Qualitative parameters and deterioration kinetics of palm oil, shea butter and their blend use for frying cheese

Abstract

Studies on the effect of deep frying of oils and their blend in specified frying cycles is unavailable in the open scientific literature. Thus, we investigated fluctuations in the quality of palm oil, shea butter, and their blend as affected by repeated usage in deep-frying of cheese. Crude palm oil, shea butter, and their blend (1:1 w/w) were subjected to deep frying of cheese at 150 °C for 15 minutes, repeated eight times, repeated for six (6) consecutive days. These oil quality indices such as free fatty acid (FFA), peroxide value, p-anisidine value, color index, iodine value, acid value, saponification value, specific gravity and refractive index changes in oil quality were determined. Kinetic rate and Arrhenius equation were used to determine deterioration rate and activation energy. Data were analyzed using ANOVA and regression at α= = 0.05. The FFA values of palm oil (6.09 - 8.03%), shea butter (2.12 - 2.91%), and their blend rate (3.30 - 4.50%) increased significantly (p < 0.05). Palm oil recorded a high value of peroxide (6.20 meqO2/kg), while the lowest value was recorded by shea butter (3.20 meqO2/kg). The p-anisidine value of palm oil was higher (91.77%) after the sixth frying cycle than shea butter (11.00%) and their blend (46.17%). A slight difference in iodine value was observed in the blend (4.89 - 3.82%), while a significant decrease (4.73 g − 0.90 g) was observed in palm oil. A high smoke point was recorded for shea butter (222.7 °C and 226.4°C), palm oil (204.3 °C and 218.2°C) and the blend oil (212.2 °C and 216.6°C) within the six frying cycles. The study indicated that the oils and their blend can be repeatedly used for six frying cycles of deep fat frying of cheese since all the quality parameters fall within the range recommended by the Codex Alimentarius Commission for edible oil. Blend oil exhibited best stability during repeated deep-frying while shea butter and palm oil were considerably less stable.