Titratable acidity and pH changes of pasteurized milk by addition of Roselle flower extract in the refrigerator storage

Abstract

Pasteurized milk is milk that is heated below the boiling point in order to kill the pathogenic bacteria in the milk, but bacterial spores and certain bacteria have not been killed, resulting in the relatively short shelf life of pasteurized milk. One of the damages caused by bacteria is the increased acidity in pasteurized milk during storage. Roselle flower (Hibiscus sabdariffa LINN) extract is expected to be one of the natural preservatives in pasteurized milk. This study was aimed to determine the effect of increasing the level of Roselle flower extract and storage time on pH and total acid titrated pasteurized milk. The research design used was a completely randomized design factorial pattern 34 with three replications. A factor was the level of Roselle extract 0%, 2% and 4%, while B factor was storage time consist of 0, 3, 6 and 9 days which was repeated three times. The parameters measured in this study were the pH value and total titrated acid. Based on the results of the study showed that the addition of Roselle flower extract level and storage time significantly affected the pH value and total titrated acid. As the level of Roselle extracts increased, the pH value decreased and the total acidity of pasteurized milk titrated increased. Prolonged storage caused a lower pH and increased the total titrated acid. The study concluded that pasteurized milk with the addition of Roselle flower extract had implications for decreasing pH and a smaller increase in total titrated acid during storage compared to pasteurized milk without Roselle flower extract.