They were then analyzed by capillary GC/MS as methyl ester acetates (prepared using acetic anhydride in acetic acid with perchloric acid catalyst) or as methyl ester trimethylsilyl derivatives (prepared using Tri-Sil, Pierce Chemicals, Rockford, IL).
The flavour compounds underlying the so-called 'yeast bouquet'; ethyl esters, acetate esters, fusel alcohols, carbonyls, and volatile fatty acids, are secondary metabolites synthesized by a wide range of microbial species.
All p-NP esters (acetate C2, butyrate C4, caprylate C8, decanoate C10, laurate C12, myristate C14, and palmitate C16) were respectively dissolved in anhydrous acetonitrile [ 23] at a concentration of 100 mM as substrates for analysis of substrate specificity.
(110) The most commonly used hydroxyl protecting groups are ethers (benzyl ethers), esters (acetates, benzoates), and acetals (benzylidene and isopropylidine acetals).
These included 31 esters (acetates and non-acetate esters), 8 sulphur-containing compounds, 10 alcohols, 8 aldehydes, 2 terpene derivatives and 2 other compounds.
Immature LSL and mLSL fruit were negatively correlated with both first and second axis because the concentrations of esters (acetates, diacetates and non-acetate esters) were low and, moreover, sulphur-containing esters were not detected.
The mature fruit of MSL exhibited the highest amount of esters (acetates, diacetates and non-acetate esters), and those melons were generally described by the assessors as having desirable fruity and sweet odours.
Esters (acetates and non-acetate esters) comprised more than 87% of the total volatiles collected from the iMSL fruit, a percentage which increased to more than 93% in the mMSL fruit.
Semi-volatile compounds included 9 esters (acetates and diacetates), 5 sulphur-containing compounds and a few other compounds (alcohols, aldehydes, furans, acids).
