Agree 100% that this must be a controlled process if done at home; sterilisation of all containers and utensils, using one way breathers etc, things can go wrong very easily if unknowingly allowed . Done well with care and attention, it is well worth the extra effort in my experience. Fermentation and pickling are commonplace where my wife is from, the UK is slowly (as with everything) coming round to the process..
Think of it as a way of liberating the amino acids that form to make peptides and proteins, humans do this process in an extremely low ph environment in the gut, relying on trillions of microbes to break down these proteins and to excrete hormone's that serve to repair and maintain the biological system, whereas the carp has a far simpler, and shorter GI tract that whole foods can and do pass straight through, often seen on the mat or sling. Anything to help the absorption of amino acids can only be a good thing of course. It surprises me when a known angler states carp are stupid because they eat there own poo, he clearly missed that day at school.. Cooking hemp is not quite at the same level of natural processing even though it can produce fantastic bait..!
The other thing is what the resident gut microbe balance is, which is a direct result of what we eat, the same goes for fish. Humans can have a wildly varied gut microbiome, some good some bad, often pretty poor if heavily processed food, beer, (alcohol in general) and fizzy pop etc are consumed regularly, leading to increased levels of communities of unwanted bad bacteria which will excrete the wrong substances for good health and lead to illness over time. I have a 56 page document on my own gut balance, something I was far more keen to get the results from than my A levels.. We should consider the same ideals for bait, as a long term food source especially, and avoiding any preservatives in my opinion is high on the list of priorities. None of my own baits use any preservative, natural or synthetic, including hookbaits even though (and before someone points out) they are not consumed..