Antioxidant and antimicrobial preservatives: Properties, mechanism of action and applications in food - a review.

In the food industry, there is a need to use the properties of antioxidants and antimicrobials effectively to prevent microbial growth in foods, as well as to retard the oxidation of fats to delay rancidity. Nevertheless, the emerging concern about the negative effects of synthetic antioxidants and antimicrobials on consumers' health along with the advantages of natural substances have led to more fundamental research to investigate the mechanism of action and toxicity of natural antioxidants and antimicrobials. There is also a need to establish in each country an appropriate regulatory scheme to assure consumers of the safety and efficacy of these materials. Thus, this present review provides a detailed overview of the different antioxidant and antimicrobial groups, focusing on their properties, mechanism of action, and applicability in the food industry to be a guide for students and researchers.

In Vitro Study of the Antifungal Activity of Essential Oils Obtained from Mentha spicata, Thymus vulgaris, and Laurus nobilis.

BACKGROUND: The aim of this study was to determine the antifungal activity of the essential oils isolated from three aromatic plants against 13 filamentous fungal strains. METHODS: The major constituents of Mentha spicata, Thymus vulgaris, and Laurus nobilis essential oils were carvone (52.2%), linalool (78.1%), and 1,8-cineole (45.6%), respectively. There are also some patents suggesting the use of essential oils as natural and safe alternatives to fungicides for plant protection. RESULTS: In the present work, M. spicata essential oil exhibited the strongest activity against all tested fungi in which Fusarium graminearum, F.moniliforme, and Penicillium expansum were the most sensitive to mint oil with lower minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values of 2.5 µL mL-1 (v/v). Thymus vulgaris essential oil was less active compared to the oil of M. spicata. Aspergillus ochraceus was the most sensitive strain to thyme oil with MIC and MFC values of 2.5 and 5 µL mL-1, respectively. Thymus vulgaris essential oil also exhibited a moderate fungicidal effect against the tested fungi, except for A. niger (MFC >20 µL-1). L. nobilis essential oil showed a similar antifungal activity with thyme oil in which A. parasiticus was the most resistant strain to this oil (MFC >20 µL mL-1). CONCLUSION: Our findings suggested the use of these essential oils as alternatives to synthetic fungicides in order to prevent pre-and post-harvest infections and ensure product safety.

Effect of Mentha spicata L. and Artemisia campestris extracts on the shelf life and quality of vacuum-packed refrigerated sardine (Sardina pilchardus) fillets.

The present study investigated the effects of ethanolic extracts obtained from Mentha spicata and Artemisia campestris on the shelf life and the quality of vacuum-packed sardine fillets stored at 3 ± 1°C for a period of 21 days. The three groups were tested were VC, control group; VM, group treated with 1 % mint extract; and VA, group treated with 1 % artemisia extract. The observed shelf life of sardine fillets was 10 days for control samples, whereas the combination of vacuum packaging with mint and artemisia extracts extended the product's shelf life to 17 days. Among the chemical indices determined, the thiobarbituric acid-reactive substances values were significantly lower in VM samples. Total volatile base nitrogen was maintained at low levels in VA samples until 17 days of chilled storage. Results of aerobic plate counts and coliform counts showed the existence of a reduced growth in VA group, whereas lactic acid bacteria did not show a significant difference among groups. Natural extract treatments combined with vacuum packaging showed lower microbiological and chemical indices, indicating that the presence of phenolic compounds in mint and artemisia extracts and the removal of oxygen in the pack retarded lipid oxidation and reduced the growth of microorganisms, which resulted in preventing spoilage and extending the product's shelf life.