Effect of protein concentration on the properties and structure of concentrated yogurts

Abstract

Reading RG6 6AP, UK Concentrated yogurts were produced by traditional (control), direct reconstitution, ultrajiltration and reverse osmosis techniques. The membrane techniques were applied either before or soon after incubation. The physical properties of the samples were monitored using a penetrometer (set yogurt) and viscometer (stirred yogurt), and the results indicated that different manufacturing techniques led to differences in the rheology of the concentrated yogurts. As expected, samples with high protein contents had greater gel strengths. Also, the concentration techniques caused large differences between the samples, even at the same protein level. The rheological properties correlated well with the microstructure as monitored by confocal laser scanning microscopy. In general, larger compartments in the network were associated with a weaker structure.

Rheological properties of stirred yoghurt as affected by gel pH on stirring, storage temperature and pH changes after stirring

“…The rheological properties of set-style, that of stirred gels and the whey retention capacity were correlated with each other in agreement with the literature (Cayot et al, 2003;Lee and Lucey, 2006;Lucey et al, 1997aLucey et al, , 1998aOzer et al, 1999). They all appeared to be greatly influenced by the pH value on stirring.…”

“…The factors responsible for the increase in viscosity of stirred yoghurts are therefore essentially the same as those that increase the firmness of set-style yoghurts. A few recent studies have shown direct correlations between rheological properties or spatial properties of set-style and stirred yoghurts (Cayot et al, 2003;Lee and Lucey, 2006;Ozer et al, 1999;Van Marle, 1998;Van Marle and Zoon, 1995). However, as far as we know, the effect of the structural properties of set-style gels on the structure recovery of stirred yoghurt has not been yet investigated.…”

Manufacturing, properties and shelf life of labneh: a review

“…(1989) that UF offers an excellent alternative to the cloth bag method for labneh making. Moreover, it has been indicated by Ozer et al . (1999a,b) that different manufacturing techniques led to differences in the rheology of concentrated yogurts and that rheological behaviour of labneh depended on the protein concentration and the severity of mechanical agitation during membrane treatment.…”

Minimising generation of acid whey during Greek yoghurt manufacturing

“…This may be due to the incorporation of MPC and the draining of whey enhancing the casein concentration and ultimately strength of casein network due to greater non-covalent interactions. Furthermore, the cloth bag draining has apparently allowed enough time for establishment of a strong gel matrix (Ozer et al 1999). Removal of whey is far more important than the casein content to achieve the required viscoelastic behaviour (Bong & Moraru, 2014).…”