Natural antioxidant, preparation method thereof and application of natural antioxidant in instant food

Abstract

The invention discloses a natural antioxidant which is prepared by mixing clove, rosemary and galangal according to the mass ratio of (1-9): (1-9): (1-9), and the antioxidant capacity of the natural antioxidant is 350-600 mg TE / g. The invention also discloses a preparation method of the natural antioxidant and an application of the natural antioxidant in instant food, especially an application of the natural antioxidant in instant beef balls. According to the natural antioxidant, the preparation method thereof and the application of the natural antioxidant in the instant food, a ball milling method is combined for extracting antioxidant active substances of natural spices, so that the extraction efficiency is greatly improved, the structure and activity of the antioxidant active substances are better reserved, and the antioxidant capacity of the antioxidant active substances is further enhanced; meanwhile, compared with a mode of single extraction and then compounding, the mixed extraction process disclosed by the invention is simpler and more convenient in process flow, reduces operation steps and time cost, and is more suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of food additives, and in particular relates to a natural antioxidant, a preparation method thereof, and application thereof in ready-to-eat foods. Background Art

[0002] Ready-to-eat food refers to a type of food that does not require additional processing and can be eaten directly after opening the package (or in bulk). In addition to various snacks, meat-based ready-to-eat foods are also popular because they meet the needs of modern fast-paced lifestyles. Chaoshan beef balls are a well-known specialty food that is loved and praised by consumers around the world. However, at present, their promotion is mainly in the form of quick-frozen products, which require secondary processing when eaten, and are difficult to meet the needs of modern fast-paced lifestyles. In order to increase its promotion, easy-to-carry ready-to-eat beef balls have appeared on the market. However, ready-to-eat beef balls are rich in nutrients such as fat and protein. During storage and sales, lipid oxidation and protein oxidation reactions are very likely to occur, which leads to problems such as damage to meat flavor and taste, loss of nutrients, and shortened shelf life. At present, the main antioxidant methods for ready-to-eat meat products are to add synthetic antioxidants and natural antioxidants. Although synthetic antioxidants (such as butylated hydroxyanisole (BHA)) have high stability and strong antioxidant capacity, long-term intake may pose potential risks to human health. Natural antioxidants are usually extracted from natural plants, animals or microorganisms. They not only have antioxidant properties, but also can give food a special aroma and improve the sensory quality of food.

[0003] Many natural spice extracts have antioxidant capacity and can add unique flavor and aroma to food, with the dual effects of seasoning and antioxidant. However, the existing natural spice antioxidant extraction method often uses a grinder to grind the raw materials into powder for extraction. However, a large amount of heat is generated during the grinding process, causing some phenolic active substances to change and reduce biological activity. At the same time, due to the large particle size after grinding, some materials cannot fully contact with the solvent, resulting in incomplete extraction and poor extraction effect. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a natural antioxidant with high efficiency and strong antioxidant activity, a preparation method thereof and its application in ready-to-eat foods. The strong antioxidant effect of the natural antioxidant is proved by measuring protein oxidation and lipid oxidation indicators, and it has broad application prospects in the ready-to-eat food industry.

[0005] The technical solution of the present invention to solve the above technical problems is: A natural antioxidant is prepared by mixing cloves, rosemary and galangal in a mass ratio of 1-9:1-9:1-9, and the antioxidant capacity of the natural antioxidant is 350-600 mg TE / g. Clove extract contains eugenol and eugenol acetate, and rosemary extract contains several terpene phenolic compounds such as carnosic acid, diterpenes and rosmarinus diphenol, which can interrupt the chain reaction of unsaturated fatty acids by providing hydrogen, isolate polyunsaturated fatty acids from oxygen free radicals, and thus achieve anti-fat oxidation function; galangal, as a spice and food widely used in Chaoshan area, not only has a unique flavor, but also contains substances with antioxidant activity such as flavonoids and phenolic compounds, showing strong superoxide, anion scavenging activity, Fe 2+ The natural antioxidant prepared by combining chelating activity and reducing ability can enhance the stability of instant beef balls during storage, effectively slow down oxidative deterioration, improve food safety, and thus promote the healthy development of the instant beef balls industry.

