2.1. Fat extraction—Determination of peroxide value
The fat from chocolate bars was extracted using the Welmann
method (G.S.C.L., 1976): Crushed dark chocolate with hazelnuts (5 g)
was transferred into a separatory funnel with 100 mL of diethyl ether
and 10mL of distilled water. The separatory funnel was agitated for
2 minutes and subsequently left to equilibrate for 24 h. Fifty milliliter
of the sample was transferred to a crystallizing dish and diethyl ether
was evaporated in a water bath at 40 °C. The extracted fat was dried in
an oven at 105 °C for 3 min, and the residue was used to determine
the peroxide value. The peroxide value was determined according to
the official Commission Regulation (EC) (1991) method.