Abstract: The formation mechanism of endogenous formaldehyde in toffee was studied by glycerol system. High performance liquid chromatography (HPLC)-derived liquid extraction method was used to determine formaldehyde. The results showed that glycerol could collect formaldehyde efficiently during the production of toffee. As major compositions of toffee, milk powder plays an important role in the generation of formaldehyde. The major reason for the generation of endogenous formaldehyde in toffee was Maillard reaction between casein and lactose. The content of formaldehyde and its variation tendency in casein-lactose-glycerol system treated at 60—120 ℃ for 1 h was similar with milk powder-lactoseglycerol system under the same condition. Positive correlation between formaldehyde content and high temperature treatment was observed. Different kinds of carbohydrates play different roles in the generation of formaldehyde. The most obvious impact was glucose, which was followed by fructose, lactose and sucrose.

Key words: formaldehyde, toffee, milk powder, casein, carbohydrate, Maillard reaction