Nicoletta Murru

Occurrence and distribution of polycyclic aromatic hydrocarbons in mussels from the gulf of Naples, Tyrrhenian Sea, Italy.

To assess the potential impact of the industrial activity on food safety and risk for consumers, the aim of the study was to evaluate the levels of 14 polycyclic aromatic hydrocarbons (PAH) in 69 samples of wild and farm Mytilus galloprovincialis, collected in sites of coast of Gulf of Naples, Tyrrhenian Sea. All hydrocarbons were found in samples. Higher levels of pyrolytic PAHs were in wild than in farm mussels. Benzo(a)pyrene exceeded the Regulation (EC) n.835/11 levels of 1 μg/kg in 15 samples (71.42%) of wild and 25 samples (65.79%) of farm mussels. System of sum of 4 hydrocarbons exceeded the law level in 15 samples (71.42%) of wild and 21 samples (55.26%) of farm mussels. Wild mussel levels showed a potential impact of pyrolytic sources of PAH on food safety. Occurrence of carcinogenic PAHs should be a cause for concern, in areas where the mussels are being farmed for human consumption.

Ozone Decontamination of Poultry Meat and Biogenic Amines as Quality Index

To assure food safety in poultry meat the European Regulation does not authorize any decontamination treatment. Ozone has a strong oxidizing nature that makes it a useful tool for the inactivation of microorganisms. Aim of this study was to evaluate the effects of an experimental ozone gaseous treatment and production of the biogenic amines putrescine and cadaverine, as freshness index, during the storage of chilled poultry carcasses. Amines were extracted with perchloric acid, derivative with dansyl chloride, separated using a reversed- phase high-performance liquid chromatographic method, and detected by fluorescence. The results showed a reduction of microbial contamination as effect of the experimental ozone treatment of carcasses. In simply chilled poultry meat (Lot C control) a significant increases of putrescine and cadaverine at 15th days of storage. At 20t day higher levels of putrescine (53,63 mg/kg) and cadaverine (175,20 mg/kg) occurred in Lot C than in treated poultry meat of Lot A. Ozone decontamination resulted in lower levels of putrescine (32,37 mg/kg) and cadaverine (132,30 mg/kg), and in Lot A the shelf life was 6 days longer than in Lot C. If authorized, an ozone treatment during the storage of chilled poultry meat can induce a reduction of microbial contamination. Putrescine and cadaverine levels appeared to be useful to control the effectiveness of the ozone treatment on meat quality, and may be useful as quality index to highlight the loss of poultry meat freshness, before sensorial meat changes during storage of chilled poultry meat.

Biogenic amines profile in processed bluefin tuna (Thunnus thynnus) products

The aim of this study was to evaluate the behavior of biogenic amines (BAs), especially histamine (HIS), and its correlation with pH, water activity (Aw), sodium chloride (NaCl), and microbiological parameters in innovative bluefin tuna (Thunnus thynnus) – raw, salted, seasoned and cooked products. The sensory analysis showed that this seafood typology, especially the pressed and cooked products, could be accepted willingly by consumer. The results showed amine profile trends that are similar to those observed during ripening and seasoning of pig meat products; HIS levels were found to be lower than the limits set by EU legislation in all products and during the whole storage period. To ensure the safety of the analyzed products, despite using raw materials of excellent quality, it is important to select process parameters that reduce the BA production.

Multiplex PCR to detect bacteriophages from natural whey cultures of buffalo milk and characterisation of two phages active against Lactococcus lactis, фApr-1 and фApr-2

This work investigated bacteriophage induced starter failures in artisanal buffalo Mozzarella production plants in Southern Italy. Two hundred and ten samples of whey starter cultures were screened for bacteriophage infection. Multiplex polymerase chain reaction (PCR) revealed phage infection in 28.56% of samples, all showing acidification problems during cheese making. Based on DNA sequences, bacteriophages for Lactococcus lactis (L. lactis), Lactobacillus delbruekii (L. delbruekii) and Streptococcus thermophilus (S. thermophilus) were detected. Two phages active against L. lactis, ΦApr-1 and ΦApr-2, were isolated and characterised. The genomes, approximately 31.4 kb and 31 kb for ΦApr-1 and ΦApr-2 respectively, consisted of double-stranded linear DNA with pac-type system. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‑PAGE) showed one major structural protein of approximately 32.5 kDa and several minor proteins. This is the first report of phage isolation in buffalo milk and of the use of multiplex PCR to screen and study the diversity of phages against Lactic Acid Bacteria (LAB) strains in artisanal Water Buffalo Mozzarella starters.

