Inhibition of Clostridium botulinum by Spice Extracts and Aliphatic Alcohols.

Alcoholic extracts of spices were prepared and tested for inhibition of Clostridium botulinum in culture media. Mace (the outer covering of the seed of Myristica fragrans ) and achiote (annato, Bixa orellana ) were the most inhibitory of 33 spices studied. Also quite active were bay leaf ( Laurus nobilis ), white and black pepper ( Piper nigrum ) and nutmeg (the seed of M. fragrans ). Less active were rosemary ( Rosmarinus officinalis ), clove ( Eugenia caryophyllata ), oregano ( Oreganum vulgare ), turmeric ( Circuma longa ), thyme ( Thymus vulgaris ), and paprika ( Capsicum annuum ). Of the series C₁ to C₁₈, aliphatic straight chain alcohols of C₁₄ or C₁₆ chain-lengths were the most inhibitory against C. botulinum with a minimum inhibitory concentration (MIC) of 0.6 ppm. A plot of alcohol chain length versus MIC showed a highly significant (P < 0.01) cubic function.