Syneresis provides an indication of the non-homogeneities in the gel system of the yogurt; thus, higher whey separation is related to gel instability which is also related to the pH of the yogurt system . Fig. 4 shows the syneresis of lentil flour and skim milk supplemented yogurt and control samples immediately after production and after 14 and 28 days of storage. On day 1, the 3% lentil flour showed the lowest syneresis, which was significantly lower (pb0.05) than for the 1–3% skim milk supplemented samples, whereas the 1–2% lentil flour supplemented samples had the highest amount of whey separation, which was significantly higher (pb0.05) than all the
other samples. After 14 days storage, the 3% lentil flour supplemented
yogurt still showed little syneresis. After 28 days, the 1–3% skim milk
supplemented yogurt samples had the maximum homogeneity followed by the 3% lentil flour, control sample,2% and 1% lentil flour supplemented samples. Yogurt supplementation with an increase in the total solid content, especially protein content,results in stronger texture and less whey separation This can explain the lowest syneresis in 3% lentil flour and 3% skim milk supplemented yogurt at day 7 (results not shown)and day 14.