Fermented citrus reiculata Blanco wine with peel and preparation method thereof

Abstract

The invention belongs to the technical field of fruit wine brewing, and particularly relates to fermented citrus reiculata Blanco wine with peels and a preparation method thereof.The preparation method comprises the following steps that S1, raw material pretreatment is conducted, specifically, pectinase or pectinase and naringinase are added into juice with different peel removal rates, and treatment is conducted for 2-3 h at the temperature of 35-45 DEG C; s2, sulfur treatment: adding potassium metabisulfite at 35-45 DEG C, and uniformly stirring; s3, yeast inoculation: optimizing and screening yeast with bitterness inhibiting characteristics, and inoculating the pre-activated yeast according to 1 * 10 < 6 > CFU / mL; s4, main fermentation: performing constant-temperature fermentation at 22-30 DEG C, and stopping fermentation when residual sugar is less than or equal to 4g / L; and S5, post-treatment: carrying out cold stabilization and clarification at 0-10 DEG C for 7 days, separating, and taking a supernatant to finally obtain the citrus reiculata Blanco wine. According to the scheme, the technical problem of lack of characteristic aroma due to the fact that peels need to be removed during fermentation of citrus fruit wine in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the field of fruit wine brewing technology, and specifically relates to a fermented Wogan orange wine with peel and its preparation method. Background Technology

[0002] Wogan mandarin oranges are currently the fastest-growing citrus variety in China, dominating the late-ripening fresh fruit market. They possess advantages such as a balanced sugar-acid ratio, vibrant color, and unique flavor, making them a high-quality raw material for fruit wine production. Citrus peels are rich in volatile compounds such as terpenes. To enhance the unique flavor of fruit wines, the peel can be considered as one of the sources of the distinctive flavor of citrus-based wines. However, naturally occurring terpenes in citrus peels (such as limonene) have antibacterial properties. Studies have shown that when the concentration of limonene in citrus peel exceeds 1500-3000 ppm, it significantly inhibits the metabolic activity of brewer's yeast, leading to a decrease or even stagnation in fermentation efficiency. This inhibitory effect stems from the damage of limonene to the yeast cell membrane, hindering its normal respiration and sugar metabolism processes. Therefore, most citrus fermented fruit wines currently use the juice after peeling and deseeding as the fermentation substrate. For example, patent application number CN202211639848.X, "A mixed fermentation citrus fruit wine and its brewing method", and patent application number CN202510305957.5, "Preparation method of fruit wine based on citrus fruit koji fermentation", both mention that the peel needs to be removed before fermenting the fruit wine.

[0003] Currently, systematic research on the impact of fruit peel on the fermentation process and quality of citrus wine is scarce, and there are no reports on related Wogan orange wine fermented with peel and its preparation methods. This technical solution fills the technological gap in the fermentation process of citrus wine with peel, providing an innovative path to enhance product added value. Summary of the Invention

[0004] The present invention aims to provide a fermented citrus wine with peel and its preparation method, mainly to solve the technical problem in the existing technology that the peel needs to be removed when fermenting citrus fruit wine, resulting in a lack of characteristic aroma.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing fermented Wogan orange wine with peel includes the following steps:

[0007] S1: Raw material pretreatment enzymatic hydrolysis and clarification: Juice is extracted from some of the peeled Wogan tangerines, pectinase preparation is added to the juice, and the mixture is treated in a water bath at 35-45℃ for 2-3 hours.

[0008] S2: Sulfur treatment: Add potassium metabisulfite at 35-45℃ and stir until homogeneous;

[0009] S3: Yeast inoculation: Optimize the screening of yeast with anti-bitterness properties, and inoculate pre-activated yeast at 1×10^6 CFU / mL;

[0010] S4: Primary fermentation: constant temperature fermentation at 22-30℃, terminate when residual sugar ≤4g / L;

[0011] S5: Post-processing: After clarification at 0-10℃ for 7 days, the supernatant is separated and the final product is Wogan wine.

[0012] Preferably, the yeast used in step S3 is Saccharomyces cerevisiae YQMSF2-4, which was deposited on May 24, 2024, at the Guangdong Provincial Microbial Culture Collection Center (GDMCC), located at No. 100 Xianlie Middle Road, Guangzhou, Guangdong Academy of Sciences, with accession number GDMCC No: 64680.

[0013] Preferably, in step S1, the juice is obtained by juicing Wogan oranges with a peel removal rate of 80% to 100%.

[0014] Preferably, in step S1, the juice is obtained by juicing Wogan oranges with a peel removal rate of 80%.

[0015] Preferably, in step S2, the amount of potassium metabisulfite added is 100 mg / L.

[0016] Preferably, in step S1, the enzyme preparation includes one or both of pectinase at an addition amount of 100 mg / L and naringinase at an addition amount of 200 mg / L.

[0017] Preferably, in step S3, before inoculating the yeast, the yeast is first added to a 5% glucose solution and pre-activated at 30°C for 30 minutes.

[0018] Preferably, in step S4, the fermentation process is monitored by CO2 weight loss method.

[0019] A fermented Wogan orange wine with peel, prepared by a method for preparing fermented Wogan orange wine with peel.

[0020] Application of a brewing yeast, YQMSF2-4, in fermented Wogan orange wine with peel.

[0021] The beneficial effects of this invention are:

[0022] (1) This solution breaks through the traditional process of fermenting citrus raw materials into fruit wine by removing the peel. It selects self-selected brewing yeast (Saccharomyces cerevisiae) YQMSF2-4 to ferment Wogan wine with peel, so that the wine can maintain a harmonious aroma, gloss, balanced taste, and obvious citrus aroma. It can effectively maintain the citrus flavor of the wine while avoiding the bitterness brought by the peel. It solves the technical problem of the lack of characteristic aroma caused by the removal of peel when fermenting citrus fruit wine in the existing technology.