[0006] The method for preparing the above-mentioned natural antioxidant of the present invention comprises the following steps: Prepare the ingredients. Wash cloves, rosemary and galangal with clean water and dry them for later use. Raw material processing: the washed cloves and rosemary are respectively ground into powder using a grinder, and then passed through a 100-mesh sieve to obtain clove powder and rosemary powder; the washed galangal is freeze-dried, ground into powder using a grinder, and then passed through a 100-mesh sieve to obtain galangal powder; Preparation: take clove powder, rosemary powder and galangal powder respectively in a mass ratio of 1-9:1-9:1-9, mix them evenly, add distilled water in a material-liquid ratio of 1:5-20, stir and mix to obtain a preparation liquid; Ball milling: introducing the prepared liquid into a planetary ball mill for grinding to obtain a ball milling liquid; Reflux filtration, add ethanol to the ball milling liquid, reflux, cool to room temperature, put it into a glass funnel for filtration to obtain a treated liquid; Concentrating under reduced pressure, concentrating the treated liquid under reduced pressure to obtain a concentrated solution; Freeze drying: placing the concentrated solution into a freeze dryer for freeze drying to obtain natural antioxidant powder.

[0007] Specifically, in the ball milling step, the grinding dish in the planetary ball mill is a nylon ball mill, the grinding balls are oxidized grinding stone balls, the grinding speed is 100~300 r / min, the ball-to-material ratio during the grinding process is 5~20% by mass, and the grinding time is 10~40 min.

[0008] Preferably, the reflux filtration step comprises: First reflux: add 5-20 times volume of food-grade anhydrous ethanol to the ball milling liquid, reflux at 30-60 °C for 1-4 h, cool to room temperature after reflux, and filter with a glass funnel to obtain the first reflux liquid and filter residue; Secondary reflux: mix the filter residue with 10-40 times the volume of 40-80% ethanol aqueous solution, reflux at 30-60 °C for 1-4 h, cool to room temperature after reflux, and filter with a glass funnel to obtain secondary reflux liquid; Collect and combine the primary reflux liquid and the secondary reflux liquid to obtain a treated liquid.

[0009] Specifically, in the pressurized concentration step, the pressure is -0.09 Mpa, the temperature is 45°C, and the concentration is to 15% of the original volume.

[0010] Specifically, in the freeze-drying step, the pressure is 5 Mpa, the temperature is -80°C, and the freeze-drying time is 48 h.

[0011] Preferably, the mass ratio of the clove powder, rosemary powder and galangal powder is 1-6:1-7:1-8.

[0012] The application of the natural antioxidant prepared by the present invention in ready-to-eat food is to use the natural antioxidant as mentioned above as an additive and add it into the ready-to-eat food.

[0013] Specifically, the instant food includes instant beef balls.

[0014] The present invention has the following beneficial effects: (1) Compared with the traditional pulverizer, the present invention combines the ball milling method to extract the antioxidant active substances from natural spices, which greatly improves the extraction efficiency, better preserves the structure and activity of the antioxidant active substances, and thus enhances their antioxidant capacity.

[0015] (2) In the preparation of natural antioxidants, the present invention extracts cloves, rosemary and galangal in a specific ratio, and its antioxidant effect is significantly better than that of natural antioxidants extracted separately and then compounded, indicating that a synergistic effect occurs between the active substances, which greatly improves the antioxidant performance. In addition, compared with the method of extracting separately and then compounding, the mixed extraction process of the present invention is simpler and more convenient, reduces the operation steps and time cost, and is more suitable for industrial large-scale production.

[0016] (3) The present invention applies the prepared natural antioxidant to the instant beef balls, which effectively delays the degree of lipid oxidation and protein oxidation, and is natural and non-toxic, which meets consumers' pursuit of healthy food. In addition, it can also give the instant beef balls a special aroma, further improve the sensory quality of the food, enhance the market competitiveness of the product, and effectively promote the healthy development of the instant beef balls industry. DETAILED DESCRIPTION

[0017] In order to better understand the present invention, the following will specifically explain the determination of the free radical scavenging ability of the extract ABTS, the lipid oxidation determination and the protein oxidation determination experiment and further illustrate the present invention in conjunction with specific examples, but the embodiments of the present invention are not limited thereto. The raw materials and reagents used in the examples are all commercially available unless otherwise specified.

[0018] 1. Determination of the free radical scavenging ability of ABTS extract Prepare 0.1 mol / mL Trolox stock solution, take 0, 0.05, 0.10, 0.15, 0.20 mL Trolox stock solution, dilute to 1 mL with anhydrous ethanol, and obtain a series of Trolox standard solutions. Then add 4 mL of ABTS working solution, stand in dark for 5 minutes, and measure the absorbance at a wavelength of 734 nm to obtain the sample group A. 1 ; 4 mL buffer (50 mM, pH = 7.4) was used instead of ABTS working solution, and the absorbance value was measured as control group A 2 ; Anhydrous ethanol was used instead of Trolox standard solution, and the absorbance value was measured as blank group A 0 , the calculation method of ABTS free radical scavenging rate is shown in the formula. With Trolox mass concentration (mg / mL) as the horizontal axis and ABTS free radical scavenging rate as the vertical axis, draw the ABTS standard curve. The sample is measured according to the above method, and the obtained ABTS scavenging rate is substituted into the standard curve to calculate the Trolox equivalent of the natural spice extract solution.

