Method for modifying canna edulis ker starch and application of canna edulis ker starch

Abstract

The invention discloses a canna edulis ker starch modification method and application, and the method comprises the following steps: cleaning canna edulis ker, grinding into thick liquid, carrying out starch modification by adopting a microwave coupling H2O2 method, carrying out lactic acid fermentation on the modified starch and plant lactic acid bacteria, fermenting to obtain canna edulis ker lactic acid fermentation liquor, adding saccharomycetes, and carrying out alcoholic fermentation to obtain the canna edulis ker starch. And then adding acetic bacteria for acetic fermentation, ageing and clarifying to obtain the canna edulis ker vinegar. The canna edulis ker vinegar prepared by the preparation method disclosed by the invention is good in flavor and rich in probiotics; meanwhile, the lactic acid fermentation procedure is added, the acidity is increased, nutrient substances of the canna edulis ker are reserved to the maximum extent, lactic acid bacteria fermentation has a certain preservative and fresh-keeping effect, the fermentation time in the fermentation process is effectively shortened through microwave coupling H2O2 canna edulis ker starch modification, and the production time is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of brewing vinegar, and in particular to a method for modifying taro starch and application thereof. Background Art

[0002] Canna, also known as dry lotus root, banana lotus root, ginger taro, is a monocotyledonous plant of the genus Canna in the family Banana. It contains a lot of nutrients and about 60% tuber starch, and is a good raw material for brewing, fermentation, food and feed processing. However, the current development and utilization of canna is mainly based on direct feed and vermicelli production in small workshops. The scale is small, the factory development of canna products is small, the yield is low, the comprehensive development and utilization rate is low, the economic value and product added value are not high, which not only wastes resources, but also pollutes the environment. In particular, the production of vermicelli in small workshops is more serious, which makes the processing performance of canna starch poor. In food processing, when canna starch is mixed with additives or other functional ingredients, interactions will occur, resulting in flocculation, precipitation, stratification and other phenomena, affecting the stability and uniformity of the entire system. In addition, canna starch has a high gelatinization temperature and poor solubility. Therefore, it is necessary to modify its starch to change its structural characteristics.

[0003] The prior art discloses a method for extracting starch from taro, which includes the steps of filing, screening, concentration, refining, dehydration, drying and packaging. However, the starch is extracted using traditional physical methods. Since the intermolecular force between starch molecules is not strong, after the ice crystals melt, the original starch structure is difficult to restore to its initial state, and water precipitation, structural collapse and the like are prone to occur, resulting in poor stability. In addition, the traditional physical extraction process simply separates and obtains starch from taro raw materials, and does not process the starch to delay the aging process of the starch. Therefore, the extracted taro starch is easily affected by external environmental factors and aged in subsequent applications, affecting its quality and performance. In addition, there are disadvantages such as low light transmittance, which greatly limits the wide application of taro starch.

[0004] Therefore, in order to solve the above problems, a method for modifying canna starch is needed to develop canna starch products with excellent properties, increase their stability, change their solubility, and improve the yield and economic benefits of canna products. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present application provides a method for modifying taro starch, the method comprising the following steps: 1) subjecting taro pulp to microwave treatment for 10 minutes using an intelligent microwave synthesis extractor to obtain treated taro pulp; 2) adding the canna pulp treated in 1) to the prepared hydrogen peroxide solution to obtain a mixed solution, subjecting the mixed solution to a water bath treatment, and then washing the mixed solution to obtain a sample solution; The solid-to-liquid ratio of the treated taro pulp to the hydrogen peroxide solution is 1:20 (g / mL); 3) After cooling to room temperature, adjust the pH of the sample solution obtained in 2) to neutral with citric acid solution and refrigerate overnight; obtain the sample solution after overnight storage and set aside; 4) The sample solution in 3) is dried overnight and then crushed to obtain modified canna starch.

[0006] Furthermore, the concentration of the prepared hydrogen peroxide solution is 0.5% and the pH value is 12.

[0007] Furthermore, the power of the intelligent microwave synthesis extractor is 480W.

[0008] Furthermore, the water bath treatment is to heat the mixed solution in a water bath at 40°C for 2 h.

[0009] Furthermore, the drying temperature was 60°C and the drying time was 12 h.

[0010] Furthermore, after crushing, it needs to be sieved through a 60-mesh sieve.

