Method for removing fishy smell of chicken gizzards through multi-bacterium combined fermentation

Abstract

The invention discloses a method for removing the fishy smell of chicken gizzards through multi-bacterium combined fermentation, and belongs to the technical field of poultry byproduct processing. According to the method disclosed by the invention, the chicken gizzards are subjected to fishy smell removal treatment by compounding the saccharomycetes Y4-1 and the bacillus SB. After fishy smell removal treatment, the content of key fishy smell substances including 1-octylene-3-alcohol, octanol, hexanal, nonanal and heptanal is greatly reduced, the total content is reduced from 25.15 mu g / g to 6.02 mu g / g and is reduced by 76.06%, heptanol, geranyl acetone, methyl heptanoate, methyl caprylate, glycerol monooleate, trans-2-decenal, 2-undecenal and other substances are completely removed, and the content of the key fishy smell substances is reduced by 76.06%. Meanwhile, elegant aroma components such as benzaldehyde and phenylacetaldehyde are generated. In conclusion, the saccharomycetes Y4-1 and the bacillus SB are compounded to remove fishy smell, so that the fishy smell substances of the chicken gizzards can be effectively removed, the flavor of the chicken gizzards can be further improved, and the edible value of the chicken gizzards is improved.

Description

Technical Field

[0001] This invention relates to the field of poultry by-product processing technology, and in particular to a method for removing the fishy smell from chicken gizzards through multi-strain co-fermentation. Background Technology

[0002] Poultry offal is rich in nutrients and bioactive substances beneficial to the human body, such as proteins, polysaccharides, fats, vitamins, and minerals like iron, zinc, and selenium. However, due to the strong fishy smell of most poultry offal, its utilization rate and added value are low, leading to the accumulation of a large amount of offal and resulting in resource waste. Common fishy-smelling substances in poultry offal include enols, enaldehydes, thiols, low-molecular-weight acids, amines, aldehydes, and heterocyclic compounds, among which the main fishy-smelling substances include hexanal, nonanal, 1-octen-3-one, 1-octen-3 alcohol, and trimethylamine. The fishy smell of poultry offal originates from many sources. Firstly, the offal itself produces a fishy smell; some parts naturally contain volatile fishy-smelling substances and unpleasant flavors. In addition, during storage, poultry offal is prone to protein degradation, fat oxidation, and enzymatic reactions of some substances, producing fishy-smelling substances or precursors. Secondly, the processing of poultry offal produces a fishy odor. Poultry offal undergoes oxidation and reduction reactions during both heat and non-heat processing (irradiation, sound waves, microwaves, ultra-high pressure) to generate volatile flavor compounds. Therefore, effectively removing the fishy odor from poultry offal has become a pressing issue in the poultry offal processing industry.

[0003] For the removal of the gamey odor from poultry offal, scholars both domestically and internationally have developed various methods, including physical, chemical, and biological methods. Physical methods mainly include sensory masking, adsorption, irradiation, and encapsulation / microencapsulation. Physical methods are the simplest and most commonly used, however, their effectiveness is not as good as chemical or biological methods. Chemical methods mainly include acid-base-salt treatment, antioxidant methods, oxidant methods, and Maillard reactions. Chemical deodorization is fast and effective, but it can easily leave chemical residues and cause food safety issues. Biological deodorization does not introduce other additives or chemicals, posing no harm to the human body. Microbial fermentation not only effectively reduces unpleasant flavors in fermented products but also infuses them with unique and pleasant flavors, thereby improving the overall flavor value of the food. Summary of the Invention

[0004] The purpose of this invention is to provide a method for removing the fishy smell of chicken gizzards through multi-strain co-fermentation, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] In a first aspect, the present invention provides a method for removing the fishy odor from chicken gizzards through multi-strain co-fermentation, comprising the following steps:

[0007] Take pretreated chicken gizzards and add mixed bacterial solution at a ratio of 1g:(2-6)mL. Ferment at a temperature of 20-40℃ for 4.5-6.5h to remove the fishy smell from the chicken gizzards.

