May. 24, 2022
There is a wide variety of equipment for vacuum packing food at home. They vary widely in technical complexity and price and are often called vacuum packaging machines or vacuum sealers. These machines can extend the storage time of refrigerated, dry and frozen foods. However, vacuum packaging is not a substitute for heat treatment of home canned foods.
Vacuum packaging is also not a substitute for refrigerator or freezer storage of foods that would otherwise require it. In fact, vacuum packaging increases the problems associated with storing these perishable foods (which are unstable at room temperature and require refrigeration).
There are many precautions that must be taken when vacuum packing perishable foods for refrigerator or freezer storage. You must assume that perishable foods have a potential risk of pathogenic contamination. And, when frozen foods are ready to be thawed and used, steps must still be taken to minimize the risk of microorganisms in the food. Similarly, perishable foods must still be stored refrigerated or frozen after being packaged in a vacuum or partial vacuum environment.
Oxygen in the ambient air does promote certain reactions in food that can lead to a reduction in quality. For example, the presence of oxygen can promote oxidative rancidity and certain color changes in fats in foods. Therefore, removing oxygen from the environment will preserve certain quality characteristics and extend the shelf life of the food based on quality.
However, removing oxygen from the surrounding environment does not eliminate all possibilities of bacterial growth; it simply changes the nature of what can happen. In fact, it is the growth of spoilage bacteria that is most likely to be eliminated. Bacteria that usually destroy the quality of food in obvious ways (smell, color, consistency, etc.) like to have oxygen in the environment. If able to multiply on food, these spoilage bacteria can let you know if the food is spoiled before it can make someone sick. In the almost oxygen-free environment created by vacuum packaging, spoilage bacteria do not multiply as fast, so the loss of food quality is slowed down.
However, some disease-causing (disease-causing) bacteria, such as those in low-oxygen environments, multiply well in vacuum-packaged foods. In fact, some pathogens multiply even faster than they would if they were present if there were no competition from spoilage bacteria. These bacteria also usually do not produce significant changes in the food. In a vacuum-packaged environment, foods may become unsafe due to the growth of pathogenic bacteria and there are no indicators to warn consumers; without sufficient oxygen, bacteria will also usually multiply and destroy the food in order to make it unattractive (odor, sliminess, etc.).
For example, if the package presents anaerobic (lack of oxygen) conditions, Clostridium botulinum (a very dangerous pathogen that can cause fatal botulism under certain conditions) grows at room temperature in low-acid moist foods - if bacteria are present, the course. Without competition from spoilage bacteria, multiplication is much easier. 38-40 degrees F refrigeration becomes a critical step in storing low-acid vacuum-packaged foods that are unstable at room temperature (do not keep) (e.g., properly canned). The actual temperature of the refrigerator and the temperature at which the food is stored is critical to maintaining the safety of this product. If the food is not packaged under vacuum, oxygen in the environment will provide some protection against C. botulinum growth and toxin development in the package.
The removal or reduction of oxygen in the storage environment does help extend the storage quality of dry, non-perishable foods such as dried fruit or crackers. Products like these have a low enough moisture content to prevent bacterial growth.
Double Chamber Vacuum Packing Machine
However, proper thawing under conditions that minimize bacterial growth (such as refrigeration) is essential. If the package remains closed during thawing, you still have a vacuum environment in which pathogenic bacteria can be active if the temperature is high enough.
There is no advantage to using a vacuum packer in combination with boiling water or pressure canning of food products. Jars processed in either canning jar will create enough vacuum for safe, stable storage at room temperature. They also have the added advantage of a heating process that kills pathogenic bacteria capable of growing in that food at room temperature.
So is there a need for a vacuum packaging machine or what are the benefits of having one? One needs to ask if the amount of investment is worth the use of the equipment. Traditionally recommended freezing procedures and packaging methods, if carefully executed, will produce high quality products and considerable storage time. Storing crackers, nuts and other dry foods in sealed storage containers will also maintain their high quality for a reasonable period of time during normal use.
And, perishable foods still need to be handled carefully to prevent pathogens from making them unsafe. Keep in mind that removing oxygen from the food environment can not only solve some food storage problems, but can also lead to others. Consider how careful safe food handling practices will be followed at all times, as vacuum packaging creates very good conditions for certain pathogens to become a problem if anything goes wrong. For example, vacuum-packed perishable foods should not be refrigerated for too long - no more than 2 hours total time above 40 degrees Fahrenheit. Foods that need to be refrigerated without vacuum packaging still need to be refrigerated! Very clean hands and clean and sanitized equipment and worktops are essential when packing and preparing or using food later. Unless frozen, food should be dated and used within a reasonable storage time. Raw meat, poultry and seafood should be thoroughly cooked to the recommended temperature and measured with a food thermometer before serving. Any food that shows signs of spoilage should be discarded - if in doubt, throw it away!