Metabolism of Natural Volatile Compounds by Strawberry Fruit

As part of experiments to evaluate naturally occurring volatile compounds as fumigants to reduce microbial populations, especially pathogenic fungi on strawberry fruit, several test compounds were found to be metabolized by the fruit to yield additional volatile compounds. The natural products used as fumigants comprised alcohols, aldehydes, ketones, esters, and hydrocarbons and were tested with fruit in closed containers at refrigeration (2-4 °C) temperatures. The three principal types of volatile metabolites formed by strawberry fruit as determined by GC and GC-MS analyses of headspace vapor samples were esters produced from aliphatic alcohols [e.g., (Z)-3-hexenyl acetate from (Z)-S-hexen-1-ol], alcohols formed by the reduction of aliphatic aldehydes (e.g., 1-hexanol from hexanal), and saturated products from reduction of carbon-carbon double bonds conjugated with an aldehyde or ketone carbonyl moiety [e.g., 2-nonanone from (E)-3-nonen-2-one]. Metabolic pathways leading to the formation of the volatile products and applications for the metabolites are discussed.