Advances on analytical methods for pea protein structure characterization

The growing world's population and the awareness of consumers about their health and the environment increased the demand of plant-based proteins. Pea proteins are gaining popularity due to their wide availability, high nutritional value, non-GMO status, low allergenicity and low cost. Pea protein has attracted attention as a functional ingredient, but its application is still limited compared with soy protein due to inadequate research. Indeed, Functional properties of proteins are based mainly on their structure and ability to interact with other food materials. Understanding the changes in pea protein structure as a function of environmental and processing conditions or interactions with other materials is fundamental to facilitate the utilisation of pea proteins in various applications. Elucidation of the structure of pea proteins involves the use of techniques like: i) mass spectrometry to study their primary structure, ii) optical methods such as spectroscopy including mid-infrared, fluorescence and nuclear magnetic resonance spectroscopy to investigate the secondary, tertiary structure and the dynamics of pea protein, iii) microscopy imaging techniques such as and scanning electron microscopy to explore the microstructure of pea proteins, iv) X-ray methods such as X-ray diffraction, X-ray microtomography and small-angle X-ray scattering to study the physicochemical attributes (amorphous/crystalline) of pea proteins and v) calorimetric methods such as differential scanning calorimetry to deliver information about their conformational changes and thermal properties. This review provides an overview of common analytical techniques suitable for characterizing the structure of pea protein in its different organization levels, providing structural, and conformational information, as well as insights into dynamics.