Comparative study on volatile compounds, fatty acids, squalene and quality parameters from whole fruit, pulp and seed oils of two tunisian olive cultivars using chemometrics

International audienceThe oils of olive fruits, pulps and seeds from main Tunisian cultivars of olive trees (Chemlali and Oueslati) were extracted at two different indices of maturity. The free acidity, peroxide value, spectrophotometric indices, chlorophyll content, squalene, fatty acids, aroma, and sensory profiles of the oils were analyzed. Fruit and pulp oils are similar in fatty acid compositions, while seed oils have fatty acid profiles that are different from both varieties. For the first time in this work, squalene content in the fruit, pulp, and seed oils was measured by gas chromatography and was found to decrease during maturation. Squalene concentration in the seed oils was lower than that found in fruit and pulp oils. The volatile profiles of twelve Tunisian olive oils obtained from different parts of the fruit were established by solid phase micro-extraction (SPME) coupled with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Sixty-six compounds were identified and characterized, representing 92.4 and 97.6% of the total volatiles. Principal component analysis showed that olive oil quality is strongly affected by olive cultivar, maturity index and the different olive parts. Practical applications: Nowadays, olive oil extraction processes require grinding of whole olives. The proposed method is a useful alternative process for olive oil production that involves olive destoning before extraction of the oil. Although destoning lowers olive oil yields, manufacturing plants for stone removal and milling of pulp have been recently set up, showing good oil yield. Interest in this technology is increasing, and some producers believe that oils obtained from destoned olives are of better quality than oils extracted from the whole fruit. Indeed, oils extracted from destoned olives have better sensory properties than oils obtained from the traditional milling of entire fruits, which is very important from a marketing point of view for olive oil companies