Making method of iced Chinese chestnuts
Through high-temperature treatment of citric acid solution and soaking agents of konjac glucomanan and other components, the problem of browning during the steaming of ice chestnuts is solved, and the effect of maintaining color and nutritional value is achieved.
Patent Information
- Application Number
- CN202510105841.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-04-15
AI Technical Summary
Ice chestnuts are prone to browning during steaming, resulting in a decline in quality, and the prior art is difficult to effectively suppress this phenomenon.
The citric acid solution is used for high-temperature treatment, combined with protective agents such as konjac glucomannan for soaking treatment, inhibiting enzyme activity and oxidation reaction, and reducing the occurrence of Maillard reaction.
Effectively inhibit the browning of chestnuts during steaming, maintain the color and nutritional value of chestnuts, and improve the quality of ice chestnuts.
Smart Images
Figure CN119817780A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of food processing, and in particular to a method for making ice chestnuts. Background Art
[0002] Ice chestnuts are usually made by boiling chestnuts and then freezing them. Ice chestnuts are crisp and tender, sweet, and have a popsicle-like taste, which can give people a refreshing and comfortable feeling. The increased hardness can improve the chewing feeling and satisfaction. Chestnuts themselves are a highly nutritious food. They are rich in carbohydrates, dietary fiber, protein, fat, vitamins and minerals, etc. Frozen chestnuts can well retain these nutrients and extend the shelf life. However, in the production process of ice chestnuts, chestnut kernels are prone to yellowing and blackening, resulting in a decrease in chestnut quality. This is because after the chestnuts are shelled, the phenolic compounds in the chestnut kernels, such as catechol and tannin, come into contact with polyphenol oxidase and peroxidase under the participation of oxygen to form quinone compounds, which lead to the occurrence of browning. In addition, during the steaming process of chestnuts, the carbonyl compounds (reducing sugars) and amino compounds (amino acids and proteins) in the chestnuts are prone to Maillard reaction during processing, and finally produce brown or even black macromolecular substances such as melanin. At the same time, ascorbic acid oxidation also occurs during the processing of chestnuts, which is also a reason for the browning of chestnuts. At present, an appropriate amount of white vinegar can be added during steaming to inhibit its blackening, but its effect is poor and it cannot well control the browning of chestnuts.
[0003] Therefore, the present invention provides a method for making ice chestnuts, which can suppress the problem of chestnuts turning brown during steaming. Summary of the invention
[0004] In view of this, the object of the present invention is to provide a method for making ice chestnuts to solve the problem of browning during the production process of ice chestnuts.
[0005] The present invention solves the above technical problems by the following technical means:
[0006] A method for making ice chestnuts, the method comprising the following steps:
[0007] (1) Selecting mature, plump and fresh chestnuts, washing the chestnuts with clean water, using a shelling machine to scrape off the outer shell and inner skin to obtain shelled chestnuts, heating the citric acid solution to 80-90° C., and then soaking the shelled chestnuts in the heated citric acid solution for 15-20 seconds, and taking them out to obtain pretreated chestnuts;
[0008] (2) placing the pretreated chestnuts into a protective agent for soaking, that is, taking out the chestnuts after they are fully coated with the protective agent to obtain treated chestnuts;
[0009] (3) transferring the treated chestnuts into a pot, steaming them for 10-15 min at a temperature of 100-120° C. and a steam pressure of 0.05-0.1 MPa to obtain steamed chestnuts, and then cooling the steamed chestnuts in ice water at 0-5° C. to obtain cooled chestnuts;
[0010] (4) The cooled chestnuts are transferred into a quick freezer and quick-frozen at -25 to -30°C for 30 to 40 minutes. The chestnuts are taken out and bagged and sealed to obtain frozen chestnuts, which are then placed at -18 to -20°C for frozen storage.
