The Secret of Perfect Frying

The Role of Sugars in Potatoes in Acrylamide Formation During the Frying Process

Industrial frying of potatoes is a process used worldwide to create a crispy and delicious snack. This process can pose a risk to human health in the form of acrylamide, a carcinogenic chemical formed during cooking at high temperatures. To ensure the food safety and quality of crisps, it is essential to carefully evaluate both the oil used and the potatoes themselves.

The Formation of Acrylamide
Acrylamide is a chemical that forms naturally during high-temperature cooking of foods containing starch, sugars and amino acids, such as potatoes. This chemical process occurs during the Maillard reaction, which gives the characteristic golden colour and flavour to crisps. It is formed mostly from sugars (glucose and fructose) and amino acids (mainly an amino acid called asparagine) naturally present in many foods. The presence of acrylamide has been found in products such as crisps, french fries, bread, biscuits and coffee.

The Quality of Oil
A key step in producing high-quality crisps is the use of good quality frying oil. The oil should be chosen carefully, taking into account its thermal stability and smoke point. An oil with a high smoke point will withstand high temperatures better without degrading.

In addition, it is critical to regularly monitor the quality of the oil during the frying process. Oil temperature, soaking time and the amount of oil used affect the final result. Analysis of acidity, peroxides and p-anisidine allows you to keep an eye on the state of oxidation and decide how to manage the system. Used oils should be filtered and changed periodically to prevent them from degrading and producing unwanted substances.

The Quality of Potatoes
The various existing potato cultivars contain the main precursors of acrylamide (amino acids and reducing sugars) and are therefore predisposed to its formation during cooking. The vulnerability of potatoes to acrylamide formation is explained by the abundant presence of free asparagine, an amino acid that is proportionally much more abundant in the tuber than the reducing sugars.

This means that although both compounds are involved in the formation of acrylamide, the amount of reducing sugars acts as a decisive factor in acrylamide production because the glucose and fructose values present in the tuber can vary greatly between different cultivars. A direct and significant link between the level of acrylamide generated and the amount of these sugars has been observed through various research studies. Ideally, potatoes intended for frying should have a concentration of reducing sugars of less than 0.5 percent by dry weight.

Analysis of glucose and fructose is therefore a key check to be made on the incoming raw material and also during storage, as these sugars also tend to increase rapidly depending on storage conditions. In addition to acrylamide formation, a high sugar content in potatoes can also lead to excessive coloration during frying and an altered taste. With the CDR FoodLab analysis system, it is now possible to determine the level of sugars (glucose and fructose) in potatoes after briefly processing the sample.

CDR FoodLab
The FoodLab is widely used by manufacturers of crisps and snacks to monitor the quality of frying oil through the determination of free fatty acids, peroxide value and p-anisidine value.

  • Analysis is very quick and relies on analysis methods that are compliant with reference methods
  • Analysis can be performed at any time in the production plant, in large quantities
  • The FoodLab saves time and cuts analysis costs
  • The simplicity and rapidity of the analysis method allows anyone to perform the tests
  • The analyser uses pre-filled cuvettes and reagents that do not require a chemical laboratory

Dr. Simone Pucci, Head of CDR Chemical Lab
Expert in chemical analysis of olive oil, food, and beverages.

References

  • De Wilde T. et al. “Selection Criteria for Potato Tubers To Minimize Acrylamide Formation during Frying.” Journal of Agricultural and Food Chemistry – April 2006
  • J. Stephen Elmore et al. “Acrylamide in potato crisps prepared from 20 UK-grown varieties: Effects of variety and tuber storage time.” Food Chemistry – February 2015

25/6/24

Long Man Brewery Mashing Efficiency
Long Man Brewery Mashing Efficiency

Acrylamide concentration as a function of the reducing sugar content in the potato tubers