Lactic acid (lactate)

Once again, I stand corrected: The Vegan Society has a list of potentially non-vegan ingredients. Their website also has a lot of other useful resources. 

Keep in mind the word "potential:" a lot of these ingredients can come from both animal and non-animal sources. For example, lactic acid (lactate) is listed as derived form milk, whether other sources claim is is most often vegan:

Quote:

"If it's lactate or lactic acid, it's not from dairy (exception - sterol lactate due to the stearic acid). "Lac" ingredients are usually produced by a fermentation process using cornstarch or beet sugar. Lactose is always from dairy."

Source: http://www.vrg.org/nutshell/faqingredients.htm#lac

Wikipedia article says that although it can be produced from lactose, it usually comes from bacterial culture.