Chemical Profile, Antioxidant and Antibacterial Activities of Achillea moschata Wulfen, an Endemic Species from the Alps.

Aerial parts of Achillea moschata Wulfen (Asteraceae) growing wild in the Italian Rhaetian Alps were investigated to describe, for the first time, their phenolic content, as well as to characterize the essential oil. Inspection of the metabolic profile combining HPLC-DAD and ESI-MS/MS data showed that the methanol extract contained glycosylated flavonoids with luteolin and apigenin as the main aglycones. Among them, the major compound was 7-O-glucosyl apigenin. Caffeoyl derivates were other phenolics identified. The essential oil obtained by steam distillation and investigated by GC/FID and GC/MS showed camphor, 1,8-cineole, and bornylacetate as the main constituents. The antioxidant capacity of three different extracts with increasing polarity and of the essential oil was evaluated by employing ABTS·+ and DPPH· radical scavenging assays. The methanolic extract was the only significantly effective sample against both synthetic radicals. All samples were also tested against Gram-positive (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa) bacterial species using the disk diffusion assay. The non-polar extracts (dichloromethane and petroleum ether) and the essential oil possessed a broad spectrum of antimicrobial activity expressed according to inhibition zone diameter (8-24 mm).

Regulations relating to mycotoxins in almonds in European context.

Mycotoxins are secondary metabolites produced by several species of fungi and having a toxic effect on humans and farm animals. In particular, almonds, a rich source of nutrients and phytochemicals, can be contaminated by aflatoxins, one of the most important mycotoxins, mainly produced by Aspergillus flavus and Aspergillus parasiticus. The reference regulations in this field are continuously improved and updated worldwide. This paper reports the current state of the European regulations on aflatoxins in almonds concerning the limits, and the procedures for performing official controls and for import.

Ginger and parsley essential oils: chemical composition, antimicrobial activity, and evaluation of their application in cheese preservation.

Chemical composition and in vitro antimicrobial activity of parsley [Petroselinum crispum (Mill.) Fuss] and ginger (Zingiber officinale Roscoe) essential oils from store-bought parsley plants and ginger rhizomes were evaluated. A sensory analysis was performed on aged cheese slices treated with a mix of each essential oil and seed oil. Parsley essential oil was selected as the best compromise between sensory influence and antimicrobial activity and tested to evaluate its antifungal effects on cheese slices experimentally contaminated with Aspergillus flavus. Monoterpenes and α-zingiberene were the most abundant compounds in parsley and ginger essential oil, respectively. Both essential oils showed in vitro antimicrobial activity against different fungal species while only a bacterial strain (Enterococcus faecalis) was sensible to ginger essential oil. Only the cheese slices treated with parsley essential oil were appreciated by the panellists and its use has been effective in preventing the A. flavus growth in cheese.

Screening of Different Essential Oils Based on Their Physicochemical and Microbiological Properties to Preserve Red Fruits and Improve Their Shelf Life.

Strawberries and raspberries are susceptible to physiological and biological damage. Due to the consumer concern about using pesticides to control fruit rot, recent attention has been drawn to essential oils. Microbiological activity evaluations of different concentrations of tested EOs (cinnamon, clove, bergamot, rosemary and lemon; 10% DMSO-PBS solution was used as a diluent) against fruit rot fungal strains and a fruit-born human pathogen (Escherichia coli) indicated that the highest inhibition halos was found for pure cinnamon and clove oils; according to GC-MS analysis, these activities were due to the high level of the bioactive compounds cinnamaldehyde (54.5%) in cinnamon oil and eugenol (83%) in clove oil. Moreover, thermogravimetric evaluation showed they were thermally stable, with temperature peak of 232.0 °C for cinnamon and 200.6/234.9 °C for clove oils. Antibacterial activity evaluations of all tested EOs at concentrations from 5-50% (v/v) revealed a concentration of 10% (v/v) to be the minimum inhibitory concentration and minimum bactericidal concentration. The physicochemical analysis of fruits in an in vivo assay indicated that used filter papers doped with 10% (v/v) of cinnamon oil (stuck into the lids of plastic containers) were able to increase the total polyphenols and antioxidant activity in strawberries after four days, with it being easier to preserve strawberries than raspberries.

Atmosferic pressure non-thermal plasma: Preliminary investigation.

