A processing method for vacuum low-temperature fried potato balls
By employing a vacuum low-temperature frying process and strictly controlling the composition of potato raw materials, combined with the use of modified starch and leavening agents, the problems of unstable color, insufficient puffing, and high oil content in potato ball processing have been solved, achieving the formation of a hollow structure and improved taste.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING KAIDA HENGYE AGRI TECH DEV
- Filing Date
- 2026-05-29
- Publication Date
- 2026-07-17
Smart Images
Figure CN122397889A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of potato food processing technology, specifically a method for processing vacuum low-temperature fried potato balls. Background Technology
[0002] Potatoes contain starch, protein, dietary fiber, and minerals, making them suitable for processing into snack foods such as French fries, potato chips, and potato balls. Potato balls are mostly made by mixing mashed potatoes with starch, seasonings, and other ingredients, shaping them, and then deep-frying them. The product's structure and taste are affected by the composition of the potato ingredients, the method of mashing the potatoes, the type of starch, the amount of leavening agent used, the moisture content, and the frying conditions.
[0003] In current potato ball processing, the starch and reducing sugar content of potato raw materials lacks targeted control, which easily leads to problems such as darkening of color and insufficient shaping stability during the frying stage. When the degree of softening of potato mash during steaming, particle size during sieving, and cooling temperature are not adequately controlled, the potato mash texture is uneven. After being mixed with starch, water, and leavening agents, it is difficult to form a stable blank, which can easily result in insufficient internal puffing, unstable cavity formation, and a hard texture after frying.
[0004] In addition, some potato ball products are deep-fried at high oil temperatures, making it difficult to coordinate the rate of moisture loss and surface setting, which can easily result in a high oil content on the surface and an uneven internal structure. If the degreasing and cooling processes are not connected with the vacuum frying process, the free oil on the surface can easily enter the pores, affecting the product structure and taste.
[0005] Therefore, this invention proposes a processing method for vacuum low-temperature fried potato balls to overcome the shortcomings of the prior art. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a processing method for vacuum low-temperature fried potato balls, which solves the problems of insufficient control over the composition of potato raw materials, unstable processing of potato puree, and lack of suitable ratio between starch and leavening agent in the existing potato ball processing, which leads to the potato balls easily darkening in color, insufficient internal puffing, unstable formation of hollow structure, and high oil content after frying.
[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for processing vacuum low-temperature fried potato balls, comprising the following steps: Select fresh potatoes with a starch content of 16%–22% and a reducing sugar content of 0.1%–0.29% (dry basis). Wash, peel, and cut into fries or chips with a thickness of 1.5–2.5 cm. Steam or boil French fries or potato chips for 15-25 minutes until the center is completely softened. While still hot, mash them, pass them through a 40-60 mesh sieve, and cool them to 25-35°C to obtain mashed potatoes. Mix 100 parts by weight of mashed potato, 8-20 parts by weight of modified starch, 0.5-1.5 parts by weight of salt, 0.2-0.8 parts by weight of leavening agent, and 5-10 parts by weight of water evenly to obtain a dough-like mixture; the modified starch is acetate starch or cassava modified starch; the leavening agent is a compound leavening agent composed of sodium bicarbonate and glucono-delta-lactone, or ammonium bicarbonate; The dough-like ingredients are shaped into spherical molds and quick-frozen at -18℃ to produce quick-frozen potato balls with a diameter of 2.0 to 3.5 cm. Frozen potato balls are fed into a vacuum low-temperature frying equipment in batches of 25kg. They are fried for 15 to 25 minutes at a vacuum of 0.08 to 0.095 MPa and an oil temperature of 90 to 110°C. After the moisture evaporates and expands, hollow fried potato balls are formed. Hollow fried potato balls were centrifuged and cooled under vacuum conditions at a speed of 200-400 rpm for 5 minutes to obtain de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder, then packaged with nitrogen to obtain vacuum-sealed, low-temperature fried potato balls.
[0008] When the modified starch is acetate starch, the acetate starch content is 8 to 15 parts by weight, and the leavening agent is a compound leavening agent composed of sodium bicarbonate and glucono-delta-lactone, with the compound leavening agent content being 0.3 to 0.8 parts by weight.
[0009] When the modified starch is cassava modified starch, the amount of cassava modified starch is 10 to 20 parts by weight, and the leavening agent is ammonium bicarbonate, which is 0.2 to 0.5 parts by weight.
[0010] The starch and reducing sugar content of the potato raw materials is first limited to reduce the risk of browning and structural collapse during subsequent frying. Steaming, hot mashing, sieving, and temperature-controlled cooling form a uniform gelatinized base material for the potato puree. Modified starch and starch in the potato puree together form a shapeable continuous phase. Salt adjusts the flavor and dough state. Leavening agents release gas during the heating stage, and moisture vaporizes during the vacuum low-temperature frying stage. The gas release and moisture vaporization together promote the formation of internal cavities. The quick-freezing step gives the shaped potato balls a stable shape and heat gradient. Vacuum low-temperature frying lowers the frying temperature, and the water boils and migrates outward, forming cavities inside the balls. Vacuum centrifugation for oil removal and cooling reduce the entry of surface free oil into the pores, maintaining the hollow structure.
