The quality of Valle del Belice sheep’s milk and cheese produced in the hot summer season in Sicily

In response to the growing consumer demand for fresh cheese in summer, this investigation was aimed to evaluate the chemical and microbiological characteristics of sheep’s milk and cheese produced in Sicily in the hot summer months. A total of 810 bulk milk samples collected from 17 farms rearing ewes of the Valle del Belice breed were analysed for chemical composition, somatic cell count, total bacterial count and clotting parameters. Samples (n=18) of Protected Designation of Origin Vastedda della valle del Belice cheese produced in six dairies were collected in summer, autumn and spring and analysed for chemical composition, microbiological profile and fatty acid (FA) composition. Univariate and multivariate analyses were performed to assess variations by season. Sheep’s milk produced in the summer had higher fat and casein contents, less lactose and urea and slightly higher total bacterial count and, similar to milk produced in winter, had a weaker clotting ability. Vastedda cheese produced in spring had less thermophilic lactococci and a high rumenic acid content. Cheese produced in summer had more fat; less saturated FA; and more linoleic acid, monounsaturated FA and omega-3 polyunsaturated FA. A dual approach to data analysis revealed a strong influence of production season on bulk milk and Vastedda cheese characteristics due to climate conditions and ewes’ feeding regimen. Although this study provides evidence of the good nutritional properties of summer sheep’s cheese, management and feeding strategies could aim to further improve the quality of milk and cheese produced in the summer months

factors associated with milk urea concentrations in girgentana goats

A total of 1,481 milk samples of 166 Girgentana goats, taken along the entire lactation, were utilised to evaluate the effect of non nutritional factors on milk urea (MU). Parity, stage of lactation and month of sampling significantly influenced MU, while no effect was found for born kids number. The first kidding goats produced lower MU than multiparous goats. Trend of MU was similar to milk production course with a peak found at 60 DIM. The different MU levels between several months of production are often linked to pasture chemical variations

Anti-Listeria activity of lactic acid bacteria in two traditional Sicilian cheeses

Listeria monocytogenes is a pathogen frequently found in dairy products, and its growth is difficult to control. Bacteriocin-like inhibitory substances (BLIS), produced by lactic acid bacteria (LAB), having proven in vitro anti-Listeria activity, could provide an innovative approach to control L. monocytogenes; however, this application needs to be evaluated in vivo. In this study, twenty LAB strains isolated from different Sicilian dairy environments were tested for control of growth of L. monocytogenes in three different experimental trials. First, raw and UHT milk were inoculated with LAB strains alone, and LAB strains mixed with L. monocytogenes. Second, mini-cheeses containing LAB and/or L. monocytogenes were produced. Third, two traditional Sicilian cheeses inoculated with a multi-strain LAB mixture combined with L. monocytogenes were produced. The addition of BLIS produced by LAB to milk and in mini-cheese production was unable to inhibit the growth of L. monocytogenes. However, an anti-Listeria effect was observed in the Pecorino Siciliano cheeses, where, after 15 days of ripening, the cheeses with added LAB had fewer L. monocytogenes compared to the control cheeses with no added LAB, while in the Vastedda della valle del Bel\uecce cheeses, the multi-strain LAB mixture completely prevented the growth of L. monocytogenes

The influence of the wooden equipment employed for cheese manufacture on the characteristics of a traditional stretched cheese during ripening

The influence of the wooden equipment used for the traditional cheese manufacturing from raw milk was evaluated on the variations of chemico-physical characteristics and microbial populations during the ripening of Caciocavallo Palermitano cheese. Milk from two farms (A, extensive; B, intensive) was processed in traditional and standard conditions. Chemical and physical traits of cheeses were affected by the farming system and the cheese making technology, and changed during ripening. Content in NaCl and N soluble was lower, and paste consistency higher in cheese from the extensive farm and traditional technology, whereas ripening increased the N soluble and the paste yellow and consistency. The ripening time decreased the number of all lactic acid bacteria (LAB) groups, except enterococci detected at approximately constant levels (104 and 105 cfu g-1 for standard and traditional cheeses, respectively), till 120 d of ripening. In all productions, at each ripening time, the levels detected for enterococci were lower than those for the other LAB groups. The canonical discriminant analysis of chemical, physical and microbiological data was able to separate cheeses from different productions and ripening time. The dominant LAB were isolated, phenotypically characterised and grouped, genetically differentiated at strain level and identified. Ten species of LAB were found and the strains detected at the highest levels were Pediococcus acidilactici and Lactobacillus casei. Ten strains, mainly belonging to Lactobacillus rhamnosus and Lactobacillus fermentum showed an antibacterial activity. The comparison of the polymorphic profiles of the LAB strains isolated from the wooden vat with those of the strains collected during maturation, showed the persistence of three enterococci in traditional cheeses, with E. faecalis found at dominant levels over the Enterococcus population till 120 d; the absence of these strains in the standard productions evidenced the contribution of vat LAB during Caciocavallo Palermitano cheese ripening

