RHEOLOGICAL PROPERTIES OF CONCENTRATED YOGURT (LABNEH)

The effect of six techniques for the elevation of the total solids on the rheological properties of labneh were investigated using controlle d-stress dynamic rheometer. All samples exhibited a weak viscoelastic gel structure with the storage modulus (G') higher than the loss modul us (G '') over all of the measured range. None of the experimental mat erials produced the same overall gel strength as the control made by d raining with traditional cloth-bags. The changes in the storage modulu s (G') as a function of amplitude sweep were mirrored by changes in th e loss modulus (G ''). Considerable differences in the loss tangent (G ''/G') values of the various materials were observed at higher stress amplitudes. Rheological differences in the overall gel strength at lo w amplitude and frequency suggest that, although the type of protein i nteractions in each case may be similar, there are differences in the degree of interactions. Subsequent breakdown at higher amplitudes and frequencies suggests that the overall domains of the treated proteins may have been reduced, and that different methods of manufacture may b e producing materials that have different space occupancy in the gel.