Improvement of sensorial and volatile profiles of olive oil by addition of olive leaves

Abstract

The changes caused by the addition of olive leaves (0, 5, and 10%) during the extraction of olive oil and malaxation time (20, 30, and 30 min) in the volatile profile and sensory attributes of olive oil from cv. Cobrançosa were studied. To investigate such transformations, a central composite designs from the Response Surface Methodology (RSM) was used, retrieving 13 runs combining leaf percentages and malaxation times. Each run was extracted in triplicate (39 olive oils overall). Sensory attributes were improved to leaves addition, mainly green and fruitiness attributes in olfactory and gustatory‐olfactory sensations, but high malaxation times (>30 min) reduced pungent and bitter notes. Leaves addition increased the amounts of total volatiles, particularly the GLV's (green leaves volatiles) (E)‐2‐hexenal, (Z)‐3‐hexenal, and (Z)‐3‐hexenyl acetate, directly correlated with the improved sensory attributes. RSM models a showed positive linear effect with leaves addition, but a negative effect with malaxation time. These results suggest the use of olive leaves as effective odorants for the olive mill industry, while enabling the reduction of malaxation times and by‐product amounts. Practical applications: The results obtained clearly open new lines of research to use olive leaves, a sub‐product of olive oil extraction, in a valuable way. Olive leaves can be used as natural sources of odorants for olive oils. Furthermore, their use during the extraction of olive oils from overmature olives may also lead to an improvement of the volatile fraction and provide enhanced sensory properties to the consumers, thus conferring an added value to these oils. Another important practical application is the extraction process. In our work, we advise to optimize both the percentage of leaves and the malaxation time as much as possible, as they facilitate both sensory and volatile fractions of the extracted olive oils. Sensory attributes are improved to leaves addition, mainly green and fruitiness attributes in olfactory 17 and gustatory‐olfactory sensations, but high malaxation times (> 30 min) reduced pungent and bitter 18 notes. Leaves addition increase the amounts of total volatiles, particularly the GLV's (green leaves 19 volatiles) (E)‐2‐hexenal, (Z)‐3‐hexenal, and (Z)‐3‐hexenyl acetate, directly correlated with the improved 20 sensory attributes. RSM models a show positive linear effect with leaves addition, but a negative effect 21 with malaxation time. These results suggest the use of olive leaves as effective odorants for the olive mill 22 industry, while enabling the reduction of malaxation times and by‐product amounts.

Application of a potentiometric electronic tongue for assessing phenolic and volatile profiles of Arbequina extra virgin olive oils

“…All the samples extractions were carried out in triplicate. The chromatographic analysis was performed on a Shimadzu GC-2010 Plus equipped with a Shimadzu GCMS-QP2010 SE detector (Malheiro et al, 2017(Malheiro et al, , 2013Pinho et al, 2008). A TRB-5MS (30 m × 0.25 mm × 0.25 μm) column (Teknokroma, Spain) was used.…”

Volatile changes in cv. Verdeal Transmontana olive oil: From the drupe to the table, including storage

“…The volatile profile of olives, crushed and malaxed olive pastes, centrifuged and cleaned olives oils, as well as cleaned olive oil at 4, 8 and 12 months after extraction was carried out through HS-SPME (headspace solid phase microextraction) and GC/MS (gas chromatography with mass spectrometry detector) according to the methodology described by Malheiro et al (2017). Briefly, approximately 3 g of whole fruits, 5 g of crushed and malaxed olive paste, and 3 g of olive oil were used for the volatile characterization.…”

“…All analyses were carried out in 50 mL glass vials, spiked with an accurate concentration of internal standard (4-methyl-2-pentanol) and volatiles adsorbed to an SPME fiber coated with divinylbenzene/carbonex/polydimethylsiloxane (DVB/ CAR/PDMS 50/30 μm) (Supelco, Bellefonte, USA). The sampling conditions were determined based on a conjunction of the methodologies presented by Malheiro et al (2017) and Peres et al (2013). The samples were conditioned for 5 min at 30°C for an incisive release of the volatile compounds.…”

Use of Response Surface Methodology (RSM) for the Identification of the Best Extraction Conditions for Headspace Solid‐Phase Micro Extraction (HS‐SPME) of the Volatile Profile of cv. Arbequina Extra‐Virgin Olive Oil

“…This type of fiber has been widely used for determination of volatiles in olive oils, showing good effectiveness and reproducibility and a high affinity for compounds of low and medium molecular weights . The olive oil sample was placed in 50 mL vials to avoid any contact with the fiber and to provide efficient extraction, according to the method used in previous studies . Then, 4‐methyl‐2‐pentanol was added as an internal standard (100 ppm in methanol; 10 µL), and the vials were sealed with a polypropylene cap with a silicon septum.…”

“…[5,24,28] The olive oil sample was placed in 50 mL vials to avoid any contact with the fiber and to provide efficient extraction, according to the method used in previous studies. [29] Then, 4-methyl-2-pentanol was added as an internal standard (100 ppm in methanol; 10 mL), and the vials were sealed with a polypropylene cap with a silicon septum. The volatiles were released at the selected extraction temperature in a water bath and vigorously stirred with a stir bar (350 rpm) for the time required to allow equilibration in the headspace.…”