Aluminum foil for food is a flattened metal aluminum product tool, which can be used in the kitchen to cook, hold food, or to make some simple clean materials.
The aluminum foil packaged food on the market is generally heat-resistant and storage-resistant. Most of the aluminum foil used for food processing has one side bright and the other side gray. The aluminum foil used for food can be used to wrap food on both sides. It is usually recommended to wrap the food with a bright surface to improve the heat conduction effect.
Why aluminum foil is used for food packaging bags? This is because metal aluminum will be oxidized by oxygen, forming a dense oxide Al2O3 protective film on the metal surface to prevent oxygen from continuing to oxidize metal aluminum. Of course, packaging bags made of aluminum foil use this layer The dense protective film can well isolate the outside air from entering the bag and play a role in preventing food from being oxidized and deteriorated.
On the other hand, aluminum foil has good ductility, excellent barrier properties, strong corrosion resistance, and good printing adaptability. Instead of preventing food from reacting with oxygen.
Aluminum foil is used in food packaging bags, which has good barrier properties. Aluminum foil has a very low oxygen transmission rate and can effectively block the gases in the air that can easily deteriorate food, such as oxygen. In addition, the aluminum foil is opaque and has good shading properties to prevent certain foods from being discolored or deteriorated due to light. The aluminum foil itself has very poor corrosion resistance and is easily corroded by acid or alkaline substances.
1. Aluminum foil bumps
▲Aluminum foil bumps refer to the damage on the surface or end face of the foil after it collides with other objects during transportation or storage. Most of the bumps are caused by carelessness in aluminum foil packaging.
▲The surface of the aluminum foil is in contact with the surrounding medium. After the chemical reaction or electrochemical reaction occurs, the defect produced on the surface of the aluminum foil, the surface of the corroded aluminum foil will lose luster, and gray corrosion products will be produced in severe cases. The corroded aluminum foil will have a great impact on the aesthetics of the products produced by the terminal.
3. Surface bubbles
▲Aluminum foil with surface bubble defects will have irregular round or strip-shaped cavities on the surface of the foil; the raised edges are round, asymmetrical on both sides, and the distribution is irregular. Unbalanced forces are likely to cause a shutdown and a break.
4. Dark side stripes
▲Dark surface stripes mostly appear on double-coated products. The dark surface has obvious light and dark striped patterns along the rolling direction, which affects the appearance.
▲There are many situations that can cause imprints on the surface of the aluminum foil, such as defects on the surface of the roller or guide roller, or dirt such as metal shavings, the surface of the sleeve or tube core is not clean or partially smooth and convex, or the foil is coiled Foreign matter stuck on the surface, etc. The surface of the foil with imprints generally has single or periodic depressions or protrusions, which are easy to distinguish.
▲Common oil stains on aluminum foil are formed after annealing, and they are generally pale yellow, brown, and yellowish brown spots.
7. Degreasing is not clean
▲Check whether the degreasing is clean or not. Generally, after annealing, the degreasing level is tested by the water brushing method. If it does not reach the level specified in the water brushing test, there may be oil on the aluminum foil.
8. Cracked edges
▲The phenomenon that the longitudinal edges of the aluminum foil surface are cracked, called cracked edges. In severe cases, obvious gaps can be seen at the edges.
9. Poor board shape
▲As a result of uneven deformation, the surface of the foil has local undulations, which is called poor shape. According to the location of the defect, it is divided into middle wave, side wave, two-rib wave and compound wave. The side waves are called side waves, and the middle waves are called middle waves. Both are called compound waves. Neither the middle nor the sides are called two-rib waves.
▲A single sheet of aluminum foil roll is not easy to open. When multiple sheets are opened, it is in a hardened shape, and the free falling length of the product cannot meet the standard requirements. In severe cases, the single sheet cannot be opened, and the adhesion of aluminum foil will seriously affect product production.