1,720,968 research outputs found
Use of microparticulated whey protein (MWP) in the Italian dairy industry
Full text linkThe thesis is composed of four contributes, dealing with different approaches developed to understand the different aspects of whey proteins (WP) recovery, and their use across cheese manufacturing. The general aim of the research project was to investigate and propose strategies for the utilization of whey and whey products in cheese produced by an Italian dairy industry. The Soligo dairy cooperative (Soligo, Treviso, Italy) was partner and supported the project.
In this scenario, the objectives of the first contributes was to develop a gold-method for WP quantification in whey, by Reversed Phase -HPLC, and to evaluate the potential of mid infrared spectroscopy (MIRS) in WP prediction. Whey proteins included α-Lactoalbumin (α-LA), β-Lactoglobulin A and B (β-LG), bovine serum albumin, caseinomacropeptides, proteose peptone and total WP identified. Repeatability and reproducibility tests, in validation procedures, were performing by calculating the relative standard deviation (RSD) within and across days for retention times and peak areas. Samples of whey (n = 187) were analysed according to the reference methods and MIRS spectra were stored (900 - 4000 cm-1); statistical analysis was carried out through partial least squares regression and random cross-validation procedure. Retention times were stable, with RSD ranging between 0.03% and 0.80%. The RSD of peak area in repeatability and reproducibility tests ranged from 0.25% to 8.48% depending on the considered proteins and their relative abundance; indeed, better coefficients of determination in validation were obtained for fractions present in whey in large amounts, as β-LG (0.58), total identified WP (0.58), α-LA (0.56), while minor WP were predicted with minor appreciable accuracy. Results from this study propose a high-throughput and high-resolution method for WP quantification in whey and show the potential of MIRS for their prediction.
The objective of the second contribute was to investigate the effect of increasing concentrations of microparticulated whey proteins (MWP; from 0.0 to 9.0%, vol/vol) on milk coagulation properties (MCP), namely rennet coagulation time (RCT), curd-firming time, and curd firmness 30 min after rennet addition (a30). Three bulk milk samples, collected and analyzed during 3 days, were added with 6 concentrations of MWP (vol/vol): 1.5%, 3.0%, 4.5%, 6.0%, 7.5%, and 9.0%. Moreover, a sample without MWP was used as control. Milk coagulation properties were measured using Formagraph (Foss Electric A/S, Hillerød, Denmark). The increment of the amount of MWP added to milk led to longer RCT. In particular, significant differences were found between RCT of the control samples (13.5 min) and RCT of samples added with 3.0% (14.6 min) or more of MWP. Similar trend was observed for curd-firming time, which showed the shortest time in the control samples and the longest in samples with 9.0% (21.4 min) of MWP. No significant differences were detected for a30 across concentrations of MWP. Adjustments in cheese processing should be made when recycling MWP, in particular during coagulation process by prolonging the time of rennet activity before cutting of the curd.
Aim of the third study was to evaluate the effect of MWP, using standardized milk with different protein-to-fat ratios (PFR; high, standard and low levels of fat) and increasing MWP concentrations (from 0.0 to 4.0 %, vol/vol) on milk coagulation process, cheese yield and composition of 30 cheese samples carried out through a mini cheese-making technique. The increment of PFR affected RCT. Moreover, cheese yield decreased as the level of fat decreased, and it was higher in low-fat cheese (high PFR) with 4.0% MWP compared with low-fat cheese with 3.0% MWP. No differences were found for cheese yield in standard and high fat cheese (standard and low PFR) across MWP concentrations. The stable composition of low-fat Caciotta suggests the possibility to include MWP as fat replacer to maintain the yield.
