Free Amino Acids and Sugars in Rye Grain: Implications for Acrylamide Formation

Abstract

Acrylamide forms from free asparagine and sugars during cooking, and products derived from the grain of cereals, including rye, contribute a large proportion of total dietary intake. In this study, free amino acid and sugar concentrations were measured in the grain of a range of rye varieties grown at locations in Hungary, France, Poland, and the United Kingdom and harvested in 2005, 2006, and 2007. Genetic and environmental (location and harvest year) effects on the levels of acrylamide precursors were assessed. The data showed free asparagine concentration to be the main determinant of acrylamide formation in heated rye flour, as it is in wheat. However, in contrast to wheat, sugar, particularly sucrose, concentration also correlated both with asparagine concentration and with acrylamide formed. Free asparagine concentration was shown to be under genetic (G), environmental (E), and integrated (G x E) control. The same was true for glucose, whereas maltose and fructose were affected mainly by environmental factors and sucrose was largely under genetic control. The ratio of variation due to varieties (genotype) to the total variation (a measure of heritability) for free asparagine concentration in the grain was 23%. Free asparagine concentration was closely associated with bran yield, whereas sugar concentration was associated with low Hagberg falling number. Rye grain was found to contain much higher concentrations of free proline than wheat grain, and less acrylamide formed per unit of asparagine in rye than in wheat flour.

Acrylamide in Baking Products: A Review Article

“…These results clearly show that low acrylamide yeast-leavened breads should be baked with ingredients with a low level of free asparagine or a process that lowers the content of free asparagine before it is converted to acrylamide (Surdyk et al 2004). Curtis et al (2010) studied acrylamide precursors (free amino acid and sugar concentrations) in rye varieties and showed free asparagine concentration to be the main determinant of acrylamide formation in heated rye flour, as it is in wheat. Hamlet et al (2008) showed that in cooked flours and doughs (mainly rye and wheat), asparagine was the key determinant of acrylamide generation.…”

Evidence for the complex relationship between free amino acid and sugar concentrations and acrylamide‐forming potential in potato

“…Acrylamide formation was measured in flour after heating at 160°C for 20 min. This method has already been used in several studies because it gives high levels of acrylamide formation, providing a good, consistent indication of acrylamide-forming potential in different raw materials (Curtis et al , 2009, 2010; Elmore et al , 2007; Halford et al , b 2012; Muttucumaru et al , 2006; Postles et al , 2013). Note that free amino acid and acrylamide data were not obtained for unstored Daisy, Umatilla Russet and Harmony because of spoilage of the samples.…”

“…Regression analysis is a purely statistical exercise, but the contrasting models do reflect the fact that free asparagine concentration is the major determinant of acrylamide-forming potential in cereal flour (Curtis et al , 2009, 2010; Granvogl et al , 2007; Muttucumaru et al , 2006; Postles et al , 2013), while sugars are more important in potato, and the fact that other amino acids than asparagine contribute to the variance in both models suggests that this is worthy of further investigation.…”

Mitigation of Acrylamide in Foods: An African Perspective

“…Although different authors, government agencies and international organizations have backed and supported genetic modification, there is still a stiff opposition against its acceptance. Inconsistencies in free sugar, amino acid and asparagine contents in crops of different cultivars (varieties) and genotypes however suggest that the varying concentration of these parameters is due to genetic variations [19,29,38,114]. Consequently, fast tracking the natural breeding process through the use of genetic engineering to develop cultivars (varieties) with lower concentration of asparagine and reducing sugars should be possible and encouraged [35].…”