Bet you they do😉
If you put a flavour in a bait, it has the base solvent, which is in many cases a preservative. If you put in a powdered ingredient, it likely contains either an anti-caking agent, or an ingredient to slow down or prevent it going rancid, they are preservatives.
Even basic sugar and salt are forms of preservative.
Actually it is, to quote myself "Hydrolysate is a posh way of saying more digestible or usable protein".
If you copy my statement above, go to Google and then type in 'is' followed by pasting my wording above you will get the answer "Yes, basically it is", and then a scientific process review.
I would not have said it without knowing what I was saying, and buzzwords get put into baitmaking just like in convincing humans that isotonic, hydrolysates, are better for you than a standard diet.
However, for the average person, regular protein is digested and used just fine. Hydrolysates often come with a much higher price tag, so you are mostly paying for the speed of absorption rather than a magical increase in overall nutritional quality.
Then you have potential side effects of hydrolysates, poor palatibility, bloating, gas, diarrhoea or constipation and funnily enough, many contain preservatives, sugar alcohols, thickening ingredients and artificial sweeteners.