[0019]

[0020] 2. Determination method of oil oxidation Weigh 5 g of meatballs, mince evenly, add 25 mL of 7.5% trichloroacetic acid solution containing 0.1% disodium ethylenediaminetetraacetate, homogenize for 10 min, filter, measure 5 mL of filtrate and mix evenly with 5 mL of 0.02 M thiobarbituric acid solution, place in a boiling water bath for 40 min, take out, cool to room temperature, centrifuge at 16000 rpm for 10 min, take out the supernatant, add 5 mL of chloroform and shake evenly, let stand for stratification, and measure the absorbance at wavelengths of 532 nm and 600 nm respectively. The calculation formula is as follows, where A532 represents the absorbance of the solution at a wavelength of 532 nm, A 600 represents the absorbance of the solution at a wavelength of 600 nm, 155 is the molar absorption coefficient, and 72.6 is the molar mass of malondialdehyde.

[0021]

[0022] 3. Protein oxidation determination method (1) Determination of protein carbonyl value Take 2 g of meatball sample, add 10 mL of 20 mM phosphate buffer (pH 6.5, containing 0.6 mol / L NaCl), homogenize, centrifuge at 13000 r / min, and take the supernatant as protein extract. Take 0.4 mL of protein extract, add 0.2 mL of 2M HCL (containing 10 mM 2,4-dinitrophenylhydrazine (DNPH)), and place in a light-proof water bath at 30 ℃ for 1 h. After the protein extract and DNPH are fully mixed, add 1 mL of 40% trichloroacetic acid to each tube to precipitate protein and let stand for 20 minutes. Centrifuge at 13000 r / min for 15 min and discard the supernatant. Wash the precipitate with 1 mL of ethyl acetate:ethanol (v / v=1:1) to remove the unreacted solvent, then centrifuge at 13000 r / min for 10 min, and repeat the above washing process until the supernatant is a colorless liquid after the sample is centrifuged. Then, 3 mL of 6 mol / L guanidine hydrochloride solution was used to dissolve the protein precipitate. After the precipitate was completely dissolved, the absorbance was measured at a wavelength of 370 nm. The results were expressed as nmoL carbonyl / mg protein. The protein content was determined by the biuret method, and bovine serum albumin was used as the standard curve. The calculation formula is as follows, where A represents the absorbance of the sample measured at 370 nm, C represents the protein concentration obtained by the BCA method (mg / mL), D represents the colorimetric light path (cm), and 22000 is the molar absorption coefficient (L / (moL∙cm)).

[0023]

[0024] (2) Determination of protein thiol value Weigh 2.0 g of meat sample and homogenize it in 10 mL of 50 mM phosphate buffer with a pH of 8.0. Centrifuge the homogenate and take the supernatant as the protein extract. Take 9.0 mL of 50 mM phosphate buffer with a pH of 8.0 and 1 mL of protein solution, mix them well, add 20 μL of 2 mmol / L 5,5-disulfide bis reagent to the protein sample, vortex and mix well, react at 25 °C in the dark for 1 hour, and then measure the absorbance at a wavelength of 412 nm. The results are expressed as nmol / mg protein. The protein content was determined by the biuret method, and bovine serum albumin was used as the standard curve. The calculation formula is as follows, where A represents the absorbance of the sample measured at 412 nm, C represents the protein concentration (mg / mL) obtained by the biuret method, D represents the colorimetric light path (cm), and 13600 is the molar absorption coefficient (L / (moL∙cm)).

[0025] Example 1

[0026] A natural antioxidant according to Example 1 of the present invention, wherein the preparation method thereof comprises the following steps: Prepare the ingredients. Wash the cloves, rosemary and galangal with clean water to remove impurities, then dry them and set aside.

[0027] Raw material processing: the washed cloves and rosemary are cut into small pieces, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain clove powder and rosemary powder; the washed galangal is cut into small pieces, freeze-dried to remove moisture, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain galangal powder.

[0028] Preparation: Take clove powder, rosemary powder and galangal powder in a mass ratio of 1:7:3, mix them evenly, add distilled water in a solid-liquid ratio (V / W) of 1:5, stir and mix to obtain a prepared solution.

