Volatile Constituents of Grass and Corn Silage. I. Steam Distillates

Abstract

Extracts of distillates from grass and corn silages contained the normal C2 - C6, isobutyric, [alpha]- and [beta]-methylbutyric acids and the corresponding aldehydes. Acetone, butanone, benzaldehyde, phenylacetaldehyde and furfural were detected in both types of silage while traces of 3-(methylthio) propanol were found only in the grass silage. The acid- and carbonyl-free neutral fractions possessed odors characteristic of the respective silages. The major portions of these fractions distilled over a range of 35-100 C and contained the normal C2 - C5, secondary C3 - C5, and the iso-C4 and C5 alcohols. Hexanol, 2-hexanol, and cie-3-hexanol were detected in the high boiling residues from the grass silage neutrals. Although several ethyl and propyl esters were identified in the neutral fractions from both silages, it was found that some of these could have been formed during the extraction of the distillates. The volatile constituents of silages responsible for their characteristic aromas and which could possibly be responsible for feed flavor in milk from silage-fed cows are concluded to be complex mixtures of alcohols, carbonyis, and probably esters of the alcohols and volatile acids present in silages.