Effect of the partial replacement of fish meal and oil by vegetable products on performance and quality traits of juvenile shi drum (Umbrina cirrosa L.)

A four-month growth trial was carried out in order to evaluate performance and quality traits of juvenile shi drum fedwith two isonitrogenous and isoenergetic diets having different amounts of vegetable products (Vegetable diet vs. Controldiet). Compared to the Control diet, the Vegetable diet was formulated by increasing the replacement of fish meal (14%)with soybean and cereal products, and fish oil (12%) with a mixture of vegetable oil. On June, 4 groups of 225 fish (2replicates per dietary treatment) were sorted according to live weight and reared in fibreglass tanks over a four- monthlong experimental period. Fish were hand fed to apparent satiety. Offered feed, growth parameters and feed efficiencywere recorded as productive performance. At the end of the trial (October) biometric, chemical and reological traits wereexamined to assess fish quality. The dietary treatments showed similar productive performance. The relatively high inclusionof vegetable sources led to a significant modification of body shape, mesenteric fat and viscera weight. Among qualitytraits, Vegetable diet-fed fish demonstrated a significantly lower whole body and fillet crude protein content.Yellowness value of the cooked fillet was significantly lower in the Control diet-fed fish, whereas fillet texture was similar.The results of this research showed that shi drum is a suitable candidate for Mediterranean marine aquaculture andits dietary formulation might include at least the amount of vegetable sources used in this trial

Contribution of natural milk culture to microbiota, safety and hygiene of raw milk cheese produced in alpine malga

Processing of alpine milk in malga farms is carried out under conditions that can favor contamination by coliforms, coagulase-positive staphylococci, or pathogens such as Listeria monocytogenes. With the aim to improve the hygienic characteristics and safety of cheese produced in four malga farms the use of lyophilized Natural Milk Culture prepared with selected strains was tested.. Two cheesemaking tests were carried out in the same day always starting from the same milk: in the first case following the malga recipe that uses either Natural Whey Culture or without the addition of a starter, in the second one using a Natural Milk Culture. Cheesemaking were carried out in four malga farms located in the west area of Trentino region within the same week. For hygienic and safety evaluation, aerobic colony count, coagulase-positive staphylococci, Escherichia coli, staphylococcal toxins, Listeria monocytogenes, and Salmonella spp, pH and aw were determined in raw milk from evening and morning milking, curd in vat, curd after extraction and two months-ripened cheese. Pathogens or toxins, high values of coagulase- positive staphylococci and E. coli were not found in cheese samples. However, in the curd coagulase-positive staphylococci reached values almost of 5 Log CFU/g in the two malga without starter cultures. The use of Natural Milk Culture reduced E. coli counts. In addition, DNA was extracted from cheese samples and from Natural Milk Culture and the composition of the microbial community determined by Next Generation Sequencing method. The determination of cheese microbial communities demonstrated that the use of Natural Milk Culture exerted different effects in the different malga, in any case preserving bacterial biodiversity

Effect of dietary fat level on carcass traits and flesh quality of European Sea Bass (Dicentrarchus labrax) from mariculture

The study aimed at evaluating the effect of the reduction of dietary fat on juvenile European sea bass nutritional value and quality traits. Fish were reared in floating cages (Trieste Gulf, Italy) from July (11) to October (10). Two isoproteic diets were compared: LF (low fat, EE = 19.4%) vs. HF (high fat, EE = 24.6%). No significantly different growth performance was observed. LF diet-fed fish were characterized by the reduction of celomatic fat (not edible fraction) and by the increase in dressing percentage. The tested dietary fat level also affected both fillet and epiaxial white muscle proximate composition, resulting in a significantly lower fillet lipid concentration in LF diet-fed fish. Dietary treatment influenced cooked fillet colour and texture probably as a consequence of the different intramuscular fat deposition. Fillet from HF-fed fish, in fact, presented higher lightness (L*) value and lower instrumental strengthness

Characterisation of the thermostable protease AprX in strains of Pseudomonas fluorescens and impact on the shelf-life of dairy products: preliminary results

Bacterial proteases are involved in food spoilage and shelf-life reduction. Among the bacterial proteases, a predominant role in spoilage of dairy products seems to be played by the thermostable metallo-protease AprX, which is produced by various strains of Pseudomonas fluorescens. Differences in AprX enzyme activity among different strains were highlighted, but the most proteolytic strains were not identified. In this study, the presence of the aprX gene was evaluated in 69 strains isolated from food matrices and 18 reference strains belonging to the P. fluorescens group ,which had been previously typed by the multi locus sequence typing method. Subsequently, a subset of reference strains was inoculated in ultra-high temperature milk, and the expression of the aprX gene was evaluated at 22 and 6°C. On the same milk samples, the proteolytic activity was then evaluated through Azocasein and trinitrobenzenesulfonic acid solution assays. Finally, to assess the applicability of the former assay directly on dairy products the proteolityc activity was tested on industrial ricotta samples using the Azocasein assay. These results demonstrate the spread of aprX gene in most strains tested and the applicability of Azocasein assay to monitor the proteolytic activity in dairy products

