Fatty acid methyl and ethyl esters as well as wax esters for evaluating the quality of olive oils

Abstract

A promising correlation between chemical analysis and sensorial evaluation was conWrmed: extra virgin olive oils with low contents of methyl and ethyl esters of fatty acids as well as straight chain wax esters were sensorially evaluated as being of high quality, whereas some with high contents were even devaluated as not being of extra virgin quality. Methanol and ethanol formed during fermentation in degrading olives are esteriWed, largely by transesteriWcation with fatty acids from the triglycerides, and in this way transferred into the pressed oil. The presence of high contents of methyl and ethyl esters in degrading olives was conWrmed. Wax esters from the skin of the olives are extracted at low yields, whereby the yield increases when the olives are soft and possibly degrading. High wax ester contents may, therefore, stand for mild oils, but also for deWcient oils.

Quality and chemical profiles of monovarietal north Moroccan olive oils from “Picholine Marocaine” cultivar: Registration database development and geographical discrimination

“…They are useful indicators for determining the quality of olives and the oil produced from them, as they are direct indicators of degradation. Indeed, they result from the degradation and fermentation processes of low quality processed olive fruits (Biedermann, Bongartz, Mariani, & Grob, 2008). During the period in which the current study was carried out, the legal limit of this parameter for the Extra VOO was established as sum of FAME and FAEE ≤75 mg/kg or between 75 and 150 mg/kg if the FAEE/FAME ratio is <1.5 (IOC, 2012).…”

How ‘ground‐picked’ olive fruits affect virgin olive oil ethanol content, ethyl esters and quality

“…Nowadays, because of the recent adoption of ethyl ester as a quality parameter to distinguish ‘extra’ virgin olive oils it is essential to describe whether this parameter is affected by the bad practices described above. Ethyl esters have been related to low‐quality VOOs and were associated with oils from damaged and low‐quality olive fruits . Conte et al described the formation of ethyl esters during oil conservation.…”

“…Conte et al described the formation of ethyl esters during oil conservation. Ethyl esters can be formed by direct esterification of free fatty acids or by transesterification of fatty acids from triacylglycerides as described by Biedermann et al Their alcoholic precursor – ethanol – may be synthesized in the own olive fruit whereas it remains on the tree, but any alteration of the fruit can result in fruit enzyme activation or attack by microorganisms because of the loss of fruit integrity during its period on the ground. Furthermore, an increase in ethanol content and free acidity, although values were always below the regulated limits, may induce the synthesis of ethyl esters in VOO.…”

Phytol and Phytyl Fatty Acid Esters: Occurrence, Concentrations, and Relevance

“…Accordingly, PFAE levels were high when geranylgeranyl fatty acid ester levels were low and vice versa . In the case of olive oil, PFAE and geranylgeranyl fatty acid esters were rather present in the olive oil extracted from the pulp than from the skin of the fruits . Concentrations of PFAE in olive oil extracted from the whole fruits ranged from 13 to 455 mg kg −1 for unsaturated phy‐18:X and from 2.1 to 77 mg kg −1 for phy‐20:0 whereas the ratio of phy‐18:X/phy‐20:0 and phy‐18:X/phy‐22:0 was rather constant .…”