Method for removing fishy smell and enhancing fragrance of kelp

Abstract

The invention discloses a method for removing fishy smell and enhancing aroma of kelp, and belongs to the technical field of microbial fermentation. According to the method, the kelp is subjected to compound fermentation by using the high-activity yeast, the lactobacillus plantarum 120 and the Wickerhamomyces anomalus YZ22, the fishy smell removal efficiency is high, the reaction is mild, chemical fishy smell removal components do not need to be added, and the method is a green fishy smell removal method. By adopting the microbial compound fermentation fishy smell removal method disclosed by the invention, fishy smell substances can be better removed, some fragrant substances can be generated, and the microbial compound fermentation fishy smell removal method has the effects of removing fishy smell and enhancing fragrance, and has better application value and practical significance.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial fermentation, and particularly relates to a method for removing fishy smell and enhancing fragrance of kelp. Background Art

[0002] According to the "China Fisheries Statistical Yearbook", the output of algae in 2022 was 2.7239 million tons, of which kelp output was 1.4305 million tons, making it the most abundant type of algae. Kelp is rich in nutrients and contains nutrients such as protein, amino acids, vitamins, manganese, zinc, copper, and selenium. The rich vitamins, carotene, niacin, alginate, amino acids, mannitol, unsaturated fatty acids, alginic acid and other substances in kelp are its main functional substances, which are beneficial for preventing thrombosis, cancer, diabetes, cholesterol, etc. Among them, the rich brown algae polysaccharide can regulate immunity, anti-oxidation, anti-virus, anti-inflammatory and bactericidal. Therefore, kelp is known as the "longevity vegetable" and is widely consumed.

[0003] However, due to the fishy smell on the surface of kelp, kelp processing is mainly based on primary processing, which is single in form and low in added value, so that kelp resources are not fully utilized. At present, there are mainly physical, chemical and microbial methods for the deodorization of kelp. Physical deodorization generally involves simple covering and embedding of fishy substances, which does not change the molecular composition of fishy substances or cause them to change, and therefore cannot fundamentally remove the fishy components. The chemical deodorization process will cause the loss of some nutrients and is accompanied by certain dangers. Moreover, the residual waste residues of chemical reagents will also cause environmental hazards. The microbial deodorization method mainly achieves the deodorization effect by inoculating microorganisms in kelp samples. Compared with the chemical deodorization method, the microbial deodorization method does not require the addition of other substances. It is a green deodorization method and has the advantages of high deodorization efficiency and mild reaction. Therefore, exploring a microbial deodorization method with excellent deodorization effect is of practical significance for the processing and application of kelp products. Summary of the invention

[0004] The present invention provides a method for removing fishy smell and enhancing fragrance of kelp, the steps of which are as follows:

[0005] The kelp homogenate is inoculated with a suspension of plant lactobacillus 120, fermented, and sterilized after the fermentation is completed; then, the kelp fermented with plant lactobacillus 120 is inoculated with a suspension of abnormal Wickham yeast YZ22, fermented, and sterilized after the fermentation is completed; finally, the kelp fermented with abnormal Wickham yeast YZ22 is inoculated with highly active yeast, fermented, and sterilized after the fermentation is completed to obtain the deodorized and flavored kelp.

[0006] In the above method, the inoculation amount of the Lactobacillus plantarum 120 suspension is selected from 0.7-1.0%, preferably 0.8%; the inoculation amount of the abnormal Wickham yeast YZ22 suspension is selected from 0.9-1.2%, preferably 1%; the inoculation amount of the high-activity yeast is selected from 0.2-0.5%, preferably 0.3%.

[0007] In the above method, the fermentation conditions of the Lactobacillus plantarum 120 are selected from: fermentation at 35-38°C and 140-180r / min for 2-5h; preferably: fermentation at 37°C and 150r / min for 3h.

[0008] In the above method, the fermentation conditions of the abnormal Wickham yeast YZ22 are selected from: fermentation at 28-32°C and 140-180r / min for 0.8-1.2h; preferably: fermentation at 30°C and 150r / min for 1h.

[0009] In the above method, the fermentation conditions of the highly active yeast are selected from: fermentation at 28-32°C and 140-180r / min for 0.4-0.7h; preferably: fermentation at 30°C and 150r / min for 30min.

[0010] In the above method, the sterilization method is ultraviolet sterilization.