[0011] On the other hand, the present application also provides a method for preparing taro vinegar, the preparation method comprising the following steps: (1) Lactic acid bacteria fermentation: the modified taro starch obtained above is mixed with water, the pH is adjusted to 5.5, and Lactobacillus plantarum is inoculated for lactic acid bacteria fermentation. After the fermentation is completed, a taro lactic acid fermentation liquid is obtained; The solid-liquid ratio of modified canna starch to water was 1:3 (g / mL); (2) Alcohol fermentation: After the lactic acid bacteria fermentation is completed, the lactic acid bacteria fermentation liquid is mixed with the remaining taro in a certain proportion, which is called mixed fermentation liquid; the soluble solid content of the mixed fermentation liquid is adjusted to 15%, and 5.5% of activated yeast is inoculated to carry out alcohol fermentation; The activated yeast is prepared by adding 5% of the yeast into a 6% glucose aqueous solution and activating the yeast in a water bath to obtain the activated yeast; (3) Acetic acid fermentation: When the alcohol content of the mixed fermentation liquid after alcohol fermentation reaches 6.0%vol~7.5%vol, 10% activated acetic acid bacteria is added to carry out acetic acid fermentation; The activated acetic acid bacteria is prepared by adding lyophilized acetic acid bacteria powder into physiological saline at a solid-liquid ratio of 10:5 (mg / mL), and activating the acetic acid bacteria in a water bath to obtain the activated acetic acid bacteria; (4) After the acetic acid fermentation is completed, the vinegar is filtered and the supernatant is sterilized to obtain taro vinegar.

[0012] Furthermore, the activation temperature of yeast was 37° C. and the time was 30 min; the activation temperature of acetic acid bacteria was 30° C. and the time was 30 min.

[0013] Furthermore, the temperature of alcoholic fermentation is 30°C.

[0014] On the other hand, the present application also provides an application of the above-mentioned method for modifying taro starch in the preparation of taro vinegar.

[0015] Beneficial Effects 1. The present application uses microwave-coupled H2O2 to modify taro starch. Microwaves can cause hydrogen peroxide to produce hydroxyl radicals (・OH) with extremely strong oxidizing ability. Hydroxyl radicals have a high oxidation potential and can react quickly and effectively. They have a good decomposition effect on a variety of difficult-to-degrade organic matter. Reactive oxygen species (ROS) can be produced in the reaction to degrade polysaccharides, remove lignin, increase hemicellulose dissolution, improve cellulose hydration properties, etc., increase the water holding capacity and swelling capacity of taro dietary fiber, and maximize the fermentation of lactic acid bacteria, yeast and acetic acid bacteria during its fermentation process. The alcohol fermentation process of taro vinegar is optimized by mixed fermentation of lactic acid bacteria and yeast, and taro vinegar is brewed using taro wine raw materials containing a large amount of lactic acid, thereby increasing the types and contents of flavor substances in taro vinegar, making the taro vinegar rich in flavor and soft in taste.

[0016] 2. The present invention adopts clean and efficient H2O2 modification for the first time to modify canna starch. The modification technology changes the structure and physical and chemical properties of canna starch essentially, breaks down the soluble and insoluble linear parts inside the canna starch, and promotes the canna starch to have a higher content of effective ingredients such as dietary fiber, polyphenols, starch, and non-starch polysaccharides. The canna vinegar has a good flavor and is rich in probiotics. At the same time, the lactic acid fermentation process is added to increase the acidity, and the nutrients of the canna are retained to the greatest extent. At the same time, the lactic acid bacteria fermentation has a certain antiseptic and fresh-keeping effect.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present application will become more apparent by describing in more detail the exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0019] Figure 1 It is the process roadmap for the modification of taro; Figure 2 It is the process roadmap of taro vinegar; Figure 3This is a graph for determining the acid production capacity of lactic acid bacteria; Figure 4 This is a graph showing the alcohol tolerance of the strain; Figure 5 This is the temperature measurement chart of yam alcohol fermentation Figure 6 Diagram for determination of yeast addition amount for yam alcohol fermentation Figure 7 This is the temperature measurement chart of acetic acid fermentation of banana taro Figure 8 This is the figure for determining the amount of acetic acid bacteria added to Canna canna Fig. 9 Determination of Antioxidant Capacity of Canna DETAILED DESCRIPTION The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0020] Unless otherwise specified, the experimental materials used in the following examples were purchased from the market.

