Showing 2 results for Yoghurt
M Sh.zeinodin, M Tadyoni, Sh Dokhani, S Soleymanian Zad,
Volume 13, Issue 48 (7-2009)
Abstract
Exo-polysaccharide (EPS) production by some lactic acid bacteria (starter) during fermentation could affect the physical properties of yoghurt. In this study, at first EPS content and its effects on physical properties of three traditional (S1, S2 and G) and one industrial (I) yoghurt samples were studied. The results showed that there was significant differences in fat content, solid non-fat content, pH, EPS content, viscosity, elasticity and sensitivity to syneresis among samples. Statistical analysis based on a completely randomized design revealed that a significant correlation exists between EPS content and viscosity as well as resistance to syneresis of the samples. Fat content and solid non-fat content of the samples showed no correlation with physical properties of the samples. In the second phase of the study, to remove effects of raw milk composition and to be able to attribute the results to the EPS producing activity of the starter, skim milk was used to produce yoghurt samples using yoghurt samples tested in the first stage only as sources of starter. In these yoghurt samples, there were significant differences between amount of EPS and physical properties of yoghurts. There was also a significant correlation between EPS content and physical properties of each sample.
N Vahedi, M Mazaheri Tehrani, F Shahidi,
Volume 13, Issue 48 (7-2009)
Abstract
In this study, the effect of “Osmodehydrofrozen” fruit addition on sensory, physical, chemical and microbiological properties of concentrated yoghurt and its quality during storage was evaluated. This research was done in two stages. At the first stage, fruit percentage, type and addition time (before and after fermentation) was determined. The results indicated yoghurts containing 10% apple or 13% strawberry, which was added before fermentation had a better quality. Because of high osmotic activity of apple, the synersis was lower in apple yoghurt in comparison with strawberry yoghurt. According to osmotic activity of both fruits, the synersis value was much lower than that of fruit yoghurts, which contained untreated fruits. Taste value was higher in strawberry yoghurt and texture and mouth feel values were higher at low percentages of fruit. The results of the second stage (quality evaluation during storage) indicated that storage had a significant effect on pH, acidity, synersis, taste and texture (P<0.05). In samples which contained apple, coli forms disappeared after 7 days of storage. In samples that contained strawberry, coli forms disappeared after 7 days of storage.
