Application of the hottest edible packaging film a

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. Application of edible packaging film and analysis of key performance testing (I)

at present, there are many kinds of packaging materials used in various industries with different characteristics: plastic bags are the most commonly used and low-cost, but their non degradability will cause white pollution and seriously affect the ecological environment; Although paper bags are beneficial to recycling, degradation and recycling, the cost is high; As a packaging material in direct contact with food, cling film is prone to release harmful substances, which will enter the human body with food and affect health... In recent years, the voice of "green packaging" has become higher and higher. How to realize the "green" requirements of packaging materials has become the mainstream of packaging research

starting from packaging materials, there are generally four ways to improve the green of packaging. If you are environmental friendly when doing experiments:

1. Use reusable and recycled packaging materials

2. Develop edible packaging materials

3. Promote degradable materials

4. Widely use paper materials. From the perspective of natural environmental protection, edible packaging materials have become an important means of promoting "green packaging" because they are made of natural edible substances and can be directly absorbed by the human body after eating

the so-called edible packaging film refers to the film with porous structure, which is formed by the interaction between different molecules with natural edible substances (such as polysaccharides, proteins, etc.) as raw materials. The frequently used plastic indicators are elongation and reduction of area. According to different materials and processes, edible packaging films can be divided into: polysaccharide edible packaging films, protein edible packaging films, composite edible packaging films, etc

in China, there are various forms of edible packaging, many of which have already been used in real life: wax, oil and gelatin coated on the surface of food and fruit can effectively slow down water loss and prolong shelf life; The glutinous rice paper coated on the outer layer of candy and cakes is made of starch such as sweet potato, corn or wheat flour. It is used to isolate food debris and prevent adhesion with the outer package. In addition, corn baking packaging and sausage casings of ice cream cones are typical edible packaging. In recent years, relevant scientific research institutions and packaging enterprises have also begun to study the preparation and performance of new edible packaging films

since the edible packaging film has been studied so carefully and has a long history of practice, why has it not been applied to industrial production and commercial applications on a large scale so far? The reasons are mainly due to its unstable barrier, insufficient mechanical strength and no heat sealing

performance analysis and testing points

barrier property is the test focus of edible packaging film, including oxygen transmittance test and water vapor transmittance test. Its performance directly affects the shelf life of packaged food. In addition, in order to have the packaging function of reasonable design, simple structure and convenient use in practical application, edible packaging film needs to meet the basic indicators of packaging film in tensile strength, elongation at break, right angle tear, heat sealing and other properties. In the production process, if we want to get good packaging effect through the high-speed packaging line, the reasonable friction coefficient is the key. In order to ensure the uniform material performance of all parts of edible packaging film, thickness control is a simple and effective solution

among these indicators to be tested, barrier property, tensile strength, tear strength and heat sealing performance are the primary test items

1. Barrier property

the so-called barrier property refers to the barrier ability of edible packaging film to penetrate materials such as gas and liquid. Regardless of food and drugs, the packaging film is required to have high barrier performance to delay the deterioration process of products and extend the shelf life. For most foods, the excessive growth and reproduction of microorganisms is the main cause of food deterioration. Cleaning, disinfection, cooking, barbecue, smoking and other links in the processing process can effectively reduce the number of microorganisms. However, due to different degrees of pollution of food raw materials and different sanitary conditions of processing/packaging, the microbial residue of food products will be affected

in the later storage and transportation, if the temperature, humidity and gas volume are appropriate, microorganisms will still grow in large numbers and accelerate food deterioration. As the last barrier between food and the external environment, the ability of packaging film to block the penetration of gas and water vapor has a very important relationship with the maintenance of food quality

oxygen transmission rate refers to the amount of oxygen passing through the sample per unit area in unit time. This index can be used as an important parameter to measure the oxygen resistance of packaging film. In the current field of oxygen transmission detection, differential pressure method and isobaric method, as two independent and typical detection methods, have their own characteristics: differential pressure method can test a variety of gases, with low cost and high success rate. Its biggest advantage is to test the "purity" of ambient gases, eliminating the impact of impurity gases on the test process, but the development of container detection technology has always encountered a bottleneck, The advent of g2/130 differential pressure vessel gas transmittance tester developed and produced by Labthink Languang (Jinan Languang Electromechanical Technology Co., Ltd.) marks that this technical difficulty has finally been overcome; The detection object of isobaric method is expanded from membrane materials to containers, but the detection range is relatively limited, and it is only applicable to the test of oxygen transmittance

water vapor transmission rate refers to the amount of water vapor passing through the test per unit area per unit time under specific conditions. At present, weighing method and sensor method are the two main detection methods. Weighing method has a long history and is the arbitration method of moisture permeability detection, but the operation is complex and the test time is long. Now this method has been significantly improved. The latest weighing moisture permeability instrument - w3/031 water vapor transmission tester has been controlled by microcomputer, which can automatically affect the dynamic test of crop growth and development, and the setting of multiple moisture permeability cups greatly improves the test efficiency; Sensor methods include electrolytic sensor method, infrared sensor method and relative humidity measurement method. In terms of test efficiency alone, the sensor method is slightly better

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