I have been updating my list of hydrolyzed proteins by weight, you can find the new list in this old post.
I also learned that hydrolyzed collagen and gelatin (partially hydrolyzed collagen) contain significant concentrations of amino acids which are beneficial to hair strength - many of which are found naturally in high concentrations in the cuticle of hair, already serving a functional role. Those include Proline (not found in most other hydrolyzed proteins), Glutamic acid, Valine, a little Cysteine and Histidine.
© Science-y Hair Blog 2013
Hydrolyzed collagen adsorbs (temporarily bonds to) hair, increasing it's resistance to breaking under tension. The more concentrated the collagen in a formula, the more will bond to hair - at least up to a point. The smaller the collagen molecule, the better it bonds to hair - so hydrolyzed collagen will bond to hair better than and longer-lasting than gelatin you can buy over the counter. If your hair is damaged (on the ends, for example) it will bond with more collagen protein than un-damaged hair.
So if you like the gelatin protein treatment recipe on this blog and you want it stronger, increase the gelatin without increasing the water. If you want it less-strong, decrease the gelatin and keep the water the same, or increase the water and keep the gelatin the same.
©Science-y Hair Blog 2013
Collagen binds water to your hair - not just attracting it like a humectant, but holding it there. And it does that better at a pH of 5 than a neutral pH.©Science-y Hair Blog 2013
You may note I have altered the gelatin protein treatment recipe because as it was written initially, it was too acidic. I strongly encourage you to invest in some pH test strips when adding acids to avoid damaging your hair.©Science-y Hair Blog 2013
You can get a boost of collagen protein from the shampoos and conditioners on the "Product by Category" page - scroll down to the list of protein-containing shampoos and conditioners. The shampoos listed are "sulfate-free."