[0023] (2) This scheme further effectively changes the aroma composition and sensory quality of Wogan wine by adjusting the peel removal rate, so that the wine can maintain the volatile aroma of terpenes and avoid bitterness. Through a large number of experiments, it was found that 80% peel removal rate was the optimal peel removal rate in this study when fruit wine was fermented with Saccharomyces cerevisiae YQMSF2-4, so that the wine and its fermentation process can take into account better fermentation efficiency, flavor complexity and product acceptance.

[0024] (3) Naringinase is a complex enzyme that typically contains α-L-rhamnosidase and β-D-glucosidase activities. It can specifically hydrolyze the sugar groups on these bitter glycoside molecules to generate aglycones and sugar molecules that are almost without bitterness. By adding naringinase before fermentation, most of the potential sources of bitter substances can be decomposed before the main fermentation begins. Moreover, hydrolysis products such as aglycones are easily metabolized by yeast into more abundant and typical volatile compounds with floral and fruity aromas.

[0025] At the same time, the use of naringinase in conjunction with the existing pectinase helps to further break down the complex macromolecules and colloidal networks that bind with bitter substances in the juice, thereby synergistically improving the clarification efficiency of the subsequent step S5 and obtaining a clearer and more stable Wogan orange wine.

[0026] In summary, adding naringinase can significantly reduce the bitterness of the final Wogan wine while preserving the citrus flavor, and improve the roundness, pleasantness, and clarity of the taste. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0028] Figure 1 This is a statistical chart showing the detection of bitter substances in Wogan orange wine fermented with peel and its preparation method after fermentation with different yeasts according to the present invention patent.

[0029] Figure 2 This is a statistical chart showing the detection of bitter substances in a fermented Wogan orange wine with peel and its preparation method under different amounts of naringinase addition, as described in this invention patent.

[0030] Figure 3 This is a statistical chart showing the detection of bitter substances in Wogan orange wine with peel fermentation and its preparation method after adding naringinase at different removal rates.

[0031] Figure 4 Juice yield of Wogan mandarin oranges under different peel removal rates in the preparation method of a fermented Wogan mandarin orange wine with peel (different letters indicate significant differences (P<0.05));

[0032] Figure 5 This invention patent describes the weight loss rate of fermented Wogan orange wine under different peel removal rates during fermentation, based on a method for preparing Wogan orange wine with peel.

[0033] Figure 6A Upset-Venn plot of volatile aroma crossover relationship of Wogan juice / wine in a fermented Wogan wine with peel and its preparation method according to this invention patent;

[0034] Figure 6B This is a diagram showing the relative content distribution of various volatile aroma components in the Wogan juice / wine of a fermented Wogan tangerine wine with peel and its preparation method, which is a patented invention.

[0035] Figure 6C This is an analysis chart of the absolute content of various volatile aroma components in a fermented Wogan orange wine with peel and its preparation method, which is a patent of this invention.

[0036] Figure 6D This is an analysis chart of the absolute content of various volatile aroma components in the Wogan juice of a fermented Wogan wine with peel and its preparation method, which is a patent of this invention.

[0037] Figure 7 Bubble graph showing the content and OAV value of volatile aroma substances (OAV > 0.1) in a fermented Wogan orange wine with peel and its preparation method, which is a patent of this invention.

[0038] Figure 8A PLS-DA analysis of the fermented Wogan orange wine with peel and its preparation method, which is a patent of this invention.

[0039] Figure 8B Upset-Venn plot of volatile aroma compounds based on VIP>1 and OAV>1 for a fermented Wogan orange wine with peel and its preparation method, which is a patent of this invention.

[0040] Figure 9This invention patent presents a QDA sensory analysis radar chart of Wogan orange wine with peel fermentation and its preparation method, showing different peel removal rates of Wogan orange wine.

[0041] Strain Preservation Notes: The Saccharomyces cerevisiae YQMSF2-4 of this invention was deposited on May 24, 2024, at the Guangdong Provincial Microbial Culture Collection Center (GDMCC), located at No. 100 Xianlie Middle Road, Guangzhou, Guangdong Academy of Sciences, Institute of Microbiology, with accession number GDMCC No: 64680. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. Where the terms "first," "second," and "third" are used for descriptive purposes and to distinguish technical features, they should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0044] The embodiments of the present invention will now be described.

[0045] Example 1:

[0046] A method for preparing fermented Wogan orange wine with peel, including

[0047] S1: Raw material pretreatment: Juice is extracted from Wogan oranges with 80% peel removal rate, pectinase is added to the juice at a rate of 100 mg / L, and the juice is treated in a 40℃ water bath for 2 hours.

[0048] S2: Sulfur treatment: Add potassium metabisulfite and stir until homogeneous. The amount of potassium metabisulfite added is 100 mg / L.

[0049] S3: Yeast inoculation: Optimize and screen yeast with anti-bitterness properties. Add the yeast to a 5% glucose solution and pre-activate it at 30°C for 30 min. Then, inoculate the pre-activated yeast into the juice treated with sulfur in step S2 at 1×10^6 CFU / mL. The yeast is Saccharomyces cerevisiae YQMSF2-4, which was deposited on May 24, 2024, at the Guangdong Provincial Microbial Culture Collection Center (GDMCC), located at No. 100 Xianlie Middle Road, Guangzhou, Guangdong Academy of Sciences, Institute of Microbiology, with accession number GDMCC No: 64680.

[0050] S4: Primary fermentation: constant temperature fermentation at 20±2℃, with fermentation progress monitored by CO2 weight loss method, and terminated when residual sugar ≤4g / L;

[0051] S5: Post-processing: After clarification at 4℃ for 7 days, the supernatant was separated and the final product, Wogan wine, was obtained.