The fourth contribute aimed at the investigating the effectiveness of Hyper Spectral Image (HSI) technique to detect MWP in low-fat Caciotta cheese, produced with increased concentration of MWP (2.0%, 3.0%, 4.0% vol/vol). Hyperspectral image is an emerging technology successfully employed in food inspection, by combining the advantages of conventional digital image and spectroscopy to obtain both spatial and spectral information from an object. Twelve mini-cheese making were performed using standardized milk in low fat condition (3.5% of protein and fat). Protein levels were adjusted with 2.0%, 3.0% or 4.0% MWP vol/vol. For each day of cheese making a control thesis without MWP was performed (0.0% MWP). After one month of ripening a slice of each cheese was analysed for the acquisition of near infrared image in range wavelengths from 1,100 to 1,600 nm, for a total of 140 wavelengths measured. Several spatial and spectral pre-processing were tested: two times spatial binning, and standard normal variate plus second derivate were select as optimal. Principal component analysis reported an explained variability of 7% across treatments. Cluster analysis evidenced an increment in component presence by increasing MWP percentage in treatments. Moreover, a score plot reported a destine classification of samples contains MWP and control without. The results confirm the ability of HIS in MWP detection, and this information can be used to construct further classification models able to discriminate cheese adulteration for MWP addition
Quantification of whey proteins by reversed phase-HPLC and effectiveness of mid-infrared spectroscopy for their rapid prediction in sweet whey
Full text linkIn the dairy industry, membrane filtration, is used to reduce the amount of whey waste and, simultaneously, to recover whey proteins (WP). The composition of WP can strongly affect the filtration treatment of whey, and rapid determination of WP fractions would be of interest for dairy producers to monitor WP recovery. This study aimed to develop mid-infrared spectroscopy (MIRS) prediction models for the rapid quantification of protein in sweet whey, using a validated rapid reversed phase (RP)-HPLC as a reference method. Quantified WP included alpha-lactalbumin (alpha-LA), beta-lactoglobulin (beta-LG) A and B, bovine serum albumin, caseinomacropeptides, and proteose peptone. Validation of RP-HPLC was performed by calculating the relative standard deviation (RSD) in repeatability and reproducibility tests for WP retention time and peak areas. Samples of liquid whey (n = 187) were analyzed by RP-HPLC and scanned through MIRS to collect spectral information (900 to 4,000 cm(-1)); statistical analysis was carried out through partial least squares regression and random cross-validation procedure. Retention times in RP-HPLC method were stable (RSD between 0.03 and 0.80%), whereas the RSD of peak area (from 0.25 to 8.48%) was affected by WP relative abundance. Higher coefficients of determination in validation for MIRS model were obtained for protein fractions present in Whey in large amounts, such as beta-Lc (0.58), total identified WP (0.58), and alpha-LA (0.56). Results of this study suggest that MIRS is an easy method for rapid quantification of detail protein in sweet whey, even if better resolution was achieved with the method based on RP-HPLC. The prediction of WP in sweet whey by MIRS might be used for screening and for classifying sweet whey according to its total and individual WP contents
Effect of microparticulated whey protein concentration and protein-to-fat ratio on Caciotta cheese yield and composition
No full textThe dairy industry exploits different processes to increase the value of whey protein (WP). Micro-particulated whey proteins (MWP), which are colloidal particles formed by controlled aggregation of WP, are widely used in low-fat products. The aim of the present study was to evaluate the effects of MWP concentration (0.0-4.0%, v/v) and different protein-to-fat ratios (PFRs) on milk coagulation process, cheese yield and composition of Caciotta cheese. Samples of cheese were analysed after 10 d of ripening. The increment of PFR affected rennet coagulation time. Moreover, cheese yield decreased as the level of fat decreased, and it was greater in low-fat cheese (high PFR) with 4.0% MWP than in low-fat cheese with 3.0% MWP. No differences were detected for cheese yield in standard and high-fat cheese (standard and low PFR) across MWP concentrations. The stable composition of low-fat Caciotta suggests the possibility to include MWP as fat replace
Evaluation of candidate reference genes for qPCR in maize
No full textQuantitative real-time PCR (qPCR) is a powerful tool to measure gene expression levels. Accurate and
reproducible results are dependent on the correct choice of the reference genes for data normalization.
