Lysine availability is diminished in commercial fibre-enriched breakfast cereals

Furosine is a heat-induced marker for thermal treatment in foodstuffs and is directly related to the loss of lysine availability. Furosine was analysed in 60 commercial breakfast cereals in order to assess the protein nutritional value. Samples were hydrolysed with 7.95 M HCl at 110 °C for 23 h, clarified by solid-phase extraction and furosine quantified by ion-pairing HPLC. Statistical analyses were applied according to the type of cereal (corn, wheat, rice or mixture), the addition of cocoa powder, sugar content, dietary fibre and protein content, physical form of the product, as well as the consumers for whom they are intended (adults or infants). Data showed a statistically significant effects of protein content, added-dietary fibre and physical form of the samples (flakes/puffed) on the level of furosine present in commercial breakfast cereals. The higher the protein content in the formulation, the higher were the furosine levels, regardless of the protein source. Significantly higher furosine levels were found in puffed commercial breakfast cereals. Fibre-enriched commercial breakfast cereals showed the most marked reduction of nutritional properties.