[0011] Compared with existing technologies, this invention links potato raw material indicators, cooked and sieved particle size, modified starch, leavening agent, moisture, quick-freezing and shaping, vacuum low-temperature frying and vacuum centrifugal degreasing, so that quick-frozen potato balls can complete puffing, shaping and degreasing at a low oil temperature, and produce vacuum low-temperature fried potato balls with a hollow structure.
[0012] This invention provides a method for processing vacuum low-temperature fried potato balls. It has the following beneficial effects: 1. This invention effectively inhibits the Maillard reaction during processing by strictly limiting the reducing sugar content of fresh potatoes to an extremely low range of 0.1% to 0.29% on a dry basis, and by using a vacuum low-temperature frying process at 0.08 to 0.095 MPa and 90 to 110°C. This reduces the browning degree of the finished product and ensures that the potato balls are golden and uniform in color. At the same time, it avoids the burnt and bitter taste and acrylamide and other byproducts that are easily produced by traditional high-temperature frying.
[0013] 2. This invention combines mashed potato with modified starch and a leavening agent, and then freezes the shaped material at -18°C before directly frying it in a vacuum. The rapid vaporization of internal moisture under vacuum and low pressure, along with the gas-generating effect of the leavening agent, causes the potato balls to expand rapidly and form a hollow structure. At the same time, the added modified starch enhances the strength of the gelatinized network skeleton of the material, providing sufficient structural support and preventing the hollow potato balls from shrinking and collapsing during processing or cooling and degreasing.
[0014] 3. This invention removes oil from the surface and micropores of hollow fried potato balls by centrifugation and cooling at 200-400 rpm under vacuum conditions, effectively removing the oil from the surface and micropores of the potato balls. This reduces the oil content of the final product and improves its crispy texture. Furthermore, the entire process is vacuum-sealed and oxygen-free, and the subsequent nitrogen-filled packaging process reduces the contact between oil and oxygen, slows down the oxidation and rancidity of the oil, and helps extend the shelf life of the product. Attached Figure Description
[0015] Figure 1 The diagram shows the volume percentage of the cavity in different test batches of vacuum low-temperature fried potato balls according to Examples 1 to 6 of the present invention.
[0016] Figure 2 The graphs show the morphological integrity rates of different test batches of vacuum low-temperature fried potato balls from Examples 1 to 6 of the present invention.
[0017] Figure 3 The graphs show the water absorption rates of vacuum low-temperature fried potato balls at different rehydration times in Examples 1 to 6 of this invention.
[0018] Figure 4 The figures show the volume shrinkage rate and collapse distortion rate of different test batches in Example 1 and Comparative Example 1 of the present invention.
[0019] Figure 5 This is a comparison chart of the textural properties of different test batches of Example 1, Comparative Example 2, and Comparative Example 3 of the present invention.
[0020] Figure 6 This is a comparison chart of oil content and acrylamide content in different test batches of Example 1 and Comparative Example 4 of the present invention. Detailed Implementation
[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] Examples 1-6: Example 1: This embodiment provides a method for processing vacuum low-temperature fried potato balls, including the following steps: Select fresh potatoes with a starch content of 19% and a reducing sugar content of 0.15% (dry basis) for washing, peeling, and cutting into French fries or potato chips with a thickness of 2.0cm. Steam the French fries or potato chips for 20 minutes until the center is completely softened, then mash them while hot and pass them through a 50-mesh sieve. Cool to 30°C to obtain mashed potatoes. Mix 100 parts by weight of mashed potato, 11.5 parts by weight of starch acetate, 1.0 part by weight of salt, 0.55 parts by weight of leavening agent (a mixture of sodium bicarbonate and glucono delta-lactone) and 7.5 parts by weight of water evenly to obtain a dough-like mixture. The dough-like ingredients were shaped into spherical molds and quick-frozen at -18℃ to produce quick-frozen potato balls with a diameter of 2.8cm. The frozen potato balls were placed in a vacuum environment of 0.088 MPa and 100°C for 20 minutes in a basket at a rate of 25 kg each. This caused the moisture to evaporate and expand rapidly, resulting in hollow fried potato balls. Hollow fried potato balls were centrifuged and cooled under vacuum at 300 rpm for 5 minutes to remove oil, resulting in de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder and then packaged with nitrogen to obtain vacuum-sealed, low-temperature fried potato balls.
[0023] Example 2: This embodiment provides a method for processing vacuum low-temperature fried potato balls, including the following steps: Select fresh potatoes with a starch content of 22% and a reducing sugar content of 0.29% (dry basis) for washing, peeling and cutting into French fries or potato chips with a thickness of 2.5cm. Steam the French fries or potato chips for 25 minutes until the center is completely softened, then mash them while hot and pass them through a 60-mesh sieve. Cool to 35°C to obtain mashed potatoes. Mix 100 parts by weight of mashed potato, 15 parts by weight of starch acetate, 1.5 parts by weight of salt, 0.8 parts by weight of leavening agent (a mixture of sodium bicarbonate and glucono delta-lactone) and 10 parts by weight of water until a dough-like mixture is obtained. The dough-like ingredients are shaped into spherical molds and quick-frozen at -18℃ to produce quick-frozen potato balls with a diameter of 3.5cm. The quick-frozen potato balls were placed in a vacuum environment of 0.095 MPa and 110°C for 25 minutes in a basket to rapidly vaporize and expand the moisture, resulting in hollow fried potato balls. Hollow fried potato balls were centrifuged and cooled under vacuum at 400 rpm for 5 minutes to remove oil, resulting in de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder and then packaged with nitrogen to obtain vacuum-sealed, low-temperature fried potato balls.