[0011] In the above method, the Lactobacillus plantarum 120 suspension is prepared by the following method:

[0012] Lactobacillus plantarum 120 was inoculated into MRS liquid culture medium and cultured at 30°C for 24 h. After activation twice, the culture solution was frozen and centrifuged, and then the obtained bacteria were washed with physiological saline, centrifuged, and finally suspended in physiological saline to control the viable cell count of Lactobacillus plantarum 120 to 1×10 9 cfu / mL, and obtain Lactobacillus plantarum 120 suspension.

[0013] In the above method, the abnormal Wickham yeast YZ22 suspension is prepared by the following method:

[0014] The abnormal Wickham yeast YZ22 was inoculated into YPD liquid medium and cultured at 30°C for 24 h. After activation twice, the culture solution was frozen and centrifuged, and then the obtained bacteria were washed with physiological saline, centrifuged, and finally suspended in physiological saline. The viable cell count of abnormal Wickham yeast YZ22 was controlled at 1×10 7 cfu / mL, and obtain the suspension of abnormal Wickham yeast YZ22.

[0015] In the above method, the kelp homogenate is prepared by the following method:

[0016] Soak the dried kelp at room temperature for 4 hours. After soaking, wash it with clean water 5 times to remove mud and mucus on the surface of the kelp. Cut the kelp into appropriate sizes, then add water at a material-liquid ratio of 1:3, and use a pulper to make a kelp homogenate.

[0017] The invention provides deodorized and flavored kelp prepared by the method.

[0018] The beneficial effects of the present invention are:

[0019] The present invention utilizes highly active yeast, plant lactobacillus 120 and abnormal Wickham yeast YZ22 to compound ferment kelp, which has high deodorization efficiency and mild reaction, and does not require the addition of chemical deodorization components, and is a green deodorization method. By adopting the microbial compound fermentation deodorization method of the present invention, fishy substances can be better removed, and some aromatic substances can be produced, which has the effect of removing fishy smell and enhancing fragrance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The fishy smell sensory score of kelp fermented with high-activity yeast under different inoculation conditions;

[0021] Figure 2 The fishy smell sensory score of kelp fermented by high-activity yeast under different fermentation temperature conditions;

[0022] Figure 3 The fishy smell sensory score of kelp fermented with high-activity yeast at different fermentation time conditions;

[0023] Figure 4 The fishy smell sensory scores of kelp fermented with Lactobacillus plantarum 120 under different inoculation conditions;

[0024] Figure 5 The fishy smell sensory score of kelp fermented by Lactobacillus plantarum 120 under different fermentation temperature conditions;

[0025] Figure 6 The fishy smell sensory score of kelp fermented by Lactobacillus plantarum 120 at different fermentation time conditions;

[0026] Figure 7 The fishy smell sensory scores of kelp fermented by abnormal Wickham yeast YZ22 under different inoculation conditions;

[0027] Figure 8 The fishy smell sensory scores of kelp fermented by abnormal Wickham yeast YZ22 under different fermentation temperature conditions;

[0028] Fig. 9 The fishy smell sensory scores of kelp fermented by abnormal Wickham yeast YZ22 under different fermentation time conditions;

[0029] Fig.10To evaluate the fishy smell of compound fermented kelp;

[0030] Fig.11 These are the results of electronic nose analysis of kelp fermented by various strains. DETAILED DESCRIPTION

[0031] In the present invention, Lactobacillus plantarum 120 is a known strain (Jinhong Z, Yanshun X, Wenshui X, et al. Dynamics and diversity of microbial community succession during fermentation of Suan yu, a Chinese traditional fermented fish, determined by high throughput sequencing [J]. Food Research International, 2018, 111: 565-573.), which is preserved by the 2021 Laboratory of the Specialty Food Research Institute of Qingdao Agricultural University. The applicant also guarantees that the public can obtain the biological material from this laboratory within 20 years from the date of application. Highly active yeast was purchased from AB Mali (Beijing) Food Sales Co., Ltd., Yanshan brand highly active dry yeast (low sugar type, net content 10g). Wickerhamomyces anomalus YZ22 was deposited in the General Microbiology Center of China Microorganism Culture Collection (CGMCC for short, address: No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, Postal Code 100101) on October 27, 2023, with the deposit number CGMCC No. 28806.

