Evaluation of five essential oils for the control of food - spoilage and mycotoxin producing fungi

The inhibition of growth and aflatoxin production by essential oils (EOs) of cinnamon, clary sage, juniper, lemon and marjoram were investigated on food-spoilage fungi Aspergillus parasiticus var.globosus, Fusarium graminearum and Fusarium culmorum. The antifungal effect of the EOs was observed by determination of growth-rate (mm/day) and antifungal index (%) using reversed Petri-dish method. Aflatoxin production of A. parasiticus was monitored by thin layer chromatography (TLC). The growth of A. parasiticus was significantly decreased (P<0,001) by marjoram and clary sage EOs. TLC results revealed only a slight effect on aflatoxin production: cinnamon and clary sage EOs found to decrease the amount of aflatoxin B1 and G2. F. graminearum and F. culmorum showed almost similar response to the EOs. In both cases cinnamon EO caused a total inhibition of growth, while lemon EO was ineffective. Juniper significantly (P<0,003) inhibited the growth of F. culmorum but had no effect on F. graminearum. The EOs tested in this study may be potential antimicrobial compounds for use as food preservatives and anti-aflatoxin agents

Activity of Binary Combinations of Natural Phenolics and Synthetic Food Preservatives against Food Spoilage Yeasts

Natural compounds are a suitable alternative to synthetic food preservatives due to their natural origin and health-promoting properties. In the current study, phenolic–phenolic and phenolic–synthetic combinations were tested for their antibiofilm formation, anti-planktonic growth, and anti-adhesion properties against Debaryomyces hansenii, Wickerhamomyces anomalus (formerly Pichia anomala), Schizosaccharomyces pombe, and Saccharomyces cerevisiae. The phenolics were vanillin and cinnamic acid, while the synthetic preservatives were sodium benzoate, potassium sorbate, and sodium diacetate. The vanillin–cinnamic acid combination had synergistic effect in all the tested yeasts for the biofilm inhibition with a fractional inhibitory concentration index (FICI) of ≤0.19 for W. anomalus, 0.25 for S. pombe, 0.31 for S. cerevisiae, and 0.5 for D. hansenii. Most of the phenolic–synthetic combinations had indifferent interaction regarding biofilm formation. The vanillin–cinnamic acid combination also had higher activity against spoilage yeasts adhesion on the abiotic surface and planktonic growth compared to the phenolic–synthetic combinations. For the phenolic–synthetic anti-planktonic activity, synergistic interaction was present in all the vanillin–synthetic combinations in S. pombe, vanillin–sodium benzoate and vanillin–potassium sorbate in S. cerevisiae, vanillin–sodium benzoate in W. anomalus, and cinnamic acid–sodium diacetate in S. pombe. These results suggest a novel antimicrobial strategy that may broaden the antimicrobial spectrum and reduce compound toxicity against food spoilage yeasts

Preservation effect of cinnamon and clove essential oil vapors on shelled walnut

Shelled walnut (Juglans regia) kernels are prone to rancidity during storage. In this study we examined the preservation effect of cinnamon and clove essential oil (EO) vapors compared to cold storage and vacuum packaging by measuring the hexanal content, indicating rancidity, in stored walnut kernels. Odor and taste of stored shelled walnut was investigated by sensory evaluation and by measuring residues of the main EO components in the kernels. During storage under EO vapors, cinnamaldehyde and eugenol were absorbed on the surface of walnuts in a time-dependent manner changing the odor and taste of the kernels. Clove (Syzygium aromaticum) EO prevented rancidity and EO treated kernels were rated as acceptable by the sensory panel while cinnamon EO treatment increased rancidity compared to the other treatments and the control samples

Activity of Binary Combinations of Natural Phenolics and Synthetic Food Preservatives against Food Spoilage Yeasts

Natural compounds are a suitable alternative to synthetic food preservatives due to their natural origin and health-promoting properties. In the current study, phenolic–phenolic and phenolic–synthetic combinations were tested for their antibiofilm formation, anti-planktonic growth, and anti-adhesion properties against Debaryomyces hansenii, Wickerhamomyces anomalus (formerly Pichia anomala), Schizosaccharomyces pombe, and Saccharomyces cerevisiae. The phenolics were vanillin and cinnamic acid, while the synthetic preservatives were sodium benzoate, potassium sorbate, and sodium diacetate. The vanillin–cinnamic acid combination had synergistic effect in all the tested yeasts for the biofilm inhibition with a fractional inhibitory concentration index (FICI) of ≤0.19 for W. anomalus, 0.25 for S. pombe, 0.31 for S. cerevisiae, and 0.5 for D. hansenii. Most of the phenolic–synthetic combinations had indifferent interaction regarding biofilm formation. The vanillin–cinnamic acid combination also had higher activity against spoilage yeasts adhesion on the abiotic surface and planktonic growth compared to the phenolic–synthetic combinations. For the phenolic–synthetic anti-planktonic activity, synergistic interaction was present in all the vanillin–synthetic combinations in S. pombe, vanillin–sodium benzoate and vanillin–potassium sorbate in S. cerevisiae, vanillin–sodium benzoate in W. anomalus, and cinnamic acid–sodium diacetate in S. pombe. These results suggest a novel antimicrobial strategy that may broaden the antimicrobial spectrum and reduce compound toxicity against food spoilage yeasts

Anti-listerial effect of selected essential oils and thymol

The anti-listerial effect of marjoram, thyme essential oils (EOs) and thymol on Listeria monocytogenes inoculated chicken breast fillets was investigated. Before inoculation the fillets were pretreated by washing or not under running tap water. Inoculated samples were kept at 6 °C for 24 h to allow the growth of L. monocytogenes. After this, the fillets were put in marinating solutions containing salt (5%) and EOs or thymol in MIC/2 concentration established in vitro. Total germ count (TGC) and L. monocytogenes count was monitored on the meat surface and in the marinating solutions following 24 and 48 h storage at 6 °C. Thyme and thymol reduced significantly Listeria cell count (1–3 log CFU) in both samples. They also gave good flavour to the fried meat. The doses of EOs used were optimal for antimicrobial efficiency and had a pleasant flavour effect. Washing was not efficient in reducing total germ count

Preservation effect of cinnamon and clove essential oil vapors on shelled walnut

Shelled walnut (Juglans regia) kernels are prone to rancidity during storage. In this study we examined the preservation effect of cinnamon and clove essential oil (EO) vapors compared to cold storage and vacuum packaging by measuring the hexanal content, indicating rancidity, in stored walnut kernels. Odor and taste of stored shelled walnut was investigated by sensory evaluation and by measuring residues of the main EO components in the kernels. During storage under EO vapors, cinnamaldehyde and eugenol were absorbed on the surface of walnuts in a time-dependent manner changing the odor and taste of the kernels. Clove (Syzygium aromaticum) EO prevented rancidity and EO treated kernels were rated as acceptable by the sensory panel while cinnamon EO treatment increased rancidity compared to the other treatments and the control samples