Development of a shelf-stable dairy protein beverage

The purpose of this project was to create a shelf-stable high protein beverage using whole milk and milk protein isolate (MPI) with added coffee flavor and non-caloric, natural high-intensity sweeteners. This product fills a gap in the market and improves upon the quality of current dairy protein beverages. Potassium citrate was also added to reduce sedimentation by preventing protein coagulation during heat sterilization. Effect of different levels of citrate were measured in beverages of different protein contents and pH levels. Citrate was added to beverages in levels between 0-0.75% by weight. Protein levels were adjusted to 8% (equivalent to 28g protein/12oz serving), 9%, and 10%. pH was adjusted to 6.8 or 7.0. Beverages were filled into size 300x407 (15oz) cans and sterilized in a still retort at 250°F for 20 minutes. Particle size analysis was performed as an indicator of degree of protein coagulation. At 0.25% citrate, particle size decreased 13-25% for the protein levels tested. Above 0.25%, particle size increased. On average, particle size was smaller in beverages at pH 6.8 than pH 7.0. Sensory analysis was performed on chilled samples containing 8% protein using a panel of 80 adults, primarily males age 21-34. Three samples with different sweetener profiles were tested; a combination of stevia and monkfruit was preferred based on overall liking score of 5.9 on a 9-point scale. Added citrate did not diminish creaminess or mouthfeel liking, which scored 6.0. Although sweetness was acceptable at 5.5, data shows that a higher level of sweetness would be preferred. Coffee flavor was liked by panelists with a score of 6.0. These findings show that this beverage containing 28g protein/serving, coffee flavor, and natural sweetener is liked by target consumers and with minor adjustments to sweetness is ready for commercialization. INTRODUCTION In the last ten years, there has been a significant increase in consumer interest for high protein products. More and more products each year are being released that tout the “high-protein” label (Archibald, 2004), and consumers are responding favorably to them. With the recent trends in health and wellness, those looking to consume nutrient-dense foods while increasing satiety and building muscle have found protein-fortified snacks and beverages (Mintel, 2013). A number of different protein sources are employed in these protein-rich foods including soy, whey, rice, pea, and casein (Fishel, 2012). In beverages with milk proteins specifically, milk proteins are generally added to water-based formulations to create shelf-stable products, while those made with milk are refrigerated (Ensure, Muscle Milk). Furthermore, these products that use milk protein often contribute fat with canola, soy, corn, or other oils rather than milk fat, which has recently been linked to certain health benefits (Juarez et al, 2015). With liquid milk prices increasing and consumption decreasing, dairy producers need new ways of attracting consumers to milk beverages. Considering their rising popularity, protein beverages are an obvious way to do so. However, in order to compete with other shelf-stable products, the milk-based beverages should be UHT (ultra-high temperature) processed and aseptically packaged, rather than ultrapasteurized or pasteurized and refrigerated. This commercial sterilization will prolong shelf life and erase the need for refrigeration in shipping and storage (Walstra, 2006).