Fermented orange juice and method for preparing the same

Abstract

The application provides a fermented orange juice and a preparation method thereof, and belongs to the technical field of food processing. The method first prepares orange peel extract liquid, and then prepares base liquid by blending the orange peel extract liquid with concentrated orange juice. After sterilization, the base liquid is inoculated with plant lactobacillus and paracasei to perform segmented fermentation. When the pH of the fermentation liquid decreases to 4.3+ / -0.1, orange oil is added to continue fermentation. After fermentation, the product is obtained through secondary sterilization. The application can enrich the flavor level of the fermented orange juice, improve the comprehensive utilization rate of orange raw materials, weaken the bitter taste of the product, effectively relieve the antibacterial effect of orange oil on lactic acid bacteria, shorten the fermentation period, improve the production efficiency, and has good product system stability, which is suitable for industrial large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, and specifically relates to a fermented orange juice and its preparation method. Background Technology

[0002] Orange juice, with its sweet and sour taste and rich content of vitamins and minerals, is one of the mainstream categories in the fruit and vegetable juice market. Lactic acid bacteria fermentation of orange juice transforms the sugars and organic acids in the juice through microbial metabolism, giving the product a unique fermented flavor and probiotic properties, and has received widespread market attention in recent years.

[0003] The current standard process for preparing fermented orange juice in the industry is as follows: using concentrated orange juice or freshly squeezed orange juice as raw material, water is added to adjust the soluble solids to a suitable range, the pH is adjusted with alkaline substances, sterilization is performed, and then lactic acid bacteria are inoculated for constant-temperature fermentation; after fermentation reaches the target indicators, a second sterilization and bottling are performed to obtain the finished product. This process is simple and has a low technical threshold, making it the mainstream technology solution for fermented orange juice production.

[0004] However, existing technologies still have many technical shortcomings that are difficult to address in practical applications:

[0005] Firstly, the product has a monotonous flavor and insufficient aroma complexity. The existing process uses only the orange pulp as the fermentation substrate. The lactic acid bacteria can only utilize the sugars and acids in the juice to generate fermented flavor substances, and cannot utilize the characteristic aroma components such as terpenes, aldehydes, esters, and alcohols contained in orange peel and orange oil. The finished product aroma is mainly a single fermented sour aroma, lacking the complexity and richness of natural orange aroma, resulting in serious homogenization of product flavor.

[0006] Secondly, the utilization rate of orange raw materials is low, and the waste of by-product resources is serious. The orange juice processing process generates a large amount of by-products such as orange peels. The existing fermentation technology only utilizes the pulp juice, and the orange peels and other by-products are mostly treated as waste materials, failing to achieve high-value utilization. This not only increases the overall cost of raw materials, but also increases the environmental pressure of by-product treatment.

[0007] Third, the lack of effective control over bitter substances results in poor palatability of the finished product. Orange juice itself contains natural bitter substances such as naringin and limonene. Current processes mostly use single common lactic acid bacteria for fermentation, which has little impact on bitter substances. However, the heating process in the process can exacerbate the formation of bitter substances, making the fermented product prone to leaving a noticeable bitter taste, which negatively affects the overall flavor of the product and reduces consumer acceptance.

[0008] Therefore, developing a fermented orange juice preparation method that combines high flavor richness, high raw material utilization, weak bitterness, and excellent fermentation efficiency is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] To address the problems existing in the prior art, the purpose of this invention is to overcome the shortcomings of existing fermented orange juice preparation technologies, such as monotonous flavor, low utilization rate of orange raw materials, obvious bitterness in the finished product, and the tendency of adding orange oil in advance to inhibit lactic acid bacteria activity, prolong the fermentation cycle, and reduce production efficiency. This invention provides a fermented orange juice and its preparation method, which utilizes orange peel by-products, employs dual-strain fermentation, and adds orange oil during the fermentation process to enrich the flavor layers of the fermented orange juice, improve the comprehensive utilization rate of oranges, weaken the bitterness of the product, effectively alleviate the antibacterial effect of orange oil, shorten the fermentation cycle, improve fermentation efficiency, and balance product flavor quality with industrial production benefits.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] The first aspect of the present invention provides a method for preparing fermented orange juice, comprising the steps of preparing orange juice base liquid, sterilization, inoculation with lactic acid bacteria for fermentation, and post-fermentation sterilization, specifically including the following steps:

