1,721,020 research outputs found
Development of infrared prediction models for diffusible and micellar minerals in bovine milk
Full text linkMilk and dairy products are major sources of minerals in human diet. Minerals influence milk technological properties; in particular, micellar and diffusible minerals differentially influence rennet clotting time, curd firmness and curd formation rate. The aim of the present study was to investigate the ability of mid-infrared spectroscopy to predict the content of micellar and diffusible mineral fractions in bovine milk. Spectra of reference milk samples (n = 93) were collected using MilkoscanTM 7 (Foss Electric A/S, Hillerød, Denmark) and total, diffusible and micellar content of minerals were quantified using inductively coupled plasma optical emission spectrometry. Backward interval partial least squares algorithm was applied to exclude uninformative spectral regions and build prediction models for total, diffusible and micellar minerals content. Results showed that backward interval partial least squares analysis improved the predictive ability of the models for the studied traits compared with traditional partial least squares approach. Overall, the predictive ability of mid-infrared prediction models was moderate to low, with a ratio of performance to deviation in cross-validation that ranged from 1.15 for micellar K to 2.73 for total P
Characterizing the fecal bacteria and archaea community of heifers and lactating cows through 16S rRNA next-generation sequencing
Full text linkThe aim of this study was to describe the fecal bacteria and archaea composition of Holstein-Friesian and Simmental heifers and lactating cows, using 16S rRNA gene sequencing. Bacteria and archaea communities were characterized and compared between heifers and cows of the same breed. Two breeds from different farms were considered, just to speculate about the conservation of the microbiome differences between cows and heifers that undergo different management conditions. The two breeds were from two different herds. Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria were the most abundant phyla in all experimental groups. Alpha- and beta-diversity metrics showed significant differences between heifers and cows within the same breed, supported by principal coordinate analysis. The analysis of Holstein-Friesian fecal microbiome composition revealed 3 different bacteria families, 2 genera, and 2 species that differed between heifers and cows; on the other hand, Simmental heifers and cows differed only for one bacteria family, one archaeal genus, and one bacteria species. Results of the present study suggest that fecal communities of heifers and cows are different, and that fecal microbiome is maintained across experimental groups
Variation of lactoferrin and whey protein fractions along different stages of milk technological processing at dairy plant level
Full text linkThis study assessed the concentration of whey protein fractions in different dairy matrices, including raw milk (RM), pasteurized milk (PM), cheese whey (CW), and Ricotta cheese whey (RW) collected along the production of mozzarella and Asiago cheeses. A linear mixed model was implemented in order to analyze the variability of bovine serum albumin (BSA), lactoferrin (LF), α-Lactalbumin (α-LA), β-lactoglobulin A (β-LG A) and B (β-LG B). Results suggest that analyzed dairy matrices are characterized by specific whey protein profiles. Lactoferrin and α-LA concentrations linearly decreased due to technological processing stages, while BSA, β-LG A and β-LG B declined mainly in RW (i.e. after Ricotta production). In terms of relative abundance, LF was least abundant in RM, PM, and CW but most prominent in RW. Despite challenges posed by pasteurization and cheese making, CW remained a substantial source of LF and whey proteins, offering potential for economical and nutritional applications
Mineral equilibrium in commercial curd and predictive ability of near-infrared spectroscopy
Full text linkCurd samples (n = 83) from 3 European dairy companies were analyzed for micellar and soluble mineral fractions content using inductively coupled plasma optical emission spectrometry as a gold standard method. The same curd samples were analyzed through 3 different near-infrared (NIR) instruments, and NIR spectra were merged with reference data. Prediction equations were developed using modified partial least squares analysis, and the accuracy of prediction was evaluated through leave-one-out cross validation. Overall, NIR spectroscopy was capable of predicting micellar and soluble mineral fractions in curd, but with differences among instruments. Fitting statistics showed that the visible NIR instrument in reflectance mode outperformed the NIR instrument in transmittance mode as well as the portable NIR instrument in reflectance mode. Prediction accuracies for most of the analyzed mineral fractions can be used for curd quality control in dairy companies and to aid in decision-making during the cheesemaking process
Study on molecular determinants for colistin resistance in Avian Pathogenic Escherichia coli (APEC) from commercial poultry in Italy.
No full textSince its recent discovery in November 2015, the mcr-1 gene has been detected in a variety of Enterobacteriaceae from humans, animals and the environment. In Italy, only a few reports describing the presence of mcr-1 gene in pathogenic and commensal Escherichia coli isolates from humans and poultry have been published to date. Mcr-1 is a plasmid-borne gene encoding for the phosphoethanolamine transferase conferring resistance to colistin, which is considered a life-saving antibiotic for humans. In poultry, colistin is widely used for treating or preventing bacterial infections. The aim of this study was to estimate the presence of the mcr-1 gene in Avian Pathogenic Escherichia coli (APEC) isolated from intensive poultry farms.
The screening was carried out on a collection of non-repetitive APEC isolated from organs and tissues collected from commercial poultry, showing lesions suggestive of colibacillosis. A total of 229 APEC strains, collected between 2008 and 2012, were screened to detect the presence of the mcr-1 gene. In detail, strains were isolated from turkeys (n=109), broilers (n=98), and layer hens (n=22). To detect the presence of the mcr-1 gene, a PCR to amplify an internal fragment of 308 bp was performed. Afterwards, the whole mcr-1 gene was sequenced using a different set of primers amplifying a fragment of 1,600 bp. PCR protocols were carried out according to the publication of Liu and colleagues (2016). Finally, strains with a confirmed presence of the mcr-1 gene were analysed by Minimum Inhibitory Concentration (MIC), according to the European Committee on Antimicrobial Susceptibility Testing guidelines (EUCAST, 2016).