[0021] Example 1 Modification of Canna Starch Select canna taro without mildew, crush it with a crusher, and grind it with a colloid mill at a ratio of 1:1 to obtain canna taro pulp. Use an intelligent microwave synthesis extractor to treat the canna taro pulp at a power of 480W for 10 minutes. Prepare a hydrogen peroxide solution of a certain concentration, and adjust the pH of the hydrogen peroxide solution with a sodium hydroxide solution. Weigh about 100g of the treated canna taro pulp in a beaker, add the prepared hydrogen peroxide solution according to a solid-liquid ratio of 1:20 (g / mL), and heat it in a water bath at 40℃ for 2 hours. After cooling to room temperature, wash with water 3-5 times, adjust the pH of the sample solution to neutral with citric acid solution, and refrigerate overnight. Dry in an oven at 60℃ for 12 hours. Grind with a cyclone mill and pass through a 60-mesh sieve.

[0022] (1) Solution pH screening The other parameters were fixed, and the pH of the solution was screened at different pH values ​​of 4, 7, and 12; (2) Hydrogen peroxide concentration screening Fixing other parameters, the concentration of hydrogen peroxide solution in the H2O2 method was adjusted to 0%, 0.5%, 1%, and 2% for screening; (3) Determination of amylose content Weigh 0.1 g of potato amylose and put it into a 100 mL volumetric flask. Add 1 mL of anhydrous ethanol to wet the sample, then add 9 mL of 1 mol / L sodium hydroxide solution. Disperse in a boiling water bath for 10 min. After rapid cooling, dilute to volume with deionized water to obtain a 1 mg / mL potato amylose standard solution.

[0023] Weigh 0.1g corn amylopectin and put it into a 100mL volumetric flask. Add 1mL of anhydrous ethanol to wet the sample, then add 9mL of 1mol / L sodium hydroxide solution, disperse it in a boiling water bath for 10min, cool it quickly, and make up the volume with deionized water to obtain a 1mg / mL corn amylopectin standard solution.

[0024] Take a total of 9 50mL volumetric flasks, add 2.5mL of 0.09mol / L sodium hydroxide solution to one of the volumetric flasks as a blank, which is recorded as the control group; the other 8 50mL volumetric flasks are numbered 1-8 respectively; Add 2.50 ml of 1 mg / mL corn amylopectin standard solution to bottle 1; add 0.25 ml of 1 mg / mL potato amylose standard solution and 2.25 ml of 1 mg / mL corn amylopectin standard solution to bottle 2; add 0.50 ml of 1 mg / mL corn amylopectin standard solution and 2.00 ml of 1 mg / mL corn amylopectin standard solution to bottle 3; add 0.75 ml of 1 mg / mL corn amylopectin standard solution and 1.75 ml of 1 mg / mL corn amylopectin standard solution to bottle 4. L; add 1.00mL of 1mg / mL corn amylopectin standard solution and 1.5mL of 1mg / mL corn amylopectin standard solution to bottle No. 5; add 1.50mL of 1mg / mL corn amylopectin standard solution and 1.00mL of 1mg / mL corn amylopectin standard solution to bottle No. 6; add 2.00mL of 1mg / mL corn amylopectin standard solution and 0.50mL of 1mg / mL corn amylopectin standard solution to bottle No. 7; add 2.50mL of 1mg / mL corn amylopectin standard solution to bottle No. 8; Then add about 25mL of deionized water, 0.25mL of 1mol / L acetic acid, and 0.5mL of iodine reagent to each bottle in turn. After making up to volume with deionized water, color development takes 20 minutes, and the absorbance is read at a wavelength of 620nm. Draw a standard curve with milligrams of amylose as the horizontal axis and absorbance as the vertical axis.

[0025] (4) Sample determination Weigh 0.1g of taro powder in a 100mL volumetric flask, add 1mL of anhydrous ethanol to wet the sample, then add 9mL of 1mol / L sodium hydroxide solution, disperse in a boiling water bath for 10min, cool rapidly, and dilute with deionized water. Take 20mL of the dispersion in a 50mL stoppered test tube, add 7~10mL of petroleum ether, shake intermittently for 10min, let stand for 15min, and remove the upper petroleum ether layer after stratification. Repeat the operation twice, take 2.50mL of the defatted alkaline dispersion in a 50mL volumetric flask, add 25mL of water, and then add 0.25mL of 1mol / L acetic acid and 0.5mL of iodine reagent in turn. Dilute with deionized water and color for 20min, and read the absorbance at a wavelength of 620 nm. Calculate the percentage of amylose according to the standard curve.