[0008] The mixed bacterial solution was obtained by mixing Bacillus SB and yeast Y4-1.

[0009] Preferably, the volume ratio of Bacillus SB to yeast Y4-1 is 1:(1-3).

[0010] Preferably, the volume ratio of Bacillus SB to yeast Y4-1 is 1:3.

[0011] Preferably, the mixed bacterial solution is added at a ratio of 1g:4mL.

[0012] Preferably, the fermentation temperature is 30°C.

[0013] Preferably, the fermentation treatment time is 5.5 hours.

[0014] Preferably, the concentration of yeast Y4-1 in the mixed bacterial solution is 10. 7 -10 9 cfu / mL.

[0015] Preferably, the concentration of Bacillus SB in the mixed bacterial solution is 10. 7 -10 9 cfu / mL.

[0016] The present invention discloses the following technical effects:

[0017] This invention compares the deodorizing abilities of single-strain and multi-strain combinations to select a more effective multi-strain combination method for removing the fishy odor from chicken gizzards. From various combination methods, the combination of yeast Y4-1 and Bacillus SB was chosen as the most effective for deodorization. Single-factor experimental design and response surface methodology were used to optimize the combination conditions. Combined with practical operation, the optimal deodorization conditions were determined to be: a Bacillus SB cell concentration of 10... 7 cfu / mL, yeast Y4-1 cell concentration was 10 7 The mixture of Bacillus SB and Yeast Y4-1 at a volume ratio of 1:3 (cfu / mL) was fermented for 5.5 hours at a temperature of 30°C, with a material-to-liquid ratio of 1:4 (g / mL).

[0018] After deodorization treatment, the content of key odor-causing substances such as 1-octen-3-ol, octanol, hexanal, nonanal, and heptanal was significantly reduced, with the total content decreasing from 25.15 μg / g to 6.02 μg / g, a reduction of 76.06%. Heptanol, geranylacetone, methyl heptanate, methyl octanoate, glyceryl monooleate, trans-2-decenal, and 2-undecenal were completely removed. In particular, trans-2-decenal and 2-undecenal, which have a meaty flavor, were completely eliminated, while producing elegant aroma components such as benzaldehyde and phenylacetaldehyde. In summary, the deodorization method using a combination of yeast Y4-1 and Bacillus SB not only effectively removes the odor-causing substances from chicken gizzards but also further improves their flavor and enhances their edible value. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a diagram showing the deodorization effect of a single bacterium in Example 1;

[0021] Figure 2 This is a diagram showing the deodorizing effect of the multi-bacterial compound in Example 1;

[0022] Figure 3 This illustrates the effect of the strain ratio on the deodorization effect in Example 2.

[0023] Figure 4 The effects of different fermentation times (A), different fermentation temperatures (B), and different material-to-liquid ratios (C) on the deodorization effect in Example 2;

[0024] Figure 5 This is a three-dimensional response surface plot showing the effect of the interaction of various factors on the fishy smell of chicken gizzards in Example 3; where A is the effect of the interaction between fermentation time and fermentation temperature, B is the effect of the interaction between fermentation time and liquid-to-material ratio, and C is the effect of the interaction between fermentation temperature and liquid-to-material ratio.

[0025] Figure 6 This is a stacked bar graph showing the number of compounds of each category detected before and after deodorization in Example 4;

