Physico-chemical and rheological properties of Lebanese kishk powder, a dried fermented milk-cereal mixture

Kishk is a traditional fermented milk-cereal mixture, widely consumed in Lebanon. Twenty Lebanese kishk powder samples were collected from artisanal producers in four Lebanese regions, in order to assess the effect of milk base and cereals on their physicochemical properties, functional and rheological properties. Milk type affected the fat content and color parameters of kishk samples. Multi-scale exploration of kishk microstructure revealed a complex network of macroconstituents (milk protein and wheat starch) embedded in a thick layer of fat. The mechanism of kishk rehydration was then exploited by analyzing the water sorption isotherms and observing the morphometric changes in the particles of this powder subjected to different relative humidities. From powder rheology measurements, kishk showed an intermediate flowability behavior and cohesiveness, associated to its high fat content as a binder between the particles.