Method for preventing roast sweet potatoes from spoilage

Abstract

The invention belongs to the technical field of sweet potato processing, and particularly relates to a method for preventing roast sweet potatoes from spoilage, which comprises the following steps: cleaning harvested sweet potatoes, and soaking the cleaned sweet potatoes in a preservative solution for 30-60 minutes; the formula of each liter of the preservative solution is as follows: 2 g to 5 g of calcium beta-hydroxy-beta-methyl butyrate, 0.01 g to 0.03 g of potassium sorbate, 1 g to 2 g of L-methionine and water as a solvent; draining water after soaking, baking until the sweet potatoes are cooked, cooling to room temperature, spraying preservative liquid on the surfaces of the baked sweet potatoes, and drying to obtain the baked sweet potatoes; the spoilage is caused by reproduction of microorganisms, and the microorganisms comprise bacteria and / or fungi; the bacteria are at least one of staphylococcus aureus, bacillus subtilis, pseudomonas, Erwinia and lactic acid bacteria; the fungi are at least one of penicillium, aspergillus and mucor. The method provided by the invention can avoid the generation of microbial drug resistance, and can prevent the roast sweet potatoes from spoilage for a long time.

Description

Technical Field

[0001] This invention belongs to the field of sweet potato processing technology, and specifically relates to a method for preventing roasted sweet potatoes from spoiling and deteriorating. Background Technology

[0002] The main processing techniques for roasted sweet potatoes are as follows: (1) Raw material selection: Select fresh sweet potatoes that are free from disease and pests, rot, and uniform in size; (2) Cleaning: Use mechanical or ultrasonic cleaning to remove surface mud and sand. Some processes retain the outer skin to enhance the flavor, while others peel the skin after cleaning; (3) Cutting / whole potato processing: Determine whether to cut into pieces based on the product form. Cutting into pieces helps to ensure even heating and shorten the roasting time; (4) Baking / roasting: Roast over charcoal or in an oven; (5) Cooling and packaging: Cool to room temperature after roasting. Some products are vacuum-packed or quick-frozen to extend their shelf life.

[0003] The main cause of spoilage in roasted sweet potatoes is microbial contamination. If they are not cooled or packaged promptly after roasting, they are easily contaminated by molds and yeasts in the storage environment, especially in high-temperature and high-humidity environments. Furthermore, some roasted sweet potatoes still have a high moisture content, providing conditions for microbial growth. Even when packaged, poor sealing can allow microorganisms in the environment to affect the sweet potatoes, leading to mold and rancidity. Therefore, inhibiting microbial growth is essential to prevent spoilage of roasted sweet potatoes.

[0004] While some existing technologies exist for preserving roasted sweet potatoes, most rely on inhibiting microbial growth. However, long-term use can lead to microbial resistance, reducing preservation efficiency. Therefore, it is necessary to continue developing new methods to prevent roasted sweet potatoes from spoiling. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preventing roasted sweet potatoes from spoiling and deteriorating.

[0006] The purpose of this invention is to provide a method for preventing roasted sweet potatoes from spoiling, comprising the following steps: After washing the harvested sweet potatoes, soak them in a preservative solution for 30 to 60 minutes. The formula for each liter of preservative solution is as follows: 2 to 5 g of calcium β-hydroxy-β-methylbutyrate, 0.01 to 0.03 g of potassium sorbate, and 1 to 2 g of L-methionine, with water as the solvent. After soaking, drain the water, roast until cooked, cool to room temperature, spray the surface of the roasted sweet potato with preservative liquid, and dry to obtain roasted sweet potato. The spoilage is caused by the proliferation of microorganisms, including bacteria and / or fungi; The bacteria are at least one of Staphylococcus aureus, Bacillus subtilis, Pseudomonas, Erwinia, and lactic acid bacteria; The fungus is at least one of Penicillium, Aspergillus, and Mucor.

[0007] Preferably, in the above method for preventing roasted sweet potatoes from spoiling, the preservative liquid is used to slow down the development of drug resistance in the microorganisms.

[0008] Preferably, in the above method for preventing roasted sweet potatoes from spoiling, the preservative solution has an inhibitory effect on microorganisms that have been passaged up to 30 generations.

