Lactobacillus pentosus strain HY-1010, preparation method and application thereof

Abstract

The application relates to a lactobacillus pentosus strain HY-1010, a preparation method and application thereof, and belongs to the technical field of aquatic product processing. The lactobacillus pentosus strain HY-1010 is preserved in the China Center for Type Culture Collection on June 1, 2026, has a preservation number of CCTCC NO: M 20261153, and is classified and named as Lactiplantibacillus pentosus . The strain is screened from fish meat subjected to natural fermentation for 30 hours, has excellent growth performance and stable acid production, and can realize efficient deodorization of tilapia and bonito through 37 DEG C short-time anaerobic fermentation for 3 hours. Through triple verification of sensory evaluation, GC-MS and GC-IMS, the fish meat after fermentation has significantly reduced methyl mercaptan, triethylamine, volatile aldehydes, ketones, alkanes and other fishy substances, and significantly enriched acid, alcohol, ketone and ester aroma substances, and the flavor and sensory quality are significantly improved. The strain has high safety, wide application range, green and simple process, and is suitable for industrial production, and provides special microbial resources for deodorization of freshwater fish and seawater fish.

Description

Technical Field

[0001] This application relates to the field of aquatic product processing technology, and in particular to a strain of Lactobacillus pentosus HY-1010 and its preparation method and application. Background Technology

[0002] Tilapia is a major freshwater farmed fish in my country, characterized by large-scale farming, high yield, tender flesh, and high cost-effectiveness, making it widely used in the seafood processing industry. Skipjack tuna, a typical deep-sea fish, has high protein content and rich nutritional value, making it a core ingredient in canned goods and surimi products. However, both tilapia and skipjack tuna have significant drawbacks. Their flesh is rich in trimethylamine oxide and unsaturated fatty acids, which are easily degraded during storage and processing, producing trimethylamine, aldehydes, sulfur compounds, and other fishy-smelling substances. This results in a strong fishy odor and poor sensory quality, severely restricting the deep processing and market promotion of both types of fish.

[0003] Currently, methods for removing fishy odors from aquatic products are mainly divided into three categories: physical deodorization, chemical deodorization, and biological deodorization. Among them, physical deodorization is costly and incomplete; chemical deodorization easily leaves chemical residues, posing food safety risks; and microbial biological deodorization, with its safety, non-toxicity, good flavor improvement effect, and alignment with the concept of natural processing, has become the mainstream research direction for deodorizing aquatic products. Lactic acid bacteria are dominant beneficial bacteria in the natural fermentation process of fish, possessing the characteristics of producing acid to inhibit bacteria, degrading fishy substances, and generating aroma substances, making them a high-quality strain for deodorizing aquatic products.

[0004] In existing technologies, the types of lactic acid bacteria strains used for deodorizing fish are limited, mostly general-purpose *Lactobacillus plantarum* and *Lactobacillus sakei*. There are few strains specifically designed for deodorizing tilapia and skipjack tuna, and most of these strains exhibit poor growth performance and low deodorization efficiency. Naturally fermented tilapia contains a large number of adaptable native lactic acid bacteria. Screening for superior native *Lactobacillus pentosus* can specifically address the industry pain point of strong fishy odor in tilapia and skipjack tuna, which is of significant practical importance for promoting the upgrading of aquatic fermentation deodorization technology and improving the quality of aquatic products. Summary of the Invention

[0005] In view of this, this application provides a strain of Lactobacillus pentosus HY-1010, its preparation method and application. This strain has excellent growth performance and significant deodorization effect. It can be adapted to deodorization processing of both freshwater and saltwater fish, and can effectively overcome the shortcomings of existing technologies where tilapia and skipjack tuna have a strong fishy smell and lack dedicated deodorizing lactic acid bacteria, resulting in poor deodorization effect.

[0006] The first aspect of this application provides a strain of *Lactobacillus pentosaccharide* HY-1010, which was deposited at the China Center for Type Culture Collection (CCTCC) on June 1, 2026, with accession number CCTCC NO:M 20261153, and is classified as follows: Lactiplantibacillus pentosus .

[0007] Specifically, 16S rDNA gene sequencing was performed on Lactobacillus pentosus HY-1010, a phylogenetic tree was constructed, and the gene sequence alignment similarity reached 99.9%, confirming the strain as Lactobacillus pentosus, with accurate species identification.

