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In JoVE (1)
Other Publications (27)
- The Journal of Trauma
- Wall Street Journal (Eastern Ed.)
- Spine
- Journal of Food Science
- Journal of Food Science
- Hip International : the Journal of Clinical and Experimental Research on Hip Pathology and Therapy
- Journal of Magnetic Resonance (San Diego, Calif. : 1997)
- Journal of Food Science
- Journal of Food Science
- Journal of Affective Disorders
- Journal of Psychiatric Research
- Psychopharmacology
- Pharmacogenomics
- Journal of Food Science
- Journal of Food Science
- Journal of Food Science
- Journal of Food Science
- Biotechnology and Bioengineering
- Health & Social Work
- Acta Psychiatrica Scandinavica
- Journal of Circadian Rhythms
- The Journals of Gerontology. Series B, Psychological Sciences and Social Sciences
- Disability and Rehabilitation
- Topics in Stroke Rehabilitation
- Psychopharmacology
- Psychopharmacology
- Journal of Food Science
Articles by Michael J. McCarthy in JoVE
Quantifying Mixing using Magnetic Resonance Imaging
Emilio J. Tozzi1, Kathryn L. McCarthy1, Lori A. Bacca2, William H. Hartt2, Michael J. McCarthy1
1Dept. Food Science and Technology, University of California, Davis, 2Corporate Engineering and Technology Laboratory, Procter & Gamble Company
Magnetic resonance imaging (MRI) provides a powerful tool to evaluate the effectiveness of process equipment during operation. We discuss the use of MRI to visualize mixing in a static mixer. The application is relevant to personal care products, but can be applied to a broad range of food, chemical, biomass and biological fluids.
Other articles by Michael J. McCarthy on PubMed
Assessment of Severity of Ovine Smoke Inhalation Injury by Analysis of Computed Tomographic Scans
The Journal of Trauma. Sep, 2003 | Pubmed ID: 14501881
Our goal was to evaluate computed tomographic (CT) scans of the chest as a means of stratifying smoke inhalation injury (SII) severity.
After Horrific Burn, a Wife's Choice: is Treatment Wise? Artificial Skin for Ted Fink Meant Pain and Risks; a 7-month Induced Coma; 'I Really Didn't Want to Look'
Wall Street Journal (Eastern Ed.). Apr, 2005 | Pubmed ID: 15966124
Cauda Equina Syndrome: Factors Affecting Long-term Functional and Sphincteric Outcome
Spine. Jan, 2007 | Pubmed ID: 17224816
Retrospective cohort study with prospective clinical follow-up.
Magnetic Resonance Temperature Mapping of Microwave-fried Chicken Fingers
Journal of Food Science. Jun, 2009 | Pubmed ID: 19646038
The main objective of this study was to compare the heating patterns of chicken fingers deep-fried conventionally and using a microwave. Two dimensional internal temperature maps of fried chicken fingers with rectangular geometry were measured post frying using magnetic resonance imaging (MRI). Frying was performed in a microwave oven at 365 W power level for 0.5 and 1.5 min after bringing the oil temperature to 180 +/- 1 degrees C. Samples were also fried in a conventional fryer at 180 degrees C for 2 and 5 min for comparison. Variations in internal temperature distribution increased proportionally to frying time in both microwave and conventional frying. Internal thermal equilibrium is reached in all samples after 13 min of holding time. Internal structural changes, void formation, were also visualized in the images. Void formation did not significantly impact cooling rates.