[0009] Preferably, in the above method for preventing roasted sweet potatoes from spoiling, the water is drinking water, such as tap water, purified water, or mineral water.

[0010] Preferably, the above method for preventing roasted sweet potatoes from spoiling comprises the following preservative solution per liter: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent. This specific formula exhibits the best antibacterial effect and the longest shelf life.

[0011] Preferably, in the above method for preventing roasted sweet potatoes from spoiling, the preservative liquid is prepared according to the following method: The product is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0012] Preferably, in the above method for preventing roasted sweet potatoes from spoiling, the soaking is performed at room temperature. This method is not demanding in terms of ambient temperature and is easy to implement.

[0013] Preferably, in the above method for preventing roasted sweet potatoes from spoiling, the soaking time is 45 minutes.

[0014] Preferably, in the above method for preventing roasted sweet potatoes from spoiling, the sweet potatoes are washed, peeled, and cut into chunks, and then soaked in a preservative solution. This is to accommodate the needs of different product shapes.

[0015] Preferably, the sweet potatoes do not need to be peeled or cut into pieces, so as to retain the original flavor and taste of the sweet potatoes to the greatest extent.

[0016] Preferably, the roasting temperature used to prevent the roasted sweet potatoes from spoiling is 180℃~220℃, which is a common and optimal roasting temperature.

[0017] Preferably, the dosage of the preservative spray is 0.01 mL per square centimeter of sweet potato surface. This dosage meets the preservation requirements and prevents the roasted sweet potatoes from being contaminated by microorganisms in the environment during storage. This dosage is low, so the moisture content of the roasted sweet potatoes will not change significantly and will not affect the taste of the roasted sweet potatoes.

[0018] Preferably, freezing at -35℃ after spraying the preservative solution can achieve a quick-freezing effect.

[0019] Preferably, the frozen roasted sweet potatoes are stored at -18°C to extend their shelf life.

[0020] Based on the same inventive concept, the present invention also provides a preservative for inhibiting bacteria and / or fungi; wherein the bacteria are at least one of Staphylococcus aureus, Bacillus subtilis, Pseudomonas, Erwinia and lactic acid bacteria; and the fungi are at least one of Penicillium, Aspergillus and Mucor.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention involves washing harvested sweet potatoes and then soaking them in a preservative solution for 30-60 minutes. The preservative solution is formulated as follows per liter: 2-5g of calcium β-hydroxy-β-methylbutyrate, 0.01g-0.03g of potassium sorbate, and 1-2g of L-methionine, with water as the solvent. After soaking, the sweet potatoes are drained, roasted until cooked, cooled to room temperature, and then sprayed with the preservative solution. The sweet potatoes are then dried to obtain roasted sweet potatoes. The spoilage is caused by microbial growth, including bacteria and / or fungi. The bacteria are at least one of Staphylococcus aureus, Bacillus subtilis, Pseudomonas, Erwinia, and Lactobacillus. The fungi are at least one of Penicillium, Aspergillus, and Mucor. The combined use of calcium β-hydroxy-β-methylbutyrate and L-methionine enhances the preservative effect of potassium sorbate, allowing even low doses of potassium sorbate to maintain good preservative activity. The method of this invention can slow down or avoid the development of microbial resistance and can effectively prevent roasted sweet potatoes from spoiling and deteriorating.

[0022] Calcium β-hydroxy-β-methylbutyrate, potassium sorbate, and L-methionine are all permitted raw materials for food processing. For example, in existing technologies, calcium β-hydroxy-β-methylbutyrate can be used in sports nutrition supplements, special medical formula foods, dairy products, cocoa products, and baked goods; potassium sorbate can be used as a preservative in baked goods; and L-methionine is used in baking, coffee, cocoa, beer, and meat products. Preservative treatment before baking kills microorganisms naturally present in sweet potatoes. Combined with high-temperature baking, these microorganisms are further eliminated, significantly reducing the probability of contamination during storage. After soaking and baking, calcium β-hydroxy-β-methylbutyrate, potassium sorbate, and L-methionine remain inside the sweet potato, maintaining a long-lasting antibacterial effect during storage and extending its shelf life.

