Acrylamide in Baking Products: A Review Article

More documents

Recommendations

Info

Food Bioprocess Technol (2011) 4:530–543 533have focused on reducing or diluting precursors such asfree asparagine: (1) consuming asparagine by either addingan enzyme or using yeast or another microorganism(Fredriksson et al. 2004; Hamlet et al. 2005); (2) addingother amino acids (Brathen et al. 2005; Claeys et al. 2005);(3) binding asparagine with a complexing agent, forexample by adding divalent metal ions (Gökmen andSenyuva 2007; Lindsay and Jang 2005); and (4) removingaccelerants such as ammonium salts (Amrein et al. 2004,2006; Biedermann and Grob 2003).It is assumed that the mechanism leading to theformation of acrylamide derives from Maillard reaction,i.e. the reaction between reducing sugars and proteins/aminoacids (mainly asparagine; Fig. 2). However, other routes mayalso be responsible (Wenzl et al. 2003; Stadler et al. 2002;Becalski et al. 2003; Mottram et al. 2002). There are similarconfusions about the effects of the amount of precursors onacrylamide formation. For instance, addition of 35 mmol/kgof glucose and fructose in a model system includingreducing sugar and asparagine increased acrylamideformation, but the extreme addition of glucose (up to140 mmol/kg) would decrease the acrylamide content tolower than that expected from 35 mmol/kg addition. Also,the addition of protein or amino acids could to someextent lead to a reduced formation of acrylamide.pH and MoistureThe effects of pH and moisture content have also beeninvestigated. Researchers showed that the addition ofconsumable acids is a very simple but efficient method ofminimizing acrylamide in bakery products. When increasingamounts of citric acid were added to baked corn chips,acrylamide decreased almost linearly (Jung et al. 2003).Similar effects were reported when lactic, tartaric, citric andhydrochloric acids were added to semi-finished biscuits andcracker models (Graf et al. 2006; Levine and Smith 2005;Taeymans et al. 2004). Addition of acidity has been shownto result in a decreased acrylamide formation, but to anincreased degradation of the acrylamide formed. Generationis significantly reduced due to hydrolysis of the carboxamidegroup leading to aspartic acid at lower pH.Furthermore, reduced pH values resulted in only moderateMaillard reactions, accompanied by lower acrylamideformation. There are some complexities about the effectof water activity. For example, acrylamide is not formedbefore water activity is reduced to below 0.8, and in lowwater activity foods, maximum acrylamide formation isobserved when water activity is about 0.4; further reductionof water activity tends to decrease the amount of acrylamide(Eriksson 2005; Stadler et al. 2002; Mottram et al.2002; Biedermann et al. 2002a, b; Weisshaar 2004;Hoenicke and Gatermann 2004, 2005; Delatour et al.2004; Brathen and Knutsen 2005).Lipid OxidationLipid oxidation is one of the major chemical reactionsoccurring during food processing or storage and may have astrong impact on the final quality of foods. It is well knownFig. 2 Proposed mechanism forthe formation of acrylamide inheat-treated foods (HEATOXProject 2007)
534 Food Bioprocess Technol (2011) 4:530–543that lipids (triglycerides) produce a large amount of acroleinby heat treatment (Umano and Shibamoto 1987). Acroleincan further react via oxidation to generate acrylic acid or byformation of an intermediate acrylic radical. Both of theintermediates could then induce acrylamide formation inthe presence of a nitrogen source under favourable reactioncircumstance in lipid-rich foods upon heat treatment(Fig. 3). In a model system using asparagine, significantamounts of acrylamide (114 μg/g of asparagine) wereformed, but under the same condition using glutamine,acrylamide was formed only at the level of 0.18 μg/g ofglutamine. Considering that both amino acids contain anamide moiety, this may be due to differences in the amountof ammonia formation from asparagine and glutaminerather than due to their amide moiety. Also, asparaginemay produce a three-carbon unit more readily thanglutamine does (Yasuhara et al. 2003).Researches showed that some secondary lipid oxidationproducts can convert amino acids into the correspondingvinylogous derivatives (Hidalgo and Zamora 2007; Zamoraet al. 2007), and some lipid oxidation products can degradeasparagine to acrylamide (Zamora et al. 2007). Theyproposed α,β,γ,δ-diunsaturated carbonyl compounds asthe most reactive, followed by hydroperoxides, likelybecause of their thermal decomposition upon heating.Arribas-Lorenzo et al. (2009) investigated the effect of oiloxidation level as well as the oil phenol profile onacrylamide formation in cookies and claimed that lipidoxidation products can be regarded as an important factor inacrylamide formation in fat-rich dry foods and that theamount and the type of antioxidant compounds of oilclearly affect acrylamide concentrations after baking.Capuano et al. (2010) showed that oil oxidation levelpositively influences the formation of acrylamide indifferent formulations with three oil samples at differentoxidation levels, but catechin presence reduced acrylamideformation in systems containing unheated oil and partiallyoxidized oil whilst no significant lowering effect wasobserved when highly oxidized oil was used.In sugar-containing model systems, lipid oxidation levelmoderately influenced acrylamide formation, whilst theeffect became more pronounced in systems with low watercontent and with low carbohydrate concentration. The typeof oil or fat used in the formulation also influencesacrylamide levels (Fig. 4), with acrylamide formationhigher in systems containing sunflower oil than in systemsmade with palm oil, which has a lower susceptibility(Capuano et al. 2010).Fig. 3 Hypothesized formation mechanisms of acrylamide from an amino acid and a lipid (Yasuhara et al. 2003)
Page 1: Food Bioprocess Technol (2011) 4:53
Page 6 and 7: Food Bioprocess Technol (2011) 4:53
Page 14: Food Bioprocess Technol (2011) 4:53

Acrylamide in Baking Products: A Review Article

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?