Fine-Stranded and Particulate Aggregates of Heat-Denatured Whey Proteins Visualized by Atomic Force Microscopy

Ikeda, Shinya; Morris, Victor J.

doi:10.1021/bm0156429

Cited by 191 publications

(186 citation statements)

References 46 publications

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“…Fig. 4 shows globular microstructure of the pure WPI as reported previously in the literature (Ikeda & Morris, 2002). The local aggregations in the pure WPI may be a result of the heat denaturation of proteins.…”

Section: Morphological Propertiessupporting

confidence: 63%

Improvement of barrier and mechanical properties of whey protein isolate based food packaging films by incorporation of zein nanoparticles as a novel bionanocomposite

2016

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a b s t r a c tIn this study, whey protein isolate (WPI) based bio-nanocomposite films embedded with zein nanoparticles (ZNP) were prepared by solution casting. Nanoparticles were coated with sodium caseinate to obtain a uniform distribution in the films. The mechanical, water vapor barrier, surface wetting, morphological and viscoelastic properties of the films were investigated. The addition of ZNP significantly improved the water vapor barrier and mechanical properties of the WPI without adversely affecting the elongation of the films. Dynamical mechanical analysis and contact angle measurements revealed that upon addition of the nanoparticles, the fractional free volume and hydrophilicity of the WPI films decreased. Sodium caseinate containing both hydrophilic and hydrophobic groups created an efficient interface between the hydrophobic ZNP and hydrophilic WPI matrix, allowing for a homogeneous distribution of nanoparticles even at very high loading levels as evidenced by the scanning electron microscope (SEM) and atomic force microscopy (AFM) images. The WPI/ZNP nanocomposite films can potentially become effective food packaging materials.

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Section: Morphological Propertiessupporting

confidence: 63%

Improvement of barrier and mechanical properties of whey protein isolate based food packaging films by incorporation of zein nanoparticles as a novel bionanocomposite

2016

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“…WPI, due mostly to the presence of β-lactoglobulin (β-lg), can form particulate networks in the pH range of 4-6, while fine-stranded networks are formed above and below this region (Stading et al 1992;Ikeda and Morris 2002;Nicolai et al 2011). Production and development of β-lg and WPI hydrogels have been studied extensively during the latest de-cades (Bryant and McClements 1998;Kavanagh et al 2000;Lefevre and Subirade 2000;Phan-Xuan et al 2013;Hermansson 1990, 1991;Stading et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Production of Whey Protein-Based Aggregates Under Ohmic Heating

Pereira

Rodrigues

Ramos

et al. 2015

Food Bioprocess Technol

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Formation of whey protein isolate protein aggregates under the influence of moderate electric fields upon ohmic heating (OH) has been monitored through evaluation of molecular protein unfolding, loss of its solubility, and aggregation. To shed more light on the microstructure of the protein aggregates produced by OH, samples were assayed by transmission electron microscopy (TEM). Results show that during early steps of an OH thermal treatment, aggregation of whey proteins can be reduced with a concomitant reduction of the heating charge-by reducing the comeup time (CUT) needed to reach a target temperature-and increase of the electric field applied (from 6 to 12 V cm −1 ). Exposure of reactive free thiol groups involved in molecular unfolding of β-lactoglobulin (β-lg) can be reduced from 10 to 20 %, when a CUT of 10 s is combined with an electric field of 12 V cm −1 .Kinetic and multivariate analysis evidenced that the presence of an electric field during heating contributes to a change in the amplitude of aggregation, as well as in the shape of the produced aggregates. TEM discloses the appearance of small fibrillar aggregates upon the influence of OH, which have recognized potential in the functionalization of food protein networks. This study demonstrated that OH technology can be used to tailor denaturation and aggregation behavior of whey proteins due to the presence of a constant electric field together with the ability to provide a very fast heating, thus overcoming heat transfer limitations that naturally occur during conventional thermal treatments.

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“…Studies devoted to the characterization of fibril structures based on light, neutrons and X-ray scattering methods, being bulk techniques, have only provided an average ensemble picture of the fibrils 23 . Single-molecule techniques such as atomic force microscopy (AFM) and transmission electron microscopy (TEM) have recently emerged to probe amyloid fibrils at the molecular level [24][25][26][27] . Nevertheless, so far, a fully comprehensive picture of the aggregation behaviour among different amyloid fibrils has not yet been achieved.…”

mentioning

confidence: 99%

Understanding amyloid aggregation by statistical analysis of atomic force microscopy images

et al. 2010

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The aggregation of proteins is central to many aspects of daily life, including food processing, blood coagulation, eye cataract formation disease and prion-related neurodegenerative infections [1][2][3][4][5] . However, the physical mechanisms responsible for amyloidosis-the irreversible fibril formation of various proteins that is linked to disorders such as Alzheimer's, Creutzfeldt-Jakob and Huntington's diseases-have not yet been fully elucidated [6][7][8][9] . Here, we show that different stages of amyloid aggregation can be examined by performing a statistical polymer physics analysis of single-molecule atomic force microscopy images of heat-denatured b-lactoglobulin fibrils. The atomic force microscopy analysis, supported by theoretical arguments, reveals that the fibrils have a multistranded helical shape with twisted ribbon-like structures. Our results also indicate a possible general model for amyloid fibril assembly and illustrate the potential of this approach for investigating fibrillar systems.Protein self-assembly is a wide-ranging phenomenon and is of great importance in several areas of science. The reversible formation of fibrils from globular proteins is a phenomenon occurring naturally, in vivo, for proteins such as actin and tubulin 10,11 . Other well-known examples of protein fibrillation include the irreversible amyloid fibril formation of various proteins implicated in neurological disorders such as Alzheimer's, Creutzfeldt-Jakob or Huntington's diseases. Typically, these fibrils have long, unbranched, and often twisted structures that are a few nanometres in diameter 1,8 . However, many peptides and proteins, including many globular food proteins that are used as gelling agents, foaming agents or emulsifiers, can also form amyloid-like structures in vitro. Such structures can possess desirable mechanical properties and can be used to create useful textures and structures 12,13 .An example of a fibril formation of globular proteins is provided by the fine-stranded heat-set gels formed by heating solutions of various globular food proteins such as ovalbumin, bovine serum albumin 12 and b-lactoglobulin 13 . b-Lactoglobulin has been particularly well studied, because it represents both a relevant model system and a major whey protein of interest to the food industry [14][15][16][17][18][19][20][21][22] .Despite the fact that the individual parameters controlling the aggregation of globular proteins into amyloid fibrils have been well identified, the driving force for such an aggregation process still remains obscure. Studies devoted to the characterization of fibril structures based on light, neutrons and X-ray scattering methods, being bulk techniques, have only provided an average ensemble picture of the fibrils 23 . Single-molecule techniques such as atomic force microscopy (AFM) and transmission electron microscopy (TEM) have recently emerged to probe amyloid fibrils at the molecular level [24][25][26][27] . Nevertheless, so far, a fully comprehensive picture of the aggregation behaviour...

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Fine-Stranded and Particulate Aggregates of Heat-Denatured Whey Proteins Visualized by Atomic Force Microscopy

Cited by 191 publications

References 46 publications

Improvement of barrier and mechanical properties of whey protein isolate based food packaging films by incorporation of zein nanoparticles as a novel bionanocomposite

Improvement of barrier and mechanical properties of whey protein isolate based food packaging films by incorporation of zein nanoparticles as a novel bionanocomposite

Production of Whey Protein-Based Aggregates Under Ohmic Heating

Understanding amyloid aggregation by statistical analysis of atomic force microscopy images

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