biological fermentation steps are exactly the same as in Example 1, resulting in fermented rice koji.

[0062] Without frying, the fermented rice koji is directly dried in a forced-air dryer at 60℃ until the moisture content is less than 10%.

[0063] The dried fermented rice koji was obtained and denoted as sample F.

[0064] Comparative Example 3: The product obtained by the process of first frying and then fermenting is designated as sample G.

[0065] First, stir-fry: refer to the traditional process of Comparative Example 1, but reduce the degree of stir-frying. Stir-fry until the rice grains just turn light yellow and then remove from the pan to obtain lightly stir-fried rice.

[0066] Post-fermentation: The lightly roasted rice was cooled to 37°C. Since the rice grains were dry and hard after roasting, a suitable amount of sterile water was sprayed to restore the moisture content to 40%. Then, the same compound microbial strain as in Example 1 was inoculated (inoculation amount 1.0‰). Fermentation was carried out at 32°C and 90% humidity for 36 hours. Observation revealed extremely weak microbial growth; only scattered bacterial spots were observed on the surface of the rice grains, and uniform mycelium could not form. Fermentation was terminated, and the material was dried at 60°C. The resulting product was designated as sample G.

[0067] Comparative Example 4: Low-temperature roasting of unfermented rice, the resulting roasted rice product is denoted as Sample H.

[0068] Take 50 kg of japonica rice from the same batch as in Example 1, and without fermentation, directly perform segmented, precise, low-temperature roasting: Dehydration stage of japonica rice: Since it is raw rice with low moisture content, the main purpose of this stage is preheating, stir-frying at 90℃ for 10 minutes.

[0069] Medium-temperature aroma enhancement stage: The temperature was raised to 170℃ and maintained at this temperature while stir-frying for 50 minutes. Observation revealed that the color change of the rice grains was extremely slow; after 50 minutes, they only turned light yellow, far from reaching reddish-brown. The aroma was also very weak, mainly a slight roasted grain scent. The resulting product is designated as sample H.

[0070] Results and Analysis Various indicators were tested and evaluated on samples A, B, C, and D of the embodiments of the present invention, as well as comparative samples E, F, G, and H.

[0071] 1. Color analysis of the beige sample The above-mentioned roasted beige samples were centrifuged at 5000 rpm for 15 minutes. The upper portion of the roasted beige liquid was collected and diluted 50 times to obtain a diluted roasted beige solution. The colorimetric properties of each sample were measured using a colorimeter. Value, and calculate The ratios are shown in Table 1.

[0072] Table 1. Color Measurement Results of Each Sample

[0073] As can be seen from Table 1, all samples (AD) of the embodiments of the present invention achieved ideal low brightness ( Low value) and high reddish-brown color ( >0.72), with a deep and bright color. Comparative Example E (traditional stir-frying process), although... It's acceptable, but its The lowest value indicates that its color is too dark, almost black, which is consistent with the small number of carbonization points actually observed. Comparative examples F, G, and H... The value is far lower than that of this invention, and the color is pale, which does not meet the color requirements of fried rice at all.

[0074] Sensory evaluators, five men and five women, with at least two years of experience in condiment sensory evaluation, were assembled to conduct sensory evaluations of each sample. Quantitative descriptive analysis was used. The diluted roasted rice color solution was placed in evaluation cups, sealed, and equilibrated in a 25°C water bath for 30 minutes. Evaluators evaluated independently, and the final score was the average of the scores given by the ten evaluators. Evaluation indicators and scales are shown in Table 2, and sensory evaluation scores are shown in Table 3.

[0075] Table 2 Evaluation Indicators and Scales for Each Sample

[0076] Table 3 Sensory evaluation scores for each sample (0-10 points)

[0077] *Note: The off-odor of sample G is not a typical burnt smell, but an off-odor caused by incomplete fermentation, which is a mixture of moldy and slightly roasted smells.