[0024] Example 3: This embodiment provides a method for processing vacuum low-temperature fried potato balls, including the following steps: Select fresh potatoes with a starch content of 16% and a reducing sugar content of 0.1% (dry basis) for washing, peeling, and cutting into fries or chips with a thickness of 1.5cm. Steam the fries or potato chips for 15 minutes until the center is completely softened, then mash them while hot and pass them through a 40-mesh sieve. Cool to 25°C to obtain mashed potatoes. Mix 100 parts by weight of mashed potato, 8 parts by weight of starch acetate, 0.5 parts by weight of salt, 0.3 parts by weight of leavening agent (a mixture of sodium bicarbonate and glucono delta-lactone) and 5 parts by weight of water until a dough-like mixture is obtained. The dough-like ingredients are shaped into spherical molds and quick-frozen at -18℃ to produce quick-frozen potato balls with a diameter of 2.0cm. The quick-frozen potato balls were placed in a vacuum environment of 0.08MPa and 90℃ for 15 minutes in a batch of 25 kg each. This caused the moisture to evaporate and expand rapidly, resulting in hollow fried potato balls. Hollow fried potato balls were centrifuged and cooled under vacuum at 200 rpm for 5 minutes to remove oil, resulting in de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder and then packaged with nitrogen to obtain vacuum-sealed, low-temperature fried potato balls.
[0025] Example 4: This embodiment provides a method for processing vacuum low-temperature fried potato balls, including the following steps: Select fresh potatoes with a starch content of 19% and a reducing sugar content of 0.15% (dry basis) for washing, peeling, and cutting into French fries or potato chips with a thickness of 2.0cm. Steam the French fries or potato chips for 20 minutes until the center is completely softened, then mash them while hot and pass them through a 50-mesh sieve. Cool to 30°C to obtain mashed potatoes. Mix 100 parts by weight of mashed potato, 15 parts by weight of modified cassava starch, 1.0 part by weight of salt, 0.35 parts by weight of leavening agent (ammonium bicarbonate alone) and 7.5 parts by weight of water evenly to obtain a dough-like mixture. The dough-like ingredients were shaped into spherical molds and quick-frozen at -18℃ to produce quick-frozen potato balls with a diameter of 2.8cm. The frozen potato balls were placed in a vacuum environment of 0.088 MPa and 100°C for 20 minutes in a basket at a rate of 25 kg each. This caused the moisture to evaporate and expand rapidly, resulting in hollow fried potato balls. Hollow fried potato balls were centrifuged and cooled under vacuum at 300 rpm for 5 minutes to remove oil, resulting in de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder and then packaged with nitrogen to obtain vacuum-sealed, low-temperature fried potato balls.
[0026] Example 5: This embodiment provides a method for processing vacuum low-temperature fried potato balls, including the following steps: Select fresh potatoes with a starch content of 22% and a reducing sugar content of 0.29% (dry basis) for washing, peeling and cutting into French fries or potato chips with a thickness of 2.5cm. Steam 2.5cm thick fries or chips for 25 minutes until the center is completely softened, then mash them while hot and pass them through a 60-mesh sieve. Cool to 35°C to obtain mashed potatoes. Mix 100 parts by weight of mashed potato, 20 parts by weight of modified cassava starch, 1.5 parts by weight of salt, 0.5 parts by weight of leavening agent (ammonium bicarbonate alone) and 10 parts by weight of water evenly to obtain a dough-like mixture. The dough-like ingredients are shaped into spherical molds and quick-frozen at -18℃ to produce quick-frozen potato balls with a diameter of 3.5cm. The quick-frozen potato balls were placed in a vacuum environment of 0.095 MPa and 110°C for 25 minutes in a basket to rapidly vaporize and expand the moisture, resulting in hollow fried potato balls. Hollow fried potato balls were centrifuged and cooled under vacuum at 400 rpm for 5 minutes to remove oil, resulting in de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder and then packaged with nitrogen to obtain vacuum-sealed, low-temperature fried potato balls.
[0027] Example 6: This embodiment provides a method for processing vacuum low-temperature fried potato balls, including the following steps: Select fresh potatoes with a starch content of 16% and a reducing sugar content of 0.1% (dry basis) for washing, peeling, and cutting into fries or chips with a thickness of 1.5cm. Steam the fries or potato chips for 15 minutes until the center is completely softened, then mash them while hot and pass them through a 40-mesh sieve. Cool to 25°C to obtain mashed potatoes. Mix 100 parts by weight of mashed potato, 10 parts by weight of modified cassava starch, 0.5 parts by weight of salt, 0.2 parts by weight of leavening agent (ammonium bicarbonate alone) and 5 parts by weight of water evenly to obtain a dough-like mixture. The dough-like ingredients are shaped into spherical molds and quick-frozen at -18℃ to produce quick-frozen potato balls with a diameter of 2.0cm. The quick-frozen potato balls were placed in a vacuum environment of 0.08MPa and 90℃ for 15 minutes in a batch of 25 kg each. This caused the moisture to evaporate and expand rapidly, resulting in hollow fried potato balls. Hollow fried potato balls were centrifuged and cooled under vacuum at 200 rpm for 5 minutes to remove oil, resulting in de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder and then packaged with nitrogen to obtain vacuum-sealed, low-temperature fried potato balls.
