A sweet potato food product and its preparation method

Abstract

This invention relates to the field of food processing, specifically to a sweet potato food product and its preparation method. The method involves steaming sweet potatoes to a semi-cooked state using a short-time vacuum low-temperature cooking process, followed by the addition of egg yolks to alter the acidity / alkalinity of the sweet potatoes. This provides an environment conducive to the fermentation of high-sugar-tolerant dry yeast while maintaining the product's sensory characteristics. Simultaneously, the enzymes in the sweet potatoes and egg yolks enhance the degradation of macromolecules in the fermentation system, satisfying the nutritional needs of the high-sugar-tolerant dry yeast during fermentation and promoting its reproduction. This, in turn, leads to the production of more carbon dioxide, increasing the puffing degree of the sweet potato food. Compared to existing technologies, this method avoids the excessive addition of food additives, solving the problem of product quality degradation caused by food additives. While ensuring product quality, it achieves the puffing effect of adding chemical compound puffing agents.

Description

Technical Field

[0001] This invention relates to the food industry, specifically to a sweet potato food product and its preparation method. Background Technology

[0002] Sweet potato products are puffed foods made primarily from sweet potatoes through processes such as steaming, cooking, drying, and frying. They are golden and crispy, appealing to consumers, but the products suffer from low puffing levels, which affects their taste.

[0003] To address the aforementioned issues, current technologies generally improve the puffing degree of food by adding food leavening agents. Existing food leavening agents are generally divided into two categories: chemical leavening agents and biological leavening agents. Chemical leavening agents have good puffing effects, but they do not meet the requirements of healthy products. Therefore, current research has largely shifted towards greener and healthier biological leavening agents. The most common biological leavening agent currently is yeast, which achieves puffing through fermentation and gas production. However, on the one hand, yeast has a long puffing time and its puffing effect is not as good as chemical leavening agents. On the other hand, cooked sweet potatoes are alkaline, while yeast thrives in slightly acidic or neutral environments; an alkaline environment will inhibit yeast production or even kill yeast. Therefore, it is not suitable for puffing sweet potato products made from sweet potatoes. Summary of the Invention

[0004] Based on the above problems, the present invention provides a sweet potato food and its preparation method. By steaming sweet potatoes at low temperature and then adding egg yolks and high-sugar-tolerant dry yeast for fermentation, the fermentation efficiency of high-sugar-tolerant dry yeast is improved while maintaining product quality, thereby improving the product puffing degree.

[0005] This invention provides a sweet potato food product and its preparation method, the specific steps of which are as follows:

[0006] S1. Low-temperature steaming pretreatment of sweet potatoes yields material one;

[0007] S2. Add egg yolk and high-sugar-tolerant dry yeast to material one, and ferment at a constant temperature to obtain material two;

[0008] S3. Add glutinous rice flour to material two and dry it a second time to obtain material three;

[0009] S4. Vacuum low-temperature frying process is used to obtain the finished product from the material.

[0010] Furthermore, the low-temperature cooking temperature is 50-55℃, and the time is 6-8 minutes.

[0011] Furthermore, the high-sugar-tolerant dry yeast is activated in warm water at 35°C for 12 minutes before use.

[0012] Furthermore, the addition amount of material one, egg yolk, and high-sugar-tolerant dry yeast is 5:(1-1.2):(0.04-0.06) by mass.

[0013] Furthermore, the constant temperature fermentation temperature is 32-35℃, and the fermentation time is 40-45h.

[0014] Furthermore, the ratio of material two, glutinous rice flour, is 5:(1-1.5) by mass.

[0015] Furthermore, the secondary drying process is carried out until the moisture content of the material is 8%.

[0016] Furthermore, the vacuum low-temperature frying temperature is 90-95℃, and the time is 30-35 minutes.

[0017] Furthermore, the frying process is followed by seasoning and packaging.

