Early Harvest Effects on Hydrophilic Phenolic Components of Extra Virgin Olive Oils Cvs. ‘Ayvalık’, ‘Memecik’ and ‘Topakaşı’

Abstract

The study was conducted to determine the effects of cultivar, harvest period and their interaction on the hydrophilic phenolic components extra virgin olive oils of the cultivars ‘Ayvalık’, ‘Memecik’ and ‘Topakaşı’. Olives were collected at three different harvesting periods; (1) early harvest period-1 (Beginning of spotting), (2) early harvest period-2 (End of spotting), and (3) optimum harvest period. Oils were extracted using an abencor system. HPLC (High-performance liquid chromatograph) technique was used to quantify The phenolic compounds including: tyrosol (p-HPEA), hydroxytyrosol (3,4-DHPEA), luteolin, rutin, quercetin, catechin, sinapinic acid, p-coumaric acid, cinnamic acid, vanillin, vanillic acid, ferulic acid and gallic acid were quantified using HPLC. The results indicated that the effects of harvest period on the phenolic components were variety dependent. At the early harvest period-1, ‘Memecik’ and ‘Topakaşı’ had the highest efficiency in luteolin, cinnamic acid, vanillic acid, and ferulic acid contents, while ‘Ayvalık’ had the highest efficiency in hydroxytyrosol, sinapinic acid, p-coumaric, vanillin and ferulic acid contents. At the optimum harvest period, ‘Ayvalık’ had the highest efficiency in luteolin, tyrosol and gallic acid contents, while ‘Topakaşı’ had the highest efficiency in tyrosol, hydroxytyrosol and rutin content. The highest phenolic content was detected in the early harvest period-1. The content of tyrosol linearly increased with the progress of maturity harvest period, whereas the contents of the sinapinic acid, vanillin, vanilic acid and ferulic acid decreased. The oils of ‘Memecik’ variety had significantly higher phenolic content than those of ‘Ayvalık’ and ‘Topakaşı’ varieties.

Full text

Vol.:(0123456789)
Biochemical Genetics (2020) 58:981–992
https://doi.org/10.1007/s10528-020-10008-9
1 3
ORIGINAL ARTICLE
Early Harvest Eects onHydrophilic Phenolic Components
ofExtra Virgin Olive Oils Cvs. ‘Ayvalık’, ‘Memecik’
and‘Topakaşı’
FatmaYıldırım, etal.[full author details at the end of the article]
Received: 17 October 2019 / Accepted: 16 October 2020 / Published online: 23 November 2020
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
The study was conducted to determine the effects of cultivar, harvest period and
their interaction on the hydrophilic phenolic components extra virgin olive oils of
the cultivars ‘Ayvalık’, ‘Memecik’ and ‘Topakaşı’. Olives were collected at three
different harvesting periods; (1) early harvest period-1 (Beginning of spotting),
(2) early harvest period-2 (End of spotting), and (3) optimum harvest period. Oils
were extracted using an abencor system. HPLC (High-performance liquid chroma-
tograph) technique was used to quantify The phenolic compounds including: tyro-
sol (p-HPEA), hydroxytyrosol (3,4-DHPEA), luteolin, rutin, quercetin, catechin,
sinapinic acid, p-coumaric acid, cinnamic acid, vanillin, vanillic acid, ferulic acid
and gallic acid were quantified using HPLC. The results indicated that the effects
of harvest period on the phenolic components were variety dependent. At the early
harvest period-1, ‘Memecik’ and ‘Topakaşı’ had the highest efficiency in luteolin,
cinnamic acid, vanillic acid, and ferulic acid contents, while ‘Ayvalık’ had the high-
est efficiency in hydroxytyrosol, sinapinic acid, p-coumaric, vanillin and ferulic acid
contents. At the optimum harvest period, ‘Ayvalık’ had the highest efficiency in lute-
olin, tyrosol and gallic acid contents, while ‘Topakaşı’ had the highest efficiency in
tyrosol, hydroxytyrosol and rutin content. The highest phenolic content was detected
in the early harvest period-1. The content of tyrosol linearly increased with the pro-
gress of maturity harvest period, whereas the contents of the sinapinic acid, vanillin,
vanilic acid and ferulic acid decreased. The oils of ‘Memecik’ variety had signifi-
cantly higher phenolic content than those of ‘Ayvalık’ and ‘Topakaşı’ varieties.
Keywords Olive oil· Phenolic· Cultivars· Maturity stage· Tyrosol·
Hydroxytyrosol
This article is a revised version of this article [1] published in Biochemical Genetics that has been
retracted. [1] Yıldırım, F., Yıldırım, A.N., Özkan, G. etal. Biochem Genet (2016). https ://doi.
org/10.1007/s1052 8-016-9784-3.