[0029] Ball milling, introducing the prepared liquid into a planetary ball mill for grinding to obtain a ball milling liquid; specifically, the grinding dish in the planetary ball mill is a nylon ball milling jar, the grinding balls are oxidized grinding stone balls, the grinding speed is 200 r / min, the ball-to-material ratio during the grinding process is 10% by mass, the grinding time is 25 min, and the liquid collected after grinding is the ball milling liquid.

[0030] Reflux filtration, add 5 times the volume of food-grade anhydrous ethanol to the ball milling liquid, reflux at 50 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a primary reflux liquid and filter residue; mix the filter residue with 10 times the volume of 50% ethanol aqueous solution, reflux at 50 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a secondary reflux liquid; combine the primary reflux liquid and the secondary reflux liquid to obtain a treated liquid.

[0031] The treated liquid was concentrated under reduced pressure at a pressure of -0.09 MPa and a temperature of 45°C to 15% of the original volume to obtain a concentrated solution.

[0032] Freeze drying: the concentrate was placed in a freeze dryer and freeze-dried for 48 h at a pressure of 5 MPa and a temperature of -80 °C, and then the freeze-dried powder was collected to obtain a natural antioxidant powder, which was recorded as G1.

[0033] 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be minced into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 3 g of natural antioxidant powder (G1) were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into uniform-sized meatballs, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the finished instant beef meatballs, which were recorded as N1. Example 2

[0034] A natural antioxidant according to Example 2 of the present invention, wherein the preparation method thereof comprises the following steps: Prepare the ingredients. Wash the cloves, rosemary and galangal with clean water to remove impurities, then dry them and set aside.

[0035] Raw material processing: the washed cloves and rosemary are cut into small pieces, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain clove powder and rosemary powder; the washed galangal is cut into small pieces, freeze-dried to remove moisture, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain galangal powder.

[0036] Preparation: Take clove powder, rosemary powder and galangal powder in a mass ratio of 3:7:1 respectively, mix them evenly, add distilled water in a solid-liquid ratio (V / W) of 1:10, stir and mix to obtain a prepared solution.

[0037] Ball milling, introducing the prepared liquid into a planetary ball mill for grinding to obtain a ball milling liquid; specifically, the grinding dish in the planetary ball mill is a nylon ball milling jar, the grinding balls are oxidized grinding stone balls, the grinding speed is 250 r / min, the ball-to-material ratio during the grinding process is 12% by mass, the grinding time is 15 min, and the liquid collected after grinding is the ball milling liquid.

[0038] Reflux filtration, add 10 times the volume of food-grade anhydrous ethanol to the ball milling liquid, reflux at 60 ° C for 3 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a primary reflux liquid and filter residue; mix the filter residue with 20 times the volume of 50% ethanol aqueous solution, reflux at 60 ° C for 3 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a secondary reflux liquid; combine the primary reflux liquid and the secondary reflux liquid to obtain a treated liquid.

[0039] The treated liquid was concentrated under reduced pressure at a pressure of -0.09 MPa and a temperature of 45°C to 15% of the original volume to obtain a concentrated solution.

[0040] Freeze drying: the concentrate was placed in a freeze dryer and freeze-dried for 48 h at a pressure of 5 MPa and a temperature of -80 °C, and then the freeze-dried powder was collected to obtain a natural antioxidant powder, which was recorded as G2.

[0041] 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 3 g of natural antioxidant powder (G2) were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into uniform-sized meatballs, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the finished instant beef meatballs, which were recorded as N2. Example 3

[0042] A natural antioxidant according to Example 3 of the present invention, wherein the preparation method thereof comprises the following steps: Prepare the ingredients. Wash the cloves, rosemary and galangal with clean water to remove impurities, then dry them and set aside.

[0043] Raw material processing: the washed cloves and rosemary are cut into small pieces, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain clove powder and rosemary powder; the washed galangal is cut into small pieces, freeze-dried to remove moisture, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain galangal powder.

[0044] Preparation: Take clove powder, rosemary powder and galangal powder in a mass ratio of 5:5:1, mix them evenly, add distilled water in a solid-liquid ratio (V / W) of 1:7.5, stir and mix to obtain a prepared solution.

[0045] Ball milling, introducing the prepared liquid into a planetary ball mill for grinding to obtain a ball milling liquid; specifically, the grinding dish in the planetary ball mill is a nylon ball milling jar, the grinding balls are oxidized grinding stone balls, the grinding speed is 180 r / min, the ball-to-material ratio during the grinding process is 10% by mass, the grinding time is 35 min, and the liquid collected after grinding is the ball milling liquid.

