Submitted to: Sensing and Instrumentation for Food Quality and Safety
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/27/2012
Publication Date: 2/22/2012
Publication URL: handle.nal.usda.gov/10113/58011
Citation: Bryant, R.J., McClung, A.M., Grimm, C.C. 2012. Development of a single kernel analysis method for detection of 2-acetyl-1-pyrroline in aromatic rice germplasm. Sensing and Instrumentation for Food Quality and Safety. 5::147-154. Interpretive Summary: The market is increasing for aromatic rice varieties which possess the 2-acetyl-1-pyrroline (2-AP) compound which gives the grain a popcorn or nutty natural flavor. Rice breeders desire to develop improved aromatic cultivars having high yield and milling quality. To do this, there is a need to have an efficient method of detecting non-aromatic rice from aromatic rice. This study demonstrates a method that can utilize just a single kernel to detect the 2-AP compound. The method will be useful to researchers in identifying aromatic kernels from no-aromatic kernels; to breeders in developing new aromatic cultivars; and, to representatives of the rice industry interested in identifying possible adulteration of aromatic rice products with non-aromatic rice.
Technical Abstract: Solid-phase microextraction (SPME) in conjunction with GC/MS was used to distinguish non-aromatic rice (Oryza sativa, L.) kernels from aromatic rice kernels. In this method, single kernels along with 10 µl of 0.1 ng 2,4,6-Trimethylpyridine (TMP) were placed in sealed vials and heated to 80oC for 18 min. During the heating stage volatile compounds, which include 2-acetyl-1-pyrroline (2-AP), were adsorbed onto a SPME fiber. Volatiles were desorbed from the fiber and separated using gas chromatography. 2-AP was quantitated by mass spectrometry using the 111 m/z, 83 m/z and 68 m/z ions. The method was successful in detecting 2-AP in milled rice and brown rice; however, its detection in paddy rice was less successful. In a mixture of aromatic and non-aromatic rice, the aromatic rice kernels were differentiated from the non-aromatic rice kernels using the described method. Therefore, this method can be used to select individual aromatic progeny from a segregating cross or check for adulteration of expensive aromatic rice with inexpensive non-aromatic rice.