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Introduction
Olive (Olea europaea L.), the typical tree of the Mediterranean basin, is an
important source of nutrients, particularly a source of oil. The fresh olive fruit
generally contains 40–60% water and 15–35% oil. A significant amount of the oil
contained in olive is found in emulsion with the available water in the fruit flesh
(the mesocarp). The extra virgin olive oil obtained by crushing and squeezing the
olive fruit (including the seed) is one of the plant oils which can be consumed in
crude form without being refined and has a unique fruit-like taste and aroma. The
extra virgin olive oil is also quite valuable since it contains many biochemicals
beneficial to human health which prevent many diseases such as cardiovascular
diseases and cancer. These positive effects of olive oil on health are attributed
to the synergic effect of monounsaturated fatty acids (oleic acid) and of strong
antioxidants (phenolic substances in particular) that it contains (Oktar etal. 1983;
Ryan and Robards 1998; Salvador etal. 2003).
Virgin olive oil contains a considerable amount of phenols. The rational
amount of phenols in oil directly affects the eating quality, oxidative stability,
and shelf life of olive oil. The phenolic compounds can be divided into lipophilic
(such as tocopherols) and hydrophilic. The primary hydrophilic phenolics found
in olive are phenolic acids, phenolic alcohols, flavonoids, and secoiridoids. Tyro-
sol [4-(2-Hydroxyethyl)phenol] and hydroxytyrosol [4-(2-Hydroxyethyl)-1,2-ben-
zenediol] resulting from the hydrolysis of oleuropein and ligstrosit are the most
characteristic phenolic components of olive oil, and the free forms of tyrosol
and hydroxytyrosol and their secoiridoid derivatives constitute about 30% of the
total phenolics (Servili etal. 2004). Besides, lignans (1-acetoxypinoresinol and
pinoresinol) as well as luteolin and apigenin flavonoids were identified in olive
oil (Owen etal. 2000; Garcia etal. 2002). The phenolic compound present in the
olive oil have positive effects on some physiological parameters, such as plasma
lipoproteins, oxidative damage, inflammatory markers, platelet and cellular func-
tion, antimicrobial activity and bone health (Cicerale etal. 2010). Covas etal.
(2006) reported that the phenolics contained in olive oil could be beneficial to the
plasma lipid level and oxidative damage. It has also been shown that the hydroxy-
tyrosol which is the main phenolics in the olive oil functions as antioxidant (Ser-
vili and Montedoro 2002), prevents protein damage (D’Angelo etal. 2005), and
correlates with the oxidative stability of virgin olive oil (Baldioli etal. 1996).
Additionally, tyrosol is a natural phenolic antioxidant (Giovannini etal. 1999).
The contents of phenolic substances in olive oil are quite affected by the geno-
type, the geographical region in which olive is cultivated and its ecological condi-
tions, cultural practices, harvest time, and the oil extraction method (Mousa etal.
1996; Beltran etal. 2005; Ayton etal. 2006; Servili et al. 2007; Keceli 2013).
The harvest time, especially early period, is one of the most important factors
affecting the content of phenolics. Studies have demonstrated that the total phe-
nolic contents of the oils obtained from the olives, harvested earlier are higher.
Skevin etal. (2003) also reported that with an increase in fruit maturity, the total
phenolic content decreased and the phenolic content varied depending on the

