Antimicrobial action of citrus oils.

inhibitory effect of essential oils of orange
and lemon oil and the antibiotics tylosin and nisin was tested
on bacteria and fungi in nutrient media. Though the degree
of inhibition varied with the culture, orange oil was a more
effective antimicrobial agent than lemon oil. All other conditions
being identical, 2,000 ppm of orange oil had an effect
similar to 10 ppm of tylosin, on all the gram-positive cultures
tried, including the spores of Bacillus mbtilis. Moreover,
orange oil was the only additive that showed inhibition of
growth of the gram-negative cultures, excepting Serratia
nzarcescens. Yeasts, in general, were more sensitive than bacteria
to orange oil, the effective dose being 500 ppm, at a
cell concentration of 1 million/ml. This was a definite advantage
over the antibiotics, which had no action on fungi.
Though not so sensitive as the yeasts, the molds were also
suppressed by orange oil at 2,000 ppm. The possibility of
using orange oil as a preservative in foods is indicated.