[0032] MRS liquid medium:

[0033] Peptone 10.0g / L, beef extract powder 8.0g / L, yeast extract powder 4.0g / L, glucose 20.0g / L, dipotassium hydrogen phosphate 2.0g / L, diammonium hydrogen citrate 2.0g / L, sodium acetate 5.0g / L, magnesium sulfate 0.2g / L, manganese sulfate 0.04g / L, Tween 80

[0034] 1.0g / L.

[0035] YPD liquid medium:

[0036] Peptone 20.0g / L, glucose 20.0g / L, yeast extract powder 10.0g / L.

[0037] Bacteria activation:

[0038] Lactobacillus plantarum 120: Lactobacillus plantarum 120 (Lp-120) was inoculated into MRS liquid culture medium and cultured at 30°C for 24 hours. After activation twice, the culture solution was centrifuged at 10,000 r / min for 15 minutes. The resulting bacteria were then washed with saline, centrifuged, and finally suspended in saline. The number of viable Lactobacillus plantarum 120 was controlled at 1×10 9 cfu / mL, and obtain Lactobacillus plantarum 120 suspension.

[0039] Abnormal Wickham yeast YZ22: Abnormal Wickham yeast YZ22 was inoculated into YPD liquid culture medium and cultured at 30°C for 24 hours. After activation twice, the culture solution was centrifuged at 10,000 r / min for 15 minutes, and then the obtained bacteria were washed with physiological saline, centrifuged, and finally suspended in physiological saline. The viable count of abnormal Wickham yeast YZ22 was controlled at 1×10 7 cfu / mL, and obtain the suspension of abnormal Wickham yeast YZ22.

[0040] Kelp sample pretreatment:

[0041] Soak the dried kelp at room temperature for 4 hours. After soaking, wash it with clean water 5 times to remove the mud and mucus on the surface of the kelp. Cut the kelp into appropriate sizes, and then add water (solid-liquid ratio 1:3). Use a pulper to make kelp homogenate and put it in a 4℃ refrigerator for use. It should be used up within 2 days.

[0042] The volatile compounds (VOCs) in kelp raw materials are shown in Table 1:

[0043] Table 1 Volatile compounds in kelp raw materials

[0044]

[0045]

[0046] The OAV values ​​of kelp samples are shown in Table 2:

[0047] Table 2 OAV values ​​of kelp samples

[0048] serial number Compound Threshold (μg / kg) OAV 1 trans-2,4-decadienal 0.07 2347.27 2 2-Nonanone 0.05 1883.85 3 trans-2-nonenal 0.4 1685.08 4 1-Octen-3-ol 1.5 871.60 5 trans-ionone 0.6 764.46 6 trans-2-decenal 0.3 484.12 7 Nonanal 1 280.33 8 trans,cis-2,6-nonadienal 0.5 167.71 9 2-n-Pentylfuran 6 144.48 10 Octanal 1 76.84 11 trans-2-octenal 3 62.86 12 Hexanal 5 62.24 13 3-Octanone 40 38.11 14 Heptanal 3 26.63 15 Isobutyraldehyde 1.5 16.35 16 1-Nonanol 90 12.76 17 1-Octanol 80 7.63 18 Heptanol 94 4.20 19 trans-2-octen-1-ol 100 3.81 20 Acetaldehyde 15 3.46 21 Methyl Heptenone 68 1.82 22 n-Hexanol 860 0.95 23 2,2,6-Trimethylcyclohexanone 100 0.45 24 Isoamyl alcohol 500 0.17 25 2-Ethylhexanol 1280 0.10 26 Ethanol 30000 0.08 27 Dihydro-β-ionone 1100 0.07 28 2-Ethylfuran 8000 0.02

[0049] The fishy substances in kelp are shown in Table 3:

[0050] Table 3 Odor substances in kelp

[0051]

[0052]

[0053] In the above Table 3, 30° kelp, 60° kelp and 100° kelp were prepared by heating the above kelp homogenate in a water bath at 30°C, 60°C and 100°C for 30 minutes respectively.

[0054] Other materials used in the present invention, if not otherwise stated, can be obtained through commercial channels. Other terms used in the present invention, unless otherwise specified, generally have the meanings commonly understood by those of ordinary skill in the art. The present invention is further described in detail below in conjunction with specific examples and with reference to data. The following examples are only for illustrating the present invention, and are not intended to limit the scope of the present invention in any way.

