The shelf life if krill oil is significantly longer than fish oil. Fish oil, like many oils, can turn rancid very quickly and always needs to be refrigerated. Krill oil however, does not need turn rancid even at room temperature and is just as beneficial after more than two years.
Why Does Krill Oil Have a Longer Shelf Life than Fish Oil?
Oils turn rancid because of oxidation. Oils contain double bonds. Monounsaturated and polyunsaturated fats are more susceptible to oxygen attacking their bonds since they are missing several pairs of hydrogen atoms. It is very harmful to eat rancid oils because they contain free radicals that are known to be carcinogenic and related to the onset of many other dysfunctions. You just don’t want to be eating rancid oils.
There is a test to measure the oxidation in fresh oils called the Peroxide Value Test. Any value more than 2 is an indicator that that oil will turn rancid while on the shelf. The Peroxide Value of krill oil is very low—0.5 which ensures a long shelf life. Why is the Peroxide Value of krill oil low even though it is a polyunsaturated oil? The answer lies in the Oil Stability Index of krill oil.
Oil Stability Index (OSI) is another method used to measure the resistance of oils to oxidation. It is the point in time till which the oil is stable. After this point the oil begins to oxidize at an accelerated rate. A number of factors affect the OSI of oils: degree of saturation, natural or added antioxidants or prior abuse. In krill oil, the antioxidants astaxanthin and the flavonoid in it, esterify with a double bond with EPA and DHA respectively. This is one of the major reasons why krill oil has a long shelf life. Therefore the OSI of krill oil is that its peroxide value (rancidity potential) remains less than 0.5 for over 50 hours at 97.8 degrees C (208 F).
So at room temperature, krill oil can stay fresh and ready to use for over two years. So you don’t have to worry about consuming rotten oils or reordering fresh stock every few months. krill oil has the same benefits whether consumed on the day it was extracted or two years from the manufacturing date.