阅读说明：本技术 一种橡子壳提取物涂膜保鲜剂及其制备方法 (Acorn shell extract coating preservative and preparation method thereof ) 是由 李德海 张博 包怡红 王泽童 王楚雅 王怡雪 禚宇 王荣芳 于 2020-11-23 设计创作，主要内容包括：一种橡子壳提取物涂膜保鲜剂及其制备方法,它涉及涂膜保鲜剂及其制备方法。本发明的目是提供一种橡子壳提取物涂膜保鲜剂及其制备方法。本发明的橡子壳提取物涂膜保鲜剂是由橡子壳提取物、橡实淀粉酯、壳聚糖、海藻酸钠、单甘酯和水制成的。制法：将橡实淀粉酯、壳聚糖、海藻酸钠、单甘酯加入到部分水中,得到混合液；再将橡子壳提取物加入到剩余的水中,混合均匀后倒入混合液中,再进行高速剪切处理,得到橡子壳提取物涂膜保鲜剂。它对大肠杆菌、金黄色葡萄球菌和的沙门氏菌的抑菌圈直径分别达到12～14mm、12～13mm、15～17mm,抑菌效果良好,可用于食品保鲜领域。(An acorn shell extract coating preservative and a preparation method thereof relate to a coating preservative and a preparation method thereof. The invention aims to provide an acorn shell extract coating preservative and a preparation method thereof. The acorn shell extract coating preservative is prepared from acorn shell extract, acorn starch ester, chitosan, sodium alginate, monoglyceride and water. The preparation method comprises the following steps: adding acorn starch ester, chitosan, sodium alginate and monoglyceride into partial water to obtain a mixed solution; and adding the acorn shell extract into the rest water, uniformly mixing, pouring into the mixed solution, and performing high-speed shearing treatment to obtain the acorn shell extract coating preservative. The diameters of inhibition zones for escherichia coli, staphylococcus aureus and salmonella respectively reach 12-14 mm, 12-13 mm and 15-17 mm, the antibacterial effect is good, and the antibacterial agent can be used in the field of food preservation.)

1. An acorn shell extract coating preservative is characterized by being prepared from 5-8 parts of acorn shell extract, 30-35 parts of acorn starch ester, 5-8 parts of chitosan, 6-10 parts of sodium alginate, 2-3 parts of monoglyceride and 1000 parts of distilled water in parts by mass.

2. A method for preparing the acorn shell extract coating preservative of claim 1, which is characterized by comprising the following steps:

weighing 5-8 parts of acorn shell extract, 30-35 parts of acorn starch ester, 5-8 parts of chitosan, 6-10 parts of sodium alginate, 2-3 parts of monoglyceride and 1000 parts of distilled water in parts by weight;

secondly, adding the weighed acorn starch ester, chitosan, sodium alginate and monoglyceride into three quarters of distilled water, stirring and heating to 70-75 ℃ to completely dissolve the acorn starch ester, the chitosan, the sodium alginate and the monoglyceride to obtain a mixed solution;

and thirdly, adding the weighed acorn shell extract into the rest distilled water, uniformly mixing, pouring the mixture into the mixed solution, and performing high-speed shearing treatment by using a high-shearing emulsifying machine to obtain the acorn shell extract coating preservative.

3. The preparation method of the acorn shell extract coating preservative according to claim 2, wherein the preparation method of the acorn shell extract in the first step is as follows:

(1) drying acorn shells at 50-60 ℃, crushing, and sieving with a 80-mesh sieve to obtain acorn shell powder;

(2) adding acorn shell powder into an extraction bottle, and mixing the acorn shell powder and the extraction bottle in a material-liquid ratio of 1: (18-20) adding an ethanol solution with the mass percentage concentration of 40% -80% as an extraction solvent, and performing ultrasonic extraction for 2-2.5 h at the temperature of 55-60 ℃; centrifuging the mixed solution at the rotating speed of 4000-5000 r/min for 10-15 min, and collecting supernatant; extracting the acorn shell residue for 2 times, and mixing the supernatants;

(3) and (3) carrying out vacuum rotary concentration on the supernatant at the temperature of 40-50 ℃, pre-freezing the concentrated solution at the temperature of-18-20 ℃, and finally carrying out vacuum freeze drying to obtain the acorn shell extract.

