In a broader context, fruit juice constitutes a colloidal mixture of soluble and suspended solids, including low molecular-weight solutes like sugars, organic acids, pigments, and vitamins. Additionally, it encompasses high-molecular-weight solutes such as proteins, enzymes, and pectic substances.
The initial pasteurization takes place either after juice extraction or as the first step in the evaporator, typically at temperatures ranging from 95 to 98°C for a duration of 10 to 30 seconds. This step aims to extend shelf life by deactivating specific enzymes and microorganisms like yeasts, molds, and bacteria.
The subsequent pasteurization occurs before the juice is filled into its container, with a focus on eradicating microorganisms that could contaminate the fruit juice during bulk storage or in juice reconstituted from concentrate. This second pasteurization, typically carried out at a pH below 4.2, involves a temperature of 95°C and a holding time of 15 seconds.
Upon completion of the pasteurization process, there is a noted 7% increase in viscosity and a 22% decrease in cloudiness after 21 days of shelf life. The primary goal of pasteurization is to mitigate these undesirable reactions, and in certain instances, it can even enhance the inherent quality of the initial fruit.
Juice Pasteurization for Stability
