Biopreservative, method of preparation and use thereof in bakery products

Abstract

The present application belongs to the technical field of food processing, and particularly relates to a biological preservative, a preparation method thereof and application of the biological preservative in baked foods. In view of the poor dispersibility of natamycin in aqueous solution and the poor high-temperature resistance of the biological preservative, the present application first uses supercritical CO2 fluid to prepare soluble soybean polysaccharide microparticles which are small and have uniform particle size distribution, and then uses the microparticles and cotton oligosaccharides to form a double-layer interfacial film on the surface of the natamycin, thereby significantly improving the dispersibility of the natamycin in the biological preservative and greatly improving the high-temperature resistance of the biological preservative. The biological preservative prepared by the present application can be applied to baked foods, and can be sprayed on the surface of the baked foods immediately after baking, thereby effectively prolonging the shelf life of the baked foods at room temperature.

Description

Technical Field

[0001] This invention belongs to the field of food processing, specifically relating to a biological preservative, its preparation method, and its application in baked goods. Background Technology

[0002] Natamycin, also known as natamycin or streptomycin, is a polyene macrolide antifungal agent produced by the fermentation of Streptomyces. It has a broad-spectrum and highly effective inhibitory and bactericidal effect on fungi (molds and yeasts) and is the only internationally approved antifungal biological preservative. In my country's food additive standards, it has been classified as a natural food preservative and can be formulated into suspensions for spraying or soaking in various foods such as meat products, fried foods, and pastries. However, natamycin can only withstand short-term treatment at 100°C. Its solutions and suspensions are easily oxidized and deactivated, and high temperatures of 100°C and above will accelerate its deactivation. Therefore, when using it for the preservation of heat-processed foods, especially baked goods, it is generally sprayed onto the product surface after the product has cooled. However, the product is still susceptible to microbial contamination during the cooling process. Furthermore, natamycin has extremely poor dispersibility in water, is almost insoluble in water, and easily precipitates. Spraying or soaking methods are difficult to achieve a uniform coating on the product surface, thus reducing the preservative effect. Summary of the Invention

[0003] Based on the above reasons, the first objective of this invention is to provide a method for preparing a biological preservative, which utilizes soluble soybean polysaccharide microparticles and cottonseed oligosaccharides to form a double-layer interfacial film on the surface of natamycin, thereby significantly improving the dispersibility of natamycin in the biological preservative, while ensuring that the biological preservative still has a good preservative effect at high temperatures.

[0004] A second object of the present invention is to provide a biological preservative prepared according to the above preparation method.

[0005] A third objective of this invention is to provide the application of the above-mentioned biological preservatives in baked goods.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a biological preservative, comprising:

[0007] Natamycin was mixed with water, and soluble soybean polysaccharide microparticles were added and homogenized under high pressure to obtain a first solution; cottonseed oligosaccharide was added to the first solution and homogenized under low pressure.

[0008] The method for preparing the soluble soybean polysaccharide microparticles is as follows: soluble soybean polysaccharide is added to supercritical CO2 fluid, and the pressure is rapidly reduced after static reaction.

[0009] Preferably, the temperature of the supercritical CO2 fluid is 40-45°C and the pressure is 15-18 MPa.

[0010] Preferably, the mass fraction of the natamycin is 0.2%-0.6%.

[0011] Preferably, the mass fraction of the soluble soybean polysaccharide microparticles is 1%-3%.

[0012] Preferably, the mass fraction of the cottonseed oligosaccharide is 2%-4%.

[0013] Preferably, the high-pressure homogenization treatment is performed at a pressure of 120-140 MPa for 3-5 min; the low-pressure homogenization treatment is performed at a pressure of 20-30 MPa for 3-5 min.

[0014] Secondly, the present invention provides a biological preservative, which is prepared by any of the aforementioned methods for preparing biological preservatives.

[0015] Thirdly, the present invention provides the application of the aforementioned biological preservatives in baked goods.

[0016] Preferably, the biological preservative is sprayed onto the surface of the baked goods immediately after baking.

