A method for optimizing the flavor of fermented potato juice based on the inhibition of lipoxygenase activity

Abstract

The present application relates to a kind of fermentation potato juice flavor optimization methods based on lipoxygenase activity inhibition, comprising the following steps: after acid color protection treatment, potato is prepared potato juice, wherein polyphenol, soluble dietary fiber and metal ion are added, and inoculated streptococcus thermophilus and lactis lactis compound strain is fermented, and fermentation potato juice is prepared.The present application establishes multidimensional inhibition lipoxygenase activity regulation system by the synergistic effect of acid color protection treatment, active substance addition, metal ion addition and fermentation treatment, effectively solve the earthy smell problem caused by enzymatic reaction in potato juice.Flavoromics analysis confirms that fermentation treatment is the core factor driving metabolic profile difference, and active substance and metal ion present progressive synergistic regulation effect.Fermentation potato juice prepared by the present application has good flavor, lipoxygenase activity inhibition rate is significantly improved, and has good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and specifically to a method for optimizing the flavor of fermented potato juice based on the inhibition of lipoxygenase activity. Background Technology

[0002] Potato juice, as a plant-based beverage, is rich in various active ingredients such as polysaccharides, alkaloids, proteins, and polyphenols, meeting consumers' demand for healthy drinks. However, potato juice is prone to developing an unpleasant earthy taste during processing and storage, severely limiting its flavor acceptance and market promotion. Research shows that the earthy taste in potato juice mainly originates from 1-octen-3-ol, which is primarily produced by the catalysis of linoleic acid by lipoxygenase (LOX). Lipoxygenase is a redox enzyme widely distributed in animal and plant cells, capable of catalyzing the oxidation of polyunsaturated fatty acids. The volatile aldehyde flavor compounds produced by its catalysis have a significant impact on the flavor of potatoes. During the refrigerated storage of cooked potatoes, the development of the earthy taste is closely related to lipoxygenase activity, representing a serious problem in food processing systems. Therefore, inhibiting lipoxygenase activity is a key approach to improving the flavor of potato juice.

[0003] Currently, the main method for inhibiting lipoxygenase activity relies on heat treatment. However, heat treatment alone has limited effectiveness and may adversely affect the product's nutrition and flavor. Organic acid treatment has also been used to inhibit enzyme activity. Organic acids such as citric acid can inhibit lipoxygenase activity by lowering the pH of the system, causing conformational changes in the enzyme's active site. However, the effect of acidification alone on improving flavor remains limited.

[0004] Existing technologies have reported research on potato fermented beverages. For example, CN111903884A discloses a processing method for a potato enzyme beverage that aids digestion and strengthens the spleen; another patent application discloses a potato compound fermentation juice and its optimization method, which involves pulping and steaming potatoes, adding egg white enzymatic hydrolysate and milk, ultrasonically treating the mixture, and then fermenting it using a compound strain composed of Lactobacillus bulgaricus, Streptococcus lactis, and Lactobacillus acidophilus. However, existing fermented potato beverages generally suffer from problems such as limited nutritional value, poor storage stability, and easy stratification. How to improve the flavor while enhancing the nutritional value and storage stability of the product is a technical problem that needs to be solved in this field.

[0005] Previous studies have demonstrated that polyphenols extracted from plants can interrupt the lipid oxidation chain reaction by chelating or reducing ferrous ions at the active site of LOX, or by reacting with lipid free radicals, thus achieving good oxidative inhibition. However, there are currently no reports on the synergistic application of polyphenols, soluble dietary fiber, and metal ions in the inhibition of lipoxygenase activity and flavor optimization in potato juice.

[0006] Therefore, developing an optimized method that can synergistically inhibit lipoxygenase activity and improve the flavor and quality of potato juice through multiple means is of great significance for improving the quality of potato juice products and meeting consumers' demand for healthy beverages. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide a method for optimizing the flavor of fermented potato juice based on the inhibition of lipoxygenase activity.

