Canned Preservation Principle (5) - The Generation of Vacuum in the Can
Published date and time: 2021-06-25, 23:00
Date and time of modification: 2021-06-25, 23:00
Author: Food-Men
This article introduces the purpose and method of vacuum generation in cans, possible reasons for insufficient vacuum, for reference by food manufacturers.
1. How to Create the Vacuum in the Can?
1.1 The vacuum generated by machinery: the can container is kept in a closed vacuum chamber of the sealer during the sealing process. At this time, the air in the container is evacuated by the vacuum pump, and then the container is sealed. This method is suitable for solid foods, such as canned meat and bones. This kind of equipment includes: FK-30 Automatic Vacuum Seamer or Sealer for Cans Double Seam, Plastic Bag Vacuum Sealer.
1.2 The vacuum generated by water steam: inject steam into the top space of the container that has been filled with food to exhaust air, and then seal the container. When the steam cools in the container, it turns into water, and the container creates a vacuum. This method is suitable for liquid or part of solid food. This type of equipment includes: FMG-6H Automatic Cans Double Seam Seamer or Sealer.
1.3 The vacuum produced by hot filling: Fill the canned container with hot food. At this time, the air in the can container is heated to expand and is evacuated out of the container, then seal the container. When it cools, there is less air in the container, creating a vacuum. This method is suitable for liquids. Such equipment includes: beverage filling production line.
2. The Purpose of Creating a Vacuum in the Can
Reduce food oxidation; inhibit microbial growth; reduce excessive expansion of cans during sterilization and heating.
3. Possible Reasons for the Insufficient Vacuum
3.1 Container leakage: For obvious container leakage, it can be easily detected and discovered at the time of production. We should pay more attention to "chronic leakage". If the container has capillary leakage holes and these small holes are blocked by liquid food, the degree of vacuum will drop very slowly. It is not until a few days later that the value of the vacuum drop can be detected and discovered.
3.2 Microorganisms in food containers produce gas: one situation is: the container "chronic leakage", the liquid food blocks the small leakage hole of the container, but the outside microorganisms can still penetrate into the container through this small hole, grow and produce gas. Another situation is: due to insufficient sterilization, microorganisms in the container grow and produce gas. In these cases, the vacuum in the container drops very slowly and cannot be detected and discovered until a few days later.
3.3 The acidic food in the metal container chemically reacts with the metal of the container to produce gas. In these cases, the vacuum in the container drops very slowly and cannot be detected and discovered until a few days later.
3.4 Other reasons: Insufficient filling temperature, malfunction of vacuuming equipment, the headspace of the container is too small, etc.
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