will shaking OJ kill them critters

If I have fresh orange juice that has not been pasteurized or that is not from concentrate, will shaking it daily increase the growth of bacteria (make it go bad faster) or will letting it stand increase the growth of bacteria?

Shaking it will aereate it more. I would guess it depends on how dependent the particular bacteria is on oxygen for growth.

Shaking it will distribute the bacteria more evenly, so they should grow faster (they will be more uniformly spread through the fluid and will not be competing so much for resources). I have a feeling though, that the spoilage of some fruit juices is at least partly due to enzymes.

Shaking your orange juice daily will encourage bacterial growth, but keeping it in the fridge will discourage growth.

Shaking will aerate it encouraging the growth of aerobic bacteria. As an example, when I want to quickly grow a good stinky broth of aerobes, I put a flask on the lab bench at room temp, with a stir bar. I cover the flask so that foreign bacteria are minimized. After a night, usually my lab is pretty stinky. However, I usually suspect that I have a pretty good culture to begin with. Your OJ should be pretty clean, and the refrigeration will keep growth to a minimum.

Also keep in mind that you OJ is pretty acidic. Most bacteria aren’t particularly fond of acids, so only the acidophiles are in there to begin with.

I would worry too much about it being contaminated. It’ll probably ferment (from yeast) before you get too much bacterial contamination. My advice to any one worried about bacterial contamination is: if it smells funny, don’t consume it.

OK, would shaking the OJ promote or deter the growth of yeast?

I’d just like to be the first to point out that the thread title has both “OJ” and “kill” in it, but it isn’t about ** that ** topic.

Unfortunately, the answer to that question is, neither. Yeast are facultative aerobes. What that means is they grow both with and without oxygen present.

There’s no way that shaking by hand would generate enough shear force or acceleration to kill bacteria or yeast. You might rip a few apart via surface tension forces and adhesion, but those’ll be minor effects.