Palm oil has become a prevalent ingredient in many food products due to its versatility and low cost. However, there are concerns that the widespread use of palm oil may have negative health and environmental impacts. One potential benefit of palm oil that manufacturers often cite is its ability to extend the shelf life of foods. But does scientific evidence support the claim that palm oil can significantly prolong shelf life compared to other oils?
What is palm oil?
Palm oil is edible vegetable oil that comes from the fruit of oil palm trees. Palm trees are native to Africa but are now grown across tropical regions of Asia, Africa, and the Americas. The oil is extracted from the fleshy fruit of oil palms through pressing and processing.
Palm oil is semi-solid at room temperature due to its high percentage of saturated fat. The main saturated fats in palm oil are palmitic acid and stearic acid. Palm oil also contains monounsaturated and polyunsaturated fats including oleic acid and linoleic acid.
Why is palm oil used in food production?
Palm oil has some properties that make it attractive for use in processed foods and consumer products:
– High yield – Oil palm trees produce more oil per land area compared to other vegetable oil crops. This makes palm oil very efficient and economical.
– Versatile – With its semi-solid room temperature state, palm oil can be used as a replacement for partially hydrogenated oils. This allows texture and consistency modification in products.
– Heat stability – Due to its high saturated fat content, palm oil is resistant to oxidation and degradation under high heat. This makes it suitable for commercial frying and baking applications.
– Long shelf life – Palm oil is able to resist rancidity and spoilage for longer periods compared to most liquid oils. This shelf life stability is a major reason palm oil is added to many processed foods.
How might palm oil extend shelf life?
The primary reason that palm oil is able to extend product shelf life is due to its chemical resistance to oxidation and rancidity.
Oxidation is the reaction of oils with oxygen that leads to degradation over time. The oxidation process causes oils to become rancid, forming undesirable flavors and odors. This makes the products unpleasant and unsafe for consumption.
Palm oil’s chemical structure allows it to better withstand oxidation compared to oils like sunflower, canola, and corn oil. Specifically:
– Saturated fats – The saturated fats in palm oil lack double bonds that are vulnerable to oxidation. Monounsaturated and polyunsaturated fats with double bonds oxidize faster.
– Tocopherols – Palm oil contains tocopherols like vitamin E that act as antioxidants, preventing oxidation reactions.
– Carotenoids – Red palm oil gets its color from carotenoids which also have antioxidant properties.
By resisting oxidation and rancidity, palm oil can increase the shelf life of products like baked goods, snacks, chocolate, and spreads compared to using alternative liquid oils.
Evidence supporting palm oil’s shelf life extending properties
Numerous scientific studies have been conducted that provide evidence that palm oil can prolong shelf life in certain food applications:
– A study published in the Journal of the American Oil Chemists Society showed that palm oil doubled the shelf life of biscuits from 20 days to 40 days compared to biscuits made with sunflower oil.
– Research in the International Journal of Food Properties found that palm oil tripled the shelf life of tomato paste from 5 months to 15 months versus tomato paste with soybean oil.
– Scientists reported in Food Research International that palm oil increased the shelf life of peanut butter to at least 9 months compared to peanut butter with other oils which spoiled in 2-3 months.
– Adding palm oil to wheat bread was shown to double the bread’s shelf life from 3 days to 6 days relative to wheat bread without palm oil, according to a study in LWT – Food Science and Technology.
– Replacing canola oil with palm olein oil in cake batter extended the cake’s shelf life from 5 days to 28 days stored at room temperature based on a study published in the Italian Journal of Food Science.
In most cases, the extended shelf life with palm oil was attributed to greater oxidative stability and lower moisture loss in the palm oil-containing products.
How does palm oil compare to partially hydrogenated oils for shelf life?
Partially hydrogenated oils (PHOs) were previously used in place of palm oil in many processed foods before health concerns over their high trans fat content emerged. Because palm oil is semi-solid and versatile like PHOs, it became an alternative after PHOs were banned starting in 2015.
But how does palm oil compare to PHOs when it comes to extending shelf life?
