Fermentation, drying and different tarhana ingredients
affect the functional properties of tarhana [Bilgiçli
2009, Çelik et al. 2005, Hayta et al. 2002]. Functional
properties of tarhana samples are summarised in Table
2. Proteins in the dispersion resulted in lowering
of the surface tension at the water-air interface, thus
creating FC. Since FS is governed by the ability of
the fi lm formed around the entrapped air bubbles to
remain intact without draining, it follows that stable
foams can only be formed by the highly surface active
solutes [Kaushal et al. 2012]. From this study resulted
that addition of a higher proportion of yoghurt
(sample T3) signifi cantly reduced FC, whereas FS
was increased. Tarhana contains milk proteins, mainly
casein, and wheat proteins (for example glutenin and
gliadins) originating from yoghurt and fl our used in
tarhana preparation [Hayta et al. 2002]. Some food
proteins are capable of forming good foams, and their
capacity to form and keep stable foams depends on
the type of protein, degree of denaturation, pH, temperature
and processing methods [Hayta et al. 2002,
Çelik et al. 2005]. Differences in FC and FS among
the samples may refl ect structural changes of proteins
in tarhana during fermentation and drying [Çelik et
al. 2005]. The decrease in FC of sample T3 can be
explained by the proteolytic activity of present microorganisms,
which lead to the weakness in the gas
absorption property of proteins present in the tarhana
formula [Çelik et al. 2005].