Method for reducing malondialdehyde in fried flour product through methyl cellulose wrapping paste

Abstract

The invention discloses a method for reducing malondialdehyde in fried flour products through methyl cellulose wrapping paste. The method comprises the following steps: adding glycerol into hot water at the temperature of 70-80 DEG C, adding methyl cellulose while stirring, then adding ice water, and completely dissolving to obtain methyl cellulose coating paste liquid; weighing flour, table salt and a leavening agent, putting the weighed flour, table salt and leavening agent into a dough mixer, uniformly mixing, adding hot water, kneading until the dough is smooth and non-sticky, and after the dough is fermented, pressing the dough to prepare a flour product blank; and coating the surface of the flour product blank with the prepared methyl cellulose coating paste liquid, airing at room temperature, and frying in a frying pan. The fried flour product blank is coated with the methylcellulose, so that the content of malondialdehyde in the fried flour product can be remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of food, and particularly relates to a method for reducing malondialdehyde in fried noodle products by coating with methylcellulose. Background Art

[0002] During the high-temperature frying process, the unsaturated fatty acids in the frying oil undergo chemical reactions such as thermal oxidation, hydrolysis and polymerization at high temperatures, which will produce non-volatile aldehyde hazards such as malondialdehyde (MDA) that are potentially harmful to human health. This type of toxic substance is widely present in fried foods and is present in high levels. It is a typical chemical hazard associated with oil oxidation.

[0003] In order to improve the safety of fried foods, reduce the content of MDA in fried foods and reduce microbial contamination, the existing technology mainly reduces the frying temperature and time, uses antioxidants such as rosemary in the frying process, selects oils with high unsaturated fatty acid content, reduces the number of times the frying oil is used, etc. For example, Feng Min et al. used irradiation and antioxidants to reduce MDA in grain foods (Journal of Jiangsu Agricultural Sciences 2013, 29 (02)); Patent CN101880598A discloses reducing MDA in feed by molecular distillation; Patent CN101805669A discloses removing MDA from oil by adding concentrated sulfuric acid and concentrated phosphoric acid. Although the methods in these patents or documents can also reduce some MDA content, these methods have obvious defects, such as the need for special molecular distillation equipment or the need to add food additives or concentrated sulfuric acid. In addition, while reducing the MDA content, the quality of fried flour products will be reduced and wastewater will be generated. Patent CN114568475A discloses an edible mixed film for fried food and a preparation method thereof. The edible mixed film mainly uses sodium alginate, guar gum and sodium carboxymethyl cellulose as main film-forming materials to make a film liquid, which is coated before the food is fried. Although it can also reduce the MDA content, it still has obvious disadvantages: (1) the mixed additives will react with each other, especially sodium carboxymethyl cellulose, which is very reactive and easily reacts with other additives, which may bring new hazards to food safety. Therefore, considering food safety, a single additive is used as much as possible; (2) sodium alginate in the mixed additive is easy to react with amino compounds in food at high temperature to undergo Maillard reaction, deepen the color of the food and reduce the sensory quality; (3) when sodium carboxymethyl cellulose is used alone, it contains a large number of carboxyl groups in its molecular chain. These groups have strong hydrophilicity and therefore have good water solubility but poor oil resistance. In addition, the stability of CMC-Na during high-temperature frying is poor, the battering effect is poor at low viscosity, and the battering liquid easily falls off, which cannot play the role of oil barrier and MDA reduction. (4) The sodium carboxymethyl cellulose molecules in the mixed additives contain a large number of carboxyl groups, which makes the molecules hydrophilic and bioavailable, and are easily contaminated by microorganisms.

[0004] In summary, based on the problems existing in the prior art such as the need for low-temperature frying or vacuum frying equipment or the addition of too many antioxidants and preservatives, there is an urgent need to provide a simple, low-cost, safe and reliable method to reduce MDA in fried noodle products. Summary of the invention

[0005] The object of the present invention is to provide a method for reducing the content of malondialdehyde in fried flour products by coating with methylcellulose, so as to overcome the technical problem of reducing the content of malondialdehyde in fried flour products by adding chemical substances or using expensive frying equipment in the prior art.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] The invention discloses a coating material for reducing malondialdehyde in fried noodle products, wherein the coating material is a methylcellulose coating liquid, and the concentration of the methylcellulose coating liquid is 1.0% to 1.5%. The coating material is evenly coated on the surface of the noodle product to be fried, and the methylcellulose accounts for no more than 1% of the total weight of the food after coating.