Several studies have directly compared the shelf life impacts of palm oil versus partially hydrogenated fats:
– One study in the Journal of the American Oil Chemists’ Society found partially hydrogenated soybean oil extended biscuit shelf life to 56 days over palm oil’s 40 days. However, the trans fat content makes PHOs undesirable.
– Research published in Food Chemistry saw PHOs prolong shelf life in vegetable ghee by 50% over palm oil. But again, palm oil is healthier than PHos.
– In most cases, palm oil is able to approach the shelf life enhancing effects of PHOs without the disadvantage of trans fats. The differences are generally small enough to justify palm oil’s use.
So while no oil can match PHOs for resisting oxidation, palm oil comes the closest while remaining trans fat free. The tradeoff of a slightly shorter shelf life is worthwhile to avoid negative health impacts of PHOs.
Does palm oil meaningfully extend shelf life compared to other stable oils?
While palm oil clearly extends shelf life compared to polyunsaturated liquid oils, its advantage over more stable solid fats like cocoa butter or coconut oil is less significant:
– Research in the Journal of Oleo Science showed cocoa butter had similar anti-oxidative properties and shelf life extending impacts to palm oil when tested in potato chips.
– A study in the Journal of Food Processing and Preservation found almost no difference in shelf life between palm oil and coconut oil used in fish crackers stored at room temperature.
– Hydrogenated vegetable oils without trans fats can also match and potentially exceed palm oil’s shelf life impacts as they are similarly semi-solid at room temperature.
This implies the benefit of palm oil over alternative saturated vegetable fats for shelf life may be marginal in many applications. Its advantages for shelf life seem most apparent compared to liquid unsaturated oils.
Does shelf life extension outweigh sustainability concerns over palm oil?
While extending shelf life is advantageous for food manufacturers, the use of palm oil has raised objections regarding its sustainability:
– Forest destruction – Expanding palm oil plantations has caused widespread deforestation, habitat loss, and impacts on endangered species in Southeast Asia and Africa.
– Climate change – Deforestation for palm oil drives greenhouse gas emissions and reduces natural carbon sequestration from forests.
– Labor issues – Forced and child labor concerns have been raised around palm oil production.
– Health concerns – Replacing trans fats with palm oil does not necessarily make products healthier due to its high saturated fat content.
Given these sustainability and health drawbacks, many experts argue that the marginal shelf life benefit of palm oil over alternative oils may not outweigh the environmental and social costs of palm oil production in many cases. However, palm oil cultivation that adheres to certified sustainable practices may help mitigate some of these concerns.
Can you extend shelf life without palm oil?
Food manufacturers have options to extend shelf life that do not involve palm oil:
– **Use antioxidant preservatives** – Ingredients like vitamin E, BHA, BHT, citric acid all slow oxidation.
– **Replace unsaturated fats** – Use more saturated fats like coconut oil and butter that resist oxidation.
– **Add saturated fatty acids** – Stearic acid mimics palm oil’s saturates for shelf life.
– **Improve packaging** – Vacuum sealing, opaque and multilayer packaging blocks oxygen and light.
– **Pasteurize products** – Heat treatment kills microbes that can shorten shelf life.
– **Freeze or dry products** – Removing water inhibits microbial growth and chemical reactions.
– **Acidify foods** – Low pH inhibits microbial growth.
Research is also developing more natural preservatives from herbs, spices, and agricultural waste to replace synthetic additives. Overall, there are options to extend shelf life that food companies may find viable alternatives to palm oil in many applications.
Conclusion
In summary, palm oil is able to extend the shelf life of many baked goods, spreads, snacks, and other processed foods compared to polyunsaturated vegetable oils. This shelf life extension is attributed to palm oil’s chemical resistance to oxidation and rancidity. However, palm oil only provides a marginal improvement over alternative solid oils high in saturated fats. While this shelf life enhancement has driven the widespread use of palm oil, the sustainability impacts of palm oil production have raised concerns that its benefits may not outweigh the environmental and social costs in many cases. Food manufacturers can achieve extended shelf life through various other methods as alternatives to palm oil. But truly evaluating the advantages and disadvantages of palm oil requires carefully weighing its pros and cons.
