Determination of Some Quality and Safety Parameters for Black Raisin Juice

Abstract

The aim of the present study was to determine the safety and the quality parameters of raisin juice, such as total soluble solids (TSS), pH, titratable acidity (TTA), kinds and quantity of sugars, phenolic acid compounds, polyphenoloxidase (PPO) enzyme activity, water activity and total microbial counts. The total soluble solids and pH values were significantly decreased after two weeks of storage, while the titratable acidity in most samples were slightly changed. Glucose, fructose and sucrose as well as three kinds of phenolic acids such as gallic, chlorogenic and vanilic acids were determined in all samples. Total microbial contents of the freshly prepared raisin juice and of the raisin juice stored for one and two weeks did not significantly changed. The water activity was slightly decreased, while the polyphenoloxidase activity was significantly decreased, after storage for two weeks. Consequently, it can be said that the freshly prepared raisin juice and the raisin juice stored for one week have superior sensorial properties than the raisin juice stored for two weeks.