[0026] Table 1 Yield of total amylose in taro after different modification conditions Note: The numbers between different letters are significantly different, P<0.05, the same below.

[0027] It can be seen from the data in Table 1 that the concentration of hydrogen peroxide has a significant effect on the total amylose yield of modified taro (P<0.05), and the yield decreases with the increase of hydrogen peroxide concentration, indicating that high concentration of alkaline hydrogen peroxide may decompose macromolecules such as dietary fiber into small molecules such as monosaccharides and oligosaccharides.

[0028] Example 2 Screening of Preparation Parameters of Canna Vinegar (1) Screening of bacterial strains Bacterial species: Bifidobacterium adolescentis ( Bifidobacterium adolescentis )CICC 6176, Bifidobacterium animalis ( Bifidobacterium animolis )CICC 6165, Lactobacillus acidophilus (Lactobacillus)CICC 6091, Bifidobacterium bifidum ( Bifidobacterium bifidum )CICC 6168, Bifidobacterium breve( Bifidobacterium breve )CICC 6181, Bifidobacterium infantis ( Bifidobacterium infantis )CICC 6069, Bifidobacterium longum( Bifidobacterium longum )CICC 6186, Lactobacillus plantarum( Lactobacillus plantarum )CICC6002, Lactobacillus casei( Lactobacillus casei )CICC 6065, Lactobacillus fermentum( Lactobacillus fermentium )CICC 6233, Lactobacillus helveticus( Lactobacillus helveticus )CICC 6064, Lactobacillus johnsonii( Lactobacillus johnsonii )CICC 6084, Lactobacillus paracasei( Lactobacillus paracasei )CICC6227, Lactobacillus reuteri( Lactobacillus reuteri )CICC 6226, Lactobacillus rhamnosus( Lactobacillus rhamnosus )CICC 6001, Lactobacillus salivarius( Lactobacillus salivarius )CICC 23174 1) Bacteria activation Take 200 μL of the glycerol-preserved strain and inoculate it into MRS broth medium, and perform activation culture at 37°C until a small amount of precipitation appears at the bottom of the test tube. Use an inoculation loop to take a loop of lactic acid bacteria from the first-generation culture tube and streak it into the MRS agar solid plate. Repeat this step until a clearly visible single colony appears after culture at 37°C. Use an inoculation loop to take a single colony on the solid plate and inoculate it into MRS broth medium. Repeat this step until a small amount of precipitation appears after culture at 37°C. This can be used as lactic acid bacteria activation liquid.

[0029] 2) Determination of lactic acid bacteria acid production capacity Adjust the bacterial concentration to 1.0, inoculate 1 mL of bacterial activation solution in 100 mL of mRS broth medium, and culture at 37°C for 48 hours. Determine the titration acidity of 10 mL of bacterial solution. The determination method is: take 10 mL of bacterial solution and titrate with 0.1 mol / L NaOH solution. The titration end point pH is 8.2. Record the volume of NaOH solution consumed. Perform three parallel tests for each strain, and select the strain with the largest NaOH consumption for the next step of screening.

[0030] 3) Alcohol resistance screening The alcohol content of the MRS broth medium was adjusted to 6% vol and 12% vol. The concentration of the lactic acid bacteria activation solution was adjusted to 1.0, and 10% of the lactic acid bacteria activation solution was inoculated into the alcohol medium. The OD600 value of the bacterial solution was measured every 6 hours for 48 hours.

[0031] (2) Preparation of taro vinegar 1) Raw material pretreatment: Select the banana taro without mold and rot, crush the banana taro with a crusher, and grind it with a colloid mill in a 1:1 ratio to obtain banana taro pulp.

[0032] 2) Modification: The taro pulp is modified with H2O2.

[0033] 3) Lactic acid bacteria fermentation: Take out the modified taro powder, add a certain amount of drinking water, mix well, adjust the pH to 5.5, inoculate plant lactic acid bacteria for lactic acid bacteria fermentation, and obtain taro lactic acid fermentation liquid after the fermentation is completed.