[0018] The beneficial effects of this invention are as follows:

[0019] This application involves short-time, low-temperature steaming of sweet potatoes, which cooks the sweet potatoes while partially retaining their enzymes, followed by the addition of egg yolks. On one hand, the addition of egg yolks alters the acidity / alkalinity of the sweet potatoes, providing a suitable environment for yeast growth. On the other hand, the enzymes in the egg yolks synergistically enhance the degradation of large protein and sugar molecules in the sweet potatoes, providing nutrients for yeast fermentation and enabling rapid yeast reproduction. This results in the production of more carbon dioxide gas, thereby increasing the puffing degree of the sweet potato product. Compared with existing technologies, the puffing degree of the sweet potato product prepared in this application can reach 280%-290%.

[0020] This application alters the pH of sweet potato puree by adding acidic food, specifically egg yolk, thus imparting an egg yolk flavor to the sweet potato products. Compared to existing technologies that directly add acid regulators such as citric acid and malic acid, this application achieves a balanced acidity, preventing the product from becoming noticeably sour and enhancing its overall flavor. Detailed Implementation

[0021] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product manual. Instruments used without specified manufacturers are all commercially available conventional products.

[0022] This invention provides a sweet potato food product and its preparation method, the specific steps of which are as follows:

[0023] S1. Low-temperature steaming pretreatment of sweet potatoes yields material one;

[0024] S2. Add egg yolk and high-sugar-tolerant dry yeast to material one, and ferment at a constant temperature to obtain material two;

[0025] S3. Add glutinous rice flour to material two and dry it in two stages to obtain material three;

[0026] S4. Vacuum low-temperature frying process is used to obtain the finished product from the material.

[0027] In this embodiment of the application, the pre-treated sweet potatoes are: selected sweet potatoes that are free of spots, mold, and damage, washed with clean water until no visible mud or sand is left, the skin is removed, and they are cut into 1cm×1cm×1cm pieces and vacuum-packed.

[0028] In this embodiment of the application, the low-temperature cooking temperature is 50-55℃ and the time is 6-8 minutes.

[0029] In this embodiment, the purpose of vacuum-packing the sweet potatoes and then briefly steaming them at a low temperature is to prevent the enzymes in the sweet potatoes from being consumed or inactivated in large quantities during high-temperature, long-term steaming, thus providing enzymes for the subsequent fermentation process. The steaming temperature needs to be 50-55℃, and the time needs to be 6-8 minutes. If the temperature and time are higher than this, most of the enzymes in the sweet potatoes will be destroyed and unable to play a role in the subsequent fermentation process.

[0030] In some specific embodiments, the material after low-temperature steaming is in the form of a paste, namely sweet potato paste. The proportion of material one, egg yolk and high-sugar tolerant dry yeast added by weight is 5:(1-1.2):(0.04-0.06).

[0031] In the embodiments of this application, the high-sugar tolerant dry yeast is a yeast that still has high activity in raw materials with a sugar content of more than 25%. The high-sugar tolerant dry yeast used in this application was purchased from Angel Yeast Co., Ltd.

[0032] In this embodiment, the high-sugar-tolerant dry yeast needs to be activated in 32°C warm water for 12 minutes before use.

[0033] In the embodiments of this application, the fermentation temperature is 32-35℃ and the fermentation time is 4-5h.

[0034] In this embodiment, the addition of acidic egg yolk solves the problem of noticeable sourness in sweet potato products caused by the addition of acid regulators, and imparts an egg yolk flavor to the sweet potato products, ensuring the sensory characteristics of the products. On the other hand, it provides enzymes to the subsequent fermentation system, which, together with the enzymes in the sweet potato, enhances the degradation of macromolecules in the fermentation system, meets the nutritional needs of the high-sugar-tolerant dry yeast during the fermentation process, promotes the reproduction of the high-sugar-tolerant dry yeast, and thus produces more carbon dioxide, improving the puffing degree of the sweet potato products.

