Method for processing fresh chinese yam into yam vermicelli

Abstract

The application discloses a method for processing sweet potato vermicelli by using fresh sweet potatoes, and comprises the following steps: (1) peeling fresh sweet potatoes, washing and cutting the sweet potatoes, and then grinding the sweet potatoes to obtain sweet potato pulp; (2) heating the sweet potato pulp obtained in the step (1) to 45-50 DEG C, and stirring and keeping warm for a period of time to obtain heat-treated sweet potato pulp; (3) soaking rice in water, and then grinding the rice to obtain rice pulp; (4) respectively performing pressure filtration and dehydration treatment on the heat-treated sweet potato pulp obtained in the step (2) and the rice pulp obtained in the step (3) to obtain rice wet powder and sweet potato wet powder; and (5) uniformly mixing the rice wet powder and the sweet potato wet powder obtained in the step (4) according to a proportion, and then placing the mixture in a rice powder machine to mature, extruding vermicelli, and cutting to obtain sweet potato vermicelli.

Description

Technical Field

[0001] This invention belongs to the field of food processing, specifically relating to a method for processing yam rice vermicelli using fresh yam. Background Technology

[0002] Chinese yam, also known as yam, is the underground tuber of a herbaceous plant in the Dioscoreaceae family. It has been cultivated in my country for hundreds of years and is widely distributed in North and Central China. As a plant used for both food and medicine, Chinese yam possesses high medicinal value in addition to its common food uses. According to the *Compendium of Materia Medica*, Chinese yam has the effects of "benefiting kidney qi, strengthening the spleen and stomach, stopping diarrhea and dysentery, resolving phlegm, and moisturizing the skin and hair." Modern pharmacological studies have shown that Chinese yam contains various bioactive components, such as polysaccharides, saponins, allantoin, and choline, which have functions such as lowering blood sugar and blood lipids, anti-oxidation, anti-tumor, anti-aging, and immune regulation. Therefore, Chinese yam is an excellent raw material for food processing.

[0003] Vermicelli, originating in southern China and dating back to the Qin Dynasty, is a popular food enjoyed by consumers both domestically and internationally. It boasts a large market in China and Southeast Asia, and also has significant markets in Europe, the United States, and Canada, regions with large Chinese communities. The raw materials for vermicelli processing are primarily agricultural products with high starch content, such as rice starch, sweet potato starch, pea starch, and mung bean starch. Chinese yam, rich in starch, is an excellent raw material for vermicelli processing. Developing Chinese yam vermicelli is not only feasible but also addresses the limitations of traditional vermicelli varieties, enhancing its health benefits and providing consumers with more choices. However, Chinese yam vermicelli is currently relatively rare in the market, indicating a promising market prospect for its processing.

[0004] Currently, when producing yam vermicelli, manufacturers mix yam powder with rice and other raw materials, then extrude it through gelatinization. The yam powder is made from fresh yam through processes such as color protection, high-temperature drying, and pulverization. Existing technology for producing yam vermicelli using yam powder increases product safety risks due to the color protection process required. Furthermore, the high-temperature drying step necessitates additional investment in high-temperature drying equipment and significant energy consumption, substantially increasing costs. If fresh yam is used directly for processing, the heating process causes enzymatic and non-enzymatic browning (Maillard browning) of the yam components, resulting in vermicelli with an undesirable color. This is because fresh yam contains highly active enzymes such as polyphenol oxidase, peroxidase, and phenylalanine ammonia-lyase, which use phenolic active substances like chlorogenic acid as substrates, making them prone to enzymatic browning during heating. Furthermore, because Chinese yam contains a large amount of protein, free amino acids, and reducing sugars, these proteins and free amino acids easily condense with reducing sugars during heating, resulting in Maillard browning and a dark color. In the processing of Chinese yam vermicelli, the raw material undergoes pre-cooking and gelatinization, extrusion, further cooking, and drying, with heating times exceeding 60 minutes. Therefore, browning of the Chinese yam components is unavoidable, thus affecting the color of the vermicelli. For easily browned raw materials like fresh Chinese yam, a better solution is to avoid prolonged high-temperature processing. However, this method is clearly unsuitable for processing Chinese yam vermicelli. Summary of the Invention

[0005] The purpose of this invention is to provide a method for processing yam vermicelli using fresh yam, which solves the problem of poor color of yam vermicelli produced by existing technology, and reduces the breakage rate and cooking loss rate of yam vermicelli.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for processing fresh yam into yam vermicelli includes the following steps:

[0008] (1) Peel and wash fresh yam, cut it into sections, then add water and grind it into a paste to obtain yam paste;

[0009] (2) Heat the yam pulp obtained in step (1) to 45~50℃, stir and keep warm for a period of time to obtain heat-treated yam pulp;

[0010] (3) Soak the rice in water, then grind it into a paste to obtain rice paste;

[0011] (4) The heat-treated yam pulp obtained in step (2) and the rice pulp obtained in step (3) are subjected to pressure filtration and dehydration treatment to obtain wet rice powder and wet yam powder.