[0034] from Figure 3It can be seen that the acid production capacity of different lactic acid bacteria has significant differences (P<0.05), among which CICC6002, CICC 6181, CICC 6226, CICC 6233, CICC 6065, and CICC 6226 have a NaOH consumption of fermentation bacterial suspension of more than 15.0mL. The ranking from high to low is: CICC 6002>CICC 6181>CICC 6226>L. plantarum 546>CICC 6181>CICC 6233>CICC 6065. Therefore, the above 6 strains were selected as subsequent test strains.

[0035] In the culture medium of taro pulp with an alcohol content of 6%vol, the growth of the six strains of bacteria is as follows: Figure 4 As shown in the figure, the growth trends of CICC6002, CICC 6181 and CICC 6065 were similar and relatively good. The OD value of CICC 60026 reached the maximum after 12 h of culture, indicating that the strain could grow rapidly in the medium with 6% vol alcohol concentration and was less affected by 6% vol alcohol concentration.

[0036] 4) Alcohol fermentation: After the lactic acid bacteria fermentation is completed, the lactic acid bacteria fermentation liquid is mixed with the remaining banana taro in a certain proportion, which is called mixed fermentation liquid. The soluble solid content is adjusted to 15%, 5.5% yeast is inoculated, and the fermentation temperature is set at 30℃ for alcohol fermentation.

[0037] Taking alcohol content as an indicator, the effects of different fermentation temperatures (28℃, 30℃, 32℃, 34℃, 36℃) and yeast inoculation amounts (2.5%, 3.5%, 4.5%, 5.5%, 6.5%) on its alcohol fermentation were investigated.

[0038] The starch content of banana canna is suitable as a raw material for alcohol fermentation. After the saccharification process, the reducing sugar content of banana canna saccharification liquid increases, which can meet the basic requirements of alcohol fermentation. During the alcohol fermentation process, yeast undergoes glycolysis under anaerobic conditions, converting glucose in the substrate into pyruvate. Pyruvate is acted upon by the decarboxylase in the yeast to produce acetaldehyde, which is then reduced to produce alcohol. Figure 5 It can be seen that the alcohol content increases with the increase of fermentation temperature at 28~30℃. When the fermentation temperature is too low, the mycelium grows slowly and the alcohol fermentation is incomplete, resulting in a low alcohol content. When the fermentation temperature exceeds 30℃, the alcohol content decreases. This is because high temperature inhibits the growth and reproduction of yeast. Therefore, the optimal alcohol fermentation temperature is 30℃. Figure 6It can be seen that when the yeast addition amount is 5.5%, the alcohol content reaches its highest as the fermentation time changes. When the yeast addition amount is too low, the alcohol content is low, which may be due to insufficient yeast concentration, resulting in incomplete fermentation. As the yeast addition amount increases, the alcohol content also increases, and then decreases. This is because the yeast addition amount is too high, resulting in the reuse of its nutrients such as sugars, and it will ferment other substances, causing its alcohol content to decrease. Therefore, the optimal yeast addition amount is 5.5%.

[0039] 5) Acetic acid fermentation: When the alcohol content of the fermentation liquid reaches 6.0%vol~7.5%vol, 10% acetic acid bacteria is added for acetic acid fermentation.

[0040] The acetic acid fermentation process is that acetic acid bacteria react with alcohol to produce acetic acid under aerobic conditions. Figure 7 It can be seen that when the fermentation temperature is too low, the bacterial growth rate is slow, the acetic acid fermentation is incomplete, and the acetic acid content is low. When the fermentation temperature is 36°C, the acetic acid content decreases with the increase of temperature. This is because the activity of alcohol dehydrogenase and acetaldehyde dehydrogenase is inhibited in a high temperature environment, the rate of ethanol oxidation to acetic acid is reduced, and the acetic acid content decreases. Therefore, the optimal fermentation temperature is 34°C. Figure 8 It can be seen that the acetic acid content also decreases with the increase of the acetic acid bacteria inoculation amount. If the acetic acid bacteria inoculation amount is appropriately increased, the acetic acid fermentation rate will increase accordingly, but when an excessive amount of acetic acid bacteria is added, the acetic acid content cannot be increased. This is because the nutrients required for the growth and reproduction of excessive acetic acid bacteria also increase, and the acetic acid fermentation process is inhibited, resulting in a decrease in acetic acid content. Therefore, the optimal acetic acid bacteria addition amount is 10%.

