Chemometric Approach for Discriminating the Volatile Profile of Cooked Glutinous and Normal-Amylose Rice Cultivars...

Area of Science:

• Food Chemistry
• Analytical Chemistry
• Plant Science

Background:

• Consumer preference for cooked rice is strongly influenced by its aroma.
• Previous research on rice aroma volatiles was limited by analytical techniques, hindering differentiation between rice types.

Purpose of the Study:

• To comprehensively profile and compare the volatile compounds responsible for the distinct aromas of glutinous and normal-amylose japonica rice.
• To identify novel aroma compounds and establish molecular markers for flavor-based rice breeding.

Main Methods:

• Headspace volatiles from cooked glutinous and normal japonica rice cultivars were captured using MonoTrap.
• Volatile compounds were analyzed using comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC × GC-TOFMS).
• Chemometric analyses, including hierarchical clustering, Principal Component Analysis (PCA), and volcano plots, were employed for data interpretation.

Main Results:

• The GC × GC-TOFMS platform identified 1924 volatile peaks, a ten-fold increase over previous studies, enabling clear separation of rice starch classes.
• Volcano plots identified 277 compounds enriched in glutinous rice and 295 in normal Koshihikari rice, with 270 compounds newly documented in rice.
• Normal rice volatiles (ethers, aldehydes, amines) contributed to grainy, grassy, and toasty notes, while glutinous rice volatiles (ketones, furans, acids, thiols) imparted sweeter, fruitier, and floral notes.

Conclusions:

• This study significantly expands the known volatile chemical library for japonica rice.
• The identified volatile profiles serve as molecular markers for breeding rice cultivars with targeted flavor profiles.
• Comprehensive GC × GC-TOFMS coupled with chemometrics is a powerful approach for detailed grain aroma research.