0000000001158563
AUTHOR
Isabella Mancuso
Anti-Listeria activity of lactic acid bacteria in two traditional Sicilian cheeses
<em>Listeria monocytogenes</em> is a pathogen frequently found in dairy products, and its growth is difficult to control. Bacteriocinlike inhibitory substances (BLIS), produced by lactic acid bacteria (LAB), having proven <em>in vitro</em> anti-<em>Listeria</em> activity, could provide an innovative approach to control <em>L. monocytogenes</em>; however, this application needs to be evaluated <em>in vivo</em>. In this study, twenty LAB strains isolated from different Sicilian dairy environments were tested for control of growth of <em>L. monocytogenes</em> in three different experimental trials. First, raw and UHT milk …
Transformation of raw ewes' milk applying “Grana” type pressed cheese technology: development of extra-hard “Gran Ovino” cheese
Abstract This work was carried out to pursue a double objective: to improve the hygienic safety of cheeses produced from raw ewes' milk; and to produce a new typology of raw ewes' milk through the application of “Grana” technology for which the name “Gran Ovino” was chosen. With this in mind, raw milk from an individual farm was transformed under controlled conditions at a dairy pilot plant. The production technology included the partial skimming of the evening and morning milk mixture by cream surfacing and the addition of a natural whey starter cultures (NWSC) prepared with four selected Streptococcus thermophilus strains (PON6, PON244, PON261 e PON413). Ten microbial groups were investig…
Characterisation of the microflora contaminating the wooden vats used for traditional Sicilian cheese production
Traditional Sicilian cheese productions are carried out employing traditional wooden vats, called <em>tina.</em> Many studies have highlighted the beneficial role of wooden dairy equipment by contributing to enriching the milk microflora and improving the acidification processes. The present work was undertaken to evaluate the safety of the wooden vats used to coagulate milk. To this purpose, the different microbial populations hosted onto the internal surfaces of the vats used to produce two different stretched cheeses, namely <em>Caciocavallo Palermitano</em> and <em>Vastedda della valle del Belìce DOP</em>, were investigated for the presence of spoilag…
Influence of the early bacterial biofilms developed on vats made with seven wood types on PDO Vastedda della valle del Belìce cheese characteristics
Early vat bacterial biofilms developed spontaneously through contact with whey have been characterized on seven wood types (Castanea sativa Miller, Cedrus libani, A. Rich., Prunus avium L., Fraxinus ornus L., Juglans regia L., Pinus nigra J.F. Arnold and Populus nigra L.). The present study aimed to evaluate the influence of these biofilms on the microbiological, chemical, physical and sensory characteristics of PDO Vastedda della valle del Belìce (VdB) cheese, processed traditionally from raw ewe's milk using wooden tools. To this purpose, the experimental cheeses after 15 d of refrigerated storage were examined. Lactic acid bacteria (LAB) populations dominated the microbial community of a…
Retrospective study on the hygienic quality of fresh ricotta cheeses produced in Sicily, Italy
The present work was carried out to investigate the microbiological profile of Sicilian ewes’ ricotta cheeses during fifteen years of investigations (2002-2016). The samples were collected between those conferred to the Istituto Zooprofilattico Sperimentale della Sicilia (IZSSi) Adelmo Mirri, Palermo (Italy), by the competent authority during official control, by food business operator in HACCP systems and in research projects. Enterobacteriaceae, Escherichia coli and coagulase-positive staphylococci (CPS) were found only in some samples. Bacillus cereus was detected in c.a. 16% of samples but the level of contaminations did not reach the threshold that leads to significant toxin production…
Microbial Activation of Wooden Vats Used for Traditional Cheese Production and Evolution of Neoformed Biofilms.
ABSTRACT Three Lactococcus lactis subsp. cremoris strains were used to develop ad hoc biofilms on the surfaces of virgin wooden vats used for cheese production. Two vats (TZ) were tested under controlled conditions (pilot plant), and two vats (TA) were tested under uncontrolled conditions (industrial plant). In each plant, one vat (TA1 and TZ1) was used for the control, traditional production of PDO Vastedda della Valle del Belìce (Vastedda) cheese, and one (TA2 and TZ2) was used for experimental production performed after lactococcal biofilm activation and the daily addition of a natural whey starter culture (NWSC). Microbiological and scanning electron microscopy analyses showed differenc…
Behavior of four main dairy pathogenic bacteria during manufacturing and ripening of pecorino siciliano cheese
Background: Consumption of raw cheese may be associated with different diseases. This study aimed to evaluate behavior of four pathogenic bacteria during manufacture and ripening of Protected Designation of Origin (PDO) Pecorino Siciliano cheese.
