In this brief article, we will answer the question, “does neem oil go bad?”, and will tell you how long neem oil lasts and how you can extend its shelf life by storing it properly.
Does Neem Oil Go Bad?
Yes, Neem oil does go bad. Oils of vegetal origin undergoes oxidative degradation over time due to the significant amount of fatty acids with double bonds present in it (1).
Nem oil will lose its potency with time, so you should check the expiration date before you buy it.
Generally, an unopened bottle of neem oil will last around a year if stored properly. If it is refrigerated, it can last longer. An opened bottle of neem oil, if stored in a cool, dark place, can last for as long as two years.
How Long Does Neem Oil Last?
As mentioned, a new bottle of neem oil has a shelf life of around one year. In some cases, there is no expiry date mentioned on the label, so make sure you note the time when you open and start using the bottle so you can make an estimate. Contact with ambient air, exposure to sunlight, contact with metals, and exposure to high temperature conditions accelerate the oxidation reactions leading to lower oxidation stability of this oil (1).
While the consistency and constituency of every neem product are different, here are some general guidelines about storing different forms of neem oil to retain their quality for extended periods.
Neem Oil Concentrate
Neem kernels contain 30 – 50% oil and many active ingredients having antifeedant, growth-inhibiting, antiviral activity and anti-ovipositional properties. Neem oil is widely used as insecticides, lubricant, drugs for a variety of diseases such as diabetes and tuberculosis. Average percent of fatty acid content was oleic acid 45.6%, linoleic acid 16.8%, palmitic acid 17.21%, stearic acid 15.2% and linolenic acid 1.3% (3).
Neem oil concentrate needs special care and goes bad very quickly, especially if stored improperly. It must be refrigerated to prolong its shelf life. Neem kernel extract can be prepared and stored in the dark at least 5 mo until it is needed (2).
Cooled neem oil doesn’t support bacterial growth and the ingredients don’t separate, which keeps it good for a long time. However, a study showed that neem extract stored for a short period at high temperatures (50 °C for 2 wk) did not reduce neem kernel extract effectiveness compared with neem kernel extract storage at 5 or 28 °C (2).
Neem Oil Extract
Neem oil extract is similar to neem oil; it must be stored at a low temperature to prolong its shelf life. A good practice is to seal the bottle carefully after every use and keep it refrigerated.
Neem Oil Spray
Unlike the types mentioned above, neem oil spray can last for a long time, given that it is stored properly.
Again, store it at low temperatures, but do not refrigerate it. Simply keep it in a cool place away from humidity and exposure to direct heat.
Mixed Neem Oil
Mixed neem oil also goes bad relatively soon. This is because when neem oil is mixed with water, it begins to break down rather quickly. The presence of water leads to hydrolysis or hydrolytic oxidation (4).
Hence, you should only mix the amount of oil you need and use it quickly. It is recommended that you use all mixed solutions within four to six hours of preparation for best results. It can be effective for up to 3-4 days (6).
How To Store Neem Oil
Neem oil contains unsaturated fatty acids. Instability Is greatly exacerbated if two or more carbon double bonds represent fatty acid chains, so that more highly unsaturated fatty acid chains are relatively less stable. In the process of oxidative degradation, unsaturated sites afat acid chain undergo free radical attack; where a hydrogen atom is abstracted from the fatty acid chain (4). Contact with ambient air, exposure to sunlight, contact with metals, and exposure to high temperature conditions accelerate the oxidation reactions (1). Here are some tips to properly store neem oil:.
- Pure neem oil can retain its potency at temperatures of about 40 to 44 degrees Celsius. Keep it out of light and do not break the seal on the bottle till you need to use it.
- Remember that neem oil is a pesticide, so always store it away from food products. Also, store in dark glass bottles and mix some dish soap in the solutions for best results.
- If you’re planning to use neem oil immediately or within a few days, you can store it at room temperature in a cool, dry place, such as a pantry, away from moisture, humidity, and direct sunlight. In these conditions, neem oil will last for about a week.
- To further extend the shelf life of neem oil further, keep it in the refrigerator; it will last for about two to three years.years past its expiry date. The cooler the oil, the longer it lasts.
- Neem oil hardens at colder temperatures (below 77 degrees Fahrenheit), so you’ll need to leave it at room temperature for some time before using it. Alternatively, you can scoop out the amount you need and add it to your solution.
- Buy only cold-pressed neem oil. As compared to hot-pressed oils, cold-pressed oils retain their natural properties during and after production, hence being more beneficial and effective. Also, cold-pressed oils retain their original potency for longer periods.
Can You Freeze Neem Oil?
No, freezing neem oil is not recommended.
Since the best way to increase the shelf life of neem oil is to keep it cool, most people assume that storing a bottle of neem oil in the freezer will extend its shelf life for years. However, this is not the case.
Freezing, thawing, and refreezing neem oil leaves a thick, black deposit at the bottom of the bottle known as stearin. The latter indicates that the oil has lost most of its potency. Fatty acids undergo oxidation processes to a greater extent during repeated freeze-thaw cycles (5).
If you have a frozen bottle of neem oil, thaw it slowly at room temperature and do not refreeze it. You can also soften it by putting the bottle in lukewarm water. Just don’t heat it since this also compromises its quality.
In this brief article, we will answer the question, “does neem oil go bad?”and will tell you how long neem oil lasts and how you can extend its shelf life by storing it properly.
If you have any questions or comments please let us know.
- Balaji, G., and M. Cheralathan. The effect of antioxidant additives with methyl ester of neem oil on the oxidation stability. Energy Sour A, 2016, 38, 2454-2461.
- Jenkins, David A., Florence V. Dunkel, and Kadiatou Toure Gamby. Storage temperature of neem kernel extract: differential effects on oviposition deterrency and larval toxicity of Callosobruchus maculatus (F.)(Coleoptera: Bruchidae). Environ Entom, 2003, 32, 1283-1289.
- Ali, Rehab Farouk M., and Ayman M. El-Anany. Stabilization of neem oil biodiesel with corn silk extract during long-term storage. J Oleo Sci, 2017. ess16146.
- Pullen, James, and Khizer Saeed. An overview of biodiesel oxidation stability. Renew Sust Energy Rev, 2012, 16, 5924-5950.
- Rahman, M. H., et al. Evaluation of physicochemical deterioration and lipid oxidation of beef muscle affected by freeze-thaw cycles. Kor j food sci an res, 2015, 35, 772.
- Thomas, J. How long does neem oil last? A complete shelf life guide. Backyard garden geek.