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Multivariate multiple linear regression (MMLR), which occurs in a number of practical applications, generalizes traditional least squares (multivariate linear regression) to multiple right-hand sides. We extend recent MLR analyses to sketched MMLR in general Schatten p -norms by interpreting the sketched problem as a multiplicative perturbation. Our work represents an extension of Maher's results on Schatten p -norms. We derive expressions for the exact and perturbed solutions in terms of projectors for easy geometric interpretation. We also present a geometric interpretation of the action of the sketching matrix in terms of relevant subspaces. We show that a key term in assessing the accuracy of the sketched MMLR solution can be viewed as a tangent of a largest principal angle between subspaces under some assumptions. Our results enable additional interpretation of the difference between an orthogonal and oblique projector with the same range. [ABSTRACT FROM AUTHOR]

It is essential to focus on how older adults remain active and regain control of their daily lives after hip fractures. 'Rehabilitation of Life' is an empowerment-orientated hip fracture intervention focused on continuous rehabilitation and care between sectors in Denmark. We aimed to understand and explore older adults' experience participating in the intervention 'Rehabilitation of Life' and how this relates to their sense of empowerment. Qualitative data were generated from 16 semi-structured interviews with patients experiencing a hip fracture and subsequent rehabilitation in the program "Rehabilitation of Life' The data was analysed using Graneheim and Lundman's concept-guided qualitative content analysis method. The analysis revealed five themes that the participants emphasised as vital to their rehabilitation: getting information and care when hospitalised, early visits from healthcare professionals after returning to their homes, the social aspect of training together with others, rehabilitation provision by skilled and empathic staff, and acceptance of a new me. The five themes indicated that adults aged >65 years generally experienced rehabilitation after hip fractures as motivating and reassuring. Social support and peer programs can significantly improve the rehabilitation of older adults with hip fractures. The Rehabilitation of Life intervention has shown that promoting successful rehabilitation requires patient-centred strategies that encourage collaboration between different sectors. To increase patients' empowerment and engagement in their health journey, it is important to consider changes in patients' behaviour, increase their autonomy and ensure their independence after rehabilitation. • Hip fractures impact a patient's everyday life, and rehabilitation often emphasizes the physical and medical aspects. • Patients need physiological and psychosocial aspects prioritised in rehabilitation. • Health education empowers patients and contributes to rehabilitation. • Empowering older adults improves their quality of life and maintains independence. • An empowerment-oriented hip fracture intervention may be a solution. [ABSTRACT FROM AUTHOR]

Background Barrett's esophagus (BE)—intestinal metaplasia in the esophagus—may progress to low-grade dysplasia (LGD), high-grade dysplasia (HGD), and ultimately, invasive esophageal adenocarcinoma (EAC). The course of BE in immunosuppressed lung transplant recipients is unknown. Methods This study retrospectively reviewed the records of patients who underwent lung transplant at a single center, Norton Thoracic Institute in Phoenix, Arizona, between January 1, 2010 and October 31, 2016. Pretransplant esophagram, esophagogastroduodenoscopy, 24-hour pH monitoring, high-resolution manometry, and gastric emptying studies were analyzed. Results Of the 466 patients who underwent lung transplant during the study period, 54 (11.59%) had BE on pretransplant esophagogastroduodenoscopy. Of these, 1 patient had HGD before lung transplant. The median age of patients was 64 years (interquartile range, 58.25 to 68.75 years); 66.7% were men. Median follow-up duration was 29.48 months (interquartile range, 19.69 to 37.98 months). Sixteen of 54 patients (29.62%) underwent antireflux surgery after lung transplant. LGD or EAC developed in 3 patients during posttransplant surveillance. One patient had a diagnosis of HGD 24 months after retransplant. She underwent complete endoscopic ablation and was dysplasia-free for 5 months, but ultimately the condition recurred, and she underwent esophagectomy for invasive cancer. Two patients had a diagnosis of LGD 7 and 13 months after lung transplant and were successfully treated with radiofrequency ablation. The rate of progression to dysplasia or EAC was 2.3% per patient-year. Conclusions BE seems to be more prevalent in lung transplant recipients than in the general population. The study findings suggest that patients with BE have a higher risk of BE-to-EAC progression after lung transplant and that HGD may progress rapidly in immunosuppressed patients. More intensive surveillance endoscopy may be required in patients with BE after lung transplant. [ABSTRACT FROM AUTHOR]