Screening of oxalate degrading lactic acid bacteria of food origin

A screening for oxalate degrading abilities was initially carried on within Lactic Acid Bacteria cultures of different food origin. Seventy-nine strains were drop-inoculated onto MRS agar plates containing calcium oxalate. By comparing colonies diameters, 31 strains were used to inoculate, in parallel, MRS and MRS modified by sodium oxalate addition. Differences in the strains’ growth were assessed by colony forming unit counts. For two strains, the growth in oxalate enriched medium was significantly higher; while, for eleven strains an opposite behaviour was recorded. Two strains – probiotic Lactobacillus rhamnosus LbGG and Enterococcus faecalis 59 – were chosen. The first strain appeared to be able to metabolize oxalate more efficiently than the other tested cultures, while strain 59 appeared unable to gather advantage by oxalates and, indeed, appeared to be inhibited by the salt presence in the medium. Outcomes revealed that higher glucose concentrations may favour oxalates utilization. In MRS with oxalate, but without glucose, citrate was completely metabolized. Evaluation along time confirmed that the oxalate degradation is more significant in presence of glucose. Outcomes may represent a good start for the development of a safe and even probiotic culture able to lower the oxalates content of food.

Persistence of bacterial indicators and zoonotic pathogens in contaminated cattle wastes

BackgroundManure can provide a favourable environment for pathogens’ survival. De-contamination may be conducted by extended storage, until field conditions are suitable for application to land as source of agricultural nutrients.ResultsThe hygienic evaluation of manure and slurry coming from a plant that collects cattle livestock wastes from a big slaughterhouse was carried out. Samples were even collected from spillages in the area around the plant. Microbial analyses highlighted the massive presence of faecal indicators in all samples: mean counts of Escherichia coli and enterococci were always above EU limits for marketable processed manure products.Cultures referable to the genus Brucella spp. were recorded in two samples of fresh manure but not in the aged ones. Conventional isolation techniques failed to detect members of the Mycobacterium genus, while by means of IS900 and F57 PCR real-time system on DNA directly extracted from environmental samples, the pathogen was detected in all cases.ConclusionsThoughtful design of manure storage infrastructure is critical to prevent spills and over-topping of an open structure. The documented overload situation seems to lay the basis for an ongoing environmental contamination by enteric organisms and opportunistic pathogens circuit faecal-oral route. Moreover, the type of wastes analysed during this study, namely a mixture of fresh cattle manure, bedding and rumen content, needs a longer storage period or, alternatively, of specific chemical, biological or thermal treatments for stabilization.

Dynamics of lactic acid bacteria in “Pecorino di Tramonti”—a ewe’s milk cheese—with particular emphasis on enterococci: a preliminary study

The autochthonous lactic microflora involved in the production of the artisanal “Pecorino di Tramonti” cheese—a ewe’s milk cheese—was evaluated at the date of production and during ripening. Two batches, spicy and mild (not spicy) cheese, of premium quality Pecorino di Tramonti were produced from raw ewe’s milk without starter cultures, according to a very traditional technique. Lactic acid bacteria were monitored by counting on selective media. Counts for mesophilic rods and cocci on MRS and LM17 ranged from 6 to 8 Log CFU/g, respectively, during the entire ripening, but different growth trends could be observed between the two kinds of cheese. Enterococcal levels increased during the 1st month and decreased thereafter throughout ripening. A total of 169 cultures was selected randomly and identified by numerical analysis of ribopatterns. Ribotypes could be grouped in five clusters corresponding to different taxons. Enterococcusfaecium proved to be the dominant species, followed by Lactococcuslactis subsp. lactis, L. lactis subsp. cremoris, Enterococcus faecalis and Enterococcus durans.