[0035] Existing technologies generally involve adding acidity regulators such as citric acid and malic acid to change the acidity or alkalinity of sweet potatoes after high-temperature steaming, thereby obtaining conditions suitable for yeast fermentation. Then, enzyme preparations are added to combine with yeast to promote yeast growth and metabolism, thereby improving the puffing efficiency of the product. However, this method requires the addition of food additives multiple times, and acidity regulators can easily make the product taste noticeably sour, affecting product quality.

[0036] In some specific embodiments, the fermented material 2 is in the form of a paste, namely sweet potato paste, and the ratio of material 2 and glutinous rice flour by weight is 5:(1-1.5).

[0037] In some specific embodiments, in the secondary drying process, the primary drying temperature is 65°C and the drying time is 3-5 hours; the secondary drying temperature is 75°C and the drying time is 4-6 hours.

[0038] In some specific embodiments, the moisture content of the material three that has undergone secondary drying is 8%.

[0039] In some specific embodiments, the vacuum low-temperature frying is carried out using a vacuum low-temperature fryer, with the oil temperature controlled at 90-95℃, the vacuum degree at -0.09 to -0.095 MPa, and the time at 30-35 minutes.

[0040] In some specific embodiments, the vacuum low-temperature frying process is followed by seasoning and packaging.

[0041] Example 1: Preparation of sweet potato food products:

[0042] (1) Select sweet potatoes that are free of spots, mold, and damage, wash them with clean water until there is no visible dirt, remove the skin, cut them into 1cm×1cm×1cm pieces, and vacuum pack them.

[0043] (2) The pretreated sweet potatoes were steamed at 55℃ for 6 minutes and then crushed to obtain material one;

[0044] (3) Add 24 kg of egg yolk and 0.12 kg of high-sugar tolerant dry yeast activated in 32℃ warm water for 12 min to every 100 kg of material one for fermentation. Control the fermentation temperature at 35℃ for 4 hours to obtain material two.

[0045] (4) Add 30kg of glutinous rice flour to material 2 for every 100kg, mix thoroughly, and after maturing and shaping, use a two-stage drying method to dry it. The first drying temperature is 65℃ and the drying time is 5h. The second drying temperature is 75℃ and the drying time is 4h. Dry until the moisture content is 8% to obtain material 3.

[0046] (5) Place the material three in a vacuum fryer and fry for 30 minutes at an oil temperature of 95°C and a vacuum degree of -0.09Mpa to obtain the finished sweet potato food.

[0047] Example 2: Preparation of sweet potato food products:

[0048] (1) Select sweet potatoes that are free of spots, mold, and damage, wash them with clean water until there is no visible dirt, remove the skin, cut them into 1cm×1cm×1cm pieces, and vacuum pack them.

[0049] (2) The pretreated sweet potatoes were steamed at 52℃ for 7 minutes and then crushed to obtain material one;

[0050] (3) Add 22kg of egg yolk and 0.1kg of high-sugar tolerant dry yeast activated in 32℃ warm water for 12min to every 100kg of material one for fermentation. Control the fermentation temperature at 32℃ for 4.5h to obtain material two;

[0051] (4) Add 25kg of glutinous rice flour to material 2 for every 100kg, mix thoroughly, and after maturing and shaping, use a two-stage drying method to dry it. The first drying temperature is 65℃ and the drying time is 4h. The second drying temperature is 75℃ and the drying time is 5h. Dry until the moisture content is 8% to obtain material 3.

[0052] (5) Place the material three in a vacuum fryer and fry for 32 minutes at an oil temperature of 93°C and a vacuum degree of -0.092Mpa. After seasoning, package the finished sweet potato food.

[0053] Example 3: Preparation of sweet potato food products:

[0054] (1) Select sweet potatoes that are free of spots, mold, and damage, wash them with clean water until there is no visible dirt, remove the skin, cut them into 1cm×1cm×1cm pieces, and vacuum pack them.