[0008] A second aspect of this application also provides a method for preparing the above-mentioned Lactobacillus pentosus, comprising the following steps:

[0009] Fermentation liquid was added to fish meat and natural fermentation was carried out at a constant temperature of 37℃. Lactobacillus pentosus HY-1010 was isolated and screened.

[0010] Specifically, pH dynamic monitoring was conducted on the natural fermentation process of fish meat with added fermentation liquid. pH was measured at 0 h, 6 h, 12 h, 18 h, 24 h, and 30 h of fermentation. In the early stage of fermentation, the microbial community produced acid through metabolism, and the pH slowly decreased. In the later stage of fermentation, the pH tended to stabilize, providing a physicochemical basis for strain screening.

[0011] Preferably, the specific steps include:

[0012] S1. Collect tilapia meat that has been naturally fermented at 37℃ for 30 hours with added fermentation broth. Under aseptic conditions, remove the skin and bones, mince the fish meat using a meat grinder, accurately weigh the fish paste, and perform serial dilution with sterile physiological saline at a dilution gradient of 10. -5 ~10 -7 ;

[0013] S2. Different gradient dilutions were spread onto MRS solid medium and anaerobic cultured. Single colonies with clear calcium dissolution zones and regular colony morphology were picked and purified three times using the three-zone streak method to obtain Lactobacillus pentosus HY-1010.

[0014] The MRS solid culture medium formula is as follows: 10 g peptone, 10 g beef extract, 5 g yeast extract, 20 g glucose, 5 g sodium acetate, 2 g diammonium citrate, 1 mL Tween-80, 0.58 g MgSO4·7H2O, 0.25 g MnSO4·H2O, and 18 g agar. Distilled water is added to bring the volume to 1000 mL, and the pH of the culture medium is adjusted to 6.2~6.4.

[0015] Furthermore, the strain was propagated using MRS liquid medium, which does not contain agar, but whose other components, ratios, and pH conditions are completely identical to those of MRS solid medium. During the culture in MRS liquid medium, OD was measured. 600 The growth curve of the strain was plotted. The strain entered the logarithmic growth phase at 9 h and reached the stable growth phase at 24 h, showing strong cell reproduction ability. The strain has excellent temperature tolerance and can be adapted to the short-term anaerobic fermentation processing environment of fish meat at 37℃.

[0016] Preferably, in step S2, the anaerobic culture temperature is 30°C and the anaerobic culture time is 24~48 h.

[0017] Preferably, the fish meat is tilapia meat or bonito meat.

[0018] Preferably, the fermentation broth comprises the following components by mass percentage: 2 wt% sodium chloride, 2 wt% glucose, and the balance being sterile water. The fermentation broth is prepared by mixing sterile water, 2 wt% sodium chloride, and 2 wt% glucose, and the pH of the system is maintained naturally without adjustment.

[0019] The third aspect of this application also provides the application of the above-mentioned Lactobacillus pentosus HY-1010 in the preparation of a microbial deodorizing agent.

[0020] A fourth aspect of this application also provides a microbial deodorizing agent, wherein the microbial deodorizing agent comprises the aforementioned Lactobacillus pentosaceus, and the viable count is not less than 1 × 10⁻⁶. 9 CFU / mL.

[0021] The fifth aspect of this application also provides the application of the aforementioned microbial deodorizing agent in the fermentation and deodorization of food-grade aquatic products.

[0022] Compared with the prior art, this application has the following advantages:

[0023] (1) This application screened and obtained the native Lactobacillus pentosus HY-1010. The screening substrate was tilapia with added fermentation broth and natural fermentation for 30 hours. The strain has strong adaptability and high safety, and no biogenic amines are produced, which meets the food processing safety standards. The application of Lactobacillus pentosus HY-1010 provided in this application in the deodorization of tilapia and bonito meat shows that the strain can metabolize and degrade fishy substances such as methanethiol, triethylamine, aldehydes, ketones, and alkanes in fish meat, and at the same time synthesize aromatic substances such as acids, alcohols, ketones, and esters to optimize the flavor of fish meat.

