Rapid gas chromatographic technique for quantifying 2-acetyl-1-pyrroline and hexanal in rice (Oryza sativa, L.)

C. J. Bergman, J. T. Delgado, R. Bryant, C. Grimm, K. R. Cadwallader, B. D. Webb

Research output: Contribution to journalArticlepeer-review


The aroma of rice plays a role in its consumer acceptability. The popcorn-like smell of aromatic rice stemming primarily from its 2-acetyl-1- pyrroline (2-AP) content is considered desirable by many consumers. Conversely, hexanal has been correlated with off odors in rice that develop from lipid oxidation. A rapid method for 2-AP and hexanal quantification suitable for use in breeding programs, large-scale research efforts, and quality assurance programs is needed. While developing such a method, sample preparation (degree of milling, particle size), solvent extraction time and temperature, and gas chromatographic parameters were studied. Particle size had no influence on 2-AP or hexanal recovered. One extraction solubilized ≃80% of the 2-AP and 56% of the hexanal present in milled rice. The optimum extraction method was assessed to require 0.3 g of ground brown or milled flee in methylene chloride held at 85°C for 2.5 hr. The complete gas chromatographic run requires ≃25 min, and 50 samples can be analyzed per day. The optimized method's linear response (R2 = 0.99) and reproducibility was demonstrated. The stability of 2-AP and hexanal in frozen milled rice and in refrigerated methylene chloride extracts was excellent for at least six months. Milled and unmilled commercial and breeders' aromatic rice samples contained 10-1,104 ng/g of 2-AP and 148-2,541 ng/g of hexanal. Genotype had the greatest effect on the 2-AP and hexanal content of two lines grown over four years and in four states.

Original languageEnglish (US)
Pages (from-to)454-458
Number of pages5
JournalCereal Chemistry
Issue number4
StatePublished - Jan 1 2000
Externally publishedYes

ASJC Scopus subject areas

  • Food Science
  • Organic Chemistry

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