[0028] The acetate starch and cassava modified starch in Examples 1-6 above are both modified starches.
[0029] Comparative Examples 1-4: Comparative Example 1: Compared with Example 1, the difference is that the quick-freezing step after the dough-like ingredients are formed is omitted. Instead, the dough-like ingredients are formed into potato balls with a diameter of 2.8cm using a spherical mold, and then directly subjected to vacuum low-temperature frying without being quick-frozen at -18℃. All other steps are the same.
[0030] Comparative Example 2: The difference from Example 1 is that no leavening agent (a mixture of sodium bicarbonate and glucono delta-lactone) was added when mixing the dough-like ingredients; otherwise, they are the same.
[0031] Comparative Example 3: Compared with Example 1, the difference is that starch acetate was not added when mixing the ingredients to form a dough-like consistency; otherwise, they are the same.
[0032] Comparative Example 4: Compared with Example 1, the difference is that vacuum low-temperature frying was not used in the frying step. Instead, conventional atmospheric pressure high-temperature frying was used, that is, the frozen potato balls were placed in an environment of atmospheric pressure and oil temperature of 160°C for conventional frying. All other steps are the same.
[0033] Test Examples 1-6: Test Example 1: Vacuum-fried potato balls provided in Examples 1 to 6 were selected as test objects, and five different production batches of products were randomly selected for independent testing for each example. The apparent total volume was measured using the sand displacement method. A graduated cylinder containing standard fine sand was prepared and the initial sand surface volume was recorded. A complete and undamaged vacuum-deep-fried potato ball was buried in the standard fine sand and shaken to make the sand surface level. The total sand surface volume after burying was recorded. The initial sand surface volume was subtracted from the total sand surface volume after burying to obtain the apparent total volume. To measure the true volume of the shell, the vacuum-fried potato balls tested in step 2 were taken out, thoroughly crushed and compacted to expel the gas remaining in the internal space, and the crushed shell fragments were reburied in standard fine sand with a known initial volume. The change in the volume of the sand surface was recorded to obtain the true volume of the shell. To calculate the cavity volume percentage, the cavity volume is obtained by subtracting the actual volume of the shell from the apparent total volume. The cavity volume is then divided by the apparent total volume and multiplied by 100 to obtain the cavity volume percentage data.
[0034] Table 1. Test data on the volume ratio of cavity in different batches of vacuum low-temperature fried potato balls in Examples 1 to 6. ; Figure 1 The horizontal axis represents the test batch, and the vertical axis represents the cavity volume percentage. The data unit is %. The solid line with a square represents Example 1, the dashed line with a square represents Example 2, the solid line with a triangle represents Example 3, the dashed line with a triangle represents Example 4, the solid line with a star represents Example 5, and the dashed line with a star represents Example 6.
[0035] The test results are as follows: Based on the data in Table 1 and Figure 1 As can be seen from the content, the cavity volume ratio of the different production batches of products provided in Examples 1 to 6 fluctuates within the range of 33.7% to 46.1%. During the vacuum low-temperature frying process, the surface of the dough-like ingredients is rapidly thawed upon contact with oil at a temperature of 90°C to 110°C, and a modified starch gelatinization and cross-linking reaction occurs, forming an outer shell with mechanical strength. The internal moisture undergoes a phase change and vaporization upon heating, and combined with the carbon dioxide or ammonia produced by the thermal decomposition of the leavening agent, a gas pressure is generated from the inside out. The outer shell traps the internal gas and expands outwards, forming a hollow state.
[0036] Examples 1 and 4 used intermediate ratios of modified starch and leavening agent, achieving a balance between shell film toughness and internal gas production, maintaining a cavity volume ratio between 43.5% and 46.1%. Examples 2 and 5 used the upper limit ratio; excessive modified starch increased shell thickness and density, limiting outward expansion and resulting in a lower cavity volume ratio compared to Examples 1 and 4. Examples 3 and 6 used the lower limit ratio; the lower modified starch content resulted in insufficient shell support, and reduced leavening agent gas production weakened expansion momentum, reducing the cavity volume ratio to between 33.7% and 37.1%. The fluctuation range of continuous batch data obtained by the sand displacement method is reasonable, and each component can stably form a hollow state within the specified value range, demonstrating the practical operability of the technical solution.
[0037] Test Example 2: Vacuum low-temperature fried potato balls prepared in the equipment in Examples 1 to 6 were selected as test objects. Five independent batches were produced for each example, and the amount of each batch was set to be 25 kg. After each batch of 25 kg of quick-frozen potato balls has been vacuum-fried at low temperature and centrifuged to remove oil and cooled, the oil-removed potato balls are poured out and spread flat on the inspection table. The process involves manual sorting combined with weighing to remove substandard products that have surface collapse, cracks that expose the filling, stick together, or are charred and deformed. The unqualified products are weighed together and the total weight of the unqualified products is recorded. The weight of the intact products is obtained by subtracting the total weight of the unqualified products from 25 kg. The ratio of the weight of the intact products to 25 kg is calculated and multiplied by 100 to obtain the appearance integrity rate data.
