Effect of increasing zearalenone levels on the coagulation properties of milk and the viability of yogurt bacteria

Abstract

The effect of increasing levels of zearalenone (ZEA) artificially supplemented to milk on the coagulation characteristics and the viability of Lactobacillus bulgaricus and Streptococcus thermophilus was examinated. Cow milk was inoculated with the yogurt culture YC-180 – YO-Flex and divided into 72, 25-ml flasks. Two samples were collected before fermentation (0 h) and remaining 70 flasks were divided into 7 groups – control (C), Z0 with 0.5 ml of ethanol and Z10, Z100, Z250, Z500, and Z1000 that were spiked with ZEA to reach the final ZEA concentrations of 10, 100, 250, 500, and 1000 µg/l, respectively. Samples were fermented at 43 ± 2°C for 5 hours. Two samples per group were collected at 1-h intervals and analysed on pH, titratable acidity, ZEA and count of Lb. bulgaricus and Str. thermophilus. The addition of ZEA resulted in slower acidification in Z100, Z250, Z500, and Z1000. The highest ZEA binding capacity (25%) was observed in Z10 and the lowest (3.1%) was found in Z1000.