[0052] Example 2:

[0053] Unlike Example 1, in step S1, naringinase is also added at a concentration of 200 mg / L.

[0054] Comparative Example 1:

[0055] Unlike Example 1, the peel of the Wogan mandarin orange was 100% removed.

[0056] Comparative Example 2:

[0057] Unlike Example 1, the peel removal rate of the Wogan mandarin oranges was 50%.

[0058] Comparative Example 3:

[0059] Unlike Example 1, the peel removal rate of the Wogan mandarin oranges was 0%.

[0060] Comparative Examples 4-12:

[0061] Unlike Example 1, the yeasts used were, in order, commercially available LAMMEND series 71B, Diboshi dry yeast B0213, LAFFORT dry yeast F15, EC1118, ST, K1, R-HST, PM, and Angel dry yeast SY.

[0062] Experimental example:

[0063] Comparative Example 1 was used as the control group, and Examples 1, 2, and 3 were used as the treatment groups. The Wogan juice obtained in step S1 of Comparative Example 1, Examples 1, 2, and 3 were designated as J0, J1, J2, and J3, respectively; the Wogan wine obtained in step S5 was designated as W0, W1, W2, and W3, respectively. Each example and comparative example had 3 biological replicates, and the following tests were performed.

[0064] 1. The effect of yeast on the quality of Wogan orange wine

[0065] Sensory evaluation was conducted on the Wogan wines from Comparative Examples 4-12 and Example 1. The results are shown in the table below:

[0066] Table 2: Sensory evaluation of Wogan orange wine compared with Comparative Examples 4-12 and Examples 1 and 2

[0067]

[0068]

[0069] The results are shown in Table 2. Different yeasts had different effects on the sensory development of Wogan orange wine. Among the 10 yeasts investigated in this experiment, 9 commercially available strains tended to have a pronounced bitter taste. The Wogan orange wine of Example 1 was glossy, clear, and transparent, with a harmonious aroma, Wogan orange flavor, and a balanced and pure taste without bitterness. It was superior to Wogan orange wine brewed with other commercially available yeasts, proving that the use of Saccharomyces cerevisiae YQMSF2-4 can effectively maintain the citrus flavor of the wine while avoiding bitterness from the peel. In Example 2, the wine had a harmonious aroma, gloss, a clear body, a balanced taste, a distinct citrus aroma, and no bitterness. Its color, aroma, and flavor were all excellent, indicating that the addition of naringinase had a significant promoting effect on the overall clarification of the wine.

[0070] The bitter substances in the Wogan wines obtained in Comparative Examples 4-12 and Example 1 were detected, and the results are as follows: Figure 1 As shown, detailed statistics are presented in Table 3 below:

[0071] Table 3: Detection of bitter substances in Wogan orange wine in Comparative Examples 4-12 and Example 1

[0072]

[0073] The total content of bitter substances in the fermentation products of strain YQMSF2-4d was the lowest (slightly below 10 mg / L), proving that yeast YQMSF2-4d is indeed more effective than commercially available yeasts in removing bitterness from fruit wine.

[0074] 2. Effect of naringinase on the bitterness of Wogan orange wine

[0075] (1) Referring to the process steps of Comparative Example 1, five test cases were set up. Naringinase was added to each case in step S1 at concentrations of 0 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, and 400 mg / L, respectively. The bitter substances in the Wogan wine obtained from each test case were detected, and the results are shown in Table 4 below. Figure 2

[0076] Table 4: Detection of bitter substances in Wogan orange wine at different amounts of naringinase addition

[0077]

[0078]

[0079] Through testing, the content of bitter substances was lowest when the amount of naringinase added was 200 mg / L among the five test cases, thus determining 200 mg / L as the optimal addition amount.

[0080] In step S1 of Comparative Example 1, Example 1, Comparative Example 2, and Comparative Example 3, 200 mg / L of naringinase was added for juice fermentation. The final Wogan orange wines (W0A, W1A, W2A, W3A) were then analyzed for bitter substances, and the results were as follows: Figure 3 and

[0081] As shown in Table 5:

[0082]

[0083] The results of YQMSF2-4d and naringinase treatment showed that there was no significant difference in the content of bitter substances between 80% (W1A) and 100% (W0A) peeling treatments, supporting the conclusion that 80% peeling rate is the superior process. Furthermore, the experimental results of W1A provided support for the quality of the Wogan wine product in Example 2, which has good quality in both flavor and taste.

[0084] 3. Effect of peel removal rate on juice yield of Wogan mandarins

[0085] Juice yield test results are as follows Figure 4 As shown.

[0086] Juice yield is a core indicator for measuring raw material utilization efficiency and ensuring wine yield; its value directly reflects the proportion of juice that can be extracted from the fruit. For example... Figure 1 As shown, the juice yield and the peel removal rate were significantly positively correlated (Pearson's r = 0.9912, R0). 2=0.9525, P<0.01). The control group J0 had the highest juice yield (58.10%), while the juice of Wogan mandarin oranges treated with 80% peel removal rate J1 (57.14%) showed no significant difference. However, as the peel removal rate further decreased, the juice yield decreased to 52.00% (J2) and 44.00% (J3), respectively. This phenomenon may be due to the rich pectin, cellulose, and lignin in the peel of Wogan mandarin oranges, which makes the cell wall structure of the pulp compact, increasing the resistance of the cell wall to juice release during juicing. The resistance of the pulp cell wall increases significantly with the decrease in peel removal rate, making it more difficult for juice to be squeezed out of the pulp, thus reducing the juice yield. It is worth noting that when the peel removal rate is ≥80%, the inhibition of fermentation by the peel has been basically eliminated, and the marginal benefit of further increasing the peel removal rate approaches saturation. 17 Therefore, considering both raw material costs and juice extraction efficiency, it is recommended that the peel removal rate be controlled at no less than 80% in the production of Wogan orange wine, so as to achieve the best balance between economic benefits and process efficiency while ensuring sufficient fermentation substrate.

