(AP) -- Phil DeVore pulls a folded piece of aluminum from a murky pond. The aluminum looks like a piece of siding that's blown off a building, but DeVore knows it's much more valuable than that. He slips a rubber band off the aluminum and unfolds it. He likes what he sees -- 50 or 60 glistening black leeches. They're your common ribbon leeches, Nephelopsis obscura to aquatic biologists.
After its initial use, cooking oil can be refrigerated or frozen and reused for another six hours of cooking (see References 2). Don't reuse cooking oil if it smells rancid or you can't heat it without smoke developing, as this indicates significant deterioration (see References 1 and 4).
Shelf life of sesame oil. It has been studied and stated that the storage duration of sesame seed oil is six months. It is hard to tell whether the oil became rancid by tasting it only, as the taste does not differ much. However, Ehow has some tips on finding out whether the oil went rancid, like heating it in order to determine the rancidity through scent.