[0017] Preferably, the amount of the biological preservative sprayed is 0.3%-0.6% of the weight of the baked food.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) In view of the problem that existing natamycin has poor dispersibility and is not resistant to high temperature in aqueous solution, the present invention firstly uses supercritical CO2 fluid to prepare tiny, uniformly sized soluble soybean polysaccharide microparticles, and then uses high pressure homogenization to make the microparticles uniformly adhere to the surface of natamycin to form a first interfacial film. Then, under low pressure homogenization, cottonseed oligosaccharides form a second interfacial film on the surface of natamycin, so as to improve the dispersibility of natamycin in biological preservatives and significantly improve the high temperature resistance of biological preservatives.

[0020] (2) Due to the presence of a double-layer interfacial film, the biopreservative of the present invention allows for uniform dispersion of natamycin and maintains good preservative effect after short-term treatment at 180℃-190℃. In addition, the soluble soybean polysaccharides and cottonseed oligosaccharides used exhibit very low Maillard reaction, resulting in minimal impact on food quality.

[0021] (3) The biological preservative of the present invention can be applied to the preparation of baked goods and can be sprayed directly onto the surface of baked goods after baking, which can effectively extend the shelf life of baked goods at room temperature. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the following detailed description of the invention is provided in conjunction with embodiments. Those skilled in the art will understand that the following embodiments are merely exemplary and not intended to limit the scope of the invention. Furthermore, in the following description, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0023] First, it should be noted that current technology generally involves preparing natamycin into a suspension using water, and then applying it to the food surface via spraying or immersion to achieve a preservative effect. However, natamycin can only withstand brief treatment at 100°C. Its bacterial suspension is easily oxidized and deactivated, and the deactivation rate is significantly accelerated at high temperatures. In addition, natamycin has extremely poor dispersibility in water, is almost insoluble in water, and easily precipitates. In practical applications, it is difficult to coat it evenly on the food surface, thus reducing its preservative effect.

[0024] In view of this, the first embodiment of the present invention provides a method for preparing a biological preservative, comprising:

[0025] Natamycin was mixed with water, and soluble soybean polysaccharide microparticles were added and homogenized under high pressure to obtain a first solution; cottonseed oligosaccharide was added to the first solution and homogenized under low pressure.

[0026] The method for preparing the soluble soybean polysaccharide microparticles is as follows: soluble soybean polysaccharide is added to supercritical CO2 fluid, and the pressure is rapidly reduced after static reaction.

[0027] In this embodiment, the purpose of adding soluble soybean polysaccharide microparticles is to improve the dispersibility of natamycin in the biopreservative. Soluble soybean polysaccharides have good dispersibility and adhesion. After adhering to the surface of natamycin to form an interfacial film, they can effectively improve the dispersibility of natamycin in aqueous solution. However, their particle size is relatively large, making it difficult to directly form a dense interfacial film on the surface of natamycin. Existing technologies generally use ultrafine grinding to reduce particle size, but soluble soybean polysaccharides are prone to agglomeration during grinding, which leads to uneven particle size distribution. Through long-term research, the applicant has discovered that using supercritical solution rapid expansion technology, i.e., using supercritical CO2 fluid, soluble soybean polysaccharide microparticles with a particle size in the range of 30-45 μm and a uniform particle size distribution can be prepared. These microparticles can uniformly adhere to the surface of natamycin under high-pressure homogenization to form a first interfacial film, thereby greatly improving the dispersibility of natamycin in the prepared initial biopreservative.

[0028] It should be noted that since the decomposition temperature of soluble soybean polysaccharides is 60℃-80℃, the aforementioned initial biological preservative is still easily deactivated at high temperatures of 100℃ and above. Therefore, in this embodiment, cottonseed oligosaccharides are further added to the aforementioned initial biological preservative, which adhere to the surface of natamycin under low-pressure homogenization to form a second interfacial film, thereby significantly improving the high-temperature resistance of the final biological preservative, which maintains a good preservative effect after treatment at 180℃-190℃ for 30-240 s.