[0008] The invention discloses a method for reducing malondialdehyde in fried noodle products by coating with methylcellulose, comprising the following steps:

[0009] (1) Add glycerol to hot water at a temperature of 70 to 80° C., slowly add methyl cellulose while stirring, and then slowly add an appropriate amount of ice water. After all the methyl cellulose is dissolved, a methyl cellulose paste is obtained, which is placed in a refrigerator at 4 to 10° C. for 24 hours for use;

[0010] (2) weighing flour, salt, and leavening agent into a dough mixer, mixing well, adding hot water at a temperature of 50 to 55° C., and kneading until the dough is smooth and not sticky, taking out the dough, and letting the dough rise at room temperature. After the dough has risen, pressing the dough into a dough product blank;

[0011] (3) coating the noodle product blank of step (2) with the methyl cellulose coating liquid prepared in step (1), placing it at room temperature to dry, and then frying it in an oil pan at 180-185° C. for 2-4 minutes, removing it from the pan, draining the oil, and cooling it to obtain a methyl cellulose coated fried noodle product.

[0012] Furthermore, in step (1), the methyl cellulose is food grade and complies with the standard GB 1886236-2084.

[0013] Furthermore, in step (1), the mass ratio of methyl cellulose, glycerol, hot water and ice water is 1-3:6:70:130.

[0014] Furthermore, in step (1), the concentration of the methylcellulose coating solution is 1.0% to 1.5%.

[0015] Furthermore, in step (2), by weight:

[0016] 90-100 parts flour

[0017] 1.35-1.5 parts salt

[0018] 2.7-3 parts of leavening agent

[0019] 50-55 parts water

[0020] The leavening agent is an aluminum-free leavening agent.

[0021] Furthermore, in step (3), the specific operation of coating is: coating the surface of the dough product with a layer of methyl cellulose coating liquid with a thickness of 0.2 to 0.3 cm evenly, and drying it at room temperature for 1 hour.

[0022] Furthermore, in step (3), the oil used for frying can be vegetable oil or animal oil, including but not limited to soybean oil, peanut oil, rapeseed oil, cottonseed oil, palm oil, etc.

[0023] The invention provides a fried noodle product coated with methyl cellulose prepared by the preparation method.

[0024] The fried flour products obtained by the above preparation method are not limited to flour products such as fried dough sticks, fried cakes, dough nests, hemp leaves, sazi, and noodles.

[0025] The present invention uses food additive methyl cellulose (Methyl Cellulose) as a raw material, mixes it with edible glycerol, hot water and ice water to prepare a methyl cellulose paste liquid of appropriate concentration, and evenly coats the liquid on the surface of the noodle product blank, dries, fries and cools it to obtain the methyl cellulose paste fried noodle product. The preparation method provided by the present invention is simple, and the oil in the fried noodle product is extracted by Soxhlet extraction after cooling, and then the oil is derivatized and then the MDA is determined. The results show that the content of malondialdehyde in the fried noodle product obtained by the method of the present invention is significantly reduced, and the MDA content is reduced by no less than 20% compared with the unpasteurized sample.

[0026] MDA in fried noodle products is a product caused by free radicals generated by the oxidation of unsaturated fatty acids during frying. The inventors surprisingly found that MC can prevent the penetration of oil and fat after being coated in batter, thereby preventing the occurrence of oil oxidation, thereby reducing the generation of MDA. In addition, since methylcellulose is a methyl ether of cellulose, a large number of hydroxyl groups in the molecule are replaced by methyl groups, forming a relatively stable ether bond structure. Using methylcellulose to coat fried noodle products can reduce the risk of microbial infection, and it is not easy to be decomposed by enzymes produced by microorganisms without adding preservatives, thereby extending the shelf life of food.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) The present invention provides a method for reducing malondialdehyde in fried noodle products by coating with methylcellulose. The coated noodle products can not only prevent oil from penetrating deeply into the food during frying, thereby reducing the oil content and the malondialdehyde content in the fried noodle products.