[0008] To achieve the aforementioned objective, the technical solution of the present invention is implemented as follows: A method for optimizing the flavor of fermented potato juice based on the inhibition of lipoxygenase activity, comprising the following steps: First, potato juice is prepared by treating potatoes with color protection; polyphenols, soluble dietary fiber, and metal ions are added to the juice; then, a compound bacterial strain is inoculated for fermentation to obtain fermented potato juice. 1) Potato color protection treatment: Wash and cut fresh potatoes into chunks, soak them in a citric acid solution with a concentration of 3% to 8% for 5 to 20 minutes for color protection treatment, then remove and drain for later use.

[0009] 2) Preparation of potato juice base matrix: Mix the potato chunks treated in step 1) with distilled water at a ratio of 1:0.5 to 1:2 (w / v), add 0.5% to 2% polyphenols, 1% to 4% soluble dietary fiber, and 0.5% to 3% metal ions by weight of potato juice; crush the mixture and stir it evenly, filter it through gauze to remove coarse fiber and large particle residue, and obtain potato juice stock solution.

[0010] The polyphenols are preferably extracted from potato peels using a colloid mill-ultrasonic co-processing method; the soluble dietary fiber is preferably extracted from the potato peel precipitate after polyphenol extraction using a high-temperature, high-pressure process. The metal ion is preferably Fe. 3+ It is added in the form of soluble iron salts.

[0011] 3) Pasteurization: Pasteurize the potato juice stock solution obtained in step 2) at 65-85℃ for 10-30 minutes to kill miscellaneous bacteria while maximizing the preservation of heat-sensitive active ingredients.

[0012] 4) Centrifugation and clarification: Centrifuge the sterilized potato juice from step 3) at 3000-5000×g for 10-30 minutes, and take the supernatant as the base fermentation substrate for potato juice.

[0013] 5) Strain activation and compounding: Streptococcus thermophilus and Lactococcus cremoris were activated and cultured separately to prepare strains with a concentration of 1.0 × 10⁻⁶. 7~1.0×10 9 A mixed starter culture was prepared by mixing a seed culture of CFU / mL with Streptococcus thermophilus and Lactococcus lactis in a ratio of 1:1 to 1:5.

[0014] 6) Inoculation and fermentation: Inoculate the mixed fermentation agent into the potato juice base fermentation substrate obtained in step 4) at an inoculation rate of 2% to 6%, and let it ferment statically at a constant temperature of 37 to 45°C. When the pH of the fermentation liquid drops to 4.0 to 5.0, the fermentation is stopped.

[0015] 7) Finished product preparation: After fermentation, the fermentation liquid is rapidly cooled to 2-8℃ to terminate fermentation. After homogenization and aseptic filling, the fermented potato juice product with inhibited lipoxygenase activity and good flavor is obtained.

[0016] Preferred method: Citric acid concentration of 5%, soaking time of 10 min; polyphenol addition of 1%, soluble dietary fiber addition of 2%, Fe 3+ The addition amount was 1.4%; the pasteurization conditions were 70℃ for 15 min; the centrifugation conditions were 3220×g for 20 min; the ratio of thermophilic streptococci to lactococci was 1:3; the inoculum amount was 4%; the fermentation temperature was 42℃; and the fermentation was terminated when the pH reached 4.5.