[0012] Step 1, Preparation of orange peel extract: Mix dried orange peel with water, heat and extract, filter and collect the filtrate to obtain orange peel extract;

[0013] Step 2, base solution preparation: Mix the concentrated orange juice with the orange peel extract described in Step 1, add water to adjust the soluble solids content of the system to 19.0±0.5%, and then adjust the pH of the system to 4.5±0.1 to obtain the prepared base solution;

[0014] Step 3, First sterilization treatment: After filtering the prepared base solution, it is preheated, degassed, homogenized and then subjected to ultra-high temperature instantaneous sterilization.

[0015] Step 4, Segmented Fermentation: Cool the sterilized base liquid to 36~38℃, inoculate with *Lactobacillus plantarum* and *Lactobacillus paracasei*, and carry out the first stage of fermentation under constant temperature conditions; when the pH of the fermentation liquid drops to 4.3±0.1, add orange oil to the fermentation liquid and continue the second stage of fermentation until the soluble solids content of the fermentation liquid is 18±1.5% and the pH is 3.9±0.15, and the fermentation is completed to obtain the fermentation stock liquid;

[0016] Step 5, Second sterilization treatment: After filtering the fermentation liquid, it is preheated, degassed, and homogenized in sequence, and then subjected to ultra-high temperature instantaneous sterilization to obtain the fermented orange juice product.

[0017] Furthermore, in step 1, the mass ratio of dried orange peel to water is 1:30~40, the extraction temperature is 85~95℃, and the extraction time is 5~20 minutes.

[0018] Furthermore, in step 2, based on the total mass of the final prepared base liquid, the amount of concentrated orange juice added is 250~350 g / kg; the orange peel extract is added according to the mass of dried orange peel, and the amount added based on dried orange peel is 10~20 g / kg, and the remaining amount of the prepared base liquid is made up by water.

[0019] Furthermore, in step 2, the pH of the system is adjusted using a 20% potassium hydroxide solution.

[0020] Furthermore, in steps 3 and 5, the preheating temperature is 60~70℃, the degassing vacuum degree is -0.06 ~ -0.07MPa, the homogenization pressure is 10~20 MPa, and the homogenizer operating frequency is 40~45 Hz; the ultra-high temperature instantaneous sterilization process conditions are a temperature of 115±0.5℃ and a holding time of 15 seconds.

[0021] Furthermore, in step 4, based on the mass of the sterilized base liquid, the inoculation amounts of *Lactobacillus plantarum* and *Lactobacillus paracasei* are both... ~ CFU / g.

[0022] Furthermore, the *Lactobacillus plantarum* is Chr. Hansen's Harvest LB-1 strain, and the *Lactobacillus paracasei* is Chr. Hansen's L. casei-01 strain.

[0023] Furthermore, in step 4, the amount of orange oil added is 0.2~1.0 g / kg, based on the total mass of the fermentation liquid at the end of the first stage of fermentation.

[0024] Furthermore, in step 4, the constant temperature fermentation temperature is 37℃, and the total fermentation time is 24~72 hours.

[0025] A second aspect of the present invention provides a fermented orange juice prepared by the method described in the first aspect.

[0026] The advantages of this invention compared to the prior art are as follows:

[0027] 1. Rich flavor and high raw material utilization: By blending orange peel extract and supplementing orange oil during the fermentation process, characteristic flavor substances such as terpenes and aldehydes in orange peel and orange oil are introduced into the fermentation system. These substances are synergistically integrated with the fermentation aroma produced by lactic acid bacteria metabolism, significantly improving the flavor layers and aroma coordination of fermented orange juice. At the same time, it realizes the high-value utilization of orange processing by-products and improves the comprehensive utilization rate of orange raw materials.

[0028] 2. Reduced bitterness and improved palatability: The product is fermented with a combination of Lactobacillus plantarum and Lactobacillus paracasei. The metabolism of the two bacteria can transform and degrade the bitter substances in the orange juice and peel, effectively reducing the bitterness of the finished product and making the product sweet and sour with a prominent fruit flavor.

