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 essential oils, bay, clove, cinnamon and thyme as natural food preservatives. The 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 monocytogenes and Salmonella enteritidis at 4 degrees and 10 degreesC respectively over a 14-day period. The composition of the cheese was shown to be an important 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 than 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 proved ineffective against S. enteritidis in the full-fat cheese, yet was equally as effective as the other three oils in the lowfat cheese, reducing S. enteritidis 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. monocytogenes and S. enteritidis in a food product. (C) 2001 Academic Press.