[0055] (2) The pretreated sweet potatoes were steamed at 50°C for 8 minutes and then crushed to obtain material one;

[0056] (3) Add 20kg of egg yolk and 0.08kg of high-sugar tolerant dry yeast activated in 32℃ warm water for 12min to every 100kg of material one for fermentation. Control the fermentation temperature at 30℃ for 5h to obtain material two.

[0057] (4) Add 20kg of glutinous rice flour to material 2 for every 100kg, mix thoroughly, and after maturing and shaping, use a two-stage drying method to dry. The first drying temperature is 65℃ and the drying time is 3h. The second drying temperature is 75℃ and the drying time is 6h. Dry until the moisture content is 8% to obtain material 3.

[0058] (5) Place the material three in a vacuum fryer and fry for 35 minutes at an oil temperature of 90°C and a vacuum degree of -0.095Mpa. After seasoning, package the finished sweet potato food.

[0059] Comparative Example 1: Preparation of sweet potato food products:

[0060] The method is the same as in Example 1. The difference between Example 1 and Example 2 is that no egg yolk or high-sugar tolerant dry yeast is added in Comparative Example 1.

[0061] Comparative Example 2: Preparation of sweet potato food products

[0062] The method is the same as in Example 1. The difference between Example 2 and Example 1 is that a chemical compound leavening agent is used to replace egg yolk and high-sugar tolerant dry yeast, and is added at a mass ratio of material 1 to chemical compound leavening agent of 1:0.003.

[0063] Comparative Example 3: Preparation of Sweet Potato Foods

[0064] The method is the same as in Example 1. The difference between Example 3 and Example 1 is that the sweet potato was steamed using a high-temperature steaming process. The high-temperature steaming process conditions were 100°C and 6 min.

[0065] Comparative Example 4: Preparation of Sweet Potato Foods

[0066] The method is the same as in Example 1, except that in Comparative Example 4, egg yolks are replaced with citric acid.

[0067] Experimental Example 1: Determination of Expansion

[0068] Expansion degree is an important indicator for measuring the quality of fried products, and it directly affects the texture and taste of fried foods.

[0069] Experimental Method: The degree of expansion is expressed as volumetric expansion rate. The volume of the material is measured using the filling method. A random 20g sample is weighed out before frying and placed in a 1000mL graduated cylinder, filled with millet, and the volume V0 is measured. After vacuum frying, another 20g sample is weighed out and placed in the graduated cylinder, and the volume V1 is measured. The formula for calculating the degree of expansion is as follows:

[0070] Experimental Results: The results of the puffing degree measurement are shown in Table 1. As can be seen from Table 1, the puffing degree of Examples 1-3 is relatively high, all above 280%, indicating that the process of this application can obtain sweet potato food products with high puffing degree. Compared with Comparative Example 1, the puffing degree of Comparative Example 1 is lower than that of Example 1, indicating that the process of this application can significantly improve the puffing degree of sweet potato food. Compared with Comparative Example 2, the puffing degree of Example 1 is not significantly different, indicating that the process of adding biological puffing agent to prepare sweet potato food in this application can achieve the puffing effect of adding chemical puffing agent, and can improve the safety performance of the product while ensuring the puffing degree. Compared with Comparative Examples 3 and 4, the puffing degree of Comparative Examples 3 and 4 is lower than that of Example 1, indicating that the enzymes in sweet potato or egg yolk alone have a slight promoting effect on the puffing effect of high sugar tolerant dry yeast. Only the synergy of the two can have a greater promoting effect on the reproduction of high sugar tolerant dry yeast and significantly improve the puffing degree of sweet potato food.

[0071] Table 1 Results of Expansion Degree Measurement

[0072] .