Summary Mammalian sphingolipids, primarily with C24 or C16 acyl chains, reside in the outer leaflet of the plasma membrane. Curiously, little is known how C24 sphingolipids impact cholesterol and membrane microdomains. Here, we present evidence that C24 sphingomyelin, when placed in the outer leaflet, suppresses microdomains in giant unilamellar vesicles and also suppresses submicron domains in the plasma membrane of HeLa cells. Free energy calculations suggested that cholesterol has a preference for the inner leaflet if C24 sphingomyelin is in the outer leaflet. We indeed observe that cholesterol enriches in the inner leaflet (80%) if C24 sphingomyelin is in the outer leaflet. Similarly, cholesterol primarily resides in the cytoplasmic leaflet (80%) in the plasma membrane of human erythrocytes where C24 sphingolipids are naturally abundant in the outer leaflet. We conclude that C24 sphingomyelin uniquely interacts with cholesterol and regulates the lateral organization in asymmetric membranes, potentially by generating cholesterol asymmetry. [ABSTRACT FROM AUTHOR]

Western diets, high in fat and energy, are associated with cognitive deficits in humans and animal models, but the underlying mechanisms are not fully elucidated. This includes whether diet-induced dyslipidemia per se negatively impacts brain signaling. Here we investigate the effects of dyslipidemia induced by two high fat diets with or without high sucrose on hippocampal and frontal cortical oxidative stress, brain-derived neurotrophic factor (BDNF) and down-stream markers of synaptic plasticity, as well as alterations in monoaminergic neurotransmitter levels. A high fat diet was associated with decreased antioxidant status (vitamin C), increased serotonin in the frontal cortex, and increased ratio of phosphorylated Ca 2+ /calmodulin-dependent protein kinase II in the hippocampus, while a high fat and sucrose diet decreased levels of vitamin C in the frontal cortex and BDNF in the hippocampus. Markers of dyslipidemia correlated significantly with cerebral vitamin C levels, monoaminergic neurotransmitters and metabolites in the frontal cortex, but not in the hippocampus. Thus, a high fat diet caused regional alterations in antioxidant levels, neurochemistry and molecular markers in the non-obese dyslipidemic guinea pig. [ABSTRACT FROM AUTHOR]

Purpose To describe our magnetic resonance imaging (MRI) simulated implementation of the 4D digital extended cardio torso (XCAT) phantom to validate our previously developed cardiac tracking techniques. Real-time tracking will play an important role in the non-invasive treatment of atrial fibrillation with MRI-guided radiosurgery. In addition, to show how quantifiable measures of tracking accuracy and patient-specific physiology could influence MRI tracking algorithm design. Methods Twenty virtual patients were subjected to simulated MRI scans that closely model the proposed real-world scenario to allow verification of the tracking technique’s algorithm. The generated phantoms provide ground-truth motions which were compared to the target motions output from our tracking algorithm. The patient-specific tracking error, e p , was the 3D difference (vector length) between the ground-truth and algorithm trajectories. The tracking errors of two combinations of new tracking algorithm functions that were anticipated to improve tracking accuracy were studied. Additionally, the correlation of key physiological parameters with tracking accuracy was investigated. Results Our original cardiac tracking algorithm resulted in a mean tracking error of 3.7 ± 0.6 mm over all virtual patients. The two combinations of tracking functions demonstrated comparable mean tracking errors however indicating that the optimal tracking algorithm may be patient-specific. Conclusions Current and future MRI tracking strategies are likely to benefit from this virtual validation method since no time-resolved 4D ground-truth signal can currently be derived from purely image-based studies. [ABSTRACT FROM AUTHOR]

