Impacts of depectinization of pear juice on alcoholic fermentation and indole formation.

Background: Recently, a producer of fermented ciders observed 'vinyl' off-odors formed during fermentation of pear juice previously depectinized at ≥ 49 °C but not if depectinized at lower temperatures. The objective of this study was to investigate the source of this spoilage and evaluate factors that affect formation.

Results: Analysis of untainted and tainted samples obtained from the producer determined the causative agent to be indole, a compound sometimes produced by yeast (Saccharomyces cerevisiae) during fermentation.