[0011] Chestnuts are prone to Maillard reaction at high temperatures, and the Maillard reaction will become more severe as the steaming time increases, so long-term high-temperature treatment should be avoided. High-pressure steaming can speed up the ripening process of chestnut kernels, shorten the steaming time, and thus reduce the occurrence of Maillard reaction.
[0012] Furthermore, the concentration of the citric acid solution in step (1) is 4-5wt%.
[0013] After the chestnuts are shelled, the phenolic compounds in the chestnut kernels are easily exposed to polyphenol oxidase and peroxidase with the participation of oxygen, resulting in browning reaction, which causes the chestnuts to turn black. Therefore, the chestnut kernels are treated in a citric acid solution at 80-90°C. Citric acid can effectively inhibit the activity of enzymes, and the activity of enzymes continues to decrease under high temperature treatment. Therefore, citric acid solution is used in conjunction with high temperature treatment to reduce the activity of polyphenol oxidase and peroxidase in chestnuts and inhibit the occurrence of browning reaction.
[0014] Furthermore, in step (3), the chestnuts are cooled to 10-15°C.
[0015] The chestnuts are cooled in ice water. The main component of the protective agent is konjac glucomannan. The konjac glucomannan sol will gradually turn into a liquid at a certain temperature. Therefore, when the protective agent on the surface of the chestnut is cooled to 10-15°C, the protective agent will gradually turn into a liquid and fall off the surface of the chestnut, so as to achieve the purpose of removing the protective agent on the surface of the chestnut. At the same time, when the chestnuts are cooled and then quickly frozen, the ice crystals generated during the quick freezing process can be reduced, and the taste and nutritional value of the chestnuts can be better maintained.
[0016] Furthermore, the protective agent comprises the following raw materials: konjac glucomannan, sophorolipids, sorbitol and activated carbon.
[0017] Furthermore, the ratio of each raw material of the protective agent is as follows: the weight ratio of konjac glucomannan, sophorolipid, sorbitol and activated carbon is (3-4): (2-2.5): (1.2-1.5): (1.5-2).
[0018] Further, the protective agent preparation method is as follows:
[0019] Sophorolipids are added to water, stirred at a rate of 300-350 r / min for 5-10 min to obtain a sophorolipid solution, and then sorbitol and activated carbon are added to the sophorolipid solution, stirred evenly, and then konjac glucomannan is added, and mixed evenly to obtain a protective agent.
[0020] Furthermore, the particle size of the activated carbon is 0.5-0.6 mm.
[0021] The chestnut is soaked in a protective agent, that is, the surface of the chestnut is covered with the protective agent, and the chestnut is put into a steamer for steaming. As the heating proceeds, the protective agent in the sol state on the surface of the chestnut gradually changes into a gel state, and the chestnut is sealed in the protective agent in the gel state, thereby hindering the contact of the chestnut with oxygen, avoiding the oxidation of ascorbic acid, reducing the occurrence of browning reaction, and preventing the discoloration of the chestnut. At the same time, sorbitol is also added to the protective agent, and the konjac glucomannan in the protective agent acts through hydrogen bonds, which improves the interaction between the konjac glucomannan molecules, thereby improving the tightness of the protective agent, and further inhibiting the entry of oxygen to prevent oxidation. Polyphenol oxidase is the main cause of enzymatic browning, and polyphenol oxidase is a copper ion metal enzyme, wherein copper ion is an important component of the active center of polyphenol oxidase, responsible for catalyzing the oxidation reaction of polyphenol substrates, so sophorolipids are added to the protective agent, which can inhibit the copper ions in polyphenol oxidase and then inhibit the activity of polyphenol oxidase, thereby reducing the occurrence of browning reaction. In addition, the surface of the pretreated chestnut contains citric acid, which forms an acidic environment on the surface of the chestnut, which is not conducive to the occurrence of the Maillard reaction and further inhibits the browning of the chestnut. In addition, a certain amount of activated carbon is added to the protective agent to quickly absorb heat and transfer it to the chestnut, increase the rate of chestnut ripening, shorten the high-temperature steaming time, and thus reduce the occurrence of the Maillard reaction. After steaming, the chestnut is cooled, and the protective agent on the surface of the chestnut gradually becomes liquid, and then falls off from the surface of the chestnut to obtain the prepared chestnut.