Organizations develop and adapt to societal changes and technological developments, where one consequence is that dispersed workers are more common than never before. It is difficult to ensure employee wellbeing and performance, when separating managers from employees by either time or geography. This paper explores the wellbeing of employees doing distance work, and examines the practices of the distance manager aimed at ensuring employee wellbeing and organizational performance. The pilot study use a case study approach in four organizations with qualitative interviews of distance managers and employees. The study show both positive and negative aspects of distance work. Positively, the employees find distance work to be professionally challenging and they feel they make a difference in their work. On the negative side is the feeling of loneliness and frustrations about lack of communication. The analysis of distance managers’ practices showed that they used both activities and capabilities in order to ensure employee wellbeing and organizational performance. The activities included planning, newsletters, and surveys, and the capabilities were to listen, create and show trust, and give authority to the employees. Contrary to previous findings on motivating of knowledge workers, our findings show that motivation, surprisingly, is ensured when focusing on the basic needs such as working conditions and belongingness. [ABSTRACT FROM AUTHOR]

Foods consist of a large number of different nutrients that are contained in a complex structure. The nature of the food structure and the nutrients therein (i.e., the food matrix) will determine the nutrient digestion and absorption, thereby altering the overall nutritional properties of the food. Thus, the food matrix may exhibit a different relation with health indicators compared to single nutrients studied in isolation. The evidence for a dairy matrix effect was presented and discussed by an expert panel at a closed workshop, and the following consensus was reached: 1) Current evidence does not support a positive association between intake of dairy products and risk of cardiovascular disease (i.e., stroke and coronary heart disease) and type 2 diabetes. In contrast, fermented dairy products, such as cheese and yogurt, generally show inverse associations. 2) Intervention studies have indicated that the metabolic effects of whole dairy may be different than those of single dairy constituents when considering the effects on body weight, cardiometabolic disease risk, and bone health. 3) Different dairy products seem to be distinctly linked to health effects and disease risk markers. 4) Different dairy structures and common processing methods may enhance interactions between nutrients in the dairy matrix, which may modify the metabolic effects of dairy consumption. 5) In conclusion, the nutritional values of dairy products should not be considered equivalent to their nutrient contents but, rather, be considered on the basis of the biofunctionality of the nutrients within dairy food structures. 6) Further research on the health effects of whole dairy foods is warranted alongside the more traditional approach of studying the health effects of single nutrients. Future diet assessments and recommendations should carefully consider the evidence of the effects of whole foods alongside the evidence of the effects of individual nutrients. Current knowledge gaps and recommendations for priorities in future research on dairy were identified and presented. [ABSTRACT FROM AUTHOR]

Use of microparticulated whey protein (MWP) was patented in 1988; since then much research has been conducted on use of MWP. This review provides an overview of the use and functionality of MWP in dairy applications and discusses how MWP interacts with other components in dairy matrices. For fermented dairy products, fine-tuning of the interaction potential of MWP is of major importance. For products where MWP serves as an inert filler (e.g., cheese, ice cream), initial processing should ensure that MWP will not interact with the product matrix ensuring creaminess and desired structural weakening. Future research should focus on how raw material composition and processing affect the properties of MWP, on the role of particle characteristics on interactions with other dairy product components, and on how to develop particulated ingredients suitable for high protein products and further clarifying the role of MWP in ensuring creaminess in complex dairy matrices. [ABSTRACT FROM AUTHOR]

