Yeah the general theme is depriving microorganisms of something they need to thrive in the food environment. Like dehydration lowers water activity, refrigerati

Yeah the general theme is depriving microorganisms of something they need to thrive in the food environment. Like dehydration lowers water activity, refrigeration keeps it outside their ideal temperature range etc. Fermentation doesn't really fit with the rest under that model though. In that case you're creating a good environment for some (halotolerant lactobacillus usually) because _their_ byproducts will make it too acidic for other things to thrive. So that's fundamentally different from just trying to make it universally hostile to microorganisms. Even within a simple technique like "sealing" here it really depends on the food itself and probably local factors like seasonal humidity and temp swings. A lot of fresh foods if sealed in an airtight container can make botulism. I'm pretty informed on this subject but I don't know why that doesn't happen with the grapes here. Must just not be present on them in large amounts, or the natural yeast competes with it, or something who knows. We think of these technologies as simple because they are beyond ancient and the actions you take to use them are basic. But there is a lot going on biologically and it seems at least somewhat understudied so far.