[0029] It should be noted that in this embodiment, the order of adding soluble soybean polysaccharide and cottonseed oligosaccharide cannot be changed. If cottonseed oligosaccharide is added first and then soluble soybean polysaccharide is added, natamycin in the prepared biological preservative will still be uniformly dispersed, but its high-temperature resistance will be only slightly improved.

[0030] In a specific embodiment, the temperature of the supercritical CO2 fluid is 40-45℃, the pressure is 15-18 MPa, and the static reaction time is 10-15 s. Under these conditions, the soluble soybean polysaccharide microparticles prepared have a small average particle size and uniform particle size distribution.

[0031] In a specific embodiment, the mass fraction of natamycin is 0.2%-0.6%, the mass fraction of soluble soybean polysaccharide microparticles is 1%-3%, and the mass fraction of cottonseed oligosaccharide is 2%-4%, to ensure the formation of a bilayer interfacial film.

[0032] In a specific implementation, the high-pressure homogenization treatment is carried out at a pressure of 120-140 MPa for 3-5 minutes; the low-pressure homogenization treatment is carried out at a pressure of 20-30 MPa for 3-5 minutes. It should be noted that the purpose of the high-pressure homogenization treatment is to ensure that the soluble soybean polysaccharide microparticles adhere uniformly to the surface of natamycin, forming a dense first interfacial film. The high-pressure homogenization treatment is followed by a settling period of 5-8 minutes to ensure the formation of the first interfacial film. The purpose of the low-pressure homogenization treatment is to ensure the integrity of the first interfacial film while simultaneously allowing cottonseed oligosaccharides to form a second interfacial film on the surface of natamycin.

[0033] The second embodiment of the present invention provides a biological preservative prepared according to the above preparation method. Compared with the traditional suspension prepared by directly dissolving natamycin in water, the biological preservative of the present invention exhibits uniform dispersion of natamycin, and its high-temperature resistance is significantly improved. It maintains a good preservative effect after treatment at 180℃-190℃ for 30-240 s. Furthermore, the soluble soybean polysaccharides and cottonseed oligosaccharides used exhibit a very low degree of Maillard reaction, resulting in minimal impact on food quality.

[0034] It should be noted that the biopreservative of this invention requires a short-term high-temperature treatment at 180℃-190℃ for 30-240 seconds during use. This is because cottonseed oligosaccharides only decompose above 180℃. After the above-mentioned high-temperature treatment, the second interfacial film formed by cottonseed oligosaccharides on the surface of natamycin gradually decomposes into melibiose and fructose. Subsequently, the fructose further decomposes, exposing natamycin and exerting its preservative effect. It is important to note that if the treatment temperature is below 180℃, the second interfacial film cannot decompose, and natamycin cannot exert its preservative effect; if the treatment temperature is above 190℃, the fructose will decompose prematurely at the higher temperature, exposing natamycin, which will be affected by the high temperature, thus reducing the preservative effect.

[0035] The third embodiment of the present invention provides the application of the above-mentioned biological preservative in baked goods. The baked goods include cakes, bread, biscuits, etc. The biological preservative is sprayed onto the surface of the baked goods immediately after baking, enabling the baked goods to have a shelf life of 11-13 days at room temperature.

[0036] It should be noted that the baking temperature of the baked goods should be 185℃-195℃ to maximize the preservative effect of natamycin in the biological preservative.

[0037] In a specific implementation, the amount of the biological preservative sprayed is 0.3%-0.6% of the weight of the baked food.

[0038] The following will disclose specific embodiments for implementing the present invention, as well as corresponding comparative examples to demonstrate the relevant technical effects of the present invention.

[0039] Example 1: Preparation of a biological preservative

[0040] Soluble soybean polysaccharides were added to a supercritical CO2 fluid and allowed to react statically for 12 seconds before being rapidly depressurized to obtain soluble soybean polysaccharide microparticles. The temperature of the supercritical CO2 fluid was 42°C and the pressure was 17 MPa.

