Method for inhibiting retrogradation of mashed potatoes through cooperation of microwaves and beta-amylase

Abstract

The invention provides a method for inhibiting retrogradation of mashed potatoes through cooperation of microwaves and beta-amylase, and belongs to the technical field of food processing. Comprising the following steps: fresh potatoes are cleaned, peeled and diced, and are immersed into 0.05 wt% ascorbic acid for color protection; after cooking and curing, draining and cooling, and stirring into uniform mud; putting the mashed potatoes into a microwave extraction instrument device, heating, stirring and performing enzymolysis according to a set program, and finally performing high-temperature enzyme deactivation to obtain a mashed potato finished product. Compared with mashed potatoes which are not subjected to enzymolysis treatment, the anti-retrogradation effect is improved by 71% after the mashed potatoes are subjected to traditional water bath enzymolysis treatment for 30 min, the anti-retrogradation effect is improved by 75% after microwave combined enzymolysis treatment for 20 min, and the flavor of the potatoes is reserved. The microwave combined enzymolysis technology optimizes the traditional mashed potato production process, the microwave technology is introduced to improve the enzymolysis efficiency, the retrogradation resistance of the mashed potatoes is further improved, the processing method for efficiently prolonging the quality guarantee period of the mashed potatoes is provided, the retrogradation problem of the mashed potatoes is solved, and conditions are provided for mashed potato product production and deep processing.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing and provides a method for inhibiting the retrogradation of potato mash by using microwaves in coordination with beta-amylase. Background Art

[0002] Mashed potatoes are a nutritious, delicious and delicate food with a wide history of consumption around the world. Traditional mashed potatoes are popular among people for their high starch content, rich vitamins and dietary fiber. In recent years, with the advancement of agricultural and food processing technology, the mashed potato industry has also developed rapidly. Through scientific proportioning and careful blending, many new types of mashed potato products have emerged, such as mixed mashed potatoes with vegetables, meat, cheese and other ingredients, as well as seasoned mashed potatoes of various flavors. This not only enriches the nutritional content of the product, but also greatly enhances the flavor level and taste diversity. The output is constantly increasing, and it has broad market prospects.

[0003] However, there are many challenges in potato processing, among which starch retrogradation is particularly prominent. Starch retrogradation can lead to a series of adverse consequences, such as hardening of the taste, deterioration of quality, and stickiness of the product, which not only greatly increases the difficulty of production, but also reduces consumer acceptance. In addition, unstable starch structure can cause product deterioration during storage and transportation, resulting in discoloration, taste change, and odor. The easy retrogradation of potato mash seriously limits its eating experience and further development in the food industry.

[0004] Enzymatic modification has attracted widespread attention as an effective means to solve the problem of retrogradation. By selecting suitable amylases, such as α-amylase or β-amylase, specific parts of the starch chain can be degraded in a targeted manner, the molecular weight and molecular structure of the starch can be changed, and the retrogradation process can be regulated. Among them, β-amylase has a greater advantage in maintaining product quality due to its mild action characteristics. β-amylase acts on 1-4 glycosidic bonds in units of disaccharides. Therefore, by regulating the enzymatic conditions, the degree of starch hydrolysis can be accurately controlled. In addition, this modification method can maintain the original taste and flavor of the product while improving the stability and shelf life of the product. However, although the use of enzymatic technology alone has certain effects, it still has some shortcomings. For example, the enzymatic reaction rate is relatively slow, and it takes a long time to activate to achieve better results.

[0005] In recent years, microwave heating has been widely used to quickly heat / reheat various foods and significantly improve food quality. Compared with traditional conduction heating, microwave treatment can significantly change the structure and properties of starch in a short time and improve heating efficiency. Regarding the mechanism of microwave anti-retrogradation effect on starch, it is generally believed that thermal effect is the main reason for starch chain degradation, structure and property changes. Studies have shown that microwave treatment can more effectively inhibit the reassociation of disordered molecular chains of lotus seed starch (Wang, Jiang, Guo, Zheng, & Zhang, 2021). Considering that microwave treatment can cut starch chains (B2 and B3) and release more short-chain starch, these short-chain starches will help stabilize starch gels and inhibit retrogradation. In addition, microwave pretreatment can provide a more favorable environment for enzymatic hydrolysis by changing the morphology and internal structure of starch granules. However, microwave heating alone has disadvantages such as uneven heating, local overheating and resulting in "hot spots", and easy loss of water. Summary of the invention

