Inhibitory Effect of Rosemary Essential Oil and Its Nanoemulsion on the Formation of Biogenic Amines by Food-Borne Pathogens and Fish Spoilage Bacteria

Abstract

The effect of nanoemulsions based on rosemary essential oil (BNE) and its purified version (BEO) on the growth of fish spoilage bacteria (P. luteola, P. damselae, V. vulnificus, E. faecalis, S. liquefaciens, and P. mirabilis) and foodborne pathogens (S. Paratyphi A, S. aureus, K. pneumoniae, and E. faecalis) and their biogenic amine formation were investigated in tyrosine decarboxylase broth (TDB) using HPLC method. The flavour compounds of extracted BEO were determined using GC-MS. Physical properties of BNE (viscosity, thermodynamic stability, droplet size, and surface tension) were analysed. Tween 80, BEO, and BNE were inhibitory effects on the growth performances of the pathogenic and spoilage bacteria. Differences in ammonia (AMN) and biogenic amine (BA) production among groups were statistically significant (p<0.05). The highest HIS production was obtained by spoilage E. faecalis (58.76 mg L-1) and the lowest by V. vulnificus (2.29 mg L-1). Almost all other BAs such as PUT, CAD, SPD, and PHEN were formed by pathogens and spoilage groups. S. aureus (143.05-702.88 mg L-1) was the main high tyramine (TYR) producer in TDB. HIS production by V. vulnificus was considerably suppressed in the presence of BNE (p<0.05). Although the effect of treatment groups (Tween 80, BEO, and BNE) varied depending on the bacterial strain and specific amine, all groups generally decreased AMN and BA accumulation by bacteria. Consequently, the results show that all bacteria tested are capable of decarboxylating more than one amino acid and conversion of rosemary oil into nanoemulsion suppressed BA production activity and its nano-form can be used as an alternative antimicrobial agent in processed or packaged fish or food products.