[0023] In addition, since microorganisms and nutrients such as carbon sources are inevitably present in the natural environment, microorganisms in the environment will multiply using the roasted sweet potatoes as a culture medium when the roasted sweet potatoes are stored, especially at room temperature, which will lead to spoilage during the storage process. Therefore, this invention also includes a post-roasting preservation process to inhibit the proliferation of microorganisms in the environment, reduce the speed and probability of spoilage and deterioration of the roasted sweet potatoes, and extend their shelf life. Detailed Implementation

[0024] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0025] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0026] The inventive concept of this invention is as follows: In order to develop a new method for preventing spoilage of roasted sweet potatoes with broad-spectrum antibacterial activity, this invention provides the following method for preventing spoilage of roasted sweet potatoes: After washing the harvested sweet potatoes, soak them in the preservative solution for 30 to 60 minutes. The formula for each liter of preservative solution is as follows: 2 g to 5 g of calcium β-hydroxy-β-methylbutyrate (HMB-Ca), 0.01 g to 0.03 g of potassium sorbate (Hebei Qianju Biotechnology Co., Ltd., food grade), 1 g to 2 g of L-methionine (Guangzhou Jingfu Bioengineering Co., Ltd., food grade), and water as the solvent.

[0027] After soaking and draining, roast until cooked, cool to room temperature, spray the surface of the roasted sweet potatoes with preservative solution, and dry to obtain roasted sweet potatoes. Preferably, the drying is done by drying the surface moisture of the sweet potatoes at a low temperature such as 45°C; or the drying is done by naturally air drying the surface moisture of the sweet potatoes.

[0028] In the above method, the preservative solution, as a broad-spectrum antibacterial liquid, is used to soak the sweet potatoes before baking. The sweet potatoes absorb the components of the preservative solution, killing any microorganisms they carry. After drying, the sweet potatoes are baked. After baking, the remaining preservative solution components can kill microorganisms in the environment, providing multi-faceted sterilization and achieving a long-lasting anti-corrosion effect, thus extending the shelf life of the baked sweet potatoes. This invention also includes a post-baking preservation process. This step inhibits the proliferation of microorganisms in the environment, reducing the rate and probability of spoilage and extending the shelf life of the baked sweet potatoes.

[0029] The roasted sweet potatoes produced by this invention can be stored at room temperature, maintaining a long shelf life. This reduces the hassle of vacuum packaging, nitrogen filling, and freezing, lowering packaging and storage costs, reducing the use of packaging bags, and is environmentally friendly.

[0030] The effects of the present invention will be illustrated below with reference to specific embodiments, control groups, and experiments.

[0031] Experiment 1: Effect of different preservative formulations on antibacterial activity (1) Refer to Table 1 for formula settings.

[0032] In Table 1, the blank control is sterile tap water without any added substances.

[0033] Examples 1 to 6 are preservative solutions composed of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, and L-methionine, differing only in the specific amounts of the three substances used.

[0034] Control 1 was a mixture of calcium β-hydroxy-β-methylbutyrate and sterile tap water, used to investigate the antibacterial effect of calcium β-hydroxy-β-methylbutyrate as a single factor.

[0035] Control 2 was a mixture of potassium sorbate and sterile tap water, used to explore the antibacterial effect of potassium sorbate as a single factor.

[0036] Control 3 was a mixture of L-methionine and sterile tap water, used to explore the antibacterial effect of L-methionine as a single factor.

[0037] The present invention also includes a control group 4, which is used to explore the synergistic effect of L-methionine with two other components (potassium sorbate and calcium β-hydroxy-β-methylbutyrate).

[0038] Table 1 Different formulations (2) Statistics on antibacterial rate The statistical method for antibacterial rate was based on existing technology. Test strains of various bacteria were prepared: Staphylococcus aureus CMCC(B)26003, Bacillus subtilis CMCC(B)63501, Pseudomonas aeruginosa 21636-HQC, Erwinia lavophila NBRC102418, Lactococcus lactis BNCC359222, Penicillium BNCC117714, and Mucor mitochondritis ATCC26282. Purchased strains were activated once and then prepared at a concentration of 10. 5 A bacterial suspension with a concentration of CFU / mL was prepared, and 1g of preservative solution was added to every 100mL of bacterial suspension. The suspension was allowed to act for 30min. The concentration of viable bacteria before and after the action was statistically analyzed using the live bacteria technique, and the antibacterial rate was calculated.