Random matrices formed from i.i.d. standard real Gaussian entries have the feature that the expected number of real eigenvalues is non-zero. This property persists for products of such matrices, independently chosen, and moreover it is known that as the number of matrices in the product tends to infinity, the probability that all eigenvalues are real tends to unity. We quantify the distribution of the number of real eigenvalues for products of finite size real Gaussian matrices by giving an explicit Pfaffian formula for the probability that there are exactly k real eigenvalues as a determinant with entries involving particular Meijer G -functions. We also compute the explicit form of the Pfaffian correlation kernel for the correlation between real eigenvalues, and the correlation between complex eigenvalues. The simplest example of these — the eigenvalue density of the real eigenvalues — gives by integration the expected number of real eigenvalues. Our ability to perform these calculations relies on the construction of certain skew-orthogonal polynomials in the complex plane, the computation of which is carried out using their relationship to particular random matrix averages. [ABSTRACT FROM AUTHOR]

Chronic dyslipidemia imposed by a high-fat and high-caloric dietary regime leads to debilitating disorders such as obesity, nonalcoholic fatty liver disease (NAFLD), and insulin resistance. As disease rates surge, so does the need for high validity animal models to effectively study the causal relationship between diet and disease progression. The dyslipidemic guinea pig displays a high similarity with the human lipoprotein profile and may in this aspect be superior to other rodent models. This study investigated the effects of 2 long-term Westernized diets (0.35% cholesterol, 18.5% vegetable oil and either 15% or 20% sucrose) compared with isocaloric standard chow in adult guinea pigs. Biochemical markers confirmed dyslipidemia in agreement with dietary regimens; however, both high-fat groups displayed a decreased tissue fat percentage compared with controls. Macroscopic appearance, histopathologic evaluation, and plasma markers of liver function confirmed NAFLD in high-fat groups, supported by liver redox imbalance and markers suggesting hepatic endothelial dysfunction. Plasma markers indicated endothelial dysfunction in response to a high-fat diet, although atherosclerotic lesions were not evident. Evaluation of glucose tolerance showed no indication of insulin resistance. The 5% increase in sucrose between the 2 high-fat diets did not lead to significant differences between groups. In conclusion, we find the dyslipidemic guinea pig to be a valid model of diet imposed dyslipidemia, particularly with regards to hepatic steatosis and endothelial dysfunction. Furthermore, the absence of obesity supports the present study setup as targeting NAFLD in nonobese individuals. [ABSTRACT FROM AUTHOR]

• Additional cases of Stone Heart were reported the last decade with fatal outcome • Stone Heart developed in pigs after 180 minutes of aortic cross-clamp time • Early morphologically damage of cardiomyocyte must be studied with electron microscopy • The transition state should be further researched for improvement of cardioplegic regime in cardiac surgery To investigate Stone Heart Syndrome (SHS) as consequence of prolonged ischemic arrest in an experimental study on pigs in regards to onset of SHS and pathological changes. Outcomes defined as aortic cross clamp (ACC) time until onset of SHS and cellular changes characterized by SHS. Eight pigs were included to undergo normothermic cardioplegia induced cardiac arrest ranging from 80 to 240 minutes of ACC. Duration of ACC was defined as time from initiation of aortic cross clamping until cessation. Normothermic, cardioplegic solution administered directly into the arterial system, though in a reduced dose compared to clinical practice. Myocardial contracture evaluated by palpation of the myocardium. Biopsies were collected from the left ventricle just after the induction of cardiac arrest and after reperfusion. Biopsies were evaluated for pathological changes indicative of SHS by electron microscopy. Six pigs completed the full trial, while two were lost to bleeding. Pigs undergoing 80 to 120 minutes of ACC regained heart rhythm either spontaneously or after defibrillation. Pigs undergoing more than 180 minutes of ACC had contracted hearts with no electrocardiographic response indicating the development of SHS. Electron microscopy findings after ACC of 80 to 120 minutes showed no or low degrees of cellular changes, whereas pig hearts with more than 180 minutes of ACC showed severe mitochondrial changes, endothelial damage, and shortening of sarcomeres consistent with SHS. Development of SHS in pigs was ACC time dependent and solely avoided when ACC was limited to a maximum of 120 minutes. [ABSTRACT FROM AUTHOR]

