CN103113603A - Edible packaging film capable of indicating food rancidity and preparation method thereof - Google Patents

Abstract

Translated fromChinese

本发明公开了属于食品包装材料技术领域的一种指示食物酸败的可食用包装膜及其制备方法。所述可食用包装膜是在添加增塑剂的情况下将乳清蛋白溶液和天然花青素提取物混合而制成的。本发明还公开了该pH变色型可食用包装膜的制备方法。该包装对pH敏感，可随外界环境pH的变化而显示出不同的颜色：酸性环境中为红色、碱性环境中为蓝色，且颜色随pH的变化而变化。本发明安全性高，食用具有营养功能，且pH变色反应灵敏，作为包装与食品接触时包装内膜的颜色随着食物所处的环境而变化，从而根据包装膜的不同颜色可指示食品是否酸败，方法方便准确。The invention discloses an edible packaging film indicating food rancidity and a preparation method thereof, which belong to the technical field of food packaging materials. The edible packaging film is made by mixing whey protein solution and natural anthocyanin extract under the condition of adding plasticizer. The invention also discloses a preparation method of the pH color-changing edible packaging film. The packaging is sensitive to pH and can display different colors with the change of the pH of the external environment: red in an acidic environment and blue in an alkaline environment, and the color changes with the change of pH. The invention has high safety, has nutritional function when eaten, and is sensitive to pH change and color change. When the packaging is in contact with food, the color of the packaging inner film changes with the environment in which the food is located, so that it can indicate whether the food is rancid according to the different colors of the packaging film. , the method is convenient and accurate.

Description

Translated fromChinese

一种指示食物酸败的可食用包装膜及其制备方法Edible packaging film indicating food rancidity and preparation method thereof

技术领域technical field

本发明属于食品包装材料技术领域，具体涉及一种指示食物酸败的可食用包装膜及其制备方法。The invention belongs to the technical field of food packaging materials, and in particular relates to an edible packaging film indicating food rancidity and a preparation method thereof.

背景技术Background technique

近年来人们的环保意识和食品安全意识不断增强，相比传统塑料包装材料，符合可持续发展原则、安全性更高的绿色包装材料更加受到青睐，可食用包装膜以其安全、无毒、环保、可食用且兼具营养性和风味等特点而备受关注。然而，可食用包装膜在我国食品行业的应用尚处于起步阶段，现有膜的研究和应用多集中在物化性质、提高机械强度等方面，作为生物高聚物的网络结构，包装膜的载体功能受到越来越多的关注，人们期望通过各种成分的添加提高膜的营养价值和功能性。In recent years, people's awareness of environmental protection and food safety has been continuously enhanced. Compared with traditional plastic packaging materials, green packaging materials that conform to the principle of sustainable development and have higher safety are more popular. Edible packaging films are safe, non-toxic and environmentally friendly. , edible and has the characteristics of nutrition and flavor and has attracted much attention. However, the application of edible packaging films in my country's food industry is still in its infancy. The research and application of existing films are mostly focused on physical and chemical properties, improving mechanical strength, etc., as the network structure of biopolymers, the carrier function of packaging films It has received more and more attention, and people expect to improve the nutritional value and functionality of the membrane through the addition of various components.

由于微生物繁殖、化学反应等因素导致的食品腐败变质过程经常发生。但是在腐败初期或针对不同的体系，食品感官往往没有明显的变化，因此人们极易误食而发生食品安全危害，存在较大的风险。研究表明，食品的腐败往往伴随着pH的变化，对食品体系pH的监测可以在一定程度上反应腐败变质的程度。因此，开发一种使用方便、准确率高、安全性好的天然、可食性指示剂，对于指示食品腐败程度、预防食品安全风险具有重要的意义。The process of food spoilage due to factors such as microbial reproduction and chemical reactions often occurs. However, in the early stage of spoilage or for different systems, there is often no obvious change in food sensory, so people are very easy to eat it by mistake and cause food safety hazards, and there is a greater risk. Studies have shown that food spoilage is often accompanied by changes in pH, and monitoring the pH of food systems can reflect the degree of spoilage to a certain extent. Therefore, it is of great significance to develop a natural and edible indicator that is easy to use, has high accuracy, and is safe, for indicating the degree of food spoilage and preventing food safety risks.

