I worked for a snack foods mfr about 15 yrs ago. They used partially
hydrogenated vegetable oil to fry the pork rinds. They used the same oil
every day and added fresh oil to bring the fatty acids up to an acceptable
level.(They break down after being heated so many times). After so many
batches were cooked, they threw this oil out and refilled the fryer with
completely fresh oil. As far as I know this practice is still current.