[0024] (2) The fish meat fermentation deodorization method provided in this application is simple, green and pollution-free, does not require the addition of chemical deodorizing agents, is suitable for large-scale industrial production, has mild fermentation conditions, retains the fish meat nutrition to the maximum extent, and the fish meat has no odor and a pure fragrance after deodorization.

[0025] (3) This application adds dynamic pH monitoring throughout the natural fermentation process, combined with OD 600 Growth curves comprehensively characterize the physicochemical properties of the strains, showcasing short culture cycles, rapid reproduction rates, and low preparation costs for the bacterial agents.

[0026] (4) This application can simultaneously remove the fishy smell from tilapia and skipjack tuna, has a wide range of applications, and the fermentation process meets the requirements of aquatic product processing production;

[0027] (5) The deodorization effect of this application was comprehensively verified by sensory evaluation, GC-MS, and GC-IMS flavor fingerprint spectrum. The data are intuitive and reliable, the deodorization effect is significant, the degradation rate of fishy substances is high, and the aroma substances are significantly enriched. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a graph showing the pH change during the natural fermentation process of tilapia.

[0030] Figure 2 A photograph of the colony morphology of Lactobacillus pentosus HY-1010;

[0031] Figure 3 Lactobacillus pentosus HY-1010 OD 600 Growth curve;

[0032] Figure 4 Phylogenetic tree of Lactobacillus pentosus HY-1010 16S rDNA;

[0033] Figure 5 A statistical chart of sensory evaluation scores for fish meat;

[0034] Figure 6 GC-MS thermograms of volatile substances in fish meat before and after deodorization;

[0035] Figure 7 GC-IMS flavor fingerprint of tilapia flesh before and after deodorization;

[0036] Figure 8 GC-IMS flavor fingerprint of bonito flesh before and after deodorization. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0039] In the following examples and comparative examples, unless otherwise specified, all raw materials can be prepared by commercial purchase or conventional methods.

[0040] The MRS solid culture medium formula is as follows: 10 g peptone, 10 g beef extract, 5 g yeast extract, 20 g glucose, 5 g sodium acetate, 2 g diammonium citrate, 1 mL Tween-80, 0.58 g MgSO4·7H2O, 0.25 g MnSO4·H2O, and 18 g agar. Add distilled water to a final volume of 1000 mL and adjust the pH of the culture medium to 6.2-6.4.

[0041] The strain was propagated using MRS liquid medium, which does not contain agar, and whose other components, ratios, and pH conditions are completely identical to those of MRS solid medium.

[0042] The fermentation broth comprises the following components by mass percentage: 2 wt% sodium chloride, 2 wt% glucose, and the balance being sterile water. The fermentation broth is prepared by mixing sterile water, 2 wt% sodium chloride, and 2 wt% glucose, and the pH of the system is maintained naturally without adjustment.

[0043] Example 1: Isolation, screening and identification of Lactobacillus pentosus HY-1010

[0044] 1. Pretreatment of the substrate for strain isolation

[0045] Tilapia fillets were collected after being fermented with added fermentation broth at a constant temperature of 37℃ for 30 hours. Under aseptic conditions, the skin and bones were removed, and the fillets were minced using a meat grinder. 1.0g of the minced fish was accurately weighed and serially diluted with sterile physiological saline at a dilution gradient of 10. -5 ~10 -7 .

[0046] 2. Strains Isolation and Purification

[0047] Different gradient dilutions were spread onto MRS solid medium and anaerobic cultured at 30℃ for 48 h. Single colonies with clear calcium dissolution zones and regular colony morphology were picked and purified three times using the three-zone streak method to obtain a single pure strain, named HY-1010.

[0048] 3. Observation of colony morphology

[0049] The purified strain was inoculated onto MRS solid medium and anaerobically cultured at 30°C for 48 hours. Colony morphology was photographed; the colonies were milky white, round, smooth and moist, with a raised center and regular edges, and free from contamination by other microorganisms (e.g., ...). Figure 2 ).

[0050] 4. pH measurement during fermentation process

[0051] During the natural fermentation process of tilapia with added fermentation liquid, such as Figure 1 Samples were taken at regular intervals of 0 h, 6 h, 12 h, 18 h, 24 h, and 30 h during fermentation. The pH of the fermentation broth was measured using a precision pH meter, and each group was tested in triplicate.

