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

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 approximate to 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 rice in methylene chloride held at 85 degrees C far 2.5 hr. The complete gas chromatographic run requires approximate to 25 min, and 50 samples can be analyzed per day. The optimized method's linear response (R(2) = 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.