[0029] 3. Highly efficient fermentation, suitable for industrial production: The process of adding orange oil in the middle of fermentation is adopted. Orange oil is introduced after the lactic acid bacteria enter the stage of vigorous metabolism. This not only retains the aroma-enhancing effect of orange oil, but also effectively alleviates the inhibitory effect of orange oil on the growth of lactic acid bacteria, significantly shortens the fermentation cycle, improves production efficiency, and reduces production energy consumption and time costs.

[0030] 4. Stable system and excellent appearance quality: Adding orange oil during the fermentation stage allows it to be fully mixed and integrated with the fermentation liquid, avoiding the problems of floating oil and layering that are easy to occur when adding it after fermentation. The product system is uniform and stable, and the appearance quality is better. Detailed Implementation

[0031] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to exemplify and further explain and illustrate the content of the present invention, and are not intended to limit the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing fermented orange juice, including the steps of preparing orange juice base liquid, sterilization, inoculation with lactic acid bacteria for fermentation, and post-fermentation sterilization. The specific method is as follows:

[0036] Step 1, Preparation of orange peel extract: Mix dried orange peel with water at a ratio of 1:35, heat to 90℃ for 10 min for extraction, filter through a 200-mesh filter to obtain the filtrate, and allow it to cool naturally to obtain the orange peel extract.

[0037] Step 2, base solution preparation: Mix the concentrated orange juice with the orange peel extract described in Step 1. Based on the total mass of the final base solution, the amount of concentrated orange juice added is 300 g / kg, and the amount of orange peel extract added is calculated based on the mass of dried orange peel, which is 15 g / kg. Add water to adjust the soluble solids content of the system to 19.0±0.5%, then prepare a 20% potassium hydroxide solution and adjust the pH of the system to 4.5±0.1 to obtain the base solution.

[0038] Step 3, First sterilization treatment: After passing the prepared base solution through an 80-mesh sieve, it is preheated, degassed, homogenized, and then subjected to ultra-high temperature instantaneous sterilization. The preheating temperature is 60~70℃, the degassed vacuum degree is -0.06 ~ -0.07MPa, the homogenization pressure is 10~20 MPa, and the homogenizer operating frequency is 40~45 Hz; the ultra-high temperature instantaneous sterilization process conditions are a temperature of 115±0.5℃ and a holding time of 15 seconds.

[0039] Step 4, Segmented Fermentation: Cool the sterilized base liquid to 37°C, inoculate with *Lactobacillus plantarum* and *Lactobacillus paracasei*, and carry out the first stage of fermentation under constant temperature conditions; when the pH of the fermentation liquid drops to 4.3±0.1, add orange oil to the fermentation liquid and continue the second stage of fermentation until the soluble solids content of the fermentation liquid is 18±1.5% and the pH is 3.9±0.15, and the fermentation is completed to obtain the fermentation stock liquid.

[0040] The *Lactobacillus plantarum* strain was Chr. Hansen's Harvest LB-1, and the *Lactobacillus paracasei* strain was Chr. Hansen's L. casei-01. The inoculation amount for both strains was [missing information]. ~ CFU / g. The amount of orange oil added is 0.5 g / kg, based on the total mass of the fermentation liquid at the end of the first stage of fermentation.

[0041] Step 5, Second sterilization treatment: After filtering the fermentation broth, it is preheated, degassed, homogenized, and then subjected to ultra-high temperature instantaneous sterilization. The preheating temperature is 60~70℃, the degassed vacuum degree is -0.06 ~ -0.07MPa, the homogenization pressure is 10~20 MPa, and the homogenizer operating frequency is 40~45 Hz; the ultra-high temperature instantaneous sterilization process conditions are 115±0.5℃ and a holding time of 15 seconds.

[0042] Step 6: Fill the bottles to obtain the fermented orange juice product.