[0038] Table 2. Test data on the shape integrity rate of different batches of vacuum low-temperature fried potato balls from Examples 1 to 6. ; Figure 2 The horizontal axis represents the test batch, and the vertical axis represents the appearance integrity rate. The data unit is %. The solid line with a square represents Example 1, the dashed line with a square represents Example 2, the solid line with a triangle represents Example 3, the dashed line with a triangle represents Example 4, the solid line with a star represents Example 5, and the dashed line with a star represents Example 6.
[0039] The test results are as follows: Based on the data in Table 2 and Figure 2According to the content, under the processing conditions of 25 kg per batch, the morphological integrity rate of different batches in Examples 1 to 6 ranged from 90.8% to 98.1%. The dough-like ingredients were formed using a spherical mold and then quick-frozen at -18°C, causing the internal moisture to crystallize and form a hardened frozen layer on the surface. In an environment with a vacuum of 0.08 MPa to 0.095 MPa and an oil temperature of 90°C to 110°C, the frozen layer on the surface of the quick-frozen potato balls thawed upon contact with hot oil, and a starch gelatinization and cross-linking reaction occurred, forming a hard outer shell. The internal ice crystals absorbed heat and vaporized, and combined with the leavening agent, generated gas upon heating, creating internal expansion pressure. The addition of acetate starch and modified cassava starch increased the extensibility and film-forming properties of the dough-like ingredients, giving the hard outer shell tensile strength when subjected to internal gas expansion pressure, reducing the phenomenon of shell cracking and filling leakage.
[0040] In Examples 1 and 4, the shape integrity rate remained between 95.8% and 98.1%. The starch ratio and the gas production of the leavening agent were matched, and the strength of the hard outer shell resisted the tension of gas expansion and mechanical collisions during the frying process. In Examples 2 and 5, the shape integrity rate was between 93.6% and 95.5%. The modified starch addition reached its upper limit, and the increased thickness of the hard outer shell restricted the moisture evaporation channels. The failure of some gas to be discharged in time increased the incidence of local deformation or product adhesion. In Examples 3 and 6, the shape integrity rate fluctuated between 90.8% and 93.5%. The modified starch addition was at its lower limit, and the film toughness of the hard outer shell decreased. Under the action of internal gas scouring and the mechanical force of centrifugal degreasing at 200 rpm, a small number of shells collapsed or broke. The test results verified that the products maintained a high shape integrity rate within the boundaries of different ratios, confirming that the processing method has a basis for engineering application.
[0041] Test Example 3: Vacuum-fried potato balls prepared in Examples 1 to 6 were selected as test subjects, and the initial weight of each test subject was recorded. The vacuum-deep-fried potato balls, after initial weighing, were completely immersed in pure water at 85°C. Soaking times were set to 1 min, 2 min, 3 min, 4 min, and 5 min for the same batch of samples. After the set soaking time is reached, the vacuum low-temperature fried potato balls are taken out of the pure water and placed on the surface of filter paper for 30 seconds to allow the filter paper to absorb the free moisture on the surface of the outer shell. Weigh the vacuum-dehydrated, low-temperature fried potato balls again and record the weight after rehydration. Subtract the initial weight from the rehydrated weight, divide the difference by the initial weight, and multiply by 100 to obtain the water absorption rate data.
[0042] Table 3. Test data on water absorption rate of vacuum low-temperature fried potato balls at different rehydration times in Examples 1 to 6. ; Figure 3 The horizontal axis represents rehydration time in minutes, and the vertical axis represents water absorption rate in percentage. Solid lines with squares represent Example 1, dashed lines with squares represent Example 2, solid lines with triangles represent Example 3, dashed lines with triangles represent Example 4, solid lines with stars represent Example 5, and dashed lines with stars represent Example 6.
[0043] The test results are as follows: Based on the data in Table 3 and Figure 3 As can be seen from the content, the water absorption rate of the vacuum low-temperature fried potato balls provided in Examples 1 to 6 showed an increasing trend within the soaking time range of 1 min to 5 min, and the water absorption rate at 5 min ultimately remained between 182.6% and 226.8%. During the vacuum low-temperature frying step, the phase change and vaporization of water and the thermal decomposition of the leavening agent generate gas, constructing a cavity structure with volumetric space inside the vacuum low-temperature fried potato balls. Under water temperature conditions of 85℃, liquid seeps into the internal cavity through the pore channels distributed in the hard outer shell. The acetate starch and modified cassava starch in the dough-like ingredients hydrate and swell upon contact with hot water. Combined with the water storage capacity of the cavity structure, this increases the overall weight.