[0012] (5) Mix the rice flour and yam flour obtained in step (4) in an appropriate ratio, then cook them in a rice noodle machine, extrude the noodles, and cut them to obtain the yam noodles.

[0013] Based on the principle that yam starch is insoluble in water below 50℃ and its gelatinization temperature is between 55℃ and 80℃, and that the solubility of phenolic substances, free amino acids, and reducing sugars, which cause high-temperature browning of yam, increases with increasing temperature in water, this invention dissolves phenolic substances, free amino acids, and reducing sugars in water as much as possible by grinding fresh yam into a paste and heating it to 45-50℃. Then, pressure filtration and dehydration are performed to remove these substances while retaining the yam starch, effectively reducing the browning degree of the resulting yam vermicelli. Furthermore, this invention processes fresh yam and rice into wet yam vermicelli and wet rice vermicelli, respectively, resulting in lower starch breakage and better preservation of starch gel properties compared to dry vermicelli. In addition, water-soluble proteins, amino acids, cellulose, minerals, vitamins, and other substances in yam and rice that affect vermicelli gel formation are removed during dehydration, thus reducing the breakage rate and cooking loss rate of the yam vermicelli and improving its quality.

[0014] In step (2), the yam pulp is preferably heated to 50°C, which is more conducive to the dissolution of phenolic substances, free amino acids and reducing sugars.

[0015] In step (1), the amount of water added is 4 to 18 times the weight of the yam after it has been cut into sections. This allows the higher content of phenolic substances, free amino acids, and reducing sugars in the yam to dissolve in the water as much as possible during the grinding process and be removed during the subsequent dehydration process. This significantly reduces the degree of browning during the processing of the vermicelli, ensuring the color quality of the product. It also reduces the content of broken starch, resulting in vermicelli with a lower breakage rate and cooking loss rate, and a delicate and smooth texture. In addition, an addition of 4 to 18 times the amount of water is sufficient to fully leach out the phenolic substances, free amino acids, and reducing sugars, while adding more than 18 times the amount of water would increase production costs.

[0016] In step (2), the stirring and heat preservation time is 2 to 6 hours, which allows the starch in the yam to be fully soaked, which is conducive to the leaching of phenolic substances, free amino acids and reducing sugars. If the stirring and heat preservation time is greater than 6 hours, it will not cause phenolic substances, free amino acids and reducing sugars to leach out further, but will instead increase the production cost.

[0017] Preferably, in step (3), the amount of water added to the rice slurry is 5 to 10 times the mass of the rice, and the soaking time of the rice is 2.5 to 4.5 hours. This treatment can reduce the content of damaged starch when the rice is pulverized, so that the processed vermicelli has a lower breakage rate and cooking loss rate, and a delicate and smooth taste.

[0018] Preferably, in steps (1) and (3), the yam and rice are ground into slurries and then passed through an 80-180 mesh sieve to obtain yam slurry and rice slurry, respectively. In step (4), the water content in the wet rice flour and wet yam flour is 37%-43% by mass. Experiments have shown that using this moisture content avoids an increase in the breakage rate of the yam vermicelli due to excessively low or high moisture content in the wet flour, and is also sufficient to give the yam vermicelli a better color.

[0019] In step (5), the mixing ratio of wet rice flour and wet yam flour is 10:90 to 40:60 by mass, so that the yam vermicelli has a lower breakage rate and cooking loss rate.

[0020] The beneficial effects of this invention are:

[0021] This invention removes phenolic substances, free amino acids, and reducing sugars that cause high-temperature browning, as well as water-soluble proteins, amino acids, cellulose, minerals, and vitamins that affect the gel formation of rice vermicelli, by grinding, heat preservation, and dehydration of Chinese yam. This significantly reduces the degree of browning during product processing, improves the color quality of the product, and at the same time reduces the breakage rate and cooking loss rate of Chinese yam vermicelli, thereby improving the quality of the product.

