Frying is a culinary technique that allows in quick way to obtain dishes with the organoleptic qualities desired by consumers. It consists in thermal processing of food products using hot oil as a frying medium. However, the high temperature used during this process causes oil degradation and the formation of numerous harmful to health products. Oils obtained by supercritical fluid extraction (SFE) with CO2 are characterized by a unique composition of the unsaponifiable fraction. Due to this, their blends with refined rapeseed oil can exhibit increased thermal stability. The aim of the research was to determine the effect of the lupine oil SFE addition on the degradation of triacylglycerols (TAG) in blends with refined rapeseed oil at high temperature. Refined rapeseed oil without additives, refined rapeseed oil with the addition of TBHQ and refined rapeseed oil with the addition of 5 and 25% SFE lupine oil were tested.
FRY-003: Limitation of Triacylglycerols Thermal Degradation by the addition of Lupine Oil SFE
Afterwards the oils and blends were heated in a thin layer at 170 and 200°C. In all unheated and heated samples, the total polar content (TPC), TAG oxidized monomers content and TAG polymers content were determined. The TPC increase in the samples oil heated at 170°C with the addition of 5% and 25% SFE lupine amounted to 3.21 and 3.04%, respectively. The samples with the addition of SFE lupine oil were characterized by a much smaller increase of TPC compared to refined rapeseed oil without additives (by 6.64%) and a similar increase in comparison to refined rapeseed oil with the addition of TBHQ (by 2.93%). Among the samples heated at 200°C, the samples with the addition of lupine oil had a significantly lower increase of TPC compared to the remaining samples. It should be noted sample with the addition of 25% lupine oil showed lower TPC increase than sample with the addition of 5%. The increase in the content of TAG oxidized monomers in the samples heated at 170°C ranged from 28.45 to 64.94 mg/g of oil and was arranged in the following order: TBHQ < LUP25% < LUP5% < RAF. In the samples heated at 200°C, the increase in the content of TAG oxidized monomers ranged from 47.13 to 125.18 mg/g of oil and was in the following order: LUP25% < LUP5% < TBHQ < RAF.
TAG dimers were found only in samples heated at 200°C. The lowest level was found in samples with the addition of 5 and 25% of lupine oil and it amounted to 5.03 and 2.72 mg/g of oil, respectively. It accounted for 34.79 and 18.81% of dimer content in refined rapeseed oil without additives, respectively.
The research was financed by the UMO-2019/35/N/NZ9/00767 project from the funds of the National Science Centre.