Understanding the Link Between Cold Storage and Acrylamide
Acrylamide is a chemical compound that forms naturally during high-temperature cooking methods, such as frying, baking, and roasting, in certain starchy foods like potatoes. The chemical reaction, known as the Maillard reaction, requires two key components: an amino acid called asparagine and reducing sugars (like glucose and fructose). When raw, starchy foods containing these compounds are exposed to temperatures above 120°C (248°F), the reaction occurs, leading to browning, flavor development, and the creation of acrylamide.
The Science of Cold-Induced Sweetening
When raw potatoes are stored in cold temperatures, specifically below 6°C (43°F), they undergo a process known as "cold-induced sweetening". This is a natural defense mechanism where the potato's enzymes convert stored starch into sugars. This process is the primary reason why storing potatoes in the fridge causes acrylamide potential to increase. The resulting higher concentration of reducing sugars means there is more fuel available for the Maillard reaction to produce acrylamide during high-heat cooking.
How Cooking Methods Impact Acrylamide Formation
Not all cooking methods are equal when it comes to acrylamide. The amount produced varies significantly depending on the method used. Frying and roasting are major contributors, while boiling and steaming do not produce acrylamide because the temperature does not get high enough.
Common cooking methods and their effect on acrylamide:
- Frying: Produces the highest levels of acrylamide, especially when cooked to a dark brown color.
- Roasting: Generates less acrylamide than frying, but still a notable amount, especially in browner areas.
- Baking: Also produces acrylamide, though levels can be lower if the potato isn't over-cooked or browned excessively.
- Boiling and Steaming: These methods cook potatoes at temperatures below the threshold required for the Maillard reaction, so no acrylamide is formed.
Proper Potato Storage to Minimize Acrylamide
The best way to minimize the formation of acrylamide in your food is to follow proper storage guidelines. This prevents the initial buildup of excess sugars in the potatoes. Here's a quick checklist for optimal storage:
- Store raw, unpeeled potatoes in a cool, dark, and dry place.
- The ideal temperature is above 6°C (43°F) but below room temperature—think a pantry, cupboard, or basement.
- Keep potatoes away from light to prevent greening and the development of a toxin called solanine.
- Do not wash potatoes before storing, as moisture encourages spoilage.
- Ensure good air circulation by keeping them in a paper bag, wire basket, or an open container.
Comparison of Potato Storage Methods
This table summarizes the different impacts of common storage methods on acrylamide formation when the potatoes are later cooked at high temperatures.
| Storage Method | Effect on Sugar Content | Acrylamide Potential When Cooked | Other Impacts |
|---|---|---|---|
| Refrigerator (Below 6°C) | Starch converts to reducing sugars (cold-induced sweetening). | High. Increased sugars lead to more acrylamide during high-heat cooking like frying or roasting. | Can cause discoloration and an unpleasantly sweet or gritty flavor. |
| Cool, Dark Place (6°C to 15°C) | Slows down or prevents sugar conversion. | Low. Stable sugar levels mean less acrylamide is formed during cooking. | Prevents sprouting, greening, and spoilage for several weeks. |
| Room Temperature (20°C+) | Can accelerate sprouting and spoilage. | Moderate. While sugar conversion is not an issue, faster spoilage is. | Shorter shelf life; can lead to soft, shriveled, or sprouted potatoes. |
A note on conflicting advice
While the conventional wisdom and much of the scientific literature have pointed to an increased acrylamide risk from refrigeration, a 2020 study reviewed by the UK's Food Standards Agency (FSA) found that home storage of potatoes in a fridge might not significantly increase the acrylamide-forming potential compared to a cool, dark place. However, this is largely viewed as an outlier finding among a larger body of evidence showing a clear link between cold-induced sweetening and higher acrylamide levels. The FDA and Health Canada continue to advise against storing raw potatoes in the fridge for this reason. Given the conflicting information, the safest and most widely accepted practice remains storing raw potatoes in a cool, dark place, above 6°C.
The Final Verdict on Storing Potatoes in the Fridge
Ultimately, there is a clear and well-documented chemical reason for avoiding the refrigeration of raw potatoes, especially if they will be cooked using high-heat methods. Cold-induced sweetening increases the amount of sugar available for the Maillard reaction, which in turn leads to higher levels of acrylamide formation. While the health risks from dietary acrylamide are still being evaluated by international health organizations, most agree that it is prudent to minimize exposure where possible. Proper storage in a cool, dark pantry or basement, combined with optimal cooking practices like soaking and aiming for a light golden color, provides the best defense against acrylamide formation. By following these simple steps, you can enjoy delicious, perfectly cooked potatoes with confidence.
Conclusion
Does storing potatoes in the fridge cause acrylamide? Yes, indirectly. Storing raw potatoes in the refrigerator promotes the conversion of starches into reducing sugars. When these sugar-enriched potatoes are then cooked at high temperatures, the Maillard reaction is accelerated, leading to significantly higher levels of acrylamide. To mitigate this risk, storing potatoes in a cool, dark place (not the fridge) is the recommended best practice. This simple storage adjustment, along with modifying cooking techniques, is an effective way for home cooks to reduce their dietary exposure to this chemical.
Other ways to reduce acrylamide
- Soak before cooking: Soaking cut potato pieces in water for 15–30 minutes before frying or roasting can help remove excess surface sugars and reduce acrylamide formation.
- Don't over-brown: When frying, baking, or roasting, cook starchy foods to a light golden yellow color rather than dark brown. Darker areas indicate higher levels of acrylamide.
- Choose alternative cooking methods: For less acrylamide exposure, opt for boiling, steaming, or microwaving potatoes.
- Follow package instructions: For pre-packaged potato products like fries, follow the manufacturer's cooking instructions, which are often optimized for lower acrylamide levels.