Relationship Between In-line Viscosity and Bostwick Measurement During Ketchup Production
Journal of Food Science. Aug, 2009 | Pubmed ID: 19723191
The Bostwick consistometer remains an integral part of assessing the consistency of tomato products in the factory. This work addresses the blending of tomato pastes, packed at different Bostwick readings, for use in tomato ketchup production. The objective of this study was to correlate in-line viscosity measurements of 12 degrees Bx tomato concentrates to final product quality. Five blends of tomato concentrate were prepared by blending 2 pastes and diluting the mixture to a soluble solids level of 12 degrees Bx. In-line viscometry measurements at process temperature were made using magnetic resonance viscometry. The resulting Herschel-Bulkley parameters were used to evaluate an apparent viscosity at a characteristic shear rate. The apparent viscosity and Bostwick measurement for the blends were correlated based on a gravity current flow analysis, yielding a coefficient of determination of over 0.99. Ketchup was made from the tomato concentrate blends at 3 levels of natural tomato soluble solids (NTSS). The ketchup Bostwick measurement was then correlated to the ratio of (eta/rho)(-1/5) of the 12 degrees Bx tomato concentrate yielding coefficients of determination of 0.97, 0.97, and 0.91 for NTSS levels of 6%, 7%, and 7.8%, respectively. This study demonstrates that final product quality can be predicted from in-line viscosity measurements of an intermediate product.
Two Stage One Component Revision in Infected Total Hip Replacements - Two Case Reports and Literature Review
Hip International : the Journal of Clinical and Experimental Research on Hip Pathology and Therapy. Jul-Sep, 2009 | Pubmed ID: 19876888
We present two cases of infected primary total hip replacements (THR) where only one of the two components exhibited loosening. Both were revised using a two stage, one component revision technique, replacing the loose component only. In the first case the acetabular component was revised leaving the original femoral stem in situ. In the second case, the femoral component was revised, leaving the original acetabular cup undisturbed. Both patients remained infection free at three and half and three years follow up respectively.
L-band Overhauser Dynamic Nuclear Polarization
Journal of Magnetic Resonance (San Diego, Calif. : 1997). Mar, 2010 | Pubmed ID: 20045658
We present the development of an Overhauser dynamic nuclear polarization (DNP) instrument at 0.04 T using 1.1 GHz (L-band) electron spin resonance frequencies (ESR) and 1.7 MHz (1)H nuclear magnetic resonance frequencies. Using this home-built DNP system, the electron-nucleus coupling factor of 4-oxo-TEMPO dissolved in water was determined as 0.39+/-0.06 at 0.04 T. The higher coupling factor obtained at this field compared to higher magnetic fields, such as 0.35 T, directly translates to higher enhancement of the NMR signal and opens up a wider time scale window for observing water dynamics interacting with macromolecular systems, including proteins, polymers or lipid vesicles. The higher enhancements obtained will facilitate the observation of water dynamics at correlation times up to 10 ns, that corresponds to more than one order of magnitude slower dynamics than accessible at 0.35 T using X-band ESR frequencies.
Experimental and Analytical Temperature Distributions During Oven-based Convection Heating
Journal of Food Science. Jan-Feb, 2010 | Pubmed ID: 20492168
Mathematical models, combined with experimental evaluation, provide an approach to understand, design, and optimize food process operations. Magnetic resonance imaging (MRI), as an experimental technique, is used extensively in both medical and engineering applications to measure and quantify transport processes. Magnetic resonance (MR) was used in this study to assess a mathematical model based on Fourier's second law. The objective was to compare analytical solutions for the prediction of internal temperature distributions in foods during oven-based convective heating to experimental temperature measurements and determine at what point during the heating process a coupled heat and mass transport process should be considered. Cylindrical samples of a model food gel, Russet potato and rehydrated mashed potato were heated in a convection oven for specified times. Experimentally measured internal temperatures were compared to the internal temperatures predicted by the analytical model. Temperatures distributions in the axial direction compared favorably for the gel and acceptably for the Russet and mashed potato samples. The MR-acquired temperatures in the radial direction for the gel resulted in a shallower gradient than predicted but followed the expected trend. For the potato samples, the MR-acquired temperatures in the radial direction were not qualitatively similar to the analytical predictions due to moisture loss during heating. If temperature resolution is required in the radial direction, moisture losses merit the use of transport models that couple heat and mass transfer.