[0006] In order to solve the problems of slow reaction speed, long activation time and easy local overheating caused by using the above-mentioned enzymatic hydrolysis technology alone, the purpose of the present invention is to provide a method for inhibiting the retrogradation of potato mash by using microwaves in coordination with β-amylase, so that the anti-retrogradation effect of potato mash is better than that of a single treatment method. At the same time, the energy consumption is reduced due to the shortened treatment time, and the texture of potato mash can be made more uniform, achieving a better anti-retrogradation effect, thereby improving production efficiency and product quality.

[0007] The present invention is different from the previous technical research. Based on the physical properties of mashed potatoes, the present invention adopts a combination of microwave and enzymatic hydrolysis multiple modification technology to achieve a more accurate starch property regulation method, and combines factors such as microwave power, microwave heating time and enzymatic hydrolysis degree to solve the problems of mashed potatoes retrogradation and unstable quality in traditional processing methods. In the technical field of exploring starch anti-retrogradation, most of the existing technologies are limited to using amylase or microwave alone to deal with this problem. As for the use of amylase alone, it relies on its ability to specifically hydrolyze starch molecules, breaks the glycosidic bonds inside the starch, and converts large-molecule starch into smaller fragments, thereby interfering with the orderly arrangement of molecules in the starch retrogradation process, and then plays a certain anti-retrogradation effect. When microwaves are used alone, they mainly use the thermal effect they produce to make the water molecules in the starch granules vibrate violently, achieve rapid gelatinization, change the initial state of starch, and delay the retrogradation rate in a short period of time.

[0008] However, there are indeed some difficulties when considering the combination of amylase and microwave for starch anti-retrogradation. On the one hand, from the perspective of the mechanism of action, amylase changes the starch structure through biochemical hydrolysis reactions, while microwaves change the starch state based on physical thermal effects. In order for them to work synergistically to achieve the ideal anti-retrogradation effect, many parameters such as time, intensity, and enzymatic hydrolysis dosage must be precisely coordinated. For example, when using α-amylase to hydrolyze potato mash, it is difficult to control the hydrolysis efficiency, and over-hydrolysis may occur.

[0009] The technical solution of the present application provides a method for inhibiting potato mash retrogradation by using microwaves in cooperation with β-amylase. The method is a process for making potato mash, which involves microwave treatment and enzymatic hydrolysis. The specific steps are as follows:

[0010] S1. Raw material pretreatment: Select fresh potatoes, wash and peel them, cut them into pieces, and immerse them in color-protecting liquid;

[0011] S2 cooking and cooking: the above potato pieces are cooked and cooked; the cooked potato pieces are removed and drained and placed to cool;

[0012] S3. Preparation of mashed potatoes: When the potato pieces are cooled to below 30°C, they are made into a uniform puree;

[0013] S4. Microwave combined enzymatic hydrolysis: adding β-amylase preparation to mashed potatoes, placing the mashed potatoes in a microwave extractor, stirring, and performing microwave treatment and enzymatic hydrolysis;

[0014] S5. High temperature enzyme inactivation: subjecting the mashed potatoes to high temperature enzyme inactivation treatment; after enzyme inactivation, a finished product of the mashed potatoes is obtained.

[0015] In some specific embodiments, the cutting in step S1 preferably cuts the potatoes into cubes with a side length of 1.5 to 2.5 cm.

[0016] Furthermore, the color protection liquid in step S1 is ascorbic acid with a mass fraction of 0.05%, and the solvent of the ascorbic acid is water; and the time for entering the color protection liquid is 10 to 20 minutes.

[0017] Furthermore, in step S2, the cooking temperature is 100° C. and the time is 15 to 20 minutes; and the cooling time is 10 to 20 minutes.