Purpose To examine the most common presenting complaints of active-duty service members with isolated dorsal wrist ganglions and to determine the rate of return to unrestricted duty after open excision. Methods Surgical records at 2 military facilities were screened to identify male and female active duty service members undergoing isolated open excision of dorsal wrist ganglions from January 1, 2006 to January 1, 2014. Electronic medical records and service disability databases were searched to identify the most common presenting symptoms and to determine whether patients returned to unrestricted active duty after surgery. Postoperative outcomes examined were pain persisting greater than 4 weeks after surgery, stiffness requiring formal occupational therapy treatment, surgical wound complications, and recurrence. Results A total of 125 active duty military personnel (Army, 54; Navy, 43; and Marine Corps, 28) met criteria for inclusion. Mean follow-up was 45 months. Fifteen percent (8 of 54) of the Army personnel were given permanent waivers from performing push-ups owing to persistent pain and stiffness. Pain persisting greater than 4 weeks after surgery was an independent predictor of eventual need for a permanent push-up waiver. The overall recurrence incidence was 9%. No demographic or perioperative factors were associated with recurrence. Conclusions Patients whose occupation or activities require forceful wrist extension should be counseled on the considerable risk of residual pain and functional limitations that may occur after open dorsal wrist ganglion excision. Type of study/level of evidence Therapeutic IV. [ABSTRACT FROM AUTHOR]

Ectopic banking of amputated parts is a recognized technique for delayed replantation of an amputated part when the amputation stump will not permit immediate replantation. This is conventionally performed with the intent of transferring the injured part back to its anatomic position when the amputation stump is more appropriate for replantation. Current warfare conditions have led to a commonly encountered military trauma injury pattern of multiple extremity amputations with protected trunk and core structures. This pattern poses many challenges, including the limit or absence of donor sites for immediate or delayed flap reconstructive procedures. We describe a case in which we ectopically banked the great toe of an amputated lower extremity for delayed thumb reconstruction. [Copyright &y& Elsevier]

Abstract: Background: Adults with disabilities experience a variety of secondary health conditions that have a negative association with employment. Vocational rehabilitation (VR) provides one possible access point for providing health promotion activities to help clients manage these conditions. Objective: To build the case for providing health promotion services in the VR setting, this research assesses how secondary health conditions impact employment closures over time for VR clients. Specifically, we hypothesize that higher rates of secondary conditions will be negatively associated with employment outcomes at 18 months. Methods: VR clients with physical disability (n = 162) provided longitudinal data at baseline and at 6, 12, and 18 months. Two binary logistic regression models used self-report data to predict employment outcomes. The first model used explanatory variables measured at baseline or prior to receiving VR services, and the second model measured variables after 18 months in the VR program. Both models included variables to control for demographic characteristics, disability severity, baseline employment, and receipt of social insurance payments. The second model also included variables to account for VR services received. Results: Both models showed that higher reported rates of secondary conditions were associated with lower probabilities of employment (p = .012; p = .022). The expanded model also showed that receipt of counseling services through VR increased the probability of employment (p = .04) and that receipt of medical services through VR reduced the probability of employment (p = .02). Conclusions: VR can improve client employment outcomes through expanded counseling and guidance services or possibly through improved access to health promotion programming that helps clients manage secondary health conditions. [Copyright &y& Elsevier]

Abstract: Objective/hypothesis: We conducted a review of four health behavior change (HBC) theories (Health Belief, Theory of Planned Behavior, Social Cognitive, and Transtheoretical) to consider how these theories conceptually apply to people with disabilities. Methods: We identified five common constructs across HBC theories and examined how these commonalities fit within the International Classification of Function (ICF). Results: Four of the HBC constructs appear to be Personal Factors within the ICF, while the fifth represents Environmental Factors. Conclusions: Using the ICF framework to understand disability and HBC, we propose that including a sense of meaning as another personal factor will further develop HBC theories that lead to more effective HBC interventions for people with disabilities. [Copyright &y& Elsevier]

