Influence of Na+, K+ and Ca2+ on mechanical and structural properties of gels from chestnut and rice flours

The addition of salts to foodstuffs to improve the mechanical characteristics and thereby increasing sample strength has been widely studied in gels of model systems, however has been investigated to a lesser extent in complex systems, such as gluten-free flour gels. The objective of this study was to evaluate the impact of cation concentration and ion valence of chloride salts (NaCl, KCl or CaCl2, 0-2%, w/w) on textural, rheological and microstructural properties of selected gluten-free flour gels from blends of chestnut flour and whole, Agulha or Carolino rice flours. Firmness increased in the presence of CaCl2. Storage and loss moduli increased slightly with the monovalent salts concentration, whereas a more pronounced rise was observed with the divalent salt addition. It was found that K+ was more effective in modifying the rheology of studied gels than Na+. Confocal microscopic images of gels revealed a microstructure consistent with the observed mechanical properties.