[0043] Comparative Example 1

[0044] This comparative example prepared fermented orange juice according to the method in Example 1, the difference being that no orange oil was added, and only a single strain of *Lactobacillus plantarum* was used for fermentation. The fermentation process is as follows:

[0045] After sterilization, the material was cooled to 37°C and inoculated with *Lactobacillus plantarum* (Chr. Hansen Harvest LB-1 strain). The inoculation amount was... ~ Fermentation was carried out at a constant temperature of 37℃ with CFU / g. The changes in soluble solids and pH were monitored. When the soluble solids content in the fermentation broth was 18±1.5% and the pH was 3.9±0.15, the fermentation was completed and the original fermentation broth was obtained.

[0046] Comparative Example 2

[0047] This comparative example prepared fermented orange juice according to the method in Example 1, the difference being that orange peel extract was not added, and orange oil was added during the pre-fermentation blending stage. Only a single strain of Lactobacillus plantarum was used for fermentation. The specific preparation steps are as follows:

[0048] Step 1, base solution preparation: Based on the total mass of the final prepared base solution, add 300 g / kg of concentrated orange juice and 0.5 g / kg of orange oil. Add water to adjust the soluble solids content of the system to 19.0±0.5%. Then prepare a 20% potassium hydroxide solution and adjust the pH of the system to 4.5±0.1 to obtain the prepared base solution.

[0049] Step 2, First sterilization treatment: Same as the steps in Example 1.

[0050] Step 3, Fermentation Treatment: Cool the sterilized base liquid to 37°C, and inoculate with *Lactobacillus plantarum* (Chr. Hansen Harvest LB-1 strain) at an inoculation amount of... ~ Fermentation was carried out at CFU / g under constant temperature conditions, and the changes in soluble solids and pH were monitored until the soluble solids content of the fermentation broth was 18±1.5% and the pH was 3.9±0.15. The fermentation was then completed and the fermentation stock solution was obtained.

[0051] Step 4, second sterilization and filling: same as the steps in Example 1.

[0052] Comparative Example 3

[0053] This comparative example uses a conventional fermented orange juice process, employing only concentrated orange juice as raw material and a single strain of *Lactobacillus plantarum* for fermentation, without adding orange peel extract or orange oil. The preparation steps are as follows:

[0054] Step 1, base solution preparation: Based on the total mass of the final prepared base solution, add 300g / kg of concentrated orange juice, add water to make up to the total mass of the system, and adjust the soluble solids content to 19.0±0.5%; adjust the pH to 4.5±0.1 using a 20% potassium hydroxide solution to obtain the prepared base solution.

[0055] Step 2, First sterilization treatment: Same as the steps in Example 1.

[0056] Step 3, Fermentation Treatment: After sterilization, the material is cooled to 37°C and inoculated with *Lactobacillus plantarum* (Chr. Hansen HarvestLB-1 strain) at an inoculation rate of [missing information]. ~ Fermentation was carried out at a constant temperature of 37℃ with CFU / g, and the changes in soluble solids and pH were monitored until the soluble solids in the fermentation broth reached 18±1.5% and the pH reached 3.9±0.15.

[0057] Step 4, second sterilization and filling: same as the steps in Example 1.

[0058] Comparative Example 4

[0059] This comparative example prepared fermented orange juice according to the method in Example 1, the difference being that the orange oil was added during the pre-fermentation blending stage, and only a single strain of *Lactobacillus plantarum* was used for fermentation. The preparation steps are as follows:

[0060] Step 1, Preparation of orange peel extract: Same as the steps in Example 1.

[0061] Step 2, base solution preparation: Mix the concentrated orange juice with the orange peel extract and orange oil described in Step 1. Based on the total mass of the final base solution, the amount of concentrated orange juice added is 300 g / kg, the amount of orange peel extract added is calculated based on the mass of dried orange peel, and the amount added based on dried orange peel is 15 g / kg. The amount of orange oil added is 0.5 g / kg. Add water to adjust the soluble solids content of the system to 19.0±0.5%, then prepare a 20% potassium hydroxide solution and adjust the pH of the system to 4.5±0.1 to obtain the base solution.

[0062] Step 3, First sterilization treatment: Same as the steps in Example 1.

[0063] Step 4, Fermentation Treatment: After sterilization, the material is cooled to 37°C and inoculated with *Lactobacillus plantarum* (Chr. Hansen HarvestLB-1 strain) at an inoculation rate of [missing information]. ~ Fermentation was carried out at a constant temperature of 37℃ with CFU / g, and the changes in soluble solids and pH were monitored until the soluble solids in the fermentation broth reached 18±1.5% and the pH reached 3.9±0.15.