[0022] Beneficial effects:
[0023] The present invention uses the prepared protective agent to perform color protection treatment before steaming chestnuts, which can effectively inhibit the chestnuts from turning black during the steaming process, and can maintain the color of the chestnuts. The prepared ice chestnuts have high nutritional value and good taste. At the same time, the added protective agent is also prepared by non-toxic and harmless products, and will not affect the quality of the chestnuts. Therefore, the ice chestnut products obtained by the treatment of the present invention are of higher quality and are more popular among the general public. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 : Finished picture of ice chestnuts. DETAILED DESCRIPTION
[0025] The present invention will be described in detail below with reference to specific embodiments:
[0026] Embodiment 1:
[0027] Preparation of protective agent:
[0028] 2 g of sophorolipid was added to 150 g of water, stirred at 300 r / min for 5 min to obtain a sophorolipid solution, and then 1.2 g of sorbitol and 1.5 g of activated carbon with a particle size of about 0.5 mm were added to the sophorolipid solution, stirred evenly, and then 3 g of konjac glucomannan was added and mixed evenly to obtain a protective agent.
[0029] Preparation of ice chestnuts:
[0030] (1) Selecting mature, plump and fresh chestnuts, washing the chestnuts with clean water, using a shelling machine to scrape off the outer shell and inner skin to obtain shelled chestnuts, heating a 4wt% citric acid solution to 80°C, and then soaking the shelled chestnuts in the heated 4wt% citric acid solution for 15s, and taking out the chestnuts to obtain pretreated chestnuts;
[0031] (2) placing the pretreated chestnuts into a protective agent for soaking, that is, taking out the chestnuts after they are fully coated with the protective agent to obtain treated chestnuts;
[0032] (3) moving the treated chestnuts into a pot, steaming them for 10 min at a temperature of 100° C. and a steam pressure of 0.05 MPa to obtain steamed chestnuts, and then cooling the steamed chestnuts in ice water at 0° C. to 10° C. to obtain cooled chestnuts;
[0033] (4) The cooled chestnuts are transferred into a quick freezer and quick-frozen at -25°C for 30 minutes. The chestnuts are taken out and bagged and sealed to obtain frozen chestnuts, which are then placed at -18°C for frozen storage.
[0034] Embodiment 2:
[0035] Preparation of protective agent:
[0036] 2.25 g of sophorolipid was added to 190 g of water, stirred at 330 r / min for 8 min to obtain a sophorolipid solution, and then 1.35 g of sorbitol and 1.75 g of activated carbon with a particle size of about 0.55 mm were added to the sophorolipid solution, stirred evenly, and then 3.5 g of konjac glucomannan was added and mixed evenly to obtain a protective agent.
[0037] Preparation of ice chestnuts:
[0038] (1) Selecting mature, plump and fresh chestnuts, washing the chestnuts with clean water, using a shelling machine to scrape off the outer shell and inner skin to obtain shelled chestnuts, heating a 4wt% citric acid solution to 85°C, and then soaking the shelled chestnuts in the heated 4wt% citric acid solution for 18s, and taking out the pretreated chestnuts;
[0039] (2) placing the pretreated chestnuts into a protective agent for soaking, that is, taking out the chestnuts after they are fully coated with the protective agent to obtain treated chestnuts;
[0040] (3) moving the treated chestnuts into a pot, steaming them for 12 min at a temperature of 120° C. and a steam pressure of 0.08 MPa to obtain steamed chestnuts, and then cooling the steamed chestnuts in 2° C. ice water to 12° C. to obtain cooled chestnuts;
[0041] (4) The cooled chestnuts are transferred into a quick freezer and quick-frozen at -28°C for 35 minutes. The chestnuts are taken out and bagged and sealed to obtain frozen chestnuts, which are then placed at -19°C for frozen storage.
