High barrier packaging materials are widely used i

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High barrier packaging materials are widely used in the food field (Part 2)

II. Milk powder

milk powder is the most important solid dairy product in China's dairy market at present. Although its storage performance is better than liquid milk, it is also a perishable food. Therefore, milk powder packaging is an important means to maintain the quality of milk powder. The quality requirements of domestic milk powder enterprises for milk powder packaging are mainly reflected in ensuring that milk powder has a long shelf life, anti-oxidation, moisture-proof caking, no odor, and no light. In order to meet these requirements, the enterprises producing packaging should, on the one hand, produce in strict accordance with the process requirements, on the other hand, carefully select packaging materials to ensure that their performance meets the requirements. Barrier is a very important aspect

1. There is no shortage of oxygen resistance, water resistance and odor resistance

milk powder is one of the five series products under Yashili. Manager Li of the company's quality control department believes that in the food field, milk powder is a class of products with very high requirements for the barrier of packaging materials, and its requirements for packaging materials are mainly reflected in oxygen resistance, water resistance and odor resistance. This is because milk powder contains a lot of fat. If it is in too much contact with oxygen, the fat will be easily oxidized, resulting in clam flavor. Similarly, if the milk powder packaging material does not have a very high water resistance, the milk powder in the package is likely to agglomerate due to dampness, which will seriously lead to the breeding of microorganisms. In addition, milk powder is also very sensitive to peculiar smell. Serious foreign smell will change the flavor of milk powder, and even endanger the health of consumers. Therefore, in addition to having a strong barrier to external peculiar smell, the packaging material itself should not have any peculiar smell that affects the flavor of milk powder

2. The three aspects of material selection, inflation and detection cannot be ignored

at present, the commonly used materials for plastic composite packaging of milk powder include BOPP/PE, PA, aluminum foil and aluminum plating. Due to the short shelf life of milk powder, the third Automotive Plastics Technology Forum was successfully held a few days ago, and Popp/PE materials are gradually being eliminated from the market. Aluminum foil and aluminized composite packaging have become the mainstream form of milk powder packaging because of their superior performance, while the relatively high cost of PA hinders the further expansion of its market share. At this stage, aluminum foil and wmpet are widely used in milk powder packaging? Aluminum plated polyester film? snow. Milk powder composite packaging structure usually has three or four layers. For example, PE/aluminum foil/PE packaging is widely used in domestic milk powder enterprises at present. It should be pointed out that the selection of packaging materials should not only consider the barrier to oxygen, moisture, odor, light, etc., but also take into account other properties, such as heat sealing performance and mechanical strength of inner layer materials, It is also necessary to control the pollution of the precipitation of inner membrane additives to the quality of milk powder and the inability of milk powder to be poured out due to the adsorption of milk powder on the inner membrane caused by excessive static electricity

for milk powder enterprises, the shelf life of products has always been a common concern. In order to obtain a longer shelf life, high barrier packaging materials are certainly a very important aspect, but they are also closely related to whether the packaging bag is inflated. According to manager Li of Yashili quality control department, Yashili nitrogen filled milk powder with high barrier packaging materials has a shelf life of up to 18 months, while the shelf life of milk powder without nitrogen filled packaging is generally only about 1 year

for milk powder enterprises and packaging production enterprises, there is another point that must be paid close attention to, that is, packaging testing. For ordinary flexible packaging, solvent residue is inevitable, because printing inks and adhesives contain certain solvents, and some solvents need to be added in production to adjust printing suitability and dilute adhesives for coating. Some of these organic solvents, such as inks, adhesives, solvents, etc., used in the printing and packaging production process will remain between the composite films. With the passage of time, they are likely to migrate from the surface of the film to the milk powder, causing it to deteriorate and taste. Therefore, in addition to using high-quality inks, adhesives and high barrier packaging materials, milk powder packaging manufacturers should also strengthen the detection of residual solvents in packaging materials for high-quality, fine and sharp hydraulic systems. At present, Yili and other domestic famous enterprises have done a very good job in this regard. For example, Beijing Debao shangsan packaging and Printing Co., Ltd., the packaging supplier of Yili milk powder, has adopted extrusion composite process and strict testing of packaging, The total amount of residual solvent in Yili milk powder packaging is controlled below 3mg/m2, which is far lower than the national standard of 10mg/m2. In terms of oxygen and moisture permeability of packaging, domestic enterprises currently use more accurate electricity analysis method

III. snack food

1. Jelly: the innovative combined application of EVOH, LLDPE, etc. has been recognized by the industry.

Mr. Luo Wenbin of Guangdong Xizhilang Group Co., Ltd., the largest jelly manufacturer in China, said that jelly products have many flavors and a shelf life of up to one year, so the oxygen resistance of packaging materials is particularly important. Once oxygen enters the packaging, it is very easy to change the taste of products, At the same time, the shelf life will be greatly shortened. Mr. Luo believes that although PVDC and other materials have high barrier properties, they can not fully meet the requirements of products, so at present, the aluminum-plastic composite barrier diaphragm is widely used by Xizhilang

according to insiders, at present, many enterprises have more or less added a certain amount of preservatives to their products in order to extend the shelf life and shelf life of jelly. Although it is allowed by the national food hygiene department to add a small amount of preservatives to food at present, safety, hygiene, health and nutrition have become the general trend of the development of the domestic food industry and market consumption. Can high barrier packaging materials make a breakthrough in this regard, It has become a new topic for enterprises in the industry. Xizhilang has made a useful exploration in this regard. The cover film of Xizhilang "Crystal Love" jelly launched by Xizhilang uses EVOH, metallocene LLDPE and other resins for innovative combination. We believe that after CO extrusion blow molding, it has the characteristics of high barrier, transparency and good opening, effectively extending the shelf life of products, and therefore won the second prize of the first "DuPont China Packaging Award" food category