[0022] In addition, the method of this invention for processing yam vermicelli eliminates the need for drying and other processes, resulting in lower costs compared to processing vermicelli using yam powder. Furthermore, the vermicelli produced by this invention has better color, lower breakage rate, and lower cooking loss rate compared to vermicelli processed directly from yam powder or yam paste, making it more competitive in the market. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0024] Example 1

[0025] A method for processing fresh yam into yam vermicelli includes the following steps:

[0026] (1) Peel and wash fresh yam, cut it into sections, then add 4 times its weight of water-milled slurry, and pass it through an 80-mesh sieve to obtain yam slurry;

[0027] (2) Heat the yam pulp obtained in step (1) to 50°C, stir and keep warm for 2 hours to obtain heat-treated yam pulp;

[0028] (3) Soak rice in water for 3 hours, then add 7.5 times its weight of water after filtering out the water and grind it into a paste. Pass the paste through an 80-mesh sieve to obtain rice paste.

[0029] (4) Dehydrate the heat-treated yam pulp obtained in step (2) and the rice pulp obtained in step (3) to a moisture content of 40% to obtain wet rice flour and wet yam flour.

[0030] (5) Mix the rice flour and yam flour obtained in step (4) at a mass ratio of 10:90, then cook them in a rice noodle machine, extrude the noodles, and cut them to obtain yam noodles.

[0031] Example 2

[0032] A method for processing fresh yam into yam vermicelli includes the following steps:

[0033] (1) Peel and wash fresh yam, cut it into sections, then add 11 times its weight of water-milled slurry, and pass it through a 130-mesh sieve to obtain yam slurry;

[0034] (2) Heat the yam pulp obtained in step (1) to 47.5℃, stir and keep warm for 4 hours to obtain heat-treated yam pulp;

[0035] (3) Soak rice in water for 4.5 hours, filter out the water, add 5 times its weight of water and grind into a paste, pass through a 130-mesh sieve to obtain rice paste;

[0036] (4) Dehydrate the heat-treated yam pulp obtained in step (2) and the rice pulp obtained in step (3) to a moisture content of 43% to obtain wet rice flour and wet yam flour.

[0037] (5) Mix the rice flour and yam flour obtained in step (4) at a mass ratio of 40:60, then cook them in a rice noodle machine, extrude the noodles, and cut them to obtain yam noodles.

[0038] Example 3

[0039] A method for processing fresh yam into yam vermicelli includes the following steps:

[0040] (1) Peel and wash fresh yam, cut it into sections, then add 18 times its weight of water-milled slurry, and pass it through a 180-mesh sieve to obtain yam slurry;

[0041] (2) Heat the yam pulp obtained in step (1) to 45°C, stir and keep warm for 6 hours to obtain heat-treated yam pulp;

[0042] (3) Soak rice in water for 2.5 hours, filter out the water, add 10 times its weight of water and grind into a paste, then pass through a 180-mesh sieve to obtain rice paste;

[0043] (4) Dehydrate the heat-treated yam pulp obtained in step (2) and the rice pulp obtained in step (3) to a moisture content of 37% to obtain wet rice flour and wet yam flour.

[0044] (5) Mix the rice flour and yam flour obtained in step (4) at a mass ratio of 25:75, then cook them in a rice noodle machine, extrude the noodles, and cut them to obtain yam noodles.

[0045] Example 4

[0046] A method for processing fresh yam into yam vermicelli includes the following steps:

[0047] (1) Peel and wash fresh yam, cut it into sections, then add 18 times its weight of water-milled slurry, and pass it through a 180-mesh sieve to obtain yam slurry;

[0048] (2) Heat the yam pulp obtained in step (1) to 50°C, stir and keep warm for 6 hours to obtain heat-treated yam pulp;

[0049] (3) Soak rice in water for 2.5 hours, filter out the water, add 10 times its weight of water and grind into a paste, then pass through a 180-mesh sieve to obtain rice paste;

[0050] (4) Dehydrate the heat-treated yam pulp obtained in step (2) and the rice pulp obtained in step (3) to a moisture content of 40% to obtain wet rice flour and wet yam flour.

[0051] (5) Mix the rice flour and yam flour obtained in step (4) at a mass ratio of 10:90, then cook them in a rice noodle machine, extrude the noodles, and cut them to obtain yam noodles.