[0041] Natamycin was mixed with water, and the above-mentioned soluble soybean microparticles were added. The mixture was then homogenized under high pressure at 130 MPa for 4 min. After standing for 7 min, cottonseed oligosaccharides were added and homogenized under low pressure at 25 MPa for 4 min to obtain a biological preservative. The mass fractions of natamycin, soluble soybean polysaccharide microparticles, and cottonseed oligosaccharides in the biological preservative were 0.4%, 2%, and 3%, respectively.

[0042] Example 2 Preparation of biological preservative

[0043] Soluble soybean polysaccharides were added to a supercritical CO2 fluid and reacted statically for 15 seconds, followed by rapid depressurization to obtain soluble soybean polysaccharide microparticles. The temperature of the supercritical CO2 fluid was 40°C and the pressure was 15 MPa.

[0044] Natamycin was mixed with water, and the above-mentioned soluble soybean microparticles were added. The mixture was then homogenized under high pressure at 140 MPa for 3 min. After standing for 8 min, cottonseed oligosaccharides were added and homogenized under low pressure at 30 MPa for 3 min to obtain a biological preservative. The mass fractions of natamycin, soluble soybean polysaccharide microparticles, and cottonseed oligosaccharides in the biological preservative were 0.2%, 1%, and 2%, respectively.

[0045] Example 3 Preparation of biological preservatives

[0046] Soluble soybean polysaccharides were added to a supercritical CO2 fluid and reacted statically for 10 seconds, followed by rapid depressurization to obtain soluble soybean polysaccharide microparticles. The temperature of the supercritical CO2 fluid was 45°C and the pressure was 18 MPa.

[0047] Natamycin was mixed with water, and the above-mentioned soluble soybean microparticles were added. The mixture was then homogenized under high pressure at 120 MPa for 5 min. After standing for 5 min, cottonseed oligosaccharides were added and homogenized under low pressure at 20 MPa for 5 min to obtain a biological preservative. The mass fractions of natamycin, soluble soybean polysaccharide microparticles, and cottonseed oligosaccharides in the biological preservative were 0.6%, 3%, and 4%, respectively.

[0048] Comparative Example 1: Preparation of a biological preservative

[0049] Natamycin is prepared by mixing it with water, wherein the mass fraction of natamycin is 0.4%.

[0050] Comparative Example 2: Preparation of a biological preservative

[0051] The preparation method is the same as in Example 1, except that the soluble soybean polysaccharide microparticles in Comparative Example 2 are prepared by ultrafine grinding, so that the particle size is in the range of 30-45 μm.

[0052] Comparative Example 3: Preparation of a biological preservative

[0053] The preparation method is the same as in Example 1, except that no soluble soybean polysaccharide microparticles are added in Comparative Example 3. Natamycin is directly mixed with water to obtain the first solution, and then cottonseed oligosaccharide is added for treatment.

[0054] Comparative Example 4: Preparation of a biological preservative

[0055] The preparation method is the same as in Example 1, except that no cottonseed oligosaccharides are added in Comparative Example 4, and the first solution is the biological preservative.

[0056] Comparative Example 5: Preparation of a biological preservative

[0057] The preparation method is the same as in Example 1, except that the order of adding soluble soybean polysaccharide microparticles and cottonseed oligosaccharides is changed in Comparative Example 5.

[0058] Comparative Example 6: Preparation of a biological preservative

[0059] The preparation method is the same as in Example 1, except that the static treatment is omitted in Comparative Example 6.

[0060] Comparative Example 7: Preparation of a biological preservative

[0061] The preparation method is the same as in Example 1, except that in Comparative Example 7, the low-pressure homogenization treatment is replaced with a high-pressure homogenization treatment, wherein the pressure of the high-pressure homogenization treatment is 130 MPa and the time is 4 min.

