High-quality Italian rice cultivars: Chemical indices of ageing and aroma quality

The volatile fractions of six Italian high-quality rice cultivars were investigated by HS-SPME-GC-MS to define fingerprinting and identify chemical markers and/or indices of ageing and aroma quality. In particular, four non-aromatic (Carnaroli, Carnise, Cerere and Antares) and two aromatic (Apollo and Venere) rices, harvested in 2010 and 2011, were monitored over 12 months. Twenty five aroma components were considered and, despite considerable inter-annual variability, some of them showed similar trends over time, including 2-(E)-octenal as a marker of ageing for all cultivars, and heptanal, octanal and 2-ethyl hexanol as cultivar-specific indicators. The area ratios 2-acetyl-1-pyrroline/1-octen-3-ol, for Venere, and 3-methyl-1-butanol/2-methyl-1-butanol, for Apollo, were also found to act as ageing indices. Additional information on release of key-aroma compounds was also obtained from quantitation and its dependence on grain shape and chemical composition. Heptanal/1-octen-3-ol and heptanal/octanal ratios were also defined as characterizing the aroma quality indices of the six Italian rice cultivars investigated.