[0042] Embodiment 3:
[0043] Preparation of protective agent:
[0044] 2.5 g of sophorolipid was added to 240 g of water, stirred at 350 r / min for 10 min to obtain a sophorolipid solution, and then 1.5 g of sorbitol and 2 g of activated carbon with a particle size of about 0.6 mm were added to the sophorolipid solution, stirred evenly, and then 4 g of konjac glucomannan was added and mixed evenly to obtain a protective agent.
[0045] Preparation of ice chestnuts:
[0046] (1) Selecting mature, plump and fresh chestnuts, washing the chestnuts with clean water, using a shelling machine to scrape off the outer shell and inner skin to obtain shelled chestnuts, heating a 5wt% citric acid solution to 90°C, and then soaking the shelled chestnuts in the heated 5wt% citric acid solution for 20s, and taking out the chestnuts to obtain pretreated chestnuts;
[0047] (2) placing the pretreated chestnuts into a protective agent for soaking, that is, taking out the chestnuts after they are fully coated with the protective agent to obtain treated chestnuts;
[0048] (3) moving the treated chestnuts into a pot, steaming them for 15 min at a temperature of 120° C. and a steam pressure of 0.1 MPa to obtain steamed chestnuts, and then cooling the steamed chestnuts in 5° C. ice water to 15° C. to obtain cooled chestnuts;
[0049] (4) The cooled chestnuts are transferred into a quick freezer and quick-frozen at -30°C for 40 minutes. The chestnuts are taken out and bagged and sealed to obtain frozen chestnuts, which are then placed at -20°C for frozen storage.
[0050] Comparative Example 1:
[0051] This comparative example is in contrast to Example 1, the only difference being that the raw materials of the protective agent are different, specifically, no sophorolipid is added, and the specific method is as follows:
[0052] 1.2 g of sorbitol was added to 150 g of water, and the mixture was stirred at 300 r / min for 5 min to obtain a sorbitol solution. Then, 1.5 g of activated carbon with a particle size of about 0.5 mm was added to the sophorolipid solution, and 3 g of konjac glucomannan was added after stirring evenly, and the mixture was mixed evenly to obtain a protective agent.
[0053] The preparation method of ice chestnuts in this comparative example is the same as that in Example 1.
[0054] Comparative Example 2:
[0055] This comparative example is in contrast to Example 1, the only difference being that the raw materials of the protective agent are different, specifically, sorbitol is not added, and the specific method is as follows:
[0056] 2 g of sophorolipid was added to 150 g of water, and the mixture was stirred at 300 r / min for 5 min to obtain a sophorolipid solution. Then, 1.5 g of activated carbon with a particle size of about 0.5 mm was added to the sophorolipid solution, and 3 g of konjac glucomannan was added after stirring, and the mixture was mixed evenly to obtain a protective agent.
[0057] The preparation method of ice chestnuts in this comparative example is the same as that in Example 1.
[0058] Comparative Example 3:
[0059] This comparative example is in contrast to Example 1, the only difference being that the raw materials of the protective agent are different, specifically, no activated carbon is added, and the specific method is as follows:
[0060] 2 g of sophorolipid was added to 150 g of water, and the mixture was stirred at 300 r / min for 5 min to obtain a sophorolipid solution. Then 1.2 g of sorbitol was added to the sophorolipid solution, and after stirring evenly, 3 g of konjac glucomannan was added and mixed evenly to obtain a protective agent.
[0061] The preparation method of ice chestnuts in this comparative example is the same as that in Example 1.
