The potential application of plant essential oils as natural food preservatives in soft cheese

Investigations were carried out to assess the efficiency of four plant esse ntial oils, bay, clove, cinnamon and thyme as natural food preservatives. T he effect of the plant essential oils at concentrations of 0.1, 0.5 and 1% was studied in low-fat and full-fat soft cheese against Listeria monocytoge nes and Salmonella enteritidis at 4 degrees and 10 degreesC respectively ov er a 14-day period. The composition of the cheese was shown to be an import ant factor in determining the effectiveness of the plant essential oils. In the low-fat cheese, all four oils at 1% reduced L. monocytogenes to less t han or equal to 1.0 log(10) cfu ml(-1) In contrast, in the full-fat cheese, oil of clove was the only oil to achieve this reduction. Oil of thyme prov ed ineffective against S. enteritidis in the full-fat cheese, yet was equal ly as effective as the other three oils in the lowfat cheese, reducing S. e nteritidis to < 1.0 log(10) cfu ml(-1) from day 4 onwards. It is concluded that selected plant essential oils can act as potent inhibitors of L. monoc ytogenes and S. enteritidis in a food product. (C) 2001 Academic Press.