Depression and fatigue six months post-COVID-19 disease are associated with overlapping symptom constellations: A prospective, multi-center, population-based cohort study.

BACKGROUND: Depression and fatigue are commonly observed sequelae following viral diseases such as COVID-19. Identifying symptom constellations that differentially classify post-COVID depression and fatigue may be helpful to individualize treatment strategies. Here, we investigated whether self-reported post-COVID depression and post-COVID fatigue are associated with the same or different symptom constellations. METHODS: To address this question, we used data from COVIDOM, a population-based cohort study conducted as part of the NAPKON-POP platform. Data were collected in three different German regions (Kiel, Berlin, Würzburg). We analyzed data from >2000 individuals at least six months past a PCR-confirmed COVID-19 disease, using elastic net regression and cluster analysis. The regression model was developed in the Kiel data set, and externally validated using data sets from Berlin and Würzburg. RESULTS: Our results revealed that post-COVID depression and fatigue are associated with overlapping symptom constellations consisting of difficulties with daily activities, perceived health-related quality of life, chronic exhaustion, unrestful sleep, and impaired concentration. Confirming the overlap in symptom constellations, a follow-up cluster analysis could categorize individuals as scoring high or low on depression and fatigue but could not differentiate between both dimensions. LIMITATIONS: The data presented are cross-sectional, consisting primarily of self-reported questionnaire or medical records rather than biometric data. CONCLUSIONS: In summary, our results suggest a strong link between post-COVID depression and fatigue, highlighting the need for integrative treatment approaches.

Predictors of non-recovery from fatigue and cognitive deficits after COVID-19: a prospective, longitudinal, population-based study.

Background: Despite the high prevalence and major disability associated with fatigue and cognitive deficits after SARS-CoV-2 infection, little is known about long-term trajectories of these sequelae. We aimed to assess long-term trajectories of these conditions and to identify risk factors for non-recovery. Methods: We analyzed longitudinal data from the population-based COVIDOM/NAPKON-POP cohort in Germany. Participants with confirmed SARS-CoV-2 infection were assessed at least 6 months (baseline) and again at least 18 months (follow-up) after infection using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) Scale (cutoff ≤ 30) and the Montreal Cognitive Assessment (MoCA, cutoff ≤ 25). Predictors of recovery from fatigue or cognitive deficits between assessments were identified through univariate and multivariable logistic regression models. The COVIDOM study is registered at the German registry for clinical studies (DRKS00023742) and at ClinicalTrials.gov (NCT04679584). Findings: Between 15 November 2020 and 9 May 2023, a total of 3038 participants were assessed at baseline (median 9 months after infection) and 83% responded to invitations for follow-up (median 26 months after infection). At baseline, 21% (95% confidence interval (CI) [20%, 23%]) had fatigue and 23% (95% CI [22%, 25%]) had cognitive deficits according to cutoff scores on the FACIT-Fatigue or MoCA. Participants with clinically relevant fatigue (at baseline) showed significant improvement in fatigue scores at follow-up (Hedges' g [95% CI] = 0.73 [0.60, 0.87]) and 46% (95% CI [41%, 50%]) had recovered from fatigue. Participants with cognitive deficits showed a significant improvement in cognitive scores (g [95% CI] = 1.12 [0.90, 1.33]) and 57% (95% CI [50%, 64%]) had recovered from cognitive deficits. Patients with fatigue exhibiting a higher depressive symptom burden and/or headache at baseline were significantly less likely to recover. Significant risk factors for cognitive non-recovery were male sex, older age and <12 years of school education. Importantly, SARS-CoV-2 reinfection had no significant impact on recovery from fatigue or cognitive deficits. Interpretation: Fatigue and cognitive deficits are common sequelae after SARS-CoV-2 infection. These syndromes improved over time and about half of the patients recovered within two years. The identified risk factors for non-recovery from fatigue and cognitive deficits could play an important role in shaping targeted strategies for treatment and prevention. Funding: Funded by the German Federal Ministry of Education and Research (BMBF; grant number 01KX2121) and German Research Foundation (DFG) Excellence Cluster "Position Medicine in Information".