[0046] Reflux filtration, add 7.5 times the volume of food-grade anhydrous ethanol to the ball milling liquid, reflux at 50 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a primary reflux liquid and filter residue; mix the filter residue with 15 times the volume of 50% ethanol aqueous solution, reflux at 50 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a secondary reflux liquid; combine the primary reflux liquid and the secondary reflux liquid to obtain a treated liquid.

[0047] The treated liquid was concentrated under reduced pressure at a pressure of -0.09 MPa and a temperature of 45°C to 15% of the original volume to obtain a concentrated solution.

[0048] Freeze drying: the concentrate was placed in a freeze dryer and freeze-dried for 48 h at a pressure of 5 MPa and a temperature of -80 °C, and then the freeze-dried powder was collected to obtain a natural antioxidant powder, which was recorded as G3.

[0049] 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 3 g of natural antioxidant powder (G3) were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into uniform-sized meatballs, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the ready-to-eat beef meatballs, which were recorded as N3. Example 4

[0050] A natural antioxidant according to Example 4 of the present invention, wherein the preparation method thereof comprises the following steps: Prepare the ingredients. Wash the cloves, rosemary and galangal with clean water to remove impurities, then dry them and set aside.

[0051] Raw material processing: the washed cloves and rosemary are cut into small pieces, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain clove powder and rosemary powder; the washed galangal is cut into small pieces, freeze-dried to remove moisture, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain galangal powder.

[0052] Preparation: Take clove powder, rosemary powder and galangal powder in a mass ratio of 6:1:4 respectively, mix them evenly, add distilled water in a solid-liquid ratio (V / W) of 1:5, stir and mix to obtain a prepared solution.

[0053] Ball milling, introducing the prepared liquid into a planetary ball mill for grinding to obtain a ball milling liquid; specifically, the grinding dish in the planetary ball mill is a nylon ball milling jar, the grinding balls are oxidized grinding stone balls, the grinding speed is 150 r / min, the ball-to-material ratio during the grinding process is 10% by mass, the grinding time is 40 min, and the liquid collected after grinding is the ball milling liquid.

[0054] Reflux filtration, add 5 times the volume of food-grade anhydrous ethanol to the ball milling liquid, reflux at 60 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a primary reflux liquid and filter residue; mix the filter residue with 10 times the volume of 50% ethanol aqueous solution, reflux at 60 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a secondary reflux liquid; combine the primary reflux liquid and the secondary reflux liquid to obtain a treated liquid.

[0055] The treated liquid was concentrated under reduced pressure at a pressure of -0.09 MPa and a temperature of 45°C to 15% of the original volume to obtain a concentrated solution.

[0056] Freeze drying: the concentrate was placed in a freeze dryer and freeze-dried for 48 h at a pressure of 5 MPa and a temperature of -80 °C, and then the freeze-dried powder was collected to obtain a natural antioxidant powder, which was recorded as G4.

[0057] 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 3 g of natural antioxidant powder (G4) were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into uniform-sized meatballs, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the ready-to-eat beef meatballs, which were recorded as N4. Example 5

[0058] A natural antioxidant according to Example 5 of the present invention, wherein the preparation method comprises the following steps: Prepare the ingredients. Wash the cloves, rosemary and galangal with clean water to remove impurities, then dry them and set aside.

[0059] Raw material processing: the washed cloves and rosemary are cut into small pieces, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain clove powder and rosemary powder; the washed galangal is cut into small pieces, freeze-dried to remove moisture, ground into powder by a grinder, and then passed through a 100-mesh sieve to obtain galangal powder.

[0060] Preparation: Take clove powder, rosemary powder and galangal powder in a mass ratio of 2:1:8 respectively, mix them evenly, add distilled water in a solid-liquid ratio (V / W) of 1:15, stir and mix to obtain a prepared solution.

[0061] Ball milling, introducing the prepared liquid into a planetary ball mill for grinding to obtain a ball milling liquid; specifically, the grinding dish in the planetary ball mill is a nylon ball milling jar, the grinding balls are oxidized grinding stone balls, the grinding speed is 150 r / min, the ball-to-material ratio during the grinding process is 10% by mass, the grinding time is 40 min, and the liquid collected after grinding is the ball milling liquid.

[0062] Reflux filtration, add 15 times the volume of food-grade anhydrous ethanol to the ball milling liquid, reflux at 60 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a primary reflux liquid and filter residue; mix the filter residue with 30 times the volume of 50% ethanol aqueous solution, reflux at 60 ° C for 2 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain a secondary reflux liquid; combine the primary reflux liquid and the secondary reflux liquid to obtain a treated liquid.

