Influence of protein concentration and coagulation temperature on rennet-induced gelation characteristics and curd microstructure

peer-reviewedThis study characterized the coagulation properties and defined the cutting window (CW; time between storage modulus values of 35 and 70 Pa) using rheometry for milk standardized to 4, 5, or 6% protein and set at 28, 32, or 36°C. Milks were standardized to a protein-to-fat ratio of approximately 1 by blending ultrafiltration retentate, skim milk, and whole milk. The internal curd microstructure for selected curd samples was analyzed with transmission electron microscopy and scanning electron microscopy. Lowering the coagulation temperature caused longer rennet coagulation time and time to reach storage modulus of 35 Pa, translating into a wider CW. It also led to a lower maximum curd-firming rate (MCFR) with lower firmness at 40 min at a given protein level. Increasing protein levels resulted in the opposite effect, although without an effect on rennet coagulation time at a given temperature. On coagulation at 28°C, milk with 5% protein resulted in a similar MCFR (∼4 Pa/min) and CW (∼8.25 min) compared with milk with 4% protein at 32°C, which reflects more standard conditions, whereas increasing milk to 6% protein resulted in more than doubling of the curd-firming rate (MCFR = 9.20 Pa/min) and a shorter CW (4.60 min). Gels set at 28°C had lower levels of rearrangement of protein network after 40 min compared with those set at 36°C. Protein levels, on the other hand, had no influence on the levels of protein network rearrangement, as indicated by loss tangent values. The internal structure of curd particles, as investigated by both scanning electron microscopy and transmission electron microscopy, appeared to have less cross-linking and smaller casein aggregates when coagulated at 28°C compared with 36°C, whereas varying protein levels did not show a marked effect on aggregate formation. Overall, this study showed a marked interactive effect between coagulation temperature and protein standardization of milk on coagulation properties, which subsequently requires adjustment of the CW during cheesemaking. Lowering of the coagulation temperature greatly altered the curd microstructure, with a tendency for less syneresis during cutting. Further research is required to quantify the changes in syneresis and in fat and protein losses to whey due to changes in the microstructure of curd particles arising from the different coagulation conditions applied to the protein-fortified milk

Two-Rowed Hecke Algebra Representations at Roots of Unity

In this paper, we initiate a study into the explicit construction of irreducible representations of the Hecke algebra $H_n(q)$ of type $A_{n-1}$ in the non-generic case where $q$ is a root of unity. The approach is via the Specht modules of $H_n(q)$ which are irreducible in the generic case, and possess a natural basis indexed by Young tableaux. The general framework in which the irreducible non-generic $H_n(q)$-modules are to be constructed is set up and, in particular, the full set of modules corresponding to two-part partitions is described. Plentiful examples are given.Comment: LaTeX, 9 pages. Submitted for the Proceedings of the 4th International Colloquium ``Quantum Groups and Integrable Systems,'' Prague, 22-24 June 199

Influence of herd diet on the metabolome of Maasdam cheeses

peer-reviewedThe untargeted metabolic profiles of ripened Maasdam cheese samples prepared from milk derived from three herd groups, fed: (1) indoors on total mixed ration (TMR), or outdoors on (2) grass only pasture (GRA) or (3) grass and white clover pasture (CLO) were studied using high resolution nuclear magnetic resonance (1H NMR), high resolution magic angle spinning nuclear magnetic resonance (1H HRMAS NMR) and headspace (HS) gas chromatography mass spectrometry (GC-MS). A total of 31 compounds were identified using 1H NMR and 32 volatile compounds including 7 acids, 5 esters, 4 alcohols, 4 ketones, 4 sulfur compounds, 2 aldehydes, 3 hydrocarbons, 2 terpenes and a lactone were identified using GC–MS in Maasdam cheeses ripened for 97-d. On comparing the 1H NMR metabolic profiles, TMR-derived cheese had higher levels of citrate compared to GRA-derived cheese. The toluene content of cheese was significantly higher in GRA or CLO compared to TMR cheeses and dimethyl sulfide was identified only in CLO-derived cheese samples as detected using HS GC–MS. These compounds are proposed as indicator compounds for Maasdam cheese derived from pasture-fed milk. Clear differences between outdoor or indoor feeding systems in terms of cheese metabolites were detected in the lipid phase, as indicated by principal component analysis (PCA) from 1H HRMAS NMR spectra, although differences based on PCA of all 1H NMR spectra and HS-GC–MS were less clear. Overall, this study presented the metabolite profile and identified specific compounds which may be useful for discriminating between ripened Maasdam cheese and related cheese varieties manufactured from indoor or outdoor herd-feeding systems

Response surface methodology modeling of protein concentration, coagulum cut size, and set temperature on curd moisture loss kinetics during curd stirring

peer-reviewedThe effects of the independent variables protein concentration (4–6%), coagulum cut size (6–18 mm3), and coagulation temperature (28–36°C) on curd moisture loss during in-vat stirring were investigated using response surface methodology. Milk (14 kg) in a cheese vat was rennet coagulated, cut, and stirred as per semihard cheesemaking conditions. During stirring, the moisture content of curd samples was determined every 10 min between 5 and 115 min after cutting. The moisture loss kinetics of curds cut to 6 mm3 followed a logarithmic trend, but the moisture loss of curds from larger cut sizes, 12 or 18 mm3, showed a linear trend. Response surface modeling showed that curd moisture level was positively correlated with cut size and negatively correlated with milk protein level. However, coagulation temperature had a significant negative effect on curd moisture up to 45 min of stirring but not after 55 min (i.e., after cooking). It was shown that curds set at the lower temperature had a slower syneresis rate during the initial stirring compared with curds set at a higher temperature, which could be accelerated by reducing the cut size. This study shows that keeping a fixed cut size at increasing protein concentration decreased the level of curd moisture at a given time during stirring. Therefore, to obtain a uniform curd moisture content at a given stirring time at increasing protein levels, an increased coagulum cut size is required. It was also clear that breakage of the larger curd particles during initial stirring can also significantly influence the curd moisture loss kinetics. Both transmission and scanning electron micrographs of cooked curds (i.e., after 45 min of stirring) showed that the casein micelles were fused at a higher degree in curds coagulated at 36°C compared with 28°C, which confirmed that coagulation temperature causes a marked change in curd microstructure during the earlier stages of stirring. The present study showed the dynamics of curd moisture content during stirring when using protein-concentrated milk at various set temperatures and cut sizes. This provides the basis for achieving a desired curd moisture loss during cheese manufacture using protein-concentrated milk as a means of reducing the effect of seasonal variation in milk for cheesemaking