Do Basic Neurologic Assessments Tell Us More Than We Realize?

BACKGROUND: Neurologic assessments using a monofilament and a tuning fork are routinely performed to screen for peripheral neuropathy and to identify foot ulceration and amputation risks. We investigated whether assessments commonly used to monitor sensation in the feet may illuminate a more holistic perspective of a person's overall health status. METHODS: Recruitment of 50 participants for foot health screening was facilitated via a promotional event for Foot Health Week. Participants were aged 52 to 92 years (31 women and 19 men). Monofilament and tuning fork assessments were used to determine each participant's neurologic status. Participants also completed a modified Foot Health Status Questionnaire. Data were analyzed to identify correlations between neurologic assessment results and questionnaire responses. RESULTS: For participants self-reporting an "excellent" health rating, a significant relationship was identified with adequate vibration sensation (P < .01). Significant correlations were also identified between a greater number of sites detected using a 10-g monofilament assessment and a person's experience of having a lot of energy (P = .03), limited interference with social activities (P = .03), and greater confidence completing a variety of functional tasks. CONCLUSIONS: Significant correlations were observed between basic neurologic assessments and a participant's perception of their overall health. Although these findings reflect a correlational rather than a causational relationship, they may provide a stimulus for clinicians to reflect on the holistic value of peripheral neurologic assessment. Although the immediate focus for a practitioner is minimizing risk and preserving tissue viability, neurologic test results may be useful to stimulate further discussion about a patient's health outcomes by exploring issues beyond the presenting condition.

Systematic review on the effectiveness of mobile health applications on mental health of breast cancer survivors.

PURPOSE: Breast cancer survivors are more likely to report psychological distress and unmet need for support compared to healthy controls. Psychological mobile health interventions might be used in follow-up care of breast cancer patients to improve their mental health. METHODS: We searched MEDLINE, PsychINFO, Cochrane and PROSPERO for articles on controlled trials examining the effectiveness of psychological mobile health interventions compared to routine care regarding mental health outcomes of adult breast cancer survivors. This review followed the PRISMA statement and was registered on PROSPERO (CRD42022312972). Two researchers independently reviewed publications, extracted data and assessed risk of bias. RESULTS: After screening 204 abstracts published from 2005 to February 2023, eleven randomised trials involving 2249 patients with a mean age between 43.9 and 56.2 years met the inclusion criteria. All interventions used components of cognitive behavioural therapy. Most studies applied self-guided interventions. Five studies reported percentages of patients never started (range = 3-15%) or discontinued the intervention earlier (range = 3-36%). No long-term effect > 3 months post intervention was reported. Three of seven studies reported a significant short-term intervention effect for distress. Only one study each showed an effect for depression (1/5), anxiety (1/5), fear of recurrence (1/4) and self-efficacy (1/3) compared to a control group. CONCLUSIONS: A wide variance of interventions was used. Future studies should follow guidelines in developing and reporting their mobile interventions and conduct long-term follow-up to achieve reliable and comparable results. IMPLICATIONS FOR CANCER SURVIVORS: No clear effect of psychological mobile health interventions on patients' mental health could be shown. REGISTRATION: PROSPERO ID 312972.

Increased circulating fibronectin, depletion of natural IgM and heightened EBV, HSV-1 reactivation in ME/CFS and long COVID.

