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The composition of the volatile fraction of yoghurts made from cows’, buffaloes’, ewes’ and goats’ milks was investigated during the 28 days of storage at 4 °C using solid‐phase microextraction technique (SPME) and gas chromatography coupled to mass spectrometry analysis (GC/MS). A total of 34 volatile compounds were identified in yoghurts during their storage at 4 °C, including aldehydes, ketones, alcohols, esters, acids, terpenes, hydrocarbons and sulphur compounds. In this study, acetaldehyde, diacetyl and acetoin, considered as the major compounds of yoghurt, were detected in all yoghurts.

The aim of the study was to determine whether thermosonication extends the shelf life of ayran, an acidic milk drink. The effect of thermosonication at different temperatures (60, 70 and 80 °C) and times (1, 3 and 5 min) on the physicochemical and microbiological characteristics, and sensorial properties of ayran during storage were investigated. According to the results, thermosonication applied at 60 °C decreased lower the bacteria counts, although the Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus counts decreased as the temperature and time increased. The yeast and mold levels in samples treated with thermosonication were <1 log CFU mL(-1) during storage period. The ayran samples had non-Newtonian behavior, and the consistency coefficients of the thermosonicated samples were significantly higher than that of the heat-treated samples. Regarding serum separation, the most effective thermosonication treatment was applied at 70 °C for 3 min. The sensory properties of the thermosonicated samples were better than the thermal-treated samples after storage.

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