[0017] The beneficial effects of this invention are reflected in: This invention establishes a multi-dimensional regulatory system for inhibiting lipoxygenase activity through the synergistic effects of citric acid color-protecting treatment, the addition of polyphenols and soluble dietary fiber, the addition of metal ions, and fermentation with compound bacterial strains. Flavoromics analysis confirms that fermentation treatment is the core factor driving differences in metabolic profiles, and that active substances and metal ions exhibit a gradual synergistic regulatory effect. Under optimized process conditions: (1) The sensory score of fermented potato juice reached 97.22 points (out of 100), which was 26.59 points higher than that of the non-fermented group; (2) The inhibition rate of lipoxygenase activity reached 65.03%, which was 21.99% higher than that of the non-fermented group; (3) Electronic tongue detection showed that, compared with the unfermented group, the fermented group had significantly enhanced sourness, reduced saltiness, and reduced bitterness and astringency. (4) Flavor mics 3D-PCA analysis showed that the fermented group and the non-fermented group were significantly separated along the PC1 axis, with PC1 explaining 39.30% of the metabolic differences, indicating that microbial fermentation is the core reason for the differences in metabolic profiles; the optimal formulation fermentation group and the fermentation group with only added active substances clustered closely, while the group with only added Fe... 3+ The fermentation group was between the fermentation group without any added substances and the optimal formulation group, demonstrating that the active substances and metal ions exhibit a gradual synergistic regulatory effect.

[0018] The fermented potato juice prepared by this invention has a good flavor and a significantly improved inhibition rate of lipoxygenase activity, showing good prospects for industrial application. Attached Figure Description

[0019] In the attached diagram: Figure 1 This is a flowchart of the method for optimizing the flavor of fermented potato juice according to the present invention; Figure 2 A comparison chart of sensory scores for fermented and unfermented potato juice; Figure 3 A comparison of the inhibition rates of lipoxygenase activity in different treatment groups; Figure 4 Radar image of the electronic tongue for fermented potato juice; Figure 5 PCA diagram of differential metabolites in fermented potato juice. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] Furthermore, "multiple" refers to two or more. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the invention.

[0022] Example 1 1) Potato color protection: Wash and cut fresh potatoes into chunks, soak them in a 5% citric acid solution for 10 minutes to protect their color, then drain.

[0023] 2) Preparation of the basic matrix: After color protection, potato chunks are mixed with distilled water at a 1:1 (w / v) ratio. Based on the weight of potato juice, 1% polyphenols, 2% soluble dietary fiber, and 1.4% Fe³⁺ (added as soluble iron salts) are added. The polyphenols are extracted from potato peels using a colloid mill-ultrasonic co-processing method; the soluble dietary fiber is obtained by high-temperature and high-pressure processing to modify and extract the precipitate from the potato peels after polyphenol extraction. The mixture is crushed, stirred, and filtered through gauze to obtain the original potato juice solution.

[0024] 3) Pasteurization: Potato juice concentrate is pasteurized at 70℃ for 15 min.

[0025] 4) Centrifugation clarification: After sterilization, the potato juice is centrifuged at 3220×g for 20 min, and the supernatant is used as the fermentation substrate.

[0026] 5) Strain activation and compounding: Streptococcus thermophilus and Lactococcus cremoris were activated and cultured separately to prepare strains with a concentration of 1.0 × 10⁻⁶. 8 A mixed starter culture was prepared by mixing a seed culture of CFU / mL with Streptococcus thermophilus and Lactococcus lactis in a ratio of 1:3.

[0027] 6) Inoculation and fermentation: Inoculate the fermentation substrate with the mixed starter at a rate of 4% (v / v) and let it ferment at a constant temperature of 42℃. Stop fermentation when the pH drops to 4.5.

[0028] 7) Finished product preparation: The fermentation broth is rapidly cooled to 4°C to terminate fermentation, homogenized, and aseptically filled to obtain fermented potato juice.

[0029] Lipoxygenase activity inhibition rate determination: The activity was determined using a plant lipoxygenase activity assay kit. The lipoxygenase activity inhibition rate of the fermented potato juice prepared in this example reached 65.03%.

[0030] Sensory evaluation: Trained evaluators scored the potatoes based on color, aroma, flavor, and other dimensions, with a maximum score of 100. The fermented potato juice prepared in this example achieved a sensory score of 97.22.

