Choosing the right potato cultivar is an important step to reduce acrylamide formation. Some cultivars are more suitable than others to make chips thanks to their size, shape and low-reducing sugar content. The composition of raw potatoes is a primary factor in acrylamide formation, followed by the frying temperature.
Acrylamide formation during frying has been attributed to Maillard reactions, which develop from reducing sugars and asparagine depending on frying temperature.
A low reduction of sugar content has been recommended to make chips; however, the way the complexity of the medium affects chemical reactions, promoting acrylamide formation during frying, is yet unclear.
Technicians from the Universitat Politècnica de Catalunya BarcelonaTech (Spain) compared three cultivars (Kennebec, Red Pontiac and Agria) to determine the relation between acrylamide precursors in raw potatoes and the properties of chips.
Experiments were carried out in three conditions (190°C for 160 sec; 170°C for 240 sec; 150°C for 330 sec) to obtain similar chips.
Acrylamide levels in different chips depending on cultivar and frying temperature. Lower case letters (a, b, c) indicate cultivar differences at the same temperature, while upper case letters (A, B, C) indicate the difference in temperature with the same cultivar.
Acrylamide levels in different chips depending on cultivar and frying temperature. Lower case letters (a, b, c) indicate cultivar differences at the same temperature, while upper case letters (A, B, C) indicate the difference in temperature with the same cultivar.
"Acrylamide increases with higher frying temperatures, but cultivars behave differently. As regards Red Pontiac, a significant increase of acrylamide was detected at 170°C (~ 40%) as well as an increase in colour. In addition, lower oil absorption and higher humidity content were obtained with a higher temperature. Significant positive correlations were observed between the acrylamide content and reducing sugars and sucrose in raw potatoes."
The acrylamide content in Agria potatoes could be due to sucrose hydrolysis during frying. A significant positive correlation was noticed in chips between shear force and acrylamide. All significant correlations obtained between colour and structure, colour and oil absorption, structure and acrylamide content, indicate that there is an intrinsic relation between chip characteristics and acrylamide content.
Frying at 190°C produced chips with a higher acrylamide content, lower oil absorption, higher humidity as well as a darker colour and toughness than those fried at 150°C.
Reducing sugars and asparagine aside, there are also other aspects of acrylamide formation. "Sucrose and oil absorption may have played an important role in the final acrylamide concentration, so these aspects must be kept into consideration. According to our findings, chips fried at 170-190°C - which had a humidity content over 65% and an absorbed oil content over 15% - may have a higher acrylamide content."
After these first results, the research will continue to assess the various correlations, especially for potatoes with a low-sugar content.
Source: Yali Yang, Isabel Achaerandio, Montserrat Pujolà, 'Influence of the frying process and potato cultivar on acrylamide formation in French fries', 2016, Food Control, Vol. 62, pag. 216–223.
www.sciencedirect.com/science/article/pii/S0956713515302504