People generally go by sellers' claims on the quality of Omani frankincense. However, a Sultan Qaboos University study has found that there is nothing such as 'high quality' or 'low quality' frankincense – all varieties are equally good and have the same antibacterial properties.
Commonly known as frankincense worldwide and luban in Jebeli and Dhofari Arabic, the resin is an extract of the Boswellia Sacra tree and has various medicinal and aromatherapy applications.
Omani frankincense is commercially available in four grades under the names hoojri, najdi, shathari and shaabi, based on four geographic locations in Dhofar from where the resins are harvested.
“Our study has found that hoojri - the first grade luban - and shaabi – the fourth grade luban - which greatly differed in price, closely resembled each other in essential oil composition, yield and physiochemical characteristics, except colour and texture,” said Dr Hisham Abdul Khader, associate professor of chemistry in the College of Sciences at Sultan Qaboos University.
The market price of the four grades varies considerably according to their colour, clump size and texture. Resin value is determined not only by fragrance but also by colour and clump size, with lighter colours and larger clumps being priced higher.
Hoojri, a first grade resin, which has the lightest colour and a large clump size, is collected from trees in the north of the Samhan mountains in Dhofar, and costs RO32 per kg. Najdi, a second grade resin with a pale yellow colour, is collected from a plateau behind the Dhofar mountains and costs around RO26 per kg.
Shathari, a third grade resin which is darker in colour and collected from the northwest of Dhofar, costs RO12 per kg while shaabi, a fourth grade luban of a darker colour that is collected from valleys, costs RO6 per kg.
Khader said, “As per our study, hoojri, the first grade luban, had the highest oil content of 8.5 per cent whereas the yield of the second and third grade samples - najdi and shathari - were 5.5 and five per cent respectively.
“The oil yield of the fourth grade shaabi was seven per cent, which was higher than that of the second and third grade and closer to that of the first grade, thereby indicating an inconsistency between the oil yield and grade.”
Titled ‘Composition and antibacterial activity of the essential oils of four commercial grades of Omani luban, the oleo gum resin of Boswellia Sacra flueck’, the study also tested frankincense oil for effectiveness of its anti-bacterial properties.
“All four grades were tested for their anti-bacterial properties and showed pronounced activity against a panel of bacteria. The oil killed all the bacteria irrespective of the grade it belonged to, in varying extent. The antibacterial activity of the oils suggests their potential use in food preservation,” Khader said.
“If you go to Salalah, you will notice that the prices are different. The best variety is sold for around RO36 while the lowest grade is sold for RO6. So this study is an eye opener. It will be of use to industries who have so far gone in for the high quality luban. They can now get the same benefits from a less expensive and low quality luban.”
Salim al Saidi, K B Ramesh Kumar, Nallusamy Sivakumar and Salma al Kindy also participated in the study.