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Guest Columns

Perspective:
Dairy Research

The changing face of whey

John Lucey

John Lucey, director of the Wisconsin Center for Dairy Research at the University of Wisconsin-Madison, contributes this column for Cheese Market News®.

Over the past few decades, whey has been transformed from an unwanted byproduct to one of the most desirable and value added dairy products in the industry. In fact, many large plants might say that they make cheese just to get the whey. This transition was not easy, however, as a great deal of research has gone into understanding all the properties of whey. While the nutritional benefits of whey and its co-products have become increasingly clear, often the greatest challenge for whey has been on the processing side. Permeate derived from the ultrafiltration (UF) of milk, cheese whey and (Greek yogurt) acid whey all have their own unique compositions and chemistry, which means processors have to be very selective when investing in a processing technology. Additionally, changes in the types of cultures used in cheese and the regulations surrounding each product also have created a number of challenges for whey processors.

Milk protein concentrate (MPC) and milk-derived UF permeate are two of the newer products being manufactured in the United States, so all the processing challenges are not as well known. Many cheese manufacturers who installed milk UF systems were already making whey protein concentrate (WPC) and thus producing whey permeate, so typically the two types of UF permeate are blended and then further processed through the plants’ existing equipment. One challenge that has occurred with the processing of milk permeate is that it has a considerably higher pH than any type of whey permeate. This difference in pH is enough to cause problems during processing of milk permeate including the precipitation of calcium, which fouls the RO filtration system and evaporator equipment. Research shows that either a slight reduction in pH or use of a calcium chelator (e.g., addition of citric acid) helps prevent problems due to calcium insolubility.

Sweet (cheese) whey is a very popular product that has unique processing challenges of its own. In particular, there has been a sharp increase in cheesemakers adding thermophilic cultures in their cheese make, specifically in commodity Cheddar, Gouda and cottage cheese. These thermophilic cultures help speed up the acid development and then reduce the likelihood of excessive acidification post-salting and cooling. Unfortunately, thermophilic cultures are unable to metabolize galactose, which builds up and causes drying and Maillard browning problems for the whey products containing the galactose. Not only are whey products containing galactose difficult to dry due to stickiness, the presence of galactose means there is less lactose which reduces lactose crystallization and the yield potential for manufacturing edible grade lactose.

Greek yogurt also is produced using thermophilic cultures that generate a lot of galactose. This acid whey contains more than twice the amount of galactose as the cheese whey made with thermophilic cultures, so its stickiness makes it nearly impossible to dry. The high levels of lactic acid in any acid whey also contribute to problems including browning and lower lactose yield. Recent research is finding ways to improve processing of Greek yogurt acid whey by removing some of the minerals/acid/galactose but there is still work to be done to make this newest type of acid whey economically feasible for more processors.

In the future, whey will continue to change. For example, soon, whey might not even come from a cheese plant as the technology currently exists to microfilter milk to produce a “whey” stream. This milk-derived whey has a very low fat content, has superior flavor, and does not have complications like added rennet, starter or annatto color compared to regular cheese whey. We’ve seen some remarkable innovations in this field, but they would not have been possible without the sustained research and collaboration between universities and the dairy industry. Maintaining this important relationship will be key to continued innovation and growth in the dairy industry.

CMN

The views expressed by CMN’s guest columnists are their own opinions and do not necessarily reflect those of Cheese Market News®.

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