[0041] 6) Activation of yeast: a certain amount of yeast was put into a 6% glucose aqueous solution and activated in a 37°C water bath for 30 minutes; 7) Activation of acetic acid bacteria: Take a certain amount of freeze-dried powder of acetic acid bacteria according to the proportion, add it to a certain amount of physiological saline, and activate it in a 30℃ water bath for 30 minutes; 8) After the acetic acid fermentation is completed, the fermentation liquid is filtered and the supernatant is sterilized to obtain taro vinegar.

[0042] Taking the acidity of acetic acid content as an indicator, the effects of fermentation temperature (32℃, 34℃, 36℃, 38℃, 40℃), inoculation amount of Acetobacter pasteurianus (5%, 10%, 15%, 20%, 25%), and fermentation time (4d, 6d, 8d, 10d, 12d) on acetic acid fermentation were investigated.

[0043] The process route adopted by the present invention is as follows Figure 2 shown.

[0044] Example 3 Determination of Canna Vinegar Index Determination of soluble solids and pH: refer to GB / T 15038 "General analysis method for wine and fruit wine".

[0045] 1) Determination of total acid (in terms of acetic acid): Take an appropriate amount of fermentation liquid, centrifuge it, remove the precipitate and perform ultrasound, take 5 mL of taro vinegar sample solution, add 50 mL of ultrasonically treated distilled water, and titrate with 0.1 mol / L NaOH solution until the pH reaches 8.20. The calculation formula is as follows: X = [(V1-V2) × c × 60] / V In the formula: X is the total acid (measured in acetic acid), in g / L; V1 is the consumption of NaOH solution in the sample, in mL; V2 is the consumption of NaOH solution in the blank group, in mL; V is the volume of the sample to be measured, in mL; C is the concentration of the NaOH standard solution, in mol / L; 60 is the relative molecular mass of acetic acid, in g / moL.

[0046] The taro vinegar solution was centrifuged to remove the precipitate, and 2 mL of the supernatant was filtered and tested.

[0047] Preparation of organic acid standard solution: Accurately weigh 0.20 g oxalic acid, 0.20 g tartaric acid, 1.00 g lactic acid, 5.00 g acetic acid, 0.50 g citric acid, and 0.20 g succinic acid in a 100 mL volumetric flask, filter through a 0.22 μm water filter membrane and set aside.

[0048] Table 2 Organic acid index of taro vinegar From the data in Table 2, we can see that the organic acid indicators of taro vinegar are citric acid 153.2±3.65 mg / L, lactic acid 3017.84±10.11 mg / L, oxalic acid 107.42±12.65 mg / L, tartaric acid 65.74±8.45 mg / L, acetic acid 41009.88±13.1 7 mg / L, succinic acid 210.45±4.01 mg / L, and total acid 444564.53 mg / L.

[0049] Table 3 Comparison of fermentation time of taro vinegar From the data in Table 3, it can be seen that the fermentation time of canna vinegar after microwave coupling with H2O2 is shortened to 7 days. This may be because microwave energy can cause hydrogen peroxide to produce hydroxyl free radicals (・OH) with extremely strong oxidizing ability. Hydroxyl free radicals have a very high oxidation potential and can react quickly and effectively. They have a good decomposition effect on a variety of difficult-to-degrade organic matter. In the reaction, they can produce reactive oxygen species (ROS) to degrade polysaccharides, remove lignin, increase hemicellulose solubility, improve cellulose hydration properties, etc., increase the water holding capacity and swelling capacity of canna dietary fiber, and maximize the fermentation of lactic acid bacteria, yeast and acetic acid bacteria during the fermentation process.

[0050] 2) Clarity: The transmittance T680 and absorbance A420 values ​​are used to indicate the clarity of the canna vinegar.

[0051] 3) Determination of total phenols The total phenol content was determined by the Folin-ciocalteu method. Standard curve: Prepare a gallic acid standard solution with a mass concentration of 0.1 mg / mL, accurately add 0.50, 1.00, 1.50, 2.00, 2.50, and 3.00 mL of gallic acid solution to a 25 mL stoppered test tube, add 1.25 mL of Folin-ciocalteu reagent and 3.75 mL of 20% sodium carbonate solution in sequence, dilute to the 25 mL mark with distilled water, react at 30 °C for two hours, and use distilled water instead of the sample as a blank control group, and measure the absorbance at 765 nm. Make a standard curve and determine the regression equation.