[0052] Comparative Example 1: Preparation of yam vermicelli using yam powder

[0053] (1) Soak rice in water for 4.5 hours, filter out the water, add 5 times its weight of water and grind into a paste, pass through a 130-mesh sieve to obtain rice paste;

[0054] (2) Mix the commercially available yam powder and the rice paste obtained in step (1) at a mass ratio of 40:60 (dry weight of the two) evenly, and adjust the moisture content to 43% to obtain a premixed slurry.

[0055] (3) Place the premixed slurry obtained in step (2) into a rice noodle machine, extrude the rice noodles, and cut them to obtain yam rice noodles.

[0056] Comparative Example 2: Preparation of yam vermicelli using yam mud

[0057] (1) Peel and wash fresh yam, cut it into sections, steam it until cooked, mash it into a paste, and pass it through a 130-mesh sieve to obtain yam paste;

[0058] (2) Soak rice in water for 4.5 hours, filter out the water, add 5 times its weight of water and grind into a paste, then pass through a 130-mesh sieve to obtain rice paste;

[0059] (3) Mix the yam mud obtained in step (1) and the rice paste obtained in step (2) at a mass ratio of 40:60 of their dry weights, and adjust the moisture content to 43% to obtain a premixed slurry.

[0060] (4) Place the premixed slurry obtained in step (3) into a rice noodle machine, extrude the rice noodles, and cut them to obtain yam rice noodles.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Example 2 is that the yam pulp obtained in step (1) is not subjected to heat treatment, but is directly dehydrated; the other steps are the same as in Example 2.

[0063] Comparative Example 4

[0064] The difference between this comparative example and Example 2 is that the yam pulp obtained in step (1) is stirred at room temperature for 4 hours; the other steps are the same as in Example 2.

[0065] Comparative Example 5

[0066] The difference between this comparative example and Example 1 is that 3.5 times the amount of water-milled yam slurry was added in step (1); the other steps are the same as in Example 1.

[0067] Comparative Example 6

[0068] The difference between this comparative example and Example 3 is that 20 times the amount of water-milled yam slurry was added in step (1); the other steps are the same as in Example 3.

[0069] Comparative Example 7

[0070] The difference between this comparative example and Example 1 is that the yam slurry obtained in step (1) is stirred and kept warm for 1.5 hours; the other steps are the same as in Example 1.

[0071] Comparative Example 8

[0072] The difference between this comparative example and Example 3 is that the yam slurry obtained in step (1) was stirred and kept warm for 7 hours; the other steps are the same as in Example 3.

[0073] The process parameters for the above embodiments and comparative examples are shown in Table 1.

[0074] Table 1

[0075]

[0076] Test case

[0077] The yam vermicelli from the above examples and comparative examples was dried at 50°C until the water content was less than 13% by mass to obtain the product. Then, color and cooking quality tests were conducted, and the results are shown in Table 2. The product cost is also listed in Table 2.

[0078] The following are the test methods for color and cooking quality:

[0079] 1) Methods for measuring color:

[0080] The yam vermicelli was dried, pulverized, and passed through an 80-mesh sieve. The sieve-passing material was then measured using a colorimeter. L* represents black (0) and white (100); a* represents a color between red and green (100) and green (-80); b* represents a color between yellow and blue (100) and blue (-80).

[0081] 2) Method for determining the breakage rate:

[0082] Determination of the breakage rate of Chinese yam vermicelli: The method for determining the breakage rate was based on the People's Republic of China National Standard "Vermicelli" (GB / T 23587-2009).

[0083] From the sample, select vermicelli longer than 20cm, 10g per portion, and place them in the same container. Disperse them in boiling water at a weight ratio of 1:30 (sample:water). After simmering for 10 minutes, filter out the water, add cold water to cool and filter, and separate the vermicelli shorter than 10cm and longer than 10cm. Weigh them separately and calculate the breakage rate using the following formula:

[0084]

[0085] In the formula: m is the total mass of the soaked vermicelli in g; m1 is the mass of the vermicelli less than 10 cm in length after soaking in g.

[0086] 3) Method for determining cooking loss rate:

[0087] Test standard: Refer to the test method of "loss of weight in water" in the "Inspection Procedures for Imported and Exported Vermicelli (Strips)" (SNT 0927-2000) of the Entry-Exit Inspection and Quarantine Industry Standard of the People's Republic of China.

