Preparation method of modified corn flour and application thereof in tea noodles

Abstract

The application discloses a preparation method of modified corn flour and application of the modified corn flour in tea noodles and belongs to the technical field of flour modification. First, the method for preparing the modified corn flour comprises the following steps: adding sodium trimetaphosphate, tea polysaccharide, chitosan and NaCl to prepare corn flour milk; performing crosslinking reaction under the condition of 38-45 DEG C; and performing enzymolysis reaction under the condition of 43+ / -2 DEG C, so as to obtain crosslinking-enzymolysis composite modified corn flour. Then, the crosslinking-enzymolysis composite modified corn flour, green tea extract, guar gum, salt and gluten powder are mixed to prepare green tea corn noodles. The green tea corn noodles prepared by the method have similar taste to traditional wheat noodles, good strength and dough performance, low glycemic index and are suitable for diabetics.

Description

Technical Field

[0001] The invention belongs to the technical field of corn flour modification, and in particular relates to a preparation method of modified corn flour and application of the modified corn flour in tea noodles. Background Art

[0002] Cornmeal comes in different sizes and textures. It's rich in nutrients and can be found in a wide variety of foods. Corn contains significant amounts of lecithin, linoleic acid, cereal alcohol, vitamin E, and cellulose. It boasts numerous health benefits, including lowering blood pressure and blood lipids, combating arteriosclerosis, preventing colon cancer, enhancing beauty, and delaying aging. It's also a great choice for diabetics. Cornmeal retains all the nutritional value and conditioning properties of corn while improving the unpleasant taste and indigestion associated with coarse-grain flours.

[0003] Tea contains a large amount of catechins, creatine, folic acid, pantothenic acid, etc. These substances can produce a variety of biological activities on the human body. First of all, they have a certain protective effect on the cardiovascular system. The tea polyphenols in tea can improve the human body's microcirculation, have a certain promoting effect on fat metabolism, and can reduce the occurrence of hyperlipidemia.

[0004] After the inventors’ previous research on the effect of tea powder added to starch on the texture of tea noodles, they found that the effect of polyphenols on the gelatinization properties of starch is commonly studied in DSC research. o ), peak gelatinization temperature (T p )、final gelatinization temperature(T c ) and gelatinization enthalpy (ΔH) are used to characterize the gelatinization properties of starch. The water ratio during starch gelatinization affects the interaction between polyphenols and starch. Black tea extract increases the gelatinization temperature and gelatinization enthalpy of corn flour and rice starch. Increasing the black tea extract dosage from 5% to 15% increases the gelatinization temperature and gelatinization enthalpy of rice starch by 2-4°C and 1 J / g, respectively. However, it has no significant effect on the gelatinization properties of potato starch. The -OH and -COOH groups in polyphenols may interact with water molecules and -OH groups in starch molecules through hydrogen bonding, thereby altering the gelatinization properties of starch molecules.

[0005] Previous studies have shown that under hydrothermal treatment, tea polyphenols reduce the energy required for starch gelatinization, lowering gelatinization viscosity, disrupting the resulting three-dimensional network structure, and weakening elastic properties. This trend has a negative impact on the textural properties of Chinese dried noodles. Compared to neutral environments, acidic and alkaline environments have a stronger influence on the starch-tea polyphenol interaction during hydrothermal treatment. This is related to the changes in the scale structure and functional properties caused by the hydrolysis of starch molecules under acidic and alkaline conditions. The interaction between tea polyphenols and wheat starch is primarily characterized by hydrogen bonding at C2, C3, and C6 in acidic environments; π-π conjugation at the α-1,4 glycosidic bond in neutral environments; and hydrogen bonding at C2 in alkaline environments.

