Acrylamide: A Review of Its Formation and Health Effects Josh Lobsenz Abstract: With the rise of genetically modified organisms and public support of food being “locally sourced”, “organic”, or “farm-to-table”, chemicals within food, such as acrylamide, have come under scrutiny. This paper will examine how acrylamide is formed in food and its potential health effects on humans. Acrylamide is a chemical that is found in foods when cooked with certain hightemperature methods,1 such as frying and grilling. It consists of an amide whose nitrogen is bonded to two hydrogens and whose carbon is bonded to an ethene (see Figure 1 below).
Figure 1: The structure of acrylamide.2 Acrylamide is formed via the Maillard reaction. In general, a Maillard reaction consists of a reducing sugar reacting with an amino acid at a high temperature; since almost all food contains at least some sugars and protein, Maillard reactions occur when food is cooked. It can manifest itself as the browning and flavor of meat, the color of toast, and the taste and golden-brown color of fried food.3 So how does the reaction work? (In order to simplify, this paper will only discuss the Maillard reaction with regard to creating acrylamide, as Maillard reactions can produce a multitude of other compounds.)
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The process begins with one of a handful of amino acids: asparagine, methionine, glutamine, cystine, and aspartic acid. Of these, asparagine is most commonly referenced and results in the highest levels of acrylamide, so it will be the amino acid used in this paper’s mechanism. Asparagine reacts with a sugar’s carbonyl group, and, via dehydration, a double bond is created between the non-amidic nitrogen and the formerly carbonyl carbon, resulting in a Schiff base (see Figure 2).
Figure 2: A Schiff base.4 The Schiff base releases a carbon dioxide molecule, and the nitrogen accepts a hydrogen atom, making it positively charged; this causes the double bond and negative charge to alternative between the two carbons, creating resonance. Both forms of the molecule become acrylamide, though by different means. In one, a hydrogen shifts onto the anionic carbon, stabilizing it, breaking it off from the nitrogen, and creating acrylamide. For the other form of the resonant molecule, water enters the system and breaks it up into an aldehyde and 3aminoproprionamide; in the latter of these, the nitrogen takes a hydrogen atom from the carbon and breaks free, forming ammonia. The unstable carbon then accepts a hydride shift and forms a double bond with the adjacent carbon, creating acrylamide.5,6,7 The mechanism is shown in Figure 3. Temperature is also an important factor in the accumulation of acrylamide (see Figure 4). Acrylamide will not form below