4. The preparation method of the acorn shell extract coating preservative according to claim 2 or 3, wherein the preparation method of the acorn starch ester in the step one is as follows:

(1) weighing acorn starch, octanoic acid, isopropanol and tween-80; wherein the volume ratio of the caprylic acid to the isopropanol is 1: (5-6); the mass of the Tween-80 is 2 to 3 percent of that of the octanoic acid; the sum of the mass of the caprylic acid and the isopropanol is 25 to 30 percent of the mass of the acorn starch;

(2) dispersing acorn starch in distilled water according to the mass percentage concentration of 30-35% of acorn starch, and adjusting the pH value to 8.2-8.6 by using 0.1M NaOH solution to obtain acorn starch suspension;

(3) mixing caprylic acid and isopropanol to obtain isopropanol caprylic acid solution;

(4) adding the acorn starch suspension into a high-speed shearing homogenizer, adding an isopropanol octanoic acid solution and tween-80 into the acorn starch suspension under the high-speed shearing homogenization condition, and finishing the addition of the isopropanol octanoic acid solution and the tween-80 within 2 hours; then carrying out esterification reaction for 5-6 h at the temperature of 30-35 ℃, and adjusting the pH to 7.0 by using 1M HCl solution to obtain a mixture;

(5) and (3) centrifuging the mixture, washing the solid phase with distilled water and absolute ethyl alcohol in sequence, drying the solid phase in an oven at the temperature of 40-45 ℃ for 18-30 hours, grinding the solid phase and passing through a 100-mesh sieve to obtain the acorn starch ester.

5. The preparation method of the acorn shell extract coating preservative according to claim 4, wherein the rotation speed of centrifugal treatment of the mixture in the step (5) is 4000-5000 r/min, and the centrifugal treatment time is 15-20 min.

6. The method for preparing the acorn shell extract coating preservative according to claim 2, wherein the high-speed shearing treatment in the third step is carried out for 10-15 min under the condition of 14000-16000 r/min.

Technical Field

The invention relates to a preparation method of a coating preservative.

Background

The food preservative is a food additive used for preventing the deterioration of food caused by the propagation of microorganisms in the processes of storage and circulation or the deterioration of the internal quality and the reduction of color of the food caused by improper storage and sale conditions, and prolonging the storage life and the edible value of the food. At present, chemical synthetic substances and natural substances are mainly used as food preservatives. The chemical synthesis preservative is mainly divided into an adsorption type preservative, a solution soaking type preservative, a fumigation type preservative and the like, the development of the preservative is rapid, the application is more, but the artificially synthesized preservative has the problem of toxic residue. The natural preservative mainly refers to a plant-derived preservative which is wide in source, safe, non-toxic and strong in practicability, can be collected from various plants such as fruits and vegetables, Chinese herbal medicines, spices and the like, has an obvious preservative and fresh-keeping function for many components, and is widely applied to the research of fruit and vegetable fresh-keeping at present. In foods eaten by people for a long time, the toxicity of the components of the natural preservative is far lower than that of the artificially synthesized preservative. Therefore, research for natural preservatives from the nature has attracted much attention from scientists in various countries.

Disclosure of Invention

The invention aims to provide an acorn shell extract coating preservative and a preparation method thereof.

The acorn shell extract coating preservative is prepared from 5-8 parts of acorn shell extract, 30-35 parts of acorn starch ester, 5-8 parts of chitosan, 6-10 parts of sodium alginate, 2-3 parts of monoglyceride and 1000 parts of distilled water in parts by mass.

The preparation method of the acorn shell extract coating preservative comprises the following steps:

weighing 5-8 parts of acorn shell extract, 30-35 parts of acorn starch ester, 5-8 parts of chitosan, 6-10 parts of sodium alginate, 2-3 parts of monoglyceride and 1000 parts of distilled water in parts by weight;

secondly, adding the weighed acorn starch ester, chitosan, sodium alginate and monoglyceride into three quarters of distilled water, stirring and heating to 70-75 ℃ to completely dissolve the acorn starch ester, the chitosan, the sodium alginate and the monoglyceride to obtain a mixed solution;

and thirdly, adding the weighed acorn shell extract into the rest distilled water, uniformly mixing, pouring the mixture into the mixed solution, and carrying out high-speed shearing treatment by using a high-shearing emulsifying machine to obtain the acorn shell extract coating preservative.