[0006] The above research results show that when black tea extract is added to starch, the elasticity of the noodles prepared from starch is weakened, the structure is not dense, the taste is not chewy, and there is a loose taste in the mouth, which does not meet the human requirements for taste. Corn flour is a free food that is beneficial to the health of diabetics, but it has technical problems such as lack of texture and stickiness and cannot be made into tea corn noodles. For this reason, the inventors first improved the corn flour by changing the hydrogen bonds between the -OH and -COOH groups in polyphenols and starch, and provided a black tea noodle that not only maintains the texture of general wheat flour, but also has a relatively dense organizational structure and a taste that meets the needs of current consumers. At the same time, it has the effects of nourishing the stomach and lowering blood sugar. Summary of the Invention

[0007] The present invention aims to address technical issues such as corn flour's inferior texture to wheat flour and its inability to form gluten-free noodles after adding green tea extract. The invention provides a modified corn flour that effectively incorporates the tea polyphenols in green tea extract and, together with guar gum and gluten, creates a new gluten-like texture, resulting in noodles with a texture similar to wheat flour. Specifically, the corn flour modification method is as follows.

[0008] ① Add 1-3% sodium trimetaphosphate, 3-8% tea polysaccharides, 1-5% chitosan and 0.1-3% NaCl to corn flour according to the mass ratio, then add 1-2 times the volume of deionized water based on the mass of corn starch, mix thoroughly and evenly to make corn flour milk;

[0009] ② Adjust the pH value of corn flour emulsion to 9.5-11 with NaOH, and carry out cross-linking reaction at 38-45°C for 1-2 hours. After the cross-linking is completed, wash the corn flour emulsion with deionized water, dry it, grind it and sieve it through a 40-100 mesh sieve to obtain cross-linked tea polysaccharide corn flour;

[0010] ③ The cross-linked tea polysaccharide corn flour obtained in step ② was dissolved in deionized water, and the pH was adjusted to 5.5 with an HCl aqueous solution. 1% saccharifying enzyme was added according to the mass ratio of the cross-linked tea polysaccharide corn flour. The enzymatic hydrolysis reaction was carried out at 43±2°C for 8-12 hours. After the enzymatic hydrolysis was completed, the supernatant was removed, the precipitate was washed with deionized water, and dried through a 40-100 mesh sieve to obtain a cross-linked-enzymatic hydrolysis composite modified corn flour.

[0011] Wherein, in the step ③, the centrifugation is specifically carried out at 3000-4500 r / min for 10-30 min.

[0012] The present invention also provides corn flour tea noodles, the dough ingredients of which include: cross-linked and enzymatically modified corn flour, green tea extract, guar gum, salt, and gluten. The cross-linked and enzymatically modified corn flour accounts for 60-80% by mass, the green tea extract accounts for 10-30% by mass, the guar gum accounts for 3-8% by mass, the salt accounts for 0.1-1% by mass, and the gluten accounts for 1.9-6% by mass.

[0013] The preparation method of the corn flour tea noodles comprises the following steps: uniformly mixing modified corn flour, green tea extract, guar gum, salt and gluten according to a mass ratio of 60-80% of cross-linked-enzymatic composite modified corn flour, 10-30% of green tea extract, 3-8% of guar gum, 0.1-1% of salt and 1.9-6% of gluten, adding 25-30% of pure water to knead the mixed powder evenly, pressing and cutting into strips to prepare corn flour tea noodles. Beneficial effects

[0014] Compared to wheat flour, corn flour lacks gluten, so its properties are quite different from those of wheat flour. However, when wheat flour is mixed with tea leaves, tea extracts, or tea polyphenols, it forms a relatively hard or easily aged substance, which seriously affects the taste. The applicant has found that after corn flour is modified and then guar gum, gluten, and green tea extract are added, it can simulate the gluten of wheat flour. The main principle is to first form a cross-linked structure with corn starch through tea polysaccharides, chitosan, etc., and then form a network structure through enzymatic hydrolysis. The modified corn starch with a network structure is then filled with guar gum and green tea extract to form a structure similar to gluten protein. At the same time, it also has a certain elasticity and compression space, resulting in the green tea corn noodles prepared by it having a taste similar to traditional wheat flour noodles. The source of its elasticity mainly depends on the hollow structure of the modified cross-linked-enzymatic hydrolyzed corn flour. If the spatial structure is insufficient, the prepared tea noodles will have a relatively hard texture. Otherwise, they will easily fall apart and cannot form gluten or the chewiness of noodles.