[0087] 4. The effect of peel removal rate on the fermentation of Wogan orange wine

[0088] The fermentation process was monitored using the CO2 weight loss method, and the results are as follows: Figure 5 As shown.

[0089] While fruit peels impart characteristic aromas to fruit wines, their potential impact on fermentation parameters still warrants close attention. For example... Figure 2 As shown, monitoring the fermentation weight loss rate of four groups of samples with different peel removal rates (W0–W3) revealed that the peel removal rate significantly affects fermentation efficiency. The control group W0 exhibited the best fermentation characteristics, with a weight loss rate of 2.51% on the first day, exceeding 4% within three days before entering a stable period. While W1's initial rate was slightly slower than W0, the overall trend was largely the same. W2 showed a delayed fermentation phenomenon, with a lag period of up to three days; by day 6, the cumulative weight loss rate was only 2.60%, reaching 4% by day 8. Fermentation in W3 was severely inhibited, with a weight loss rate of only 0.51% on day 6 and ultimately only 0.98%, failing to complete alcohol fermentation. These results indicate that to ensure normal alcohol fermentation, the peel removal rate of Wogan tangerines should be controlled above 80% to effectively reduce interference from peel substances and ensure rapid initiation and successful completion of alcohol fermentation.

[0090] 5. Physicochemical properties and color analysis of Wogan orange juice and wine

[0091] Physicochemical index determination methods: Total acid, volatile acid, residual sugar and alcohol content were determined according to GB / T 15038-2006 "General Analytical Methods for Wine and Fruit Wine"; pH value was determined using a pH meter; soluble solids were determined using a handheld saccharimeter.

[0092] Color parameter determination method: The color parameters were determined according to the relevant methods in the literature. A colorimeter was used to detect the samples. After zeroing with distilled water, the L*, a*, and b* values ​​of each wine sample were measured. Each sample was technically replicated 3 times.

[0093] Table 1. Physicochemical properties and color of Wogan juice and wine under different peel removal rates.

[0094]

[0095]

[0096] Note: Different letters in the same column indicate significant differences within the Wogan juice and wine groups (P < 0.05).

[0097] Basic physicochemical indicators and color parameters are the most intuitive quality parameters for evaluating the processing of fruit juice and fruit wine. The effects of different peel removal rates on the basic physicochemical indicators and color parameters of Wogan mandarin orange juice and Wogan mandarin orange wine are shown in Table 1 above.

[0098] The soluble solids content and pH value of the four juice groups did not differ significantly. The total acid content initially increased and then decreased with the removal of peel, with group J1 having the highest total acid content (7.97 g / L), but the overall difference was not significant, indicating that peel components had a limited impact on the sugar-acid balance of Wogan juice. In contrast, the peel removal rate had a more significant impact on the basic physicochemical indicators of Wogan wine. As the peel removal rate decreased, the sugar conversion efficiency decreased, leading to a significant decrease in alcohol content. However, there was no significant difference between W1 and the control group W0, indicating that a peel removal rate of ≥80% can maintain efficient alcohol conversion. The total acid content of Wogan wine was significantly higher than that of Wogan juice, and increased by a 1.72-fold gradient with decreasing peel removal rate (P<0.05, W3 vs W0). The volatile acid content of groups W1, W2, and W3 was significantly higher than that of W0 (P<0.05), with an increase of 5.00–6.18 times, indicating that fermentation with peel promotes the accumulation of volatile acids, which may lead to abnormal volatile acid metabolism in the system.

[0099] L*, a*, and b* represent brightness, red-green value, and yellow-blue value, respectively. 20The results of this study indicate that the peel removal rate significantly affected the L* value of Wogan mandarin orange juice (P<0.05). Compared with the control group J0, J1, J2, and J3 increased by 2.83, 9.47, and 13.55, respectively. The L* value of Wogan mandarin orange wine was generally lower than that of the corresponding Wogan mandarin orange juice, and it peaked at 32.47 at an 80% peel removal rate (W1) before declining, indicating that the fermentation process reduced brightness, but moderately retaining the peel could maintain the brightness of the wine. Regarding the red and green hues, the a* value of Wogan mandarin orange juice changed from positive to negative as the peel removal rate decreased (J0 was more red, J1-J3 were more green), but the absolute difference between groups was ≤1.35. After fermentation, the shift of the a* value of Wogan mandarin orange wine on the red-green axis further decreased to within 1.00, indicating that the peel removal rate and fermentation had limited impact on the red and green hues. The yellow and blue hues showed significant changes. The b* value of Wogan juice increased significantly from 5.66 to 19.88 (P<0.05) as the peel removal rate decreased. Although it decreased overall after fermentation, it still maintained a significant gradient difference from 1.17 to 2.87 (P<0.05), indicating that fermentation with peel has a continuous strengthening effect on the yellow hue of Wogan wine.

[0100] With the increase in peel removal rate, sugar conversion efficiency significantly improved, alcohol content gradually increased, and residual sugar content decreased accordingly. There was no significant difference between W1 and the control group W0, indicating that when the peel removal rate exceeded 80%, alcohol conversion efficiency tended to stabilize. Total acid content was significantly negatively correlated with peel removal rate (Pearson's r = -0.99985, R0). 2 =0.9970, P<0.01), the volatile acid content increased from 6.06 g / L in the W0 treatment to 16.50 g / L in the W3 treatment. The volatile acid content reached a peak of 1.22 g / L in the W2 treatment, which was 2.65 times higher than the control group (P<0.05), indicating that fermentation with skin may cause abnormal volatile acid metabolism in the system.