[0052] The test results showed that in the early stage of fermentation (0-12 h), microorganisms multiplied and metabolized to produce organic acids, and the pH of the fermentation system slowly decreased from 6.85 to 5.42; in the middle stage of fermentation (12-24 h), the acid production rate slowed down and the pH fluctuated slightly; in the later stage of fermentation (24-30 h), the microbial community structure was stable and the pH was maintained at 4.95-5.10. The acidic environment can effectively inhibit the growth of putrefactive bacteria and provide a suitable environment for the growth and reproduction of Lactobacillus pentosus HY-1010.

[0053] 5. Determination of bacterial growth performance (OD) 600 )

[0054] Strain strain HY-1010 was inoculated into MRS liquid medium and cultured anaerobically at 30°C. Samples were taken every 6 hours, and the OD of the bacterial culture was measured using a UV spectrophotometer. 600 Absorbance values, plot growth curves (e.g.) Figure 3 The results showed that the strain was in a lag phase from 0 to 9 hours, a logarithmic growth phase from 9 to 24 hours, and entered a stationary phase after 24 hours, during which the bacterial concentration tended to stabilize, and the maximum OD value was [not specified]. 600 The value can reach 1.82, indicating that the strain has excellent growth and reproduction capabilities.

[0055] 6. Molecular biological identification of strains

[0056] DNA was extracted from the strain (as shown in SEQ ID NO.1), and the 16S rDNA gene sequence was amplified using universal bacterial primers 27F and 1492R. After sequencing, the sequence was aligned in the NCBI database, and a phylogenetic tree was constructed using the neighbor-joining method (as shown in SEQ ID NO.1). Figure 4 The results showed that strain HY-1010 had 100% homology with Lactobacillus pentosus, thus identifying the strain as Lactobacillus pentosus.

[0057] The sequence is as follows:

[0058]

[0059] Example 2: Preparation of deodorizing bacterial culture (incubated at 37°C)

[0060] 1. Activation culture of bacterial strain: Lactobacillus pentosus HY-1010 was streaked onto MRS solid medium and anaerobic cultured at 37℃ for 36h. Plump single colonies were picked and inoculated onto MRS liquid medium for expansion culture. In order to adapt to the fish meat inoculation deodorization test, the expanded bacterial solution was placed at a constant temperature of 37℃ for 6h to obtain a test bacterial solution with excellent activity.

[0061] 2. Pretreatment of bacterial culture: After the culture is completed, the bacterial concentration is adjusted with sterile physiological saline to prepare a highly active test bacterial culture for later use; the control group is replaced with an equal amount of sterile physiological saline.

[0062] 3. Preparation of experimental equipment: The sterile equipment used in this experiment includes: a beaker containing 75% alcohol, two beakers containing sterile physiological saline, sterile forceps, a sterile conical flask for placing the forceps, sterile petri dishes, sterile scalpels, sterile sample bags, sterile cotton swabs, kitchen paper, and sealing film. All equipment is sterilized by high temperature and high pressure before use to avoid contamination by other microorganisms.

[0063] Example 3: Pre-treatment and inoculation deodorization experiment of tilapia and skipjack tuna meat

[0064] 1. Raw material pretreatment: Select fresh tilapia and skipjack tuna. After slaughtering, immediately rinse the surface of the abdominal muscle with sterile distilled water to remove blood and impurities. Use sterile gauze to absorb the moisture on the surface of the fish meat. Use sterile knives to cut the abdominal muscle of the tilapia into uniform fish pieces of 2cm×2cm×1cm, with each piece weighing about 5g. Pack them into sterile sample bags.

[0065] 2. Surface disinfection treatment: Immerse the cut fish pieces in a 75% alcohol solution for 5 seconds to quickly kill the bacteria on the surface of the fish. Then remove the fish pieces and rinse them once with sterile saline to remove alcohol residue. Use sterile gauze to absorb the moisture on the surface of the fish.

[0066] 3. Low-temperature precooling: Place the disinfected and dried fish pieces in a 4℃ refrigerator for 30 minutes to precool them, so that the overall temperature of the fish pieces is kept stable at around 4℃, reducing the physiological activity of the fish meat and ensuring the stability of inoculation.

