Sharon Gerdes
Sharon Gerdes is a certified food scientist and author who writes extensively about dairy’s role in health and wellness. Learn more at

The world was stunned when 42-year-old Princess Kate announced that she was being treated for cancer after abdominal surgery that required a two-week hospital stay. The World Health Organization estimates that there were 20 million new cancer cases worldwide in 2022. 

In the United States alone, 4 million people have some type of abdominal surgery, which may require a liquid diet for a period of time. Nestle Health Sciences reported that an estimated 25% of older adults are malnourished or at risk of malnutrition, with an expected increase as the population ages. 

Ready-to-drink (RTD) protein shakes support muscle growth and weight management, and can also be a lifeline for individuals experiencing cancer, abdominal surgery, or frailty due to aging. RTD shakescome in a wide range of protein levels, flavors, clarity and fortification.

The term Oral Nutrition Supplements (ONS) is used to describe energy- and nutrient-dense feeds designed to increase nutritional intake in individuals who are experiencing disease related malnutrition. The majority of ONS supplements are based on cow’s milk protein. 

Max protein RTDs

A wide range of RTD protein drinks and ONS are available in grocery and pharmacy stores, with additional specialized products available online or through medical sources. Currently, 30 grams is a typical level for “max protein” drinks delivered in an 11-ounce serving.

One example is Boost Glucose Control Max 30 g Protein Balanced Nutritional Drink. This drink, designed to produce a lower blood sugar response, is formulated with milk protein concentrate and milk protein isolate. 

Ensure Max Protein Café Mocha Nutrition Shake contains 30 grams of protein, plus 25 essential vitamins and minerals and 4 grams fiber blend. Fiber intake can be challenging on a liquid diet. 

The Fairlife Nutrition Plan High Protein Chocolate Shake provides 30 grams of high quality protein from filtered lowfat Grade A milk. The addition of the lactase enzyme allows this product to make a “lactose-free” claim on the label. 

Topping the max protein gamut, GNC’s Wheybolic contains 40 grams of protein from milk protein concentrate and whey protein isolate in a 14-ounce serving. 

Formulation strategies

Sometimes consumers prefer a tart, fruity drink. In these applications, a whey protein ingredient provides clarity in low pH applications. There are customized dairy protein ingredients available commercially for both high- and low-acid RTD beverages. 

“In the high-acid category, the ‘clear whey protein isolates’ are already pH adjusted to 3.0-3.4 so they are easily incorporated in a formulation without the need for additional acids. These ingredients will provide good heat stability and high clarity to a protein water or protein juice application,” says KJ Burrington, vice president of technical development, American Dairy Products Institute, who also authors “Culturally Speaking” articles for Dairy Foods.

“Agropur Ingredients has whey protein isolates, hydrolyzed proteins, and purified protein factions that can be used in a variety of high protein beverages, allowing the formulator to get either a low pH or a neutral pH beverage, while avoiding off-flavors associated with protein fortification,” said Peggy Ponce, director of Product Innovation Ingredients, Agropur, Eden Prairie, Minn. “In low pH beverages, we can deliver with ease 20 to 25 g. protein per 500 ml. serving. With additional effort in formulation, we can deliver up to 45 to 50 g. per 500 ml. serving. Functional whey proteins, such as hydrolyzed whey proteins, can be incorporated into neutral beverage formulas to deliver up to 20 to 25 g. protein per 330 ml. serving.” 

“A careful adjustment of pH levels and processing conditions during formulation and production can improve protein solubility and stability,” she continues. “Product palatability and consumer acceptability can be improved by using complementary flavors and appropriate sweeteners. Flavors such as citrus and some floral notes go well with low pH beverages. Sweet and intense flavors imply permissible decadence and nutrition. These flavors are better suited for neutral pH beverages.” 

Burrigton suggests processor make sure that the dairy protein ingredient is reconstituted sufficiently to maximize its heat stability and overall performance. “Micellar casein is an ingredient that has good solubility and heat stability and very low levels of whey protein, which results in lower sulfur aromas and flavors in a low acid, UHT (Ultra High Temperature) beverage than a typical milk protein concentrate or isolate,” Burrington explains. 

“There are also modified milk protein isolates that have reduced calcium content which allow formulators to reduce and or even eliminate the need for buffers and calcium chelators,” she notes. “With no buffers or calcium chelators listed as ingredients, the reduced calcium milk protein ingredients provide a cleaner label.” 

ADPI members and end users of dairy ingredients can access technical support for beverages and other applications by contacting Burrington. Another great resource for end users is its dairy ingredient supplier.