[0073] Experiment Example 2: Sensory Evaluation

[0074] Sensory evaluation indicators (such as texture, color, flavor, and taste) are important indicators for evaluating the quality of fried products. The quality of sweet potato products can be analyzed through sensory scoring.

[0075] Sensory evaluation method: The sweet potato products obtained in Examples 1-3 and Comparative Examples 1-3 were placed in disposable paper plates and randomly numbered with a 3-digit code. A panel of 10 evaluators (5 males and 5 females, aged 25-45) with food science backgrounds and professional sensory training was selected to evaluate the six products based on four aspects: texture, color, flavor, and mouthfeel. The sensory evaluation panel members scored objectively and independently, with a 3-5 minute interval between evaluations of each sample. Each sample was rinsed with water before evaluation. All scores were tallied, and the average score was taken. Specific scoring criteria are shown in Table 2.

[0076] Table 2 Sensory Evaluation Standards for Sweet Potato Foods

[0077] .

[0078] Experimental Results: Sensory evaluation results are shown in Table 3. As can be seen from Table 3, the sensory scores of Examples 1-3 are quite similar, all above 96 points, indicating that the sweet potato food prepared using the process described in this application has excellent sensory characteristics. Compared with Comparative Example 1, Example 1 has higher scores for all indicators, indicating that the process described in this application can significantly improve the overall quality of the sweet potato food product. Compared with Comparative Example 2, Example 1 has similar scores in texture and color, but in terms of flavor and mouthfeel, Example 1 scores higher than Comparative Example 2, indicating that the addition of chemical leavening agents has a certain impact on the flavor and mouthfeel of sweet potato food products, while the addition of biological leavening agents... The sweet potato food products prepared with the puffing agent have good flavor and texture. Compared with Comparative Examples 3 and 4, the color score of Example 1 is not much different, but the scores of the other three indicators of Example 1 are higher than those of Comparative Examples 3 and 4. This indicates that the enzymes in sweet potato and egg yolk can work together to better promote the growth and metabolism of high-sugar tolerant dry yeast, improve fermentation efficiency, and thus improve the overall quality of the product. The flavor score of Comparative Example 4 is significantly lower than that of Example 1, indicating that the addition of acidity regulators such as citric acid has a greater impact on the flavor of sweet potato food. The addition of egg yolk can not only maintain the flavor of sweet potato, but also give the product an egg yolk flavor, thus improving the overall quality of the product.

[0079] Table 3 Sensory Evaluation Results

[0080] .

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a sweet potato food product, characterized in that, include: S1. Pre-treat sweet potatoes by low-temperature steaming at 50-55℃ for 6-8 minutes to obtain material one, wherein the pre-treated sweet potatoes are in the form of 1cm×1cm×1cm blocks; S2. Add egg yolk and high-sugar-tolerant dry yeast to material one, and ferment at a constant temperature to obtain material two; S3. Add glutinous rice flour to material two and dry it a second time to obtain material three; S4. Vacuum low-temperature frying process is used to obtain the finished product from the material; The addition amount of material one, egg yolk, and high-sugar-tolerant dry yeast is 5:(1-1.2):(0.04-0.06) by mass ratio; The vacuum low-temperature frying temperature is 90-95℃, and the time is 30-35 minutes.

2. The preparation method according to claim 1, characterized in that, The high-sugar-tolerant dry yeast was activated in 35°C warm water for 12 minutes before use.

3. The preparation method according to claim 1, characterized in that, The constant temperature fermentation temperature is 32-35℃, and the fermentation time is 40-45h.

4. The preparation method according to claim 1, characterized in that, The second material, glutinous rice flour, is added in a mass ratio of 5:(1-1.5).

5. The preparation method according to claim 1, characterized in that, The secondary drying process is carried out until the moisture content of the material is 8%.

6. The preparation method according to claim 1, characterized in that, The frying process is followed by seasoning and packaging.

7. A sweet potato food product prepared according to any one of the preparation methods in claims 1-6.