Antibacterial activity of atmosferic pressure non-thermal plasma (APNTP) was assessed for bacterial, yeast and mold strains. This investigation is to be considered preliminary: a second step is envisaged in which the efficacy of the technique and the device will be assessed directly on food of animal and plant origin. The strains (ATCC or wild type) of Listeria innocua, Escherichia coli, Salmonella thyphimurium, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Proteus mirabilis (bacteria); Alternaria alternata, Aspergillus flavus, Cladosporium herbarum, Fusarium graminearum, Geotrichum candidum, Penicillium roqueforti, Rhizopus nigricans (moulds); Candida parapsilosis and Candida albicans (yeasts) were subjected to plasma plume generated by the action of electric fields with a gas mixture (oxygen and helium) delivered for 5 min at a distance of 2 cm. Types of experiments were listed as following: microorganism at concentration 1×10^8 and 1×104 cfu on PCA (Plate Count Agar); Listeria innocua and Salmonella thiphymurium at concentration 1×10^4 cfu on semi-synthetic and synthetic medium; mycetes (moulds and yeasts) at concentration 1×10^8 and 1×10^4 cfu on SDA (Sabouraud Dextrose Agar). The results obtained on the bacteria subjected to atmospheric cold plasma were evident on all the strains tested except for Proteus mirabilis (1×10^8 cfu), most evident at a concentration of 1×10^4 cfu, not only on culture media PCA but also on semi-synthetic medium and jelly meat-PCA medium. In spite of bacterial results, treatment with plasma plume did not decrease or inhibit of fungal growth. That means plasma plume was neither fungicidal nor fungistatic activities.

Inhibitory activity of stilbenes against filamentous fungi.

Stilbenoids (resveratrol and its derivatives) are secondary metabolites produced by plants as defence mechanism to microbial infection. These compounds are known for their anti-inflammatory action and health benefits in preventing a wide range of disorders (e.g. cancer and cardiovascular diseases). However, their antimicrobial properties are less investigated. A series of 8 stilbenoid compounds were synthesized and their antifungal activity against 19 wild strains of filamentous fungi and yeasts (isolated from the environment and food) was tested in vitro. Using an agar diffusion assay, compounds were tested at the concentration of 100 µg/ml on filamentous fungi and yeasts at 104 CFU/ml. The results showed that tested derivatives possess moderate antifungal activity: in particular, monomeric stilbenoids 3'-hydroxy-pterostilbene and piceatannol, and dimeric stilbenoids (±)-trans-δ-viniferin and pallidol were active against mycotoxigenic fungi.

Thymus vulgaris L. as a possible effective substitute for nitrates in meat products.

Nitrates are chemicals found naturally in some foods such as fruit and vegetables or added to others, especially meats, as a preservative. Their use as additives is regulated by European Commission to avoid any risk for human health. In order to reduce or replace the use of these compounds, we investigated the bacteriostatic/bactericidal activity of the essential oil of Thymus vulgaris L. against Listeria innocua, a nonpathogenic microorganism with the same morpho-cultural traits of L. monocytogenes. The study was carried out in vitro and in vivo on processed meat products, i.e. mature salami, by using thyme essential oil. Although the results are preliminary, the antilisterial activity of the thyme essential oil was shown to be similar to that of nitrates.

Functional characterization of Lactobacillus plantarum ITEM 17215: A potential biocontrol agent of fungi with plant growth promoting traits, able to enhance the nutritional value of cereal products.

In this work, we explored the potential of 25 Lactobacillus plantarum strains isolated from cereals and milk-based products, testing characteristics related to antifungal activity and to nutritional quality. The tested strains demonstrated interesting beneficial traits, such as the ability to utilize fructo-oligosaccharides, prebiotic substances that help probiotic microorganisms to grow in the human gut, and to reduce phytate, an antinutrient present in cereal sector. Regarding mould inhibition, we highlighted the ability of the strains to inhibit Penicillium roqueforti, Mucor circinelloides and mycotoxinogenic moulds associated with cereal grains as Aspergillus flavus, A. niger, Fusarium verticillioides. Moreover, a moderate reduction of the bioavailability of aflatoxin AFB1 was detected. The selected L. plantarum strain ITEM 17215, showed a strong inhibitory ability towards fungal growth and was able to produce 1,2-dihydroxybenzene, benzoic acid, p-hydroxyphenyllactic acid and 3-phenyllactic acid. The latter compound, already described as efficient antifungal inhibitor, was the most abundant and its concentration was further increased by adding phenylalanine and phenylpyruvic acid in the growth medium. The metabolites produced by strain ITEM 17215 could also be related to the ability of the strain to induce cereal germination and promote plant growth. This aspect, not yet investigated in L. plantarum, could have interesting applications in the agro-food sector.

