Biomedical Engineering Reference
In-Depth Information
Fig. 11.1
Process chart for
boza preparation
as raw materials. The end product is a fairly thick liquid with pale yellow appearance,
and a mixed sweet and sour taste that is characteristic for boza. Starter cultures for
boza production may originate from a previous boza fermentation, sourdough, pure
cultures, or yoghurt. Arici and Daglioglu [
1
] review the characteristics of boza and
its history more in detail. Turkey and Bulgaria are the heartlands of boza.
The process of boza fermentation is illustrated in Fig.
11.1
(based on [
1
] ).
Cooking of pre-processed (cleaned, milled) cereal raw materials into a slurry is fol-
lowed by a cooling and straining stage, sucrose addition (up to 20% w/w), inocula-
tion with a starter culture, overnight fermentation, and finally cooling and packaging
(Fig.
11.1
). Water is added during processing in order to adjust the consistency of
the slurry. The fermented boza exhibits pseudoplastic rheological behaviour, i.e. its
apparent viscosity decreases with increased shear rate [
2,
3
] .
Hancioğlu and Karapinar [
4
] were among the first to monitor boza fermenta-
tions. During a 24 h fermentation, acidification took place, the pH dropped from 6.1
to 3.5, and final cell counts of lactic acid bacteria and yeasts were 5 × 10
8
and 8 × 10
6
,
respectively. Gotcheva et al. [
5
] observed that glucose accumulated and free amino
nitrogen levels decreased during boza fermentation, of which the latter observation
