Qualification of the virgin olive oils sold in herbal stores of north of Iran

Olive oil has a lot of nutritional and medicinal benefits, which make it more valuable than other oils. Therefore, it is noticeable for adulteration by mixing with the cheaper oils. At this study, authenticity of virgin olive oils sold in herbal stores in north of Iran (Rasht) has been investigated.

During 2019, 26 samples of virgin olive oils were collected randomly from the herbal stores of Rasht city (Guilan, north of Iran). Fatty acid profile by gas chromatograph, peroxide value by calculation of milliequivalent of active oxygen per kilogram of oil, and acidity by titration of the samples with potassium hydroxide were determined in the laboratory and compared to the national regulation.

Approximately, 58% of the samples were out of the permitted range at least in one of the measured parameters. With regard to fatty acid profile, 77% of the samples were within the normal range. Predominant fatty acids were included to oleic acid (59.8 ±14.3%), linoleic acid (21.4 ±14.1%), palmitic acid (13.8 ±1.4%), stearic acid (2.7 ±0.8%), and palmitoleic acid (0.7 ±0.3%). In case of peroxide value, 92.3% of the samples were within the acceptable range. Based on acidity, different virgin olive oils were differentiated as extra virgin (n = 1, %3.8), first grade virgin (n = 11, 42.31%), ordinary virgin (n = 8, %30.77), and lampante virgin (n = 6, %23.08). Our investigation revealed that the olive oils sold in herbal stores as traditional market should be monitored restrictedly to assess their originality and storage condition. Although, they should be examined periodically to find any adulteration, if exists.