Challenges of developing a valid Dietary Glucosinolate database

Authors: Wu, Xianli; Sun, Jianghao; Haytowitz, David; Harnly, James - Jim; Chen, Pei; Pehrsson, Pamela

Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2017
Publication Date: 7/11/2017
Citation: Wu, X., Sun, J., Haytowitz, D.B., Harnly, J.M., Chen, P., Pehrsson, P.R. 2017. Challenges of developing a valid Dietary Glucosinolate database. Journal of Food Composition and Analysis. https://doi.org/10.1016/j.jfca.2017.07.014.
DOI: https://doi.org/10.1016/j.jfca.2017.07.014

Interpretive Summary: Glucosinolates are a group of important sulfur-containing compounds found in cruciferous vegetables. They have been suggested to be the major cancer chemo-preventive agents in these vegetables. To estimate the dietary intake of this group of compounds and evaluate their health impact, there is a great need to develop a valid dietary glucosinolate database. Three challenges were discussed in developing valid dietary glucosinolates database. Sample preparation is the first challenge for accurate analysis. Enzyme deactivation was shown to be a necessary step to preserve glucosinolate. Among three different methods, steaming and microwaving were found to effectively deactivate enzyme. However, enzyme deactivation also also altered the glucosinolate profiles. The second challenge is the analytical method. The methods that measure individual glucosinolates and isothiocyanates, including those measuring intact glucosinolates and desulfated glucosinolates, are considered acceptable methods for database development. The third challenge is what to measure and present in the database. It was proposed that the intact glucosinolates and their bioactive breakdown compounds should be analyzed in processed samples and be presented in the database. In conclusion, the sample preparation procedure, analytical method for quantification and the compounds to be measured must be considered and validated in order to develop a valid dietary glucosinolate database.

Technical Abstract: Glucosinolates are a group of important sulfur-containing compounds found in cruciferous vegetables. They have been suggested to be the major cancer chemo-preventive agents in these vegetables. To estimate the dietary intake of this group of compounds and evaluate their health impact, there is a great need to develop a valid dietary glucosinolate database. Glucosinolates co-exist with the indigenous enzyme myrosinase in plant. Upon cell rupture, the glucosinolates come in contact with myrosinase, which leads to the cleavage of glucose and formation of a number of breakdown compounds. Sample preparation is the first challenge for accurate analysis. Enzyme deactivation was shown to be a necessary step to preserve glucosinolate, which is extremely critical for certain vegetables such as kale. Among three different methods, steaming and microwaving were found to effectively deactivate myrosinase. However, enzyme deactivation also inevitably altered the glucosinolate profiles. The second challenge is the analytical method. While measuring intact glucosinolates remains a difficult task, the current methods involve multi-step sample preparation resulting in great variation among different analyzers. The methods that measure individual glucosinolates and isothiocyanates, including those measuring intact glucosinolates and desulfated glucosinolates, are considered acceptable methods for database development. Considering the fact that actual bioactive compounds in human body are isothiocyanates, the third challenge is what to measure and present in the database. Processed samples with common processing and cooking methods should be used in the analysis; and both glucosinolates and isothiocyanate should be analyzed in processed samples and be presented in the database. In conclusion, the sample preparation procedure, analytical method for quantification and the compounds to be measured must be considered and validated in order to develop a valid dietary glucosinolate database.