[0078] The samples (AD) of this invention scored extremely low (all <1) in terms of burnt / bitterness intensity, significantly better than comparative example E (4.5 points), proving that this invention completely eliminates unpleasant flavors. In terms of aroma intensity and complexity, the samples of this invention scored far higher than all comparative examples. In particular, in terms of aroma complexity, the samples of this invention all scored above 8.5, while comparative example E only scored 5.5, and comparative examples F, G, and H scored even lower. This confirms that the synergistic effect of bio-fermentation and segmented roasting produced a richer and more complex aroma.

[0079] Ultimately, the overall pleasure score of the samples from this invention (8.7-9.2) was far higher than that of traditional processes (4.0) and other comparative examples (2.5-5.5), demonstrating its absolute advantage in overall sensory quality.

[0080] Accurately weigh 1.0 g of roasted beige sample and place it in a 20 ml headspace vial for enrichment using headspace solid-phase microextraction. GC-MS conditions were as follows: DB-WAX column (60 m × 0.25 mm × 0.25 μm); injection port temperature 250℃; split ratio 10:1; temperature program: 40℃ for 3 min, increased to 100℃ at 5℃ / min, then increased to 230℃ at 10℃ / min and held for 10 min; ion source temperature 230℃; transfer line temperature 250℃; scan range m / z 35-350. Qualitative analysis was performed using the NIST standard spectral library, and semi-quantitative analysis was performed using area normalization.

[0081] Semi-quantitative analysis was performed on sample A of preferred embodiment 1, sample E of comparative example 5 (traditional fermentation process), and sample F of comparative example 6 (fermentation process only) in the above embodiments, focusing on the relative content (expressed as percentage of total peak area %) of several key flavor substances. The results are shown in Table 4.

[0082] Table 4. Comparison of relative contents of key flavor compounds by GC-MS (%)

[0083] As shown in Table 4, Sample A not only contains abundant conventional pyrazines and furans, but also significantly enriches 2-acetylpyrazine (a key aroma in popcorn) and furanones (fenugreek lactone and methylcyclopentenolone, providing strong caramel sweetness and nutty aroma). These substances form the chemical basis for the complex, elegant, and characteristic aroma of the samples in this invention. Simultaneously, Sample A also retains a considerable proportion of esters and higher alcohols produced during fermentation, contributing to the underlying fruity and floral notes.

[0084] In Comparative Example E, although the content of conventional pyrazines and furfural was relatively high, the content of high-value flavor compounds such as 2-acetylpyrazines and furanones was extremely low. More importantly, it produced a large amount of pyridines and phenols, which are the direct causes of its burnt, bitter, and smoky flavors. Comparative Example F completely lacked the characteristic roasting aroma compounds produced by the Maillard reaction (pyrazines, furans, and furanones were all 0 or very low), and only contained esters and alcohols produced by fermentation, resulting in a single flavor profile.

[0085] To verify the performance of the fried rice starch prepared by the present invention in practical applications, the fried rice starch samples obtained in the above examples and comparative examples were added to the same batch of base vinegar in the same proportion for sensory evaluation of the vinegar.

[0086] The base vinegar (acidity 5.0 g / 100 mL) was taken from the same production batch, completed acetic acid fermentation, and without leaching or blending. This base vinegar has a pure flavor, free of off-flavors, and can best reflect the differences brought about by different roasted rice colors. 50 g of each roasted rice color sample (dry basis) was accurately weighed and mixed with 1000 mL of base vinegar. After thorough stirring, the mixture was allowed to stand at room temperature for 48 hours to obtain the vinegar samples to be evaluated. These samples were labeled as vinegar samples A, B, C, D, E, F, G, and H, respectively. A separate sample of base vinegar without any added roasted rice color was taken as a blank control and labeled as vinegar sample CK.

[0087] The sensory evaluation panel, along with the aforementioned 10-person professional sensory evaluation panel, used a blind evaluation method, randomly numbering the vinegar samples and placing them in identical tasting cups. The evaluators conducted quantitative descriptive analysis and scoring based on the vinegar flavor evaluation indicators and scales in Table 5. The final score was the average of the scores given by the 10 evaluators. The sensory evaluation scores for the vinegar are shown in Table 6.