Oil Migration in 2-component Confectionery Systems
Journal of Food Science. Jan-Feb, 2010 | Pubmed ID: 20492171
Oil migration from high oil content centers into chocolate coatings results in product quality changes. The objective of this study was to monitor and model peanut oil migration in 2-layer systems of increasing phase complexity. Three 2-layer systems were prepared: peanut oil/cocoa butter; peanut butter paste/cocoa butter; and peanut butter paste/chocolate. Magnetic resonance imaging was used to measure liquid oil signal as a function of position over a storage time of 193 days at 25 degrees C. The 3 types of samples exhibited appreciably different patterns of oil migration. The peanut oil/cocoa butter samples had mass transfer typical of oil being absorbed into a liquid/solid region. The peanut butter paste/cocoa butter magnetic resonance profiles were characterized by mass transfer with a partition coefficient greater than unity. The peanut butter paste/chocolate samples exhibited a time-dependent peanut oil concentration at the interface between the chocolate and peanut butter paste. The spatial and temporal experimental data of the peanut butter paste/chocolate samples were modeled using a Fickian diffusion model, fitting for the effective diffusivity. Values of the diffusivity for the 6 chocolate formulations ranged from 1.10 to 2.01 x 10(-13) m(2)/s, with no statistically significant differences.
Internet Monitoring of Suicide Risk in the Population
Journal of Affective Disorders. May, 2010 | Pubmed ID: 19748681
Public health statistics are often released too late to affect reversible societal factors affecting suicide. Increasingly, internet search volume is used in epidemiology, but this method has not yet been applied to suicide.
Allele Specific Analysis of the ADRBK2 Gene in Lymphoblastoid Cells from Bipolar Disorder Patients
Journal of Psychiatric Research. Mar, 2010 | Pubmed ID: 19766236
G-protein coupled receptor kinase-3 (GRK3), translated from the gene, ADRBK2 has been implicated as a candidate molecule for bipolar disorder through multiple, converging lines of evidence. In some individuals, the ADRBK2 gene harbors the A-haplotype, a collection of single nucleotide polymorphisms (SNPs) previously associated with an increased risk for bipolar disorder. Because the A-haplotype encompasses the ADRBK2 promoter, we hypothesized that it may alter the regulation of gene expression. Using histone H3 acetylation to infer promoter activity in lymphoblastoid cells from patients with bipolar disorder, we examined the A-haplotype within its genomic context and determined that at least four of its SNPs are present in transcriptionally active portions of the promoter. However, using chromatin immunoprecipitation followed by allele-specific PCR in samples heterozygous for the A-haplotype, we found no evidence of altered levels of acetylated histone H3 at the affected allele compared to the common allele. Similarly, using a transcribed SNP to discriminate expressed ADRBK2 mRNA strands by allele of origin; we found that the A-haplotype did not confer an allelic-expression imbalance. Our data suggest that while the A-haplotype is situated in active regulatory sequence, the risk-associated SNPs do not appear to affect ADRBK2 gene regulation at the level of histone H3 acetylation nor do they confer measurable changes in transcription in lymphoblastoid cells. However, tissue-specific mechanisms by which the A-haplotype could affect ADRBK2 in the central nervous system cannot be excluded.
Nicotine Withdrawal and Kappa-opioid Receptors
Psychopharmacology. Jun, 2010 | Pubmed ID: 19806344
The synthesis and release of dynorphin are increased in the caudate/putamen (CPU) and nucleus accumbens (NAc) of nicotine-withdrawn mice, suggesting a role in the nicotine abstinence syndrome.