[0064] Step 5, second sterilization and filling: same as the steps in Example 1.

[0065] Comparative Example 5

[0066] This comparative example prepares fermented orange juice according to the method in Example 1, the difference being that the orange oil is added during the pre-fermentation blending stage. The preparation steps are as follows:

[0067] Step 1, Preparation of orange peel extract: Same as the steps in Example 1.

[0068] Step 2, base solution preparation: Mix the concentrated orange juice with the orange peel extract and orange oil described in Step 1. Based on the total mass of the final base solution, the amount of concentrated orange juice added is 300 g / kg, the amount of orange peel extract added is calculated based on the mass of dried orange peel, and the amount added based on dried orange peel is 15 g / kg. The amount of orange oil added is 0.5 g / kg. Add water to adjust the soluble solids content of the system to 19.0±0.5%, then prepare a 20% potassium hydroxide solution and adjust the pH of the system to 4.5±0.1 to obtain the base solution.

[0069] Step 3, First sterilization treatment: Same as the steps in Example 1.

[0070] Step 4, Fermentation Treatment: After sterilization, the material is cooled to 37°C and inoculated with *Lactobacillus plantarum* (Chr. Hansen strain HarvestLB-1) and *Lactobacillus paracasei* (Chr. Hansen strain L. casei-01), with an inoculation amount of 1.5%. ~ Fermentation was carried out at a constant temperature of 37℃ with CFU / g, and the changes in soluble solids and pH were monitored until the soluble solids in the fermentation broth reached 18±1.5% and the pH reached 3.9±0.15.

[0071] Step 5, second sterilization and filling: same as the steps in Example 1.

[0072] Comparative Example 6

[0073] This comparative example prepares fermented orange juice according to the method in Example 1, the difference being that the orange oil is added after fermentation and before the second sterilization. The preparation steps are as follows:

[0074] Step 1, Preparation of orange peel extract: Same as the steps in Example 1.

[0075] Step 2, base liquid preparation: Same as the steps in Example 1.

[0076] Step 3, First sterilization treatment: Same as the steps in Example 1.

[0077] Step 4, Fermentation Treatment: Cool the sterilized base liquid to 37°C, and inoculate with *Lactobacillus plantarum* (Chr. Hansen Harvest LB-1 strain) and *Lactobacillus paracasei* (Chr. Hansen L. casei-01 strain). The inoculation amount of both strains is [missing information]. ~ Fermentation was carried out at CFU / g under constant temperature conditions, and the changes in soluble solids and pH were monitored until the soluble solids content of the fermentation broth was 18±1.5% and the pH was 3.9±0.15. The fermentation was then completed and the fermentation stock solution was obtained.

[0078] Step 5, Second Sterilization Treatment: After filtering the fermentation broth, add 0.5 g / kg of orange oil to the broth based on its total mass. Stir well, then perform preheating, degassing, and homogenization treatments in sequence, followed by ultra-high temperature instantaneous sterilization. The sterilization and filling conditions are the same as those in Example 1.

[0079] Test Example 1: Determination of Basic Physicochemical Indicators

[0080] This test case examined the basic physicochemical properties of the fermented orange juice products prepared in the above examples and comparative examples, including soluble solids, pH value, and total acid content.

[0081] The test results are shown in Table 1.

[0082] Table 1. Detection results of physicochemical properties of fermented orange juice

[0083]

[0084] As shown in the table above, the soluble solids content and pH values ​​of the Examples and Comparative Examples are not significantly different. The total acidity of Examples, Comparative Example 5, and Comparative Example 6 is slightly higher than that of the other comparative examples, indicating that the fermentation of *Lactobacillus plantarum* combined with *Lactobacillus paracasei* produces more acid. The fermentation times of Comparative Examples 2, 4, and 5 are significantly longer than those of the Examples and other comparative examples, indicating that adding orange oil before fermentation inhibits bacterial growth and reproduction, thus prolonging the overall fermentation time. The fermentation time of the Examples is shorter than that of Comparative Examples 4 and 5, indicating that adding orange oil during fermentation can significantly shorten the overall fermentation time.

