What is a defining characteristic of washed-rind cheeses?

Washed-rind cheeses are characterized by their unique aging process, which involves the regular washing of the cheese rind, often with a brine solution or other liquids. This practice encourages the development of specific microbial life, particularly bacteria and yeasts, that contribute to the distinctive flavor and aroma of the cheese. The washing removes surface mold and alters the environment on the rind, which helps in forming that characteristic sticky, orange, or reddish hue typical of these cheeses.

The other choices do not accurately describe washed-rind cheeses. While some washed-rind cheeses may have a softer, less stable outer rind due to the washing process, they do not necessarily have a hard outer rind. Additionally, washed-rind cheeses can be made from a variety of milk types, including cow, goat, and sheep milk, so saying they are made exclusively from goat milk is incorrect. Finally, while lactic acid fermentation is a commonality in many cheeses, washed-rind cheeses involve a mix of bacteria that create diverse flavors, rather than being fermented with lactic acid only.