Title : Chemical analysis directing strategic planning for producing high quality olive oil- case study
Abstract:
Due to the economic value and health impact of olive oil, many non-Mediterranean countries are trying to cultivate olive trees. However, this is challenging, as the proper climate condition play an important role in producing olive that has a high quality oil. Oman is one of the Arab Gulf countries that started cultivating olives about two decades ago in Jabal AL Akhadar (JA). JA is located at an altitude of 2000-3000 m above sea level and the climate there is similar to the Mediterranean countries. The relative humidity in 2023 ranged from 30.7% to 67.9%, and the range of air and ground temperature was (7.4 - 23.0)°C and (7.9 -23.7)°C respectively. Today the total number of olive trees is more than 25000, distributed on little more than 36 hectares of land. The cultivars used are originated from various countries such Greece, Croatia, Egypt, Portugal and Spain. In 2019, about sixty tons of olives were harvested from which about 8,000?liters of oil were produced. The Sultanate of Oman government is planning to expand olive growing in JA by introducing suitable cultivars with high quality oil. However, it is well established that part of the health impact of olive oil is due to the richness in phenolic compounds. It is also known, that olive oil contains some specific phenolic compound that have therapeutic effect such as oleocanthal, oleocanthal, hydroxytyrosol and tyrosol (OHTs). On the other hand, the concentration of all phenolic compounds in olive oil is significantly affected by climate, soil and environment conditions. In this project, we are aiming to evaluate various types of olive oils produced in JA in terms of the concentration of OHTs. This will help in directing the production toward the best type of olive oil in terms of economic and health impact.
Six varieties of olive oil samples were evaluated and analysed. These varieties are Arbequina, Picual, Carotina, Kalamata, Karonaki, and Dolce. These varieties were selected because of the good oil yield. All oil samples were collected from a governmental farm called Riyad Al Jabal. This farm is under the administration of the Royal Court Affair, Sultanate of Oman. The olive trees in this farm were planted in January 2010 and treated similarly. The olive from each variety was collected at an appropriate time with 50% maturity. After the extraction process, the sample was transferred to SQU and stored in darkness. The analysis of the samples was done within 15 days to ensure the freshness of the analyzed samples. Initially, routine analysis was conducted such as the content of free fatty acids and peroxide value. All oils varaieties were below the the allowable limits. The analysis of the extracted oil was further carried out using HPLC and LC-MS/MS technique for quantitative determination of OHTs. The method showed strong linear relationships the peak area and the concentration of the analytes. The correlation coefficients between 0.978 and 0.999, indicating its reliability for quantifying the targeted compounds. The result revealed that certain olive oil varieties like Carotina (180.1 ± 0.1) mg per kg-1, Kalamata (138.44± 0.09) mg per kg-1 and Picual (107.7± 0.3) mg per kg-1 exhibit higher total concentration of OHTs, making them favorable choices for cultivation in JA. In addition, the Folin-Ciocalteu reagent method was utilized in the study to estimate the total phenolic content of olive oil extracts using gallic acid as tandard. Results indicated varying levels of phenolic compounds among different olive oil varieties, with Picual (254.6± 6.1) mg per kg-1 and Carotina (240.6± 5.6) mg per kg-1 demonstrating the highest content. Based on these finding, the Government distributed 200 seedlings of the selected varieties aiming to produce a higher quality of olive oil.
Audience Take Away:
- Chemical analysis can be utilized for directing strategic planning
- The olive oil quality varies significantly from variety to another depending on genetics and environmental conditions
- Determination of total phenolic content is an important parameter that should be added to the standard parameters of checking the quality of olive oil
