A study on monitoring of frying performance and oxidative stability of virgin coconut oil (VCO) during continuous/prolonged deep fat frying process using chemical and FTIR spectroscopy

J Food Sci Technol. 2015 Feb;52(2):984-91. doi: 10.1007/s13197-013-1078-8. Epub 2013 Jul 4.


The performance or quality of the Virgin coconut oil (VCO) during continuous/prolonged deep fat frying of soaked bengal gram dhal was evaluated at 180 °C ± 5 °C for 8 h with the help of physico-chemical and rheological parameters. Chemical changes indicated that the free fatty acid (FFA) content and TBA increased significantly (p ≤ 0.05) from 0.11 to 0.98 % lauric acid and 0.06 to 0.61 malonaldehyde/kg of oil respectively. Initially, the peroxide value (PV) of VCO sample was 3.25 meqO2/kg which increased to 9.12 meqO2/kg after 6 h of frying but at the end of frying the value of PV was again found to decrease (8.01 meqO2/kg). The regression coefficients (R(2)) between CD232, CT270 and frying time were 0.964 and 0.983 respectively. The L*, a* and b* colour values measured on the CIELAB colour scale showed a decrease in L* and increase in a*, b* values after 8 h of continuous frying. The p-AV and total polar compounds were increased significantly (p ≤ 0.05) from 2.41 to 17.93 and 2.77 to 8.14 % respectively. Initially, the viscosity of VCO was 49.87cp which increased to 69.87cp after 8 h of continuous frying. The FTIR spectra justify that VCO samples after 8 h of frying found to be stable and acceptable as there was no change occurred at 1,739 cm(-1) frequency which mainly corresponded to carbonylic compounds resulted from the hydroperoxide decompositions after 8 h of continuous frying.

Keywords: FTIR; Peroxide value (PV); Specific absorptivity; Total polar compounds; Virgin coconut oil (VCO); Viscosity.