In this study, the effect of Osmodehydrofrozen fruits on sensory, physical, chemical and microbiological properties of yoghurt and its quality during storage was evaluated. This research was done in two stages. At the first stage, the fruit percentage, type and addition time (before and after of fermentation) was determined, the results indicated that yoghurts which contained 10% apple or 13% strawberry and added after fermentation had better quality. Because of high osmotic activity of apple, the synersis value was lower in apple yoghurt. According to osmotic activity in both fruits, the synersis value was very lower than fruit yoghurts which contained untreated fruits. Taste value was higher in strawberry yoghurt and texture and mouth feel values was higher in the yoghurt with high percentages of fruit. The results of second stage (quality evaluation during storage) indicated that storage had significant effect on pH, acidity, synersis, taste and texture (p<0.05). The sample contained apple didnt have any mold and yeast; Coliforms disappeared after 7 days of storage. In samples which contained strawberry, yeasts were grown and coliforms disappeared after 7 days of storage.

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