[0101] 6. Effect of peel removal rate on the content of volatile aroma compounds in Wogan mandarin juice and wine

[0102] Test Method: The headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC–MS) procedure was optimized according to the reference: 5.00 mL of sample, 10 μL of internal standard (0.9898 g / L 4-methyl-2-pentanol), and 1.00 g of sodium chloride were added to the headspace vial. A CTC Analytics fully automated headspace injection system with a DVB / CAR / PDMS (Supelco, 50 / 30 μm*2 cm) extraction head was used. After equilibration at 40 °C for 30 min, extraction was performed for 30 min, followed by desorption for 5 min (250 °C). Mass spectrometry analysis was performed using an Agilent 8890GC-7000E column (60m × 0.25mm × 0.25μm), with a carrier gas flow rate of 1mL / min, a split ratio of 5:1, and a column temperature program of 40℃ to 50℃ (hold for 1 minute, then at 10℃ / min), followed by a rise to 220℃ at 3℃ / min and a hold for 5 minutes. Quantification of volatiles was based on a calibration curve constructed from the internal standard response ratio and concentration ratio. For volatiles without calibration standards, quantification was performed by referring to existing standard substances based on their chemical structural similarity and similar carbon number. Aroma compounds were identified by comparing mass spectra with the NIST 2020 database and by linear retention index (RI, calculated using C7-C20 n-alkanes). Each sample was analyzed three times repeatedly, and the odor activity (OAV) was obtained by calculating the ratio of aroma compound concentration to threshold.

[0103] Test results are as follows Figures 6A-6D As shown.

[0104] The pretreatment method of raw materials significantly affects the complexity and diversity of volatile aroma compounds in fruit juice and fruit wine. This study used HS-SPME-GC-MS to perform qualitative and quantitative analysis of volatile aroma compounds in Wogan mandarin orange juice (J0-J3) and Wogan mandarin orange wine (W0-W3) under four peel removal rate gradients. Figure 3 A- Figure 3 D shows the quantity and common components of volatile aroma substances in Wogan juice and Wogan wine under different peel removal rates, as well as the qualitative and quantitative analysis of terpenes, esters, alcohols, acids and other volatile aroma components and their proportion in the total aroma content.

[0105] A total of 96 volatile aroma compounds were identified in the four groups of Wogan mandarin orange juice, covering terpenes (45), alcohols (19), esters (15), acids (2), and other components (15). The control group (J0) showed only 78 substances, while all 96 components were detected in the peel-containing treatment groups (J1–J3). All five categories of components increased significantly with decreasing peel removal rate (P < 0.05), with the total volatile matter content of J1–J3 being 11.79, 17.57, and 52.88 times that of J0, respectively. Terpenes, as the main volatile components of citrus characteristic aroma, showed a significant negative correlation between their absolute content and peel removal rate (Pearson's r = -0.9749, R0). 2 =0.9505, P<0.05), the terpene content in J1 to J3 increased by 48.15, 72.17, and 234.93 times compared to J0, respectively. Compared with the control group J0, the relative content of terpenes in J1 showed a significant increase, from the initial 21.53% to 89.80% (P<0.05). When the peel removal rate was less than 80%, the increase in terpene content showed a diminishing marginal effect, eventually reaching a peak of 96.08% in J3. The above data indicate that citrus peel plays a decisive regulatory role in the compositional diversity of volatile aroma compounds in citrus juice.

[0106] A total of 96 volatile aroma compounds were detected in Wogan orange wine (W0 93, W1 95, W2 96, W3 92), including 17 terpenes, 32 esters, 26 alcohols, 4 acids, and 17 other compounds. Only 35 aroma compounds were found in both Wogan orange wine and Wogan orange juice. Significant differences in volatile components were observed before and after fermentation, primarily a decrease of 28 terpenes, and an increase of 17 esters and 9 alcohols. The total amount of aroma compounds in Wogan orange wine fluctuated significantly with the peel removal rate (P < 0.05), reaching a peak at W2 (198.21 ± 69.47 mg / L).

[0107] Except for W3, whose fermentation was inhibited, the total aroma compounds in W0, W1, and W2 were all higher than those in the corresponding Wogan mandarin juice. These results indicate that fermentation effectively alters the composition of aroma compounds and promotes an increase in the total aroma content. Notably, the five aroma components exhibited different trends with decreasing peel removal rate, suggesting that peel content has a specific regulatory effect on the formation of different types of aroma compounds. Terpenes are the core components of the characteristic aroma of citrus wine, and their total amount is significantly negatively correlated with peel removal rate (Pearson's r = -0.9529, R0). 2=0.9081, P<0.05), W1 to W3 increased by 22.28, 73.03, and 91.88 times compared to W0, respectively. During fermentation, due to the dual effects of microbial metabolism and acid-catalyzed rearrangement, the total amount of terpenes decreased significantly, with a retention rate of 5.72% to 14.71%, among which D-limonene and β-myrcene showed the most significant decreases, reaching 85% to 95%. Esters make an important contribution to the flavor of Wogan orange wine. The total amount increased significantly by 3.91 to 31.24 times after fermentation, and showed a trend of first increasing and then decreasing as the peel removal rate decreased. W2 had the highest content at 49.52±64.20 mg / L; ethyl lactate was the most abundant ester, mainly from the esterification reaction of lactic acid and ethanol under the action of esterase during fermentation. The proportion of ethyl lactate in W2 and W3 was ≥80%. Excessive ethyl lactate may inhibit the expression of flavor of other esters. 29 Alcohols are the main metabolic products during the fermentation of alcoholic beverages.