[0067] 4. Surface inoculation: Use the surface inoculation method. Dip a sterile cotton swab in the prepared bacterial solution and evenly spread it on the surface of the fish pieces, ensuring that the fish meat is fully covered by the bacterial solution. The inoculation amount should be 5% (v / w) of the fish piece weight, that is, 2.5 mL of bacterial solution per 50g fish piece. After inoculation, seal the sample bag and place it in an anaerobic fermenter for constant temperature anaerobic fermentation at 37℃ for 3 hours.

[0068] Comparative blank control group test

[0069] Tilapia and bonito fillets of the same size were selected and subjected to the same pretreatment, disinfection, and precooling processes. No Lactobacillus pentosus culture was inoculated. The fillets were coated with sterile saline in the same proportion. The fermentation environment and fermentation cycle were completely consistent with the experimental group, serving as a blank control group.

[0070] Test Case Deodorization Effect Detection and Analysis

[0071] 1. Determination of total lactic acid bacteria count before and after fermentation

[0072] The total number of lactic acid bacteria in fish samples before and after fermentation was determined by the plate coating count method, with three parallel experiments set up for each group.

[0073] The counting results showed that at the initial stage of fermentation inoculation, the total number of lactic acid bacteria in the tilapia flesh was 7.25 × 10⁻⁶. 8 The total CFU / g of the skipjack tuna meat was 8.45 × 10⁻⁶ CFU / g. 8 CFU / g; After short-term anaerobic fermentation at 37℃ for 3 h, the strain proliferated rapidly, and the total number of lactic acid bacteria in the tilapia reached 1.43 × 10⁻⁶ at the end of fermentation. 9 CFU / g, the total lactic acid bacteria count of the skipjack tuna reached 1.52×10 9 CFU / g.

[0074] The results showed that Lactobacillus pentosus HY-1010 exhibited high growth activity and strong colonization ability at 37℃, and could proliferate rapidly through short-term fermentation, thus quickly exerting its deodorizing effect.

[0075] 2. Sensory evaluation test

[0076] A 10-person sensory evaluation team was formed to conduct sensory evaluations on four groups of samples: tilapia with fishy smell intact, tilapia with fishy smell removed, skipjack tuna with fishy smell intact, and skipjack tuna with fishy smell removed. The evaluation dimensions included odor (30 points), color (20 points), fishy smell intensity (30 points), and elasticity (20 points), with a total score of 100 points. A higher fishy smell score indicated a weaker fishy smell, and a higher elasticity score indicated better meat elasticity. Figure 5 A statistical chart showing the sensory evaluation scores for fish meat.

[0077] The results showed that the total scores of the unremoved tilapia and the unremoved skipjack tuna were 62.0 and 50.0 respectively, with fishy smell scores of only 12.5 and 9.5, indicating a noticeable and unpleasant fishy odor. After being fermented with Lactobacillus pentosus HY-1010 to remove the fishy smell, the total scores of the deodorized tilapia and deodorized skipjack tuna increased to 84.5 and 74.5 respectively, with fishy smell scores significantly improved to 23.5 and 21.5, respectively. The fishy smell was fresh and without any irritating odor, and the color was bright and uniform.

[0078] In terms of meat elasticity, tilapia is significantly more elastic than skipjack tuna, consistent with the natural characteristics of both fish: tilapia with unremoved odor scored 15.5 points in elasticity, which increased to 18.5 points after odor removal; skipjack tuna with unremoved odor scored 10.5 points in elasticity, which increased to 13.5 points after odor removal. Odor removal treatment effectively improves the elasticity and chewiness of fish meat while preserving the inherent textural characteristics of the fish species, while also achieving a significant effect of removing odor and enhancing aroma.

[0079] 3. GC-MS Detection and Thermal Analysis of Volatile Flavor Compounds

[0080] Gas chromatography-mass spectrometry (GC-MS) was used to qualitatively and quantitatively analyze the volatile flavor compounds of tilapia (LB: non-deodorized group, LW: deodorized group) and skipjack tuna (JB: non-deodorized group, JW: deodorized group) before and after fermentation. Compounds with a matching degree >80% were included in the analysis. More than 60 volatile compounds were qualitatively detected and classified into seven categories according to chemical structure: acids, alcohols, esters, aldehydes, ketones, alkanes and heterocyclic compounds. Figure 6 The GC-MS thermograms of volatile substances in fish meat before and after deodorization.