[0055] Example 1

[0056] Highly active yeast fermentation to remove fishy smell:

[0057] Highly active yeast was added to 120 mL of kelp homogenate, and then fermented in a constant temperature oscillator. The optimal fermentation conditions were determined through a single factor experiment.

[0058] The single-factor experimental conditions were set as follows:

[0059] (1) While maintaining the fermentation temperature at 30°C and the inoculum size at 0.3%, the fermentation time was changed to 10 min, 20 min, 30 min, and 40 min, respectively;

[0060] (2) While keeping the fermentation time at 30 min and the inoculum size at 0.3%, the fermentation temperature was changed to 26°C, 28°C, 30°C, and 32°C respectively;

[0061] (3) While keeping the fermentation time at 30 min and the fermentation temperature at 30°C unchanged, the inoculation amount of the bacterial strain was changed to 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% of the mass of the kelp for fermentation and deodorization.

[0062] Example 2

[0063] Lactobacillus plantarum 120 fermentation to remove fishy smell:

[0064] Lactobacillus plantarum 120 was added to 120 mL of kelp homogenate, and then fermented in a constant temperature oscillator. The optimal fermentation conditions were determined through a single factor experiment.

[0065] The single-factor experimental conditions were set as follows:

[0066] (1) While maintaining the fermentation temperature at 37°C and the inoculum size at 0.8%, the fermentation time was changed to 1 h, 2 h, 3 h, 4 h, and 5 h respectively;

[0067] (2) While keeping the fermentation time at 3 h and the inoculum size at 0.8%, the fermentation temperature was changed to 28°C, 32°C, 37°C, and 42°C, respectively;

[0068] (3) While keeping the fermentation time at 3 h and the fermentation temperature at 37°C unchanged, the inoculation amount of the bacterial strain was changed to 0.6%, 0.7%, 0.8%, 0.9%, and 1.0% of the mass of the kelp for fermentation and deodorization.

[0069] Example 3

[0070] Abnormal Wickham yeast YZ22 fermentation to remove fishy smell:

[0071] The abnormal Wickham yeast YZ22 was added to 120 mL of kelp homogenate, and then fermented in a constant temperature oscillator. The optimal fermentation conditions were determined by single factor experiments.

[0072] The single-factor experimental conditions were set as follows:

[0073] (1) While maintaining the fermentation temperature at 30°C and the inoculum size at 1%, the fermentation time was changed to 20 min, 40 min, 60 min, 80 min, and 120 min, respectively;

[0074] (2) While keeping the fermentation time at 60 min and the inoculum size at 1%, the fermentation temperature was changed to 26°C, 28°C, 30°C, and 32°C respectively;

[0075] (3) While keeping the fermentation time at 60 min and the fermentation temperature at 30°C unchanged, the inoculation amount of the bacterial strain was changed to 0.6%, 0.8%, 1.0%, 1.2%, and 1.4% of the mass of the kelp for fermentation and deodorization.

[0076] 1. Analysis of fermentation deodorization index

[0077] 1. Electronic nose analysis

[0078] 5 mL of kelp fermentation liquid was drawn into a 20 mL headspace gas sample bottle, and three samples were set in parallel. 5 mL of kelp homogenate was taken into a headspace injection bottle and placed in a 30°C constant temperature water bath for 30 min. Electronic nose conditions: cleaning time 100 s, test time 15 s, detection time 120 s, gas flow rate 0.3 L / min.

[0079] 2. GC-MS detection

[0080] The solid phase microextraction method was used to extract the volatile flavor substances of the samples before and after fermentation. 2g of kelp homogenate was placed in a 20mL headspace bottle, 100ppm of internal standard 2,4,6-trimethylpyridine was added and mixed evenly, the aged extraction head was inserted into the headspace of the sample bottle, adsorbed at 60℃ for 30min, the adsorbed extraction head was taken out and inserted into the gas chromatography injection port, and desorbed at 250℃ for 3min.

[0081] GC-MS analysis GC conditions are as follows: flexible capillary column DB-WAX, 30m×0.25mm×0.25μm; column initial temperature 40℃, maintained for 3min, then heated to 90℃ at a rate of 5℃ / min, then heated to 230℃ at a rate of 10℃ / min, maintained for 7min, interface temperature 250℃. MS conditions are as follows: ion source uses EI + , emission current 80μA, ionization voltage 70eV, scanning range 30-500m / z, interface temperature 250℃, ion source temperature 200℃, carrier gas helium, constant flow rate of 0.9mL / min, detector voltage 1000V. Automatic retrieval was performed using NIST2005 and Willey7 standard libraries, and the retention index (RI) of volatile compounds was calculated by the retention time of C8-C26 normal alkanes. The concentration of volatile compounds in the sample was calculated by comparing the peak area of ​​each compound with the peak area of ​​the internal standard, expressed as μg / kg.