[0085] Test Example 2: Sensory Evaluation

[0086] This test case evaluates the sensory properties of the fermented orange juice products prepared in the above embodiments and comparative examples.

[0087] A panel of six trained personnel conducted a sensory evaluation of the fermented orange juice, and the final sensory score was the average of the scores. The sensory evaluation criteria for the fermented orange juice are shown in the table below:

[0088]

[0089] The sensory evaluation results are shown in Table 2:

[0090] Table 2 Sensory evaluation results of fermented orange juice

[0091]

[0092] Sensory evaluation results showed that the fermented orange juice prepared in the examples had better aroma, taste and overall harmony than the fermented orange juice prepared in the comparative examples. Furthermore, the bitterness of the examples, comparative examples 5 and 6 was significantly weaker than that of comparative examples 1 and 4, indicating that fermentation with Lactobacillus plantarum and Lactobacillus paracasei can improve the bitterness of the fermented orange juice.

[0093] Test Example 3: Detection of Flavor Compounds

[0094] The flavor compounds of the fermented orange juice prepared in the above examples and comparative examples were determined and analyzed using GC-MS. The specific methods are as follows:

[0095] Instruments: GC-MS (Agilent 7890A-5975C), Zhida CTC multi-function injector, DB-WAX UI column (60m × 250 μm × 0.25 μm, Agilent).

[0096] Reagents: n-Alkanes standard (Sigma-Aldrich), n-hexane (chromatographic grade, Shanghai Anpu).

[0097] Sample preparation: Weigh 2g NaCl, accurately measure 5mL of sample, accurately pipette 5 μL of α-methylcinnamaldehyde solution (1000 mg / L) into a 20 mL headspace vial, seal and wait for testing.

[0098] SPME method: Extraction head was 50 / 30 μm PDMS / DVB / CAR (1 cm, Supelco). Equilibration was performed at 45°C for 15 min, followed by extraction at 45°C for 40 min, and then desorption at the injection port for 5 min. The incubator was oscillated at 500 rpm. The extraction head was kept at 260°C before and after extraction and desorption. The samples were aged for 10 minutes and 5 minutes under different environmental conditions.

[0099] GCMS conditions: Injector temperature 240℃, split injection, split ratio 10:1, carrier gas high-purity He, constant flow mode, carrier gas flow rate 1 mL / min; temperature program: 40℃ held for 3 min, then increased to 130℃ at 5℃ / min, held for 5 min, then increased to 200℃ at 5℃ / min, and finally increased to 240℃ at 20℃ / min, held for 15 min; transfer line temperature 260℃, MS scan range 35~450 m / z, ion source temperature 230℃, quadrupole temperature 150℃, electron energy 70 eV.

[0100] Compound qualitative method: Mass spectrometry fragment information of the sample was compared with Nist 2020 database using Masshunter Unknown Analysis software to obtain compound information. The retention index (RI) of the compound was verified with the RI value in the database. An absolute value of the RI difference of less than or equal to 50 was acceptable. The n-alkane standards were analyzed by GC-MS under the same instrument conditions as the samples, and the RI value of the unknown compounds was calculated using the obtained alkane retention times.

[0101] The analysis results are shown in Table 3. A total of 35 flavor compounds were detected. The number of flavor compounds in the examples was significantly greater than in comparative examples 1, 2, and 3. A total of 28 flavor compounds were detected in the examples. Among them, terpinene has a citrus and woody aroma; limonene has a citrus aroma and is the most abundant component in orange oil (up to 80-90%), which is the main source of the characteristic aroma of orange oil; linalool has a floral and sweet aroma and is highly active, contributing significantly to the richness and complexity of the aroma; terpinene-4-ol has a spicy and woody aroma; β-phellandrene has a peppery and herbal aroma and is one of the characteristic aroma components of citrus; α-terpinene has a citrus and lemony aroma and is one of the terpinene isomers, contributing a fresh citrus note; α-pinene has a pine and resinous aroma. These substances mainly come from orange peel and orange oil, which enrich the aroma of fermented orange juice.