[0015] This invention, by modifying corn flour and compounding it with guar gum and green tea extract, produces corn noodles similar to wheat noodles. This solves the problem of wheat flour's high absorption rate and rapid blood sugar rise, offering advantages for patients with high blood sugar levels. Corn flour slows down blood sugar rises and has a similar taste to wheat flour, suggesting promising market prospects. It provides a food source for diabetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the electron microscope scanning image of embodiment 1~3 of the present invention

[0017] Figure 2 It is the electron microscope scanning image of comparative example 1~3 of the present invention Implementation Method

[0018] The technical solution of the present invention is further described in detail below through specific embodiments and drawings.

[0019] In the present invention, corn flour was commercially available, tea polysaccharides were purchased from Nanjing Tongying Biotechnology Co., Ltd., and other reagents were of analytical grade.

[0020] Green tea extract is a powdered solid obtained by water-soluble extraction of green tea and concentration and drying. Black tea extract is a powdered solid obtained by water-soluble extraction of black tea and concentration and drying. The green tea extract and black tea extract in the present invention are provided by Damin Food (Zhangzhou) Co., Ltd. Example 1

[0021] This embodiment provides a method for modifying corn flour, comprising the following steps:

[0022] Accurately weigh 1000 g of corn flour, add 20 g of sodium trimetaphosphate, 50 g of tea polysaccharides, 20 g of chitosan and 2 g of NaCl, then add 1000 mL of deionized water, mix thoroughly and evenly to prepare corn flour milk.

[0023] The pH value of corn flour milk was adjusted to 10 with NaOH, and the cross-linking reaction was carried out at 40°C for 1 hour. After the cross-linking was completed, the corn flour milk was washed three times with deionized water, dried, crushed and sieved through a 40-100 mesh sieve to obtain cross-linked tea polysaccharide corn flour.

[0024] The cross-linked tea polysaccharide corn flour obtained in step 2 was dissolved in 100 ml of water, and the pH was adjusted to 5.5 with an HCl aqueous solution. 1% saccharifying enzyme was added according to the mass ratio of the cross-linked tea polysaccharide corn flour. The enzymatic hydrolysis reaction was carried out at 43° C. for 10 h. After the enzymatic hydrolysis was completed, the mixture was centrifuged at 3000 r / min for 20 min, the supernatant was removed, and the precipitate was washed 3 times with deionized water and dried through a 40-mesh sieve to obtain a cross-linked-enzymatic hydrolysis composite modified corn flour.

[0025] Based on the modified corn flour, after compounding with green tea extract, a tea corn noodle similar to traditional noodles was obtained.

[0026] Weigh 700g of modified corn flour, 200g of green tea extract, 50g of guar gum, 5g of salt, and 45g of gluten, mix well, and place in a dough mixer. Add 250g of purified water. Turn on the mixer, press, and cut into strips to prepare cornmeal tea noodles.

[0027] To ensure consistency, the dough mixer parameters were uniformly set: mixing at 90 rpm for 2 minutes, then increasing the speed to 120 rpm for 10 minutes. The resulting dough rested for 30 minutes before being fed into the pilot noodle production line. After five rolling cycles, the dough sheet thickness gradually decreased to 1.2 mm. After being cut and shortened, fresh noodles were formed, each 2.5 mm wide and 300 mm long. Example 2

[0028] The modified corn flour of Example 1 was compounded with green tea extract to obtain tea corn noodles similar to traditional noodles.

[0029] Weigh 800g of modified corn flour, 100g of green tea extract, 80g of guar gum, 1g of salt, and 19g of gluten, mix thoroughly, and place in a dough mixer. Add 300g of purified water. Turn on the mixer, press, and cut into strips to prepare cornmeal tea noodles.

[0030] To ensure consistency, the dough mixer parameters were uniformly set: mixing at 90 rpm for 2 minutes, then increasing the speed to 120 rpm for 10 minutes. The resulting dough rested for 30 minutes before being fed into the pilot noodle production line. After five rolling cycles, the dough sheet thickness gradually decreased to 1.2 mm. After being cut and shortened, fresh noodles were formed, each 2.5 mm wide and 300 mm long. Example 3

[0031] The modified corn flour of Example 1 was compounded with green tea extract to obtain tea corn noodles similar to traditional noodles.