乳清蛋白是干酪生产的副产物，营养价值高，容易被人体吸收，且具有良好的成膜能力，可以形成柔软、有弹性、不溶于水、在一定的湿度下具有优良的氧气、芳香物质和油脂阻隔性能的透明薄膜，因而成为新型的可食用包装材料。花青素是自然界一类广泛存在于植物中的水溶性天然色素。花青素为人体带来多种益处，它是一种有效的抗氧化剂，能够保护人体免受自由基损伤，还能够增强血管弹性，改善循环系统，增进皮肤的光滑度，抑制炎症和过敏，改善关节的柔韧性等。花青素有一个重要性质，即对pH敏感，可呈蓝、紫、红、橙等不同色泽，比如在碱性介质为蓝色，在酸性介质中为紫红色。此性质可用于指示食品体系的酸碱度。花青素可从常见的天然食材如甘蓝、紫薯、紫米、蓝莓、葡萄皮等中提取，由于不同的品种提取的花青素pH敏感性不同，故可用于指示不同食物的酸败。将花青素和可食用膜结合，当包装膜中的花青素与食品接触时，可感应体系的酸碱度，根据颜色的变化指示食品的酸败程度。同时，可食用膜的网络结构可对不稳定的花青素起保护作用。这为新型营养性和功能性可食用膜的开发提供了新的思路。通过对国内外专利文献、期刊杂志及其他公开发表的文献进行检索，本发明在国内外未见报道。Whey protein is a by-product of cheese production. It has high nutritional value, is easily absorbed by the human body, and has good film-forming ability, which can form soft, elastic, water-insoluble, excellent oxygen, and aromatic substances It is a transparent film with oil and grease barrier properties, so it has become a new type of edible packaging material. Anthocyanins are a class of water-soluble natural pigments that widely exist in plants in nature. Anthocyanin brings many benefits to the human body. It is an effective antioxidant that can protect the human body from free radical damage. It can also enhance the elasticity of blood vessels, improve the circulatory system, improve the smoothness of the skin, inhibit inflammation and allergies, Improve joint flexibility, etc. Anthocyanins have an important property, that is, they are sensitive to pH, and can have different colors such as blue, purple, red, orange, etc. For example, they are blue in alkaline medium and purple in acidic medium. This property can be used to indicate the pH of food systems. Anthocyanins can be extracted from common natural ingredients such as cabbage, purple sweet potato, purple rice, blueberry, grape skin, etc. Since anthocyanins extracted from different varieties have different pH sensitivities, they can be used to indicate the rancidity of different foods. Combining anthocyanin and edible film, when the anthocyanin in the packaging film is in contact with food, it can sense the pH of the system and indicate the rancidity of the food according to the color change. At the same time, the network structure of the edible film can protect the unstable anthocyanins. This provides new ideas for the development of novel nutritional and functional edible films. By searching domestic and foreign patent documents, periodicals and other published documents, the present invention has not been reported at home and abroad.

发明内容Contents of the invention

本发明的目的在于提供一种指示食物酸败的可食用包装膜及其制备方法。The purpose of the present invention is to provide an edible packaging film indicating food rancidity and a preparation method thereof.

一种指示食物酸败的可食用包装膜的制备方法，包括以下方法步骤：A method for preparing an edible packaging film indicating food rancidity, comprising the following method steps:

（1）将乳清蛋白加入到水中搅拌使其充分溶解，加热，冷却至室温，制备乳清蛋白溶液；(1) Add whey protein to water and stir to fully dissolve, heat, and cool to room temperature to prepare whey protein solution;

上述将乳清蛋白加入到水中搅拌使其充分溶解后，先调节溶液pH值为7-9，再加热。After the whey protein is added into the water and stirred to make it fully dissolved, the pH of the solution is first adjusted to 7-9, and then heated.

上述加热温度为30-100℃，加热时间为1-600 min。The above-mentioned heating temperature is 30-100°C, and the heating time is 1-600 min.

优选的，上述加热其温度为80-90℃，加热时间为20-30 min。Preferably, the temperature of the above-mentioned heating is 80-90°C, and the heating time is 20-30 min.

（2）从天然食材中提取花青素，制备天然花青素提取物；(2) Extract anthocyanins from natural food materials to prepare natural anthocyanin extracts;

所述从天然食材中提取花青素的方法为：将天然食材洗净，切块，取100 g，加入100-150 g去离子水中，打浆1-5分钟，纱布过滤，滤液过350目筛，收集滤液，10000-12000 r/min离心5-10 min，收集上清液即为天然花青素提取物。The method for extracting anthocyanins from natural ingredients is as follows: wash the natural ingredients, cut into pieces, take 100 g, add 100-150 g of deionized water, beat for 1-5 minutes, filter with gauze, and pass the filtrate through a 350-mesh sieve , collect the filtrate, centrifuge at 10000-12000 r/min for 5-10 min, and collect the supernatant which is the natural anthocyanin extract.