Abstract: Lipid-bilayer membranes are formed by self-assembly processes. The molecular interactions within the bilayer and with the environment impart a unique trans-bilayer lateral pressure profile and provide a set of physical mechanisms for formation of lipid domains and laterally differentiated regions in the plane of the membrane. Results from a number of experimental and theoretical studies of model lipid bilayers are reviewed, emphasizing the significance of these fundamental physical properties for the structure and dynamics of biological membranes. Particular attention is paid to the relevance of postulating the existence of equilibrium thermodynamic phases in biological membranes. This includes a discussion of the possible significance of equilibrium critical points in biological membrane systems that normally exist under non-equilibrium conditions. The need for a new model to replace the celebrated Nicolson–Singer fluid-mosaic model of biological membranes is also discussed. [Copyright &y& Elsevier]

Abstract: We review the fundamental strategies used by small peptides to associate with lipid membranes and how the different strategies impact on the structure and dynamics of the lipids. In particular we focus on the binding of amphiphilic peptides by electrostatic and hydrophobic forces, on the anchoring of peptides to the bilayer by acylation and prenylation, and on the incorporation of small peptides that form well-defined channels. The effect of lipid–peptide interactions on the lipids is characterized in terms of lipid acyl-chain order, membrane thickness, membrane elasticity, permeability, lipid-domain and annulus formation, as well as acyl-chain dynamics. The different situations are illustrated by specific cases for which experimental observations can be interpreted and supplemented by theoretical modeling and simulations. A comparison is made with the effect on lipids of trans-membrane proteins. The various cases are discussed in the context of the possible roles played by lipid–peptide interactions for the biological, physiological, and pharmacological function of peptides. [Copyright &y& Elsevier]

Abstract: Hydrolysis of the whey protein α-lactalbumin with a specific serine protease has been shown to result in regular nanotubes of approximately 20 nm in outer diameter and reaching several μm in length. Tubular assembly depends on the concentration of protein as this determines how far the hydrolysis proceeds. A concentration of 30 g L−1 is a prerequisite for tubular formation, as is a minimum concentration of calcium. At lower protein concentrations calcium-independent formation of linear fibrils (∼5 nm in diameter) is favoured. Possible applications of α-lactalbumin nanotubes include use as a viscosifier and gelling agent and also pharmaceutical utilization (such as targeted drug release) and use in nanotechnology can be envisioned. [Copyright &y& Elsevier]

Background Context: Anterior cervical plates are commonly used to provide immediate stabilization after a variety of cervical spine procedures. It has been assumed that the ideal position for anterior cervical spine plates is centered in the horizontal plane without significant angulation and without overlap of adjacent unfused levels. Nevertheless, postoperative radiographs often demonstrate actual plate position to be lateralized, rotated, or encroaching on the adjacent disc space. There have been no reported systematic studies examining the effect of variations in plate position in a large clinical population. Purpose: To evaluate the association between plate position and short-term clinical outcomes after anterior cervical discectomy and instrumented fusion (ACDF). Study Design/setting: Review of prospectively collected clinical outcomes measures and radiographs. Patient Sample: Patients undergoing ACDF surgery by a group of spine surgical specialists at a single institution. Outcome Measures: Direct and calculated plain radiographic measurements, visual analog scores for neck and arm pain, and SF-36 scores. Methods: The study population included 200 patients undergoing a one-, two-, or three-level ACDF with instrumentation. Thirteen separate direct measurements and two calculated values of plate position on immediate postoperative radiographs, including lateralization, rotation, and proximity to adjacent disc spaces, were performed in blinded fashion by 3 independent reviewers. Statistical correlation with prospectively collected patient outcomes measures, including VAS for neck and arm pain and SF-36 scores, was performed. Results: In the study population, average plate position was 3.3 mm from the cephalad disc space, 6.4 mm from the caudal disc space, 3.9 degrees angulation in the frontal plate, and 26% laterally displaced from the midline. At average 18.6 months of follow-up, no significant association was identified between any plate position measure and clinical outcomes. Conclusions: The use of anterior cervical plating by experienced spine surgeons is associated with variation in terms of plate position on postoperative radiographs. Within the range of positions analyzed in this study, no significant association was found between lateralized or rotated plates or plates placed in proximity to adjacent disc spaces and worse short-term clinical outcomes. It should be emphasized that these results and conclusions are based on relatively short-term clinical follow-up and that the long-term effects of variation in implant position remain unknown. [ABSTRACT FROM AUTHOR]