[0088] Determination Procedure: Weigh 100g of sample and place it in 750mL of boiling water. Maintain a gentle boil for 3 minutes. Use a stainless steel strainer to remove all the vermicelli. Stir the broth with a glass rod. Measure 1 / 10 of the total broth and place it in a pre-weighed weighing container. Evaporate to dryness in a water bath and then place in an oven at (105±2)℃ until constant weight is achieved. Weigh the dry matter and calculate the cooking loss rate (i.e., boiling loss) using the following formula:

[0089]

[0090] Where: m is the sample mass / g;

[0091] m1 is the mass of the dried sample and weighing dish in g;

[0092] m2 is the mass of the weighing dish before drying (g);

[0093] X represents the moisture content of the sample (%).

[0094] 10 is the conversion factor for the extracted sample.

[0095] Table 2

[0096]

[0097] The results in Table 2 above show that, in terms of color index, the yam vermicelli prepared in Examples 1-4 all have higher L* values, while their a* and b* values ​​are lower. This indicates that the color of the product processed by this invention is better than that of the products of Comparative Examples 1, 2, 3, 4, 5, and 7, and the degree of browning is less. The main reason why the yam vermicelli of Comparative Example 3 has the darkest color is that the raw materials contain a high content of phenolic active substances, proteins, free amino acids, and reducing sugars, which easily leads to enzymatic and non-enzymatic browning. Therefore, its color is worse than that of yam vermicelli prepared by other processing methods.

[0098] In terms of cooking quality indicators, the yam vermicelli from Examples 1-4 exhibited lower breakage rates and cooking loss rates, demonstrating superior cooking quality compared to existing technologies (Comparative Examples 1 and 2). Example 4 showed the lowest values, indicating the best quality. Comparative Example 2, using yam paste, showed the highest breakage rate and cooking loss rate, indicating the worst quality. This is mainly because the yam paste requires high-temperature, prolonged cooking during preparation, leading to high starch breakage and deteriorated starch gelation properties.

[0099] As shown in Table 2, the product prepared by this method has a significantly lower cost than the products of Comparative Example 1 and Comparative Example 2, and its color and cooking quality are also significantly better than those of Comparative Example 1 and Comparative Example 2, thus making it more competitive in the market.

[0100] This invention can be summarized in other specific forms that do not depart from the spirit or main features of the invention. The above embodiments of the invention are merely illustrative and not restrictive. Therefore, any minor modifications, equivalent variations, and alterations made to the above embodiments based on the essential technology of this invention fall within the scope of the invention's technical solution.

Claims

1. A method for processing fresh Chinese yam into Chinese yam vermicelli, characterized in that, Includes the following steps: (1) Peel and wash fresh yam, cut it into sections, then add water and grind it into a paste to obtain yam paste; (2) Heat the yam pulp obtained in step (1) to 45~50℃, stir and keep warm for a period of time to obtain heat-treated yam pulp; (3) Soak the rice in water, then grind it into a paste to obtain rice paste; (4) The heat-treated yam pulp obtained in step (2) and the rice pulp obtained in step (3) are subjected to pressure filtration and dehydration treatment to obtain wet rice powder and wet yam powder. (5) Mix the rice flour and yam flour obtained in step (4) evenly in proportion, then cook them in a rice noodle machine, extrude the noodles, and cut them to obtain the yam noodles.

2. The method for processing fresh yam into yam vermicelli according to claim 1, characterized in that, In step (1), the amount of water added is 4 to 18 times the mass of the yam after it is cut into sections.

3. The method for processing fresh yam into yam vermicelli according to claim 2, characterized in that, In step (2), the stirring and heat preservation time is 2~6h.

4. The method for processing fresh yam into yam vermicelli according to claim 3, characterized in that, in The water content in the rice flour and yam flour in step (4) is 37% to 43%.

5. The method for processing fresh yam into yam vermicelli according to claim 4, characterized in that, in In step (3), the amount of water added when grinding rice is 5 to 10 times the weight of rice; the soaking time for rice is 2.5 to 4.5 hours.

6. The method for processing fresh yam into yam vermicelli according to claim 5, characterized in that, In step (5), the mixing ratio of wet rice flour and wet yam flour is 10:90 to 40:60 by mass.

7. The method for processing fresh yam into yam vermicelli according to claim 6, characterized in that, In step (2), the yam paste is heated to 50°C.

8. The method for processing fresh yam into yam vermicelli according to claim 7, characterized in that, in In steps (1) and (3), yam and rice are ground into slurry and then passed through an 80-180 mesh sieve to obtain yam slurry and rice slurry, respectively.

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