所述从天然食材为紫甘蓝、紫薯、葡萄皮、黑莓、樱桃、茄子皮、蓝莓、红莓、草莓、桑葚、山楂皮、紫米或红小豆。The natural ingredients are purple cabbage, purple sweet potato, grape skin, blackberry, cherry, eggplant skin,blueberry ,cranberry ,strawberry , mulberry, hawthorn skin, purple rice or red bean.

（3）将乳清蛋白溶液和天然花青素提取物混合得混合液，其中乳清蛋白的质量百分比浓度为1-10%，天然花青素提取物的质量百分比浓度为10-40%，然后向混合液中加入增塑剂，混合均匀并超声脱气，得到成膜液，成膜后为所述可食用包装膜；其中，增塑剂与乳清蛋白的质量比为（0.1-0.8）：1，所述增塑剂为甘油或山梨醇。(3) Mixing whey protein solution and natural anthocyanin extract to obtain a mixed solution, wherein the mass percentage concentration of whey protein is 1-10%, and the mass percentage concentration of natural anthocyanin extract is 10-40%, Then add a plasticizer to the mixed solution, mix evenly and degas by ultrasonic to obtain a film-forming liquid, which is the edible packaging film after film-forming; wherein, the mass ratio of the plasticizer to whey protein is (0.1-0.8 ): 1, the plasticizer is glycerin or sorbitol.

上述制备方法得到的指示食物酸败的可食用包装膜，由于从不同的天然食材提取的花青素pH敏感性不同，会随外界pH的变化而显示出不同的颜色，可用于指示不同食物的酸败。The edible packaging film indicating food rancidity obtained by the above preparation method, due to the different pH sensitivity of the anthocyanins extracted from different natural materials, will show different colors with the change of external pH, and can be used to indicate the rancidity of different foods .

本发明的有益效果为：原料乳清蛋白为干酪生产的副产物，营养价值高，容易被人体吸收，花青素本身具有良好的生理功能活性。将花青素提取物与乳清蛋白结合制成可食用膜，使用具有良好的营养价值和功能性。且该膜对pH敏感，可通过颜色变化指示环境pH，可以直观的显示食品体系的酸败程度，方法方便准确。The invention has the beneficial effects that: the raw whey protein is a by-product of cheese production, has high nutritional value and is easily absorbed by the human body, and the anthocyanin itself has good physiological function and activity. Combining anthocyanin extract with whey protein to make an edible film has good nutritional value and functionality. Moreover, the film is sensitive to pH, can indicate the pH of the environment through color changes, and can visually display the rancidity degree of the food system, and the method is convenient and accurate.

附图说明Description of drawings

图1为酸败过程中平均pH变化与菌落总数关系。Figure 1 shows the relationship between the average pH change and the total number of colonies during the rancidity process.

具体实施方式Detailed ways

以下实施例中关于膜厚度、拉伸性能、水蒸汽透过系数以及含水量和溶解性的测定方法如下：The assay methods about film thickness, tensile properties, water vapor transmission coefficient and water content and solubility in the following examples are as follows:

（1）膜厚度的测定方法：用数显千分尺测量厚度。(1) Measuring method of film thickness: Measure the thickness with a digital display micrometer.

（2）拉伸性能的测定方法(2) Determination of tensile properties

参照ASTM(1995)法，使用TMS-Pro质构仪测定拉伸性能，其中拉伸速度为1 mm/s。拉伸强度（TS, MPa）按式（1）计算：Referring to the ASTM (1995) method, the tensile properties were measured using a TMS-Pro texture analyzer, where the tensile speed was 1 mm/s. Tensile strength (TS, MPa) is calculated according to formula (1):

$\mathrm{<span><span>TS</span>TS</span>}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>F</span>f</span>}}_{\mathrm{<span><span>t</span>t</span>}}}{\mathrm{<span><span>L</span>L</span>}<span><span>\&times;</span>\&times;</span>\mathrm{<span><span>W</span>W</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>1</span>1</span>}<span><span>)</span>)</span>$

式中，F_t ——最大拉力（N）In the formula, F_t ——Maximum pulling force (N)

L ——膜样品的厚度（mm）L - the thickness of the film sample (mm)

W ——膜样品的宽度（mm）W - the width of the film sample (mm)

断裂拉伸率（E，%）按式（2）计算：Elongation at break (E,%) is calculated according to formula (2):

$\mathrm{<span><span>E</span>E.</span>}<span><span>(</span>(</span><span><span>\%</span>\%</span><span><span>)</span>)</span><span><span>=</span>=</span>\frac{\mathrm{<span><span>\&Delta;L</span>\&Delta;<figure-callout\; label="L\; L"\; filenames="HDA00002886080300011.png"\; state="\{\{state\}\}">L</figure-callout></span><figure-callout\; label="L\; L"\; filenames="HDA00002886080300011.png"\; state="\{\{state\}\}"></figure-callout>}}{{\mathrm{<span><span></span></span>}}_{}}<span><span>\&times;</span>\&times;</span>\mathrm{<span><span>100</span>100</span>}<span><span>\%</span>\%</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}<span><span>)</span>)</span>$