To date, screenings evaluating candidate reference gene stability for expression studies in maize have
not been reported. In the present work, we analyzed the expression patterns of 12 genes in a set of 20
maize samples, obtained from different tissues of plants grown at various experimental conditions. Using
genormPLUS, NormFinder and BestKeeper algorithms, the expression stability of three “classical” reference
genes, such as ACT, TUB and 18S rRNA, and the newly identified candidates, was assessed. With respect to
the algorithms, our results showed similar performance among genormPLUS, NormFinder and BestKeeper
in evaluating the suitability of reference genes. Our data therefore showed that the currently and widely
used reference genes for data normalization in maize were not the most stable expressed transcripts. Five
of the new putative reference genes (CUL, FPGS, LUG, MEP and UBCP) exhibited the highest expression
stability according to all algorithms. In conclusion, with this study, we provide a list of validated reference
genes and their relative primer sequences to conduct reliable qPCR experiments in maize
Effect of microparticulated whey proteins on milk coagulation properties
Full text linkThe enhancement of milk coagulation properties (MCP) and the reuse of whey produced by the dairy industry are of great interest to improve the efficiency of the cheese-making process. Native whey proteins (WP) can be aggregated and denatured to obtain colloidal microparticulated WP (MWP). The objective of this study was to assess the effect of MWP on MCP; namely, rennet coagulation time (RCT), curd-firming time, and curd firmness 30 min after rennet addition. Six concentrations of MWP (vol/vol; 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0%) were added to 3 bulk milk samples (collected and analyzed during 3 d), and a sample without MWP was used as control. Within each day of analysis, 6 replicates of MCP for each treatment were obtained, changing the position of the treatment in the rack. For control samples, 2 replicates per day were performed. In addition to MCP, WP fractions were measured on each treatment during the 3 d of analysis. Milk coagulation properties were measured on 144 samples by using a Formagraph (Foss Electric, Hillerod, Denmark). Increasing the amount of MWP added to milk led to a longer RCT. In particular, significant differences were found between RCT of the control samples (13.5 min) and RCT of samples with 3.0% (14.6 min) or more MWP. A similar trend was observed for curd-firming time, which was shortest in the control samples and longest in samples with 9.0% MWP (21.4 min). No significant differences were detected for curd firmness at 30 min across concentrations of MWP. Adjustments in cheese processing should be made when recycling MWP, in particular during the coagulation process, by prolonging the time of rennet activity before cutting the curd
Study of milk coagulation properties in multibreed Italian dairy herds
No full textThe Italian dairy industry is making notable efforts to improve milk coagulation properties (MCP), as they affect
the efficiency of cheese-making process. Individual milk samples (n = 8,525) of 3,057 Holstein-Friesian (HF), Brown
Swiss (BS), and Simmental (SI) cows from 39 multibreed herds of Veneto region (northeast Italy) were collected from
September 2011 to February 2012, and evaluated for quality traits and MCP predicted by mid-infrared spectroscopy
(MIRS). Daily milk yield for each cow was also available. Milk coagulation properties were rennet coagulation time
(RCT, min) and curd firmness (a30, mm). Data were analyzed through a generalized linear mixed model including the
fixed effects of month of sampling, parity, days in milk (DIM), herd, breed, and interactions between parity and breed,
and DIM and breed. The random effects were cow nested within breed and residual. Breed and DIM were the most
important sources of variation for MCP (P < 0.001). Milk from BS cows showed the shortest RCT (19.1 min) and the
highest a30 (26.8 mm), whereas milk from HF cows had the worst MCP, with values of 21.0 min for RCT and 20.8 mm
for a30. Days in milk, breed, month of sampling, and herd effects were highly significant (P < 0.001) for all studied traits.
Results from this study indicate that, under similar environmental and management conditions, the HF exhibits less
favourable technological properties of milk than BS and SI breeds
Validation of RP-HPLC method for separation and quantification of whey protein in dairy industry by-products.
