Impact of seed-roasting treatment on polycyclic aromatic hydrocarbons, 3-MCPD esters, heterocyclic amines and volatile components formation in sunflower oil

Abstract

Seed-roasting is a crucial process conducted to improve the organoleptic and conservative features of oilseeds. In this paper, raw sunflower seeds were roasted at 160, 180 and 200 °C for various times. Three hazards (polycyclic aromatic hydrocarbons, 3-monochloro-1,2-propanediol esters and heterocyclic amines) and volatile components in the corresponding oil extracted from roasted sunflower seeds were analyzed. Polycyclic aromatic hydrocarbons, 3-monochloro-1,2-propanediol esters and heterocyclic amines were measured using HPLC, GC-MS and UPLC-MS, respectively. Volatiles were determined by GC-MS. The results show that the strength of seed-roasting promoted the formation of the three hazard factors. The contents of polycyclic aromatic hydrocarbons, 3-monochloro-1,2-propanediol esters and heterocyclic amines in sunflower oil increased 9.4, 22.1 and 121.6 fold respectively after roasting at 200 °C for 25 min. The main volatiles were aldehydes and terpenes with a greenish and earthy taste. Volatile levels possessing pleasant flavors of floral, roasted and nuts, particularly aldehydes and pyrazines, generally increased with roasting. However, at high intensity roasting, the appearance of furans would bring burnt, bitter, as well as viscosity, resulting in poor sensory for oil. Considering the limitation of the above mentioned hazards established by EU, the optimal roasting condition of sunflower seed was 180–200 °C for 15–20 min.