Causes and Prevention of Low Vacuum in Beverage Cans

The varieties that use tinplate beverages are mainly plant protein beverages, milk protein mixed beverages and juices, and fruit and vegetable juice beverages. In this field, I rarely heard of the appearance of a low vacuum. Of course, the variety of beverages is increasing rapidly. There may be some situations in which new varieties will have a low vacuum. I think it would be best to explain the situation so that everyone can participate in discussions and analysis. Before this, I will briefly discuss what happened before. The occurrence of low vacuum, in addition to the deterioration of the product, is mainly due to the leakage of the seal and the corrosion of the inner wall.

1. The corrosion of vegetable protein drinks and some dairy mixed drinks is not very corrosive. Unless these beverages have been fermented, the acidity increases and it becomes corrosive. In general, manufacturers who like to attach great importance to the color of the product and wish to not brown during the storage period prefer to use a tin can. If the preservation period is longer, the color is not the main indicator. Because these products are not corrosive, the reactions of dissolving tin and dissolving iron are relatively slow. As long as the seal structure is closed, the problem of low vacuum will not occur.

2. Juice beverages and juice-based health drinks Because of the different control standards for acidity, corrosiveness can be very different. Some products are more corrosive due to high acidity. These products, such as the use of paint cans, are prone to iron dissolution, which in turn produces hydrogen gas that causes a reduction in the degree of vacuum. Continued corrosion can result in perforation. Juices of general acidity juices, regardless of whether they are made of iron cans or paint cans, are less corrosive and do not produce low vacuum.

3. For vegetable cans with extremely low acidity, both iron cans and paint cans produce iron dissolution, which in turn leads to hydrogen expansion and perforation. The canning of such cans should be carried out in order to ensure that the tank wall undergoes slow detinitisation and thus ensures the quality of the product.

4. If there is a drop in vacuum, you should look for the following reasons:

(1) Check the pH of the product to determine if the product has become rancid, and the rancidity of the product will inevitably lead to a vacuum drop and a fat tank.

(2) Check the structure of the seal to determine if there is a leak. This is particularly important for small canneries, and is often the main cause of the drop in vacuum.

(3) Check the corrosion of the inner wall of the tank to determine if the degree of vacuum decline is caused by the corrosion of the inner wall. If the corrosion is serious, you should look for the reasons from the following aspects: K to prevent it.

a. Whether the product is effectively vented before sealing or not, and the residual amount of air in the tank is one of the causes of severe corrosion of the tank wall.

b. Check the pH of the product to determine if the tank wall is heavily corroded due to the high acidity of the product. When necessary, the acidity of the product can be moderately reduced.

c. If the pH is normal but there is abnormal corrosion on the inner wall, the contents may contain abnormal corrosion factors such as anthocyanin, sulfur and nitrate. It should be determined through analysis that these factors should be excluded as much as possible.

d. If the corrosion factor is intrinsic to the content and difficult to remove, then a dense coating iron or paint can with a powder coating, or a two-piece can made of laminating iron may be used to ensure that a low vacuum does not occur. .

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