Penetrometer values of all samples were given in Fig.1. Higher penetrometer values indicated higher firmness. TGase treatment resulted in an increase in gel strength of labneh samples. In terms of penetrometer values, statistically significant difference were found between the samples (P < 0.01). Significant increases (P < 0.05) in penetrometer values were observed only in the samples with TGase at levels of 2 and 4 U/g protein. When statistically grouped C, 0.5 U, and 1 U took place in the same group, while the 2 U and 4 U in the other group. Pretreatment of the milk with TGase at the level of 2–4 U/g protein has increased the firmness of the labneh samples more than
14–15 times compared to the untreated sample. On the other hand, there were no correlation between the pen- etrometer values and the total solid content or the ratio of fat to non-fat solids.