Ready-to-drink (RTD) beverages being marketed to the widest possible consumer base often incorporate some type of protein fortification. For this purpose, whey proteins are frequently an ingredient of choice. High-protein drinks, typically greater than 4% protein, generally are ingested for amino acid replenishment and anabolic muscle-building during and after exercise. Low-protein drinks are typically less than 4% protein and seem to be targeted to mothers of young children as a healthy alternative to carbonated soft drinks.

Whey proteins are very high in essential and branched chain amino acids which are necessary for serum replenishment during exercise and the anabolic period post-exercise. “These proteins are soluble at the pH of the digestive tract and increase blood amino acid levels in a much shorter period of time after ingestion, as compared to other protein sources which must be 'predigested' to first make them soluble,” states Dennis Vosen, technical director at Century Foods International. Also, some of the minor proteins present in ultra-filtered/micro-filtered (UF/MF) whey products have been shown to be important for digestive tract health and also display immunomodulatory characteristics.

Whey Manufacturing Technology

Both whey protein isolates (WPI) and whey protein concentrates (WPC) are used in beverages, their differences being mainly compositional. Material manufactured by ion exchange (IE) technology generally displays superior solution clarity and heat stability compared to that manufactured by filtration. However, there are WPIs made by UF/MF technologies that are clear in solution when rehydrated and incorporated into RTD beverages. According to Vosen, clarity is important because a consumer buying a chocolate RTD beverage might expect it to have a thin, opaque, milk-like appearance and mouthfeel; however, that same appearance and mouthfeel is less likely to be acceptable in a tropical punch product, where fruity and light might be the expectation.

Heat treatment and pH are critical for shelflife, but pH also impacts flavor. For reference, the pH of orange and lime juice is 3.5 and 2.3, respectively, with the main acidulant in these products being citric acid. On that note, research by Century Foods International has shown utilization of organic acidulants leads to protein instability in beverages with moderate to high amounts of protein. In these types of products, it is necessary to use inorganic acidulants, but these can impart undesirable flavor notes that need to be masked.

Beverage Shelflife

High-acid beverages (pH <4.4 and often <3.5) encounter very few microbial species that will grow. In addition, these products are generally pasteurized at >185°F and filled at approximately 182°F. The fill temperature—along with bottle inversion post-capping—essentially sterilizes the interior of the container and the cap. The resulting shelflife of these products is one year, but could effectively be longer than that. All whey sources being equal, and with adequate quality control of the ingredients, the choice of whey source has no bearing on shelflife.

For more information:
Century Foods International, Sparta, Wis.
Dennis Vosen • 608-269-1900 •