式中，L₀ ——样品拉伸前的原始长度（mm）In the formula, L₀ - the original length of the sample before stretching (mm)

ΔL ——样品断裂被拉长的长度（mm）ΔL——The length of the sample broken and elongated (mm)

（3）水蒸汽透过系数（WVP）的测定方法(3) Determination method of water vapor transmission coefficient (WVP)

参照GB 1037-88法，采用拟杯子法，并加以适当调整后测定。水蒸气透过系数按式（3）计算：Refer to the GB 1037-88 method, adopt the quasi-cup method, and make appropriate adjustments for determination. The water vapor transmission coefficient is calculated according to formula (3):

$\mathrm{<span><span>WVP</span>WVP</span>}<span><span>(</span>(</span>\mathrm{<span><span>g</span>g</span>}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\mathrm{<span><span>mm</span>mm</span>}<span><span>/</span>/</span>{\mathrm{<span><span>m</span><figure-callout\; label="m"\; filenames="HDA00002886080300011.png"\; state="\{\{state\}\}">m</figure-callout></span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\mathrm{<span><span>h</span>h</span>}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\mathrm{<span><span>kPa</span>kPa</span>}<span><span>)</span>)</span><span><span>=</span>=</span>\frac{\mathrm{<span><span>W</span>W</span>}<span><span>\&times;</span>\&times;</span>\mathrm{<span><span>x</span>x</span>}}{\mathrm{<span><span>A</span>A</span>}<span><span>\&times;</span>\&times;</span>\mathrm{<span><span>T</span>T</span>}<span><span>\&times;</span>\&times;</span>\mathrm{<span><span>\&Delta;P</span>\&Delta;P</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>3</span>3</span>}<span><span>)</span>)</span>$

式中，W —— 透湿杯的增重(g)In the formula, W - the weight gain of the moisture-permeable cup (g)

x —— 膜的厚度(mm)x - the thickness of the film (mm)

A —— 膜外露面积(cm²)A —— membrane exposed area (cm² )

T —— 测量间隔时间(h)T - measurement interval time (h)

△P ——膜两侧的水蒸气压差(kPa)△P——water vapor pressure difference on both sides of the membrane (kPa)

（4）含水量和溶解性的测定方法(4) Determination method of water content and solubility

称取质量为m₀的膜放在105℃的烘箱中干燥24 h，称重，计算干燥前后膜质量损失为Δm。含水量按式（4）计算：Weigh the film with a mass of m₀ and dry it in an oven at 105 °C for 24 h, weigh it, and calculate the mass loss of the film before and after drying as Δm. The water content is calculated according to formula (4):

$\mathrm{<span><span>MC</span>MC</span>}<span><span>(</span>(</span><span><span>\%</span>\%</span><span><span>)</span>)</span><span><span>=</span>=</span>\frac{\mathrm{<span><span>\&Delta;m</span>\&Delta;m</span>}}{{\mathrm{<span><span>m</span><figure-callout\; label="m"\; filenames="HDA00002886080300011.png"\; state="\{\{state\}\}">m</figure-callout></span>}}_{\mathrm{<span><span>0</span>0</span>}}}<span><span>\&times;</span>\&times;</span>\mathrm{<span><span>100</span>100</span>}<span><span>\%</span>\%</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>4</span>4</span>}<span><span>)</span>)</span>$

（5）pH值的测定方法：用数显pH计测定。(5) Measuring method of pH value: measured with a digital display pH meter.

（6）菌落总数的测定方法：按GB4789.2-2010测定。(6) Determination method of the total number of bacterial colonies: according to GB4789.2-2010.

下面结合具体实施例对本发明进一步说明，但本发明不限于以下实施例。The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples.

实施例1Example 1

制备方法：Preparation:

（1）乳清蛋白溶液的制备：将乳清蛋白加入到水中持续搅拌使其充分溶解，调节乳清蛋白溶液pH值为8，80℃加热30 min，冷却至室温，制得的乳清蛋白溶液；(1) Preparation of whey protein solution: Add whey protein into water and stir continuously to dissolve it fully, adjust the pH value of whey protein solution to 8, heat at 80°C for 30 min, cool to room temperature, and the prepared whey protein solution;