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cultivar. Therefore, the choice of a proper harvest period is essential to obtain a
high quality virgin olive oil with a high phenolic content. Morover Rotondi etal.
(2004), reported that the maturity stage of 2.5–3.5 was the most appropriate stage
for olive cultivar ‘Nostrana di Brisighella’, cultivated in the central northern Ital-
ian region. Although there is much knowledge about the total phenolic content
of virgin olive oil, very little information is available as regards to the individual
behaviors of phenolic components during different maturity stages. The quantifi-
cation of individual phenolic components in olive oil according to harvest time
and cultivar has not yet been evaluated. In order to recommend the proper early
harvest time to olive growers it is necessary to determine the efficacy of cultivar
on the main phenolic components, especially hydroxytyrosol, which give bitter
and pungent taste of extra virgin olive oil.
In Turkey, the olives for oil production are generally harvested in November and
December. Moreover, early harvesting is performed for olive oil in October and
November as well. Therefore, the phenolic components of the oil obtained from the
olives harvested in the early period will be an important criteria to harvest a high
quality olive which is beneficial for healthy nutrition and marketing. The objective
of this study was to determine the variation in the hydrophilic phenolic components
of the olive oils obtained from the olives harvested at three different stages of ripe-
ness: (1) early harvest period-1 (green skin with pink spots in less than half of the
fruit. Beginning of spotting), (2) early harvest period-2 (pink or purple skin in more
than half of the fruit. End of spotting) and (3) optimum harvest period (black skin,
less than half of pulp to be purple) of the three olive cultivars cultivated under the
same culturing conditions in the geographical region of Sutculer, Isparta in the
Mediterranean Region of Turkey.
Materials andMethods
Materials
This study was conducted in the laboratories of the Department of Horticulture in
the Faculty of Agriculture and of the Department of Food Engineering in the Fac-
ulty of Engineering at Suleyman Demirel University in the growing season of 2011.
The study was conducted in the geographical region of Sutculer, Isparta (37°
29′40″ N 30° 58′54″ E) in the Mediterranean Region of Turkey. The altitude of
the region is 250 m. The region is located within the triangle of the south-west-
ern, north-eastern, and south-eastern parts of the Western Taurus Mountains, has a
mountainous geographical nature, and is under the influence of the Mediterranean
climate.
The study included the cultivars ‘Ayvalık’, ‘Memecik’, and ‘Topakaşı’, grafted
on the seedling rootstock, treated with the same cultural treatments (e.g. irrigation,
fertilization, and pruning), and cultivated under commercial orchard conditions. The
trees are 10 years old, and the orchard is located at an altitude of 250 m. While
the cultivars ‘Ayvalık’ and ‘Memecik’ are cultivated in a wide geographical area

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throughout Turkey, the cultivar ‘Topakaşı’ is only locally available in a narrow area
in the regions of Sutculer, Anamur, and Tarsus.
Methods
The fruit samples were collected at the three different maturity stages based on the
fruit skin and fruit flesh coloration. The fruits were harvested by hand. This method
is believed to be more suitable for such an investigation since fruits with different
colors are known to be chemically distinct, particularly with respect to phenolic
compounds (Bouaziz etal. 2004). The samples were immediately brought to the lab-
oratory by means of large-volume vacuum flasks cooled with ice packs.
Extra Virgin Olive Oil Extraction
Oil extraction was carried out by using a two-phase vertical centrifuge (suitable for
the laboratory). Anhydrous sodium sulfate was used to eliminate the moisture which
remained in the oil and caused turbidity following centrifugation and filtration. The
natural extra virgin olive oils obtained were placed into dark colored glass bottles
and preserved at −80°C until analysis.
Phenolics Analysis
The phenolic substances extracted from the oil for three times with the
water:methanol (60:40, v/v) mixture were filtered through a micropore filter
(0.45μm) and injected into the high performance liquid chromatography (HPLC-
Shimadzu). To determine the profile of the phenolic substances, the studies were
carried out according to the modified gradient elution program of Caponio etal.
(1999) (Table1). A 3% solution of acetic acid in water (Solvent A) was used in
Table 1 The linear solvent
gradient system used in HPLC
analysis of phenolics
Time (min) 3% Acetic acid (%) Methanol (%)
0.10 93 7
20.0 72 28
28.0 75 25
35.0 70 30
50.0 70 30
60.0 67 33
62.0 58 42
70.0 50 50
73.0 30 70
75.0 20 80
80.0 0 100
81.0 93 7

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the mobile phase in the gradient elution profile and Methanol (Solvent B) solu-
tions were used in the HPLC. Hydroxytyrosol, tyrosol, oleuropein, rutin, luteo-
lin, quercetin, vanillin, cinnamic acid, gallic acid, chlorogenic acid, vanillic acid,
sinapinic acid, p-coumaric acid and ferulic acid were used as the standards of
phenolic substances (Fig.1). The analyses were repeated three times.
HPLC conditions were as shown below:
Detector: SPD-M10Avp diode array detector (λmax = 278nm).
Auto sampler: SIL-10AD vp.
System controller: SCL-10Avp.
Pump system: LC-10AD vp.
Degassor: DGU-14A.
Colon oven: CTO-10 Avp.
Colon: Agilent Eclipse XDB C18 (250 × 4.60mm) 5μ.
Mobil phase: Solvent A (acetic acid 3%), solvent B (methanol).
Flow rate: 0.8mL/min.
Temperature: 30°C.
Injection volume: 20μL.
The data were subjected to the one-way analysis of variance (Anova), and the
means were separated using Duncan’s Multiple Range Test at the 5% level of
significance.
Fig. 1 HPLC chromatograms of phenolic standards. 1 gallic acid, 2 hydroxytyrosol, 3 tyrosol, 4 chloro-
genic acid, 5 vanillic acid, 6 syringic acid, 7 vanillin, 8 p-coumaric acid, 9 ferulic acid, 10 sinapinic acid,
11 o-coumaric acid, 12 rutin, 13 oleuropein, 14 cinnamic acid, 15 quercetin, 16 luteolin