[0082] 3. Calculation of Odor Activity Value (OAV)

[0083] The odor activity value (OAV) is a ratio of the flavor substance content quantified by instruments such as GC-MS to its olfactory threshold (the lowest concentration that a person can smell) to assess the contribution of the flavor substance to the overall flavor.

[0084] The calculation method is: OAV=c / OT.

[0085] Where c is the concentration of a certain VOC (μg / kg), and OT represents the odor threshold reported in the literature (μg / kg). Compounds with OAVs above 1 are considered to have a significant contribution to aroma composition. For compounds with multiple thresholds, the most recent data was selected.

[0086] 4. Sensory evaluation

[0087] Ten professionally trained personnel were selected to conduct sensory evaluation of the fishy smell of kelp paste before and after deodorization. Scores were made based on the single factor changes of fermentation time, temperature and bacterial inoculation amount each time. The score was 1-5, where 0 means no fishy smell; 1 means basically no fishy smell; 2 means weak fishy smell; 3 means fishy smell; 4 means average fishy smell; 5 means strong fishy smell. The total fishy smell score of each sample was calculated.

[0088] 2. Evaluation of fermentation deodorization effect

[0089] 1. Highly active yeast fermented kelp

[0090] like Figure 3 As shown in the figure, when the fermentation time is between 10 and 30 minutes, the deodorization effect becomes more and more ideal as the fermentation time increases. When the fermentation time is 30 minutes, the sensory quality after deodorization is the best. As the time goes by, the sensory score decreases. This is mainly because the increase in fermentation time increases the odor produced by bacterial fermentation, and the kelp paste loses its original kelp flavor, affecting the sensory quality. Figure 2 As shown in the figure, when the fermentation temperature is 30℃, the sensory quality after deodorization is the best. Too low a temperature will limit the activity of the bacteria and slow down the fermentation process. As the temperature rises, the bacteria will over-ferment and produce odor, affecting the taste and mouthfeel. Therefore, 30℃ was selected for subsequent experiments. Figure 1 As shown, with the increase of inoculation amount, the deodorization effect continues to improve. Through microbial metabolism, some fishy substances in kelp can be removed, which increases the sensory score. When the inoculation amount exceeds 0.3%, excessive bacterial reproduction increases metabolic waste, resulting in a decrease in the sensory quality of kelp paste.

[0091] Under the optimal deodorization conditions of high-activity yeast, i.e., inoculation amount of 0.3%, fermentation temperature of 30°C, and fermentation time of 30 min, the kelp homogenate was fermented. The kelp fishy substances after fermentation were detected and analyzed by GC-MS, as shown in Table 4:

[0092] Table 4 Odor substances of kelp fermented by high-activity yeast

[0093]

[0094]

[0095] Through high-activity yeast fermentation, the fishy substances in kelp, such as trans-2,4-decadienal, trans-2-decenal, trans-cis-2,6-nonadienal, trans-2-octenal, (Z)-4-heptenal, 1-octen-3-one, 2-undecenal, sec-octanone, trans-2-nonen-1-ol, and geranyl acetone, are removed. The content of fishy substances such as trans-2-nonenal, 1-octen-3-ol, 2-n-pentylfuran, hexanal, methyl heptenone, and 2-heptanone is reduced. The newly generated isovaleraldehyde has chocolate flavor and peach flavor, phenylacetaldehyde has a sweet fruity aroma, phenylethanol has a sweet rose-like floral aroma, and 2-ethylhexanol has a floral smell. The content in the deodorized kelp is higher than that of the original. The newly generated 2-heptanone in the deodorized kelp has a strong fruity aroma, which plays an important role in the formation of the special aroma of kelp paste. By fermenting kelp with highly active yeast, the fishy odor substances are removed or their content is reduced, and new aromatic substances are produced, making the kelp flavor better.

