Kinetic Model for the Formation of Acrylamide during the Finish-Frying of Commercial French Fries

Abstract

Acrylamide is formed from reducing sugars and asparagine during the preparation of French fries. The commercial preparation of French fries is a multistage process involving the preparation of frozen, par-fried potato strips for distribution to catering outlets, where they are finish-fried. The initial blanching, treatment in glucose solution, and par-frying steps are crucial because they determine the levels of precursors present at the beginning of the finish-frying process. To minimize the quantities of acrylamide in cooked fries, it is important to understand the impact of each stage on the formation of acrylamide. Acrylamide, amino acids, sugars, moisture, fat, and color were monitored at time intervals during the frying of potato strips that had been dipped in various concentrations of glucose and fructose during a typical pretreatment. A mathematical model based on the fundamental chemical reaction pathways of the finish-frying was developed, incorporating moisture and temperature gradients in the fries. This showed the contribution of both glucose and fructose to the generation of acrylamide and accurately predicted the acrylamide content of the final fries.

Thermal generation or aroma

“…However, the breakdown of the asparaginecontaining Schiff base is different and acrylamide is formed. The specific amino acid pathway was proposed by Zyzak et al (2003) and shows acrylamide being formed directly from the glucose-asparagine Schiff base and bypassing both the formation of the ARP and the fragmentation of the sugar (Parker et al, 2012). It is likely that these two routes exist in parallel and their relative contributions are influenced by the other components of the system.…”

“…This poses a challenge for the food industry because many strategies to reduce acrylamide, also reduce flavour formation. Such are the complexities of the Maillard reaction that several authors have turned to mathematical kinetic modelling based on the underlying chemistry to determine the control points in the reaction (Low et al, 2007;Parker et al, 2012) and develop strategies to minimise acrylamide whilst maintaining flavour.…”

“…Strecker aldehydes, aldol condensates, pyrazines and sulfides all increased, and there was a sixfold increase in acrylamide, confirming the relationship between acrylamide and flavour and a common formation pathway. Manipulation of glucose and fructose levels in potato strips prior to frying was shown to alter the formation of acrylamide, with exchange of fructose for glucose giving less acrylamide for a given colour in the final French fry (Parker et al, 2012). In one study dedicated to reduction of acrylamide in potato cakes, high levels of glycine were added to potato dough prior to cooking.…”

Acrylamide levels in potato crisps in Europe from 2002 to 2016

“…Free asparagine concentration has more influence in French fry rather than crisping varieties, probably because French fry varieties contain higher concentrations of sugars (Halford et al 2012b;Muttucumaru et al 2014), and modelling of the relationship between the ratio of free asparagine to reducing sugars in potatoes with unusually low concentrations of free asparagine from a U.K. field trial identified a ratio of free asparagine to reducing sugars of 2.257 ± 0.149 as a tipping point below which free asparagine concentration could affect acrylamide formation (Muttucumaru et al 2017). Another study modelled the kinetics of acrylamide formation in French fry production and concluded that both the fructose/ glucose ratio and the ratio of asparagine to total free amino acids could affect acrylamide formation (Parker et al 2012).…”

Maillard Reaction Products: Occurence, mitigation strategies and their physiological relevance

“…dry biscuits values range from 0.5 to 182.5 mg/kg [42][43][44] ; breakfast cereal values range from 3.7 to 193 mg/kg 43 ; toasted bread values range from 11.8 to 90 mg/kg 43,45 .…”