My grapefruit juice often smells like rotting eggs. Why?
According to:
http://www.confex.com/ift/98annual/accepted/867.htm
http://www.lal.ufl.edu/rouseff/Abstract1.htm#abstract5
Grapefruit juice contains a wide variety of organic sulfur compounds such as p-menthene-8-thiol and 4-methyl-4-mercapto-2-pentanone. What a charming name !
Some of these sulfur compounds are both volatile and extremely smelly, so you’ll notice them if you sniff the container. Apparently the amount of sulfur compounds increases dramatically if the juice has been heated, so your nose may be telling you that your juice was mistreated somewhere between the tree and your refrigerator.