ABSTRACT

The objective of the study is to produce oregano flavoured extra virgin olive oil, soybean oil and rosemary flavoured extra virgin olive and soybean oil. The study was also carried out to evaluate the physio-chemical characteristics and the antioxidant capacities of the oil samples.  Flavoured oil samples were produced using dry herbs to prevent water from getting into the oil. The method employed was the hot infusion method. The chemical and physical properties were analysed. From the results obtained it was detected that; the oregano, rosemary extra virgin olive oil samples had higher PV (4.44 to 3.96 meqO2/kg), compared to the oregano, rosemary soybean oil samples (1.20 to 1.17 meq O2/kg. The acid value obtained showed significant difference (p<0.05) among the oil samples with values ranging from (16.73 to 0.28 mg KOH/g). Flavoured oregano, rosemary flavoured soybean oil samples had higher acid value. Rosemary flavoured olive sample had higher iodine value (87.09g iodine/100g) compared to the reference olive oil sample (84.97g iodine/100g). Rosemary flavoured extra virgin olive oil and soybean oil had higher saponification value 297 .13 to 188.83KOH/g compared to the control oil samples 194.85 to 124.53KOH/g which suggested the dominance presence of shorter chains that favour stability. Flavoured olive oil samples had higher FFA value (8.34 to 8.21 %). Higher value of smoke point was recorded in oregano flavoured olive oil. Oregano and rosemary flavoured extra virgin olive oil had higher flash point compared to other flavoured oil samples (370.00˚C to 313.50˚C). The fire point of the oregano and rosemary flavoured extra virgin olive oil and soybean oil ranged from 386˚C to 325 ˚C which implied that the oils were suitable for high temperature heating. GC-MS analysis was carried out and, a total of 15 compounds were identified in the rosemary flavoured olive oil, 23 compounds in the oregano flavoured olive oil, 25 compounds in the oregano flavoured soybean oil, and 14 compounds in the rosemary flavoured soybean oil. The flavoured olive oil samples contained notable concentrations of gamma tocopherol, delta tocopherol, vitamin E, Beta-sitosterol, gamma sitosterol and squalene.