Combined effect of dynamic heat treatment and ionic strength on denaturation and aggregation of whey proteins – Part I

Nicorescu, I.; Loisel, Catherine; Vial, Christophe; Riaublanc, Alain; Djelveh, Gholamreza; Cuvelier, Gérard; Legrand, Jack

doi:10.1016/j.foodres.2008.05.003

Cited by 44 publications

(30 citation statements)

References 34 publications

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“…This polymodal distribution of unheated WPI dispersions agrees with published literature. In particular, non-aggregated whey proteins, such as lg and lac monomers and dimers, remain below 7 nm (Gimel, Durand, & Nicolai, 1994;Nicorescu et al, 2008;Roefs & De Kruif, 1994); this corresponds to peak 1 distribution observed in unheated WPI. Peak 2 and 3 correspond to native whey aggregates, which are commonly observed in industrial hydrated WPI (Gr' acia-Julia ' et al, 2008;Nicorescu et al, 2008).…”

Section: Whey Protein Aggregationmentioning

confidence: 85%

“…gelation and emulsification) and nutritional properties of whey derivatives (Lefevre, Subirade, & Pezolet, 2005). The effects of heat on denaturation of pure and enriched fractions of -lg has been extensively reported (Nicorescu et al, 2008). It is known that heating at high temperatures (>60 o C) produces thermal denaturation of globular whey proteins.…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have shown that the processes of protein unfolding and aggregation occur to different extents depending on the conditions prevailing in the aqueous solution (e.g. pH, ionic strength, ionic calcium, fat content, presence of lactose and protein composition/concentration), and heating treatments (Anema & Li, 2003;Dalgleish & Banks, 1991;Law & Leaver, 2000;Nicorescu et al, 2008;Verheul, Roefs, & de Kruif, 1998). Ohmic heating (OH) has been receiving increased attention due to its uniform transmission of thermal energy and extremely rapid heating rates that enable high temperatures to be applied without inducing coagulation or excessive denaturation of the constituent proteins (Parrot, 1992).…”

Section: Introductionmentioning

confidence: 99%

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Influence of moderate electric fields on gelation of whey protein isolate

et al. 2015

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Proteins are one of the food constituents most affected by heating, and some of the changes involve their unfolding, denaturation and gelation. Ohmic heating has often been claimed to improve the quality of foodstuffs due to its uniform heating and (putative) presence of a moderate electric field (MEF). However, this is still subject to discussion, so it is important to determine the effect of ohmic heating and of its MEF upon food constituents. Hence, the aim of this work was to evaluate the effects of MEF on denaturation, aggregation and viscoelastic properties of whey protein isolate (WPI), and compare them with those obtained via conventional heating under identical treatment conditions (up to 30 min at 85 o C). Results have shown that MEF interferes with whey protein unfolding and aggregation pathways at relatively high temperatures. MEF treatments have resulted in WPI solutions possessing more 8 and 10% of native Lactoglobulin and Lactalbumin, respectively, after 30 s of heating at 85 o C, when compared with a conventional heating method. Protein aggregates from MEF-treated WPI solutions presented a maximum increase in size of 78 nm, whereas conventional heating produced an increase of 86 nm. Unlike in conventional heating, aggregation of whey proteins during MEF was not sufficiently strong to form a true elastic gel network, since decreases in both storage and loss modulus were observed following MEF treatment. Our results suggest that MEF may provide a novel method for production of a whey protein matrix with distinctive gel-forming properties.2

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Section: Whey Protein Aggregationmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of moderate electric fields on gelation of whey protein isolate

et al. 2015

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“…However, the mechanism of protein unfolding, aggregation, and gelation is rather complex. Gelation depends not only on pH and ionic strength but also on other conditions prevailing in the aqueous solution (i.e., ionic calcium content, fat content, presence of lactose, and protein composition/concentration) and heating treatments (Dalgleish and Banks 1991;Law and Leaver 2000;Nicorescu et al 2008;Tuan et al 2011;Verheul et al 1998;Anema and Li 2003). For instance, it was shown that the type of heating method (direct or indirect) used for protein denaturation should not be overlooked.…”

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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“…Even if heat treatment of whey proteins has been extensively studied, the vast majority of the work is based on static heat treatments in a water bath system, where the time-temperature exposure is very different from the commonly used heat exchangers in dairy industry. Differences between static and dynamic heat treatment are, e.g., in hydrodynamic, mixing and heat transfer conditions (Nicorescu et al, 2008). The industrial aspects of whey protein processing involve dynamic heat treatment, where burning on metal surfaces, drastic viscosity increase and formation of volatile sulphur compounds set the practical limits for concentration and time-temperature exposure used for elimination of microbial activity and efficient protein denaturation.…”

Section: Introductionmentioning

confidence: 99%