Studio retrospettivo sulla qualit\ue0 igienico-sanitaria delle ricotte prodotte in Sicilia

La ricotta \ue8 un prodotto lattiero caseario estremamente diffuso nei paesi del Mediterraneo ottenuto per termocoagulazione acida del siero. Scopo del lavoro \ue8 stato valutare la qualit\ue0 igienico sanitaria delle ricotte siciliane mediante uno studio retrospettivo; sono stati analizzati i dati dei campioni conferiti all\u2019ZS della Sicilia per controllo ufficiale, autocontrollo o progetti di ricerca. Dal 2002 ad oggi sono state esaminate 1295 ricotte fresche, nella maggior parte dei campioni sono stati ricercati L. monocytogenes (1156), Salmonella sp. (998), Brucella sp. (721), Stafilococchi coagulasi positivi (639) e E. coli (598). Su un numero di campioni variabile fra 98 e 371 \ue8 stata eseguita la determinazione della CBT, la numerazione di B. cereus, Pseudomonas sp., spore di anaerobi, lieviti e muffe, enterococchi, flora lattica e determinazione del pH. Le analisi sono state effettuate con metodi normati o con metodi interni validati, alcuni batteri lattici isolati sono stati genotipizzati mediante analisi della sequenza del gene 16S rDNA. Nessun campione \ue8 risultato positivo a L. monocytogenes, Salmonella sp. e Brucella sp. Nel 16% dei campioni era presente B. cereus in concentrazioni fra 1 e 6 log ufc/g; nel 21% erano presenti Enterobacteriaceae (1-7 log), nel 13% E. coli (1-4 log) e nel 14% lieviti e muffe (1-3 log). Nel 2% dei campioni sono stati ritrovati Pseudomonas sp. (2 log) e Stafilococchi coagulasi positivi (1-5 log). I valori di CBT erano compresi fra 2 e 8 log ufc/g (valore medio 5.12\ub11.64), gli enterococchi (1-6 log, valore medio 3.62\ub11.24) e flora lattica fra 1 e 7 log ufc/g. Le ricotte presentavano valori medi di pH pari a 6,39. La maggior parte dei batteri lattici apparteneva alle specie Lactococcus lactis e Lactobacillus casei. I risultati ottenuti evidenziano una buona qualit\ue0 delle ricotte siciliane per l\u2019assenza dei patogeni; la presenza di microrganismi indicatori di igiene evidenzia la necessit\ue0 di migliorare le condizione igieniche di produzione considerato che la ricotta, per le sue caratteristiche chimico-fisiche, rappresenta un buon substrato per lo sviluppo di microrganismi (Fadda et al., 2012)

Prickly pear by-product in the feeding of livestock ruminants: Preliminary investigation

In Sicily, the current increasing cultivation of Opuntia ficus-indica corresponds to an availability of prickly pear by-product (PPB) that results from fruit processing for juice extraction. This investigation aims to evaluate the nutritional traits of PPB for ruminant feeding and its stability during a 21-day outdoor storage, using potassium metabisulfite (PMB) as a preservative agent, added to the PPB mass at different doses (0, 50, 100, and 150 g/kg). The fractioning of PPB showed that it included 28% of peel and pulp and 72% of seeds on a dry matter (DM) basis. On the whole, this by-product was low in crude protein (5.32% DM), high in fiber content (51.38%, 41.15% and 14.64% DM for NDFom, ADFom and ADL respectively), non-fiber carbohydrates (NFC, 29.68% DM), and soluble sugars (13.3% DM), with a moderate level of net energy for lactation (4.59 MJ/kg DM). Storage was the main factor of alteration of PPB chemical composition with the exception of ether extract. A decline of NFC and soluble sugars, due to microbial fermentation, was observed with all PMB treatments, especially during the first week of storage, probably due to evolution of both coccus (M17) and rod LAB (MRS), which increased their loads at the seventh day of storage

In vivo application and dynamics of lactic acid bacteria for the four-season production of Vastedda-like cheese.