Preliminary study on physicochemical and biochemical stress markers at poultry slaughterhouse

Pre-slaughter stress can result in variations in the glycogen storage and metabolic changes of muscle, responsible for quality poultry meat. Aim of this study was to investigate, as pre-slaughter stress markers and quality meat, physicochemical (pH), biochemical (muscle glycogen content), and chemical (super oxides free radicals) parameters. The carcass quality, as incidence of individual carcass defects, was also evaluated. Twenty broilers were processed with two different electrical stunning: high (250 Hz; 640 mA; 60V) (Lot C or control) and low (150 Hz; 360 mA; 60 V) (Lot A) frequency and intensity, using sinusoidal alternating current. As preliminary results, the use of low frequency and intensity induced faster pH decline post mortem and adequate acidification of pH at 3 hours (6.49 Lot C; 6.37 Lot A), better muscle glycogen reserve (0.770 μL/50 mL Lot C; 1.497 μL/50mL Lot A), and lightly more rapid muscle oxidation (IDF: 0.109 Lot C; 0.122 Lot A), (FOX: 0.131 MeqO2/kg Lot C; 0.140 MeqO2/kg Lot A). The incidence of individual carcass defects sufficient to cause downgrading or rejection, both in Lot C and Lot A, was generally low. In a multidisciplinary approach, to assess animal welfare and quality poultry meat, additional and feasible parameters should be implemented. Monitoring of pH, muscle glycogen reserve and superoxide free radical production measurements might be markers easier to use, routinely, in practice at abattoir. Further studies are needed to evaluate the usefulness of these parameters.

Study on the effects of electrical stunning parameters for broilers on biochemical and histological markers of stress and meat quality

This study was designed to investigate physicochemical (pH, peroxides) and histological parameters (glycogen reserve, muscle damages), as pre-slaughter stress markers and quality meat evaluators. Ross commercial broilers was processed, either without stunning (NS Lot), or by combining two current levels of 200 mA, 67 V (HV Lot), and 200 mA, 53 V (MV Lot); with two frequencies of 1000 Hz and 800 Hz, using sinusoidal alternating current. The use of high frequency (800 and 1000 Hz) induced the fastest pH decline, already at 3 h postmortem, in Pectoralis major and Quadriceps femoris of MV and HV Lot carcasses (P < 0.05). Moreover HV carcasses showed a lesser production of superoxide free radicals than the NS Lot and MV Lot carcasses (P < 0.05). Changes in the glycogen reserve and the histological muscle damages did not show significant differences in the analysed Lots. The incidence of individual carcass defects, sufficient to cause downgrading or rejection was generally low in each Lot. To assess animal welfare and quality poultry meat the pH monitoring and measurement of superoxide radical production, as additional and feasible parameters, might be markers easier to use in practice at abattoir.

Shelf life of anchovy products (Engraulis encrasicolus): evaluation of sensory, microbiological and chemical properties

Fishery products have always been an important food in Italy. In the past, increased consumption was mainly due to the good quality of the products, easiness of use and their beneficial effects on health. Recently, owing to the national financial crisis, there has been a decline in the consumption of fish. In fact, in 2013, according to data from ISMEA, the consumption of fresh fish suffered a sharp contraction (-5%). This decline also concerns anchovy (Engraulis encrasicolus). This species, partly because of its low price, is a mainstay of traditional Italian food. The aim of this study was to evaluate sensorial, chemical and microbiological properties of anchovy-based (Engraulis encrasicolus) products during storage at 4 and -20°C. Fresh anchovies, obtained from the wholesale fish market of Pozzuoli (Southern Italy) were cut into small pieces and hand-prepared using bread, eggs, cheese and lemon juice. Samples were analysed after 0, 2, 4, 6 and 8 days of storage at 4°C. An aliquot was quickly frozen and analysed after 34 days at -20°C. Sensory assessment, microbiological (specific spoilage organisms, Listeria spp. and Salmonella spp.) and chemical (histamine, total volatile basic nitrogen, trimethylamine, thiobarbituric acid, pH and aw) analyses were performed. Results showed that the shelf life of anchovy products was less than 5 days for the samples stored at 4°C. At -20°C, all anchovies preparations showed good sensory, microbiological and chemical properties for 34 days.