Roasting of hazelnuts. Role of oil in colour development and hydroxymethylfurfural formation

The roles of oil, hexanal and sucrose were investigated in colour development and HMF formation during roasting of hazelnuts. The highest HMF levels and the deepest browning extension were in crushed hazelnuts and the lowest HMF and browning were in defatted or partially defatted samples. The addition of hexanal, at 175 °C, increased the HMF level. This was particularly evident in samples with sucrose. Moreover samples totally reintegrated in oil did not reach (after roasting) the same HMF level and colour as the corresponding crushed samples.