164 research outputs found
Topology in full QCD at high temperature: a multicanonical approach
We investigate the topological properties of QCD with physical
quark masses, at temperatures around 500 MeV. With the aim of obtaining a
reliable sampling of topological modes in a regime where the fluctuations of
the topological charge are very rare, we adopt a multicanonical approach,
adding a bias potential to the action which enhances the probability of
suppressed topological sectors. This method permits to gain up to three orders
of magnitude in computational power in the explored temperature regime. Results
at different lattice spacings and physical spatial volumes reveal no
significant finite size effects and the presence, instead, of large finite
cut-off effects, with the topological susceptibility which decreases by 3-4
orders of magnitude while moving from fm towards the continuum
limit. The continuum extrapolation is in agreeement with previous lattice
determinations with smaller uncertainties but obtained based on ansatzes
justified by several theoretical assumptions. The parameter , related to
the fourth order coefficient in the Taylor expansion of the free energy density
, has instead a smooth continuum extrapolation which is in agreement
with the dilute instanton gas approximation (DIGA); moreover, a direct
measurement of the relative weights of the different topological sectors gives
an even stronger support to the validity of DIGA.Comment: 23 pages, 13 figure
Analysis of microbiological variation in PDO Vastedda della valle del BelĂŹce cheese during the storage period
The PDO âVastedda della valle del BelĂŹceâ is a Sicilian pasta filata sheep cheese, made from raw milk without starter addition. It is a small round cheese without rind, weighing about 500-700 g. It is cheese is marketed also out of Sicily to allow its marketing and to prolong its shelf-life.
The aim of this work was to evaluate the variation of microbiological parameters during the shelf-life period. Then 162 Vastedda cheeses from 18 cheese-making processes in 7 farms have been analysed at different times of storage at 4°C (0, 15, 30, 45, 60, 75, 90, 105, 120 days).
Coliforms and E. coli were detected into 7/18 cheese-making processes and their count decreased during the storage period. Enterococci were more resistant to high temperature achieved during the stretching and their were rather stable during storage period (105 cfu/g).
The concentration of total Bacterial Count and Mesophilic Lactococci were around 107 cfu/g, while the concentration of Thermophilic Lactococci was higher (108 cfu/g) probably due to the stretching at 90°C.
In conclusion, this study shows the good sanitary conditions of cheeses. Overall, the lactic flora was kept alive and vital at high concentration (> 107 cfu/g) until 120 days of storage
Multivariate factor analysis of Girgentana goat milk composition
The interpretation of the several variables that contribute to defining milk quality is difficult due to the high degree of correlation among them. In this case, one of the best methods of statistical processing is factor analysis, which belongs to the multivariate groups; for our study this particular statistical approach was employed.
A total of 1485 individual goat milk samples from 117 Girgentana goats, were collected fortnightly from January to July, and analysed for physical and chemical composition, and clotting properties. Milk pH and tritable acidity were within the normal range for fresh goat milk. Morning milk yield resulted 704 ± 323 g with 3.93 ± 1.23% and 3.48±0.38% for fat and protein percentages, respectively. The milk urea content was 43.70 ± 8.28 mg/dl. The clotting ability of Girgentana milk was quite good, with a renneting time equal to 16.96 ± 3.08 minutes, a rate of curd formation of 2.01 ± 1.63 minutes and a curd firmness of 25.08 ± 7.67 millimetres.
