The Chinese, like the inhabitants of the South of Europe, seem to attach a higher value on oils, in proportion as age has given to them a higher degree of Rancidity.
"Travels in China, Containing Descriptions, Observations, and Comparisons, Made and Collected in the Course of a Short Residence at the Imperial Palace of Yuen-Min-Yuen, and on a Subsequent Journey through the Country from Pekin to Canton"
John Barrow
In either case, keep now-opened, in-use small bottles of oil in the refrigerator because Rancidity is simply the combination of oil with oxygen from the air and this chemical reaction is accelerated at warmer temperatures and slowed greatly at cold ones.
"How and When to Be Your Own Doctor"
Dr. Isabelle A. Moser with Steve Solomon
The French often add to it, after it has been melted, a piece of toasted bread, which helps to destroy the tendency of the batter to Rancidity.
"The Book of Household Management"
Mrs. Isabella Beeton