[0088] Table 5. Evaluation Indicators and Scales for Vinegar Flavor

[0089] Table 6 Sensory evaluation scores of each vinegar sample (0-10 points)

Claims

1. A method for enhancing the color and aroma of fried rice, characterized in that, Includes the following steps: S1—Pretreatment and Directed Bio-fermentation of Rice Raw Materials S1-1 Raw material selection and proportioning: Select rice harvested in the current year with moderate amylose content and high protein content; S1-2 Cleaning and Soaking: Use running water to clean the surface to remove dust and impurities, then soak. S1-3 Steaming: Use normal or pressurized steam to steam the rice until it is "firm on the outside and soft on the inside, cooked but not mushy, thoroughly cooked but not mushy, and without a white core"; S1-4 Cooling and Inoculation: Quickly cool the cooked rice to 30-40℃; activate and expand the compound microbial strains separately, and spray the bacterial solution directly onto the surface of the rice. The total inoculation amount is 0.5‰-2.0‰ of the dry weight of the rice. S1-5 Temperature-Controlled Solid-State Fermentation: Spread the inoculated rice to a thickness of 5-10cm, maintain a temperature of 28-37℃ and a relative humidity of 85%-95%, and ferment at a constant temperature for 24-36 hours. S2—Segmented Precision Low-Temperature Stir-Frying S2-1 Dehydration stage of Miqu; S2-2 Mid-temperature aroma enhancement stage; S2-3 Cooling and fragrance-locking stage; S3—Post-fermentation and aging of beige.

2. The method for enhancing the color and aroma of fried rice according to claim 1, characterized in that, The S2-segmented precise low-temperature stir-frying process specifically refers to: S2-1: Dehydration stage of koji Preheat the wok to 90℃, add an appropriate amount of fermented rice koji, stir-fry evenly, and gently remove free moisture. S2-2: Mid-temperature aroma enhancement stage Raise the pan temperature steadily and slowly to about 170℃, and stir-fry continuously at this temperature for 40-60 minutes; S2-3: Cooling and Fragrance Locking Stage When the fried rice reaches the ideal reddish-brown color, immediately stop heating and quickly cool the material. When the temperature drops below 100℃, add water and stir to dissolve the fried rice, allowing its temperature to drop below 80℃ in a short time.

3. The method for enhancing the color and aroma of fried rice according to claim 2, characterized in that, The ideal reddish-brown color is determined by colorimetric comparison with a colorimeter or with a standard sample.

4. The method for enhancing the color and aroma of fried rice according to claim 1, characterized in that, The post-fermentation and aging of S3-fried rice paste specifically involves placing the fried rice paste in a sealed, light-proof container and aging it for 7-15 days in a cool, dry, and ventilated environment.

5. The method for enhancing the color and aroma of fried rice according to claim 1, characterized in that, The composite microbial strains used in the S1-4 cooling and inoculation process are Aspergillus oryzae, Aspergillus soysarum, Candida tropicalis, and Bacillus belesiensis.

6. The method for enhancing the color and aroma of fried rice according to claim 5, characterized in that, The Aspergillus oryzae mentioned is: WJM-008, deposited at the China Center for Type Culture Collection, with accession number CCTCC NM:M 20221829, and deposit date November 28, 2022; The Aspergillus oryzae mentioned is HSCY-6012, deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC NO.41133 and deposit date of April 1, 2024. The tropical Candida species is CS-8, deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M20221651 and deposit date of October 25, 2022. The Bacillus belyssus is HSYB-011, deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC NO.20063 and deposit date of June 10, 2020.

7. The method for enhancing the aroma and color of fried rice according to claim 1, characterized in that, The rice in the raw material selection and proportioning of S1-1 is japonica rice or glutinous rice, or a mixture of japonica rice and glutinous rice in a mass ratio of 7:

3.

8. The method for enhancing the color and aroma of fried rice according to claim 1, characterized in that, The soaking conditions in S1-2 washing and soaking are: soaking in water at 25-30℃ for 2-4 hours until the moisture content of the rice grains reaches 30%-35%; the moisture content of the cooked rice in S1-3 steaming is 40%-45%.

9. A type of fried beige, characterized in that, It is prepared by the method for enhancing the color and aroma of fried rice as described in any one of claims 1-8.

10. The application of the fried rice color as described in claim 9 in the vinegar brewing process.

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