[0096] 2. Lactobacillus plantarum 120 fermented kelp

[0097] like Figure 6 As shown in the figure, with the increase of fermentation time, the sensory quality of kelp paste becomes better and better. When the fermentation time exceeds 3h, the taste and mouthfeel of kelp paste become astringent, the sensory quality is affected, and the sensory score begins to decrease. Figure 5 As shown in the figure, when the fermentation temperature exceeds 37°C, a large number of bacteria begin to die, causing the odor of kelp paste to change and the sensory score to decrease; as the inoculation amount of Lactobacillus plantarum increases, the aromatic compounds produced by fermentation increase, which can cover up the fishy smell of kelp and produce a pleasant special aroma. Figure 4 As shown, when the inoculation amount exceeds the critical value of 0.8%, the taste produced by the fermentation begins to be strong and causes discomfort, so 0.8% is selected as the optimal inoculation amount.

[0098] Under the optimal deodorization conditions of Lactobacillus plantarum 120, i.e., the inoculation amount was 0.8%, the fermentation temperature was 37°C, and the fermentation time was 3h, the kelp homogenate was fermented, and the kelp fishy smell substances after fermentation were detected and analyzed by GC-MS, as shown in Table 5:

[0099] Table 5 Odor substances of kelp fermented by Lactobacillus plantarum 120

[0100]

[0101]

[0102] The fishy substances in kelp, trans-2-decenal, trans-cis-2,6-nonadienal, 2-pentylfuran, methyl heptenone, (Z)-4-heptenal, and 2-undecenal were removed, and the contents of the fishy substances in kelp, trans-2,4-decadienal, trans-2-nonenal, 1-octen-3-ol, trans-2-octenal, hexanal, 1-octen-3-one, sec-octanone, trans-2-nonen-1-ol, 2-heptanone, and geranyl acetone were reduced. Most of the fishy substances were removed by fermentation with Lactobacillus plantarum, and the OAV of the remaining fishy substances were reduced.

[0103] 3. Abnormal Wickham yeast YZ22 fermented kelp

[0104] like Fig. 9 As shown in the figure, as the fermentation time increases, the smell of kelp paste improves. When the fermentation exceeds 60 minutes, the sensory quality of kelp paste also decreases. Figure 7 and Figure 8 As shown in the figure, with the increase of fermentation temperature and inoculation amount, the fermentation enters the optimal stage. When the temperature exceeds 30℃ and the inoculation amount exceeds 1%, its smell and taste begin to change, the color of kelp paste begins to turn slightly yellow, and the sensory quality decreases. In summary, the fermentation time of 60min, the fermentation temperature of 30℃ and the inoculation amount of 1% are selected as the best deodorization conditions.

[0105] Under the optimal deodorization conditions of abnormal Wickham yeast YZ22, the kelp homogenate was fermented, and the odor substances of the fermented kelp were detected and analyzed by GC-MS, as shown in Table 6:

[0106] Table 6 Odor substances of kelp fermented by abnormal Wickham yeast YZ22

[0107]

[0108] After adding abnormal Wickham yeast to the kelp homogenate, the fishy substances trans-2-decenal, trans, cis-2,6-nonadienal, (Z)-4-heptenal, 2-undecenal, and trans-2-nonen-1-ol were removed. The content of fishy substances such as trans-2,4-decadienal, trans-2-nonenal, 1-octen-3-ol, 2-n-pentylfuran, trans-2-octenal, hexanal, methyl heptenone, 1-octen-3-one, sec-octanone, 2-heptanone, and geranyl acetone was reduced. The newly generated 2-heptanone in the deodorized kelp fermented with abnormal Wickham yeast has a strong fruity aroma, 2-tridecanone has a coconut aroma, and 3-undecanone has a fruity and vanilla smell, which plays an important role in the formation of the special aroma of kelp paste. Abnormal Wickham yeast fermentation of kelp removes some fishy substances, and the content of some fishy substances is reduced. Newly generated substances such as 2-heptanone and 3-methyl-2-butanone play an important role in the formation of the special flavor of kelp. Abnormal Wickham yeast has a good effect on removing fishy smell.