Abstract: Milk concentrates are used in the production of cast cheese. The effects of pH (5.19–6.21) and NaCl concentration (0, 1.75% and 3.50%, w/w) on the rheological and microstructural properties of rennet-induced casein gels made from ultra filtered skim milk (19.8%, w/w casein) were investigated. Low pH and high NaCl concentration reduced the development rate of the gel elasticity after coagulation of the ultra filtrated skim milk. Strain at fracture and stress at fracture from uniaxial compression of casein gels 48h after coagulation showed maximum and minimum values at pH ∼5.8 and 5.29, respectively. Young''s modulus from uniaxial compression of the same gels was almost constant between pH 5.52 and 6.21 but much lower at pH 5.28. Addition of NaCl resulted in increased Young''s modulus in the interval pH 6.21–5.52. As pH decreased, the level of colloidal calcium phosphate decreased concomitantly, giving less cross-links in the casein network and partly explaining the changes in the rheological properties. Increased ionic strength by adjusting pH and addition of NaCl also influenced rheological results. The microstructure examined with confocal laser-scanning microscopy was unaffected by the changes in pH and concentrations of NaCl in the range studied as revealed by image analysis and calculations of two- and three-dimensional data from micrographs. [Copyright &y& Elsevier]

Abstract: Rennet induced coagulation of ultrafiltrated (UF) skim milk (19.8%, w/w casein) at pH 5.8 was studied and compared with coagulation of unconcentrated skim milk of the same pH. At the same rennet concentration (0.010 International Milk Clotting Units g−1), coagulation occurred at a slower rate in UF skim milk but started at a lower degree of κ-casein hydrolysis compared with the unconcentrated skim milk. Confocal laser scanning micrographs revealed that large aggregates developed in the unconcentrated skim milk during renneting. Following extensive microsyneresis the protein strands were shorter and thinner in gels from UF skim milk. Moreover, during storage up to 60 days (13°C), the microstructure and the size of the protein strands of the UF gel changed only slightly. Hoelter–Foltmann plots suggested that the coagulation rate was reduced in the UF skim milk due to a high zero shear viscosity of the concentrate compared with the unconcentrated skim milk. [Copyright &y& Elsevier]

The properties of casein micelles in milk concentrates are of interest for the use of ultrafiltered (UF) skim milk concentrates in dairy products, and for the general understanding of colloidal stability and behavior of the casein micelle. The rheological behavior of UF skim milk concentrate with a casein concentration of 19.5% (wt/wt) was investigated at different pH and NaCl concentrations by analyzing flow viscometry and small amplitude oscillatory shear measurements. Viscometric flow curves were fitted to the Carreau-Yasuda model with the aim of determining values for the viscosity at infinite high shear rates and thereby estimate the voluminosity of the casein micelles (vcasein) in the UF concentrate. The voluminosity of the casein micelles increased with addition of NaC1 and decreased when pH was decreased from 6.5 to 5.5. At pH 5.2, vcasein increased because of acid-induced aggregation of the casein micelles. The changes in vcasein could be interpreted from transmission electron microscopy of freeze-fractured samples of the UF concentrate and partly from dynamic light scattering measurements. Altered interactions between casein micelles due to different pH and NaCl concentrations are proposed to occur due to collapse of the κ-casein layer, changed ionic strength, and altered distance between casein micelles. [ABSTRACT FROM AUTHOR]