[0044] Examples 1 and 4 used intermediate ratios of modified starch and leavening agent. The vacuum-fried potato balls exhibited a high cavity volume ratio and retained intact pores in the outer shell, resulting in low resistance to liquid penetration. Water absorption rates reached 221.5% and 226.8% at 5 minutes, respectively. Examples 2 and 5, with the modified starch addition at its upper limit, increased starch gelatinization and cross-linking led to higher density of the hard outer shell, reduced the number of pore channels, and slowed the rate of water penetration into the internal cavity. Water absorption rates at 5 minutes ranged from 182.6% to 191.2%. Examples 3 and 6, with the modified starch and leavening agent addition at their lower limits, reduced internal gas production resulted in a smaller cavity volume. Although the thinner outer shell facilitated liquid penetration during the initial soaking stage, the limited internal space for liquid containment resulted in a total water absorption rate between 201.3% and 208.4%. Changing the ingredient ratios still maintained the water absorption function, confirming that different ratios could achieve rehydration capabilities.
[0045] Test Example 4: The quick-frozen potato balls prepared in Example 1 and the potato balls formed by spherical molds in Comparative Example 1 but not quick-frozen at -18℃ were selected as test objects. Five independent test batches were prepared for the quick-frozen potato balls prepared in Example 1 and the potato balls formed by spherical molds in Comparative Example 1 but not quick-frozen at -18℃, and the packing amount of each batch was set to 25 kg. The total volume of the test object before it was put into the pot was measured using the sand displacement volume replacement method, and the total volume data before it was put into the pot was recorded. The test subjects were placed in a vacuum environment of 0.088 MPa and 100°C for 20 minutes at a rate of 25 kg per cage. They were then centrifuged and cooled under vacuum conditions at a speed of 300 rpm for 5 minutes to remove oil and obtain the finished product. The total volume of the product leaving the pot was measured using the sand displacement volume replacement method. The total volume before entering the pot was subtracted from the total volume of the product leaving the pot. The difference was then divided by the total volume before entering the pot and multiplied by 100 to obtain the volume shrinkage rate. In each batch of products coming out of the pot, products with a surface depression depth exceeding one-fifth of the sphere diameter are manually sorted out as collapsed and distorted products. The weight of the collapsed and distorted products is recorded, and the weight of the collapsed and distorted products is divided by 25 kg and multiplied by 100 to obtain the collapse and distortion rate.
[0046] Table 4. Test data on volume shrinkage rate and collapse distortion rate of different test batches in Example 1 and Comparative Example 1 ; Figure 4 The horizontal axis represents the test batch, and the vertical axis represents the percentage. The data unit is %. The solid line with squares represents the volume shrinkage rate of Example 1, the dashed line with squares represents the volume shrinkage rate of Comparative Example 1, the solid line with triangles represents the collapse distortion rate of Example 1, and the dashed line with triangles represents the collapse distortion rate of Comparative Example 1.
[0047] The test results are as follows: Based on the data in Table 4 and Figure 4 The results show that in Example 1, the volume shrinkage rate remained between 4.7% and 5.8% across five test batches, and the collapse distortion rate ranged from 1.8% to 2.8%. In Comparative Example 1, the volume shrinkage rate reached 35.7% to 39.2%, and the collapse distortion rate increased to 63.5% to 68.3%. After the dough-like ingredients were quick-frozen at -18°C, the internal free water was converted into solid ice crystals, forming a frozen layer with mechanical strength on the surface of the quick-frozen potato balls. When the quick-frozen potato balls of Example 1 came into contact with 100°C hot oil, the surface frozen layer thawed rapidly and triggered a starch gelatinization and cross-linking reaction, constructing a hard outer shell skeleton capable of supporting internal pressure. The internal ice crystals underwent a phase change under heat conduction and generated outward expansion vapor pressure. Combined with the gas generated by the decomposition of the leavening agent, this gave the hard outer shell skeleton the power to expand outward, offsetting the volume shrinkage stress caused by moisture loss.
[0048] Comparative Example 1 omitted the quick-freezing step. The dough-like ingredients were directly placed into a 0.088 MPa vacuum negative pressure environment at room temperature, causing the boiling point of the water to decrease and rapidly boil and vaporize in all directions. Due to the lack of a surface freezing layer for buffering and a pre-gelatinization and solidification process, the internal moisture of the dough-like ingredients was lost too quickly, and the starch did not have time to form a continuous film-forming network structure. This made the surface unable to resist the destructive tensile force caused by the negative pressure environment and the penetration of internal gas. The gas directly penetrated and escaped from the surface of the unfilmed dough-like ingredients, losing the mechanical forces of inward support and outward expansion. This caused the products from Comparative Example 1 to shrink and collapse after being removed from the fryer, and some products lost structural support and became completely distorted and deformed during the centrifugal degreasing stage. Introducing the quick-freezing step provides a structural maintenance basis for the vacuum low-temperature frying process and solves the processing problem of easy shrinkage and collapse of conventional dough-like ingredients when directly vacuum-fried.
[0049] Test Example 5: Vacuum-fried potato balls prepared in Example 1, Comparative Example 2 and Comparative Example 3 were selected as test objects, and five different production batches of products were sampled for penetration compression tests using a texture analyzer. A cylindrical probe with a diameter of 2 mm was installed on the texture analyzer. The probe descent test speed was set to 1.0 mm / s, the penetration depth was set to 60% of the sample diameter, and the trigger force was set to 0.05 N. A single vacuum-deep-fried potato ball is placed in the center of the texture analyzer test platform. The device is started so that the probe penetrates the sample downwards at a uniform speed. The instrument's built-in software records the relationship between the force and displacement distance of the probe in real time, generating a force-displacement curve. The highest force value occurring during the penetration process was extracted from the force-displacement curve and recorded as the peak fracture force. Simultaneously, the number of times the curve experienced a sudden drop in force accompanied by local peaks during the penetration phase was counted and recorded as the number of fracture peaks. Ten samples were tested repeatedly for each batch, and the arithmetic mean was taken as the data for that batch.