[0026] Figure 7 The changes in the content of key odor substances before and after deodorization in Example 4 are shown. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0030] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified. Yeast Y4-1, yeast Y12-2, lactic acid bacteria 6001, lactic acid bacteria 21790, Bacillus SA, and Bacillus SB were all obtained from the laboratory of the School of Food and Health, Beijing Technology and Business University. Among them, lactic acid bacteria 6001 and lactic acid bacteria 21790 have been disclosed in the literature "Synergistic improvement of hydrolyzed vegetable protein quality and flavor enhancement through multi-microbialfermentation and acid hydrolysis[J].(Wang Z,Cao Y,Fan M,Woldemariam KY,He X,Fan W,Liu Yingli*.LWT,2025,223.117729.https: / / doi.org / 10.1016 / j.lwt.2025.117729.)"; yeast Y4-1 and yeast Y12-2 have been disclosed in the literature "Antioxidant effect of yeast on lipid oxidation in salami sausage."(Liu Yingli,Cao Yating, Yohannes Woldemariam K, Zhong Shengjie, Yu Qinglin, Wang Jing. Frontiers in Microbiology, 2023, 13:1113848. https: / / doi.org / 10.3389 / fmicb.2022.1113848.) ; Bacillus SA and Bacillus SB have been published in the literature "Effects of cellulase-producing strains on the nutritional and soluble dietary fiber properties of whole wheat flour. (Yingli Liu, Shengjie Zhong, Maosi Fan, Zhengkai Wang, Min Cai, Xiaoming Wei, Jing Wang*. Food Science and Human Wellness, 2024, https: / / doi.org / 10.26599 / FSHW.2024.9250197.)".

[0033] Example 1: Test of Deodorization Ability of Single and Multi-Strain Fermentation

[0034] 1. Seed liquid preparation

[0035] Yeast, lactic acid bacteria, and Bacillus were activated on YPD, MRS, and LB agar plates, respectively. Yeast was cultured at 28°C for 24 hours, while lactic acid bacteria and Bacillus were cultured at 37°C for 24 hours. After obtaining single colonies, these colonies were inoculated onto new YPD, MRS, and LB agar plates. The yeast colonies were cultured at 28°C for 24 hours, and the lactic acid bacteria and Bacillus were cultured at 37°C for 24 hours to obtain single colonies. These single colonies were then inoculated into liquid culture medium and cultured on a shaker for 24 hours. After activation, the cultures were inoculated into suitable culture media and expanded until the yeast cell count reached 10⁻⁶. 8 cfu / mL, lactic acid bacteria count reaches 10 9 cfu / mL, Bacillus count reached 10 9 The bacterial cells were collected at cfu / mL and centrifuged at 6000 r / min and 4℃ for 10 min. An equal volume of sterile water was then added to the collected cells for later use.

[0036] 2. Sample pretreatment

[0037] Clean the chicken gizzards thoroughly, drain them, and slice them. Accurately weigh 20g of chicken gizzards and place them into 250mL Erlenmeyer flasks.

[0038] 3. Deodorizing effect of single-strain fermentation on chicken gizzards

[0039] Add 80 mL of sterile water to each conical flask at a material-to-liquid ratio of 1:4 (g / mL) and dilute to a concentration of 10. 7 A mixture of cfu / mL yeast Y4-1, yeast Y12-2, lactic acid bacteria 6001, lactic acid bacteria 21790, Bacillus SA, and Bacillus SB was prepared and labeled. The same amount of distilled water was added as a control group. The mixture was sealed and fermented at 30°C for 6 hours.

[0040] 4. Multi-strain fermentation effectively removes the fishy smell from chicken gizzards.

[0041] Yeast Y4-1, yeast Y12-2, lactic acid bacteria 6001, lactic acid bacteria 21790, Bacillus SA, and Bacillus SB were diluted with sterile water to a concentration of 10. 7The cfu / mL was mixed with four other different bacterial strains at a volume ratio of 1:1, resulting in twelve mixed bacterial groups, including Y4-1+6001, Y4-1+21790, Y4-1+SA, Y4-1+SB, Y12-2+6001, Y12-2+21790, Y12-2+SA, Y12-2+SB, 6001+SA, 6001+SB, 21790+SA, and 21790+SB.

[0042] Add 80 mL of the prepared bacterial solution to each of the 12 groups at a material-to-liquid ratio of 1:4 (g / mL), and label them. Use the group with the same amount of distilled water as the control group. After sealing, ferment at 30℃ for 6 hours.