Further, the acorn shell extract is prepared by the following method:

(1) drying acorn shells at 50-60 ℃, crushing, and sieving with a 80-mesh sieve to obtain acorn shell powder;

(2) adding acorn shell powder into an extraction bottle, and mixing the acorn shell powder and the extraction bottle in a material-liquid ratio of 1: (18-20) adding an ethanol solution with the mass percentage concentration of 40% -80% as an extraction solvent, and performing ultrasonic extraction for 2-2.5 h at the temperature of 55-60 ℃; centrifuging the mixed solution at the rotating speed of 4000-5000 r/min for 10-15 min, and collecting supernatant; extracting the acorn shell residue for 2 times, and mixing the supernatants;

(3) and (3) carrying out vacuum rotary concentration on the supernatant at the temperature of 40-50 ℃, pre-freezing the concentrated solution at the temperature of-18-20 ℃, and finally carrying out vacuum freeze drying to obtain the acorn shell extract.

Further, the acorn starch ester is prepared as follows:

(1) weighing acorn starch, octanoic acid, isopropanol and tween-80; wherein the volume ratio of the caprylic acid to the isopropanol is 1: (5-6); the mass of the Tween-80 is 2 to 3 percent of that of the octanoic acid; the sum of the mass of the caprylic acid and the isopropanol is 25 to 30 percent of the mass of the acorn starch;

(2) dispersing acorn starch in distilled water according to the mass percentage concentration of 30-35% of acorn starch, and adjusting the pH value to 8.2-8.6 by using 0.1M NaOH solution to obtain acorn starch suspension;

(3) mixing caprylic acid and isopropanol to obtain isopropanol caprylic acid solution;

(4) adding the acorn starch suspension into a high-speed shearing homogenizer, adding an isopropanol octanoic acid solution and tween-80 into the acorn starch suspension under the high-speed shearing homogenization condition, and finishing the addition of the isopropanol octanoic acid solution and the tween-80 within 2 hours; then carrying out esterification reaction for 5-6 h at the temperature of 30-35 ℃, and adjusting the pH to 7.0 by using 1M HCl solution to obtain a mixture;

(5) and (3) centrifuging the mixture, washing the solid phase with distilled water and absolute ethyl alcohol in sequence, drying the solid phase in an oven at the temperature of 40-45 ℃ for 18-30 hours, grinding the solid phase and passing through a 100-mesh sieve to obtain the acorn starch ester.

Furthermore, the rotation speed of the centrifugal treatment of the mixture in the step (5) is 4000-5000 r/min, and the centrifugal treatment time is 15-20 min;

furthermore, the high-speed shearing treatment in the third step is to carry out high-speed shearing for 10-15 min under the condition of 14000-16000 r/min.

The application method of the acorn shell extract coating preservative is to spray the acorn shell extract coating preservative on a product to instantly form a preservative film layer on the surface of the product for preservation and bacteriostasis. The acorn shell extract contains various active ingredients such as catechol, anthoxanthin, compounds with glycosyl connected with anthocyanidin, and the like, and is an excellent natural food preservative. Not only has high safety, but also has soft color tone and certain physiological activity. The acorn starch ester is prepared by performing esterification reaction on medium-short chain fatty acid octanoic acid and acorn starch, has lipophilicity of medium-chain carbon chains and hydrophilicity of acorn starch hydroxyl, so that the adsorbability of an improved liquid film on a food-borne bacterial cell membrane is enhanced, and the effect of effective antibacterial ingredients in an acorn shell extract on bacteria is greatly improved. Meanwhile, the adsorption force and the stability of the liquid film on the meat product are enhanced, the dehydration rate of the product is delayed, and the quality of the product is ensured.