[0018] Furthermore, the preparation of mashed potatoes in step S3 is to mash / press / whip the potatoes into a puree, and the obtained mashed potatoes have a uniform texture; in some specific embodiments, the mashing is preferably performed in a blender.

[0019] Furthermore, in step S3, in order to prevent continuous heat generation and uneven whipping / stirring, the whipping / stirring process of the mashed potatoes needs to be performed intermittently; the whipping / stirring time and interval are adjusted according to different amounts of mashed potatoes to ensure a good stirring effect;

[0020] In some specific embodiments, the mixture is first stirred for 5 minutes (stopped every 30 to 45 seconds) until there are no obvious particles and the mixture is in a uniform paste state, and then stirred continuously for 1 minute.

[0021] Further, in step S4, a temperature program is set in advance in the microwave extractor, and the temperature program is: ① first control the temperature to 25-34°C, the time to 1 min, and the power to 400W; ② control the temperature to 34-38°C, the time to 1 min, and the power to 400W; ③ control the temperature to 38-42°C, the time to 1 min, and the power to 400W; ④ control the temperature to 42-46°C, the time to 2 min, and the power to 400W; ⑤ control the temperature to 46-48°C, the time to 5 min, and the power to 400W; ⑥ finally control the temperature to 48-50°C, the time to 5-25 min, and the power to 200W.

[0022] Further, in step S4, the solvent of the β-amylase preparation is water; the addition ratio of the β-amylase preparation according to the enzyme activity is 25U / g potato puree, that is, the usage ratio of the β-amylase preparation to potato puree is 25U enzyme: 1g potato puree; the pH of the β-amylase preparation is controlled at 6-6.5.

[0023] Furthermore, in step S4, the stirring speed is 250-350 rpm, and the stirring time is 10-30 min.

[0024] Furthermore, in step S5, the high temperature enzyme inactivation treatment is: the potato mash is treated at a high temperature of above 100° C. for 10 to 20 minutes to inactivate the enzyme.

[0025] In some specific embodiments, to ensure complete inactivation of the enzyme, subpackaging is usually performed, and the high-temperature enzyme inactivation treatment is: every 100 g of potato mash is subjected to a high-temperature enzyme inactivation treatment at above 100° C. for 10 to 20 minutes.

[0026] The second technical solution of the present application provides a finished potato puree product prepared by the method of inhibiting potato puree regeneration by using the above-mentioned microwave in conjunction with β-amylase.

[0027] Furthermore, the moisture content of the prepared potato mash product is 75% to 85%.

[0028] Compared with the prior art, this application has at least the following beneficial effects:

[0029] (1) The present invention provides a method for inhibiting potato mash regeneration by microwave-assisted enzymatic hydrolysis from the perspectives of microwave power and microwave heating time. This method avoids problems such as excessive enzymatic hydrolysis and loss of nutrients that may occur in traditional treatment methods, and effectively improves the quality stability of potato mash.

[0030] (2) The present invention uses microwave heating to coordinate enzymatic hydrolysis of potato mash, which significantly shortens the processing time and improves production efficiency compared with traditional enzymatic hydrolysis methods. Microwave heating causes more internal amylopectin chains to be cleaved and released, while further enhancing the dilution effect of enzymatic hydrolysis on the surface of potato starch particles, thereby effectively inhibiting retrogradation. At the same time, by accurately controlling the microwave power and heating time, the enzymatic hydrolysis effect can be further optimized to ensure that the potato mash maintains a good taste and texture for a long time.

[0031] (3) The method of the present invention does not require the addition of additional chemical inhibitors, will not have an adverse effect on the flavor of mashed potatoes, and does not pose a food safety hazard, thus satisfying people's pursuit of healthy food. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Texture changes of potato mash after microwave heating and no enzymatic hydrolysis (a) 0d; (b) 7d;

[0033] Figure 2 The rheological properties of potato mash treated with microwave heating and no enzymatic hydrolysis;

[0034] Figure 3 Texture changes of potato mash treated with microwave-assisted enzymatic hydrolysis: (a) hardness characteristics; (b) viscosity characteristics;

[0035] Figure 4 Rheological properties of microwave-assisted enzymatic hydrolysis of potato mash.