[0043] 5. Analytical Methods

[0044] The odor of fermented chicken gizzards was scored by 20 trained professionals according to GB / T 10220 General Methodology for Sensory Analysis. The odor intensity was assessed on a 5-point scale. Evaluation team members took breaks between evaluating different samples to alleviate olfactory fatigue.

[0045] 6. Results and Analysis

[0046] In the single-strain deodorization experiment, the chicken gizzard treated with yeast Y4-1 had a deodorization score of 2.325, lower than other strains, indicating the best deodorization effect. This may be due to two reasons: firstly, yeast Y4-1 has a loose and porous structure, which can adsorb the fishy odor substances in the chicken gizzard; secondly, yeast Y4-1 can react with certain fishy odor substances as substrates during fermentation, thus achieving the deodorization effect. Lactic acid bacteria 21790 had a fishy odor score of 3.35, showing the worst deodorization effect. Yeast Y12-2, Bacillus SB, Lactic acid bacteria 6001, and Bacillus SA showed deodorization effects between the two, with no significant difference in deodorization effects between Lactic acid bacteria 6001 and Bacillus SA. Figure 1 Therefore, it can be concluded that yeast Y4-1 has the best deodorizing effect among single strains.

[0047] In the multi-strain deodorization experiment, the chicken gizzards treated with a compound bacterial solution of yeast Y4-1 and Bacillus SB had a fishy smell score of 1.5, which was lower than the fishy smell scores of chicken gizzards treated with other compound bacterial solutions, indicating that it had the best deodorization effect. Furthermore, the deodorization effect of this combination of two bacteria was better than that of either used alone, suggesting a synergistic effect during fermentation. In contrast, the fishy smell score of the compound bacterial solution of yeast Y12-2 and lactic acid bacteria 21790 was 2.875, showing the worst deodorization effect among all the compound solutions. The deodorization effects of other compound bacterial solutions were between the two mentioned above, and the effects of the compound bacterial solution treatment groups were significantly different from the control group. In addition, the fishy smell scores of chicken gizzards treated with the compound bacterial solution were all below 3, further demonstrating the significant deodorization effect of the compound bacterial solution. Figure 2 ).

[0048] Comparing the deodorization effects of single-strain and multi-strain combinations, the lowest deodorization score for single-strain was 2.325. Scores between 1.5 and 2.0 accounted for 0%, scores between 2.0 and 2.5 accounted for 16.7%, scores between 2.5 and 3.0 accounted for 66.7%, and scores between 3.0 and 3.5 accounted for 16.7%. For multi-strain combinations, the lowest deodorization score was 1.5. Scores between 1.5 and 2.0 accounted for 33.3%, scores between 2.0 and 2.5 accounted for 16.7%, scores between 2.5 and 3.0 accounted for 50%, and scores between 3.0 and 3.5 accounted for 0%. Overall, the deodorization effect of multi-strain combinations is superior to that of single-strain methods. Therefore, this invention uses a multi-strain combination method to deodorize chicken gizzards.

[0049] Example 2: Single-factor experimental design of chicken gizzard deodorization process parameters

[0050] 1. Effect of strain ratio on deodorization effect

[0051] Accurately weigh 20g of cleaned chicken gizzards into a 250mL Erlenmeyer flask. Set the material-to-liquid ratio to 1:4 (g / mL), fermentation time to 6 hours, and fermentation temperature to 30℃. Dilute Bacillus SB and yeast Y4-1 separately with sterile water to a concentration of 10. 7 The compound bacterial solution was added to an Erlenmeyer flask at a volume ratio of 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, and 4:1, and mixed. After sealing, the mixture was fermented. The fishy smell of chicken gizzards was used as an indicator for sensory evaluation to explore the effect of the strain ratio on the deodorization effect.