[0108] After fermentation, the total amount of alcohols, dominated by higher alcohols such as isobutanol, isoamyl alcohol, and phenylethyl alcohol, increased significantly by 9.83–131.82 times, and showed a significant positive correlation with the peel removal rate (Pearson's r = 0.9912, R0). 2 =0.9824, P<0.01), and the relative proportion gradually decreased from 92.65% (W0) to 52.67% (W3). The acid content of fermented wine samples with peels was significantly higher than that of W0 (P<0.05), with W2 having the highest content, reaching 2.84 times that of W0. This result also indicates that excessive peel content may lead to excessive acidity during fermentation.

[0109] Other substances mainly include ketones and volatile phenols, which contribute to the flavor profile of Wogan tangerines. Their content is comparable to the total content in Wogan tangerine juice and is significantly negatively correlated with the peel removal rate (Pearson's r = -0.9661, R...). 2 =0.9333, P<0.05). Based on the above results, the amount of peel retained not only directly affects the content of characteristic flavor substances of Wogan mandarin such as terpenes, but also effectively optimizes the overall composition of aroma components by influencing the fermentation process and regulating the synthesis pathways of esters, alcohols and acids. Therefore, scientifically controlling the peel removal rate is of great significance for optimizing the original flavor and fermentation efficiency of Wogan mandarin.

[0110] Analysis of key volatile aroma compounds in Wogan orange wine yielded the following results: Figure 4 As shown, in flavor chemistry research, odor activity (OAV) is a key indicator for measuring the contribution of compounds to flavor. When the OAV of a compound in the system is ≥1, it indicates that its content exceeds the odor threshold and can significantly affect the flavor characteristics of the wine. When 0.1≤OAV≤1, the aroma compound has the potential to contribute to the overall aroma of the wine sample.

[0111] Figure 7 The concentration distribution characteristics of 53 aroma components with OAV ≥ 0.1 in each wine sample and their OAV value distribution are presented. The bubble diagram size corresponds to the compound concentration gradient, and the bubble color represents the OAV value range.

[0112] A total of 38 aroma compounds with an OAV ≥ 1 were found in the four groups of experimental wine samples. Among them, nine compounds—D-limonene, L-rosinone, isovaleric acid, caprylic acid, n-octanol, ethyl caprylate, ethyl 3-hydroxyhexanoate, (1R,5R)-carvacrol, and 4-ethylguaiacol—all showed an OAV ≥ 1 in all four groups of wine samples, and are key substances in the flavor composition of Wogan orange wine. Among them, D-limonene (floral, green, and citrus aroma) in W3 had the highest OAV value, reaching 786.61, and is the most important terpene. Ethyl caprylate (sweet and fruity aroma), isovaleric acid (cheesy and oily), and ethyl 3-hydroxyhexanoate (fresh aroma) all had an OAV greater than 10 in all four groups of wine samples, and are important aroma substances in the wine samples. Although the content of isobutanol and isoamyl alcohol is high, their odor thresholds are high (40 mg / L and 65 mg / L, respectively), resulting in OAV values ​​ranging from 0.15 to 1.19 and 0.23 to 1.52, which have a limited impact on the aroma of the wine.

[0113] A comparison of the content of relevant substances in Wogan mandarin orange juice reveals that the above nine key aroma substances mainly originate from two aspects: the inherent aroma components of the raw materials and the derivative aroma substances formed during fermentation. 32 Analysis based on the trend of substance concentration changes in the bubble chart ( Figure 4The peel removal rate exhibits four regulatory modes on key aroma compounds. D-limonene, n-octanol, L-rosinone, and (1R,5R)-carvacrol, mainly derived from Wogan mandarin oranges (characterized by citrus, floral, and herbal aromas), all showed a negative correlation with the peel removal rate. The total amount of these four substances in W1 accounted for 27.70% of the whole-fruit fermentation, indicating that a peel removal rate ≥80% would lead to excessive loss of characteristic Wogan mandarin orange aromas. Isovaleric acid and 4-ethylguaiacol, mainly derived from the fermentation process, significantly increased with decreasing peel removal rate (P<0.05). While a peel removal rate ≤50% could promote the formation of 4-ethylguaiacol (fragrance and clove aroma characteristics), it also led to excessive accumulation of isovaleric acid (volatile organic acid) (significantly increasing its content by more than 30%), potentially negatively impacting the flavor of the fruit wine. Ethyl octanoate and octanoic acid (characteristic of fruit and cheese aroma) are derived from the raw materials and fermentation process of Wogan oranges. Their contents showed a trend of first increasing and then decreasing, reaching peak values ​​in W1 and W2 (with no significant difference between groups), and increasing by 72.88% and 75.70% respectively compared with the control group W0. Ethyl 3-hydroxyhexanoate (fruit aroma) is also derived from the raw materials and fermentation process of Wogan oranges, but it showed a trend of first decreasing and then increasing. The contents were highest in W3 and W0, and the difference was not significant. This indicates that the flavor balance can be achieved through the synergistic regulation of peel and fermentation under different treatment conditions.

[0114] To investigate the effect of peel removal rate on the characteristic aroma compounds of Wogan orange wine (the results are as follows) Figures 8A-8B As shown), based on the volatile aroma compound data of four sets of Wogan orange wine, a partial least squares discriminant analysis model (PLS-DA) was constructed. Figure 8A The results showed that different peel removal rates in the treatment of Wogan orange wine exhibited significant spatial separation. The groups fermented with peel (W1, W2, W3) clustered in the right quadrant of the Component 1 (69.6%)-Component 2 (19.7%) plane, significantly different from the fully peeled group (W0), indicating that different peel removal rates can effectively alter the flavor characteristics of Wogan orange wine. Furthermore, the PLS-DA variable projection importance (VIP) value was used to evaluate the discriminative contribution of volatile flavor components, with VIP≥1 as the discrimination criterion to screen potential key biomarkers that significantly contributed to the differences between groups.

