Inhibition of Pseudomonas fluorescens by Hydroxycinnamic Acids and Their Alkyl Esters

Alkyl esters of six hydroxycinnamic acids and cinnamic acid were evaluated in a liquid medium for their effectiveness in inhibiting the growth of Pseudomonas fluorescens , a bacterium commonly implicated in food spoilage. Compounds were tested at concentrations of 0–250 ppm, using turbidity as a measurement of growth. At 125 ppm, esters of p‐coumaric and caffeic acids were more inhibitory than either methyl or propyl paraben. Methyl esters of methoxylated cinnamic acids were much less inhibitory than the methyl esters of the corresponding positional hydroxylated cinnamic acids. The results indicate that esters of certian of these naturally occurring hydroxycinnamic acids may be useful as food additives to extend shelf life by inhibiting microbial growth.