Influence of pasteurization and storage conditions on microbiological quality and aroma profiles of shalgam

Abstract

Shalgam is a traditional Turkish fermented beverage produced by the lactic acid fermentation of black carrot, salt, sourdough, bulgur flour and drinkable water. Aroma and microbial profiles of shalgams were examined based on the effect of pasteurization and storage parameters. At the beginning of the storage, the pH of the samples was 3.89, the acidity was 6.06–6.66 g/L and the brix values ranged from 2.67 to 2.73, at the end of storage these values were 3.89–3.98 for pH, 5.94–6.49 g/L for total acidity and 3.07–3.27% for brix. Total aerobic mesophilic bacteria decreased in unpasteurized sample, although the number of lactic acid bacteria increased and yeast and molds stored at 4 °C increased with storage time. A total amount of 32 and 35 volatiles were identified and amount of these compounds decreased during storage for unpasteurized and pasteurized samples, respectively. The total amount of volatiles, which was 1558.63–2179.49 μg/L at the beginning of storage, decreased to 556.70–800.12 μg/L at the end of storage. Samples were separated successfully according to storage times in terms of aroma profiles by principal component analysis (PCA). While the samples of shalgam stored for 0 and 7 days were characterized by most of the volatile compounds, samples stored for 14 and 30 days were characterized by ethyl alcohol, 4-phenyl-3-buten-2-one and myristicin. When effect of pasteurization process and storage parameters were evaluated comparatively, storage time and temperature were found more effective on shalgam quality.