[0115] This study screened out 59 aroma components with a VIP ≥ 1. The selection was based on a dual screening criterion of VIP ≥ 1 and OAV ≥ 1 (W0-W3). Figure 8BThree key differential aroma components were identified: D-limonene, octanoic acid, and ethyl octanoate. The content of D-limonene was mainly regulated by the peel content, showing a significant linear increase (≥90-fold) as the peel removal rate decreased. The contents of octanoic acid and ethyl octanoate decreased significantly in W3 due to fermentation inhibition, but still showed significant increases of 27.23%–110.16% in W1–W2. In the peel-fermented groups (W1–W3), a dual screening criterion of VIP≥1 and OAV≥1 was used. Figure 8B Seven characteristic aroma components were screened out: β-myrcene (citrus fruit aroma), 2-methyl-3-buten-2-ol, 3,3-dimethylallylol (sweet and fruity aroma), linalool (chamomile aroma), anethole (vegetarian aroma), α-terpineol (floral and fruity aroma), and eugenol (clove aroma). All of these components showed a significant increasing trend with decreasing peel removal rate (e.g., ...). Figure 7 As shown (P < 0.05), the contents of β-myrcene, α-terpineol, and eugenol increased by more than 30 times compared to W0, indicating that fermentation with peel had the most significant impact on their content increase. These 10 substances can be used to effectively distinguish the aroma characteristics of fermented Wogan orange wine with peel from the fully peeled control group W0, and significantly enhance the complexity of the wine's aroma.

[0116] In contrast, in the fully peeled fermented sample W0, two characteristic aroma components, isobutanol (solvent odor) and phenylethyl alcohol (floral and fruity aroma), were identified using the same screening strategy (VIP≥1 and OAV≥1). Both substances showed a significant decreasing trend with decreasing peel removal rate (e.g., ...). Figure 7 As shown (P < 0.05), the fermented wine samples with skins showed significant reductions of 21.90%–87.22% and 44.82%–65.53% compared to W0, respectively.

[0117] The above results indicate that regulating the peel removal rate can alter the content of Wogan mandarin orange raw materials and fermentation aroma substances, thereby regulating the flavor of the wine sample, which can provide a theoretical basis for targeted regulation of the flavor and quality of Wogan mandarin orange wine.

[0118] 7. Sensory Evaluation Analysis of Wogan Orange Wine

[0119] Testing Method: Sensory evaluation was based on quantitative descriptive analysis (QDA). First, an evaluation panel was formed, consisting of 9 professional wine tasters (with ≥3 years of experience) selected according to GB / T 16291.1-2012. 14Subsequently, two national-level wine judges, referring to GB / T15038-2006 and ISO 11035 standards and considering the characteristics of Wogan orange wine, developed a standardized sensory description vocabulary, ultimately selecting eight core indicators: overall evaluation, clarity and color, aroma intensity, aroma complexity, taste quality, structure and harmony, style and typicality, and likability. Before the experiment began, the Williams equilibrium method was used to design a sample presentation sequence, with the reference sample and three randomly coded blind samples forming the test group. To eliminate the order effect, after tasting, the sample was spat out, and the mouth was rinsed with warm water. After resting for 15 minutes, the next group of tastings was conducted. Judges, who had undergone standardized training, performed quantitative descriptive analysis on Wogan orange wines with different peel removal rates according to the evaluation form. Sensory intensity was quantified using a 10-point gradient scale system (0-9 points), where 0 points indicated that the attribute was not detected, and 9 points corresponded to the highest intensity of perception. Finally, all scores were summarized, and the results were represented by a radar chart.

[0120] Test results are as follows Figure 9 As shown.

[0121] Sensory evaluation results based on quantitative descriptive analysis (QDA) show that ( Figure 9 The Wogan mandarin orange wine samples with different peel removal rates showed significant differences in sensory characteristics (W3 was not included in the analysis due to incomplete fermentation). W1 was significantly better than W2 in five indicators: overall evaluation, clarity and color, taste quality, structure and harmony, and preference (P < 0.05). W2, due to retaining a higher proportion of peel, significantly enriched typical Wogan mandarin orange flavor compounds, including terpenes, thus showing advantages in aroma intensity, aroma complexity, and style and typicality. However, W2 had a bitter taste, which affected its scores in overall evaluation and preference to some extent. In contrast, W0, due to the complete removal of peel, lacked the flavor precursors unique to citrus raw materials. Its flavor was dominated by fermentation ester aromas, and its overall aroma characteristics tended to be simple, lacking typical citrus notes. Therefore, its scores in all indicators were significantly lower than W1 (lower by 13.41% to 30.49%, P < 0.05). Based on the above sensory results, the peel matrix is ​​indispensable for the formation of the characteristic flavor of Wogan oranges, and the wine sample obtained by fermentation under the condition of controlling 80% peel removal rate has the most advantages in overall sensory performance.

[0122] Summarize:

[0123] This study analyzed key indicators such as the quality characteristics of Wogan mandarin orange juice, fermentation process, physicochemical indicators of the raw wine, color characteristics, volatile aroma components, and sensory quality. It comprehensively revealed the regulatory mechanism of peel removal rate on the quality of Wogan mandarin orange wine. The results showed that:

[0124] 1. The peel removal rate is significantly positively correlated with the juice yield. When the peel removal rate is ≥80%, it can effectively eliminate the inhibitory effect of the peel on the fermentation process while maintaining a high juice yield.

[0125] 2. The sugar and acid content of Wogan mandarin orange juice is not significantly affected by the peel removal rate; retaining the peel enhances the juice's translucency and yellow-green hue. Analysis of the wine shows that fermentation with the peel significantly increases the wine's translucency and yellow-green hue, but also promotes the accumulation of acids. Attention should be paid to the risk of excessive volatile acidity caused by excessive peel.