[0081] (1) Changes in the flavor of tilapia after fermentation to remove fishy smell

[0082] The core fishy-smelling substances are significantly degraded, and unpleasant flavors are eliminated:

[0083] In the unremoved tilapia (LB group) (as shown in Table 1), 1-octen-3-ol (OVA=2873.56, mushroom / fishy smell) and nonanal (OVA=355.80, grassy / ranny smell) were the main characteristic fishy odor substances and the core source of the fishy smell of tilapia. At the same time, the content of ester aroma substances such as methyl hexanoate, methyl heptanoate, and methyl octanoate was extremely low or undetectable in the LB group. After deodorization by fermentation with Lactobacillus pentosus HY-1010, 1-octen-3-ol, methyl hexanoate, methyl heptanoate, and methyl octanoate were all undetectable in the LW group (OVA=0), and the OVA value of nonanal was significantly reduced to 110.90. The flavor contribution of the fishy odor substances was greatly reduced, and the fishy smell was effectively eliminated.

[0084] The odor activity values ​​and odor characteristics of volatile flavor components in tilapia and skipjack tuna are shown in Table 1.

[0085] Table 1

[0086]

[0087] Significant enrichment of characteristic aroma compounds of lactic acid bacteria, and optimization of flavor profile:

[0088] In the fermentation group (LW group), acetylmethylethanol (acetoin) (OVA=85.03, creamy / light aroma) and 3-methyl-1-butanol (OVA=421.43, winey / fruity aroma), produced by lactic acid bacteria metabolism, became new characteristic aroma substances with OVA values ​​much greater than 1, giving tilapia a mellow fermented milky and fruity aroma. Meanwhile, although myristic acid (OVA=96.91, rancidity) in the LW group had an OVA value >1, it is a free fatty acid, and its rancidity was effectively masked by the creamy and fruity aromas after conversion by lactic acid bacteria, and its overall content was within an acceptable range. Furthermore, the OVA values ​​of esters and alcohols such as 1-nonanol, ethylhexadecanoate, and ethyl linoleate were significantly increased in the LW group, forming a fermentation flavor profile centered on milky and fruity aromas, resulting in a significant improvement in sensory quality.

[0089] (2) Changes in the flavor of bonito after fermentation to remove fishy smell

[0090] The characteristic substances of the sea odor are significantly reduced, and the pungent odor is eliminated:

[0091] In the unremoved fishy smell of skipjack tuna (JB group), nonanal (OVA=323.86, grassy / rancid smell) and 2-undecylone (OVA=65.70, rancid / greasy fishy smell) were the main fishy smell substances, with OVA values ​​>1, and were the main sources of the pungent fishy smell of skipjack tuna; phenylacetaldehyde (OVA=11.54, pungent / greasy smell) also contributed to the unpleasant flavor of skipjack tuna. After fermentation to remove the fishy smell, nonanal and phenylacetaldehyde were not detected in the JW group (OVA=0), and the OVA value of 2-undecylone only increased slightly, with its rancid smell effectively masked by the newly added aroma substances; at the same time, esters such as methyl hexanoate, methyl heptanoate, and methyl octanoate, which were present in the JB group, were not detected in the JW group, indicating that some esters were further metabolized and transformed by lactic acid bacteria during the fermentation process, generating milder flavor substances.

[0092] Esters and alcohols are significantly enriched, forming a unique fermented flavor:

[0093] In the fermentation group (JW group), acetylmethylethanol (acetoin) (OVA=111.48, creamy / fresh aroma) was the core aroma compound, with an OVA value significantly higher than that of the tilapia LW group, giving the skipjack tuna a rich creamy aroma. Meanwhile, although myristic acid (OVA=169.54, rancidity) had a high OVA value, the JW group showed significantly higher OVA values ​​for aroma compounds such as ethyl hexadecanoate (OVA=1.44, fruity / ester aroma) and 1-nonanol (OVA=1.24, floral aroma). These compounds worked synergistically with the creamy aroma to effectively neutralize the rancidity of myristic acid, forming the unique "milky + fruity" fermentation flavor profile of skipjack tuna. Furthermore, the JW group showed significantly lower OVA values ​​for naphthalene (OVA=0.04, resinous aroma) and acetophenone (OVA=4.41, astringent / slightly fishy aroma), greatly reducing their contribution to undesirable flavors and resulting in a more harmonious and mellow overall flavor.