[0029] (2) The present invention provides a method for reducing malondialdehyde in fried noodle products by coating with methylcellulose, which extends the application of methylcellulose and opens up a new method for reducing malondialdehyde in fried noodle products by coating with methylcellulose and reducing or eliminating the need for preservatives.

[0030] (3) The method of reducing malondialdehyde in fried flour products by coating with methylcellulose provided by the present invention is simple to operate, rapid, low-cost, non-toxic, harmless and pollution-free, does not require the use of special distillation equipment or the addition of antioxidants or preservatives, is highly safe, and is suitable for the promotion and use of fried foods. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the liquid chromatogram of MDA standard.

[0032] Figure 2 This is a comparison chart of the reduction degree of malondialdehyde during the frying process of noodle products with different batter coating liquids. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention is further described below in conjunction with examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. If the manufacturer of the reagents or instruments used is not indicated, they are deemed to be conventional products that can be purchased commercially.

[0034] Example 1

[0035] This embodiment provides a method for reducing malondialdehyde in fried flour products by methylcellulose batter coating, wherein the batter coating material is 1.0% methylcellulose batter liquid, the oil cake frying temperature is 180° C., and the frying time is 2 min, comprising the following steps:

[0036] (1) Add 6 g of edible glycerin to 70 g of hot water (80°C), slowly add 2 g of methyl cellulose while stirring, and then slowly add 130 g of ice water (0°C). After all the ingredients are dissolved, place in a refrigerator at 4°C for 24 hours for later use.

[0037] (2) Weigh flour, salt, and leavening agent according to Table 1 in a dough mixer, mix well, add 50°C hot water, and knead until the dough is smooth and not sticky. Then, take out the dough and place it in an iron plate, cover it with two layers of wet gauze and a layer of dry towel, and let the dough rise at room temperature for 1 hour. After the dough has risen, press it to a thickness of about 0.5 cm, and use a mold to make a number of dough cakes with a diameter of 5.7 cm.

[0038] Table 1 Basic recipe of dough

[0039]

[0040] (3) Coat the surface of the dough with the prepared 1.0% methyl cellulose batter to a thickness of about 0.2 cm, place it at room temperature for 1 hour to dry, and use the uncoated sample as the control group, fry it in 180°C cooking oil for 2 minutes, remove it, drain the oil, and cool it for 10 minutes to obtain the oil cake sample to be tested.

[0041] The determination of the malondialdehyde content in fried flour products comprises the following steps:

[0042] (1) Extraction of fat from fried cakes

[0043] The freeze-dried oil cake samples and control group samples were crushed, and the crushed samples were weighed and placed in a 250mL stoppered conical flask according to the sample processing method in GB / T 5009.56-2003. A proper amount of petroleum ether (boiling range: 30℃-60℃) was added. After standing overnight, the samples were filtered with filter paper and the solvent was recovered under reduced pressure to prepare the oil for MDA determination.

[0044] (2) Preparation of MDA standard solution and sample derivatization

[0045] MDA standard solution configuration:

[0046] Accurately weigh 0.315 g of 1,1,3,3-tetraethoxymethane, dilute to 1000 mL with 50% (v / v) ethanol-water mixture, accurately weigh 10 mL of the above solution in a 100 mL volumetric flask, dilute to 100 mL with 50% (v / v) ethanol-water mixture to obtain a 10 μg / mL MDA standard stock solution, and obtain the MDA standard curve as shown in Table 2. The liquid chromatogram of the MDA standard is shown in Figure 1 The solution was diluted step by step to 0.02, 0.1, 0.5, 1.0, 2.0, 5.0, and 10.0 μg / mL MDA standard solution for later use.

[0047] Table 2

[0048]

[0049] Derivatization of oil samples:

[0050] Take 2g of oil sample in a 15mL centrifuge tube, add 5mL of 50% (v / v) ethanol-water mixture, vortex, centrifuge at 5000g for 5min, remove the lower layer, repeat the above operation, mix the lower layer solutions obtained twice, add 500μL 2',4-dinitrophenylhydrazine (DNPH), vortex for 1min, place in a 60℃ water bath for derivatization for 2h under light-proof conditions, and cool with ice water after derivatization. Add 5mL of dichloromethane, vortex and centrifuge, remove the lower layer, repeat the above operation twice, combine the lower layer solutions obtained three times, blow nitrogen to nearly dryness, add 5mL of acetonitrile to dissolve, pass through a 0.45μm organic microporous filter membrane, and wait for HPLC analysis. The MDA standard solution and the oil sample are derivatized in the same way.