No full textEffect of cheesemaking with microparticulated whey proteins on the concentration of low molecular thiols in cheese
Full text linkAim of this work was to investigate different concentrations of microparticulated whey proteins (MWP) added during cheesemaking process on the recovery of low molecular weight thiols (LMT) in cheese. Historically, milk whey has been considered an industrial waste, because of its high cost of disposal and its polluting potential. In recent years the re - utilization of this waste represents an interesting perspective. Nowadays, several procedures are available to whey constituents recovery: some of the main are whey proteins (WP) and LMT. Whey ultrafiltration is the most common treatment to WP recovery. Thereafter, the WP undergo processes that lead to the production of protein aggregates (microparticulated-MWP), useful in different sectors of the food industry for their high gelling power and potential in LMT linkage.
Mini-cheesemaking trial using milk standardized at 3.5% of protein with 3.0% or 4.0% MWP were carried out. Cheesemaking were performed in 6 days, 3 days for each treatment. Within a day, 3 replicates of the same treatment were carried out (n = 18). The LMT of milk and whey were determined using RP - HPLC, while LMT in cheese were calculated by difference. Data were analyzed through a generalized linear model as fixed effects of the MWP concentration, replicate, and day of cheesemaking nested within MWP.
Results showed that the quantified concentration of LMT in cheese were quite stable in both the percentages of MWP. The soluble properties of LMT represent a problem in their recovery in cheese; indeed beyond a certain concentration they are not retained in the curd, but are released in the whey
Genome-wide discovery and characterization of nitrate-responsive miRNAs in roots of maize seedlings
No full textAbstract
Nitrogen availability affects crops productivity and environment. The natural abundance of useable nitrogen is so low that the massive human alteration of the nitrogen cycle has been required to sustain the feeding of the world's population. Tons of nitrogenous fertilizers are added to the soil worldwide annually, giving rise to environmental diseases. In this scenario, the knowledge of post-transcriptional regulation of plant response to nutrients is important to improve nitrogen use efficiency of crop. With the identification of stress-responsive miRNAs, a layer of post-transcriptional gene regulation has been uncovered.
We used a maize miRNAs-microarray platform to discover previously unknown nitrate-responsive miRNAs. Six mature miRNAs were identified and their expression profiles were studied by quantitative Real Time PCR (qPCR) and in situ hybridization (ISH) in maize roots grown in different nitrate availabilities.
Significant differences in miRNAs’ transcripts accumulation were evidenced between nitrate-supplied and nitrate-depleted roots. Real time PCR analyses and in situ detection of miRNAs confirmed the arrays data and evidenced distinct miRNAs spatiotemporal expression patterns in maize roots.
An in silico approach was used to select target genes of the miRNAs identified. Their transcripts accumulation has been investigated in both nitrate-supplied and nitrate-depleted roots by means of qPCR and ISH.
Our results suggest that miRNAs play some role in modulating N-responsive gene expression by inducing post-transcriptionally the expression of target genes. In particular, the repression of the transcription of miRNA identified upon nitrate shortage could represent a crucial step integrating nitrate signals into developmental changes in maize roots
A comparison of the predicted coagulation characteristics and composition of milk from multi-breed herds of Holstein-Friesian, Brown Swiss and Simmental cows
Full text linkThe milk coagulation properties (MCP) and composition, as predicted by mid-infrared spectroscopy, were compared between Holstein-Friesian (HF), Brown Swiss (BS) and Simmental (SI) cows from mixed herds. Records (n = 8524) of rennet coagulation time (RCT, min) and curd firmness (a30, mm) were analysed using a mixed linear model. Milk from BS coagulated earlier and showed a firmer curd than milk from HF and SI breeds. Rennet coagulation time was shortest in the first 90 d of lactation, and a30 was lowest at the beginning and end of lactation. Herd exerted a strong effect on MCP, as the differences between the best and the worst farm for RCT and a30 were 7.8 min and 13.1 mm, respectively. In conclusion, the BS breed produced milk more suitable for cheese production than that from SI and HF. Further research is required to understand how farm management can improve coagulation characteristics of milk
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