[0102] Compared to the examples, Comparative Example 6 showed a higher concentration of limonene, linalool, γ-terpinene, β-myrcene, and α-pinene. These substances mainly originate from orange oil. Since the orange oil in Comparative Example 6 was added after fermentation, these flavor compounds were less lost. However, these flavor compounds did not contribute positively to the aroma; instead, they made the overall aroma of Comparative Example 6 unbalanced and irritating. Furthermore, adding orange oil after fermentation affects the stability of the fermented orange juice system. Orange oil is not easily soluble in fermented orange juice and will form an oil ring-like float on the surface, affecting the appearance.

[0103] Finally, it should be noted that the above description is only used to illustrate the technical solutions of the present invention and is not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention.

[0104]

[0105]

[0106]

Claims

1. A method for preparing fermented orange juice, comprising the steps of preparing orange juice base liquid, sterilization, inoculation with lactic acid bacteria for fermentation, and post-fermentation sterilization, characterized in that, The preparation method includes the following steps: Step 1, Preparation of orange peel extract: Mix dried orange peel with water, heat and extract, filter and collect the filtrate to obtain orange peel extract; Step 2, base solution preparation: Mix the concentrated orange juice with the orange peel extract described in Step 1, add water to adjust the soluble solids content of the system to 19.0±0.5%, and then adjust the pH of the system to 4.5±0.1 to obtain the prepared base solution; Step 3, First sterilization treatment: After filtering the prepared base solution, it is preheated, degassed, homogenized and then subjected to ultra-high temperature instantaneous sterilization. Step 4, Segmented Fermentation: Cool the sterilized base liquid to 36~38℃, inoculate with *Lactobacillus plantarum* and *Lactobacillus paracasei*, and carry out the first stage of fermentation under constant temperature conditions; when the pH of the fermentation liquid drops to 4.3±0.1, add orange oil to the fermentation liquid and continue the second stage of fermentation until the soluble solids content of the fermentation liquid is 18±1.5% and the pH is 3.9±0.15, and the fermentation is completed to obtain the fermentation stock liquid; Step 5, Second sterilization treatment: After filtering the fermentation liquid, it is preheated, degassed, and homogenized in sequence, and then subjected to ultra-high temperature instantaneous sterilization to obtain the fermented orange juice product.

2. The preparation method according to claim 1, characterized in that, In step 1, the mass ratio of dried orange peel to water is 1:30~40, the extraction temperature is 85~95℃, and the extraction time is 5~20 minutes.

3. The preparation method according to claim 1, characterized in that, In step 2, based on the total mass of the final prepared base liquid, the amount of concentrated orange juice added is 250~350 g / kg; the orange peel extract is added according to the mass of dried orange peel, and the amount added based on dried orange peel is 10~20 g / kg, and the remaining amount of the prepared base liquid is made up with water.

4. The preparation method according to claim 1, characterized in that, In step 2, the pH of the system is adjusted using a 20% potassium hydroxide solution.

5. The preparation method according to claim 1, characterized in that, In steps 3 and 5, the preheating temperature is 60~70℃, the degassing vacuum degree is -0.06 ~ -0.07MPa, the homogenization pressure is 10~20 MPa, and the homogenizer operating frequency is 40~45Hz; the ultra-high temperature instantaneous sterilization process conditions are a temperature of 115±0.5℃ and a holding time of 15 seconds.

6. The preparation method according to claim 1, characterized in that, In step 4, based on the mass of the sterilized base liquid, the inoculation amounts of *Lactobacillus plantarum* and *Lactobacillus paracasei* are both... ~ CFU / g.

7. The preparation method according to claim 1 or 6, characterized in that, The plant lactobacillus is Chr. Hansen's Harvest LB-1 strain, and the paracasei lactobacillus is Chr. Hansen's L. casei-01 strain.

8. The preparation method according to claim 1, characterized in that, In step 4, the amount of orange oil added is 0.2~1.0 g / kg, based on the total mass of the fermentation liquid at the end of the first stage of fermentation.

9. The preparation method according to claim 1, characterized in that, In step 4, the constant temperature fermentation temperature is 37℃, and the total fermentation time is 24~72 hours.

10. A fermented orange juice, characterized in that, The fermented orange juice is prepared by any one of the methods described in claims 1 to 9.

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