Effects of sprouting and fermentation on the formation of Maillard reaction products in different cereals heated as wholemeal

The concentration and composition of reducing sugars and free amino acids as Maillard reaction (MR) precursors change with grain sprouting. The formation of early and advanced glycation products, and alpha-dicarbonyl compounds as intermediates were monitored during heating native and sprouted wholemeals, as well as during heating of yeast and sourdough fermented native and sprouted wholemeals. Sprouting increased the concentration of all MR products because of an increase in reducing sugar concentrations. Although reducing sugars were lowered due to their consumption by yeasts, fermentation did not lower the furosine concentration. Sourdough fermentation unexpectedly increased furosine because the low pH caused glucose release from polysaccharides. Glyoxal, methylglyoxal and diacetyl were found to be formed as metabolites during yeast and sourdough fermentation. Another factor affecting the MR in sprouted/fermented wholemeals was revealed to be the increased amount of total free amino acids that compete with bound lysine to react with reducing sugars.

Automated summary

The concentration and composition of reducing sugars and free amino acids change with grain sprouting, affecting the Maillard reaction. Sprouting increases the concentration of Maillard reaction products due to the increase in reducing sugar concentration. Fermentation lowers reducing sugar concentration but does not decrease furosine concentration. Surprisingly, sourdough fermentation increases furosine due to glucose release from polysaccharides at low pH. Metabolites such as glyoxal, methylglyoxal, and diacetyl are formed during yeast and sourdough fermentation. Another factor affecting the Maillard reaction in sprouted/fermented wholemeals is the increased amount of total free amino acids that compete with bound lysine to react with reducing sugars.