[0094] (3) Conclusion of the comparison between the two fish species

[0095] GC-MS results showed that *Lactobacillus pentosus* HY-1010 exhibited highly efficient deodorizing and aroma-enhancing effects on both tilapia and skipjack tuna: after fermentation, fishy-smelling substances such as lipid-oxidized aldehydes, ketones, and long-chain alkanes were significantly degraded; simultaneously, the content of aroma compounds such as acids, alcohols, ketones, and esters produced by lactic acid bacteria metabolism was significantly increased. Tilapia was dominated by acid and ketone aromas, while skipjack tuna, due to its higher fat content, accumulated more esters, forming the unique flavor profiles of different fish species. The data showed good repeatability, and the trends of all substances conformed to the scientific laws of deodorization through lactic acid bacteria fermentation, with no abnormal trends observed.

[0096] 4. GC-IMS flavor fingerprint analysis

[0097] Gas chromatography-ion mobility spectrometry (GC-IMS) was used to non-destructively detect volatile flavor components in tilapia and skipjack tuna before and after 3 h of fermentation with Lactobacillus pentosus HY-1010 for deodorization, constructing flavor fingerprint profiles. Detection conditions: MXT-5 capillary column was used; high-purity nitrogen was used as the carrier gas; gradient elution was employed; headspace injection temperature was 60℃; incubation time was 15 min; injection volume was 500 μL; and drift tube temperature for ion mobility spectrometry was 45℃. Figure 7 GC-IMS flavor fingerprint of fish meat before deodorization; Figure 8 This is the GC-IMS flavor fingerprint of fish meat after deodorization.

[0098] Tilapia control group: LB1-LB3; fermentation group: LW1-LW3; Skipjack tuna control group: JB1-JB3; fermentation group: JW1-JW3. In the spectra, red / bright yellow areas represent high signal intensity (high content), and blue areas represent low signal intensity (low content). Combining LAV analysis software with Gallery Plot comparison, 32 volatile compounds were qualitatively detected in tilapia, and 40 volatile compounds were qualitatively detected in skipjack tuna. Based on chemical structure, these compounds were classified into seven categories: acids, alcohols, aldehydes, ketones, sulfur / nitrogen-containing compounds, esters, and heterocyclic compounds. The flavor changes in both groups of samples conformed to the scientific mechanism of lactic acid bacteria fermentation for deodorization.

[0099] (1) Changes in the flavor of tilapia after fermentation to remove fishy smell

[0100] In the control groups (LB1~LB3), substances such as methanethiol, 1-propanethiol, dimethyl disulfide, triethylamine, heptanal, butyraldehyde, 2-methylpropanal, and 1-hepten exhibited extremely high signal intensities and are the core sources of the fishy odor in tilapia. These substances are products of protein putrefaction (containing sulfur / nitrogen compounds) or lipid oxidation products (aldehydes, alkenes), possessing a strong putrid, ammonia-like, and rancid odor. After fermentation treatment, the signal intensities of these substances in the LW group significantly decreased, and the characteristic peaks of some substances essentially disappeared, demonstrating a significant and noticeable deodorization effect.

[0101] In the fermentation groups (LW1~LW3), the signal intensities of acids, alcohols, and ketones were significantly increased:

[0102] Acids: Acetic acid, propionic acid, and butyric acid are characteristic metabolic products of lactic acid bacteria, providing a refreshing fermented sour taste, lowering the system pH, inhibiting putrefactive bacteria, and masking residual fishy odor. Alcohols: 2-furanethanol, 3-methylbutanol, and 3-methyl-3-buten-1-ol impart grassy, ​​fruity, and mellow wine aromas. Ketones: 2,3-butanedione, 2,3-pentanedione, and 3-hydroxy-2-butanone (acetoin) provide rich creamy and buttery aromas, significantly improving flavor. The spectra of the three parallel samples in the LW group were highly consistent, indicating that the strain's effect on tilapia flavor regulation was stable and reproducible.

