canningfood-preservationfood-safetystorage-methodvacuum
For products that start out shelf stable but are labeled "refrigerate after opening," I'm wondering if it's possible to safely return them to their shelf-stable status to save refrigerator space. A few specific products come to mind: olives, maple syrup, salad dressing.
For example, could a vacuum sealer and a sterilized jar work? Or does exposure to germs in the air compromise the food requiring refrigeration?
If you want to shelf store the cooked legumes in plastic, you need to buy boilable pouches
They are a great space saver, and somewhat environmentally friendly as the oil/energy required to make one glass preserving jar can make 50 to 100 of these bags. And how many preserving jars survive 50 times without breaking!
You will find plenty of sources on the Internet, typical prices $50 to $200 per 1000
The process varies from each bag supplier and vacuum system, but is similar to normal home preserving
If you get the foil lined (light proof) pouches they will preserve food for many years
Example suppliers caspak pacrite
This process is popular in NZ and AU, but as I have just discovered, not so in the USA? So it maybe easier to order from here
The energy, weight, and space saving of plastic pouches is significant
The major protein in cow's milk, casein precipitates at pH 4.6. It matters very little which acid you use to get to 4.6, casein will still precipitate. pH 4.6 is about the same acidity as canned beets, a food not known for its tartness, so you won't achieve a very sour flavor before things start curding up on you. Adding emulsifiers could help some with the isoelectric precipitation, but emulsifiers have flavors too, and you'll have to add them at a not insignificant fraction of the protein (casein) concentration.
For shelf stable chocolate milk, I'd go with a mix of powdered milk and cocoa powder; just add water. All the storebought room temp chocolate milk products I've seen are ultrapasturized or similar.
Best Answer
Exposure to germs is the problem, once you open these they are exposed and the clock starts. If you vacuum seal you are vacuum sealing the germs in with the food, and not taking steps to kill the pathogens. Pouring into a sterilized container again just puts contaminated food into an uncontaminated container.
The only way to make them shelf stable again would be to process them. You could vacuum seal and then pasteurize the food inside for example, or re-can and pressure-cook. This takes a lot of time and energy, and each time you do it you lose quality.