A survey of the mycobiota associated with larvae of the black soldier fly (Hermetia illucens) reared for feed production.

Feed security, feed quality and issues surrounding the safety of raw materials are always of interest to all livestock farmers, feed manufacturers and competent authorities. These concerns are even more important when alternative feed ingredients, new product developments and innovative feeding trends, like insect-meals, are considered. The black soldier fly (Hermetia illucens) is considered a good candidate to be used as feed ingredient for aquaculture and other farm animals, mainly as an alternative protein source. Data on transfer of contaminants from different substrates to the insects, as well as the possible occurrence of toxin-producing fungi in the gut of non-processed insects are very limited. Accordingly, we investigated the impact of the substrate/diet on the intestinal mycobiota of H. illucens larvae using culture-dependent approaches (microbiological analyses, molecular identification through the typing of isolates and the sequencing of the 26S rRNA D1/D2 domain) and amplicon-based next-generation sequencing (454 pyrosequencing). We fed five groups of H. illucens larvae at the third growing stage on two substrates: chicken feed and/or vegetable waste, provided at different timings. The obtained results indicated that Pichia was the most abundant genus associated with the larvae fed on vegetable waste, whereas Trichosporon, Rhodotorula and Geotrichum were the most abundant genera in the larvae fed on chicken feed only. Differences in the fungal communities were highlighted, suggesting that the type of substrate selects diverse yeast and mold genera, in particular vegetable waste is associated with a greater diversity of fungal species compared to chicken feed only. A further confirmation of the significant influence of diet on the mycobiota is the fact that no operational taxonomic unit common to all groups of larvae was detected. Finally, the killer phenotype of isolated yeasts was tested, showing the inhibitory activity of just one species against sensitive strains, out of the 11 tested species.

Evaluation of Antifungal Effect of Gaseous Ozone in a Meat Processing Plant.

Ozone is already known as effective food/environmental disinfection agent, thanks to its oxidative action towards microbial cell components. Bactericidal effect of ozone is well documented, while data concerning its inhibitory activity towards fungi are still ambiguous. Our study aims to evaluate the antimicrobial activity of gaseous ozone towards potentially contaminant fungi in a meat production plant in real working conditions. M2 and M5S5 plates were inoculated with Aspergillus niger, Penicillium roqueforti, Mucor racemosus, Saccharomyces cerevisiae strains and positioned in a deboning room, where gaseous ozone was dispensed throughout the night (until a maximum concentration of 20 ppm). Nine different points were chosen, based on height and distance from the ozone dispenser. After the treatment, the presence of strains growth was evaluated. Gaseous ozone did not show any inhibitory activity against mould strains, as optimum growth during all the trials was observed. An appreciable and constant microbicidal effect against S. cerevisiae was evidenced, with a mean value of 2.8 Log reduction. Our results suggest the importance of the definition of environmental and technical use conditions in order to optimise the antimicrobial efficacy of ozone in real working situations in food industries.

Secondary Metabolites from Penicillium roqueforti, A Starter for the Production of Gorgonzola Cheese.

The presence of mold in food, although necessary for production, can involve the presence of secondary metabolites, which are sometimes toxic. Penicillium roqueforti is a common saprophytic fungus but it is also the essential fungus used in the production of Roquefort cheese and other varieties of blue cheese containing internal mold. The study was conducted on industrial batches of Penicillium roqueforti starters used in the production of the Gorgonzola cheese, with the aim to verify the production of secondary metabolites. Nine Penicillium roqueforti strains were tested. The presence of roquefortine C, PR toxin and mycophenolic acid was tested first in vitro, then on bread-like substrate and lastly in vivo in nine cheese samples produced with the same starters and ready to market. In vitro, only Penicillium out of nine produced roquefortine C, four starters showed mycophenolic acid production, while no significant amounts of PR toxin were detected. In the samples grown on bread-like substrate, Penicillium did not produce secondary metabolites, likewise with each cheese samples tested. To protect consumers' health and safety, the presence of mycotoxins needs to be verified in food which is widely consumed, above all for products protected by the protected denomination of origin (DOP) label (i.e. a certificate guaranteeing the geographic origin of the product), such as Gorgonzola cheese.