Investigations on the formation of Maillard reaction products in sweet cookies made of different cereals

In this study, the content of Maillard reaction products from its initial, intermediate and final stage (5-hydroxymethylfurfural, α-dicarbonyl compounds, furosine, N-ε-carboxymethyllysine and N-ε-carboxyethyllysine) was measured in sweet cookies made of wholegrain flour of eight genotypes of small-grain cereals (bread wheat, durum wheat, soft wheat, hard wheat, triticale, rye, hulless barley and hulless oat) and four corn genotypes (white-, yellow- and red-colored standard seeded corn and blue-colored popping corn). Furthermore, the effect of the initial content of sugars, total proteins, free and total lysine in flour on the formation of Maillard reaction products was investigated using the principle component analysis. 3-deoxyglucosone was the predominant α-dicarbonyl compound in all cereal cookies and the highest content was measured in those made from flour of different colored corn genotypes (on average, 98.35, 151.28 and 172.85 mg/kg after baking for 7, 10 and 13 min, respectively). Heating dough at 180 °C for 7, 10 and 13 min differently affected the content of 5-hydroxymethylfurfural and α-dicarbonyl compounds in the cereal cookies. The 5-hydroxymethylfurfural content gradually increased, while a reduction in 3-deoxyglucosone content was observed in the cookies baked for 13 min except for those made from soft wheat, hulless oat, red- and blue-colored corn. After 7 min of heating, the content of furosine measured in the cereal cookies reached its maximum (from 320.9 mg/kg in yellow-colored corn-based cookies to 585.7 mg/kg in hulless oat-based cookies), while N-ε-carboxymethyllysine and N-ε-carboxyethyllysine showed the opposite trend. The highest content of advanced glycation end products was detected in cookies also made from hulless oat flour rich in proteins (16.80%) and total lysine (10670.3 mg/kg). The interrelationship analysis showed that the initial content of sugars in flour of cereals affected 5-hydroxymethylfurfural and 3-deoxyglucosone formation in the cookies. In addition, a high correlation between protein-bound Maillard reaction products in the cookies and the total proteins and the total lysine content in the flours was found.