Microbiological Quality and Sensory Properties of Tarhanas Produced by Addition Saccharomyces cerevisiae and Sourdough as Starter Culture after Different Fermentation Periods

Aims: The aim of this study was to investigate some effects of different starter cultures
(Saccharomyces cerevisiae and sourdough) and different fermentation times (7, 14 and 21 days) on
tarhana.
Place and Duration of Study: Food Engineering Department, Namık Kemal University, Tekirdag,
Turkey, October 2017.
Methodology: Wheat flour, full-fat commercial set-type yoghurt made from cow milk, starter culture
(sourdough and dried baker’s yeast as Saccharomyces cerevisiae), fresh red pepper, onion, tomato,
dill, parsley, dry mint, table salt and ground black pepper were used as materials. Tarhana doughs
prepared using these materials were fermented for 7, 14 and 21 days. Physicochemical and
microbiological analyses of tarhana samples were performed using standard methods. Tarhana soups
were evaluated by panelists in terms of sensory properties at the end of the 21st day.
Results: pH values of baker's yeast added samples were lower than the others and their acidity were
higher than the others during the fermentation period. Dry matter of samples increased with the
prolongation of fermentation time. The dry matter of the sample produced using baker's yeast was
slightly higher than that of the other sample at day 21. Total mesophilic aerobic bacteria and lactic
acid bacteria (mesophilic rod) counts of tarhana samples with sourdough were always higher than the
others during the fermentation. Yeast-mould counts of tarhana samples with baker’s yeast decreased
slightly during the fermentation period, but were higher than the others. The coliform group bacteria
was not detected on the 7th day of fermentation. Samples were left to fermentation for 7 and 14 days
were less favoured than those were left to fermentation for 21 days. On the 21st day of fermentation,
the sample added dry baker’s yeast was the most favoured sample.
Conclusion: As a result of the sensory analysis, considering the total score, although the difference
between them is slight, baker's yeast added tarhana soups were more favoured than the others. Also,
with the prolongation of the fermentation period, in terms of sensory properties, tarhanas were more
favoured and microbiologically safer tarhanas were obtained.