Does the volume of air in an air tight container affect food shelf life?

Question

I'm specifically talking about storing tea bags here, but equally any other dried foods. I'm trying to switch to buying certain things in bulk, so I'm trying to understand some basic principles.

I understand that once I put foodstuffs in an airtight container, the air inside the container contains bacteria and mold floating in the air.

When the container is full of food, there is obviously still air in there, even is it is small. And as you consume the food product, the air volume gets larger.

So my questions are:

1. Will a foodstuff, such as tea bags, go off or degrade quicker in a larger volume of air as the volume increases or does it not make much difference? I could buy two or more smaller containers so that the air volume is much smaller once food is removed, or I could buy one large one.

2. If there is air in the container with bacteria and mold anyway, what benefit does an airtight container provide?

Answer 1

Yes, but it’s not so much about mold and bacteria, but about oxygen.

Oxygen availability results in deterioration of some foods via chemical reactions. Some packaged foods, especially those intended for long term storage (such as disaster preparedness meals) will either vacuum seal the package, ‘oxygen absorber’ packets to reduce this problem, fill the package with nitrogen to push out any oxygen, or a combination of these.

There are hard sided containers that have a one-way valve on them, so they can be connected to a vacuum to remove air, but this can cause problems for some foods (marshmallows are a classic example, as they will expand to fill the space).

One way to deal with your issue is to use more than one container. You keep a smaller container that you’re opening for regular use, and then a larger container that only gets opened when you need to refill the smaller one. This reduces the number of air changes that the food is exposed to before it’s used up. To reduce it further, you can use multiple smaller containers, fill them as full as you can, then use up the remainder (not entirely full one) first.

Answer 2

1. Degradation

Having a larger container with more air volume does not do much to the foodstuff inside. Especially if it is "dry" like tea bags, noodles, rice, etc. (A little different would be fresh food in a container for storing in the fridge, of course).

Tea for example is best stored in tin cans. The air tightening is only needed, if you do not like the odor/smell of the tea lingering in the air. Tea will stop smelling after long periods exposed to air, which might affect the taste (connoisseurs will care).

Keep in mind that plastic containers tend to take on smells (tea) and always stays smelling like that, even after washing thoroughly. Metal boxes (stainless steel) does not take on smells or at least is easily neutralized with a little water and dish soap. Glass containers work also nicely for rice, noodles, etc.

2. Usefulness

There are multiple benefits for containers:

• prevents insects like flies, moths, spiders, ... reaching and infesting the food
• allow easier stacking and storage
• can be labeled, sorted by date of expiry, whatever you like
• keeps odor/smell inside (see above in case of tea)
• prevents moldy/spoiled food inside from spreading over to other food/containers. So you lose maybe only one container, not the whole stock. Considering the right size can greatly help reduce damage in such a case, but is a trade-off in storage space / cost etc. of course.
• prevent food from getting humid or wet in the worst case.

For example, I use 5 liter airtight plastic containers to store multiple (2-3) packets of rice, noodles, dried beans etc. in it (separated per type). Mostly to fend of vermin/insects and for easier storage.