Myalgic Encephalomyelitis/ Chronic Fatigue syndrome (ME/CFS) is a complex, debilitating, long-term illness without a diagnostic biomarker. ME/CFS patients share overlapping symptoms with long COVID patients, an observation which has strengthened the infectious origin hypothesis of ME/CFS. However, the exact sequence of events leading to disease development is largely unknown for both clinical conditions. Here we show antibody response to herpesvirus dUTPases, particularly to that of Epstein-Barr virus (EBV) and HSV-1, increased circulating fibronectin (FN1) levels in serum and depletion of natural IgM against fibronectin ((n)IgM-FN1) are common factors for both severe ME/CFS and long COVID. We provide evidence for herpesvirus dUTPases-mediated alterations in host cell cytoskeleton, mitochondrial dysfunction and OXPHOS. Our data show altered active immune complexes, immunoglobulin-mediated mitochondrial fragmentation as well as adaptive IgM production in ME/CFS patients. Our findings provide mechanistic insight into both ME/CFS and long COVID development. Finding of increased circulating FN1 and depletion of (n)IgM-FN1 as a biomarker for the severity of both ME/CFS and long COVID has an immediate implication in diagnostics and development of treatment modalities.

Persistent symptoms and risk factors predicting prolonged time to symptom-free after SARS­CoV­2 infection: an analysis of the baseline examination of the German COVIDOM/NAPKON-POP cohort.

PURPOSE: We aimed to assess symptoms in patients after SARS-CoV-2 infection and to identify factors predicting prolonged time to symptom-free. METHODS: COVIDOM/NAPKON-POP is a population-based prospective cohort of adults whose first on-site visits were scheduled ≥ 6 months after a positive SARS-CoV-2 PCR test. Retrospective data including self-reported symptoms and time to symptom-free were collected during the survey before a site visit. In the survival analyses, being symptom-free served as the event and time to be symptom-free as the time variable. Data were visualized with Kaplan-Meier curves, differences were tested with log-rank tests. A stratified Cox proportional hazard model was used to estimate adjusted hazard ratios (aHRs) of predictors, with aHR < 1 indicating a longer time to symptom-free. RESULTS: Of 1175 symptomatic participants included in the present analysis, 636 (54.1%) reported persistent symptoms after 280 days (SD 68) post infection. 25% of participants were free from symptoms after 18 days [quartiles: 14, 21]. Factors associated with prolonged time to symptom-free were age 49-59 years compared to < 49 years (aHR 0.70, 95% CI 0.56-0.87), female sex (aHR 0.78, 95% CI 0.65-0.93), lower educational level (aHR 0.77, 95% CI 0.64-0.93), living with a partner (aHR 0.81, 95% CI 0.66-0.99), low resilience (aHR 0.65, 95% CI 0.47-0.90), steroid treatment (aHR 0.22, 95% CI 0.05-0.90) and no medication (aHR 0.74, 95% CI 0.62-0.89) during acute infection. CONCLUSION: In the studied population, COVID-19 symptoms had resolved in one-quarter of participants within 18 days, and in 34.5% within 28 days. Over half of the participants reported COVID-19-related symptoms 9 months after infection. Symptom persistence was predominantly determined by participant's characteristics that are difficult to modify.

Prospective single-center study of health-related quality of life after COVID-19 in ICU and non-ICU patients.

Long-term sequelae in hospitalized Coronavirus Disease 2019 (COVID-19) patients may result in limited quality of life. The current study aimed to determine health-related quality of life (HRQoL) after COVID-19 hospitalization in non-intensive care unit (ICU) and ICU patients. This is a single-center study at the University Hospital of Wuerzburg, Germany. Patients eligible were hospitalized with COVID-19 between March 2020 and December 2020. Patients were interviewed 3 and 12 months after hospital discharge. Questionnaires included the European Quality of Life 5 Dimensions 5 Level (EQ-5D-5L), patient health questionnaire-9 (PHQ-9), the generalized anxiety disorder 7 scale (GAD-7), FACIT fatigue scale, perceived stress scale (PSS-10) and posttraumatic symptom scale 10 (PTSS-10). 85 patients were included in the study. The EQ5D-5L-Index significantly differed between non-ICU (0.78 ± 0.33 and 0.84 ± 0.23) and ICU (0.71 ± 0.27; 0.74 ± 0.2) patients after 3- and 12-months. Of non-ICU 87% and 80% of ICU survivors lived at home without support after 12 months. One-third of ICU and half of the non-ICU patients returned to work. A higher percentage of ICU patients was limited in their activities of daily living compared to non-ICU patients. Depression and fatigue were present in one fifth of the ICU patients. Stress levels remained high with only 24% of non-ICU and 3% of ICU patients (p = 0.0186) having low perceived stress. Posttraumatic symptoms were present in 5% of non-ICU and 10% of ICU patients. HRQoL is limited in COVID-19 ICU patients 3- and 12-months post COVID-19 hospitalization, with significantly less improvement at 12-months compared to non-ICU patients. Mental disorders were common highlighting the complexity of post-COVID-19 symptoms as well as the necessity to educate patients and primary care providers about monitoring mental well-being post COVID-19.

