Comparative assessment of thermal resistance of palm stearin and high oleic blended oil when subjected to frying practice in fast food restaurants

Abstract

In this study, the thermal stability of palm frying oil (palm stearin, POs) and a formulated high oleic frying oil (high oleic blended oil, HOBO) in China was evaluated under simulated frying protocol in fast food restaurants. A series of physico-chemical properties of the oils were measured including change of colour, acid value (AV), peroxide value (PV), p-anisidine value (p-AV), total oxidation (TOTOX=2PV+p-AV), fatty acids composition (FAC), iodine value (IV), carbonyl group value (CGV), total polar compounds (TPC), oxidative stability index (OSI) and vitamin E content. The frying experiments were conducted at 170 ± 5°C for five consecutive days where French fries were fried in five cycles hourly for 12 hr a day. The results indicated that POs gave higher physical and chemical stability than HOBO under extended frying conditions, considering its relatively lower increase in TPC, p-AV, TOTOX and CGV, lesser decrease in C18:2/C16:0 and IV, and longer induction period. Based on the results, it can be conjectured that POs is a more preferred choice for deep fat frying with lower deterioration rate.