（2）紫薯或紫甘蓝天然花青素提取物的制备：将紫薯或紫甘蓝洗净，切块，称取100 g，加入150 g去离子水，打浆机打浆2分钟，纱布过滤，滤液过350目筛。收集滤液，12000 r/min离心8 min，收集上清液即为紫薯或紫甘蓝天然花青素提取物；(2) Preparation of natural anthocyanin extract from purple sweet potato or purple cabbage: Wash purple sweet potato or purple cabbage, cut into pieces, weigh 100 g, add 150 g of deionized water, beat with a beater for 2 minutes, filter with gauze, The filtrate is passed through a 350 mesh sieve. Collect the filtrate, centrifuge at 12000 r/min for 8 min, and collect the supernatant which is the natural anthocyanin extract of purple sweet potato or purple cabbage;

（3）将乳清蛋白溶液和紫薯或紫甘蓝天然花青素提取物混合，制得的混合液中乳清蛋白的质量百分比浓度为8%，紫薯或紫甘蓝天然花青素提取物的质量百分比浓度为19%，然后向混合后的溶液中加入甘油，混合均匀并超声脱气，得到成膜液，其中，甘油的质量百分比浓度为4.8%；(3) Mix the whey protein solution with the natural anthocyanin extract of purple potato or purple cabbage, the mass percentage concentration of whey protein in the prepared mixture is 8%, and the natural anthocyanin extract of purple potato or purple cabbage The mass percent concentration of glycerol is 19%, then glycerin is added to the mixed solution, mixed uniformly and ultrasonically degassed to obtain a film-forming liquid, wherein the mass percent concentration of glycerol is 4.8%;

（4）采用流延法将步骤（3）的成膜液加入到平底有机玻璃器皿中，其中，成膜液的用量为0.1 g/cm²，在22±2℃，相对湿度为56±2%的条件下平衡48 h，制得pH变色型可食用包装膜。(4) Add the film-forming solution in step (3) into a flat-bottomed plexiglass container by casting method, wherein the amount of film-forming solution is 0.1 g/cm² , at 22±2°C, the relative humidity is 56±2 % under the condition of equilibrating for 48 h to prepare a pH-changing edible packaging film.

经过测试，可食用包装膜厚度为106.1±9.6 μm，拉伸强度为4.15±0.40 MPa，断裂拉伸率为47.3±5.1%，水蒸气透过率为1.68±0.05 g·mm/ h·m² ·kPa，含水量为28.1±1.4%，溶解性为19.9±0.7%。After testing, the thickness of the edible packaging film is 106.1±9.6 μm, the tensile strength is 4.15±0.40 MPa, the elongation at break is 47.3±5.1%, and the water vapor transmission rate is 1.68±0.05 g·mm/h·m² ·kPa, water content is 28.1±1.4%, solubility is 19.9±0.7%.

含紫薯天然花青素提取物的包装膜呈紫色，含紫甘蓝天然花青素提取物的包装膜呈蓝绿色，二者随pH变化规律如表1所示。The packaging film containing the natural anthocyanin extract of purple sweet potato was purple, and the packaging film containing the natural anthocyanin extract of purple cabbage was blue-green. The changes of the two with pH are shown in Table 1.

表1为指示食物酸败的可食用包装膜在不同pH环境下的颜色变化规律Table 1 shows the color change law of the edible packaging film indicating food rancidity under different pH environments

实施例2Example 2

制备方法：Preparation:

（1）乳清蛋白溶液的制备：将乳清蛋白加入到水中持续搅拌使其充分溶解，调节乳清蛋白溶液pH值为9，85℃加热25 min，冷却至室温，得到乳清蛋白溶液；(1) Preparation of whey protein solution: Add whey protein into water and keep stirring to fully dissolve it, adjust the pH value of the whey protein solution to 9, heat at 85°C for 25 min, and cool to room temperature to obtain a whey protein solution;

（2）天然花青素提取物的制备：将紫甘蓝洗净，切块，称取100 g，加入130 g去离子水，打浆机打浆4分钟，纱布过滤，滤液过350目筛。收集滤液，10000 r/min离心10 min，收集上清液即为紫甘蓝天然花青素提取物；(2) Preparation of natural anthocyanin extract: Wash purple cabbage, cut into pieces, weigh 100 g, add 130 g of deionized water, beat with a beater for 4 minutes, filter with gauze, and pass the filtrate through a 350-mesh sieve. Collect the filtrate, centrifuge at 10000 r/min for 10 min, and collect the supernatant which is the natural anthocyanin extract of purple cabbage;