Systematic review with meta-analysis: Stress-management interventions for patients with irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a common chronic gastrointestinal disorder of unknown pathological origin that is associated with psychological distress and reduced health-related quality of life (HRQoL). We investigated the effects of stress-management for adults with IBS on typical symptoms, HRQoL and mental health. With predefined criteria (patients: adults with IBS; intervention: stress-management; control: care as usual or waitlist; outcome: patient-relevant; study-type: controlled trials), we registered the study with PROSPERO (168030) and searched the main medical databases. Two researchers independently reviewed the publications and assessed the risk of bias using the Scottish Intercollegiate Guidelines Network checklist. We performed meta-analysis with homogeneous trials of acceptable quality. After screening 6656 publications, ten suitable randomized trials of acceptable (n = 5) or low methodological quality (n = 5) involving 587 patients were identified. Our meta-analysis showed no effect of stress-management on IBS severity 1-2 months after the intervention (Hedges' g = -0.23, 95%-CI = -0.84 to -0.38, I2  = 86.1%), and after 3-12 months (Hedges' g = -0.77, 95%-CI = -1.77 to -0.23, I2  = 93.3%). One trial found a short-term reduction of symptoms, and one trial found symptom relief in the long-term (at 6 months). One of two studies that examined HRQoL found an improvement (after 2 months). One of two studies that examined depression and anxiety found a reduction of these symptoms (after 3 weeks). Stress-management may be beneficial for patients with IBS regarding the short-term reduction of bowel and mental health symptoms, whereas long-term benefits are unclear. Good quality RCTs with more than 6 months follow-up are needed.

A cross-sectional analysis of podiatrist-initiated review processes after issuing prescribed foot orthoses.

BACKGROUND: Foot orthoses are widely used in clinical practice to treat foot, lower limb and back pathology. As published information guiding the clinical use of foot orthoses is scarce, the aim of this study is to profile the review processes used by practicing podiatrists after issuing an orthotic device. METHODS: A cross-sectional observational study design formed the basis for a self-administered online questionnaire. The questionnaire was distributed through podiatry networks based in Australia. RESULTS: Two-hundred and thirty-eight practicing podiatrists participated in this study. Ninety-seven percent of respondents indicated that they would recommend a review appointment after the initial fitting of an orthotic device. Forty percent (n = 84) of respondents scheduled the first review appointment four weeks after the initial fitting, while 33% (n = 69) preferred a two-week review period. A second review consultation was standard practice for 32% (n = 68) or respondents, and were typically scheduled either two (23%, n = 12) or four (38%, n = 20) weeks after the initial review consultation. Annual review of orthotic devices was recommended by 64% (n = 123) of participants in the study, while 19% (n = 37) would suggest that yearly reviews were scheduled only if required. CONCLUSIONS: Variation was identified in the orthotic review processes used by practicing podiatrists, although most respondents recommend a routine short-term review appointment for foot orthoses. It is not clear why practitioners adopt such varied approaches. In the absence of any clear evidence on this topic, it may be that the differing approaches to patient review reflect different philosophical perspectives regarding patient management.

Fatigue and cognitive impairment after COVID-19: A prospective multicentre study.