The acorn shell extract coating preservative of the invention fully exerts the bacteriostatic effect of natural substances such as polyphenol, flavone and the like in acorn shells on food-borne microorganisms. In the formula of the coating preservative, the acorn starch ester is used as an emulsifier for the first time, so that the targeting property of the preservative to bacteria and the adhesion on the surface of a product are improved, and the high-speed shearing technology is adopted for processing and processing, so that the bacteriostatic effect of the acorn shell extract coating preservative is improved, a stable bacteriostatic film is formed on the surface of the product, the dehydration rate of the product is delayed, the quality of the product is ensured, and the coating preservative is efficient, green and environment-friendly.

The diameter of an inhibition zone of the acorn shell extract coating preservative provided by the invention on escherichia coli is 12-14 mm, the diameter of an inhibition zone of staphylococcus aureus is 12-13 mm, and the diameter of an inhibition zone on salmonella is 15-17 mm. The bacteriostatic effect is better. The acorn shell extract coating preservative can be used in the field of food preservation.

Detailed Description

The following examples are used to demonstrate the beneficial effects of the present invention.

Example 1: the preparation method of the acorn shell extract coating preservative provided by the embodiment comprises the following steps of:

firstly, weighing 5g of acorn shell extract, 30g of acorn starch ester, 5g of chitosan, 6g of sodium alginate, 2g of monoglyceride and 1000mL of distilled water;

secondly, adding the weighed acorn starch ester, chitosan, sodium alginate and monoglyceride into 750mL of distilled water, stirring and heating to 75 ℃ to completely dissolve the acorn starch ester, the chitosan, the sodium alginate and the monoglyceride to obtain a mixed solution;

and thirdly, adding the weighed acorn shell extract into the residual 250mL of distilled water, uniformly mixing, pouring the mixture into the mixed solution, and carrying out high-speed shearing for 10min by using a high-shear emulsifying machine under the condition of 15000r/min to obtain the acorn shell extract coating preservative.

The preparation method of the acorn shell extract comprises the following steps:

(1) drying acorn shells at 60 ℃, crushing, and sieving with a 80-mesh sieve to obtain acorn shell powder;

(2) adding acorn shell powder into an extraction bottle, and mixing the acorn shell powder and the extraction bottle in a material-liquid ratio of 1: 20 adding an ethanol solution with the mass percentage concentration of 60 percent as an extraction solvent, and performing ultrasonic extraction for 2 hours at the temperature of 60 ℃; centrifuging the mixed solution at 4000r/min for 10min, and collecting supernatant; extracting the acorn shell residue for 2 times, and mixing the supernatants;

(3) vacuum concentrating the supernatant at 40 deg.C until the volume is reduced to one fifth of the original volume, pre-freezing the concentrated solution at-18 deg.C, and vacuum freeze drying to obtain acorn shell extract.

The preparation method of the acorn starch ester comprises the following steps:

(1) weighing 30g of acorn starch, 1.25g of octanoic acid, 6.25g of isopropanol and 25mg of tween-80; wherein the volume ratio of the caprylic acid to the isopropanol is 1: 5; the mass of the Tween-80 is 2 percent of that of the octanoic acid; the sum of the mass of the caprylic acid and the isopropanol is 25 percent of the mass of the acorn starch;

(2) dispersing acorn starch in distilled water according to the mass percentage concentration of 30% of acorn starch, and adjusting the pH value to 8.5 by using 0.1M NaOH solution to obtain acorn starch suspension;

(3) mixing caprylic acid and isopropanol to obtain isopropanol caprylic acid solution;

(4) adding the acorn starch suspension into a high-speed shearing homogenizer, adding an isopropanol octanoic acid solution and tween-80 into the acorn starch suspension under the high-speed shearing homogenization condition, and finishing the addition of the isopropanol octanoic acid solution and the tween-80 within 2 hours; then carrying out esterification reaction for 5h at the temperature of 35 ℃, and then adjusting the pH to 7.0 by using 1M HCl solution to obtain a mixture;

(5) centrifuging the mixture at 4000r/min for 15min, washing the solid phase with anhydrous ethanol twice, washing with distilled water three times, drying in an oven at 45 deg.C for 24 hr, grinding, and sieving with 100 mesh sieve to obtain acorn starch ester.

