scholarly journals Optimisation and comparison of orthogonal methods for separation and characterisation of extracellular vesicles to investigate how representative infant milk formula is of milk

2020 ◽  
Author(s):  
Anindya Mukhopadhya ◽  
Jessie Santoro ◽  
Barry Moran ◽  
Zivile Useckaite ◽  
Lorraine O’Driscoll
Keyword(s):  
Extracellular Vesicles ◽  
Skim Milk ◽  
Milk Formula ◽  
Casein Micelles ◽  
Imaging Flow Cytometry ◽  
Infant Milk Formula ◽  
Transmission Electron ◽  
Sds Page ◽  
Orthogonal Methods ◽  
Pre Treatment

AbstractThis study aimed to separate and characterise extracellular vesicles (EV) from infant milk formula (IMF) and skim milk (SM), to determine how representative the EV content of IMF is to SM. Contaminant casein micelles, due to their abundance and overlapping size, were removed followed by either differential ultracentrifugation (DUC) or gradient ultracentrifugation (GUC). Characterisation included BCA, SDS-PAGE, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), immunoblotting, and imaging flow cytometry (IFCM). NTA reported significantly reduced concentrations of EVs/particles in IMF versus SM; TEM showed intact SM-derived EVs to sparse and disrupted EV-like structures in IMF. Compared to IMF, noticeably stronger bands for EV biomarkers were observed by immunoblotting in SM, indicating compromised EV proteins in IMF; also supported by IFCM. Altogether, we established that EVs are substantially compromised during IMF processing. Furthermore, an optimised method combining acid pre-treatment and GUC for EV separation from milk products has been established.

Changes in Size of Casein Micelles Caused by Growth of Psychrotrophic Bacteria in Raw Skim Milk

1984 ◽  
Vol 47 (1) ◽  
pp. 16-19 ◽  
Author(s):  
JONATHAN P. BURLINGAME-FREY ◽  
ELMER H. MARTH
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Skim Milk ◽  
Bacterial Activity ◽  
Casein Micelles ◽  
Psychrotrophic Bacteria ◽  
Ph Values ◽  
Psychrotrophic Bacterium ◽  
Transmission Electron

Raw skim milk was inoculated (1%, v/v) with a proteolytic psychrotrophic bacterium that previously was isolated from milk. The inoculated skim milk was incubated at 7°C for 0, 3, 5 and 7 d. The pH values for the milk were 6.6, 6.5, 6.45 and 5.95, and the numbers of psychrotrophs/ml were 1.0 × 104 8.9 × 107, 9.0 × 108 and 2.5 × 108 for days 0, 3, 5 and 7, respectively. Samples of milk were negatively stained, examined with transmission electron microscopy and distribution of sizes of casein micelles was determined. The average and (mode) sizes of micelles were 849 (789), 1030 (634), 761 (634) and 405 (316) Angstroms for milks after days 0, 3, 5 and 7, respectively. Another set of samples was prepared from skim milk immediately after it was acidified to pH values of 6.6, 6.5, 6.45 and 5.95. The average and (mode) sizes of micelles were 891 (766), 875 (615), 913 (766) and 840 (615) Angstroms for milks having pH values of 6.6, 6.5, 6.45 and 5.95, respectively. Changes in size of micelles in the incubated samples resulted from bacterial activity other than small changes in pH.

Real-Time Monitoring of Luciferase-Tagged Cronobacter sakazakii in Reconstituted Infant Milk Formula

2011 ◽  
Vol 74 (4) ◽  
pp. 573-579 ◽  
Author(s):  
RUTH MORRISSEY ◽  
MÁIRE BEGLEY ◽  
SATORU OSHIMA ◽  
MARY REA ◽  
R. PAUL ROSS ◽  
...  
Keyword(s):  
Real Time ◽  
High Throughput ◽  
Skim Milk ◽  
Luria Bertani ◽  
Milk Formula ◽  
Cronobacter Sakazakii ◽  
Real Time Monitoring ◽  
Luria Bertani Broth ◽  
Infant Milk Formula

