Influence of roasting temperature of pumpkin seed on PAH and aroma formation

Abstract

Pumpkin (Cucurbita pepo L.) seed oil is an edible oil, a traditional product of eastern Slovenia, and is used for cold dishes, such as salads. After roasting at about 110°C, the pumpkin seeds are squeezed into dark green oil with typical flavor and aroma. During roasting, polycyclic aromatic hydrocarbons (PAHs) can form. In this study, the aroma composition and PAH formation in oil samples from seeds roasted at different temperatures were determined. Seeds were roasted at temperatures ranging from 90 to 200°C. High‐performance liquid chromatography with fluorescence detection for PAH determination and gas chromatography coupled with mass spectrometry for volatile compound determination were used. At 150°C, the formation of PAHs was detected. Light PAHs prevailed, especially phenanthrene. Increasing roasting temperature also significantly changed the composition of volatile compounds composition. Aldehydes and alcohols prevailed at low roasting temperatures. High temperature caused the formation of different pyrazines, which possess a roasted aroma.Practical applications: Results of this study provide information about the influence of roasting pumpkin seeds on their quality and safety. Data indicate which temperature to use to obtain a safe product, pumpkin seed oil that does not contain PAHs. Increasing roasting temperature is responsible for changes in the volatile compound composition. The aroma varies from green and fresh to roasted and burnt. The customer expects pumpkin seed oil to possess the typical aroma; thus the choice of temperature is essential. Results of this study can be applied at all pumpkin seed oil production sites and are transferable to other edible oils for which elevated temperatures are used during production.Thermal treatment – roasting of pumpkin seeds can cause polycyclic aromatic hydrocarbon formation and significantly influences on aroma composition of pumpkin seed oil.