Background: Reliable estimates of frequency, severity and associated factors of both fatigue and cognitive impairment after COVID-19 are needed. Also, it is not clear whether the two are distinct sequelae of COVID-19 or part of the same syndrome." Methods: In this prospective multicentre study, frequency of post-COVID fatigue and cognitive impairment were assessed in n = 969 patients (535 [55%] female) ≥6 months after SARS-CoV-2 infection with the FACIT-Fatigue scale (cut-off ≤30) and Montreal Cognitive Assessment (≤25 mild, ≤17 moderate impairment) between November 15, 2020 and September 29, 2021 at University Medical Center Schleswig-Holstein, Campus Kiel and University Hospital Würzburg in Germany. 969 matched non-COVID controls were drawn from a pre-pandemic, randomised, Germany-wide population survey which also included the FACIT-Fatigue scale. Associated sociodemographic, comorbid, clinical, psychosocial factors and laboratory markers were identified with univariate and multivariable linear regression models. Findings: On average 9 months after infection, 19% of patients had clinically relevant fatigue, compared to 8% of matched non-COVID controls (p < 0.001). Factors associated with fatigue were female gender, younger age, history of depression and the number of acute COVID symptoms. Among acute COVID symptoms, altered consciousness, dizziness and myalgia were most strongly associated with long-term fatigue. Moreover, 26% of patients had mild and 1% had moderate cognitive impairment. Factors associated with cognitive impairment were older age, male gender, shorter education and a history of neuropsychiatric disease. There was no significant correlation between fatigue and cognitive impairment and only 5% of patients suffered from both conditions. Interpretation: Fatigue and cognitive impairment are two common, but distinct sequelae of COVID-19 with potentially separate pathophysiological pathways. Funding: German Federal Ministry of Education and Research (BMBF).

The German National Pandemic Cohort Network (NAPKON): rationale, study design and baseline characteristics.

The German government initiated the Network University Medicine (NUM) in early 2020 to improve national research activities on the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic. To this end, 36 German Academic Medical Centers started to collaborate on 13 projects, with the largest being the National Pandemic Cohort Network (NAPKON). The NAPKON's goal is creating the most comprehensive Coronavirus Disease 2019 (COVID-19) cohort in Germany. Within NAPKON, adult and pediatric patients are observed in three complementary cohort platforms (Cross-Sectoral, High-Resolution and Population-Based) from the initial infection until up to three years of follow-up. Study procedures comprise comprehensive clinical and imaging diagnostics, quality-of-life assessment, patient-reported outcomes and biosampling. The three cohort platforms build on four infrastructure core units (Interaction, Biosampling, Epidemiology, and Integration) and collaborations with NUM projects. Key components of the data capture, regulatory, and data privacy are based on the German Centre for Cardiovascular Research. By April 01, 2022, 34 university and 40 non-university hospitals have enrolled 5298 patients with local data quality reviews performed on 4727 (89%). 47% were female, the median age was 52 (IQR 36-62-) and 50 pediatric cases were included. 44% of patients were hospitalized, 15% admitted to an intensive care unit, and 12% of patients deceased while enrolled. 8845 visits with biosampling in 4349 patients were conducted by April 03, 2022. In this overview article, we summarize NAPKON's design, relevant milestones including first study population characteristics, and outline the potential of NAPKON for German and international research activities.Trial registration https://clinicaltrials.gov/ct2/show/NCT04768998 . https://clinicaltrials.gov/ct2/show/NCT04747366 . https://clinicaltrials.gov/ct2/show/NCT04679584.

Severity, predictors and clinical correlates of Post-COVID syndrome (PCS) in Germany: A prospective, multi-centre, population-based cohort study.