The aim of this study was to examine the potential of using a lux-tagged Cronobacter sakazakii strain to monitor growth of the bacterium in various liquids. C. sakazakii was transformed with plasmid p16Slux, and integration of the plasmid at the desired site on the chromosome was confirmed by PCR. The growth of the lux-tagged strain was similar to that of the non–lux-tagged strain, and the integrated plasmid was stable when cells were cultured in the absence of antibiotic. Growth of the lux-tagged strain was monitored in real time in Luria-Bertani broth, skim milk, and infant milk formula by using both the Luminoskan luminometer and the Xenogen IVIS imager. Bioluminescence could be detected when the lux-tagged strain was cocultured with other bacteria. The effect of monocaprylin and nisin on the growth of C. sakazakii in milk was monitored by measuring bioluminescence. In conclusion, growth of a lux-tagged C. sakazakii can be monitored in real time in both clear and opaque liquids by measuring bioluminescence. lux-tagged C. sakazakii strains could be potentially used in high-throughput assays to monitor the effects of various infant milk formula compositions on growth of the bacterium.

scholarly journals Influence of Chymosin on Physicochemical and Hydrolysis Characteristics of Casein Micelles and Individual Caseins

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2594
Author(s):  
Chun-Chi Chen ◽  
Liang-Yu Chen ◽  
Wen-Tai Li ◽  
Ken-Lin Chang ◽  
Meng-I Kuo ◽  
...  
Keyword(s):  
Particle Size ◽  
Incubation Period ◽  
Skim Milk ◽  
Particle Size Analysis ◽  
Supernatant Fraction ◽  
Size Analysis ◽  
Casein Micelles ◽  
Molecular Weights ◽  
Sds Page ◽  
Β Lactoglobulin

The effects of chymosin on the physicochemical and hydrolysis characteristics of casein micelles and individual caseins were investigated. Adding 0.03 units of chymosin/mL led to the casein micelles in skim milk coagulating after a 3 h incubation period at 30 °C. SDS–PAGE investigation showed that β-CN, κ-CN, αs-CN, and a portion of β-lactoglobulin (β-LG) in the milk supernatant fraction (MSF) were precipitated into the milk pellet fraction (MPF). The mean particle size of the MSF with chymosin decreased from 254.4 nm to 179.2 nm after a 3 h incubation period. Mass spectrometry and SDS–PAGE analysis suggested that chymosin hydrolyzed individual β-CN, κ-CN, and αs-CN, but not β-LG. Chymosin hydrolysis led to a decrease in the molecular weights of the hydrolyzed β-CN, κ-CN, and αs-CN. Particle size analysis indicated that there was no difference in the particle size distribution of hydrolyzed β-CN and αs-CN. Moreover, our outcomes demonstrated that the hydrolysis of κ-CN by chymosin occurs before that of β-CN and αs-CN.

Milk gel Structure: II. Relation between firmness and ultrastructure of heat-induced skim-milk gels containing 40–60% total solids

1974 ◽  
Vol 41 (1) ◽  
pp. 131-135 ◽  
Author(s):  
Miloslav Kalab ◽  
V. R. Harwalkar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Skim Milk ◽  
Close Correlation ◽  
Gel Structure ◽  
Casein Micelles ◽  
Ammonium Persulphate ◽  
Total Solids ◽  
Transmission Electron

SummaryMilk gels varying widely in firmness were examined by both scanning and transmission electron microscopy, and a close correlation was found between their ultrastructure and firmness. In gels containing 40 and 50% total solids (14 and 17% protein respectively), casein micelles appeared as individual entities linked by some bridging material. At 60% total solids (20% protein), the micelles were fused and offered a considerably higher resistance to a penetrometer probe. Likewise some additives to gels, such as ammonium persulphate and CaCl2, caused the micelles to fuse. These chemicals appreciably increased firmness of such gels. In gels containing hexametaphosphate, a known inhibitor of gelation, most of the casein micelles were disintegrated; these gels were soft.

