A novel infrared roasting to improve the flavour profile of virgin rapeseed oils

In this work, a novel roasting method for virgin rapeseed oil (VRO) production was proposed. The effect of infrared roasting (IR) on oxidation stability, Maillard reaction, glucosinolate degradation and volatiles of VRO was evaluated at 110-170 & DEG;C. The results showed that VROs from IR exhibited better oxidation stability (higher oxidative stability index and DPPH radical scavenging activity) of VROs than that from traditional roller roasting (TRR). This was attributed to the higher contents of tocopherols (748.78 mg kg-1) and canolol (680.69 mg kg-1) measured in IR-VROs than tocopherols (682.15 mg kg-1) and canolol (564.28 mg kg-1) in TRR-VROs. IR could provide a more effective thermal fracture of rapeseed, facilitating to higher releases of tocopherols and canolol. Moreover, during IR, free amino acid (from 25.60 to 15.03 mg kg-1), reducing sugars (from 7.65 to 2.04 mg kg-1) and glucosinolate (from 28.73 to 13.00 mg kg-1) were decreased more than TRR, especially at 150 & DEG;C, indicating more intense Maillard reaction and glucosinolate degradation. Hence, more nitriles/isothiocyanates (657.43 & mu;g kg-1) and pyrazines (269.64 & mu;g kg-1) were generated in IR-VROs than TRR-VROs (600.82 and 163.89 & mu;g kg-1, respectively). From sensory analysis, the flavour profile of IR-VRO was more than TRR-VRO at 150 & DEG;C. IR holds the potential to produce VROs with better flavours. IR-rapeseed exhibited more effective thermal fracture compared with TRR, facilitating canolol release to improve oxidation stability. Moreover, Maillard reaction and glucosinolates degradation were promoted largely during IR due to the effective thermal fracture. Therefore, IR-VRO has better flavour profile than TRR-VRO.image