[0063] The treated liquid was concentrated under reduced pressure at a pressure of -0.09 MPa and a temperature of 45°C to 15% of the original volume to obtain a concentrated solution.

[0064] Freeze drying: the concentrate was placed in a freeze dryer and freeze-dried for 48 h at a pressure of 5 MPa and a temperature of -80 °C, and then the freeze-dried powder was collected to obtain a natural antioxidant powder, which was recorded as G5.

[0065] 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 3 g of natural antioxidant powder (G5) were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into uniform-sized meatballs, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the ready-to-eat beef meatballs, which were recorded as N5.

[0066] Comparative Example 1: 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, and 25 g of cornstarch were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into balls of uniform size, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the finished instant beef meatballs, which were recorded as N6.

[0067] Comparative Example 2: Wash and dry cloves, rosemary and galangal, cut cloves and rosemary into small pieces, grind them with a grinder, and pass the powder through a 100-mesh sieve; cut galangal into small pieces, freeze-dry to remove moisture, grind them with a grinder, and pass the powder through a 100-mesh sieve. Mix clove powder, rosemary powder and galangal powder in a mass ratio of 1:7:3, add a certain amount of distilled water according to a 5-fold volume (V / W) solid-liquid ratio, and add 5-fold food-grade anhydrous ethanol, reflux at 60 °C for 2 h, and filter the mixture with a glass funnel when it cools to room temperature. The residue is refluxed with 10-fold volume of ethanol aqueous solution (50%) under the same conditions, and then concentrated under reduced pressure and freeze-dried to obtain a natural antioxidant powder derived from spices, which is recorded as D2.

[0068] 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 3 g of natural antioxidant powder (D2) were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into uniform-sized meatballs, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the ready-to-eat beef meatballs, which were recorded as N7.

[0069] Comparative Example 3: Wash and dry cloves, rosemary and galangal. Cut cloves and rosemary into small pieces and grind them in a grinder. The powder is passed through a 100-mesh sieve. Cut galangal into small pieces and freeze-dry to remove moisture. Then grind them in a grinder and pass the powder through a 100-mesh sieve. Extract the active substances of clove powder, rosemary powder and galangal powder respectively, and add a certain amount of distilled water according to a 7.5-fold volume (V / W) ratio of liquid to liquid. Grind them in a planetary ball mill. Nylon ball mill and zirconium oxide grinding stone balls are used for grinding. The grinding conditions are a speed of 200 r / min, a ball-to-liquid ratio of 15% (mass ratio), and grinding for 35 min. Then, it was taken out and 7.5 times of food-grade anhydrous ethanol was added, and refluxed at 50 °C for 2 h. When the mixture was cooled to room temperature, it was filtered with a glass funnel, and the residue was refluxed again with 15 times the volume of ethanol aqueous solution (50%) under the same conditions, and then concentrated under reduced pressure and freeze-dried to obtain natural antioxidant powders from cloves, recorded as Q1; natural antioxidant powders from rosemary, recorded as Q2; and natural antioxidant powders from galangal, recorded as Q3. Q1, Q2 and Q3 were mixed in a ratio of 1:7:3 to obtain natural antioxidant powder, recorded as D3.

[0070] 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 3 g of natural antioxidant powder (D3) were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into uniform-sized meatballs, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the finished instant beef meatballs, which were recorded as N8.

[0071] Comparative Example 4: 1 kg of beef hind leg meat was selected, the fascia was removed, cut into strips and placed in a meat grinder to be crushed into strips of meat balls, and then placed in a meatball beater for pounding. After pounding for 5 minutes, 5 g of baking soda, 20 g of salt, 20 g of monosodium glutamate, 5 g of compound phosphate, 25 g of garlic crisps, 300 g of drinking water, 25 g of cornstarch, and 0.2 g of BHA were added. After pounding for 10 minutes, the machine was stopped to form a soft and sticky meatball material. Subsequently, the meatball material was kneaded into balls of uniform size, placed in 55 ℃ warm water for 10 minutes to solidify the surface of the meatballs, and then placed in 85 ℃ hot water for 6 minutes and then picked up. After cooling, vacuum packaging and sterilization were performed to obtain the finished instant beef meatballs, which were recorded as N9.

[0072] Next, the efficacy of the natural antioxidants and instant beef meatballs prepared in Examples 1-5 and Comparative Examples 1-4 was evaluated.

