Effect of sterol biosynthesis-inhibiting (SBI) fungicides on the fermentation rate and quality of young ale beer

The influence of five sterol biosynthesis-inhibiting (SBI) fungicides (cyproconazole, diniconazole, epoxiconazole, flutriafol, and tebuconazole) on the fermentation and quality of young ale beer was assessed. Fungicides were individually supplied to the brewer wort to obtain a concentration of 0.2 μg/ml. A noticeable influence of the fungicide residues on the fermentation rate was observed in all cases. From the third day onwards, the fermentation rate was low in all treated samples. At the end of fermentation (8 days), statistically significant differences (p < 0.05) were found for the extract and attenuation values, which were higher for all the samples treated with fungicides. As a consequence, a higher amount of residual sugars (mainly maltose and maltotriose) was found in the beer. No significant differences were found for the pH and the polyphenol content after fermentation among the blank and the treated samples, while the values of colour intensity (lower) and tint (higher) in the beer were statistically different.