 Methods: The experimental cheese groups were inoculated with pathogenic bacteria, including Escherichia coli O157, Listeria monocytogenes, Salmonella Enteritidis, and Staphylococcus aureus. The cheese making processes were monitored from milk curdling until 3 months ripened cheeses and the levels of Lactic Acid Bacteria (LAB) and the four dairy pathogens were evaluated by plate counts. Randomly Amplified Polymorphic DNA (RAPD)-Polymerase Chai…
Identification and evaluation of antimicrobial resistance of enterococci isolated from raw ewes’ and cows’ milk collected in western Sicily: a preliminary investigation
The present work was carried out to investigate the Antimicrobial Resistance (AMR) of enterococci isolated from raw ewes’ and cows’ milk. The samples were collected from eighteen semi-extensive dairy sheep and cow farms throughout western Sicily. Plate counts, carried out on Rapid Enterococcus Agar commonly used to detect food enterococci, revealed a maximal enterococcal concentration of approximately 4.58 Log Colony Forming Unit (CFU)/mL. Colonies were isolated and differentiated based on genetic analysis by Randomly Amplified Polymorphic DNA (RAPD)-PCR. Thirty-eight different strains were identified. Analysis by a species-specific multiplex PCR assay grouped the strains into three Enteroc…
Animal rennets as sources of dairy lactic acid bacteria
ABSTRACT The microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB), Streptococcus thermophilus and some lactobacilli, mainly Lactobacillus crispatus and Lactobacillus reuteri , were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH …
Valutazione in vitro di bacteriocin-like inhibitory substances prodotte da batteri lattici isolati da formaggi tradizionali siciliani
I batteri lattici (LAB) sono in grado di produrre differenti sostanze antimicrobiche tra cui le batteriocine, sostanze di natura proteica che stanno riscuotendo un crescente interesse per il loro possibile impiego come bio-conservanti per controllare e contenere i microrganismi indesiderati responsabili di contaminazioni e/o deterioramento delle matrici alimentari. Gli autori descrivono i risultati di uno screening volto all’identificazione di bacteriocin-like inhibitory substances (BLIS) prodotte da LAB isolati da processi produttivi di formaggi tradizionali siciliani utilizzando due metodi di screening e valutando la natura proteica delle sostanze antimicrobiche eventualmente prodotte, me…
In vitro evaluation of bacteriocinlike inhibitory substances produced by lactic acid bacteria isolated during traditional sicilian cheese making
Bacteriocins are antimicrobial proteins produced by bacteria that inhibit with a bactericidal or bacteriostatic mode of action, the growth of other bacteria. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognized as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms; for this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances (BLIS), by …
Prickly Pear By-Product in the Feeding of Livestock Ruminants: Preliminary Investigation
Simple Summary The question of sustainability of animal nutrition has become a popular topic. The gains made by recycling safe, yet otherwise valueless, by-products and wastes from human food and fiber production (green feeds) may lessen the competition between humans and animals for crops and decrease the environmental impact of food production. In this context, prickly pear by-product, which results from Opuntia ficus-indica (L.) Mill. fruits processed for juice extraction, could be an optimum by-product to ruminant feeding. This study evaluates the nutritional characteristics and its stability during storage using potassium metabisulfite as a preservative agent. This preliminary investig…
Impact of packaging on the microbiological, physicochemical and sensory characteristics of a “pasta filata” cheese
Abstract The present study evaluated the effects of four packaging technologies (vacuum, 2 types of modified atmosphere packaging [MAP1 = 70% N2/30% CO2; MAP2 = 100% N2] and paraffin) on the microbiological, chemical, physical and volatile organic composition, and the sensory characteristics of typical Sicilian stretched raw milk PDO (Protected Destination of Origin) Vastedda della Valle del Belice (VdB) cheese. The packaging applied did not affect the microbiological profiles of the cheeses. Of the chemical and physical parameters, only pH and water activity (aw) were statistically different among the trials. In particular, the cheeses wrapped in paraffin showed the highest pH value while …
Effect of lambing season on ewe’s colostrum composition
Colostrum provides newborns with nutrients and immunoglobulins that play a major role in the immune system. In this survey, the immunoglobulin G (IgG) content, gross composition, mineral content, and fatty acid composition were determined in the colostrum of Valle del Belice ewes with the aim of evaluating the effect of lambing of season. In total, we analysed 60 bulk tank colostrum samples taken after lambing during two seasons (summer and winter). The IgG con- tent and Brix mean values were 40.35 g/L and 21.02%, respectively. The colostrum fat, protein, casein, and lactose percentages were 8.01, 12.10, 8.51, and 3.13%, respectively. The lambing sea- son significantly influenced the pH and…
Microbial diversity of traditional Sicilian cheeses
In the last years, the microbial characterisation of traditional Sicilian cheeses, such as Caciocavallo Palermitano, Protected Designation of Origin (PDO) Pecorino Siciliano and PDO Vastedda della valle del Belìce have been the object of different studies conducted by our research group. To this purpose, the aim of the present study was to describe the microbial population of traditional Sicilian cheeses.