Volatiles in diverse, uncharacterized and new long-grain rice varieties

Authors: Beaulieu, John; DUPRE, REBECCA - Orise Fellow; Grimm, Casey; OBANDO-ULLOA, JAVIER - Institute Of Technology; McClung, Anna

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/4/2022
Publication Date: 7/10/2022
Citation: Beaulieu, J.C., Dupre, R.A., Grimm, C.C., Obando-Ulloa, J.M., McClung, A.M. 2022. Volatiles in diverse, uncharacterized and new long-grain rice varieties. Meeting Abstract. 2022;99:985–994.

Interpretive Summary:

Technical Abstract: Introduction: A selection of long-grain rice varieties have been recently characterized as offering health-promoting properties due to high-protein and anthocyanins. However, these varieties have not been characterized for volatiles, which is critical for market acceptance. The most pungent volatile in aromatic rice is 2-acetyl-1-pyrroline, however, there are over 100 volatile compounds reported in rice varieties with pigmented bran. There is interest in developing value added rice products with enhanced nutritional value. Thus, five diverse rice varieties, four of which were previously uncharacterized, were evaluated for volatile compounds to determine differences and trends that may affect flavor. Methods: Rice of four varieties grown in Stuttgart, AR, a commercial paddy and brown rice and purified rice bran were also evaluated. Rough rice samples from AR were freshly processed using Satake Grain Testing Mills and an Udy cyclone mill to produce whole grain kernels, polished white rice, bran, and two flours (white and whole-grain), per variety. Two g dry weight samples were analyzed for volatiles using solid phase microextraction (SPME) on a chilled 4 °C autosampler with GC-MS. Compounds were tentatively identified using the Wiley7th/NIST02 MS library, and validation is in progress using external standards. Results: Reviewing 19 compounds believed to be flavor-important indicated that Tiara (aromatic purple bran) had high levels for five key aroma-impact volatiles known to occur in pigmented bran (heptanal, 2-AP, 2-pentyl furan, benzaldehyde, guaiacol). Tiara and IAC600 (purple) had the highest significant levels of benzothiazole compared to Scarlett (red), and the brown varieties (Cahokia and Rondo). Cahokia displayed the highest significant compound levels reported in the analysis for hexanol, 2-heptanone, 1-heptanol, 1-octen-3-ol, octanal, (E)-2-octenal, 1-octanol, nonanal and total volatiles. Significance: Five diverse rice varieties developed for specialty culinary or nutritional markets were characterized for over 50 volatile compounds. To our knowledge, this is the first GC-MS volatile appraisal in Rondo (used for beverages and flour), Cahokia (a high protein brown rice), and two new USDA pigmented bran rice varieties: Scarlett and Tiara. After establishing volatile baselines, researchers can evaluate the impact of these compounds on organoleptic properties important for value added product development.