Evaluation of quality properties and shelf life of functional colored yoghurt incorporating containing beetroot, spinach and tomato extract

The purpose of this study was production of functional colored yoghurt using plant components for increasing the dairy product variety and improvement of their quality, nutritional properties and shelf life. In this study, 2, 4 and 6% of extract concentration were evaluated for producing the functional colored yoghurt based on sensory properties by panelists. The concentration of 4% (Brix 70) was selected for producing yoghurt samples using beetroot, spinach and tomato extracts. Then, colored yoghurts were evaluated on physicochemical, phenolic compounds, microbiological and texture properties every 7 days during 21 days storage. The results showed that spinach and control yoghurts had higher protein and fat content, respectively. pH, S. thermophiles and L. bulgaricus count decreased whereas acidity, syneresis mold and yeast count increased during storage period. In all yoghurt samples were not detected S. aureus and E. coli bacteria and coliform count was less than 10 CFU/gr which reflects the safety of the manufacturing process. Finally, results revealed that beetroot yoghurt not only had high sensory and nutritional quality (phenolic compounds) and acceptable texture (high viscosity) but also showed microbiological quality and high shelf life.