Pharmacogenetics of Lithium Response in Bipolar Disorder
Pharmacogenomics. Oct, 2010 | Pubmed ID: 21047205
Bipolar disorder (BD) is a serious mental illness with well-established, but poorly characterized genetic risk. Lithium is among the best proven mood stabilizer therapies for BD, but treatment responses vary considerably. Based upon these and other findings, it has been suggested that lithium-responsive BD may be a genetically distinct phenotype within the mood disorder spectrum. This assertion has practical implications both for the treatment of BD and for understanding the neurobiological basis of the illness: genetic variation within lithium-sensitive signaling pathways may confer preferential treatment response, and the involved genes may underlie BD in some individuals. Presently, the mechanism of lithium is reviewed with an emphasis on gene-expression changes in response to lithium. Within this context, findings from genetic-association studies designed to identify lithium response genes in BD patients are evaluated. Finally, a framework is proposed by which future pharmacogenetic studies can incorporate advances in genetics, molecular biology and bioinformatics in a pathway-based approach to predicting lithium treatment response.
Magnetic Resonance Imaging (MRI) and Relaxation Spectrum Analysis As Methods to Investigate Swelling in Whey Protein Gels
Journal of Food Science. Oct, 2010 | Pubmed ID: 21535489
Effective means for controlled delivery of nutrients and nutraceuticals are needed. Whey protein-based gels, as a model system and as a potential delivery system, exhibit pH-dependent swelling when placed in aqueous solutions. Understanding the physics that govern gel swelling is thus important when designing gel-based delivery platforms. The extent of swelling over time was monitored gravimetrically. In addition to gravimetric measurements, magnetic resonance imaging (MRI) a real-time noninvasive imaging technique that quantified changes in geometry and water content of these gels was utilized. Heat-set whey protein gels were prepared at pH 7 and swelling was monitored in aqueous solutions with pH values of 2.5, 7, and 10. Changes in dimension over time, as characterized by the number of voxels in an image, were correlated to gravimetric measurements. Excellent correlations between mass uptake and volume change (R(2)= 0.99) were obtained for the gels in aqueous solutions at pH 7 and 10, but not for gels in the aqueous solution at pH 2.5. To provide insight into the mechanisms for water uptake, nuclear magnetic resonance (NMR) relaxation times were measured in independent experiments. The relaxation spectrum for the spin-spin relaxation time (T(2)) showed the presence of 3 proton pools for pH 7 and 10 trials and 4 proton pools for pH 2.5 trials. Results demonstrate that MRI and NMR relaxation measurements provided information about swelling in whey protein gels that can constitute a new means for investigating and developing effective delivery systems for foods.
¹H-NMR Study of the Impact of High Pressure and Thermal Processing on Cell Membrane Integrity of Onions
Journal of Food Science. Sep, 2010 | Pubmed ID: 21535535
Proton nuclear magnetic resonance (¹H-NMR) relaxometry was used to study the effects of high pressure and thermal processing on membrane permeability and cell compartmentalization, important components of plant tissue texture. High pressure treated onions were subjected to pressure levels from 20 to 200 MPa at 5 min hold time at initial temperatures of 5 and 20 °C. Thermally treated onions were exposed for 30 min at temperatures from 40 to 90 °C. Loss of membrane integrity was clearly shown by changes in transverse relaxation time (T(2)) of water at temperatures of 60 °C and above. Destabilization effects on membranes exposed to high pressure were observed at 200 MPa as indicated by T(2) measurements and cryo-scanning electron microscopy (Cryo-SEM). T(2) relaxation successfully discriminated different degrees of membrane damage based on the T(2) shift of the vacuolar component. Analyses of the average water self-diffusion coefficient indicated less restricted diffusion after membrane rupture occurred in cases of severe thermal treatments. Milder processing treatments yielded lower average diffusion coefficients than the controls. ¹H-NMR proved to be an effective method for quantification of cell membrane damage in onions and allowed for the comparison of different food processes based on their impact on tissue integrity.