[0062] Experimental Example 1: Dispersibility Test of Natamycin in Biological Preservatives

[0063] The biological preservatives of Examples 1-3 and Comparative Examples 1-7 were left to stand at room temperature for 1 hour, and the precipitation phenomenon was observed and recorded. "-" indicates no precipitation or very little precipitation; "+" indicates a small amount of precipitation; and "++" indicates a large amount of precipitation. The test results are shown in Table 1.

[0064] Table 1. Dispersibility test results of biological preservatives

[0065] .

[0066] As shown in Table 1, the natamycin-containing biopreservative prepared using traditional methods (Comparative Example 1) is prone to precipitation. Only by utilizing the soluble soybean polysaccharide microparticles described in this invention to form a dense interfacial film on the surface of natamycin can the dispersibility of natamycin in the biopreservative be greatly improved (Examples 1-3 and Comparative Examples 4 and 5). In Comparative Example 2, the soluble soybean polysaccharide microparticles prepared using ultrafine grinding technology had an uneven particle size distribution, resulting in a poor improvement in natamycin dispersibility. Comparative Example 3, which only used cottonseed oligosaccharides, also showed a poor effect on improving natamycin dispersibility. In Comparative Examples 6-7, the interfacial film formed by the soluble soybean polysaccharide microparticles was damaged, resulting in poor natamycin dispersibility.

[0067] Experimental Example 2: High-Temperature Resistance Test of Biological Preservatives

[0068] Because natamycin has a good inhibitory effect on mold and yeast, and the surface of cake is very susceptible to mold infection and spoilage, after the cake is baked and cooled, it is sealed in aseptic packaging bags and stored at room temperature. The mold colony count will exceed the standard on the 4th day (GB 7099-2015 "National Food Safety Standard for Pastries and Bread" stipulates that the mold colony count of pastries should be ≤150 CFU / g). Therefore, in this experiment, the biological preservatives of Examples 1-3 and Comparative Examples 1-7 were first placed in an oven and treated at 180℃ for 30 s and 240 s, and at 190℃ for 30 s and 240 s, respectively. Then, sponge cakes were prepared according to the method in GB / T 24303-2009 "Grain and Oil Inspection: Test of Baking Quality of Wheat Flour Cakes - Sponge Cake Method". After the cakes cooled, the aforementioned biological preservatives were sprayed onto their surface, sealed in aseptic bags, and stored at room temperature (25℃). Following the method specified in GB4789.15-2016 "National Food Safety Standard: Microbiological Examination of Food - Molds and Yeasts", samples were taken daily during the cake storage period to detect mold colony counts. The number of days the mold colony count exceeded the standard was recorded, which is the shelf life of the cake. The high-temperature resistance of the biological preservative was then analyzed. Cakes without preservative treatment served as the control group. The test results are shown in Table 2. "Treatment 1" means that the biological preservative was treated at 180℃ for 30 s, "Treatment 2" means that the biological preservative was treated at 180℃ for 240 s, "Treatment 3" means that the biological preservative was treated at 190℃ for 30 s, and "Treatment 4" means that the biological preservative was treated at 190℃ for 240 s.

[0069] Table 2. Shelf life test results of cakes under different treatment conditions

[0070] .

[0071] As shown in Table 2, the high-temperature resistance of the biological preservative prepared in this invention is significantly improved. Compared with Example 1, the traditional natamycin preservative in Comparative Example 1 is inactivated under high-temperature treatment and cannot play a preservative role; in Comparative Examples 3 and 4, the cottonseed oligosaccharides and soluble soybean polysaccharides decompose at high temperatures of 180°C and above, thus failing to improve the high-temperature resistance of the biological preservative and also failing to play a preservative role; in Comparative Examples 2 and 5-8, the double-layer interfacial film formed on the surface of natamycin is not dense or is damaged to a certain extent, thus natamycin is affected by high temperatures to a certain extent, and the preservative effect is lower than that of Example 1.

[0072] Example 4: Preparation of Baked Goods

[0073] Sponge cakes were prepared according to the method in GB / T 24303-2009 "Grain and Oil Inspection: Test of Baking Quality of Wheat Flour Cakes - Sponge Cake Method". During the preparation process, a rotary oven was used for baking at a temperature of 185°C. After baking, the biological preservative from Example 1 was sprayed directly onto the cake surface at a spraying amount of 0.5% of the cake's mass.