[0052] 2. The effect of fermentation temperature on deodorization effect

[0053] Bacillus SB and yeast Y4-1 were diluted separately with sterile water to a concentration of 10. 7 20g of cleaned chicken gizzards were accurately weighed into a 250mL Erlenmeyer flask. The material-to-liquid ratio was set at 1:4 (g / mL), the fermentation time at 6h, and the volume ratio of Bacillus SB to yeast Y4-1 at 1:3. 80mL of a compound bacterial solution of yeast Y4-1 and Bacillus SB was added to the Erlenmeyer flask and mixed. After sealing, the mixture was fermented at 20℃, 25℃, 30℃, 35℃, and 40℃. Sensory evaluation was performed using the fishy smell of the chicken gizzards as an indicator to explore the effect of fermentation temperature on the deodorization effect.

[0054] 3. The effect of the material-to-liquid ratio on the deodorization effect

[0055] Bacillus SB and yeast Y4-1 were diluted separately with sterile water to a concentration of 10. 7 Accurately weigh 20g of cleaned chicken gizzards into a 250mL Erlenmeyer flask. Set the fermentation temperature to 30℃, fermentation time to 6h, and Bacillus SB to yeast Y4-1 volume ratio to 1:3. Add 20mL, 40mL, 60mL, 80mL, and 100mL of the compound bacterial solution to the Erlenmeyer flasks at material-to-liquid ratios of 1:1 (g / mL), 1:2 (g / mL), 1:3 (g / mL), 1:4 (g / mL), and 1:5 (g / mL), respectively, mix, seal, and ferment. Use the fishy smell of chicken gizzards as an indicator to conduct sensory evaluation and explore the effect of material-to-liquid ratio on the deodorization effect.

[0056] 4. The effect of fermentation time on deodorization effect

[0057] Bacillus SB and yeast Y4-1 were diluted separately with sterile water to a concentration of 10. 7 Accurately weigh 20g of cleaned chicken gizzards into a 250mL Erlenmeyer flask. Set the material-to-liquid ratio to 1:4 (g / mL), the fermentation temperature to 30℃, and the volume ratio of Bacillus SB to Yeast Y4-1 to 1:3. Add 80mL of the compound bacterial solution to the Erlenmeyer flask and mix. After sealing, ferment for 0h, 2h, 4h, 6h, and 8h respectively. Use the fishy smell of chicken gizzards as an indicator to conduct sensory evaluation and explore the effect of fermentation time on the deodorization effect.

[0058] 5. Analytical Methods

[0059] The odor of fermented chicken gizzards was scored by 20 trained professionals according to GB / T 10220 General Methodology for Sensory Analysis. The odor intensity was assessed on a 5-point scale. Evaluation team members took breaks between evaluating different samples to alleviate olfactory fatigue.

[0060] 6. Results and Analysis

[0061] 6.1 Effect of strain ratio on deodorization of chicken gizzards

[0062] The intensity of the fishy smell in chicken gizzards first decreased and then increased with the increase of the ratio of Bacillus SB to yeast Y4-1. When the volume ratio of Bacillus SB to yeast Y4-1 was 1:3, the sensory score was the lowest, the intensity of the fishy smell in the chicken gizzards was the lowest, and the deodorization effect was the best. Figure 3 ).

[0063] 6.2 Effect of fermentation temperature on the deodorization effect of chicken gizzards

[0064] The intensity of the fishy smell of chicken gizzards first decreased and then increased with increasing fermentation temperature. The sensory score was lowest at 30℃, indicating the lowest intensity of the fishy smell in the chicken gizzards. Figure 4 (B) Both excessively high and low temperatures can affect the activity of yeast and Bacillus. A suitable fermentation temperature can improve the fermentation efficiency of yeast and Bacillus, thereby enhancing the deodorization effect.

