How to choose safe vacuum packaged food?
It is understood that there are usually three ways to keep food fresh: nitrogen filling, vacuuming, and adding preservatives. Vacuum preservation is relatively convenient, natural and healthy.
How to choose safe vacuum packaged food? New Angle pack gives the following suggestions.
1. Observe the swelling bag
Whether the bag is expanded is the most intuitive and convenient way for consumers to judge whether the vacuum packaging of food has deteriorated. According to physical common sense, under normal circumstances, the air pressure in the packaged food bag should be consistent with the outside world or less than the outside world after vacuuming. If the bag swells, it means that the air pressure inside the bag is higher than the outside world, which means that new air pressure is generated in the sealed packaging bag. Gas, these gases are the metabolites produced by the proliferation of microorganisms, because a small amount of metabolites of microorganisms are not enough to swell the bag. Most of the bacteria or molds that may cause food spoilage (lactic acid bacteria, yeasts, aerogens, Bacillus polymyxa, Aspergillus, etc.) will produce a lot of gas in the process of decomposing protein and sugar in food. Such as carbon dioxide, hydrogen sulfide, ammonia, alkanes, etc., it is these gases that "blow" the packaging bags into balloons. In the process of food sterilization before packaging, the microorganisms and buds have not been completely killed. After the packaging is completed, the microorganisms multiply and spoilage, and the problem of swelling of the packaging bag naturally occurs.
When shopping for vacuum-packaged food, do not judge the smell of the food as a criterion. The smell of food spills out of the packaging, which means that the vacuum packaging itself is no longer vacuum, and air leakage has occurred. This means that bacteria can also "flow" freely.