[0036] Figure 5 Temperature profile for heating the sample;

[0037] Figure 6 The experimental method and mechanism diagram of this application. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0039] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0040] Comparative Example 1: Production of mashed potato products by microwave heating + no enzymatic hydrolysis

[0041] The mashed potato production steps used in this embodiment are as follows:

[0042] S1 Raw material pretreatment: select 1 kg of fresh potatoes, wash and peel them, cut them into cubes of about 2 cm*2 cm*2 cm, immerse them in color protection liquid (0.05% ascorbic acid by mass) for 10 minutes for later use;

[0043] S2 Steaming and cooking: Put the cut potato cubes into a steamer and steam and cook them at 100°C for 15 minutes. Take out the cooked potatoes, drain them thoroughly, and place them in a well-ventilated place to cool naturally for 10 minutes.

[0044] S3 Whipping: When the temperature of the potato puree is lowered to below 30° C., the potato puree is placed in a blender for whipping / mixing; the potato puree needs to be stirred / mixed intermittently during the stirring / mixing process, first using inching stirring for 5 minutes (stopping every 30 to 45 seconds) until there are no obvious particles and the puree is uniform, then switching to continuous stirring for 1 minute to whip into a uniform puree;

[0045] S4 Microwave Heating: Place 400 g of mashed potatoes in a microwave extractor and set a temperature control program for the microwave extractor according to the heating temperature curve (e.g. Figure 5 ). Start the program and stir at 300 rpm for 20 minutes.

[0046] S5 high temperature sterilization: the mashed potatoes are subjected to high temperature sterilization treatment at 100° C. for 10 minutes. After the sterilization treatment, the finished mashed potatoes are obtained.

[0047] At this time, the potato puree product obtained above can be packaged and stored: the prepared potato puree sample is vacuum-sealed and stored at 4°C.

[0048] Comparative Example 2: Production of mashed potato products by water bath heating + no enzymatic hydrolysis

[0049] The mashed potato production steps used in this embodiment are as follows:

[0050] S1 Raw material pretreatment: select 1 kg of fresh potatoes, wash and peel them, cut them into cubes of about 2 cm*2 cm*2 cm, immerse them in color protection liquid (0.05% ascorbic acid by mass) for 10 minutes for later use;

[0051] S2 Steaming and cooking: Put the cut potato cubes into a steamer and steam and cook them at 100°C for 15 minutes. Take out the cooked potatoes, drain them thoroughly, and place them in a well-ventilated place to cool naturally for 10 minutes.

[0052] S3 Whipping: When the temperature of the potato puree is lowered to below 30° C., the potato puree is placed in a blender for whipping / mixing; the potato puree needs to be stirred / mixed intermittently during the stirring / mixing process, first using inching stirring for 5 minutes (stopping every 30 to 45 seconds) until there are no obvious particles and the puree is uniform, then switching to continuous stirring for 1 minute to whip into a uniform puree;

[0053] S4 Conventional water bath heating: 400 g of mashed potatoes were placed in a 1 L beaker and placed in a conventional water bath at 50 °C, while the stirrer was stirred at 300 rpm for 20 min.

[0054] S5 high temperature sterilization: the mashed potatoes are subjected to high temperature sterilization treatment at 100° C. for 10 minutes. After the sterilization treatment, the finished mashed potatoes are obtained.

[0055] At this time, the potato puree product obtained above can be packaged and stored: the prepared potato puree sample is vacuum-sealed and stored at 4°C.