[0065] 6.3 Effect of feed-to-liquid ratio on the deodorization effect of chicken gizzards

[0066] The intensity of the fishy smell of chicken gizzards first decreased and then increased with the increase of the feed-to-liquid ratio. When the feed-to-liquid ratio was 1:4 (g / mL), the sensory score was the lowest, and the intensity of the fishy smell of the chicken gizzards was the lowest. Figure 4 In addition to increasing the amount of bacterial solution, the fermentation efficiency can be improved, thereby improving the deodorization effect. However, if the amount of bacterial solution is too high, the off-odor of yeast and Bacillus will remain on the chicken gizzard sample, and excessive acid production by yeast will also produce an unpleasant odor.

[0067] 6.4 Effect of fermentation time on the deodorization effect of chicken gizzards

[0068] The intensity of the fishy smell of chicken gizzards first decreased and then increased with increasing fermentation time. The sensory score was lowest when the fermentation time was 6 hours, indicating the lowest intensity of the fishy smell in the chicken gizzards. Figure 4 (A) If the fermentation time is too long, new fishy-smelling substances may be produced under the action of miscellaneous bacteria, thereby reducing the deodorization effect.

[0069] The optimal deodorization effect was achieved when the volume ratio of Bacillus SB to yeast Y4-1 was 1:3, the fermentation temperature was 30℃, the fermentation time was 6h, and the material-to-liquid ratio was 1:4 (g / mL). Therefore, response surface methodology was conducted at fermentation temperatures of 25℃, 30℃, and 35℃, fermentation times of 4h, 6h, and 8h, and material-to-liquid ratios of 1:3 (g / mL), 1:4 (g / mL), and 1:5 (g / mL).

[0070] Example 3: Experimental Design for Response Surface Analysis of Chicken Gizzard Deodorization Process Parameters

[0071] Based on the results of the single-factor experiments, three factors that significantly influenced the sensory evaluation of chicken gizzard odor were selected as independent variables, and the sensory evaluation result (Y) was selected as the response value. A three-factor, three-level experimental design was conducted, and the optimal process parameters for removing the chicken gizzard odor were obtained through analysis. The factors and levels are shown in Table 1.

[0072] Table 1. Experimental Factors and Levels of Response Surface Methodology

[0073]

[0074] Results and Analysis:

[0075] Based on the results of the single-factor experiments, three factors that significantly influenced the sensory evaluation of the fishy smell of chicken gizzards—fermentation time (A), fermentation temperature (B), and liquid-to-material ratio (C)—were selected as independent variables for response surface methodology (RSM). Table 2 shows the RSM experimental design and results, and Table 3 shows the results of the analysis of variance (ANOVA). Based on the RSM experimental results, the quadratic polynomial regression model equation was obtained: Y = 0.94 + 0.4875A - 0.0625B + 0.05C + 0.075AC + 0.125BC + 0.88A 2 +0.93B 2 +0.905C 2 .

[0076] Table 3 shows that the model's p-value is <0.0001, indicating that the model is highly significant, while the lack-of-fit term is not significant, suggesting that the equation fits well, has no obvious error, and is of good reliability. R 2 =0.9956, indicating a high correlation between the actual and predicted values, R = 2 Adj =0.9900 and R 2 Pred =0.9853, the difference is less than 0.2. Therefore, this model can reflect the relationship between each parameter and the response value in the chicken gizzard odor removal process relatively well, thus predicting the optimal odor removal conditions. Table 3 also shows that the first-order term A of the equation has a highly significant impact on the odor removal effect, while B and C have no significant impact. The quadratic term A... 2 B 2 C 2 All factors were highly significant, with the interaction terms BC having a significant effect, while AB and AC had no significant effect. The order of influence of each factor on the deodorization effect of chicken gizzards was A>B>C, i.e., fermentation time>fermentation temperature>material-to-liquid ratio.

