Electric fields (EF) technologies have been establishing a solid position in emergent food processing and have seen as serious alternatives to traditional thermal processing. During the last decades, research has been devoted to elucidation of technological and safety issues but also fundamental aspects related with interaction of electric fields (EF) with important macromolecules, such as proteins. Proteins are building blocks for the development of functional networks that can encompass health benefits (i.e. nutritional and bioactive properties) but may be also linked with adverse effects such as neurodegenerative diseases (amyloid fibrils) and immunological responses. The biological function of a protein depends on its tridimensional structure/conformation, and latest research evidences that EF can promote disturbances on protein conformation, change their unfolding mechanisms, aggregation and interaction patterns. This review aims at bringing together these recent findings as well as providing novel perspectives about how EF can shape the behavior of proteins towards the development of innovative foods, aiming at consumers' health and wellbeing.

Whey protein gelation and final gel properties are dependent of the gel forming solution characteristics (e.g. protein concentration, pH, ionic strength), and physical variables involved in the method used for gel preparation. Ohmic heating (OH) is an emerging technology in food processing and its application in heat-induced gelation of whey proteins has demonstrated its capacity to influence the physicochemical properties of protein gels. In this work, we studied the OH process and its inherent moderate electric field (MEF) variables-i.e. electric field (EF) strength and frequency-in order to establish their influence in protein aggregation and gelation during WPI cold-set gels formation. The presence of the EF during OH, particularly at higher EF strengths conjugated with lower frequencies, contributed to the formation of smaller aggregates with lower content of reactive thiol groups and lower viscosity. The cold-set gels produced from the aggregates' suspension presented distinctive properties, influenced by the EF variables.-i.e. higher EF strength and lower frequency. EF treatments give rise to more fine-stranded gels with lower disulphide crosslinking but higher number of hydrophobic interactions and hydrogen bonds. The EF effects during the treatments resulted in weaker, more elastic gels with higher water retention and swelling capacity. These results open novel perspectives for the use of OH as a tool for fine-tuning protein gel networks aiming at enhanced functionality for various applications (e.g. use as texturizer or encapsulating agents).

Background: Plant proteins possess promising technological-functional properties that can be used for the development of innovative protein systems. Following the global requirements of environmentally friendly politics, "green" and cost-effective processing technologies, such as ohmic heating and high pressure processing are of great interest. These technologies have demonstrated their potential to modify protein structure and therefore their function, opening interesting possibilities for the design of functional food systems. However, these innovations must also include nutritional and health/wellness aspects, such as the interaction with other food components, and the behavior in the gastrointestinal tract (digestibility and bioavailability). Scope and approach: This review addresses the most promising technological-functional attributes of plant proteins, as well as considerations and strategies needed for the development of innovative food systems. New insights will also be provided on how emerging processing technologies such as ohmic heating and high pressure processing can affect the behavior of proteins. The processing effects in proteins' structure and in their technological-functional properties and ultimately in the biofunctional and nutritional aspects of foods made therefrom will be critically discussed. Key findings and conclusions: Fundamental research regarding the relationship between structural modifications and functionality of more conventional proteins is still required. Furthermore, additional research is necessary on proteins from less studied sources, highlighting those displaying both functional and quality parameters of interest. Emergent processing technologies can help guaranteeing the quality and preservation of foods, as well as act as effective tools to develop technological-functional attributes of food proteins ensuring nutritional and health/wellness aspects.

In this study, the effects of moderate electric fields during thermal denaturation of β-lactoglobulin were examined through an in situ circular dichroism approach, complemented by intrinsic extrinsic fluorescence analysis. Results have shown that the effects of electric fields in protein unfolding were linearly dependent on the applied electric field intensity (V/cm) and increased by the use of low electric frequenciesi.e. 50 to 200 Hz. These electric effects caused significant changes on β-lactoglobulin melting temperature, unfolded conformation and subsequent intermolecular interactions, revealed by the increase of surface hydrophobicity (ANS affinity) and higher conservation of retinol binding. The obtained data provides a clear evidence that moderate electric fields contribute to distinct folding/unfolding of β-lactoglobulin, resulting in structural modifications. These findings are relevant for (bio)-technological applications involving electric fields processing, bringing new insights for the development of innovative strategies to control protein function and tune production of functional protein systems.

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