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The formation of the major flavour compounds ( acetaldehyde , diacetyl , acetoin , and 2 - butanone ) followed a sigmoidal trend described by the modified Gompertz model .
 Chemical: acetaldehyde; Chemical: diacetyl; Chemical: acetoin; Chemical: 2 - butanone
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: acetaldehyde; Chemical: diacetyl; Chemical: acetoin; Chemical: 2 - butanone