[0109] Example 4

[0110] Compound fermentation to remove fishy smell:

[0111] 120 mL of kelp homogenate was inoculated with a suspension of Lactobacillus plantarum 120 at a rate of 0.8%, and fermented at 37° C. and 150 r / min for 3 hours. After the fermentation was completed, the suspension was sterilized by ultraviolet for 30 minutes. Then, the kelp fermented by Lactobacillus plantarum 120 was inoculated with a suspension of abnormal Wickham yeast YZ22 at a rate of 1%, and fermented at 30° C. and 150 r / min for 1 hour. After the fermentation was completed, the suspension was sterilized by ultraviolet for 30 minutes. Finally, the kelp fermented by abnormal Wickham yeast YZ22 was inoculated with highly active yeast at a rate of 0.3%, and fermented at 30° C. and 150 r / min for 30 minutes. After the fermentation was completed, the suspension was sterilized by ultraviolet for 30 minutes to obtain deodorized kelp.

[0112] The above method was used to detect and analyze the deodorization indexes of composite fermentation.

[0113] (1) Analysis of deodorization index

[0114] The results of the analysis of the fishy smell substances of the composite fermented kelp are shown in Table 7:

[0115] Table 7 Odor substances of composite fermented kelp

[0116]

[0117] The results of GC-MS analysis of composite fermented kelp are shown in Table 8:

[0118] Table 8 GC-MS of composite fermented kelp

[0119]

[0120]

[0121] The OAV value analysis results of the composite fermented kelp are shown in Table 9:

[0122] Table 9 OAV value of composite fermented kelp

[0123]

[0124]

[0125] The fishy smell sensory score of compound fermented kelp, such as Fig.10As shown in the figure, through sensory evaluation, the fishy smell of the kelp sample after composite deodorization is better than that of each strain alone, and the GC-MS results show that the composite deodorization greatly removes the fishy substances in the kelp and produces a pleasant flavor. A total of 40 volatile compounds were detected by GC-MS, of which 12 fishy substances such as trans-2,4-decadienal, trans-2-decenal, trans, cis-2,6-nonadienal, 2-n-pentylfuran, trans-2-octenal, methyl heptenone, (Z)-4-heptenal, 1-octen-3-one, 2-undecenal, sec-octanone, trans-2-nonen-1-ol, and geranyl acetone were removed, and the contents of four fishy substances such as trans-2-nonenal, 1-octen-3-ol, hexanal, and 2-heptanone were greatly reduced. After composite fermentation of strains, some new pleasant flavors were generated. Isovaleraldehyde has chocolate flavor and peach flavor, phenylacetaldehyde has sweet fruity aroma, phenylethanol has sweet rose-like floral aroma, the 2-heptanone formed after compound fermentation and deodorization is more abundant than that produced by single strain fermentation, 2-heptanone has a strong fruity aroma, 2-tridecanone has a coconut aroma, 3-undecanone has the smell of fruit and vanilla, the content of newly generated phenylethanol after deodorization is more than that produced by single strain fermentation, phenylethanol has the aroma of roses, and 3-methyl-2-butanone has an aromatic smell. These volatile compounds newly generated by compound fermentation play an important role in the formation of the special aroma of kelp pulp.

[0126] (2) Electronic nose analysis

[0127] Principal component analysis (PCA) can reduce the dimension of a large amount of complex data into two-dimensional coordinates, and distinguish the differences in volatile gases of different samples through the variance corresponding to the two-dimensional coordinates. A sum greater than 80% can better reflect the actual situation of the sample.

[0128] The electronic nose analysis results of kelp raw materials, kelp fermented with Lactobacillus plantarum 120, kelp fermented with abnormal Wickham yeast YZ22, kelp fermented with high-activity yeast and composite fermented kelp are as follows Fig.11 shown.

[0129] The overall contribution rate of the two principal components (PC1 and PC2) reached 94.3%, indicating that the PCA analysis method can accurately distinguish the differences between samples. From the perspective of the first principal component PC1 axis, the classification of each group of samples is obvious, and the distance between the composite bacterial fermentation kelp sample value and the kelp original sample is far, indicating that the degree of change in its odor is large. In the dimensionality reduction analysis, the first principal component PC1 with a larger variance contribution rate is mainly considered. By comparing the average distance between the center of each group of sample data points and the blank control data point, it can be seen that composite bacterial fermentation can most effectively change the sample odor and has the most significant effect on the deodorization effect of kelp.