[0050] Table 5. Test data of peak fracture force and number of fracture peaks for different test batches in Example 1, Comparative Example 2 and Comparative Example 3 ; Figure 5 The horizontal axis represents the test batch, and the vertical axis represents the test value. The unit of measurement for peak fracture force is N, and the unit of measurement for the number of fracture peaks is the number of peaks. The solid line with a square represents the peak fracture force of Example 1, the dashed line with a square represents the number of fracture peaks in Example 1, the solid line with a triangle represents the peak fracture force of Comparative Example 2, the dashed line with a triangle represents the number of fracture peaks in Comparative Example 2, the solid line with a star represents the peak fracture force of Comparative Example 3, and the dashed line with a star represents the number of fracture peaks in Comparative Example 3.
[0051] The test results are as follows: Based on the data in Table 5 and Figure 5The results show that in Example 1, the peak fracture force remained between 16.5 N and 19.1 N, and the number of fracture peaks fluctuated between 12 and 16. In Comparative Example 2, the peak fracture force increased to between 49.8 N and 55.1 N, and the number of fracture peaks decreased to between 2 and 4. In Comparative Example 3, the peak fracture force decreased to between 5.8 N and 7.2 N, and the number of fracture peaks was in the range of 1 to 3.
[0052] The dough-like ingredients in Example 1 contain starch acetate and a leavening agent. During the vacuum low-temperature frying step, the leavening agent decomposes upon heating, generating outward-diffusing gas. Simultaneously, the starch acetate absorbs water and undergoes gelatinization and cross-linking upon heating, providing the outer layer structure with extensibility and film-forming properties. The film-forming outer shell prevents gas escape and is expanded by the internal gas pressure, forming a hollow finished product with a porous network wall layer. When the cylindrical probe of the texture analyzer penetrates this network wall layer, the continuous porous framework is destroyed layer by layer, exhibiting continuous and dense brittle fracture peaks on the mechanical curve. Furthermore, due to the hollow internal structure, the required penetration resistance is moderate, giving the product a crisp and chewy texture.
[0053] Comparative Example 2, without any leavening agent, lacked a gas-generating source within its dough-like ingredients. After the moisture phase-change vaporization and release, the starch component solidified and agglomerated under the shrinkage during frying, forming a dense and hard solid structure. The probe needs to overcome significant mechanical resistance to penetrate this dense structure, resulting in an increased peak fracture force. Due to the lack of a brittle porous layer, the structure undergoes overall rigid fracture after yielding under pressure, eliminating the phenomenon of localized continuous fracture and corresponding to a reduced number of fracture peaks. This reflects a high product hardness but a lack of crispness.
[0054] In Comparative Example 3, without added starch acetate, the dough-like ingredients lost their thickening, film-forming, and binding support properties. Although the leavening agent and moisture generated gas upon heating, the gas directly disintegrated the outer structure due to the lack of a flexible film layer. After degreasing and cooling, the outer shell of the product became loose and brittle, immediately crumbling upon probe contact with the sample surface. The low structural load-bearing capacity led to a decrease in the peak fracture force. The powdery structure could not provide multiple penetration resistances, resulting in a flat mechanical curve with few fracture peaks. The comparative data of component variables illustrate the synergistic relationship between the leavening agent and modified starch in forming the specific hollow and crisp texture.
[0055] Test Example 6: The vacuum-fried potato balls prepared in Example 1 and the potato balls fried in Comparative Example 4 at normal pressure and oil temperature of 160°C were selected as test objects. Five independent test batches were prepared for the vacuum-fried potato balls prepared in Example 1 and the potato balls fried in Comparative Example 4 at normal pressure and oil temperature of 160°C. The oil content was determined by Soxhlet extraction. Samples were taken from each test batch and dried to constant weight. The dried samples were ground and pulverized. A quantitative amount of the pulverized sample was weighed and placed in a Soxhlet extractor. Petroleum ether was used as the extraction solvent and refluxed under water bath heating conditions. After extraction, the flask containing the extract was distilled to recover the petroleum ether solvent. The oil remaining in the flask was placed in an oven to dry and weighed. The ratio of the oil weight to the initial weight of the test sample was calculated and multiplied by 100 to obtain the oil content data. Acrylamide content was determined using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS). The test sample was pulverized and homogenized. A quantitative amount of the homogenized sample was weighed and placed in a centrifuge tube. Deionized water and an internal standard were added, and the sample was extracted by shaking. The extract was frozen and centrifuged, and the supernatant was collected. The supernatant was then purified and concentrated using a solid-phase extraction column. The eluent was collected and injected into the HPLC-MS / MS for quantitative analysis. The peak area of acrylamide was extracted from the chromatographic elution curve generated by the instrument software, and the acrylamide content of the test sample was calculated by comparing it with the concentration of the internal standard.