2. Chocolate and pet food: packaging inspection puts on the second safety suit for food packaging

Mars, Nestle, Cadbury and other internationally renowned food enterprises have always had strict requirements for food safety, and have always attached great importance to the selection of packaging materials and packaging inspection, setting a good example in the industry. They usually require that packaging and printing enterprises must be equipped with water permeability, oxygen permeability detectors, tension meters, hue gas spectrometers and other testing equipment, or cooperate with authoritative testing departments to ensure the safe and effective application of packaging materials. At the same time, the enterprise also has its own special packaging department, which is responsible for the evaluation and testing of packaging

Miss Sun of Cadbury (China) Food Co., Ltd. believes that the importance of food safety is self-evident for both consumers and the company itself. Chocolate has very high requirements for the hygiene and barrier of packaging materials. In order to ensure its safety and hygiene, Cadbury usually attaches great importance to the selection and testing of packaging materials in addition to strictly controlling the production process. The company will require packaging material suppliers to provide authoritative testing reports, and must fully meet the standards in terms of moisture permeability, oxygen permeability, hygiene indicators, heat sealing strength, thickness, etc. Even so, The company also personally carries out packaging tests under simulated harsh environments and various conditions, and advances the preparation of various packaging tests, so as to truly prevent disasters before they occur, thus effectively ensuring the safety and reliability of food packaging

although pet food is not a snack food in the strict sense, the packaging inspection can not be ignored. For example, if the packaging barrier of dog food produced by alfen food under Mars is not good, it will cause the infiltration of ink, adhesive and external fragrance. However, dogs are extremely sensitive to smell. Even if it is a little peculiar smell, it may refuse to eat, which will make the product difficult to continue to sell. These little odors are often difficult to make a correct judgment only by the smell or experience of the inspectors. In this case, it is necessary to make a correct judgment with the help of professional detection instruments such as hue gas spectrometer

how to scientifically select high barrier materials

1. Clarify the misunderstanding of high barrier packaging materials

the relevant person of Jiangsu Qionghua High Tech Co., Ltd. believes that at present, domestic food enterprises still have some misunderstandings about high barrier packaging materials. He reminds the majority of food enterprises that they must have a scientific understanding of this. For example, when it comes to high barrier packaging materials, people usually mention aluminum coating, but strictly speaking, aluminum coating is not a high barrier material. Although the aluminized film has better water vapor barrier performance than its corresponding PVDC coated film, as a high barrier packaging material, we should also consider the barrier to oxygen, fragrance, etc. in this regard, the aluminized film with an aluminized thickness of only about 300A is far less than PVDC coated composites. For another example, although PA with good oil resistance has a certain oxygen barrier ability in dry state, its barrier performance decreases significantly with the increase of ambient temperature, and PA's fragrance retention and taste separation ability is relatively low

2. Precautions for the use of high barrier packaging materials

Mr. Li Jianwei of Mitsui introduced some aspects that should be paid attention to when using high barrier packaging materials. He pointed out that although most of the high barrier materials have excellent barrier properties, these materials also have some use defects. For food enterprises, they should pay attention to them when using, such as EVOH, In fact, it is only suitable for cooking below 100 ℃, and many food enterprises need to place the products at above 120 ℃ for sterilization for 30 minutes or longer. In this case, if EVOH soft packaging is used, special attention should be paid, because EVOH will temporarily reduce its gas resistance after boiling, which is a temporary phenomenon caused by moisture absorption during boiling, However, with the passage of time and the volatilization of water, its gas barrier performance will soon be restored

relevant people in Jiangsu Qionghua also pointed out that in addition to strict requirements for oxygen and steam, many foods should also pay close attention to odor prevention and oil resistance. For example, milk powder, biscuits, candy, cakes, which are very important for the maintenance of special flavor, while the cutting of the other two samples requires strict control, and the seasoning package, oil package and other foods of instant noodles, if the high barrier aroma preservation packaging is not used, the product quality and flavor will easily decline sharply with the extension of storage time, shortening the shelf life and making it difficult to sustain sales, thus bringing unnecessary losses to the enterprise. In addition, the use of packaging materials must also take full account of the characteristics of the inner food. For example, BOPP/PE composite film is feasible for the outer packaging of instant noodles, but it is completely useless if it is used as the packaging of biscuits and candy. This is not only because its ability to block moisture and gas is slightly insufficient, but also because it has no fragrance retention ability at all. For food such as cookies and candy, if its packaging does not have sufficient fragrance retention and odor separation ability, the taste when eating will definitely be greatly reduced

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