Stability of Aseptic Flavored Milk Beverages

Abstract

The dairy industry has promoted milk as nature’s near perfect drink as well as an important beverage for U.S. consumers. Milk is high in calcium and therefore, a major source of dietary calcium, especially for persons of Caucasian origin. However, during the last half century, the per capita consumption of milk as a beverage has been consistently decreasing, whereas the consumption of soft drinks and other novel beverages has been steadily increasing. There are many reasons for these changes in beverage consumption patterns. For example, many consumers consider milk high in calories, fat and cholesterol. Other consumers are lactose intolerant and thus avoid milk and milk products. Perhaps the primary explanation for the decline in milk consumption is that most U.S. consumers, especially the younger generation, do not consider milk as refreshing. They find milk bland in taste, with an objectionable mouth coating after taste. Many adolescents simply consider milk as an old-fashioned beverage (Sloan, 1995; Harnack et al., 1999). The dairy industry has sold pasteurized flavored milks such as chocolate and strawberry for a long time. Mixtures of fruit juices and milk have also been developed (Shenkenberg et al., 1971; Luck and Rudd, 1972) since consumers consider both fruit juices and milk very healthy foods. Research development of other novel dairy beverages has recently been discussed (Kadan and Champagne, 1997). Pasteurized milk beverages require refrigeration and therefore, have very limited shelf life at room temperature. Soft drinks, on the other hand, are stable at room temperature and enjoy the advantage and convenience of storage under such conditions. Aseptic processing allows milk beverages to be stored at room temperature with long shelf life. In the U.S., the Food and Drug Administration (FDA) requires the precise temperature/time conditions for aseptic processing of dairy beverages and process (Dunkley and process (sterilized in the container)). Continuous flow sterilization is achieved in heat exchangers, followed by immediate cooling and aseptic packaging. Sterilization temperatures range from 130–150°C with a holding period of 2–5 s for continuous sterilization ((referred to as ultra-high-temperature UHT) or high temperature short time (HTST)). With the case of in-container sterilization (retort), the beverage is filled in the metal or glass containers and then autoclaved at 117–120°C for 10–20 min. The pasteurization or ultra-pasteurization requirements are controlled by specific standards for time/temperature requirements by the Pasteurized Milk Ordinance (FDA, 1999).