[0073] 1. Comparison of antioxidant capacity of natural antioxidants ABTS is an indicator for judging the free radical scavenging ability of a substance. The higher the value, the stronger the antioxidant ability. As can be seen from Table 1, compared with D2 (ethanol reflux extraction, supplemented by traditional crushing method, without ball milling), G1, G2, G3, G4 and G5 (ethanol reflux extraction, supplemented by traditional crushing method and ball milling) have stronger ABTS free radical scavenging ability, that is, stronger antioxidant ability, which indicates that the addition of ball milling method promotes the precipitation of antioxidant active substances in spices, improves the extraction effect, and enhances its antioxidant ability. Under the same compounding ratio and combined with ball milling extraction, there is a significant difference in the ABTS free radical scavenging ability of G1 (spice compound extraction) and D3 (spice single extraction and compounding), the ABTS value of G1 is 394 mgTE / g, and the ABTS value of D3 is 326 mg TE / g. Compared with D3, the ABTS value of G1 increased significantly by 20.86%, indicating that the mixed extraction of spices is better than that of single extraction and then compounding. This may be because some components in spices may promote the dissolution of antioxidants in other spices, making antioxidants that are difficult to dissolve in single extraction easier to dissolve in the solvent, thereby improving the overall extraction rate and antioxidant effect. At the same time, different spices contain different antioxidant components. In the process of mixed compound extraction, these components can cooperate with each other to jointly cope with the attack of free radicals, and ultimately improve the antioxidant effect. In addition, the difference in the mixed compound ratio will also significantly affect the antioxidant effect of the extracted antioxidants. It can be seen from Table 1 that among all the embodiment groups, G4 (clove: rosemary: galangal = 6: 1: 4) has the highest ABTS value, followed by G3 (clove: rosemary: galangal = 5: 5: 1), G2 (clove: rosemary: galangal = 3: 7: 1), G5 (clove: rosemary: galangal = 2: 1: 8) and G1 (clove: rosemary: galangal = 1: 7: 3), but they are all significantly higher than the ABTS values ​​of D2 and D3 in the comparative example.

[0074]

[0075] Note: The data in the table are all mean ± standard deviation. Different superscript letters in the same column indicate significant differences. （P<0.05） 2. Comparison of fat oxidation and protein oxidation in instant beef balls Thiobarbituric acid value (TBA) is an important indicator for measuring the degree of oil oxidation. The TBA value can intuitively reflect the degree of oil oxidation, that is, the higher the TBA value, the more malondialdehyde produced by oil oxidation, and the more serious the oil oxidation degree. As can be seen from Table 2, N6 (without adding antioxidant) has the highest TBA value, which is significantly higher than N1, N2, N3, N4, N5, N7 and N8, which shows that the natural antioxidant prepared by the present invention can effectively delay the oil oxidation degree of instant beef balls, and the TBA value of N7 is also significantly higher than N1, N2, N3, N4, N5, which shows that the natural antioxidant prepared by the present invention has a stronger antioxidant effect than the natural antioxidant prepared by the traditional pulverization method. Among them, N4 has the lowest TBA value of 0.2 mg / Kg, which is consistent with the antioxidant capacity results of the antioxidants in Table 1 above, that is, the antioxidant capacity of the antioxidant is positively correlated with the effect of delaying oil oxidation in instant beef balls. At the same time, compared with N9 (added with BHA), the TBA values ​​of N2, N3, N4, and N5 were significantly reduced, indicating that the antioxidant effect of the natural antioxidant prepared by the present invention is better than that of the synthetic antioxidant. The above shows that the antioxidant obtained by the present invention can be effectively applied to instant beef ball products.

[0076] The carbonyl content and thiol content can reflect the degree of protein oxidation in food. The carbonyl content can be used as a key indicator to measure the degree of protein oxidation. The higher the content, the more serious the protein oxidation. When detecting the degree of oxidation of instant beef balls, the degree of protein oxidation in the instant beef balls can be clearly understood by measuring its carbonyl content, and then the effect of natural antioxidants on delaying protein oxidation can be judged. In addition, during protein oxidation, thiol groups are easily oxidized to disulfide bonds (-SS-) or other oxidized forms, which leads to a decrease in thiol content. Therefore, the antioxidant effect of the natural antioxidant can be evaluated by detecting the change in its thiol content. As can be seen from Table 2, N6 (without antioxidant added) has the highest carbonyl content of 5.42 nmol / mg protein, which is significantly higher than other groups, indicating that the protein oxidation degree of N6 is the most serious; N6 has the lowest thiol content of 2.52 nmol / mg protein, which is significantly lower than other groups, indicating that its protein structure stability is the worst and the degree of oxidation is higher. Among all the groups, the instant beef balls made by the antioxidants extracted by ball milling and mixing have lower carbonyl content and higher sulfhydryl content, among which the N4 group has the lowest carbonyl content and the highest sulfhydryl content, which indicates that the protein oxidation degree of the instant beef balls made by the natural antioxidant G4 is the lowest. At the same time, compared with N9 (added with BHA), the sulfhydryl content of N2, N3, N4, and N5 increased significantly, and the carbonyl content decreased significantly, indicating that the antioxidant effect of the natural antioxidant prepared by the present invention is better than that of the synthetic antioxidant.