[0056] Table 6. Test data of oil content and acrylamide content in different test batches of Example 1 and Comparative Example 4 ; Figure 6 The horizontal axis represents the test batch, the left vertical axis represents the oil content (%), and the right vertical axis represents the acrylamide content (%). g / kg. The solid line with squares represents the oil content of Example 1, the dashed line with squares represents the oil content of Comparative Example 4, the solid line with triangles represents the acrylamide content of Example 1, and the dashed line with triangles represents the acrylamide content of Comparative Example 4.
[0057] The test results are as follows: Based on the data in Table 6 and Figure 6 From the results, it can be seen that the oil content of Example 1 is between 12.5% and 14.1%, and the acrylamide content is between 21.8%. g / kg up to 28.5 Between g / kg; in Comparative Example 4, the oil content increased to between 34.8% and 38.1%, and the acrylamide content rose to 1180 g / kg. g / kg up to 1410 g / kg range.
[0058] Example 1 involved frying under a vacuum of 0.088 MPa. The reduced pressure lowered the boiling point of the water within the dough-like ingredients, causing rapid boiling and phase change at an oil temperature of 100°C. The pressure released by the outward diffusion of water vapor inhibited the penetration of external frying oil into the pores of the potato balls, reducing oil accumulation within the product. Centrifugal degreasing, utilizing 300 rpm rotational force, removed excess free oil adhering to the outer surface. Potatoes are rich in reducing sugars and asparagine, which readily undergo Maillard reactions and produce acrylamide under high-temperature conditions. In Example 1, the oil temperature was maintained at 100°C, below the critical temperature for the large-scale formation of acrylamide, thus inhibiting the side reaction pathways of amino acids and reducing sugars.
[0059] Comparative Example 4 involved frying under normal pressure. The slower rate of moisture evaporation and the lack of a significant pressure difference to prevent outward steam discharge allowed the frying oil to seep into the potatoes through the capillary pores left by moisture loss. Natural draining was insufficient to remove the surface-adsorbed oil, resulting in a significant increase in the total oil content. At an ambient oil temperature of 160°C, the high heat energy triggered a vigorous Maillard reaction. Asparagine and reducing sugar groups inside the potatoes underwent thermal decarboxylation and other chemical changes at the high-temperature interface, leading to a large accumulation of acrylamide. The test data objectively demonstrate the practical impact of the vacuum low-temperature combined with centrifugal degreasing method on controlling product oil absorption and avoiding the formation of harmful substances during heat processing.
Claims
1. A method for processing vacuum low-temperature fried potato balls, characterized in that, Includes the following steps: Select fresh potatoes, wash them, peel them, and cut them into fries or chips to obtain fries or chips; Steam the fries or chips until the center is completely softened, then mash them while hot, sieve them, and cool them to obtain mashed potatoes. Mix 100 parts by weight of the potato puree, modified starch, salt, leavening agent and water evenly to obtain a dough-like mixture; The dough-like ingredients are shaped into spherical molds and then quick-frozen at -18°C to produce quick-frozen potato balls. The quick-frozen potato balls are placed in an environment with a vacuum degree of 0.08-0.095 MPa and an oil temperature of 90-110°C for 15-25 minutes of vacuum low-temperature frying to rapidly vaporize and expand the moisture, resulting in hollow fried potato balls. The hollow fried potato balls were centrifuged and cooled under vacuum to obtain de-oiled potato balls. The deoiled potato balls are sprayed or rolled with seasoning powder and then packaged with nitrogen to obtain vacuum-sealed low-temperature fried potato balls.
2. The processing method according to claim 1, characterized in that, The fresh potatoes have a starch content of 16-22% and a reducing sugar content of 0.1-0.29% on a dry basis.
3. The processing method according to claim 1, characterized in that, The thickness of the fries or chips is 1.5 to 2.5 cm.
4. The processing method according to claim 1, characterized in that, The cooking time for the French fries or potato chips is 15-25 minutes, the sieve mesh size is 40-60 mesh, and the cooling temperature is 25-35℃.
5. The processing method according to claim 1, characterized in that, The modified starch is 8-20 parts by weight, the salt is 0.5-1.5 parts by weight, the leavening agent is 0.2-0.8 parts by weight, and the water is 5-10 parts by weight.
6. The processing method according to claim 5, characterized in that, The modified starch is acetate starch, and the acetate starch is 8 to 15 parts by weight. The leavening agent is a mixture of sodium bicarbonate and glucono-delta-lactone, and the leavening agent is 0.3 to 0.8 parts by weight.
7. The processing method according to claim 5, characterized in that, The modified starch is cassava modified starch, and the amount of cassava modified starch is 10 to 20 parts by weight. The leavening agent is ammonium bicarbonate alone, and the amount of leavening agent is 0.2 to 0.5 parts by weight.
8. The processing method according to claim 1, characterized in that, The diameter of the quick-frozen potato balls is 2.0 to 3.5 cm.
9. The processing method according to claim 1, characterized in that, The vacuum low-temperature frying process involves a vacuum degree of 0.088 MPa, an oil temperature of 100°C, and a frying time of 20 minutes.
10. The processing method according to claim 1, characterized in that, The centrifugal deoiling process is performed at a speed of 200–400 rpm for 5 minutes.