Comparative example 1: the comparative example is a preservative solution without adding acorn starch ester, and the preparation method of the preservative solution is as follows:

accurately weighing 5g of acorn shell extract, 5g of chitosan, 6g of sodium alginate, 2g of monoglyceride and distilled water to 1000 mL; wherein the acorn shell extract was the same as in example 1.

Adding chitosan, sodium alginate and monoglyceride into 750mL of distilled water, stirring and heating to 75 ℃ to completely dissolve the chitosan, the sodium alginate and the monoglyceride to obtain a mixed solution;

dissolving the weighed acorn shell extract into the residual 250mL of distilled water, and slowly pouring the acorn shell extract into the mixed solution; shearing at high speed for 10min at 15000r/min with high shear emulsifying machine to obtain preservative without adding acorn starch ester.

Comparative example 2: the comparative example is a preservative solution without adding tween-80 when preparing acorn starch ester, and the preparation method of the preservative solution is as follows:

firstly, preparing acorn starch ester, and the specific method comprises the following steps:

(1) weighing 30g of acorn starch, 1.25g of octanoic acid and 6.25g of isopropanol;

(2) dispersing acorn starch in distilled water according to the mass percentage concentration of 30% of acorn starch, and adjusting the pH value to 8.5 by using 0.1M NaOH solution to obtain acorn starch suspension;

(3) mixing caprylic acid and isopropanol to obtain isopropanol caprylic acid solution;

(4) adding the acorn starch suspension into a high-speed shearing homogenizer, adding an isopropanol caprylic acid solution into the acorn starch suspension under the high-speed shearing homogenizing condition, and finishing the addition of the isopropanol caprylic acid solution within 2 hours; then carrying out esterification reaction for 5h at the temperature of 35 ℃, and then adjusting the pH to 7.0 by using 1M HCl solution to obtain a mixture;

(5) centrifuging the mixture for 15 minutes under the condition of 4000r/min, washing a solid phase substance twice by using absolute ethyl alcohol, washing the solid phase substance three times by using distilled water, putting the solid phase substance into an oven, drying the solid phase substance for 24 hours under the condition of 45 ℃, grinding the solid phase substance and passing through a 100-mesh sieve to obtain acorn starch ester serving as a comparison;

the acorn starch ester used as the contrast is utilized to prepare the fresh-keeping liquid, and the specific method comprises the following steps:

weighing 5g of acorn shell extract, 30g of acorn starch ester serving as comparison, 5g of chitosan, 6g of sodium alginate, 2g of monoglyceride and 1000mL of distilled water;

secondly, adding the weighed acorn starch ester, chitosan, sodium alginate and monoglyceride serving as comparison into 750mL of distilled water, stirring and heating to 75 ℃ to completely dissolve the acorn starch ester, the chitosan, the sodium alginate and the monoglyceride to obtain a mixed solution;

and thirdly, adding the weighed acorn shell extract into the residual 250mL of distilled water, uniformly mixing, pouring the mixture into the mixed solution, and carrying out high-speed shearing for 10min by using a high-shear emulsifying machine under the condition of 15000r/min to obtain the comparative acorn shell extract coating preservative without adding Tween-80.

The results of the simultaneous bacteriostatic tests of the acorn shell extract coating preservative prepared in example 1, the comparative preservative without addition of acorn starch ester prepared in comparative example 1, the comparative preservative without addition of tween-80 prepared in comparative example 2, and the 0.5% acorn shell extract solution are shown in table 1.

