Fresh eggs have a mild flavor that has proven difficult to analyze. The white contributes the main sulfury note, the yolk a sweet, buttery quality. The aroma produced by a given egg is slightest immediately after laying, and gets stronger the longer it’s stored before cooking. In general, egg age and storage conditions have a greater influence on flavor than the hen’s diet and freedom to range. However, both diet and pedigree can have noticeable effects. Brown-egg breeds are unable to metabolize an odorless component of rapeseed and soy meals (choline), and their intestinal microbes then transform it into a fishy-tasting molecule (triethylamine) that ends up in the eggs. Fish-meal feeds and certain feed pesticides cause off-flavors. The unpredictable diet of truly free-range hens will produce unpredictable eggs.