Characteristics of PH changes, redox potential and fruit juice microflora for refrigeration storage

Juices and juicing products are rich sources of carbohydrates and trace elements, which makes them a favorable environment for the growth of microorganisms. This will cause microbial or enzyme spoilage, which reduces the shelf life of these products. In the production of fruit juices, the relationship between pH, acidity and redox potential is practical. Because low pH provides natural protection of the product from microorganisms. At a pH below 4.5, the development of many pathogens, such as Clostridium botulinum, becomes impossible. This reduces the amount of preservatives and ensure long -term storage of products. The purpose of the work was to determine the effect of the environment reaction (pH, redox potential), microbiots of fruit juices on their storage period and freshness. Determination of pH, redox potential of fruit juices was carried out by a pH-meter 150u, and microbiological parameters by standard techniques. Fresh fruit juices are found to have sour and slightly acidic pH (2.5–3.5) with a positive above 100 mv redox potential. The obtained values of these values should be taken as those that characterize their freshness. The pH of fresh fruit juices (grape, strawberry and orange) during five daily storage at + 4 °C does not undergo significant changes. During this period of time, the redox potential of these juices increased in the positive side, an average of 10 mV, and the lactic acid of the microbiota was not able to develop intensively. Under this storage mode, the number of yeast increased 3.0 and 3.4 times in grape and strawberry juices, respectively and on average 2 times in orange juice. Obviously, the pH and Redox potential change is associated with the development of microbiota in juices. Therefore, for a longer storage of fruit juices, it is necessary to maintain pH and redox potential at the initial level and stop the microbiological processes in them.