[0051] (3) Determination of MDA content in samples

[0052] RP-HPLC-PDA (reverse phase high performance liquid chromatography-diode array detector) was used for determination, and the determination conditions were: Agilent ZORBAX Elipse XDB-C18 reverse phase chromatographic column (4.6×250mm, 5μm); mobile phase: phase A: acetonitrile; phase B: pure water; elution mode (v / v): MDA: acetonitrile: water = 45:55, isocratic elution at 1.0mL / min for 15min; detection wavelength: MDA: 310nm; column temperature, 30°C; injection volume, 10μL.

[0053] Test results: Figure 2 As shown, the MDA content in the fried noodle oil prepared in Example 1 was reduced from 0.63±0.01 μg / g oil sample of the unbattered noodle product to 0.49±0.01 μg / g oil sample, a decrease of 20.63%.

[0054] Example 2

[0055] This embodiment provides a method for reducing malondialdehyde in fried flour products by methylcellulose batter coating, wherein the batter coating material is 1.5% methylcellulose batter liquid, the oil cake frying temperature is 185° C., and the frying time is 2 min, comprising the following steps:

[0056] (1) Add 6 g of edible glycerin to 70 g of hot water (80°C), slowly add 3 g of methyl cellulose while stirring, and then slowly add 130 g of ice water (0°C). After all the ingredients are dissolved, place in a refrigerator at 4°C for 24 hours for later use.

[0057] (2) According to Table 3, weigh flour, salt, and leavening agent in a dough mixer, mix well, add 50°C hot water, and knead until the dough is smooth and not sticky. Then, take out the dough and place it in an iron plate, cover it with two layers of wet gauze and a layer of dry towel, and let the dough rise at room temperature for 1 hour. After the dough has risen, press it to a thickness of about 0.5 cm, and use a mold to make a number of dough cakes with a diameter of 5.7 cm.

[0058] Table 3 Basic recipe of dough cake

[0059]

[0060] (3) The surface of the dough was coated with a 1.5% methyl cellulose coating liquid to a thickness of about 0.2 cm. The dough was placed at room temperature for 1 hour to dry. The uncoated sample was used as a control group and fried in 185°C cooking oil for 2 minutes. The sample was removed from the oil, drained, and cooled for 10 minutes to obtain the oil cake sample to be tested.

[0061] The malondialdehyde content in the fried noodle product of Example 2 was measured using the same method as Example 1.

[0062] Test results: Figure 2 As shown, the MDA content in the fried noodle oil prepared in Example 2 was reduced from 0.63±0.01 μg / g oil sample of the unbattered noodle product to 0.46±0.01 μg / g oil sample, a decrease of 26.98%.

[0063] Comparative Example

[0064] The methylcellulose batter in Example 2 was replaced with a carboxymethylcellulose batter of the same concentration, and the reduction of malondialdehyde in fried noodle products was tested, comprising the following steps:

[0065] (1) Add 6 g of edible glycerin to 70 g of hot water (80°C), slowly add 2 g of sodium carboxymethyl cellulose while stirring, and then slowly add 130 g of ice water (0°C). After all the ingredients are dissolved, place in a refrigerator at 4°C for 24 hours for later use.

[0066] (2) According to Table 4, weigh flour, salt, and leavening agent in a dough mixer, mix well, add 50°C hot water, and knead until the dough is smooth and not sticky. Then, take out the dough and place it in an iron plate, cover it with two layers of wet gauze and a layer of dry towel, and let the dough rise at room temperature for 1 hour. After the dough has risen, press it to a thickness of about 0.5 cm, and use a mold to make a number of dough cakes with a diameter of 5.7 cm.

[0067] Table 4 Basic formula of oil cake

[0068]

[0069] (3) Coat the surface of the dough with the prepared 1.0% sodium carboxymethyl cellulose batter to a thickness of about 0.2 cm, place it at room temperature for 1 hour to dry, and use the uncoated sample as the control group, fry it in edible oil at 185°C for 2 minutes, remove it, drain the oil, and cool it for 10 minutes to obtain the oil cake sample to be tested.

[0070] The malondialdehyde content in the fried noodle product of the comparative example was measured in the same manner as in Example 1.

