The Effect of Ultra High Temperature (UHT) Processing towards pH and Total Soluble Solids Stability of Reconstituted Orange Juice, Jasmine Tea, and Vanilla Milk during Refrigerated, Ambient, and Incubated Storage.

Abstract

Ultra High Temperature treatment is a process of heating the product between 135 and 145 C for around 1-10 seconds which resulted in an effectively sterile product with a shelf life that lasted months at ambient temperature. The UHT system used in PT XYZ is an indirect small-scale process plant initially and mainly used for clients to conduct trials for their products and application to test whether there are sensory changes after heat treatment. To fully utilize the machine and ensure its capability in maintaining product safety, a stability test focusing on the pH, brix content, and sensory changes in various temperatures is conducted. The experiment utilized three different types of beverages which were reconstituted orange juice, jasmine tea, and vanilla milk in which these beverages were stored in three different storage temperatures (4oC, 25C,40C) for four weeks and observations were made in each week. pH of orange juice remained stable, while the brix value generally decreased overtime and at higher storage temperatures. Jasmine tea was observed to have a decrease and fluctuation in the pH measurements and stable brix value. Whereas both pH and brix of vanilla milk were observed to have an extreme fluctuation and instability as well as major physical changes. All the samples showed a flavor impartment throughout the storage duration especially in higher temperatures. These changes and instability were affected by the chemical changes induced by heat treatment, microbial spoilage, and storage temperature that affect the properties of the beverages