TABLE 1 results of the bacteriostatic test

As can be seen from the comparison in table 1, the acorn shell extract coating preservative of example 1 had a zone of inhibition of 2.5 times that of the acorn shell extract solution of 0.5% for escherichia coli, 2.8 times that of the acorn shell extract solution of 0.5% for staphylococcus aureus, and 3.09 times that of the acorn shell extract solution of 0.5% for salmonella. Compared with the comparative example 1, the acorn starch ester is used as the emulsifier, so that the targeting property of the active ingredients in the preservative to bacteria and the adhesion on the surface of a product can be improved, a stable antibacterial film is formed on the surface of the product, and the antibacterial effect of the acorn shell extract is improved. Compared with the comparative example 2, the tween-80 is added during the preparation of the acorn starch ester, which plays an important role in improving the bacteriostatic effect of the preservative, and tween-8 is added during the preparation of the acorn starch ester, wherein tween-80 is an effective surfactant, and analysis shows that tween-80 effectively increases the esterification reaction efficiency of the acorn starch and caprylic acid during the preparation of the acorn starch ester, so that the esterification degree is improved, the emulsifying property and the adhesion property of the acorn starch ester are further improved, the method is beneficial to the film-forming property of the acorn shell extract coating preservative and the adhesion property to bacteria, and the bacteriostatic effect is improved.

Example 2: the preparation method of the acorn shell extract coating preservative provided by the embodiment comprises the following steps of:

weighing 8g of acorn shell extract, 35g of acorn starch ester, 6g of chitosan, 8g of sodium alginate, 3g of monoglyceride and 1000mL of distilled water;

secondly, adding the weighed acorn starch ester, chitosan, sodium alginate and monoglyceride into 750mL of distilled water, stirring and heating to 75 ℃ to completely dissolve the acorn starch ester, the chitosan, the sodium alginate and the monoglyceride to obtain a mixed solution;

and thirdly, adding the weighed acorn shell extract into the residual 250mL of distilled water, uniformly mixing, pouring the mixture into the mixed solution, and carrying out high-speed shearing for 15min by using a high-shear emulsifying machine under the condition of 14000r/min to obtain the acorn shell extract coating preservative.

The preparation method of the acorn shell extract comprises the following steps:

(1) drying acorn shells at 60 ℃, crushing, and sieving with a 80-mesh sieve to obtain acorn shell powder;

(2) adding acorn shell powder into an extraction bottle, and mixing the acorn shell powder and the extraction bottle in a material-liquid ratio of 1: 25 adding 80% ethanol solution as extraction solvent, and performing ultrasonic extraction at 60 deg.C for 2 hr; centrifuging the mixed solution at 4000r/min for 10min, and collecting supernatant; extracting the acorn shell residue for 2 times, and mixing the supernatants;

(3) vacuum concentrating the supernatant at 40 deg.C until the volume is reduced to one fifth of the original volume, pre-freezing the concentrated solution at-18 deg.C, and vacuum freeze drying to obtain acorn shell extract.

The preparation method of the acorn starch ester comprises the following steps:

(1) weighing 30g of acorn starch, 1.5g of octanoic acid, 7.5g of isopropanol and 45mg of tween-80; wherein the volume ratio of the caprylic acid to the isopropanol is 1: 5; the mass of the Tween-80 is 3 percent of that of the octanoic acid; the sum of the mass of the octanoic acid and the isopropanol is 30 percent of the mass of the acorn starch;

(2) dispersing acorn starch in distilled water according to the mass percentage concentration of 30% of acorn starch, and adjusting the pH value to 8.5 by using 0.1M NaOH solution to obtain acorn starch suspension;

(3) mixing caprylic acid and isopropanol to obtain isopropanol caprylic acid solution;

(4) adding the acorn starch suspension into a high-speed shearing homogenizer, adding an isopropanol octanoic acid solution and tween-80 into the acorn starch suspension under the high-speed shearing homogenization condition, and finishing the addition of the isopropanol octanoic acid solution and the tween-80 within 2 hours; then carrying out esterification reaction for 5h at the temperature of 35 ℃, and then adjusting the pH to 7.0 by using 1M HCl solution to obtain a mixture;

(5) centrifuging the mixture at 4000r/min for 15min, washing the solid phase with anhydrous ethanol twice, washing with distilled water three times, drying in an oven at 45 deg.C for 24 hr, grinding, and sieving with 100 mesh sieve to obtain acorn starch ester.

The diameter of the zone of inhibition of the acorn shell extract coating preservative of the embodiment 2 on escherichia coli is 13.94 +/-0.29 mm, the diameter of the zone of inhibition of staphylococcus aureus is 12.76 +/-0.24 mm, and the diameter of the zone of inhibition of salmonella is 16.83 +/-0.42 mm. The bacteriostatic effect is better.