Twelve lactic acid bacteria (LAB), previously selected in vitro (Gaglio et al., 2014), were evaluated in situ for their potential to act as starter cultures for the continuous four-season production of Vastedda-like cheese, madewith raw ewes' milk. The strains belonged to Lactobacillus delbrueckii, Lactococcus lactis subsp. cremoris, Leuconostoc mesenteroides subsp. mesenteroides and Streptococcus thermophilus. LABwere first inoculated in multiple-strain combinations on the basis of their optimal growth temperatures in three process conditions which differed for milk treatment and medium for strain development: process 1, growth of strains in the optimal synthetic media and pasteurised milk; process 2, growth of strains in whey based medium (WBM) and pasteurised milk; and process 3, growth of strains in WBM and raw milk. The strains that acidified the curds in short time, as shown by a pH drop, were all mesophilic and were then tested in a single inoculum through process 3. Randomly amplified polymorphic DNA (RAPD)-PCR analysis applied to the colonies isolated from the highest dilutions of samples confirmed the dominance of the added strains after curd acidification, stretching and storage. After 15 days of refrigerated storage, the decrease in pH values showed an activity of the mesophilic strains at low temperatures, but only Lc. lactis subsp. cremoris PON153, Ln. mesenteroides subsp. mesenteroides PON259 and PON559 increased their number during the 15 days at 7 \ub0C. A sensory evaluation indicated that the cheeses obtained by applying protocol 3 and by inoculation with lactococci are the most similar to the protected denomination of origin (PDO) cheese and received the best scores by the judges. Thus, the experimental cheeses obtained with raw milk and inoculated with single and multiple combinations of lactococci were subjected to the analysis of the volatile organic compounds (VOCs) carried out by a headspace solid phase microextraction (SPME) technique coupled with gas chromatography with mass spectrometric detection (GC/MS). The dominance of lactococci over thermophilic LAB of raw milk was verified during summer production and, based on the combination of VOC profiles and sensory evaluation of the final cheeses, the multi-strain Lactococcus culture resulted in the most suitable starter preparation for the full-year production of Vastedda-like cheese

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 tina. 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 Caciocavallo Palermitano and Vastedda della valle del Bel\uecce DOP, were investigated for the presence of spoilage and pathogenic microorganisms as well as for bacteria with inhibitory effect in vitro against pathogenic microorganisms. A wide biodiversity of protechnological lactic acid bacteria (LAB), in terms of species, was revealed. Several LAB inhibited the growth of Listeria monocytogenes ATCC 7644. The wooden vats analysed resulted safe for three main findings: absence of the main pathogenic species, presence of high levels of LAB, anti-Listeria activity of many LAB

A First Investigation into the Use of Differential Somatic Cell Count as a Predictor of Udder Health in Sheep

Differential somatic cell count (DSCC), the percentage of somatic cell count (SCC) due to polymorphonuclear leukocytes (PMNs) and lymphocytes (LYMs), is a promising effective diagnostic marker for dairy animals with infected mammary glands. Well-explored in dairy cows, DSCC is also potentially valid in sheep, where clinical and subclinical mastitis outbreaks are among the principal causes of culling. We pioneered the application of DSCC in dairy ewes by applying receiver-operating characteristic (ROC) curve analysis to define the most accurate thresholds to facilitate early discrimination of sheep with potential intramammary infection (IMI) from healthy animals. We tested four predefined SCC cut-offs established in previous research. Specifically, we applied SCC cut-offs of 265 × 103 cells/mL, 500 × 103 cells/mL, 645 × 103 cells/mL, and 1000 × 103 cells/mL. The performance of DSCC as a diagnostic test was assessed by examining sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), and area under curve (AUC) analyses. The designated threshold value for DSCC in the detection of subclinical mastitis is established at 79.8%. This threshold exhibits Se and Sp of 0.84 and 0.81, accompanied by an AUC of 0.88. This study represents the inaugural exploration of the potential use of DSCC in sheep’s milk as an early indicator of udder inflammation