[0074] After the cakes have cooled, they should be sealed in aseptic bags and stored at room temperature (25°C) for 13 days.

[0075] Example 5: Preparation of Baked Goods

[0076] Sponge cakes were prepared according to the method in GB / T 24303-2009 "Grain and Oil Inspection: Test of Baking Quality of Wheat Flour Cakes - Sponge Cake Method". During the preparation process, a rotary oven was used for baking at a temperature of 190°C. After baking, the biological preservative from Example 2 was sprayed directly onto the cake surface at a spraying amount of 0.3% of the cake's mass.

[0077] After the cakes have cooled, they should be sealed in aseptic bags and stored at room temperature (25°C) for 11 days.

[0078] Example 6: Preparation of Baked Goods

[0079] Sponge cakes were prepared according to the method in GB / T 24303-2009 "Grain and Oil Inspection: Test of Baking Quality of Wheat Flour Cakes - Sponge Cake Method". During the preparation process, a rotary oven was used for baking at a temperature of 195°C. After baking, the biological preservative from Example 3 was sprayed directly onto the cake surface at a spraying amount of 0.6% of the cake's mass.

[0080] After the cakes have cooled, they should be sealed in aseptic bags and stored at room temperature (25°C) for 12 days.

[0081] Comparative Example 8: Preparation of Baked Goods

[0082] The preparation method is the same as in Example 4, except that Comparative Example 8 uses the biological preservative of Comparative Example 1.

[0083] After cooling, the cakes from Comparative Example 8 were sealed in aseptic packaging bags and stored at room temperature (25°C) for 4 days.

[0084] Comparative Example 9: Preparation of Baked Goods

[0085] The preparation method is the same as in Example 4, except that in Comparative Example 9, the biological preservative is sprayed on after the cake has been baked and cooled.

[0086] The cake from Comparative Example 9 was sealed in an aseptic bag and stored at room temperature (25℃) for 4 days.

[0087] Comparative Example 10: Preparation of Baked Goods

[0088] The preparation method is the same as in Example 4, except that the baking temperature of the cake in Comparative Example 10 is 180°C.

[0089] The cakes from Comparative Example 10 were sealed in aseptic packaging bags and stored at room temperature (25℃) for 4 days.

[0090] Comparative Example 11: Preparation of Baked Goods

[0091] The preparation method is the same as in Example 4, except that the baking temperature of the cake in Comparative Example 11 is 200°C.

[0092] The cake from Comparative Example 11 was sealed in an aseptic bag and stored at room temperature (25°C) for 8 days.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a biological preservative, characterized in that, include: Natamycin was mixed with water, and soluble soybean polysaccharide microparticles were added. The mixture was then homogenized under high pressure to obtain the first solution. Cottonseed oligosaccharides were added to the first solution, and the mixture was homogenized under low pressure. The method for preparing the soluble soybean polysaccharide microparticles is as follows: soluble soybean polysaccharide is added to supercritical CO2 fluid, and the pressure is rapidly reduced after static reaction; the temperature of the supercritical CO2 fluid is 40-45℃ and the pressure is 15-18 MPa. The high-pressure homogenization process is carried out at a pressure of 120-140 MPa for 3-5 min; the low-pressure homogenization process is carried out at a pressure of 20-30 MPa for 3-5 min. The mass fractions of natamycin, soluble soybean polysaccharide microparticles, and cottonseed oligosaccharides are 0.2%-0.6%, 1%-3%, and 2%-4%, respectively.

2. The biological preservative prepared by the method described in claim 1.

3. The application of the biological preservative as described in claim 2 in baked goods.

4. The application as described in claim 3, characterized in that, The biological preservative is sprayed onto the surface of the food immediately after baking.

5. The application as described in claim 4, characterized in that, The amount of the biological preservative applied is 0.3%-0.6% of the weight of the baked goods.