Background: Post-COVID syndrome (PCS) is an important sequela of COVID-19, characterised by symptom persistence for >3 months, post-acute symptom development, and worsening of pre-existing comorbidities. The causes and public health impact of PCS are still unclear, not least for the lack of efficient means to assess the presence and severity of PCS. Methods: COVIDOM is a population-based cohort study of polymerase chain reaction (PCR) confirmed cases of SARS-CoV-2 infection, recruited through public health authorities in three German regions (Kiel, Berlin, Würzburg) between November 15, 2020 and September 29, 2021. Main inclusion criteria were (i) a PCR confirmed SARS-CoV-2 infection and (ii) a period of at least 6 months between the infection and the visit to the COVIDOM study site. Other inclusion criteria were written informed consent and age ≥18 years. Key exclusion criterion was an acute reinfection with SARS-CoV-2. Study site visits included standardised interviews, in-depth examination, and biomaterial procurement. In sub-cohort Kiel-I, a PCS (severity) score was developed based upon 12 long-term symptom complexes. Two validation sub-cohorts (Würzburg/Berlin, Kiel-II) were used for PCS score replication and identification of clinically meaningful predictors. This study is registered at clinicaltrials.gov (NCT04679584) and at the German Registry for Clinical Studies (DRKS, DRKS00023742). Findings: In Kiel-I (n = 667, 57% women), 90% of participants had received outpatient treatment for acute COVID-19. Neurological ailments (61·5%), fatigue (57·1%), and sleep disturbance (57·0%) were the most frequent persisting symptoms at 6-12 months after infection. Across sub-cohorts (Würzburg/Berlin, n = 316, 52% women; Kiel-II, n = 459, 56% women), higher PCS scores were associated with lower health-related quality of life (EQ-5D-5L-VAS/-index: r = -0·54/ -0·56, all p < 0·0001). Severe, moderate, and mild/no PCS according to the individual participant's PCS score occurred in 18·8%, 48·2%, and 32·9%, respectively, of the Kiel-I sub-cohort. In both validation sub-cohorts, statistically significant predictors of the PCS score included the intensity of acute phase symptoms and the level of personal resilience. Interpretation: PCS severity can be quantified by an easy-to-use symptom-based score reflecting acute phase disease burden and general psychological predisposition. The PCS score thus holds promise to facilitate the clinical diagnosis of PCS, scientific studies of its natural course, and the development of therapeutic interventions. Funding: The COVIDOM study is funded by the Network University Medicine (NUM) as part of the National Pandemic Cohort Network (NAPKON).

The Immune Deficiency and Dysregulation Activity (IDDA2.1 'Kaleidoscope') Score and Other Clinical Measures in Inborn Errors of Immunity.

Quantifying the phenotypic features of rare diseases such as inborn errors of immunity (IEI) helps clinicians make diagnoses, classify disorders, and objectify the disease severity at its first presentation as well as during therapy and follow-up. Furthermore, it may allow cross-sectional and cohort comparisons and support treatment decisions such as an evaluation for transplantation. On the basis of a literature review, we provide a descriptive comparison of ten selected scores and measures frequently used in IEI and divide these into three categories: (1) diagnostic tools (for Hyper-IgE syndrome, hemophagocytic lymphohistiocytosis, and Wiskott-Aldrich syndrome), (2) morbidity and disease activity measures (for common variable immune deficiency [CVID], profound combined immune deficiency, CTLA-4 haploinsufficiency, immune deficiency and dysregulation activity [IDDA], IPEX organ impairment, and the autoinflammatory disease activity index), and (3) treatment stratification scores (shown for hypogammaglobulinemia). The depth of preclinical and statistical validations varies among the presented tools, and disease-inherent and user-dependent factors complicate their broader application. To support a comparable, standardized evaluation for prospective monitoring of diseases with immune dysregulation, we propose the IDDA2.1 score (comprising 22 parameters on a 2-5-step scale) as a simple yet comprehensive and powerful tool. Originally developed for use in a retrospective study in LRBA deficiency, this new version may be applied to all IEI with immune dysregulation. Reviewing published aggregate cohort data from hundreds of patients, the IDDA kaleidoscope function is presented for 18 exemplary IEI as an instructive phenotype-pattern visualization tool, and an unsupervised, hierarchically clustered heatmap mathematically confirms similarities and differences in their phenotype expression profiles.