[0062] experiment:
[0063] There were 8 groups in total in this experiment. Each group selected 100 shelled, intact, and undamaged chestnuts weighing 20±1g for the ice chestnut production experiment, with three replicates. The specific ice chestnut experimental process is as follows:
[0064] 1. Preparation method:
[0065] (1) Selecting mature, plump and fresh chestnuts, washing the chestnuts with clean water, using a shelling machine to scrape off the outer shell and inner skin to obtain shelled chestnuts, heating a 4wt% citric acid solution to 80°C, and then soaking the shelled chestnuts in the heated 4wt% citric acid solution for 15s, and taking out the chestnuts to obtain pretreated chestnuts;
[0066] (2) placing the pretreated chestnuts into a protective agent for soaking, that is, taking out the chestnuts after they are fully coated with the protective agent to obtain treated chestnuts;
[0067] (3) moving the treated chestnuts into a pot, steaming them for 10 min at a temperature of 100° C. and a steam pressure of 0.05 MPa to obtain steamed chestnuts, and then cooling the steamed chestnuts in ice water at 0° C. to 10° C. to obtain cooled chestnuts;
[0068] (4) The cooled chestnuts are transferred into a quick freezer and quick-frozen at -25°C for 30 minutes. The chestnuts are taken out and bagged and sealed to obtain frozen chestnuts, which are then placed at -18°C for frozen storage.
[0069] Experimental group 1: referring to the above preparation method, and using the treatment agent prepared in Example 1;
[0070] Comparative groups 1-3: referring to the above preparation method, the treatment agents prepared in Comparative Examples 1-3 were used respectively;
[0071] Comparative group 4: Referring to the above preparation method, in step (1), 80°C hot water was used instead of 80°C citric acid solution to heat treat the chestnuts, and in step (2), the treatment agent prepared in Example 1 was used;
[0072] Comparative group 5: referring to the above preparation method, no citric acid solution was used for pretreatment in step (1), and the treatment agent prepared in Example 1 was used in step (2);
[0073] Comparative group 6: referring to the above preparation method, no protective agent was used in step (2);
[0074] Comparative Group 7: Referring to the above preparation method, no citric acid solution was used for pretreatment in step (1), and no protective agent was used in step (2).
[0075] According to the above method, the steamed chestnuts were cooled and subjected to sensory evaluation. The sensory evaluation standards are shown in Table 1. 100 chestnuts were randomly selected from each experimental group to observe their degree, and the results were averaged. The results are shown in Table 2.
[0076] Table 1 Sensory evaluation standards
[0077] Appearance luster Browning degree Overall darkening, severe browning No light, dark 5 Most of them are dark and brown Average brightness, no bright luster 4 Some parts slightly faded brown High brightness, no bright luster 3 Slightly faded in some areas Bright, slightly less shiny than the original 2 Overall golden or yellow Bright, keep original luster 1
[0078] Table 2 Experimental results
[0079]
[0080]
[0081] Analyzing Tables 1 and 2, we can get:
[0082] 1. Comparative Examples 1-3 are compared with the embodiments, and the only difference is the difference in the raw materials of the protective agent. Compared with Group 1, the browning degree of chestnuts after cooking is higher than that without adding sophorolipids. This is because sophorolipids can compete with polyphenol oxidase in chestnuts for copper ions, thereby inhibiting the activity of polyphenol oxidase and reducing the occurrence of browning reaction. Comparative Group 2 does not add sorbitol, and the browning degree of chestnuts is higher, which is grayish yellow. This is because sorbitol can increase the cross-linking degree of konjac glucomannan, thereby increasing the compactness of the protective agent after curing, preventing the entry of oxygen, reducing the oxidation of ascorbic acid, and thus reducing the degree of browning of chestnuts. Therefore, the browning degree of Comparative Group 2 is higher. Comparative Group 3 does not add activated carbon, and the heat conduction is slow, resulting in a longer time required for steaming chestnuts, resulting in a more serious Maillard reaction during this period, resulting in a higher degree of browning of chestnuts in Comparative Example 3.
