Maillard reaction derived from oil-tea camellia seed through roasting

The Maillard reaction products (MRPs) formed after roasting of oil-tea camellia seeds (camellia seeds) were investigated. Camellia seeds are inevitably heated during processing, but the effect of heating or roasting on the physicochemical properties of camellia seed or oil-tea camellia seed oil (camellia oil) has been seldom studied, especially with respect to the Maillard reaction.

Changes in reducing sugars, free amino acids, pH, color, browning intensity and MRP (furosine, glyoxal, methylglyoxal, 5-hydroxymethylfurfural and furural) concentrations were examined in camellia seeds during roasting at 120-160 °C for 20-120 min. Results showed that roasting leads first to a decrease and then to a considerable increase in free amino groups and, at the same time, to a reduction in moisture content and decrease in pH. The sucrose content of the seeds decreased, while that of glucose and fructose increased reciprocally during roasting. On the other hand, the observed changes concerning glyoxal were negligible. Furthermore, 5-hydroxymethylfurfural and furfural have been found at the end of the roasting process, with maximum values of 572.26 ± 1.91 mg kg^-1 dry wt and 0.46 ± 0.003 mg kg^-1 dry wt, at 160 °C for 120 min, respectively.

This investigation provides the initial groundwork necessary for the development and implementation of green and efficient technology that could be applied to obtain high-quality camellia oil. Future research is necessary to assess antioxidant capacity, quality and safety of oil after thermal processing of camellia seeds. © 2019 Society of Chemical Industry.