Coronin7 regulates WASP and SCAR through CRIB mediated interaction with Rac proteins.

Coronin7 (CRN7) stabilizes F-actin and is a regulator of processes associated with the actin cytoskeleton. Its loss leads to defects in phagocytosis, motility and development. It harbors a CRIB (Cdc42- and Rac-interactive binding) domain in each of its WD repeat domains which bind to Rac GTPases preferably in their GDP-loaded forms. Expression of wild type CRN7 in CRN7 deficient cells rescued these defects, whereas proteins with mutations in the CRIB motifs which were associated with altered Rac binding were effective to varying degrees. The presence of one functional CRIB was sufficient to reestablish phagocytosis, cell motility and development. Furthermore, by molecular modeling and mutational analysis we identified the contact regions between CRN7 and the GTPases. We also identified WASP, SCAR and PAKa as downstream effectors in phagocytosis, development and cell surface adhesion, respectively, since ectopic expression rescued these functions.

Influence of casein-phospholipid combinations as emulsifier on the physical and oxidative stability of fish oil-in-water emulsions.

The objective of this study was to investigate the influence of casein (0.3% w/w) and phospholipid (0.5% w/w) emulsifier combinations on the physical and oxidative stability of 10% fish oil-in-water emulsions at pH 7. For that purpose, three phospholipids were evaluated, namely, lecithin (LC), phosphatidylcholine (PC), and phosphatidylethanolamine (PE). The emulsion stabilized with LC showed the best physical stability having the most negative zeta potential and the lowest mean droplet size. In addition, this emulsion was also the least oxidized in terms of peroxide value and concentration of the volatile oxidation product 1-penten-3-ol. This finding is not explained by the antioxidant activity of LC because it showed similar DPPH scavenging activity and lower metal chelating activity than the other phospholipids. Therefore, these results suggested that other factors such as the combination of casein and lecithin, which could result in a favorable structure and thickness of the interfacial layer, prevented lipid oxidation in this emulsion.

Effect of α-lactalbumin and ß-lactoglobulin on the oxidative stability of 10% fish oil-in-water emulsions depends on pH.

The objective of this study was to investigate the influence of pH on lipid oxidation and protein partitioning in 10% fish oil-in-water emulsions prepared with different whey protein isolates with varying ratios of α-lactalbumin and ß-lactoglobulin. Results showed that an increase in pH increased lipid oxidation irrespective of the emulsifier used. At pH 4, lipid oxidation was not affected by the type of whey protein emulsifier used or the partitioning of proteins between the interface and the water phase. However, at pH 7 the emulsifier with the highest concentration of ß-lactoglobulin protected more effectively against oxidation during emulsion production, whereas the emulsions with the highest concentration of α-lactalbumin were most stable to oxidation during storage. These differences were explained by differences in the pressure and adsorption induced unfolding of the individual protein components.

The choice of homogenisation equipment affects lipid oxidation in emulsions.

Milk proteins are often used by the food industry because of their good emulsifying properties. In addition, they can also provide oxidative stability to foods. However, different milk proteins or protein components have been shown to differ in their antioxidative properties, and their localisation in emulsions has been shown to be affected by the emulsification conditions. The objective of this study was to investigate the influence of homogenisation equipment (microfluidizer vs. two-stage valve homogeniser) on lipid oxidation in 10% fish oil-in-water emulsions prepared with two different milk proteins. Emulsions were prepared at pH 7 with similar droplet sizes. Results showed that the oxidative stability of emulsions prepared with sodium caseinate was not influenced by the type of homogeniser used. In contrast, the type of homogenisation equipment significantly influenced lipid oxidation when whey protein was used as emulsifier, with the microfluidizer resulting in lower levels of oxidation.