Disintegration Efficiency of Pulsed Electric Field Induced Effects on Onion (Allium Cepa L.) Tissues As a Function of Pulse Protocol and Determination of Cell Integrity by ¹H-NMR Relaxometry
Journal of Food Science. Sep, 2010 | Pubmed ID: 21535538
The influence of electrical pulse protocol parameters on cell rupture of onion tissues was investigated in order to improve fundamental understanding and to enhance the processing of plant tissues with pulsed electric fields (PEFs). The impact of PEF parameters on cell integrity of 20 mm dia, 4-mm thick disks of Don Victor onions (Allium cepa L.) was determined by ion leakage measurements. Electric field strength, pulse width, total pulse duration, and frequency effects were determined in relation to their effects on cell damage as a function of pulse protocol. Electric field strengths up to 500 V/cm increased the damage efficiency but there was no significant difference in efficiency beyond this field strength. Larger pulse widths increased the degree of tissue disintegration at a constant pulse number. Higher PEF efficiency was achieved with shorter pulse widths and a larger number of pulses at a constant total treatment time. Lower frequencies caused a greater degree of disintegration at constant number of pulses. ¹H-NMR experiments were performed to determine the proton relaxation components of the PEF-treated onion samples and to obtain cell damage information nondestructively. Paramagnetic ion uptake by the onion sample was used to identify different proton relaxation components. Five different proton relaxation components were observed and changes in the 2 components representing different proton environments showed high correlations with ion leakage results (R²= 0.99), indicating that T(2) distributions can be used to obtain information about cell membrane integrity in PEF-treated samples. 1H-NMR proved to be an effective method for nondestructive quantification of cell membrane rupture in onions.
Image Analysis of Microstructural Changes in Almond Cotyledon As a Result of Processing
Journal of Food Science. Mar, 2011 | Pubmed ID: 21535761
Release of oil from nuts due to damaged cellular structures can degrade the quality of products incorporating nuts. The aim of this study was to investigate the effects of different processing conditions on microstructure of almond tissue and to quantify these changes using image processing. Spinning disk confocal fluorescence microscopy was used for imaging changes in microstructure of almonds as a function of different thermal processing of almonds. Multiple staining of Nile Red and Calcofluor White was applied to differentiate cell wall structures and oil bodies within individual almond cells without chemical fixation. An algorithm for image processing, included image preprocessing, segmentation, and determination of morphological features of segmented objects, was developed. Oil-roasting processes (140 °C and 150 °C) were found to have a significant impact on microstructure of almonds when compared to the hot air-roasting and blanching processes. Oil-roasted almond at 150 °C had a greater cellular damage due to cell wall and membrane rupture. These changes in microstructure of almonds would make them slightly more susceptible to release oil during storage. The image analysis presented allows quantitative evaluation for the effect of different processing on almond microstructure.
Yield Stress of Pretreated Corn Stover Suspensions Using Magnetic Resonance Imaging
Biotechnology and Bioengineering. May, 2011 | Pubmed ID: 21618210
Cellulose fibers in water form networks that give rise to an apparent yield stress, especially at high solids contents. Measuring the yield stress and correlating it with fiber concentration is important for the biomass and pulp industries. Understanding how the yield stress behaves at high solids concentrations is critical to optimize enzymatic hydrolysis of biomass in the production of biofuels. Rheological studies on pretreated corn stover and various pulp fibers have shown that yield stress values correlate with fiber mass concentration through a power-law relationship. We use magnetic resonance imaging (MRI) as an in-line rheometer to measure velocity profiles during pipe flow. If coupled with pressure drop measurements, these allow yield stress values to be determined. We compare our results with literature values and discuss the accuracy and precision of the rheo-MRI measurement, along with the effects of fiber characteristics on the power-law coefficients. Biotechnol. Bioeng. © 2011 Wiley Periodicals, Inc.