[0039] Antibacterial rate (%) = 100 * [(Viable bacterial concentration before treatment - Viable bacterial concentration after treatment) / Bacterial concentration before treatment].

[0040] It should be noted that this invention focuses on the antibacterial rate of different preservative formulations, therefore the statistical method for antibacterial rate is only briefly described.

[0041] The statistical results of the antibacterial rate are shown in Tables 2 and 3. The results show that L-methionine alone has almost no antibacterial effect; potassium sorbate alone has a low concentration, so its antibacterial effect is not significant; calcium β-hydroxy-β-methylbutyrate alone has a weak antibacterial effect; and the combined effect of the three is the most significant. In addition, to demonstrate the synergistic antibacterial effect of L-methionine, a control group (4) was also set up. The results showed that the presence of potassium sorbate and calcium β-hydroxy-β-methylbutyrate slightly improved the antibacterial effect compared to single-factor methods, but the addition of L-methionine significantly improved the antibacterial effect. The antibacterial rate data of each embodiment show that the combined use of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, and L-methionine has significant and broad-spectrum antibacterial effects against Staphylococcus aureus, Bacillus subtilis, Pseudomonas, Erwinia, Lactobacillus, Penicillium, Aspergillus, and Mucor.

[0042] Table 2. Statistical results of bacterial inhibition rate Table 3. Statistical results of fungal inhibition rate (3) Drug resistance statistics: The test strains were typical Staphylococcus aureus and Bacillus subtilis. The results are shown in Tables 4 and 5. The results showed that in each control group, for Staphylococcus aureus and Bacillus subtilis, the higher the number of passages, the lower the sensitivity to the preservative solution, and the lower the corresponding antibacterial rate; while the antibacterial stability of each example group was good. It should be noted that in Tables 4 and 5, the reason for activating the strain once before testing was to allow the strain to regain its vitality, which is a routine operation in this field.

[0043] Table 4. Statistical results of Staphylococcus aureus drug resistance. Table 5. Statistical results of drug resistance in Mucor. As can be seen from the data in Tables 4 and 5, the preservative solution of the present invention still has antibacterial effect after 30 generations of propagation, which can reduce or avoid the development of drug resistance.

[0044] The experiments described above selected common microorganisms in the environment, as well as microorganisms that easily cause sweet potatoes to spoil. Studying the antibacterial effect of the preservative solution on these microorganisms provides theoretical guidance for subsequent research on shelf life and the anti-spoilage effect of roasted sweet potatoes in practical applications.

[0045] To investigate the effectiveness of the method of the present invention, the shelf life of roasted sweet potatoes was statistically analyzed, including the following examples and comparisons.

[0046] Example 7 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature for 30 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent.

[0047] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0048] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0049] Example 8 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature for 45 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent.

[0050] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0051] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0052] Example 9 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature for 60 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent.

[0053] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0054] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0055] Compare with 5 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 15 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent.

[0056] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0057] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0058] Compare with 6 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 90 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent.

[0059] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0060] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0061] Compare with 7 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 45 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, with water as the solvent.

[0062] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate and water.

[0063] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0064] Compare with 8 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 45 minutes. The formula for each liter of preservative solution is as follows: 0.01g potassium sorbate, with water as the solvent.

[0065] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of potassium sorbate and water.

[0066] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0067] Compare with 9 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 45 minutes. The formula for each liter of preservative solution is as follows: 1g of L-methionine and water as the solvent.

[0068] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of L-methionine and water.

[0069] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0070] Compare with 10 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 45 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and water as the solvent.

[0071] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, and water.

[0072] After soaking, drain the water and bake at 180℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0073] Compare with 11 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 45 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent.

[0074] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0075] After soaking, drain the water and bake at 220℃ until cooked. Let it cool to room temperature and spray the surface of the baked sweet potato with preservative liquid at a rate of 0.01 mL per square centimeter. Let the surface of the sweet potato air dry naturally to obtain the baked sweet potato.

[0076] Compare with 12 A method to prevent roasted sweet potatoes from spoiling: After washing the harvested sweet potatoes, soak them in a preservative solution at room temperature (25°C) for 45 minutes. The formula for each liter of preservative solution is as follows: 3g of calcium β-hydroxy-β-methylbutyrate, 0.01g of potassium sorbate, and 1g of L-methionine, with water as the solvent.