[0032] Weigh 600g of modified corn flour, 300g of green tea extract, 30g of guar gum, 10g of salt, and 60g of gluten, mix well, and place in a dough mixer. Add 280g of purified water. Turn on the mixer, press, and cut into strips to prepare cornmeal tea noodles.

[0033] To ensure consistency, the dough mixer parameters were uniformly set: mixing at 90 rpm for 2 minutes, then increasing the speed to 120 rpm for 10 minutes. The resulting dough rested for 30 minutes before being fed into the pilot noodle production line. After five rolling cycles, the dough sheet thickness gradually decreased to 1.2 mm. After being cut and shortened, fresh noodles were formed, each 2.5 mm wide and 300 mm long. Comparative Example 1

[0034] The corn flour before modification in Example 1 was compounded with green tea extract to obtain tea corn noodles similar to traditional noodles.

[0035] Weigh 700g corn flour, 200g green tea extract, 50g guar gum, 5g salt, and 45g gluten, mix them evenly, put them into a dough mixer, add 250g pure water, turn on the dough mixer, press the dough, and cut it into strips to prepare corn flour tea noodles.

[0036] To ensure consistency, the dough mixer parameters were uniformly set: mixing at 90 rpm for 2 minutes, then increasing the speed to 120 rpm for 10 minutes. The resulting dough rested for 30 minutes before being fed into the pilot noodle production line. After five rolling cycles, the dough sheet thickness gradually decreased to 1.2 mm. After being cut and shortened, fresh noodles were formed, each 2.5 mm wide and 300 mm long. Comparative Example 2

[0037] The corn flour before modification in Example 1 was compounded with green tea extract to obtain tea corn noodles similar to traditional noodles.

[0038] Weigh 800g corn flour and 200g green tea extract, mix them evenly and put them into a dough mixer, add 250g pure water, turn on the dough mixer, press the dough, and cut into strips to prepare corn flour tea noodles.

[0039] To ensure consistency, the dough mixer parameters were uniformly set: mixing at 90 rpm for 2 minutes, then increasing the speed to 120 rpm for 10 minutes. The resulting dough rested for 30 minutes before being fed into the pilot noodle production line. After five rolling cycles, the dough sheet thickness gradually decreased to 1.2 mm. After being cut and shortened, fresh noodles were formed, each 2.5 mm wide and 300 mm long. Comparative Example 3

[0040] This comparative example provides a method for preparing traditional wheat flour. 1000g of wheat flour is weighed and placed in a dough mixer, 250g of pure water is added, the dough mixer is turned on, and the dough is pressed and cut into strips to prepare traditional noodles.

[0041] To ensure consistency, the dough mixer parameters were uniformly set: mixing at 90 rpm for 2 minutes, then increasing the speed to 120 rpm for 10 minutes. The resulting dough rested for 30 minutes before being fed into the pilot noodle production line. After five rolling cycles, the dough sheet thickness gradually decreased to 1.2 mm. After being cut and shortened, fresh noodles were formed, each 2.5 mm wide and 300 mm long.

[0042] To determine the optimal cooking time for noodles, place 25g of noodles in a 500mL beaker containing 300mL of boiling distilled water. Every 10 seconds, remove a section of noodles and sandwich them between two transparent glass plates. After rolling, observe whether the opaque substance in the center of the noodles disappears. The optimal cooking time is determined by measuring the steaming water absorption rate. After the optimal cooking time is reached, the surface water of the noodles is absorbed dry and weighed. The steaming water absorption rate is calculated using the formula: steaming water absorption rate (%) = noodle mass after steaming (g) / noodle mass before steaming (g). Viscosity is determined by the following method:

[0043] Noodle textural properties were determined by steaming 100g of noodles for the optimal cooking time. The noodles were then rinsed in 26-27°C tap water for 10 seconds and placed in a plastic container, where they were gently tapped 10 times to remove surface moisture. Three evenly sized noodles were cut into 6.0mm strips. Five randomly selected noodles were placed parallel to each other on the instrument platform and compressed using a TA-47W probe. The test parameters were: pre-test probe speed of 4mm / s, test speed of 1mm / s, and post-test speed of 1mm / s; the compression strain was 70% of the noodle thickness. The test parameters were hardness (g), viscoelasticity, cohesion, chewiness, and resilience. Each sample was tested within 6 minutes to minimize textural error. Results were considered valid when the coefficient of variation of the replicated results for each sample group was no greater than 5%.