Pilot-scale ceramic membrane filtration of skim milk for the production of a protein base ingredient for use in infant milk formula

2017 ◽  
Vol 73 ◽  
pp. 57-62 ◽  
Author(s):  
Noel A. McCarthy ◽  
Heni B. Wijayanti ◽  
Shane V. Crowley ◽  
James A. O'Mahony ◽  
Mark A. Fenelon
Keyword(s):  
Membrane Filtration ◽  
Ceramic Membrane ◽  
Skim Milk ◽  
Pilot Scale ◽  
Milk Formula ◽  
Infant Milk Formula

Effect of high hydrostatic pressure and whey proteins on the disruption of casein micelle isolates

2007 ◽  
Vol 74 (4) ◽  
pp. 452-458 ◽  
Author(s):  
Federico M Harte ◽  
Subba Rao Gurram ◽  
Lloyd O Luedecke ◽  
Barry G Swanson ◽  
Gustavo V Barbosa-Cánovas
Keyword(s):  
Hydrostatic Pressure ◽  
Whey Protein ◽  
High Hydrostatic Pressure ◽  
Analytical Ultracentrifugation ◽  
Whey Proteins ◽  
Skim Milk ◽  
Casein Micelle ◽  
Casein Micelles ◽  
Transmission Electron ◽  
Thermally Processed

High hydrostatic pressure disruption of casein micelle isolates was studied by analytical ultracentrifugation and transmission electron microscopy. Casein micelles were isolated from skim milk and subjected to combinations of thermal treatment (85°C, 20 min) and high hydrostatic pressure (up to 676 MPa) with and without whey protein added. High hydrostatic pressure promoted extensive disruption of the casein micelles in the 250 to 310 MPa pressure range. At pressures greater than 310 MPa no further disruption was observed. The addition of whey protein to casein micelle isolates protected the micelles from high hydrostatic pressure induced disruption only when the mix was thermally processed before pressure treatment. The more whey protein was added (up to 5 g/l) the more the protection against high hydrostatic pressure induced micelle disruption was observed in thermally treated samples subjected to 310 MPa.

EELS characterization of “Smut” layer films on steel surface prepared for chrome plating by anodic etching

1995 ◽  
Vol 53 ◽  
pp. 538-539
Author(s):  
E Y. Wang ◽  
J. T. Cherian ◽  
A. Madsen ◽  
R. M. Fisher
Keyword(s):  
Steel Surface ◽  
Surface Preparation ◽  
Treatment Method ◽  
Chrome Plating ◽  
Transmission Electron ◽  
Alloy Steels ◽  
Pre Treatment ◽  
Hard Chrome ◽  
Electron Energy Loss

Many steel parts are electro-plated with chromium to protect them against corrosion and to improve their wear-resistance. Good adhesion of the chrome plate to the steel surface, which is essential for long term durability of the part, is extremely dependent on surface preparation prior to plating. Recently, McDonnell Douglas developed a new pre-treatment method for chrome plating in which the steel is anodically etched in a sulfuric acid and hydrofluoric acid solution. On carbon steel surfaces, this anodic pre-treatment produces a dark, loosely adhering material that is commonly called the “smut” layer. On stainless steels and nickel alloys, the surface is only darkened by the anodic pre-treatment and little residue is produced. Anodic pre-treatment prior to hard chrome plating results in much better adherence to both carbon and alloy steels.We have characterized the anodic pre-treated steel surface and the resulting “smut” layer using various techniques including electron spectroscopy for chemical analysis (ESCA) on bulk samples and transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) on stripped films.

On Feasibility of Adapted Goat Infant Milk Formula Usage in Newborns with Perinatal Pathology

2017 ◽  
pp. 91-94
Author(s):  
T.M. Klymenko ◽  
◽  
O.A. Serdtseva ◽  
O.S. Karatai ◽  
O.P. Melnychuk ◽  
...  
Keyword(s):  
Milk Formula ◽  
Perinatal Pathology ◽  
Infant Milk Formula
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