Assessment of Antimicrobial Efficiency of Pistacia lentiscus and Fortunella margarita Essential Oils against Spoilage and Pathogenic Microbes in Ice Cream and Fruit Juices

Nowadays, the use of antimicrobial natural agents as alternative food preservatives represents an intriguing case. The purpose of this study was to investigate possible antimicrobial activity of Pistacia lentiscus and Fortunella margarita essential oils (EOs) and to evaluate their commercial potential in the food industry. The main constituents identified by GC/MS in Pistacia lentiscus EO were a-pinene (67.7%), myrcene (18.8%), and β-pinene (3.0%), whereas limonene (93.8%) and myrcene (2.7%) were the dominant compounds in Fortunella margarita EO. The antimicrobial properties were initially assayed and the minimum inhibitory, non-inhibitory, and minimum lethal concentration values against the Escherichia coli, Listeria monocytogenes, Pseudomonas fragi, Aspergillus niger, and Saccharomyces cerevisiae were determined using a previously published model, combining absorbance measurements with the common dilution method and non-linear regression analysis to fit the data. Their efficiency was further validated in ice cream containing 0.2% (w/w) Pistacia lentiscus, 0.006% (w/w) Fortunella margarita EOs and 2% (w/w) aqueous residue of F. margarita EO deliberately inoculated with 4 logcfu/g Escherichia coli, Listeria monocytogenes or Pseudomonas fragi, separately. Similarly, the activity of the oils was monitored in fruit juice (lemon, apple, and blackcurrant) containing 0.2% (w/w) Pistacia lentiscus, 0.006% (w/w) Fortunella margarita EOs and 2% (w/w) aqueous residue of F. margarita EO deliberately spiked with 100 spores/mL of Aspergillus niger or 4 logcfu/mL of Saccharomyces cerevisiae, separately. The results showed that microbial viable counts in the supplemented products ranged at significantly lower levels compared to the control samples during storage. Overall, the data indicated that both EOs constitute effective antimicrobial sources with many potent applications in the food industry.