I've been looking for the most convenient way to preserve stock at room temperature. It seems that Bovril preserves just containing a 14% of salt, while every powdered product contains 50% of salt. I was wondering why so much salt is needed for powdered stock and if it's safe to try this kind of preserve at home.
If you are starting with your own beef stock, the best way to preserve it long term is to freeze it. If you are lacking on freezer space, reduce it by half...or even three quarters, then freeze. You can add the water back when you thaw and use. If you concentrate it a lot, you can even freeze in ice cube trays for convenience. This will be far superior to any bullion cube (like Bovril, which has very little relationship to stock, and BTW, 14% is a lot of salt).
These commercial products are using dehydration, salt, and other ingredients to create an environment that is inhospitable to pathogen growth. The flavor likely does not even come from stock. You are probably not able to reproduce the industrial process that they follow.
I would suggest your time is better spent making a good stock, and following my suggestion above. Your food will be better because of it.
You can preserve liquid stock at room temperature using pressure canning, where you put your jars in a large pressure cooker to raise the temperature of the food you are preserving high enough that it will kill all foodborne illnesses. This is how low acid-low salt foods like tomatoes and beans are typically canned and jarred. Pickles and jams can be water bath jarred because they have enough acid, sugar and salt to act as preservatives. You can't water bath stock because it doesn't have enough salt, and if you added enough it would be absolutely inedible.
I would first reduce the stock down to make a concentrated stock before canning, it's less work overall - as you get more stock per jar and can use smaller jars there's fewer batches. Add to that it takes less shelf space.
I would only can stock if freezing is not an option, if it is I'd use the method @moscafj has outlined, it's faster and far easier.
5@Hobbamok All I know about canning is what I've picked up from skimming the never-ending stream of canning questions on this site, but I don't think the oven can achieve the same result as pressure canning. You may want to review what you do to ensure it is truly a safe process.– dbmag9Sep 23, 2022 at 9:49
2@dbmag9 yeah, but what I've picked up from this site's meta board (and regular answers) is that everyone here is trying to be an industrial mass food producer safety wise, and I am frankly not. Bad broth is pretty risk free in that you notice if it's bad, and glasses either go bad or they don't. yes, this comment is not FDA approved and therefore in violation of this site's rules but so is gorgonzola cheese. Valid point of yours however for the more cautious folk.– HobbamokSep 23, 2022 at 11:07
4@Hobbamok comparing gorgonzola cheese, which passes several pathogen safety hurdles, to your oven process is reckless. "Canning" in the oven does not eliminate the risk of spore forming pathogens. It is not based on a conservative, governmental policy, and it is not true that everyone here is trying to be a mass food producer from a safety perspective. It is based in science, and that science is the same whether cooking at home or in a factory. You are risking your health, and the health of those you serve. You do you, but I strongly advise anyone reading this to avoid this practice.– moscafjSep 23, 2022 at 13:00
5I see where you are coming from @Hobbamok, although I have a different interpretation. Food safety study is a science, and there are people in labs who spend their lives coming up with guidelines based on measurable date. We are just acknowledging that they know far more about it than we do. Now, I don't follow their advice at all times, I eat leftovers past recommended dates and cook burgers medium rare, however I do that knowing there is a small amount of risk involved. With canning the potential for risk is high, so I follow solid practices, which does not include baking.– GdDSep 23, 2022 at 13:01
1@Hobbamok The particular risk is that your belief that you can always tell when a jar has gone bad is only true for some things that make them go bad. If you haven't run into the other sort yet, you've been lucky. If you do, you won't be around to post about them afterwards, most likely. I reuse lids if they are in good shape, against more paranoid advice, but there a seal failure is a seal failure, and obvious. A jar not processed at adequate time and temperature is prone to more subtle ways of going bad. And an oven is not a pressure cooker.– EcnerwalSep 24, 2022 at 17:27