4404
1 - Octen - 3 - ol and ( 2E ) - hexenal had significant contribution to R . serra aroma .
 1 - Octen - 3 - ol, ( 2E ) - hexenal
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 1 - Octen - 3 - ol, ( 2E ) - hexenal