[0056] Example 1 Production of mashed potato products by microwave heating combined with enzymatic hydrolysis

[0057] The mashed potato production steps used in this embodiment are as follows:

[0058] S1 Raw material pretreatment: select 1 kg of fresh potatoes, wash and peel them, cut them into cubes of about 2 cm*2 cm*2 cm, immerse them in color protection liquid (0.05% ascorbic acid by mass) for 10 minutes for later use;

[0059] S2 Steaming and cooking: Put the cut potato cubes into a steamer and steam and cook them at 100°C for 15 minutes; take out the cooked potatoes, drain them thoroughly, and then place them in a well-ventilated place to cool naturally for 10 minutes;

[0060] S3 whipping: when the mashed potatoes are cooled to below 30°C, they are placed in a blender for whipping / stirring; the mashed potatoes need to be whipped / stirred intermittently, first using inching stirring for 5 minutes (stopping every 30 to 45 seconds) until there are no obvious particles and the mash is in a uniform paste state, then switching to continuous stirring for 1 minute to whip into a uniform paste state;

[0061] S4 Microwave enzymatic hydrolysis: 400 g of mashed potatoes were placed in a microwave extractor, and a temperature control program (such as Figure 5 ). Then, an appropriate amount of β-amylase (25 U / g potato puree) was added, and the microwave extraction program was started while the stirrer was stirred at 300 rpm for 20 min to ensure sufficient enzymatic hydrolysis.

[0062] S5 high temperature sterilization: the mashed potatoes are subjected to high temperature sterilization and enzyme inactivation treatment at 100° C. for 10 minutes, and a finished mashed potato product is obtained after the sterilization and enzyme inactivation treatment.

[0063] At this time, the finished potato puree can be packaged and stored: the prepared potato puree sample is vacuum-sealed and stored at 4°C.

[0064] Example 2 Production of mashed potato products using conventional water bath heating combined with enzymatic hydrolysis

[0065] S1 Raw material pretreatment: select 1 kg of fresh potatoes, wash and peel them, cut them into cubes of about 2 cm*2 cm*2 cm, immerse them in color protection liquid (0.05% ascorbic acid by mass) for 10 minutes for later use;

[0066] S2 Steaming and cooking: Put the cut potato cubes into a steamer and steam and cook them at 100°C for 15 minutes; take out the cooked potatoes, drain them thoroughly, and then place them in a well-ventilated place to cool naturally for 10 minutes;

[0067] S3 whipping: when the mashed potatoes are cooled to below 30°C, they are placed in a blender for whipping / stirring; the mashed potatoes need to be whipped / stirred intermittently, first using inching stirring for 5 minutes (stopping every 30 to 45 seconds) until there are no obvious particles and the mash is in a uniform paste state, then switching to continuous stirring for 1 minute to whip into a uniform paste state;

[0068] S4 Traditional water bath combined with enzymatic hydrolysis: 400 g of potato puree was placed in a 1 L beaker, placed in a traditional water bath at 50 °C, an appropriate amount of β-amylase (25 U / g potato puree) was added, and the agitator was stirred at 300 rpm for 20 min to ensure sufficient enzymatic hydrolysis.

[0069] S5 high temperature sterilization: the mashed potatoes are subjected to high temperature sterilization and enzyme inactivation treatment at 100° C. for 10 minutes, and a finished mashed potato product is obtained after the sterilization and enzyme inactivation treatment.

[0070] At this time, the finished potato puree can be packaged and stored: the prepared potato puree sample is vacuum-sealed and stored at 4°C.

[0071] Example 3 Texture and rheological properties of mashed potatoes

[0072] The finished mashed potatoes prepared by different methods in Example 1, Example 2 and Comparative Example 1, Comparative Example 2 were used as test objects, and the regeneration process was simulated by storing them for different lengths of time. After the simulation, the texture and rheological properties of the mashed potatoes prepared in this example were measured.

[0073] The quality indicators of the produced potato mash are textural properties and rheological properties, the definitions and analysis methods of which are as follows:

[0074] (1) Texture properties: The texture properties of the product have been confirmed to be an important factor affecting the quality, among which there is a close correlation between the hardness of starch gel and its retrogradation phenomenon. The specific operation is as follows: the sample is equilibrated to room temperature before measurement, and the texture is measured using a texture analyzer TPA (TA-XT2i, Shanghai Boxin Industrial Development Co., Ltd., Shanghai, China) and a P / 36R cylindrical probe. The speed before the test is 2.0 mm / s, the test speed is 1.0 mm / s, the speed after the test is 2.0 mm / s, the target mode deformation (70%), the interval time is 3.0 s, and the trigger force is 5.0 g. Each sample is measured 5 times and then the average value is calculated.