Assessment of chicken breast shelf life based on bench-top and portable near-infrared spectroscopy tools coupled with chemometrics

Abstract Objectives Near-infrared (NIR) spectroscopy is a rapid technique able to assess meat quality even if its capability to determine the shelf life of chicken fresh cuts is still debated, especially for portable devices. The aim of the study was to compare bench-top and portable NIR instruments in discriminating between four chicken breast refrigeration times (RT), coupled with multivariate classifier models. Materials and Methods Ninety-six samples were analysed by both NIR tools at 2, 6, 10 and 14 days post mortem. NIR data were subsequently submitted to partial least squares discriminant analysis (PLS-DA) and canonical discriminant analysis (CDA). The latter was preceded by double feature selection based on Boruta and Stepwise procedures. Results PLS-DA sorted moderate separation of RT theses, while shelf life assessment was more accurate on application of Stepwise-CDA. Bench-top tool had better performance than portable one, probably because it captured more informative spectral data as shown by the variable importance in projection (VIP) and restricted pool of Stepwise-CDA predictive scores (SPS). Conclusions NIR tools coupled with a multivariate model provide deep insight into the physicochemical processes occurring during storage. Spectroscopy showed reliable effectiveness to recognise a 7-day shelf life threshold of breasts, suitable for routine at-line application for screening of meat quality

Agricultural by-products with bioactive effects: A multivariate approach to evaluate microbial and physicochemical changes in a fresh pork sausage enriched with phenolic compounds from olive vegetation water

The use of phenolic compounds derived from agricultural by-products could be considered as an eco-friendly strategy for food preservation. In this study a purified phenol extract from olive vegetation water (PEOVW) was explored as a potential bioactive ingredient for meat products using Italian fresh sausage as food model. The research was developed in two steps: first, an in vitro delineation of the extract antimicrobial activities was performed, then, the PEOVW was tested in the food model to investigate the possible application in food manufacturing. The in vitro tests showed that PEOVW clearly inhibits the growth of food-borne pathogens such as Listeria monocytogenes and Staphylococcus aureus. The major part of Gram-positive strains was inhibited at the low concentrations (0.375–3 mg/mL). In the production of raw sausages, two concentrates of PEOVW (L1:0.075% and L2: 0.15%) were used taking into account both organoleptic traits and the bactericidal effects. A multivariate statistical approach allowed the definition of the microbial and physicochemical changes of sausages during the shelf life (14 days). In general, the inclusion of the L2 concentration reduced the growth of several microbial targets, especially Staphylococcus spp. and LABs (2 log10 CFU/g reduction),while the increasing the growth of yeasts was observed. The reduction of microbial growth could be involved in the reduced lipolysis of raw sausages supplemented with PEOVWas highlighted by the lower amount of diacylglycerols. Moisture and aw had a significant effect on the variability of microbiological features,while food matrix (the sausages' environment) can mask the effects of PEOVW on other targets (e.g. Pseudomonas). Moreover, the molecular identification of the main representative taxa collected during the experimentation allowed the evaluation of the effects of phenols on the selection of bacteria. Genetic data suggested a possible strain selection based on storage time and the addition of phenol compounds especially on LABs and Staphylococcus spp. The modulation effects on lipolysis and the reduction of several microbial targets in a naturally contaminated product indicates that PEOVW may be useful as an ingredient in fresh sausages for improving food safety and quality