[0077] Design-Expert 13 was used to create contour plots and response surface plots. The response surface plot and contour plot show the interaction between two factors. The shape of the contour lines indicates the strength of the interaction; ellipses indicate a significant interaction, while circles indicate an insignificant interaction. The steepness of the response surface slope also reflects the degree of influence on the response value; the steeper the slope, the stronger the influence. The elliptical shape of contour line BC indicates a significant interaction between fermentation temperature and liquid-to-material ratio (P<0.05). The circular shapes of contour lines AB and AC indicate that the interaction between fermentation time and fermentation temperature / liquid-to-material ratio is insignificant (P>0.05). The factor with the greatest impact on deodorization is fermentation time, followed by fermentation temperature, and the least influential factor is the liquid-to-material ratio. Figure 5 (AC).

[0078] Based on the response surface methodology results, the experimental data were optimized and predicted. The optimal deodorization process parameters for chicken gizzards were found to be a fermentation time of 5.45 h, a fermentation temperature of 30.18 ℃, and a liquid-to-solid ratio of 3.98 mL / g. Under these conditions, the predicted sensory score for chicken gizzards was 0.87. Considering practical operation, the optimal process parameters were adjusted to a fermentation time of 5.5 h, a fermentation temperature of 30 ℃, and a liquid-to-solid ratio of 1:4 (g / mL). The measured sensory score for the fishy smell of the chicken gizzards was 0.8, which is close to the model's predicted value, indicating that the model can be used to optimize the deodorization process for chicken gizzards.

[0079] Table 2 Results of response surface methodology for removing the fishy smell from chicken gizzards

[0080]

[0081]

[0082] Table 3. Analysis of Variance in Response Surface Experiments

[0083]

[0084] Example 4: Changes in volatile flavor compounds under optimal process conditions

[0085] Accurately weigh 2g of crushed chicken gizzard sample into a 20mL headspace vial, seal and place. Each sample group is measured three times. The sample is pretreated by SPME. The sample is heated at 55℃ for 15min, and the aged extraction needle is inserted into the headspace vial to adsorb VOCs in the sample at 55℃ for 30min.

[0086] GC conditions: TG-WaxMS polar column (30m × 0.25mm, 0.25μm), helium as carrier gas, flow rate 1.0mL / min. Temperature program: initial temperature 40℃, held for 4 minutes, then increased to 230℃ at a rate of 4℃ / min, held for 10 minutes.

[0087] MS conditions: The ion source was an electron impact source (EI), with an electron energy of 70 eV, a temperature of 230 °C, an emission current of 200 μA, an ion source temperature of 300 °C, and a scan range of 35-350 m / z.

[0088] The measured sample spectra were compared with those obtained from the NIST 2020 spectral library for qualitative analysis. Volatile components with a matching degree greater than 700 were selected as qualitative results. 2-Methyl-3-heptanone was set as the internal standard, and the content of each volatile component was calculated by the ratio of the peak area of ​​the analyte to that of 2-methyl-3-heptanone in the sample.

[0089] The calculation formula is as follows:

[0090]

[0091] Where, A X A 2-甲基-3-庚酮 C represents the peak areas of the volatile component to be tested and the internal standard, respectively; 2-甲基-3-庚酮 V represents the mass concentration (mg / L) of the added internal standard. 2-甲基-3-庚酮 This indicates the volume of the added internal standard (20 μL); m k The mass of the added chicken gizzard sample (2g).

[0092] Results and Analysis:

[0093] Before deodorization, 29 volatile flavor compounds were detected in chicken gizzards, and after deodorization, 25 volatile flavor compounds were detected in chicken gizzards (see Table 4). The volatile flavor compounds in chicken gizzards mainly include alcohols, aldehydes, esters, ketones, acids, hydrocarbons, and other substances. Figure 6 After deodorization treatment, the content of most volatile flavor compounds is reduced, and the content of key fishy-smelling compounds 1-octen-3-ol, octanol, hexanal, nonanal, and heptanal is significantly reduced. Figure 7 The total content decreased from 25.15 μg / g to 6.02 μg / g, a reduction of 76.06%. Flavor compounds such as heptanol, geranylacetone, methyl heptanate, methyl octanoate, glyceryl monooleate, trans-2-decenal, and 2-undecenal were completely removed. However, during the deodorization process, flavor compounds such as benzaldehyde, phenylacetaldehyde, 2-nonanone, and 2-undecenone were also generated, possibly due to yeast fermentation.

