1,721,053 research outputs found
Il progetto EULAT : sostenibilità ambientale e benessere animale negli allevamenti lombardi di bovine da latte
No full textRelazione tra la pulizia delle bovine e la qualità igienica e sanitaria del latte
No full textRelationship between cow hygiene and somatic cell and bacterial
counts in bulk tank milk. – The quality of bulk tank milk, in term of bacterial
contamination and proliferation, is influenced by milking machine and milk
tank cleaning, by animal hygiene and by the presence of mastistis microrganisms
into the udder. The aim of the present work was to evaluate cow hygiene
(Hygiene Score, HS) and its effects on Somatic Cell Count (SCC) and bacterial
count (SBC) in the bulk tank milk. Udder, flank and legs HS were evaluated in
10 farms, each farm were visited twice. SBC, thermoduric and coliform bacteria
were evaluated on bulk tank milk (ISO/FIL 4833 and ISO/FIL 4831), SCC were
obtained from AIA (Italian Breeders Association) database. Farms with less
than 100 cows were characterized by 4.81; 2.44 and 3.05 log10 CFU/mL respectively
of SPC, thermoduric and coli bacteria, whereas farms with more than 100
cows had 4.74 log10 CFU/mL of SPC; 2.70 log10 CFU/mL of thermoduric and
2.58 CFU/mL of coli. SSC expressed as Linear Score (LS) was 5.36 e 5.51 respectively
in two groups of farms. All farms were quite clean, only 18% of the udder
were classified as dirty (HS 3 and 4). Farm visits with less than 10% udder HS
3 and 4, less than 35% of flanks and 40% of legs HS 3 and 4, were characterized
by better milk quality than “dirty visits” (CBS = 5.1 vs 5.4 log10 CFU/mL; ther-
Bava et al (2008) Sci Tecn Latt-Cas, 59 (4), 000-000 178
moduric = 3.2 vs 3.1 log10 CFU/mL e coli = 2.8 vs 3.5 log10 CFU/mL, for clean and
dirty visits respectively)
Changes in oxidation-reduction potential during milk fermentation by wild lactic acid bacteria
No full textOxidation-reduction potential (E h) is a fundamental physicochemical property of lactic acid bacteria that determines the microenvironment during the cheese manufacture and ripening. For this reason the E h is of growing interest in dairy research and the dairy industry. The objective of the study was to perform a comprehensive study on the reduction activity of wild lactic acid bacteria strains collected in different periods (from 1960 to 2012) from Italian dairy products. A total of 709 strains belonging to Lactococcus lactis, Enterococcus durans, E. faecium, E. faecalis and Streptococcus thermophilus species were studied for their reduction activity in milk. Kinetics of milk reduction were characterised by the minimum redox potential (Eh7) and time of reaching Eh7 (tmin), the maximum difference between two measures (Δmax) and the time at which these maximum differences occurred (t∗). Broad diversity in kinetic parameters was observed at both species and strain levels. E. faecalis and L. lactis resulted to be the most reducing species, while S. thermophilus was characterised by the lowest reducing power while the greatest heterogeneity was pointed out among E. durans and E. faecium strains. Considering the period of collection (1960-2012) we observed that the more recently isolated strains generally showed less reducing activity. This trend was particularly evident for the species E. durans, E. faecium and L. lactis while an opposite trend was observed in E. faecalis species. Data reported in this research provide new information for a deeper understanding of redox potential changes during milk fermentation due to bacterial growth. Gain knowledge of the redox potential of the LAB cultures could allow a better control and standardisation of cheesemaking process
Redox potential to discriminate among species of lactic acid bacteria
No full textAIMS: To verify to what degree reducing capacity is a characterizing parameter of a species, and of the strains themselves within a given species, of lactic acid bacteria.
METHODS AND RESULTS: Eighty-eight strains belonging to 10 species of lactic acid bacteria (LAB) isolated from traditional Italian cheeses were studied for their reduction activity: Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, Streptococcus thermophilus, Lactococcus lactis ssp. lactis, Lactobacillus paracasei ssp. paracasei, Lactobacillus plantarum, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus helveticus and Pediococcus pentosaceus. It was observed that the lactococci reached minimum redox potential before the lactobacilli. The reduction rate of Enterococcus spp. and L. lactis ssp. lactis was higher than that of the streptococci and Lactobacillus spp. All the P. pentosaceus strains had poor reduction activity compared with the other species.
CONCLUSIONS: The evolution of the redox potential in milk over a time span of 24 h has been found to be a parameter that characterizes a species: the different courses corresponding to the species in question are clearly evident, and interesting differences can also be noted within the same species.
SIGNIFICANCE AND IMPACT OF THE STUDY: The reduction aptitude of strains might be used to select and adapt appropriate strains for use as starters for dairy products
Impiego della tecnica di bioluminescenza nello studio della crescita e fermentazione di Saccharomyces cerevisiae
No full textE’ stata studiata l’evoluzione della crescita microbica in un processo fermentativo mediante la tecnica della bioluminescenza che permette di dosare il contenuto di ATP cellulare. I risultati sono stati confrontati con quelli ottenuti utilizzando i metodi della microbiologia classica (conta in piastra cellule vitali, dosaggio del substrato consumato e dei prodotti del metabolismo). E’ stato così possibile osservare l’inadeguatezza della bioluminescenza nello studio di questo processo fermentativo. Essa infatti misurando sempre tutta l’ATP presente in un sistema, non permette di acquisire informazioni circa lo stato in cui si trovano le cellule. In una fermentazione, come in molti processi biotecnologici invece, quello che maggiormente interessa è conoscere la fase di crescita delle cellule, corrispondente alla loro massima attività al fine di poter ottimizzare l’intero processoThe behavior of microbial growth in a fermentative process was investigated by means of bioluminescenza technique which allows the estimation of ATP in microbial cells. The date were compared with classical methods, which were used to value both the biomass growth (viable cell count) and the utilization of the substrate (consumption of glucose and production of ethanol). The results obtained show the inadequacy of the luminescence as a method to study the fermentative process. The technique in fact doesn’t give any information about the metabolic phase of the microbial cells, because it measure all the ATP present, without any differentiation. During fermentation, as in many other biotechnological process, the most important matter is to know the microbial growth phase corresponding to their maximum activity
Azioni per il controllo della carica batterica del latte alla stalla : Il progetto LATTESAN
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