[0126] 3. The peel removal rate has a significant impact on the types and contents of volatile aroma substances in Wogan juice and Wogan wine, especially on the regulation of terpenoids. The terpenoid content of Wogan juice with peel was 48.15 to 234.93 times higher than that of the control group, and that of Wogan wine with peel was 22.28 to 91.88 times higher than that of the control group, highlighting that the peel is the key source of the typical aroma of Wogan.

[0127] 4. Different peel removal rates significantly affected the nine key aroma compounds in the raw wine (all four wine samples showed OAV≥1). 80% peel removal effectively preserved the content of inherent aroma compounds such as D-limonene, n-octanol, and (1R,5R)-carvacrol, promoted the accumulation of fermentation secondary metabolites with pleasant sensory properties, such as ethyl octanoate and octanoic acid, and effectively inhibited the excessive accumulation of negative flavor compounds such as isovaleric acid. Based on the dual threshold screening criteria of VIP≥1 and OAV≥1, D-limonene, octanoic acid, ethyl octanoate, β-myrcene, 2-methyl-3-buten-2-ol, 3,3-dimethylallylol, linalool, anisole, α-terpineol, and eugenol were identified as characteristic aroma compounds of Wogan orange wine fermented with peel; isobutanol and phenylethyl alcohol were identified as characteristic aroma compounds of wine fermented with peel.

[0128] 5. Sensory evaluation results further verified the key role of peel in the quality of Wogan orange wine. The wine sample with 80% peel removed was significantly better than other wine samples in five sensory indicators: overall evaluation, clarity and color, taste quality, structure and harmony, and likability.

[0129] 6. The self-selected brewing yeast was applied to the brewing of Wogan orange wine with peel. The resulting Wogan orange wine was of higher quality than that brewed with other yeasts, proving that the selected yeast has a significant impact on the quality of the fruit wine.

[0130] 7. Adding naringinase to the juice hydrolysis clarification step can further promote and optimize the color, aroma and flavor of the wine, so that the fruit wine retains the citrus flavor, significantly reduces the bitterness of the final Wogan wine, and improves the roundness and pleasantness of the taste as well as the clarity of the wine.

[0131] In summary, adjusting the peel removal rate can effectively alter the aroma composition and sensory quality of Wogan orange wine. An 80% peel removal rate is the optimal fermentation condition in this study, balancing fermentation efficiency, flavor complexity, and product acceptability. Furthermore, the use of self-selected Saccharomyces cerevisiae YQMSF2-4 ensures the wine maintains a harmonious aroma, luster, and balanced taste, possessing the characteristic style of this product. This effectively preserves the citrus flavor while avoiding bitterness from the peel, thus solving the technical problem of unsatisfactory flavor resulting from peel removal during fermentation of citrus fruit wines in existing technologies.

[0132] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is obvious that many changes and variations can be made based on the above teachings. Although embodiments of the invention have been shown and described, these specific embodiments are merely explanations of the invention and are not intended to limit it. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of the invention and its practical application, so that those skilled in the art, after reading this specification, can make modifications, substitutions, variations, and various choices and changes to the embodiments as needed without departing from the principles and spirit of the invention, provided that such modifications, substitutions, variations, and choices and changes are within the scope of the claims of the invention and are protected by patent law.

Claims

1. A method for preparing a peel-fermented Citrus sinensis wine, comprising the following steps S1: raw material pretreatment, enzymatic hydrolysis and clarification: juice is extracted from partially peeled Citrus sinensis, and a pectinase preparation is added to the juice, and the mixture is treated in a water bath at 35-45℃ for 2-3 h; S2: sulfur treatment: potassium metabisulfite is added and stirred evenly at 35-45℃; S3: yeast inoculation: a yeast with a bitter taste suppressing property is selected and optimized, and the yeast is inoculated into pre-activated yeast at 1×10^6 CFU / mL; S4: main fermentation: constant temperature fermentation at 22-30℃, and terminated when the residual sugar is ≤4 g / L; S5: post-treatment: cold stabilization and clarification at 0-10℃ for 7 d, separation of the supernatant, and finally obtaining the Citrus sinensis wine.

2. The fermented citrus wine with peel according to claim 1, and a method for preparing the same, characterized in that, The yeast used in the step S3 is Saccharomyces cerevisiae Saccharomyces cerevisiae ) YQMSF2-4, deposited on May 24, 2024, at the Guangdong Microbial Culture Collection Center (GDMCC), located at 100, Martyr's Road, Guangzhou, Guangdong Academy of Microbiology Institute, with the accession number GDMCC No: 64680.

3. The peel-in fermentation of Voviferous Citrus fruit wine and its preparation method according to claim 1, characterized in that, In the step S1, the juice is extracted from Citrus sinensis with a peel removal rate of 80%-100%.

4. The peel-in fermentation of Voviferous Citrus sinensis wine and its preparation method according to claim 1, characterized in that, In the step S1, the juice is extracted from Citrus sinensis with a peel removal rate of 80%.

5. The peel-in fermentation of Voviferous Citrus sinensis wine and its preparation method according to claim 1, characterized in that, In the step S2, the amount of potassium metabisulfite added is 100 mg / L.

6. The peel-in fermentation of Voviferous Citrus sinensis wine and its preparation method according to claim 1, characterized in that, In the step S1, the enzyme preparation includes one or both of pectinase added at 100 mg / L and naringinase added at 200 mg / L.

7. The peel-in fermentation of Voviferous Citrus sinensis wine and its preparation method according to claim 1, characterized in that, In the step S3, before inoculating the yeast, the yeast is added to a glucose solution with a concentration of 5% and pre-activated at 30℃ for 30 min. 8.A peel-fermented Citrus sinensis wine prepared by the method for preparing a peel-fermented Citrus sinensis wine. 9.Use of Saccharomyces cerevisiae YQMSF2-4 in peel-fermented Citrus sinensis wine.

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