[0075] (2) Dynamic rheological properties: The effect of adding microwave combined with enzymatic hydrolysis on the short-term recovery of potato mash was determined using samples stored at 4°C for 8 h. The samples were equilibrated to room temperature for 30 min before measurement to inhibit the progression of short-term recovery. After equilibration to room temperature, the gel sample was loaded into the middle of the sample plate and the edge sample traces were removed after the press was pressed. After equilibration at 25°C for 2 min, the gel was dynamically scanned at a frequency of 0.1–100 rad / s in the linear viscoelastic region (0.25% strain) to determine the storage modulus (G′) and loss modulus (G″).

[0076] The potato mash stored for 0 and 7 days in the comparative example was used to simulate the regeneration process. The texture and rheological properties of the mashed potatoes were listed in Figure 1 , Figure 2 The potato mash stored for 0, 7, 14, 21, and 28 days in Example 1 and Example 2 was used to simulate the retrogradation process, and the texture and rheological properties were listed in Figure 3 , Figure 4 (In the figure, MW means microwave heating treatment; WB means water bath heating treatment. MW-10 means microwave heating for 10 min; WB-10 means traditional water bath heating for 10 min; BHMW-10 means microwave combined with enzymatic hydrolysis treatment for 10 min; BHWB-10 means traditional water bath combined with enzymatic hydrolysis treatment for 10 min; similarly, the numbers represent the processing time).

[0077] First by Figure 1 and Figure 3It can be seen that microwave heating will make mashed potatoes have lower hardness, stickiness, chewiness and adhesiveness. After 7 days of aging, all sample groups showed obvious aging. Especially for mashed potatoes that have not been treated with enzymes, the hardness showed a significant increase in the early stage of storage (the hardness increased from 20.53gf to 31.50gf at 3d), and the aging was obvious. Compared with mashed potatoes that have not been treated with enzymes, the anti-aging effect of traditional water bath enzymatic hydrolysis for 30min (sealed and stored at 4℃ for 14d) increased by 70%, while the anti-aging effect of microwave combined enzymatic hydrolysis for 20min increased by 75%, and the potato flavor was still retained. This proves that β-amylase and microwave technology have a good effect on the anti-aging of mashed potatoes. In addition, during the storage process, the viscosity of mashed potato samples that have not been treated with enzymes first increased and then decreased, while the samples that have been treated with enzymes showed a trend of continuous slow increase. This phenomenon is due to the retrogradation of starch in unhydrolyzed potato mash, which causes the texture of the potato mash to become harder and is accompanied by a decrease in viscosity. This is related to the reduction in the particle size of potato mash after enzymatic hydrolysis. Studies have shown that small-sized particles usually have lower viscosity. As the storage time increases, the starch in the traditional water bath treatment group begins to undergo a retrogradation process, that is, the starch molecules rearrange to form an ordered structure, resulting in an increase in viscosity. However, when the storage time reaches 21 days, the viscosity of the microwave enzymatic hydrolysis group begins to be significantly lower than that of the traditional water bath treatment group. This is because the starch-water mixture sample under microwave heating has a stronger dielectric response, the starch gelatinization is more thorough, and the formed colloidal solution can better maintain its stability and fluidity during the retrogradation process, thus showing a relatively low viscosity.

