Accelerated solvent extraction of alkylresorcinols in food products containing uncooked and cooked wheat

Authors: HOLT, MONTE - University Of Sciences - Philadelphia; Moreau, Robert; DERMARDEROSIAN, ARA - University Of Sciences - Philadelphia; MCKEOWN, NICOLA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; JACQUES, PAUL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2012
Publication Date: 4/24/2012
Citation: Holt, M.D., Moreau, R.A., Dermarderosian, A., Mckeown, N., Jacques, P.F. 2012. Accelerated solvent extraction of alkylresorcinols in food products containing uncooked and cooked wheat. Journal of Agricultural and Food Chemistry. 60(19):4799-4802.

Interpretive Summary: Alkylresorcinols (AR) are lipids (fats) that are present in high amounts in the outer bran layer of wheat and rye. This outer bran layer is removed during the refining process, thus AR are largely present in whole grains but present in much smaller amounts in refined grains. AR are of interest in nutrition research because the amount of AR present in an individual’s blood or urine may represent the amount of whole grains they have consumed. Most research examining whole grain intake relies on individuals to self-report the amount of whole grains they have eaten. This can be inaccurate since it is particularly difficult for even well-informed consumers to identify which foods are whole grain versus not and also to quantify amounts eaten. Measuring AR content through a urine or blood collection, rather than through self-report, could improve accuracy in quantifying whole grain intake. However, in order to interpret AR amounts present in human blood or urine, we need to measure the amount of AR in actual foods themselves. This involves identifying the optimal method for extracting AR from foods. The purpose of this study was to determine the best method of extracting AR from both cooked and uncooked foods. We extracted AR from unprocessed wheat bran and the following processed foods: whole grain cereal, refined grain cereal, whole wheat bread, refined grain bread, whole grain crackers, refined grain crackers, whole wheat pasta, refined grain pasta, and whole wheat flour. We extracted AR from these foods using a previously established, manual extraction method, as well as a method called rapid accelerated solvent extraction (ASE). ASE is a semi-automated technique currently accepted by the U.S. Environmental Protection Agency that utilizes higher temperatures and pressures during the extraction process. Higher pressures allow for solvents to be heated at temperatures higher than their normal boiling point, resulting in fast, efficient extractions. Automation of the system also reduces analyst time. Results from this study indicated that ASE can be comparable to current extraction methods. Furthermore, the extraction time for ASE (approx. 40 minutes) is much more convenient, less tedious, and less time-consuming than previously established methods, which range from 5 hours for processed foods to 24 hours for raw grains.

Technical Abstract: This research focuses on the overall extraction process of alkylresorcinols (ARs) from uncooked grains and baked products that have been processed with wheat, corn, rice, and white flour. Previously established extraction methods developed by Ross and colleagues, as well as a semiautomated method involving accelerated solvent extraction (ASE), were applied to extract ARs within freshly ground samples. For extraction of alkylresorcinols, nonpolar solvents such as ethyl acetate have been recommended for the extraction of uncooked foods, and polar solvents such as 1-propanol:water (3:1 v/v) have been recommended for the extraction of baked foods that contain rye, wheat, or other starch-rich grains. A comparison of AR extraction methods has been investigated with the application of gas chromatography and a flame ionization detector (GC-FID) to quantify the AR content. The goal of this research was to compare the rapid accelerated solvent extraction of the alkylresorcinols (ASE-AR) method to the previous manual AR extraction methods. Results for this study as well as the investigation of the overall efficiency of ASE-AR extraction with the use of a spiking study indicated that it can be comparable to current extraction methods but with less time required. Furthermore, the extraction time for ASE (approximately 40 min) is much more convenient and less tedious and time-consuming than previously established methods, which range from 5 h for processed foods to 24 h for raw grains.