[0083] 2. Compared with experimental group 1, control group 4 used 80°C hot water instead of citric acid for pretreatment. Hot water can significantly reduce the activity of polyphenol oxidase, thereby inhibiting the browning of chestnuts. However, citric acid can not only improve the inhibitory effect of pretreatment on the activity of polyphenol oxidase, but also form an acidic environment on the surface of chestnuts, inhibiting the occurrence of Maillard reaction during the steaming process of chestnuts. Therefore, the browning of control group 4 is more serious than that of experimental group 1.
[0084] 3. Compared with experimental group 1, control group 5 was not pretreated. During the processing, the phenolic substances in the chestnut contacted with polyphenol oxidase and browning reaction occurred. However, with the increase of temperature, the activity of the enzyme will gradually decrease, and the protective agent can hinder the contact between chestnut and oxygen, and the sophorolipids therein can also reduce the activity of the enzyme, so the browning of control group 5 is not too serious. Compared with experimental group 1, control group 6 was not treated with a protective agent. The oxidation of ascorbic acid and polyphenols in the chestnut during processing caused the chestnut to brown, and the long heating time caused the Maillard reaction to be serious, so the browning degree of control group 7 was higher. Control group 7 was not pretreated, nor was it treated with a protective agent. The chestnut was severely browned, the whole was dark, the browning degree was high, and the browning degree reached 4.32, and the quality of the chestnut was seriously reduced. Therefore, it is explained that Example 1 can reduce the browning of chestnuts during steaming and maintain the quality of chestnuts.
[0085] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention. The techniques, shapes, and structural parts not described in detail in the present invention are all known technologies.
Claims
1. A method for making ice chestnuts, characterized in that: The method comprises the following steps: (1) washing and shelling chestnuts to obtain shelled chestnuts, and then treating the shelled chestnuts in a citric acid solution at 80 to 90° C. for 15 to 20 seconds to obtain pretreated chestnuts; (2) placing the pretreated chestnuts into a protective agent for soaking, that is, taking out the chestnuts after they are fully coated with the protective agent to obtain treated chestnuts; (3) steaming the processed chestnuts at a temperature of 100 to 120° C. and a steam pressure of 0.05 to 0.1 MPa for 10 to 15 minutes until the chestnuts are cooked, and then cooling them in ice water at 0 to 5° C. to obtain prepared chestnuts; (4) Quickly freeze the prepared chestnuts at a temperature of -25 to -30°C for 30 to 40 minutes to obtain ice chestnuts, which are then frozen and stored at -18 to -20°C.
2. The method for making ice chestnuts according to claim 1, characterized in that: The concentration of the citric acid solution in step (1) is 4-5 wt %.
3. The method for making ice chestnuts according to claim 2, characterized in that: In the step (3), the chestnuts are cooled to 10-15°C.
4. The method for making ice chestnuts according to claim 3, characterized in that: The protective agent comprises the following raw materials: konjac glucomannan, sophorolipid, sorbitol and activated carbon.
5. The method for making ice chestnuts according to claim 4, characterized in that: The ratio of each raw material of the protective agent is as follows: the weight ratio of konjac glucomannan, sophorolipid, sorbitol and activated carbon is (3-4): (2-2.5): (1.2-1.5): (1.5-2).
6. The method for making ice chestnuts according to claim 5, characterized in that: The protective agent preparation method is as follows: Sophorolipids are added to water, stirred at a rate of 300-350 r / min for 5-10 min to obtain a sophorolipid solution, and then sorbitol and activated carbon are added to the sophorolipid solution, stirred evenly, and then konjac glucomannan is added, and mixed evenly to obtain a protective agent.
7. The method for making ice chestnuts according to claim 6, characterized in that: The particle size of the activated carbon is 0.5-0.6 mm.