[0130] (3) Comprehensive sensory evaluation

[0131] The color, smell, flavor, taste and mouthfeel of kelp paste fermented by Lactobacillus plantarum 120, kelp paste fermented by high-activity yeast, kelp paste fermented by abnormal Wickham yeast YZ22 and kelp paste fermented by bacterial species were evaluated by sensory evaluation. The higher the score, the better. The scoring criteria are shown in Table 10:

[0132] Table 10 Comprehensive sensory evaluation standards

[0133]

[0134] The comprehensive sensory evaluation results are shown in Table 11:

[0135] Table 11 Comprehensive sensory evaluation of kelp paste after deodorization by various strains of kelp

[0136]

[0137] After being deodorized by highly active yeast, the kelp paste turned light green, with a slight fishy smell but within an acceptable range, and there was no significant change in flavor and taste. After being deodorized by Lactobacillus plantarum 120, the kelp paste turned slightly yellowish green in color. Although the fishy smell was removed, it was worse than the other three groups, and the sensory quality after deodorization was slightly worse than the other three groups. The fishy smell of kelp fermented by abnormal Wickham yeast YZ22 was improved, and the color was light green, but the fishy smell and flavor were worse than those fermented by composite bacteria. After being deodorized by composite bacteria fermentation, the kelp paste turned normal grass green, the fishy smell was reduced, and the taste and mouthfeel were slightly sweet. The sensory score of kelp paste deodorized by composite bacteria fermentation was the highest among the four groups.

[0138] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for removing fishy smell and enhancing flavor of kelp, characterized in that: Here are the steps: The kelp homogenate is inoculated with a suspension of plant lactobacillus 120, fermented, and sterilized after the fermentation is completed; then, the kelp fermented with plant lactobacillus 120 is inoculated with a suspension of abnormal Wickham yeast YZ22, fermented, and sterilized after the fermentation is completed; finally, the kelp fermented with abnormal Wickham yeast YZ22 is inoculated with highly active yeast, fermented, and sterilized after the fermentation is completed to obtain the deodorized and flavored kelp.

2. The method according to claim 1, characterized in that The inoculation amount of the plant lactobacillus 120 suspension is selected from 0.7 to 1.0%; the inoculation amount of the abnormal Wickham yeast YZ22 suspension is selected from 0.9 to 1.2%; and the inoculation amount of the high-activity yeast is selected from 0.2 to 0.5%.

3. The method according to claim 1, characterized in that The fermentation conditions of the Lactobacillus plantarum 120 are selected from: fermentation at 35-38° C. and 140-180 r / min for 2-5 hours.

4. The method according to claim 1, characterized in that: The fermentation conditions of the abnormal Wickham yeast YZ22 are selected from: fermentation at 28-32° C. and 140-180 r / min for 0.8-1.2 h.

5. The method according to claim 1, characterized in that The fermentation conditions of the highly active yeast are selected from: fermentation at 28-32° C. and 140-180 r / min for 0.4-0.7 h.

6. The method according to claim 1, characterized in that The sterilization method is ultraviolet sterilization.

7. The method according to claim 1, characterized in that The Lactobacillus plantarum 120 suspension is prepared by the following method: Lactobacillus plantarum 120 was inoculated into MRS liquid culture medium and cultured at 30°C for 24 h. After activation twice, the culture solution was frozen and centrifuged, and then the obtained bacteria were washed with physiological saline, centrifuged, and finally suspended in physiological saline to control the viable cell count of Lactobacillus plantarum 120 to 1×10 9 cfu / mL, and obtain Lactobacillus plantarum 120 suspension.

8. The method according to claim 1, characterized in that The abnormal Wickham yeast YZ22 suspension is prepared by the following method: The abnormal Wickham yeast YZ22 was inoculated into YPD liquid medium and cultured at 30°C for 24 h. After activation twice, the culture solution was frozen and centrifuged, and then the obtained bacteria were washed with physiological saline, centrifuged, and finally suspended in physiological saline. The viable cell count of abnormal Wickham yeast YZ22 was controlled at 1×10 7 cfu / mL, and obtain the suspension of abnormal Wickham yeast YZ22.

9. The method according to claim 1, characterized in that: The kelp homogenate is prepared by the following method: Soak the dried kelp at room temperature for 4 hours. After soaking, wash it with clean water 5 times to remove mud and mucus on the surface of the kelp. Cut the kelp into appropriate sizes, then add water at a material-liquid ratio of 1:3, and use a pulper to make a kelp homogenate.

10. Deodorized and flavored kelp prepared by the method according to any one of claims 1 to 9.

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