[0077]

[0078] Note: The data in the table are all mean ± standard deviation. Different superscript letters in the same column indicate significant differences. （P<0.05） In summary, the present invention provides a natural antioxidant and its preparation method and its application in ready-to-eat food. After the addition of the ball milling method, the dissolution of the antioxidant active substances in the spices is greatly improved, so that the antioxidant capacity of the extract is improved. The mixed compound (clove: rosemary: galangal = 6:1:4) provided by the present invention combined with the ball milling extraction method is more conducive to the dissolution of active substances, reduces losses, simplifies the extraction process steps, shortens the time cost, and can be effectively applied to ready-to-eat beef ball products, delaying the degree of oil oxidation and protein oxidation, extending the shelf life, and enhancing the safety of ready-to-eat meat products. At the same time, it has the potential to replace synthetic antioxidants in the ready-to-eat meat products industry.

[0079] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A natural antioxidant, characterized in that: The natural antioxidant is prepared by mixing cloves, rosemary and galangal in a mass ratio of 1-9:1-9:1-9. The antioxidant capacity of the natural antioxidant is 350-600 mg TE / g.

2. A method for preparing a natural antioxidant, characterized in that: The steps include: Prepare the ingredients. Wash cloves, rosemary and galangal with clean water and dry them for later use. Raw material processing: the washed cloves and rosemary are respectively ground into powder using a grinder, and then passed through a 100-mesh sieve to obtain clove powder and rosemary powder; the washed galangal is freeze-dried, ground into powder using a grinder, and then passed through a 100-mesh sieve to obtain galangal powder; Preparation: After uniformly mixing clove powder, rosemary powder and galangal powder in a mass ratio of 1-9:1-9:1-9, distilled water is added in a material-liquid ratio of 1:5-20, and the mixture is stirred to obtain a preparation solution; Ball milling: introducing the prepared liquid into a planetary ball mill for grinding to obtain a ball milling liquid; Reflux filtration, add ethanol to the ball milling liquid, reflux, cool to room temperature, put it into a glass funnel for filtration to obtain a treated liquid; Concentrating under reduced pressure, concentrating the treated liquid under reduced pressure to obtain a concentrated solution; Freeze drying: placing the concentrated solution into a freeze dryer for freeze drying to obtain natural antioxidant powder.

3. The method for preparing the natural antioxidant according to claim 2, characterized in that: In the ball milling step, the grinding dish in the planetary ball mill is a nylon ball mill, the grinding balls are oxidized grinding stone balls, the grinding speed is 100~300 r / min, the ball-to-material ratio during the grinding process is 5~20% by mass, and the grinding time is 10~40 min.

4. The method for preparing the natural antioxidant according to claim 2, characterized in that: The reflux filtration step comprises: First reflux: add 5-20 times volume of food-grade anhydrous ethanol to the ball milling liquid, reflux at 30-60 °C for 1-4 h, cool to room temperature after reflux, and filter with a glass funnel to obtain the first reflux liquid and filter residue; Secondary reflux: mix the filter residue with 10-40 times the volume of 40-80% ethanol aqueous solution, reflux at 30-60°C for 1-4 hours, cool to room temperature after reflux, and filter with a glass funnel to obtain secondary reflux liquid; Collect and combine the primary reflux liquid and the secondary reflux liquid to obtain a treated liquid.

5. The method for preparing the natural antioxidant according to claim 2, characterized in that: In the pressurized concentration step, the pressure is -0.09 Mpa, the temperature is 45°C, and the concentration is to 15% of the original volume.

6. The method for preparing the natural antioxidant according to claim 1, characterized in that: In the freeze-drying step, the pressure is 5 MPa, the temperature is -80°C, and the freeze-drying time is 48 h.

7. The method for preparing the natural antioxidant according to any one of claims 2 to 6, characterized in that: The mass ratio of the clove powder, rosemary powder and galangal powder is 1-6:1-7:1-8.

8. Use of a natural antioxidant in ready-to-eat food, characterized in that: The natural antioxidant as claimed in claim 1 is used as an additive to instant food.

9. The use of the natural antioxidant in ready-to-eat food according to claim 8, characterized in that: The instant food comprises instant beef meatballs.

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