[0031] Example 2 The operating steps were the same as in Example 1, except that: the citric acid concentration was 3%, the soaking time was 20 min; the polyphenol addition was 0.5%, the soluble dietary fiber addition was 4%, and the Fe³⁺ addition was 3%; the ratio of *Streptococcus thermophilus* to *Lactococcus lactis* was 1:1; the inoculum size was 2%; the fermentation temperature was 37℃; and fermentation was terminated when the pH reached 5.0. The resulting fermented potato juice also exhibited good flavor quality and lipoxygenase activity inhibition.

[0032] Example 3 The operating steps are the same as in Example 1, except that: the citric acid concentration is 8%, the soaking time is 5 min; the polyphenol addition is 2%, the soluble dietary fiber addition is 1%, and the Fe³⁺ addition is 0.5%; the ratio of *Streptococcus thermophilus* to *Lactococcus lactis* is 1:5; the inoculum size is 6%, the fermentation temperature is 45℃, and fermentation is terminated when the pH reaches 4.0. The resulting fermented potato juice also exhibits good flavor quality and lipoxygenase activity inhibition.

[0033] Comparative Example 1 The operating steps were the same as in Example 1, except that no polyphenols, soluble dietary fiber, or Fe³⁺ were added. The resulting fermented potato juice showed significantly lower lipoxygenase activity inhibition rates and sensory scores compared to Example 1.

[0034] Comparative Example 2 The operating steps were the same as in Example 1, except that no fermentation treatment was performed. The resulting unfermented potato juice showed significantly lower lipoxygenase activity inhibition rate and sensory scores compared to Example 1.

[0035] Test Results The test results above indicate that the fermented potato juice prepared by this method exhibits excellent performance in terms of sensory quality and lipoxygenase activity inhibition rate. Through multi-dimensional synergistic regulation via citric acid color protection treatment, addition of polyphenols and soluble dietary fiber, addition of metal ions, and fermentation with compound bacterial strains, lipoxygenase activity was effectively inhibited, significantly improving the flavor of the potato juice. Flavoromics analysis further confirmed that fermentation treatment is the core factor driving differences in the metabolic profile, and that active substances and metal ions exhibit a gradual synergistic regulatory effect.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0038] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for optimizing the flavor of fermented potato juice based on the inhibition of lipoxygenase activity, characterized in that, The process includes the following steps: potato juice is prepared after color protection treatment of potatoes, polyphenols, soluble dietary fiber and metal ions are added to it, and fermentation is carried out by inoculating with compound strains to obtain fermented potato juice.

2. The optimization method as described in claim 1, characterized in that, The color-protecting treatment involves soaking in a citric acid solution with a concentration of 3% to 8% for 5 to 20 minutes.

3. The optimization method as described in claim 1, characterized in that, The potato juice contains 0.5%–2% polyphenols, 1%–4% soluble dietary fiber, and 0.5%–3% metal ions.

4. The optimization method as described in claim 1, characterized in that, The metal ion is Fe. 3+ It is added in the form of soluble iron salts.

5. The optimization method as described in claim 1, characterized in that, The compound strain is Streptococcus thermophilus and Lactococcus lactis, with a compound ratio of 1:1 to 1:5, an inoculum amount of 2% to 6%, a fermentation temperature of 37 to 45°C, and fermentation is terminated when the pH reaches 4.0 to 5.

0.

6. The optimization method as described in claim 1, characterized in that, The color-protected potato chunks were mixed with distilled water at a ratio of 1:0.5 to 1:2 (w / v) and then crushed.

7. The optimization method as described in claim 1, characterized in that, The potato juice, after the addition of polyphenols, soluble dietary fiber and metal ions, is pasteurized at 65-85℃ for 10-30 minutes, and then centrifuged at 3000-5000×g for 10-30 minutes. The supernatant is then used as the fermentation substrate.

8. The optimization method as described in claim 1, characterized in that, The polyphenols are polyphenol extracts obtained from potato peels.

9. The optimization method as described in claim 1, characterized in that, The soluble dietary fiber is a soluble dietary fiber obtained by modified extraction from potato peel precipitate after polyphenol extraction.

10. A fermented potato juice prepared by the method according to any one of claims 1-9.

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