Poststroke Depression: Social Workers' Role in Addressing an Underrecognized Psychological Problem for Couples Who Have Experienced Stroke
Health & Social Work. May, 2011 | Pubmed ID: 21661303
Depression is the most common psychological challenge faced by many individuals and families following stroke. Fortunately, poststroke depression is treatable, and even preventable, if social work and other rehabilitation practitioners understand the most common risk factors and become familiar with measures for assessing for depression among patients with medical comorbidities such as stroke.The purpose of this article is to raise awareness among readers about the strong potential for depression following stroke and to provide an overview of common assessment measures. On the basis of increasing numbers of patients being cared for by informal caregivers following discharge from inpatient care facilities, growing evidence of the interconnectedness of couples' emotional well-being and the significance of couples-level factors like relationship quality and coping in the well-being of couples experiencing stroke, and current needs for effective interventions for poststroke depression, a secondary purpose of this article is to describe the importance of assessing and treating survivors in the context of their committed relationships.
The Eyes Are the Window to the Brain: Reviewing Oculomotor Abnormalities in Obsessive-compulsive Disorder
Acta Psychiatrica Scandinavica. Aug, 2011 | Pubmed ID: 21740402
Polymorphisms in Melatonin Synthesis Pathways: Possible Influences on Depression
Journal of Circadian Rhythms. 2011 | Pubmed ID: 21827647
ABSTRACT:
Health Behavior Change Following Chronic Illness in Middle and Later Life
The Journals of Gerontology. Series B, Psychological Sciences and Social Sciences. Oct, 2011 | Pubmed ID: 21983040
Objectives.Understanding lifestyle improvements among individuals with chronic illness is vital for targeting interventions that can increase longevity and improve quality of life. METHODS: Data from the U.S. Health and Retirement Study were used to examine changes in smoking, alcohol use, and exercise 2-14 years after a diagnosis of heart disease, diabetes, cancer, stroke, or lung disease. RESULTS: Patterns of behavior change following diagnosis indicated that the vast majority of individuals diagnosed with a new chronic condition did not adopt healthier behaviors. Smoking cessation among those with heart disease was the largest observed change, but only 40% of smokers quit. There were no significant increases in exercise for any health condition. Changes in alcohol consumption were small, with significant declines in excessive drinking and increases in abstention for a few health conditions. Over the long term, individuals who made changes appeared to maintain those changes. Latent growth curve analyses up to 14 years after diagnosis showed no average long-term improvement in health behaviors.Discussion.Results provide important new information on health behavior changes among those with chronic disease and suggest that intensive efforts are required to help initiate and maintain lifestyle improvements among this population.
Improving the United States Airline Industry's Capacity to Provide Safe and Dignified Services to Travelers with Disabilities: Focus Group Findings
Disability and Rehabilitation. 2011 | Pubmed ID: 22082072
As a component of a training development project for intercity air travel providers, we investigated the capacity of the airline industry to meet the needs of travelers with disabilities by exploring: (1) the level of sensitivity among personnel to travelers' needs, (2) training currently provided, (3) areas in which additional training might be beneficial, and (4) organisational/systems-level commitment to dignified assistance to all travelers.
Expanding Poststroke Depression Research: Movement Toward a Dyadic Perspective
Topics in Stroke Rehabilitation. Sep-Oct, 2011 | Pubmed ID: 22082696
Research on depression following stroke has traditionally been oriented toward understanding the experiences of individual survivors or their spousal caregivers outside of the context of their committed relationship. Moving toward a dyadic orientation to the problem of poststroke depression, in which the stroke survivor-spouse dyad is viewed as the primary unit of analysis, will open the door to new lines of inquiry and may eventually lead to more effective treatments for survivors and their spouses. The first half of this article discusses the rationale for moving poststroke depression research toward a more dyadic perspective and highlights current efforts in this area. The second half of this article discusses some methodological challenges associated with dyadic data and the practical benefits of one statistical methodology, multilevel modeling, for examining depression in survivor-stroke dyads.
