Whey hydrolysate is whey protein that has additionally been broken down by enzymes into smaller protein fragments known as peptides. This process is called hydrolysis and partly imitates what happens in the digestive system anyway before the body can absorb protein.
In practice, whey hydrolysate is associated with particularly fast absorption, because pre-digestion has already partly taken place. In taste, hydrolysate is often more bitter than concentrate or isolate, which is why manufacturers often flavour it more strongly. In the nutrient balance, hydrolysate counts towards daily protein intake like other forms of whey and differs mainly in processing and price.
A comparison with less heavily processed variants can be found in the entries Whey protein and Whey isolate, and the guide Mixing a protein shake properly gives practical tips on preparation.