Out of 229 strains, 29 (12,6%) were positive to the mcr-1 gene. Sequence analysis of all strains showed a sequence identity of 100% compared to the original sequence (NCBI accession number: NG_050417). Most strains (n = 20) had MIC values of ≥ 2 mg/L, which is the epidemiological cut-off value (ECOFF) for colistin, according to EUCAST. The remaining strains (n=9) had MIC values of < 2 mg/L, which correspond to the wild type phenotype.
Until now, most of the studies investigating on the dissemination of mcr-1 gene in poultry or its products have been carried out on commensal E. coli, even in Italy. In this study, we focused on the occurrence of colistin resistance in APEC strains, which can cause infections with serious economic consequences for the poultry industry. Our results demonstrate a high prevalence of the mcr-1 gene in the studied APEC population. Interestingly, the MIC values of some of the analysed mcr-1 carrying isolates are consistent with intermediate resistance or even susceptibility to colistin. Of note, this phenomenon might lead to a silent dissemination of the mcr-1 gene among bacterial populations with unknown implications. Even more, this finding suggests that colistin resistance assessed only by phenotypic susceptibility assays could be misleading when determining the prevalence of the mcr-1 gene. Further investigation is crucial because colistin is an essential antimicrobial drug for the poultry sector as well as for public health. We are currently investigating also on the presence of the mcr-2 gene in order to obtain a full spectrum of the plasmid-borne resistance determinants for colistin in APEC isolates
Effects of preservative, storage time, and temperature of analysis on detailed milk protein composition determined by reversed-phase high-performance liquid chromatography
Full text linkMilk preservative and freezing are used as strategies to prevent microbial growth and milk degradation, especially when immediate analytical processing is not feasible. The effects of the addition of preservative and freezing procedures have been investigated mainly in relation to milk gross chemical composition predicted through mid-infrared spectroscopy. This study aimed to determine whether different preservatives (i.e., no preservative, hydrogen peroxide, Bronopol, and Azidiol), freezing times (i.e., 0, 7, and 30 d), and temperatures of analysis (i.e., 5 and 21°C) influence the composition of milk protein fractions determined through reversed-phase HPLC. Bulk milk samples for the analysis of protein profile were collected from 5 commercial dairy farms. Data were analyzed with a linear mixed model, which included type of preservative, time of storage, temperature of analysis, and the interaction between type of preservative and time of storage as fixed effects, with the farm and the residual as random effects. Samples with no preservative had the greatest amount of all protein fractions, whereas Bronopol-preserved milk had the lowest amount. Increasing storage time under freezing conditions had a nonlinear detrimental effect on milk protein fractions. The temperature of analysis significantly contributed to the variation of κ-casein, β-casein, αS1-casein, β-lactoglobulin, and α-lactalbumin fractions. The z-scores were calculated to evaluate the similarity between detailed protein profile of fresh milk without preservative analyzed at 5°C and detailed protein profile of milk treated according to the tested conditions. Overall results suggested a good agreement between different analytical conditions. Still, short storage time under freezing conditions is recommended to avoid degradation of milk protein fractions and consequent analytical underestimation
Effectiveness of energy-dispersive X-ray fluorescence for the quantification of mineral elements in skim milk and whey powders
Full text linkMilk and whey are subjected to quick deterioration due to bacterial growth. Turning them into powder allows for extended shelf life, easier storage, and more effective transport. Monitoring mineral elements in dairy powders is crucial for both technological and nutritional implications. Current analysis of minerals in food matrixes is time consuming and requires high costs and labor. Energy-dispersive X-ray fluorescence (ED-XRF) may represent a potential alternative technique to rapidly determine mineral content of food matrixes. The present study aimed to investigate the effectiveness of the EDXRF technique for the prediction of Na, Mg, P, S, K, Ca, Cu, and Zn in skim milk and whey powders. Reference analysis for mineral concentration in dairy powders was inductively coupled plasma-optical emission spectrometry. The accuracy of ED-XRF for the prediction of mineral elements was assessed on all available samples (global calibration set; n = 23) and after splitting the whole data into a training set (n = 16) and a testing set (n = 7), comprising 70% and 30% of the available samples, respectively. The accuracy of prediction was moderate to low for Na and Mg, whereas robust predictions were obtained for P, S, K, Ca, Cu, and Zn, with coefficients of determination in global calibration from 0.88 to 0.99, and ratios performance to deviation in testing from 2.14 to 24.74. Results suggest that ED-XRF can be considered for accurate prediction of the main mineral elements in dairy powders
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Assessment of energy dispersive X-ray fluorescence (ED-XRF) for quantification of iodine in non-lyophilized milk
Full text linkIodine represents a fundamental element for human health, with particular regard to thyroid function. Dietary intake of milk naturally rich in iodine becomes of primary importance in the prevention of syndromes related to iodine deficiency. The concentration of iodine in milk is characterized by wide variability, mainly related to animal feed and level of mineral supplementation. Therefore, there is interest in the development of fast analytical techniques which are able to predict milk iodine concentration. The aim of the present study was to investigate the effectiveness of energy-dispersive X-ray fluorescence (ED-XRF) for the prediction of iodine in cow milk. Results showed moderate accuracy of the ED-XRF technique, with a coefficient of determination in cross validation of 0.60. This study represents a first contribution towards the possibility to discriminate milk with high or low iodine concentration, as an essential preliminary step for the introduction into the market of naturally fortified milk
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