Pseudomonas and related genera

The name Pseudomonas was proposed initially by Professor W.E.F.A. Migula of the Karlsruhe Institute of Germany at the end of the 19th century (Migula, 1894, 1900; Palleroni, 2010) and it was reported for the first time in the Bergey’s Manual of Determinative Bacteriology in 1923. The choice of name seems to be due to its similarity in size and motility to the nanoflagellate Monas (from the Greek: “pseude”5false). The first description of Pseudomonas was inaccurate: Professor Migula described Pseudomonas as “. . . cells with polar organs of motility. Formation of spores occurs in some species, but it is rare. . .”. Pseudomonas pyocyanea (now P. aeruginosa) was proposed as the type species. In 1926, the extreme versatility of Pseudomonas was highlighted by L.E. den Dooren de Jong in his thesis (den Dooren de Jong, 1926; Palleroni, 2010) which focused on soil bacteria. By the middle of 1900, more than 800 species had been ascribed to Pseudomonas, creating a confusing background for researchers interested in the genus. The major cause of this erroneous classification was the trend to categorize any Gram-negative, strictly aerobic, nonsporulating, motile bacillus as a representative of the genus Pseudomonas (Scales et al., 2014). The turning point in this view was the development of first biomolecular approaches that, alongside classical microbiology, unraveled the difficult classification of the genus strains. Around the beginning of the third quarter of the 20th century, DNA/DNA hybridization revealed deep differences among phenotypically similar strains (Pecknold and Grogan, 1973). Subsequently, RNA/DNA hybridization showed the presence of 5 different rRNA groups (rRNA group I, II, III, IV, and V; Palleroni et al., 1972). Pseudomonas rRNA group I (called Pseudomonas sensu stricto) comprised P. aeruginosa, all the fluorescent Pseudomonas and some nonfluorescent Pseudomonas (such as P. stutzeri, P. alcaligenes, P. pseudoalcaligenes, and P. mendocina). A more in-depth analysis of genetic differences among Pseudomonas species was conducted with the study of 16S sequence homologies: despite the low discriminatory power of rRNA, the study allowed the identification of distinct phylogenetic groups (Laguerre et al., 1994; Anzai et al., 2000). In 2000, great advance in the study of Pseudomonas was made with a siderophore study by Meyer and colleagues that provided an excellent characterization of several species (Meyer, 2000; Meyer et al., 2002). At the present time (December 2015) the genus comprises 244 species, as reported at http://www.bacterio.net/, having different characteristics. In this chapter, the importance of the genus Pseudomonas and related genera as food spoilers is described. Taxonomic organization, identification methods, spoilage mechanisms, and control plans are reported, with the goal of highlighting the extreme complexity of the spoilage potential of the genera Pseudomonas, Xanthomonas, and Shewanella

Aeromonas

Abstract The genus Aeromonas comprises ubiquitous bacteria that are known to play several roles in the environment. They were first described as fish pathogens, but their presence has been widely documented in other reservoirs, in animals, and also in humans. To date, they are described as bona fide pathogens, but their effective role in human pathogenicity is still controversial. The focus of this article is to provide an overview of the genus mainly focussed on their role in food and health, trying to tackle the main issues that still make Aeromonas a complex genus

Food fraud and mislabeling: development of a Real-Time PCR for rapid identification of Octopus vulgaris

The consumption of seafood products, in particular cephalopods, and their worldwide commercialization is increasing in last decade. The excessive exploitation of this type of resources is going to deplete seas and oceans, moreover the most appreciated species like Octopus vulgaris are widely substituted with others ( e.g. other Octopus and Amphioctopus species). The aim of this work was the comparison among barcoding (COI) and an in-house Real-Time PCR approaches for the identification of this fraud on products sold in north east Italy. The identification method was developed through an EvaGreen Real-Time PCR, as faster and cheaper technique in comparison of the classical barcoding approach (2 day vs. 4-5 day). One hundred of samples from different FAO areas (46 Octopus vulgaris and 56 non-O. vulgaris) were applied for the experimental set-up. This method can distinguish between Octopus vulgaris and other cephalopods species through the study of the amplification curves. Sensitivity and specificity tests on all samples showed two different clusters according to the ct (cycle threshold); the 20 65 Ct 64 30 levels identified O. vulgaris samples, while a 30) need a subsequent barcoding analysis for a detailed identification of genus and species using the same DNA extracts. After the method optimization, a market survey was conducted in order to collect data about commercial fraud. Seventy-seven prepared (e.g. cooked in oil) and unprepared products from different markets of 4 provinces (north-east Italy) were analyzed with both methods. Survey data shown that 51.2% of products labeled as Octopus vulgaris were substituted with non-Octopus vulgaris species (commercial fraud), 36.2% of products declared as other octopus species are mislabeled for a total of fraud/mislabeling estimated at 44.15%. The EvaGreen Real-Time PCR showed a specificity and sensitivity of 100% and 80% respectively. Furthermore there was a substantial agreement between Real-Time PCR and barcode methods (K Cohen value = 0.86). In conclusion, this technique allowed a simple and economic method to confirm Octopus vulgaris (< 48 h ) according to the variability of the samples tested and their different provenience areas. The EvaGreen Real-Time PCR could be a routinely system in diagnostic laboratories