（3）将乳清蛋白溶液和紫甘蓝天然花青素提取物混合，制得的混合液中乳清蛋白的质量百分比浓度为8%，紫甘蓝天然花青素提取物的质量百分比浓度为25%，然后向混合后的溶液中加入山梨醇，混合均匀并超声脱气，得到成膜液，其中，山梨醇的质量百分比浓度为4%；(3) Mix the whey protein solution and the natural anthocyanin extract of purple cabbage, the mass percentage concentration of the whey protein in the prepared mixture is 8%, and the mass percentage concentration of the natural anthocyanin extract of purple cabbage is 25% %, then add sorbitol to the mixed solution, mix homogeneously and ultrasonic degassing, obtain film-forming liquid, wherein, the mass percent concentration of sorbitol is 4%;

（4）采用流延法将步骤（3）的成膜液加入到平底有机玻璃器皿中，其中，成膜液的用量为0.15 g/cm²，在22±1℃，相对湿度为56±2%的条件下平衡60 h，制得pH变色型可食用包装膜，膜的颜色为蓝绿色；(4) Add the film-forming solution in step (3) into a flat-bottomed plexiglass container by casting method, wherein the amount of film-forming solution is 0.15 g/cm² , at 22±1°C, the relative humidity is 56±2 % under the condition of equilibrating for 60 h, the pH color-changing edible packaging film was prepared, and the color of the film was blue-green;

（5）将步骤（4）制得的pH变色型可食用包装膜包裹经100℃烹煮2h后的带汁熟牛肉，其酸败过程中平均pH变化与菌落总数关系，如图1所示，其中CFU为菌落形成单位(Colony-Forming Units) ，根据国标GB2726-2005熟肉制品卫生标准对菌落总数的要求，当pH为6-7时，膜的颜色为蓝紫色，无可识别酸腐现象，菌落总数符合要求，可以食用，当pH为5-6时，膜的颜色为紫红色，无可识别酸腐现象，菌落总数符合超标，不可食用，当pH为4-5时，膜的颜色为红色，有可识别酸腐现象，不可食用。(5) Wrap the cooked beef with juice cooked at 100°C for 2 hours with the pH-changing edible packaging film prepared in step (4). The relationship between the average pH change and the total number of colonies during the rancidity process is shown in Figure 1. Among them, CFU is Colony-Forming Units. According to the national standard GB2726-2005 hygienic standard for cooked meat products, the total number of colonies is required. When the pH is 6-7, the color of the film is blue-purple, and there is no identifiable sour phenomenon , the total number of colonies meets the requirements and can be eaten. When the pH is 5-6, the color of the film is purple red, and there is no identifiable sour rot phenomenon. The total number of colonies exceeds the standard and is inedible. It is red, with identifiable sourness and rot, and is inedible.

实施例3Example 3

制备方法：Preparation:

（1）乳清蛋白溶液的制备：将乳清蛋白加入到水中持续搅拌使其充分溶解，调节乳清蛋白溶液pH值为7.5，80℃加热60 min，冷却至室温，制得的乳清蛋白溶液；(1) Preparation of whey protein solution: Add whey protein into water and stir continuously to dissolve it fully, adjust the pH value of whey protein solution to 7.5, heat at 80°C for 60 min, and cool to room temperature to obtain whey protein solution;

（2）紫米或红小豆天然花青素提取物的制备：称取100 g，加入150g去离子水，打浆机打浆2分钟，纱布过滤，滤液过350目筛。收集滤液，12000 r/min离心8 min，收集上清液即为紫米或红小豆天然花青素提取物；(2) Preparation of natural anthocyanin extract from purple rice or red bean: weigh 100 g, add 150 g of deionized water, beat with a beater for 2 minutes, filter with gauze, and pass the filtrate through a 350-mesh sieve. Collect the filtrate, centrifuge at 12000 r/min for 8 min, and collect the supernatant which is the natural anthocyanin extract of purple rice or red bean;

（3）将乳清蛋白溶液和紫米或红小豆天然花青素提取物混合，制得的混合液中乳清蛋白的质量百分比浓度为9%，紫米或红小豆天然花青素提取物的质量百分比浓度为17%，然后向混合后的溶液中加入甘油，混合均匀并超声脱气，得到成膜液，其中，甘油的质量百分比浓度为5.1%；(3) Mix the whey protein solution with the natural anthocyanin extract of purple rice or red bean, the mass percentage concentration of whey protein in the prepared mixture is 9%, and the natural anthocyanin extract of purple rice or red bean The mass percent concentration of glycerol is 17%, and then glycerin is added to the mixed solution, mixed uniformly and ultrasonically degassed to obtain a film-forming liquid, wherein the mass percent concentration of glycerin is 5.1%;

（4）采用流延法将步骤（3）的成膜液加入到平底有机玻璃器皿中，其中，成膜液的用量为0.13 g/cm²，在23±1℃，相对湿度为58±2%的条件下平衡48 h，制得pH变色型可食用包装膜。(4) Add the film-forming solution in step (3) into a flat-bottomed plexiglass vessel by casting method, wherein the amount of film-forming solution is 0.13 g/cm² , at 23±1°C, the relative humidity is 58±2 % under the condition of equilibrating for 48 h to prepare a pH-changing edible packaging film.