Factor analysis was performed by applying axis orthogonal rotation (rotation type VARIMAX); the analysis grouped the milk components into three latent or common factors. The first, which explained 51.2% of the total covariance, was defined as âslow milksâ, because it was linked to r and pH. The second latent factor, which explained 36.2% of the total covariance, was defined as âmilk yieldâ, because it is positively correlated to the morning milk yield and to the urea content, whilst negatively correlated to the fat percentage. The third latent factor, which explained 12.6% of the total covariance, was defined as âcurd firmness,â because it is linked to protein percentage, a30 and titatrable acidity. With the aim of evaluating the influence of environmental effects (stage of kidding, parity and type of kidding), factor scores were analysed with the mixed linear model. Results showed significant effects of the season of kidding and parity on common factors, while no differences were found between goats with one or more kids. The multivariate factor analysis technique was effective in describing the quality of Girgentana milk with a low number of new latent variables. These new variables have been useful in the study of the effect of some technical factors such as parity and season of kidding on the quantitative and qualitative aspects of milk production in this goat breed
The quality of Valle del Belice sheepâs 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 sheepâs 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. Sheepâs 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 ewesâ feeding regimen. Although
this study provides evidence of the good nutritional properties of summer sheepâs
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
Chemometric Approaches to Analyse the Composition of a Eweâs Colostrum
Colostrum is a major source of immunity in lambs and, in general, in all newborn ruminants. It allows the transfer of antibodies from the ewe to the lamb, and it becomes the exclusive source of nutrients for a newborn. Among the most significant Pearson correlations, the positive correlation between the Brix refractive index (Brix) and protein (0.90) should be noted. Both parameters (protein percentage and Brix) were then positively correlated with the percentage of fat (0.38 and 0.41), urea (0.81 and 0.67), calcium (0.39 and 0.29), and magnesium (0.58 and 0.59), as well as the yellowness (0.78 and 0.75). Somatic cell count (SCC) and pH, parameters which are indicators of subclinical mastitis, were positively correlated (0.49), and SCC was positively correlated with sodium (0.37) and negatively correlated with potassium (â0.28). Among the macroelements in colostrumâcalcium, potassium, magnesium, and sodiumâthe correlations were largely positive. With respect to the colour parameters, yellowness was negatively correlated with lightness (â0.41) and redness (â0.45). The factor analysis split the total of variance into three latent factors. The first factor was named âColostrum quality of grazing sheepâ because it was positively correlated primarily with SCC, pH, Poly Unsatured Fatty Acids (PUFA), and the sum of the omega-3 Fatty Acids (FAs). The second factor, named âGood quality colostrumâ, was positively correlated primarily with the refractive index, protein and fat percentages, urea content, phosphorus, Mono Unsatured Fatty Acids (MUFA), and yellowness. The third factor was positively correlated primarily with calcium, potassium, magnesium, and sodium, and it was therefore termed âMineral component of colostrumâ. Stepwise discriminant analysis showed that the protein percentage, calcium, and magnesium were able to explain more than 85% of the Brix refractive index, which remains a good parameter for simply evaluating the nutritional quality of sheep colostrum at the level of a farm
Growth performance in heavy lambs experimentally treated with 17 ÎČ-estradiol
European and Italian legislation have banned use
of growth promoters in livestock since 1988, but epidemiological
data show that anabolic drugs are still being used
illegally. Recent surveys carried out on the cattle farms in
Northern Italy have confirmed the presence of growthpromoting
hormones. Authors report data on growth performances
in 80 Valle del BeliceĂComisana weaned lambs
experimentally treated with 17 beta-estradiol with 0.5 ml
solution of oil Depot Estradiol Âź (containing 5 mg of 17ÎČ-
estradiol valerate) by intramuscular injection into the thigh.
The experiment was founded by the National Ministry of
Health, to validate histological test for surveillance and
control of growth-promoting hormones in sheep. This study
confirmed the strong correlation between clinical and anatomopathological
features and growth performances of treated
animals. Otherwise, no significant differences were found on in vivo performance of the lambs. Estradiol treatment
showed heavier shoulders and necks on treated lambs,
while the loins were significantly lighter. Moreover, lambestradiol-
treated groups showed lower separable and inseparable
fat percentage than lamb-control groups
Effect of different salting technologies on the chemical and microbiological characteristics of PDO Pecorino Siciliano cheese
The present work was carried out to evaluate
the effect of two salting technologies [dry salting (DS) and
the combined dry-brine salting (DBS)] on the chemicophysical
and microbiological characteristics of PDO Pecorino
Siciliano cheeses of different final weight (6 and
12 kg). Dry matter was significantly influenced by both
salting process and final size. Twelve kilogram cheeses
treated by DBS showed higher protein content with higher
soluble nitrogen per cent than 6 kg cheeses. Salt content
was in the range 3.1â4.0% on dry matter. The colour did
not show significant differences for any of the factors, but
12 kg cheeses subjected to DS showed higher yellow index
than the other cheeses. The resistance at 30% of strain was
influenced by cheese size, with 6 kg cheeses showing
higher resistances than 12 kg cheeses. All cheeses were
dominated by coccus LAB, but pseudomonads and Enterobacteriaceae
showed comparable levels of about 105 cfu/g.
Significant microbiological differences were evidenced
only for enterococci and yeasts concerning the final cheese
size. Thirteen species of LAB, belonging to five genera
(Enterococcus, Lactobacillus, Lactococcus, Pediococcus
and Streptococcus), were identified, but several spoilage/
pathogenic species were also identified, especially Pseudomonas
putida, Citrobacter freundii and Stenotrophomonas
maltophilia. LAB isolates were preliminary
evaluated for their physiological characteristics in view of developing autochthonous starters to improve the microbiological
quality of PDO Pecorino Siciliano cheese
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