Curds and whey. Those two words are more than a short line in a nursery rhyme. Curds and whey are the two main products of cheesemaking, as 100 pounds of milk yields 10 pounds of cheese and 90 pounds of whey. Once the afterthought of dairy processing, whey has been transformed into a valued product because we can now isolate its proteins, which are among the most complete known to man.

In previous generations, whey had two primary destinations - animal feed or, an even less valuable form, land application . . . as a low-grade fertilizer. That all changed when technology progressed and enabled processors to harvest whey's valuable components.

Through whey fractionation, we are able to isolate whey proteins by running them through a membrane. As a result, we strain out 94 percent of the water and retain its solids - mostly protein - along with some fat, minerals and lactose. As our understanding of fractionation expands, we can build more elaborate filtration plants to isolate even purer, and thus more valuable, proteins.

Whey protein is a great human food ingredient because it is easily digested and efficient at building lean muscle mass. These proteins also curb hunger by creating a feeling of fullness, excel at rebuilding and repairing muscle after exercise, and reduce age-related muscle loss.

Some dairy processors have come to believe that the value of their whey stream, when converted to higher-value whey protein concentrates and isolates, may even exceed the value of cheese. There is good reason for this opinion as whey markets are booming. Sales of sports nutrition products grew from $3.5 to $5.2 billion between 2006 and 2011, reported Euromonitor. It has projected the market could expand to $8 billion by 2016. Despite all the market upside, capturing these proteins is no small task, as a medium-sized whey protein concentrate plant can cost an estimated $30 million to get up and running.

Since 1970, U.S. cheese has gone from taking 19 percent of our milk supply to now accounting for between 42 and 44 percent. While cheese and whey remain intricately connected, whey is a relative newcomer to commercial markets and it has a boundless future as U.S. cheese plants outnumber whey plants 16 to 1. That is welcomed news because whey already contributes an estimated $1.80 per hundredweight to our milk checks. Given whey's potential, we are dedicating a four-part series on whey beginning on page 535 of the August 25, 2013 issue.

This editorial appears on page 542 of the August 25, 2013 issue of Hoard's Dairyman.