The amount of sulfenic acids and lacrimal factor released and the irritation effect differs among "Allium" species. In 2008, the New Zealand Institute for Crop and Food Research created "no tears" onions by genetic modification to prevent the synthesis of lachrymatory factor synthase in onions. One study suggests that consumers prefer the flavor of onions with lower LFS content. However, since the LFS-silencing process involves reducing sulfur ingestion by the plant, it has also been suggested that LFS− onions are inferior in flavor. A method for efficiently differentiating LFS− and LFS+ onions has been developed based on mass spectrometry, with potential application in high-volume production; gas chromatography is also used to measure lachrymatory factor in onions. In early 2018, Bayer released the first crop yield of commercially available LFS-silenced onions under the name "Sunions." They were the product of 30 years of cross-breeding; genetic modification was not employed.