[0094] Alcohols generally possess plant-like, aromatic, rancid, and earthy odors, and are generated from the oxidation and decomposition of unsaturated fats or the reduction of carbonyl compounds in chicken gizzards. After deodorization, the volatile alcohols detected in chicken gizzards are lower than those before deodorization, with less heptanol. Among the alcohols, 1-octen-3-ol has a significant impact on the formation of the fishy odor, providing the characteristic mushroom aroma of chicken gizzards; octanol also contributes to the fishy odor. Co-fermentation by yeast and Bacillus can transform or decompose the fishy substances, producing odorless substances.

[0095] Aldehydes have a low threshold for odor, and even small amounts can emit a strong fishy smell, significantly impacting its formation. Aldehydes are abundant in chicken gizzards, with hexanal, heptanal, nonanal, and decanal being particularly prevalent. After deodorization through combined fermentation with yeast and Bacillus, their levels are reduced, and the fishy smell is lessened.

[0096] Hydrocarbons have a relatively high threshold. Before deodorization, the content of hydrocarbons detected in chicken gizzards was low, except for heptane. Therefore, hydrocarbons have little impact on the fishy smell of chicken gizzards. However, there are many types of hydrocarbons, and some olefins can form ketones or aldehydes under certain conditions, increasing the fishy smell of chicken gizzards. After deodorization by combined fermentation with yeast and Bacillus, their contents decreased to varying degrees.

[0097] Esters generally have a pleasant aroma and can reduce the fishy smell, so they are not considered fishy odor components. Ketones have a high threshold and are not easily detected, so they have little impact on the fishy smell of chicken gizzards and are not considered fishy odor components either. Other substances are completely reacted into odorless substances after co-fermentation by yeast and Bacillus. This indicates that co-fermentation by yeast and Bacillus is effective in removing fishy odor components.

[0098] Table 4. Changes in the content of volatile flavor compounds in chicken gizzards before and after deodorization treatment.

[0099]

[0100]

[0101] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for removing the fishy odor from chicken gizzards through multi-strain co-fermentation, characterized in that, Includes the following steps: Take pretreated chicken gizzards and add mixed bacterial solution at a ratio of 1g:(2-6)mL. Ferment at a temperature of 20-40℃ for 4.5-6.5h to remove the fishy smell from the chicken gizzards. The mixed bacterial solution was obtained by mixing Bacillus SB and yeast Y4-1.

2. The method for removing the fishy smell from chicken gizzards according to claim 1, characterized in that, The volume ratio of the Bacillus SB to the yeast Y4-1 is 1:(1-3).

3. The method for removing the fishy smell from chicken gizzards according to claim 2, characterized in that, The volume ratio of Bacillus SB to yeast Y4-1 is 1:

3.

4. The method for removing the fishy smell from chicken gizzards according to claim 1, characterized in that, Add the mixed bacterial solution at a ratio of 1g:4mL.

5. The method for removing the fishy smell from chicken gizzards according to claim 1, characterized in that, The fermentation temperature is 30℃.

6. The method for removing the fishy smell from chicken gizzards according to claim 1, characterized in that, The fermentation process takes 5.5 hours.

7. The method for removing the fishy smell from chicken gizzards according to claim 2, characterized in that, In the mixed bacterial solution, the concentration of yeast Y4-1 is 10. 7 -10 9 cfu / mL.

8. The method for removing the fishy smell from chicken gizzards according to claim 2, characterized in that, In the mixed bacterial solution, the concentration of Bacillus SB is 10. 7 -10 9 cfu / mL.

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