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Results andDiscussion
Such factors as cultivar, harvest time, and cultural treatments like irrigation as
well as the extraction and processing technology may affect the phenolic com-
pounds in olive oil. The results indicated that the interaction harvest time x cul-
tivar was significant (p < 0.001) (Table 2). While luteolin, tyrosol, hydroxytyro-
sol, sinapinic acid, p-coumaric acid, cinnamic acid, vanillin, vanillic acid, ferulic
acid, gallic acid and rutin were found in the oil samples, chlorogenic acid, ole-
uropein, syringic acid, o-coumaric acid or quercetin was not detected (Table2,
Fig.2). These compounds were characterized in many previous studies carried
out in different regions (Servili and Montedoro 2002; Garcia etal. 2001; Oca-
koglu etal. 2009). Tyrosol, hydroxytyrosol and luteolin were found as the main
phenolic components.
Likewise, the previous studies reported that tyrosol and hydroxytyrosol were
the characteristic phenolic alcohols of olive oil (Ocakoglu etal. 2009; Tuck and
Hayball 2002; Vinha etal. 2005; Kayahan and Tekin 2006; Jimenez etal. 2013).
Tyrosol and hydroxytyrosol are phenylethanoids—a type of phenolic com-
pound characterized by a phenethyl alcohol structure (D’Angelo etal. 2005). It
was found that these compounds in olive oil were in the form of elenolic acid—
an ester of oleuropein. The tyrosol content varied between 1.09 and 3.50mg/kg.
These values were rather lower than the findings by Monaco etal. (2015), rela-
tively lower than the findings by Jimenez etal. (2013) and Bengana etal. (2013),
but relatively higher than the findings by Konuşkan (2008). In the study, the tyro-
sol content increased with the progress of maturity and the highest tyrosol con-
tent in all three cultivars was detected in the optimum harvest period (Fig.1).
Similar findings were also reported by Garcia etal. (2002). On the contrary, Jime-
nez etal. (2013) and Bengana etal. (2013) demonstrated that the tyrosol content
decreased as maturity progressed. The tyrosol content significantly varied among
cultivars and was the highest in ‘Memecik’ (3.38mg/kg on average).
The hydroxytyrosol contents of the olive oils ranged from 0.87 to 1.81mg/kg.
These values were quite higher than the findings by Yousfi etal. (2006), similar
to the findings by Monaco etal. (2015) and Konuşkan (2008), but relatively lower
than the findings by Jimenez etal. (2013), and rather lower than the findings by
Bengana etal. (2013). The highest hydroxytyrosol content was detected in the
early harvest period-1 for ‘Ayvalık’ and ‘Memecik’ but at the optimum harvest
period for ‘Topakaşı’.
The hydroxytyrosol content displayed a fluctuating trend for ‘Ayvalık’ and
‘Topakaşı’ with the harvest periods, whereas it decreased with the progress of
maturity for ‘Memecik’ Jimenez etal. (2013) also reported that the hydroxytyro-
sol content decreased as maturity progressed in the cultivar ‘Picudo’. The highest
hydroxytyrosol content (1.28mg/kg) was recorded in ‘Topakaşı’. In this study,
the tyrosol content was found to be higher than the hydroxytyrosol content, which
was in agreement with the literature (Monaco etal. 2015; Bengana etal. 2013).
Luteolin is a flavone—a type of flavonoid with potential for cancer prevention
(Lin etal. 2008). The luteolin content was in the range of 1.49 to 3.98mg/kg