经过测试，可食用包装膜厚度为105.1±4.7 μm，拉伸强度为3.96±0.60 MPa，断裂拉伸率为41.9±7.2%，水蒸气透过率为1.90±0.14g·mm/ h·m² ·kPa，含水量为26.2±0.9%，溶解性为18.2±1.1%。After testing, the thickness of the edible packaging film is 105.1±4.7 μm, the tensile strength is 3.96±0.60 MPa, the elongation at break is 41.9±7.2%, and the water vapor transmission rate is 1.90±0.14g·mm/h·m² ·kPa, water content is 26.2±0.9%, solubility is 18.2±1.1%.

含紫米天然花青素提取物的包装膜呈紫色，含红小豆天然花青素提取物的包装膜呈紫红色，其均可在pH变化时，其颜色发生变化。The packaging film containing the natural anthocyanin extract of purple rice is purple, and the packaging film containing the natural anthocyanin extract of red bean is purple red, and both of them can change in color when the pH changes.

实施例4Example 4

制备方法：Preparation:

（1）乳清蛋白溶液的制备：将乳清蛋白加入到水中持续搅拌使其充分溶解，调节乳清蛋白溶液pH值为8.5，75℃加热120 min，冷却至室温，制得的乳清蛋白溶液；(1) Preparation of whey protein solution: Add whey protein into water and stir continuously to dissolve it fully, adjust the pH value of whey protein solution to 8.5, heat at 75°C for 120 min, cool to room temperature, and the prepared whey protein solution;

（2）葡萄皮或蓝莓天然花青素提取物的制备：称取100 g，加入140g去离子水，打浆机打浆3分钟，纱布过滤，滤液过350目筛。收集滤液，11000 r/min离心9 min，收集上清液即为葡萄皮或蓝莓天然花青素提取物；(2) Preparation of natural anthocyanin extract from grape skin or blueberry: weigh 100 g, add 140 g of deionized water, beat with a beater for 3 minutes, filter with gauze, and pass the filtrate through a 350-mesh sieve. Collect the filtrate, centrifuge at 11000 r/min for 9 min, and collect the supernatant which is the natural anthocyanin extract of grape skin or blueberry;

（3）将乳清蛋白溶液和葡萄皮或蓝莓天然花青素提取物混合，制得的混合液中乳清蛋白的质量百分比浓度为8.6%，葡萄皮或蓝莓天然花青素提取物的质量百分比浓度为24%，然后向混合后的溶液中加入山梨醇，混合均匀并超声脱气，得到成膜液，其中，山梨醇的质量百分比浓度为4.7%；(3) Mix whey protein solution with grape skin or blueberry natural anthocyanin extract, the mass percentage concentration of whey protein in the prepared mixture is 8.6%, the mass percentage of grape skin or blueberry natural anthocyanin extract The percentage concentration is 24%, then add sorbitol to the mixed solution, mix well and ultrasonic degassing, obtain film-forming liquid, wherein, the mass percent concentration of sorbitol is 4.7%;

（4）采用流延法将步骤（3）的成膜液加入到平底有机玻璃器皿中，其中，成膜液的用量为0.15 g/cm²，在25±2℃，相对湿度为50±3%的条件下平衡48 h，制得pH变色型可食用包装膜。(4) Add the film-forming solution in step (3) into a flat-bottomed plexiglass container by casting method, wherein the amount of film-forming solution is 0.15 g/cm² , at 25±2°C, the relative humidity is 50±3 % under the condition of equilibrating for 48 h to prepare a pH-changing edible packaging film.

经过测试，可食用包装膜厚度为110.1±5.1 μm，拉伸强度为4.11±0.71 MPa，断裂拉伸率为45.1±3.8%，水蒸气透过率为2.01±0.08g·mm/ h·m² ·kPa，含水量为23.4±1.1%，溶解性为20.7±1.6%。After testing, the thickness of the edible packaging film is 110.1±5.1 μm, the tensile strength is 4.11±0.71 MPa, the elongation at break is 45.1±3.8%, and the water vapor transmission rate is 2.01±0.08g·mm/h·m² ·kPa, water content is 23.4±1.1%, solubility is 20.7±1.6%.

含葡萄皮天然花青素提取物的包装膜呈蓝紫色，含蓝莓天然花青素提取物的包装膜呈蓝绿色，其均可在pH变化时，其颜色发生变化。The packaging film containing the natural anthocyanin extract of grape skin is blue-purple, and the packaging film containing the natural anthocyanin extract of blueberry is blue-green, and both of them can change in color when the pH changes.

