The aroma of the probiotic yogurts with and without supplements

Svrha ovog rada je istražiti promjene do kojih dolazi tijekom čuvanja nekih probiotičkih mliječnih proizvoda, a ovisno o trajanju i temperaturi skladištenja. U radu je ispitivan udjel komponenata arome uzoraka probiotičkih jogurta tijekom skladištenja na + 4 °C i + 20 °C. Određivani su acetaldehid, diacetil, etanol te mliječna, limunska i octena kiselina, a analize su vršene počevši od 0-tog dana svaki peti dan tijekom 20 dana. Acetaldehid, etanol, te mliječna, limunska i octena kiselina određeni su enzimskim metodama, a diacetil kolorimetrijski. Rezultati pokazuju da se udjel acetaldehida smanjuje tijekom skladištenja pri čemu je pad koncentracije brži na +20 °C. S druge strane, koncentracije diacetila, etanola i octene kiseline rastu tijekom skladištenja na obje temperaturne razine. Koncentracija mliječne kiseline tijekom skladištenja raste na obje temperature, te nakon 20 dana skladištenja poraste dvostruko. Isto tako se i koncentracija limunske kiseline udvostručuje tijekom skladištenja. Porast svih određivanih organskih kiselina nešto je veći na višoj temperaturi skladištenja. 003.The purpose of this study was to establish the changes in aroma compounds of fermented milks with probiotics during storage as a function of time and temperature. The aroma compounds concentration in probiotic yogurt samples, during storage at + 4 and +20°C were studied. Acetaldehyde, diacetyl, ethanol and organic acids (lactate, acetate, citrate) content were determined during 20 days, every fifth day from the beginning of storage. Acetaldehyde, ethanol, lactic, citric and acetic acid concentration were determined using an enzymatic method, while diacetyl concentration was determined using colorimetric method. The results showed that the acetaldehyde decreased during storage. The decrease was higher at elevated temperature. On the other hand, diacetyl, ethanol and acetic acid increased during storage at both temperatures. The concentration of lactic acid increased during storage at both temperature and at the end of storage it was doubled. The amount of citric acid increased in the same manner. The increase of all organic acids during storage was higher at elevated temperature