A national appraisal of haemodialysis vascular access provision in Scotland

Purpose: Published registry data demonstrate longstanding variation in the utilisation of different vascular access (VA) modalities between Scottish renal units; this may reflect different clinical processes between centres. A comprehensive appraisal was undertaken to understand the processes underpinning VA creation and maintenance across Scotland. Methods: A mixed methods approach was utilised. Fifty-two semi-structured interviews were conducted with patients and clinicians in all ten, adult and paediatric, Scottish renal units. Interview transcripts were subjected to thematic analysis. Clinical activity data were prospectively collected for six weeks, and correlated with registry data. Results: VA accounts for a large clinical workload. There was significant inter-centre variation in the utilisation of different VA modalities, and patients described frustrating, dissatisfying experiences. VA creation and maintenance pathways functioned best when nephrologists, surgeons and radiologists were co-located on the same campus with close multi-disciplinary working, protected clinical time, and proactive VA maintenance. No unit routinely measured or discussed procedure outcomes or strategic aspects of their service. Conclusions: Varied clinical outcomes reflected varied clinical processes. Optimised clinical pathways, staff education and measurement of clinical outcomes may improve VA service quality and facilitate safer, more effective, patient-centred care

Measurement of syneretic properties of rennet-induced curds and impact of factors such as concentration of milk: A review

peer-reviewedBackground The rate or extent of whey expulsion or syneresis from cheese curds during stirring in-vat determines curd moisture levels, which subsequently influences cheese moisture content. The outward migration of whey depends on curd contraction and on the structure of the pores permitting whey movement. Curd syneretic properties are one of the least understood areas of cheese science, particularly when milk of varying composition is used. Scope and approach This review provides an insight into the mechanisms of curd formation and curd syneresis, and factors influencing syneretic properties in unconcentrated and concentrated milk and appraises syneresis measurement methods in terms of their relative strengths and weaknesses. Key findings and conclusions Direct measurement of moisture content of curds is recommended as a simple and reliable method for measurement of syneresis of industrial relevance and, although inline measurement for curd moisture prediction has been a significant development in the last decade, its application to commercial production is still limited. A review of previous studies found that experimental conditions and methodologies used to measure syneresis vary widely, making it difficult to compare data between studies. Overall, interactions between process variables employed determines whether syneresis is accentuated or inhibited, and this can be exploited by cheese producers to attain target curd moisture contents by varying process parameters, particularly when milk is concentrated prior to cheese-making. Furthermore, further studies should be focused on endogenous syneresis and casein network rearrangement to clearly elucidate this mechanism and its influence on macrosyneresis under dynamic conditions

Monitoring Metropolitan Growth Dynamics for Achieving Sustainable Urbanization (SDG 11.3) in Kolkata Metropolitan Area, India

From MDPI via Jisc Publications RouterHistory: accepted 2021-10-29, pub-electronic 2021-11-03Publication status: PublishedThe mass accumulation of population in the larger cities of India has led to accelerated and unprecedented peripheral urban expansion over the last few decades. This rapid peripheral growth is characterized by an uncontrolled, low density, fragmented and haphazard patchwork of development popularly known as urban sprawl. The Kolkata Metropolitan Area (KMA) has been one of the fastest-growing metropolitan areas in India and is experiencing rampant suburbanization and peripheral expansion. Hence, understanding urban growth and its dynamics in these rapidly changing environments is critical for city planners and resource managers. Furthermore, understanding urban expansion and urban growth patterns are essential for achieving inclusive and sustainable urbanization as defined by the United Nations in the Sustainable Development Goals (e.g., SDGs, 11.3). The present research attempts to quantify and model the urban growth dynamics of large and diverse metropolitan areas with a distinct methodology considering the case of KMA. In the study, land use and land cover (LULC) maps of KMA were prepared for three different years (i.e., for 1996, 2006, and 2016) through the classification of Landsat imagery using a support vector machine (SVM) classification approach. Then, change detection analysis, landscape metrics, a concentric zone approach, and Shannon’s entropy approach were applied for spatiotemporal assessment and quantification of urban growth in KMA. The achieved classification accuracies were found to be 89.75%, 92.00%, and 92.75%, with corresponding Kappa values of 0.879, 0.904, and 0.912 for 1996, 2006, and 2016, respectively. It is concluded that KMA has been experiencing typical urban sprawl. The peri-urban areas (i.e., KMA-rural) are growing rapidly, and are characterized by leapfrogging and fragmented built-up area development, compared to the central KMA (i.e., KMA-urban), which has become more compact in recent years

Correction to: HIF prolyl hydroxylase inhibition protects skeletal muscle from eccentric contraction induced injury

Following publication of the original article [1], the authors flagged that there is a discrepancy with the Availability of data and materials statement on page 12 of the article