Raman characterization of the interactions between gliadins and anthocyanins

Abstract

Gliadins, the major proteins of the wheat flour, are a family of monomeric and disulphide‐bonded proteins formed by a non‐repetitive domain rich in α‐helix structures and heterogeneous repetitive domains rich in β‐reverse turns. Gliadins may be strong food allergens, and many studies have explored the mechanisms of gluten allergenicity, with the final aim to properly modify gluten proteins in order to decrease allergen immunoreactivity. In the present study, Raman spectroscopy was used to gain more insights into the conformational changes of gliadins upon interaction with different anthocyanins (kuromanin, callistephin, oenin, cyanin, pelargonin, malvin). Anthocyanins are powerful antioxidant molecules with anti‐carcinogenic properties and largely widespread natural colorants present in vegetables and flowers. Raman spectroscopy demonstrated that the anthocyanins under study induce in gliadins conformational changes of different extents. The treatment with malvin, kuromanin and callistephin induced significant changes in the tyrosine environment, while pelargonin, oenin and cyanin did not. The treatment with any of the anthocyanins altered the distribution of the disulphide conformations: the gauche‐gauche‐trans conformation increased at the expenses of the gauche‐gauche‐gauche conformation. Malvin and pelargonin provoked a significant decrease of the β‐turns content. Since both the latter structural elements have been related to gluten allergenicity, anthocyanins appeared interesting molecules, in the context of the attempts to modify gliadins with the aim to decrease allergen immunoreactivity. Copyright © 2013 John Wiley & Sons, Ltd.

Raman studies of gluten proteins aggregation induced by dietary fibres

“…The decrease in the tyrosine doublet ratio can be also connected with the anthocyanin content. A similar decrease in the ratio value was observed by Taddei et al (2013), who studied the interactions between gliadins and anthocyanins. Although cranberry fibre contains a similar amount of anthocyanins as cacao fibre, the value of I(850)/I(830) increases with increasing fibre content.…”

Influence of dietary fibre on gluten proteins structure – a study on model flour with application of FT‐Raman spectroscopy

“…The authors postulated that small molecules of phenolic acids were incorporated into protein network, allowing proteins to aggregate and strengthen the dough. Studies of interactions between gliadins and different anthocyanins showed that they caused decrease in amount of unordered structures contrary to polyphenols . However, anthocyanins induced also forming of new hydrogen bonds, which led to folding or aggregation of the proteins.…”

Identification of anthocyanins in plant sources and textiles by surface-enhanced Raman spectroscopy (SERS)

“…Anthocyanins have recently attracted the interest of many researchers mainly due to their possible use as food colorants, and to their antioxidant properties, being very effective scavengers of free radicals, but also thanks to their capacity to decrease allergen immunoreactivity . However, the colors of flowers and fruits have fascinated the humankind since ancient times: the use of anthocyanins as dyeing matter is reported in the Roman period by Pliny the Elder and the famous architect Vitruvius .…”