[0103] (2) Changes in the flavor of bonito after fermentation to remove fishy smell

[0104] In the control group (JB1~JB3), substances such as methanethiol, diethyl sulfide, heptanal, butyraldehyde, (E)-2-pentenal, pyridine, and pyrazine showed extremely high signal intensities and are the main sources of the fishy odor in skipjack tuna. After fermentation treatment, the signals of these substances were significantly reduced in the JW group, and the deodorization effect was consistent with that of tilapia, verifying that the strain is equally effective for marine fish.

[0105] In the fermentation groups (JW1~JW3), the signals of esters, alcohols, and acids were significantly enhanced, and the types and contents of esters were significantly higher than those of tilapia, forming the unique fermented flavor of skipjack tuna.

[0106] Esters: Ethyl acetate, ethyl butyrate, ethyl lactate, ethyl 2-methylpropionate, etc., provide rich fruity and floral aromas; Alcohols: Ethanol, 1-propanol, 1-butanol, furfuryl alcohol, provide mellow wine and grassy aromas; Acids: Butyric acid, propionic acid, provide refreshing fermented acidity, inhibit spoilage bacteria, and neutralize fishy odors. The spectra of the three parallel samples in group JW are highly consistent, indicating that the strain has a stable and reliable effect on regulating the flavor of skipjack tuna.

[0107] (3) Conclusion of the comparison between the two fish species

[0108] Lactobacillus pentosolicus HY-1010 has a highly effective deodorizing and flavor-enhancing effect on both tilapia and skipjack tuna.

[0109] The deodorization mechanism was broad and consistent: sulfur / nitrogenous fishy substances and lipid oxidized aldehydes in both fish species were significantly degraded;

[0110] Aroma characteristics differ: Tilapia is dominated by acid and ketone aromas, presenting a mellow fermented milky aroma; Skipjack tuna, due to its higher fat content, has a significantly enriched ester substance, resulting in a more intense fruity aroma.

[0111] The process is stable and reliable: the repeatability of parallel samples in each group is good, the material change trend is consistent with the fermentation law of lactic acid bacteria, there are no abnormal substances, and the data meet the requirements.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A strain of Lactobacillus pentosus HY-1010, characterized in that, The Lactobacillus pentosaccharide HY-1010 was deposited at the China Center for Type Culture Collection (CCTCC) on June 1, 2026, with accession number CCTCC NO:M 20261153, and classified as follows: Lactiplantibacillus pentosus .

2. A method for preparing Lactobacillus pentosus according to claim 1, characterized in that, The steps include the following: Fermentation liquid was added to fish meat and allowed to ferment naturally. Lactobacillus pentosus HY-1010 was then isolated and screened.

3. The method for preparing Lactobacillus pentosus according to claim 2, characterized in that, Specifically, the steps include the following: S1. Collect tilapia meat that has been naturally fermented at 37℃ for 30 hours with added fermentation broth. Under aseptic conditions, remove the skin and bones, mince the fish meat using a meat grinder, accurately weigh the fish paste, and perform serial dilution with sterile physiological saline at a dilution gradient of 10. -5 ~10 -7 ; S2. Different gradient dilutions were spread onto MRS solid medium and anaerobic cultured. Single colonies with clear calcium dissolution zones and regular colony morphology were picked and purified three times using the three-zone streak method to obtain Lactobacillus pentosus HY-1010.

4. The method for preparing Lactobacillus pentosus according to claim 3, characterized in that, In step S2, the anaerobic culture temperature is 30℃ and the anaerobic culture time is 24~48 h.

5. The method for preparing Lactobacillus pentosus according to claim 2, characterized in that, The fish meat is either tilapia meat or bonito meat.

6. The method for preparing Lactobacillus pentosus according to claim 2, characterized in that, The fermentation broth comprises the following components by mass percentage: 2 wt% sodium chloride, 2 wt% glucose, and the balance being sterile water.

7. The use of Lactobacillus pentosus HY-1010 as described in claim 1 in the preparation of a microbial deodorizing agent.

8. A microbial deodorizing agent, characterized in that, The microbial deodorizing agent contains *Lactobacillus pentosus* as described in claim 1, and the viable count is not less than 1 × 10⁻⁶. 9 CFU / mL.

9. The application of the microbial deodorizing agent according to claim 8 in the fermentation and deodorization of food-grade aquatic products.

Images