[0071] Test results: The fried noodle products prepared in the comparative example had an increased fat content due to the shedding of the batter liquid and the disintegration of the batter film during the high-temperature frying process, and the poor barrier effect led to internal frying oxidation. Although the MDA content in the fat in the fried noodle products was also reduced, the degree of reduction was not high, from 0.63±0.01μg / g oil sample of the unbattered noodle product to 0.55±0.01μg / g oil sample, a decrease of 12.70%.

[0072] Table 5 The reduction of MDA in different battering liquids during frying of noodle products

[0073]

[0074]

[0075] It can be seen from Table 5 that fried noodle products coated with methylcellulose can effectively reduce the MDA produced during the frying process of fried noodle products. Compared with the same concentration of carboxymethyl cellulose coating liquid, the degree of reduction of MDA by methylcellulose coating liquid is significantly better. When the concentration of methylcellulose coating liquid is within the range of 1.0% to 1.5%, as the concentration of coating liquid increases, the degree of reduction of MDA in fried noodle products is greater, but the concentration of coating liquid should not be further increased, otherwise, due to its increased viscosity, it will increase the difficulty of coating and cause uneven coating, and it will also deepen the color of the noodle products and cause their sensory quality to decline.

[0076] The above embodiments are only preferred implementation modes of the present invention and are only used to explain the present invention rather than to limit the present invention. Any changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for reducing malondialdehyde in fried noodle products by coating with methylcellulose, characterized in that: The following steps are involved: (1) Add glycerin to hot water at a temperature of 70 to 80° C., add methyl cellulose while stirring, and then add ice water. After all the methyl cellulose is dissolved, a methyl cellulose paste is obtained, which is placed in a refrigerator for later use; (2) weighing flour, salt, and leavening agent into a dough mixer, mixing well, adding hot water at a temperature of 50 to 55° C., and kneading until the dough is smooth and not sticky, taking out the dough, and letting the dough rise at room temperature. After the dough has risen, pressing the dough into a dough product blank; (3) coating the surface of the noodle product blank of step (2) with the methyl cellulose coating liquid prepared in step (1), leaving it at room temperature to dry, and then frying it in an oil pan, taking it out, draining the oil, and cooling it to obtain a methyl cellulose coated fried noodle product.

2. The method for reducing malondialdehyde in fried noodle products by coating with methylcellulose according to claim 1, characterized in that: In step (1), the mass ratio of methyl cellulose, glycerol, hot water and ice water is 1-3:6:70:

130.

3. The method for reducing malondialdehyde in fried noodle products by coating with methylcellulose according to claim 1, characterized in that: In step (1), the concentration of the methylcellulose coating solution is 1.0% to 1.5%.

4. The method for reducing malondialdehyde in fried noodle products by coating with methylcellulose according to claim 1, characterized in that: In step (2), by weight: 90-100 parts flour 1.35-1.5 parts salt 2.7-3 parts of leavening agent 50-55 parts water The leavening agent is an aluminum-free leavening agent.

5. The method for reducing malondialdehyde in fried noodle products by coating with methylcellulose according to claim 1, characterized in that: In step (3), the specific operation of coating is: evenly coating the surface of the dough product with a layer of methyl cellulose coating liquid with a thickness of 0.2 to 0.3 cm, and drying it at room temperature.

6. The method of reducing malondialdehyde in fried noodle products by coating with methylcellulose according to claim 1, characterized in that: In step (3), the oil used in the frying process is vegetable oil or animal oil.

7. The method for reducing malondialdehyde in fried noodle products by coating with methylcellulose according to claim 1, characterized in that: In step (3), the frying temperature is 180-185° C., and the frying time is 2-4 min.

8. The method of reducing malondialdehyde in fried noodle products by coating with methylcellulose according to claim 1, characterized in that: Compared with unbattered noodle products, the MDA content of the methylcellulose battered fried noodle products is reduced by no less than 20%.

9. A battering material for reducing malondialdehyde in fried noodle products, characterized in that: The coating material is the methylcellulose coating liquid according to claim 1, the concentration of the methylcellulose coating liquid is 1.0% to 1.5%, and after coating, the methylcellulose accounts for no more than 1% of the total weight of the food.

10. A fried noodle product coated with methylcellulose prepared by the method according to any one of claims 1 to 9.

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