21726
The presence of several tentatively identified volatile flavour compounds ( VOCs ) , both during the enzymatic treatment and the lactic acid fermentation of the milk base , were monitored using a proton transfer reaction time - of - flight mass spectrometer ( PTR - ToF - MS ) .
 Chemical: lactic acid
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: lactic acid