[0052] Table 4 Physical and chemical indexes of taro vinegar From the data in Table 4, it can be seen that the pH value of taro vinegar is 2.89±0.06, the total acid is 44.45±0.13 g / L, and the clarity is 95.45±0.23. It is possible that microwave coupling of H2O2 causes some hydroxyl groups to be oxidized into aldehyde groups, carboxyl groups and other functional groups, which reduces the degree of polymerization of starch, increases the hydrophilicity and solubility of starch, and improves its transparency.

[0053] 4) Determination of DPPH free radical scavenging ability. Pipette 0.2 mL of the centrifuged mango peel fermentation liquid, add 31 µg / mL DPPH solution, shake thoroughly, place in the dark at room temperature for 0.5 h, and measure the absorbance at 517 nm. Use pure water instead of mango peel fermentation liquid as blank, and use pure water instead of DPPH solution for zero adjustment.

[0054] DPPH clearance rate (%) = [(s-sb) / (c-cb)] × 100% In the formula: s——DPPH·free radical scavenging ability absorbance, sb——sample interference test absorbance (zero adjustment), c——DPPH pure water solution absorbance, cb——pure water absorbance (zero adjustment).

[0055] Table 5 HPLC conditions The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for modifying canna starch, characterized in that: The specific steps of the method include: 1) treating the taro pulp with microwaves for 10 min using an intelligent microwave synthesis extractor to obtain treated taro pulp; 2) adding the canna pulp treated in 1) to the prepared hydrogen peroxide solution to obtain a mixed solution, subjecting the mixed solution to a water bath treatment, and then washing the mixed solution to obtain a sample solution; The solid-to-liquid ratio of the taro pulp to the hydrogen peroxide solution is 1:20 (g / mL); 3) After cooling to room temperature, the pH of the sample solution obtained in 2) is adjusted to neutral with a citric acid solution, and refrigerated overnight; the sample solution obtained after overnight storage is set aside; 4) The sample solution in 3) is dried overnight and then crushed to obtain modified canna starch.

2. The method according to claim 1, characterized in that The concentration of the prepared hydrogen peroxide solution is 0.5%, and the pH value is 12.

3. The method according to claim 1, characterized in that The power of the intelligent microwave synthesis extraction instrument is 480W.

4. The method according to claim 1, characterized in that: The water bath treatment is to heat the mixed solution in a water bath at 40° C. for 2 h.

5. The method according to claim 1, characterized in that The drying temperature is 60° C. and the drying time is 12 hours.

6. The method according to claim 1, characterized in that After the pulverization, the powder needs to be sieved through a 60-mesh sieve.

7. A method for preparing taro vinegar, characterized in that: The preparation method comprises the following steps: (1) Lactic acid bacteria fermentation: the modified taro starch obtained in claim 1 is mixed with water, the pH value is adjusted to 5.5, and Lactobacillus plantarum is inoculated to carry out lactic acid bacteria fermentation, and after the fermentation is completed, a taro lactic acid fermentation liquid is obtained; The solid-liquid ratio of the modified taro starch to water is 1:3 (g / mL); (2) Alcohol fermentation: After the lactic acid bacteria fermentation is completed, the lactic acid bacteria fermentation liquid is mixed with the remaining taro in a certain proportion, which is called mixed fermentation liquid; the soluble solid content of the mixed fermentation liquid is adjusted to 15%, and 5.5% of activated yeast is inoculated to carry out alcohol fermentation; The activated yeast is prepared by adding 5% of the yeast into a 6% glucose aqueous solution and activating the yeast in a water bath to obtain the activated yeast; (3) Acetic acid fermentation: When the alcohol content of the mixed fermentation liquid after alcohol fermentation reaches 6.0%vol~7.5%vol, 10% activated acetic acid bacteria is added to carry out acetic acid fermentation; The activated acetic acid bacteria is prepared by adding lyophilized acetic acid bacteria powder into physiological saline at a solid-liquid ratio of 10:5 (mg / mL), and activating the acetic acid bacteria in a water bath to obtain the activated acetic acid bacteria; (4) After the acetic acid fermentation is completed, the vinegar is filtered and the supernatant is sterilized to obtain taro vinegar.

8. The preparation method according to claim 7, characterized in that: The activation temperature of the yeast is 37° C. and the time is 30 min; the activation temperature of the acetic acid bacteria is 30° C. and the time is 30 min.

9. The preparation method according to claim 7, characterized in that: The temperature of the alcohol fermentation is 30°C.

10. Use of the method for modifying canna starch as claimed in claim 1 in preparing canna vinegar.

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