[0078] On the other hand, contrast Figure 2 and Figure 4It can be seen that the sample groups heated by microwave and microwave combined with enzymatic hydrolysis both showed weak gel properties. The potato mash without heating and enzymatic hydrolysis had higher G' and G" values ​​at the same shear rate, showing relatively strong viscosity characteristics, which may be related to the higher ratio of starch content in the whole system. When the starch was treated with microwaves, G' and G" decreased significantly, indicating that microwave treatment weakened the gel structure of the starch paste. This is because microwaves can cause the starch chain length to break and reduce the proportion of long-chain starch molecules, which are important components for maintaining the stability of the permanent connection area of ​​the gel. For the starch gel in the microwave combined enzymatic hydrolysis group, the addition of amylase significantly reduced its G' and G", and this downward trend became more obvious as the enzymatic hydrolysis time prolonged. This result was in line with expectations. Starch was hydrolyzed by enzymes to generate monosaccharides, thereby reducing the viscosity of the system. In particular, the introduction of microwave technology further enhanced the dilution effect of enzymatic hydrolysis on the viscoelasticity of potato mash. This is because microwave irradiation increases the orientation effect between the enzyme active site and the substrate in the hydrolysis system, making the enzymatic hydrolysis reaction more efficient and specific. Therefore, in the microwave system, β-amylase has a higher degree of enzymatic hydrolysis of potato mash. At the same time, the generated sugar competes with starch for water molecules, further reducing the viscosity of the gel. In addition, the low molecular weight dextrin after enzymatic hydrolysis interferes with the interaction between starches and inhibits retrogradation.

[0079] As an efficient physical modification method, microwave has the advantages of fast reaction speed, simple equipment and easy operation. Compared with traditional conduction heating, microwave treatment can significantly change the structure and properties of starch in a short time and improve heating efficiency. Since microwave technology can further enhance the dilution effect of enzymatic hydrolysis on the surface of potato starch particles, more internal amylopectin chains are cleaved and released. As hardness and crystallinity decrease, starch retrogradation is inhibited ( Figure 6 ).

[0080] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase, characterized in that: The specific steps of the method are as follows: S1. Raw material pretreatment: Select fresh potatoes, wash and peel them, cut them into pieces, and immerse them in color-protecting liquid; S2 cooking and cooking: the above potato pieces are cooked and cooked; the cooked potato pieces are removed and drained and placed to cool; S3. Preparation of mashed potatoes: When the potato pieces are cooled to below 30°C, they are made into a uniform puree; S4. Microwave enzymatic hydrolysis: adding a β-amylase preparation to the mashed potatoes, placing the mashed potatoes in a microwave extractor, stirring, and performing microwave treatment and enzymatic hydrolysis; S5. High temperature enzyme inactivation: subjecting the mashed potatoes to high temperature enzyme inactivation treatment; after enzyme inactivation, a finished product of the mashed potatoes is obtained.

2. The method for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase according to claim 1, characterized in that: In step S1, the color protection liquid is ascorbic acid with a mass fraction of 0.05%, and the solvent of the ascorbic acid is water; the immersion time in the color protection liquid is 10 to 20 minutes.

3. The method for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase according to claim 1, characterized in that: In step S4, the temperature program should be set in advance in the microwave extractor, and the temperature program is: ① first control the temperature to 25-34°C, the time to 1 min, and the power to 400W; ② control the temperature to 34-38°C, the time to 1 min, and the power to 400W; ③ control the temperature to 38-42°C, the time to 1 min, and the power to 400W; ④ control the temperature to 42-46°C, the time to 2 min, and the power to 400W; ⑤ control the temperature to 46-48°C, the time to 5 min, and the power to 400W; ⑥ finally control the temperature to 48-50°C, the time to 5-25 min, and the power to 200W.

4. The method for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase according to claim 1, characterized in that: In step S4, the solvent of the β-amylase preparation is water.

5. The method for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase according to claim 1, characterized in that: In step S4, the enzyme activity of the β-amylase preparation is 25 U / g potato mash.

6. The method for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase according to claim 1, characterized in that: In step S4, the pH of the β-amylase preparation is controlled at 6-6.

5.

7. The method for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase according to claim 1, characterized in that: In step S4, the stirring speed is 200-350 rpm and the stirring time is 10-30 min.

8. The method of claim 1 for inhibiting potato mash retrogradation by using microwaves in combination with β-amylase, characterized in that: In step S5, the high temperature enzyme inactivation treatment is: the potato mash is treated at a high temperature of above 100° C. for 10 to 20 minutes to inactivate the enzyme.

9. A mashed potato product, characterized in that: It is prepared by the method according to any one of claims 1 to 8.

10. The mashed potato product according to claim 9, characterized in that: The moisture content of the finished potato mash is 75% to 85%.

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