>Food is eaten in our stomachs by bacteria. If the bacteria in our stomachs can’t (or won’t) eat something, that means it’s not digestible.

Both of these are false. Bacteria are not needed for the proper function of the human stomach (or the small intestine). The human body produces digestive enzymes, HCl and bile (and maybe bicarbonate) which combined will digest most foods without any help from bacteria.

Bacteria are needed in the large intestine to convert fiber into short-chain fatty acids (SCFAs), but a person can live for many years without any of these SCFAs' being produced in the large intestine, although the person probably would be less healthy.

Generally you're either killing _all_ of the bacteria the sealing the product to prevent new ones entering, or creating an environment that's too hostile for them to live (environments high in salt, sugar, acid, or fat, or low in moisture, all make achieve this)

Also, our stomach is full of acid, the purpose of which is to kill bacteria. Later on, in the intestine, you have a colony of microbes.

Pickled or fermented food is very healthy, and shelf stable. We've been doing that for millenia to preserve food.

It's not as simple as you suggest.

But that's not really true. Humans have for thousands of years tried and succeeded to make food not palatable to bacteria. Drying stuff is comparatively simple, but salting, smoking it, by either adding acid or fermenting (which makes the bacteria produce the acid that inhibits them), by adding alcohol (or again, letting the bacteria produce the alcohol), by introducing organisms that produce bactericides - namely fungi (cheese mold) that produce antibiotics. By adding sugar. Honey is shelf stable beyond your wildest dream. There's a lot of ways to get things shelf stable that use natural ingredients only and are - at least in reasonable amounts - perfectly safe to eat.

Your body will do a lot of work on food before it is in the end absorbed. It adds enzymes that break up molecular bonds. It will use acid on it. You will mash it with physical energy. It will be watered down and mixed and in the end, the molecules will be absorbed by your body.

That doesn't mean that you should eat just about everything, that's not true. But I believe making the connection via "bacteria won't eat that, it's not good" doesn't make a good point.

We don't digest food exclusively with bacteria. They play a role, of course, but our digestion is done through things with hydrochloric acid and various enzymes produced by the stomach. The bacteria in our stomach is pretty much strains that can both survive the acidic environment and can consume things we cannot digest at all. Various fibers, for example. They help as they consume it and shit out stuff we can digest. Often the things they consume that are indigestible to us are the result of our own breakdown of other compounds; making the process symbiotic.

Also, the environment on a kitchen counter is wildly different than the environment inside out stomach, so airborne bacteria- even if we were to presume these were the exact same kinds of bacteria present in our stomach - being uninterested in foods in the open air doesn't really translate to the idea that the food is indigestible. Many gut bacteria rely on us to break down foods into the things that they can digest, so a colony couldn't start on the surface of the same food(s) in the open air.

I am not very well read on this topic, but it seems like there are other ways to make shelf stable food that doesn’t necessarily make it harder to digest. For example high salt or sugar contents, or removing most of the water. These make it harder for bacteria in the environment but don’t pose a barrier when mixed up in your gut.

Granted, you can’t do that with shredded cheese. which is why it has to be refrigerated and will eventually go bad.

>But how do they make shelf stable cheesy / creamy products?

pasteurization and keeping further bacteria out is one way to do it

Yeah no this is nonsense powdered by pseudoscience and a wrong premise. Food is not eaten in our stomachs by bacteria, please look up some basic biology and consider correcting your post accordingly. At least your incorrect post isn't dangerous per se.

That sounds like an extremely pseudo-scientific book. For the real explanation, see https://en.m.wikipedia.org/wiki/Water_activity