Why do you see whey hydrolysates versus casein hydrolysates based formulas? Which one is better?

We generally see casein hydrolysates used in hypo-allergenic infant formulas for allergic infants and whey hydrolysates in hypo-allergenic formulas for at-risk infants.


Historically, hydrolysed casein was used in hypo-allergenic infant formulas, since caseins are easier to hydrolyse to non-reactive fragments due to their simpler structure. The quaternary structure of whey proteins is much more complex than that of casein and includes alpha-helixes and beta-sheets. During hydrolysis, peptide bonds are broken and the protein is split into smaller fragments. As you can imagine, the more complex protein structure of whey protects the inner structure from hydrolysis and extensive experience is required to obtain the desired type of hydrolysate. So the first hypo-allergenic infant formulas, mainly intended for already allergic infants, were based on casein hydrolysates.

However, progressive insight showed that partially hydrolysed whey protein is very effective in reducing the risk of a cow’s milk allergy in at-risk infants and may even be beneficial over extensively hydrolysed proteins in this target group, since the fragments are small enough not to induce sensitisation, but big enough to induce oral tolerance. Hydrolyzed whey also has a much better taste compared to hydrolyzed casein.

Although the complex structure of whey protein limited the use of whey protein hydrolysates in hypo-allergenic formulas for allergic infants in the past, improved technology and experience makes it possible nowadays to use whey hydrolysates in this segment. Still, we notice this market is smaller than the market of whey hydrolysate-based formulas for at-risk infants.

Blends of casein and whey hydrolysates can also be considered, to get the desired casein:whey protein ratio.