[0077] The water used is sterilized tap water. The preservative solution is obtained by mixing the prescribed amounts of calcium β-hydroxy-β-methylbutyrate, potassium sorbate, L-methionine, and water.

[0078] After soaking and draining the water, bake at 180℃ until cooked, then let it cool to room temperature to get roasted sweet potatoes.

[0079] Examples 7-9 and Controls 5-6 investigated the effect of different soaking times on the shelf life of roasted sweet potatoes. Example 8 and Controls 7-10 investigated the effect of different preservative formulations on the shelf life of roasted sweet potatoes. Example 8 and Control 11 investigated the effect of different roasting temperatures on the shelf life of roasted sweet potatoes. Example 8 and Control 12 investigated the effect of post-roasting preservation steps on shelf life. See Table 6 for specific differences.

[0080] Table 6. Differences between different methods The results showed that the shelf life (time to spoilage) of roasted sweet potatoes from Examples 7-9 and Controls 5-12, after being placed at room temperature (25°C) and naturally in an indoor environment (without any packaging) at 60% humidity, was 18 days, 19 days, 18 days, 10 days, 12 days, 6 days, 9 days, 4 days, 12 days, 18 days, and 13 days, respectively. This indicates that soaking time, preservative formulation, and the number of preservative treatments have a significant impact on the shelf life of roasted sweet potatoes, while roasting temperature has little effect.

[0081] The criteria for determining whether roasted sweet potatoes have spoiled are any of the following: First, the texture is abnormal, noticeably soft and collapsed; Second, off-odors such as rancid, sour, ammonia, or alcoholic smells are produced; Third, the color turns black or green, or shows signs of browning or mold; Fourth, mold spots appear on the surface or inside.

[0082] It should be noted that, in order to further extend the shelf life of roasted sweet potatoes, roasted sweet potatoes frozen at -35℃ are stored at -18℃. Under this condition, microbial growth is slow and the roasted sweet potatoes are less likely to be infected.

[0083] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the inventive concept of this invention, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0084] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A method for preventing the deterioration of baked sweet potatoes, characterized by, The method comprises the following steps: The harvested sweet potatoes are washed and then soaked in a preservative solution for 30-60 minutes; the formula of the preservative solution is as follows: 2-5 g of calcium β-hydroxy-β-methylbutyrate, 0.01-0.03 g of potassium sorbate, and 1-2 g of L-methionine per liter of water; After soaking, the sweet potatoes are dried, baked, cooled, sprayed with the preservative solution, and dried, thereby obtaining baked sweet potatoes; The spoilage is caused by the reproduction of microorganisms, including bacteria and / or fungi; The bacteria are at least one of Staphylococcus aureus, Bacillus subtilis, Pseudomonas, Erwinia, and Lactobacillus; The fungi are at least one of Penicillium, Aspergillus, and Mucor.

2. The method for preventing the roasting sweet potato from deteriorating according to claim 1, characterized in that, The preservative solution has an antibacterial effect on microorganisms that have been subcultured for 30 generations or less.

3. The method for preventing the roasting sweet potato from deteriorating according to claim 1, characterized in that, The water is drinking water.

4. The method for preventing the roasting sweet potato from deteriorating according to claim 1, characterized in that, The formula of the preservative solution is as follows: 3 g of calcium β-hydroxy-β-methylbutyrate, 0.01 g of potassium sorbate, and 1 g of L-methionine per liter of water.

5. The method for preventing the roasting sweet potato from deteriorating according to claim 1, characterized in that, The soaking is carried out at room temperature.

6. The method for preventing the roasting sweet potato from deteriorating according to claim 5, characterized in that, The soaking time is 45 minutes.

7. The method for preventing the deterioration of the baked sweet potato according to claim 1, characterized by, The baking temperature is 180-220°C.

8. The method for preventing the roasting sweet potato from deteriorating according to claim 7, characterized in that, The spraying dose is 0.01 mL per square centimeter of the surface of the sweet potatoes.

9. A preservative solution characterized in that, The preservative solution is prepared according to the formula of claim 1. The preservative solution is prepared according to the formula of claim 1.

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