Claims (8)

Translated fromChinese

1.一种指示食物酸败的可食用包装膜的制备方法，其特征在于，包括以下方法步骤：1. A preparation method of an edible packaging film indicating food rancidity, characterized in that, comprising the following method steps:（1）将乳清蛋白加入到水中搅拌使其充分溶解，加热，冷却至室温，制备乳清蛋白溶液；(1) Add whey protein to water and stir to fully dissolve, heat, and cool to room temperature to prepare whey protein solution;（2）从天然食材中提取花青素，制备天然花青素提取物；(2) Extract anthocyanins from natural food materials to prepare natural anthocyanin extracts;（3）将乳清蛋白溶液和天然花青素提取物混合得混合液，其中乳清蛋白的质量百分比浓度为1-10%，天然花青素提取物的质量百分比浓度为10-40%，然后向混合液中加入增塑剂，混合均匀并超声脱气，得到成膜液，成膜后为所述可食用包装膜；其中，增塑剂与乳清蛋白的质量比为（0.1-0.8）：1。(3) Mixing whey protein solution and natural anthocyanin extract to obtain a mixed solution, wherein the mass percentage concentration of whey protein is 1-10%, and the mass percentage concentration of natural anthocyanin extract is 10-40%, Then add a plasticizer to the mixed solution, mix evenly and degas by ultrasonic to obtain a film-forming solution, which is the edible packaging film after film-forming; wherein, the mass ratio of the plasticizer to whey protein is (0.1-0.8 ):1.2.根据权利要求1所述的指示食物酸败的可食用包装膜的制备方法，其特征在于，步骤（1）中，所述将乳清蛋白加入到水中搅拌使其充分溶解后，先调节溶液pH值为7-9，再加热。2. The method for preparing an edible packaging film indicating food rancidity according to claim 1, characterized in that in step (1), after adding whey protein into water and stirring to fully dissolve it, first adjust the solution pH 7-9, reheat.3.根据权利要求1所述的指示食物酸败的可食用包装膜的制备方法，其特征在于，步骤（1）中所述加热其温度为30-100℃，加热时间为1-600min。3 . The method for preparing an edible packaging film indicating food rancidity according to claim 1 , characterized in that the heating temperature in step (1) is 30-100° C., and the heating time is 1-600 min. 4 .4.根据权利要求1所述的指示食物酸败的可食用包装膜的制备方法，其特征在于，步骤（1）中所述加热其温度为80-90℃，加热时间为20-30min。4. The method for preparing an edible packaging film indicating food rancidity according to claim 1, characterized in that the heating temperature in step (1) is 80-90°C, and the heating time is 20-30min.5.根据权利要求1所述的指示食物酸败的可食用包装膜的制备方法，其特征在于，步骤（2）中所述从天然食材中提取花青素其方法为：将天然食材洗净，切块，取100 g，加入100-150 g去离子水中，打浆1-5分钟，纱布过滤，滤液过350目筛，收集滤液，10000-12000 r/min离心5-10 min，收集上清液即为天然花青素提取物。5. The method for preparing an edible packaging film indicating food rancidity according to claim 1, characterized in that the method of extracting anthocyanins from natural ingredients in step (2) is as follows: washing the natural ingredients, Cut into pieces, take 100 g, add 100-150 g deionized water, beat for 1-5 minutes, filter with gauze, pass the filtrate through a 350 mesh sieve, collect the filtrate, centrifuge at 10000-12000 r/min for 5-10 min, and collect the supernatant It is natural anthocyanin extract.6.根据权利要求1所述的指示食物酸败的可食用包装膜的制备方法，其特征在于，步骤（2）中所述从天然食材为紫甘蓝、紫薯、葡萄皮、黑莓、樱桃、茄子皮、蓝莓、红莓、草莓、桑葚、山楂皮、紫米或红小豆。6. The preparation method of edible packaging film indicating food rancidity according to claim 1, characterized in that the natural ingredients mentioned in step (2) are purple cabbage, purple sweet potato, grape skin, blackberry, cherry, eggplant skin,blueberry ,cranberry ,strawberry , mulberry, hawthorn peel, purple rice or red bean.7.根据权利要求1所述的指示食物酸败的可食用包装膜的制备方法，其特征在于，步骤（3）中所述增塑剂为甘油或山梨醇。7. The method for preparing an edible packaging film indicating food rancidity according to claim 1, wherein the plasticizer in step (3) is glycerin or sorbitol.8.权利要求1-7任一所述制备方法得到的指示食物酸败的可食用包装膜。8. The edible packaging film indicating food rancidity obtained by any one of the preparation methods of claims 1-7.

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