[0044] Determination of noodle color characteristics: First, calibrate the colorimeter with a white board. Stack three layers of fresh noodles together and measure two of them. Take two points on each of the upper and lower surfaces of the noodles for measurement. After each sample is measured, 8 groups of L * 、a * 、b * value.

[0045] Glycemic Index: The glycemic index is defined as the incremental area under the curve (AUC) for the two-hour blood glucose response following a 12-hour fast and the ingestion of a meal containing a certain amount of available carbohydrate (usually 50 grams). The AUC for the test food is divided by the AUC of the standard and then multiplied by 100.

[0046] The results of cooking and texture properties are shown in the table below:

[0047] Group Steaming time Cooking yield / % Hardness / N Cohesion chewability Resilience Glycemic index Example 1 6¢30² 152.6±3.4 17.78±0.18 0.69±0.01 10.03±0.15 0.98±0.01 61.3 Example 2 6¢35² 154.1±1.2 17.73±0.19 0.70±0.04 10.78±0.10 0.96±0.02 63.1 Example 3 6¢20² 153.7±2.9 17.12±0.34 0.66±0.02 10.93±0.12 0.93±0.01 62.8 Comparative Example 1 6¢24² 147.1±2.0 13.76±0.12 0.55±0.01 9.00±0.03 0.70±0.01 66.3 Comparative Example 2 6¢20² 144.0±4.0 14.77±0.79 0.55±0.02 8.98±0.05 0.77±0.02 67.9 Comparative Example 3 6¢33² 155.2±0.2 17.12±0.56 0.71±0.02 10.45±0.08 0.91±0.02 81.3

[0048] The results of color property determination are shown in the table below:

[0049] Group L* a* b* Example 1 81.63±2.00 1.22±0.83 18.34±1.37 Example 2 83.66±0.95 0.87±0.37 17.39±0.89 Example 3 84.33±0.73 0.78±0.20 16.62±0.88 Comparative Example 1 83.14±0.59 0.81±0.14 17.78±0.90 Comparative Example 2 82.46±1.38 1.13±0.68 18.25±1.29 Comparative Example 3 84.01±1.05 0.84±0.42 16.93±1.51

Claims

1. A method for preparing modified corn flour, characterized in that: The preparation method of the modified corn flour specifically comprises the following steps: ① Add 1-3% sodium trimetaphosphate, 3-8% tea polysaccharides, 1-5% chitosan and 0.1-3% NaCl to corn flour by mass ratio, then add 1-2 times the volume of deionized water based on the mass of corn starch, mix thoroughly and evenly to make corn flour milk; ② The pH value of the corn flour emulsion was adjusted to 9.5-11 with NaOH, and the cross-linking reaction was carried out at 38-45°C for 1-2 hours. After the cross-linking was completed, the corn flour emulsion was washed with deionized water, dried, crushed and sieved through a 40-100 mesh sieve to obtain cross-linked tea polysaccharide corn flour; ③ The cross-linked tea polysaccharide corn flour obtained in step ② was dissolved in deionized water and the pH was adjusted to 5.5 with an HCl aqueous solution. 1% saccharifying enzyme was added according to the mass ratio of the cross-linked tea polysaccharide corn flour. The enzymatic hydrolysis reaction was carried out at 43±2°C for 8-12 hours. After the enzymatic hydrolysis was completed, the supernatant was removed, and the precipitate was washed with deionized water and dried through a 40-100 mesh sieve to obtain the cross-linked-enzymatic hydrolysis composite modified corn flour.

2. The method for preparing modified corn flour according to claim 1, wherein: In step ③, the centrifugation is performed at 3000 to 4500 rpm for 10 to 30 min.

3. An application of the cross-linked-enzymatically modified corn flour prepared by the method for preparing the modified corn flour according to claim 1, characterized in that: The cross-linking-enzymatic hydrolysis composite modified corn flour is used for preparing tea noodles.

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