CREB Involvement in the Regulation of Striatal Prodynorphin by Nicotine
Psychopharmacology. Nov, 2011 | Pubmed ID: 22086359
RATIONALE: The transcription factor cAMP response element binding (CREB) protein plays a pivotal role in drug-dependent neuronal plasticity. CREB phosphorylation at Ser133 is enhanced by drugs of abuse, including nicotine. Dynorphin (Dyn) contributes to the addictive process and its precursor gene prodynorphin (PD) is regulated by CREB. PD mRNA and Dyn synthesis were enhanced in the striatum following acute nicotine, suggesting genomic regulation. OBJECTIVE: These studies investigated PD transcription in mice acutely treated with nicotine, determined the role of CREB, and characterized the receptors involved. RESULTS: Acute nicotine increased adenylyl cyclase activity, cAMP, and pCREB Ser133 levels in striatum and enhanced CREB binding to CRE elements (DynCREs) of the PD promoter, preferentially DynCRE3. DynCRE3 binding was dose dependent with 1 mg of nicotine giving a maximal response. Additionally, DynCRE binding was time dependent, rising by 15 min, reaching a maximum at 1 h, and returning to control by 3 h, a temporal pattern similar to that of cAMP and pCREB. Supershift experiments showed that CREB and pCREB Ser133 were the major contributors to DynCRE3 binding complex. The nAChR antagonist mecamylamine and the dopamine D1-like receptor antagonist SCH 23390 prevented the nicotine-induced increase of pCREB and nuclear protein binding to DynCRE3. CONCLUSIONS: Our findings suggest that nicotine regulates PD expression in striatum at the transcriptional level and CREB is involved. Dopamine D1 receptor stimulation by nAChR-released dopamine appears to be an underlying mechanism. Altered Dyn synthesis might be relevant for the behavioral actions of nicotine and especially its aversive properties.
Desensitization of δ-opioid Receptors in Nucleus Accumbens During Nicotine Withdrawal
Psychopharmacology. Feb, 2011 | Pubmed ID: 20941594
The synthesis and release of met-enkephalin and β-endorphin, endogenous ligands for δ-opioid peptide receptors (DOPrs), are altered following nicotine administration and may play a role in nicotine addiction.
Uptake of Divalent Ions (Mn(+2) and Ca(+2) ) by Heat-Set Whey Protein Gels
Journal of Food Science. Jan, 2012 | Pubmed ID: 22251393
Divalent salts are used commonly for gelation of polymer molecules. Calcium, Ca(+2) , is one of the most common divalent ions that is used in whey protein gels. Manganese, Mn(+2) , is also divalent, but paramagnetic, enhancing relaxation decay rates in magnetic resonance imaging (MRI) and can be used as a probe to understand the behavior of Ca(+2) in whey protein gels. The objective of this study was to investigate the diffusion of Ca(+2) and Mn(+2) ions in heat-set whey protein gels by using MRI and nuclear magnetic resonance (NMR) relaxometry. Whey protein gels were immersed in solutions containing MnCl(2) and CaCl(2) at neutral pH. Images obtained with gels immersed in MnCl(2) solution revealed a relaxation sink region in the gel's surface and the thickness of the region increased with time. These "no signal" regions in the MR images were attributed to uptake of Mn(+2) by the gel. Results obtained with CaCl(2) solution indicated that since Ca(+2) did not have the paramagnetic effect, the regions where Ca(+2) diffused into the gel exhibited a slight decrease in signal intensity. The relaxation spectrums exhibited 3 populations of protons, for gels immersed in MnCl(2) solution, and 2 populations for gels in CaCl(2) solution. No significant change in T(2) distributions was observed for the gels immersed in CaCl(2) solution. The results demonstrated that MRI and NMR relaxometry can be used to understand the diffusion of ions into the whey protein gel, which is useful for designing gels of different physical properties for controlled release applications. Practical Application: Design of food systems for delivery of bioactive compounds requires knowledge of diffusion rates and structure. Utilizing magnetic resonance imaging the diffusion rates of ions can be measured. Relaxation spectra could yield information concerning molecular interactions.