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Table 2 Effect of the maturity stage on the phenolic contents of cvs.‘Ayvalık’, ‘Memecik’ and ‘Topakaşı’
virgin olive oil (mg/kg)
Cultivars Early harvest time 1 Early harvest time 2 Optimum harvest
time
Average
Luteolin
Ayvalık 1.51c*C** 2.06bB 3.57aA 2.38
Memecik 3.98aA 2.42aB 2.42bB 2.94
Topakaşı 2.82bA 1.71cB 1.49cC 2.00
Tyrosol
Ayvalık 1.49bB 1.40bC 1.68bA 1.52
Memecik 3.25aC 3.40aB 3.50aA 3.38
Topakaşı 1.09cC 1.20cB 1.36cA 1.22
Hydroxytyrosol
Ayvalık 1.16aA 1.08aC 1.14bB 1.12
Memecik 1.06bA 1.03bB 0.94cC 1.01
Topakaşı 1.17aB 0.87cC 1.81aA 1.28
Sinapinic acid
Ayvalık 0.93cA 0.56cB 0.37cC 0.62
Memecik 2.02aB 2.14aA 1.18aC 1.78
Topakaşı 1.68bA 1.22bB 0.52bC 1.14
p-Coumaric acid
Ayvalık 0.37bA 0.32bB 0.14cC 0.28
Memecik 2.22aB 2.26aA 2.13aC 2.20
Topakaşı 0.27cB 0.24cC 0.51bA 0.34
Cinnamic acid
Ayvalık 0.53bB 0.69aA 0.28bC 0.50
Memecik 1.59aA 0.52bC 1.46aB 1.19
Topakaşı 0.22cA 0.17cB 0.12cC 0.17
Vanillin
Ayvalık 0.68bA 0.58bB 0.34cC 0.53
Memecik 0.34cC 0.39cA 0.37bB 0.37
Topakaşı 1.04aA 1.02aB 0.45aC 0.84
Vanillic acid
Ayvalık 0.35cB 0.32cC 0.36bA 0.34
Memecik 0.57aA 0.43aB 0.37aC 0.45
Topakaşı 0.44bA 0.37bB 0.33cC 0.34
Ferulic acid
Ayvalık 0.08cA 0.07cB 0.07cB 0.07
Memecik 0.35aA 0.34aB 0.30aC 0.33
Topakaşı 0.11bA 0.08bB 0.08bB 0.09
Gallic acid
Ayvalık 0.06bC 0.08bB 0.15bA 0.09
Memecik 0.30aA 0.27aC 0.28aB 0.28
Topakaşı nd nd nd nd

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in the study. These values were similar to the findings of Bengana etal. (2013),
while they were quite higher as compared with the findings of Konuşkan (2008)
and relatively lower in comparison with the findings of Jimenez et al. (2013).
The luteolin content increased with the progress of maturity for ‘Ayvalık’ but
decreased for Topakaşı’. It displayed some decrease with the progress of matu-
rity for ‘Memecik’, and this decrease remained constant in the optimum stage
of maturity. These results show that there is no linear relationship between the
luteolin content and maturity. Likewise, different results were also reported in
the literature. Yousfi etal. (2006), reported that the luteolin content increased as
maturation progressed, but Garcia etal. (2002), reported that the luteolin con-
tent decreased with the progress of maturity, while Jimenez et al. (2013) and
Konuşkan (2008) obtained variable results during the process of maturity. A
significant difference in the luteolin content was observed among the cultivars.
The highest luteolin content (2.94mg/kg) was found in ‘Memecik’, followed by
‘Ayvalık’ (2.38mg/kg). The results of the study were in agreement with the find-
ings by Ocakoglu etal. (2009). In addition, Ocakoglu et al. (2009) determined
that ‘Memecik’, which they had examined for two years, contained more luteolin
Table 2 (continued)
Cultivars Early harvest time 1 Early harvest time 2 Optimum harvest
time
Average
Rutin
Ayvalık nd nd nd nd
Memecik nd nd nd nd
Topakaşı 0.14C 0.16B 0.34A 0.21
nd Not detected
* Lowercase letters indicate the statistical difference within same column at the 5% level
** Uppercase letters indicate the statistical difference within same line at the 5% level
Fig. 2 HPLC chromatograms of fruit extracts in early harvest period-2 (skin pink or purple in more than
half of the fruit. End of spotting) of ‘Memecik’ cultivar

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as compared to the other cultivars. On the other hand, rutin, another flavonoid,
was only recorded in ‘Topakaşı’ and the rutin content increased with an increase
in maturity in the study.
The phenolic acids first found in olive oil are caffeic acid, vanillic acid, syrin-
gic acid, p-coumaric acid, o-coumaric acid, protocatechuic acid, sinapinic acid, and
p-hydroxybenzoic acid (Servili and Montedoro 2002). In this study, the sinapinic
acid ranged from 0.37 to 2.14mg/kg. Jimenez etal. (2013) could not determine any
sinapinic acid in the oils of the cultivar ‘Picudo’. In the study, it was established that
the sinapinic acid content gradually decreased with an increase in maturity in all
three cultivars. The lowest sinapinic acid content was recorded in the optimum har-
vest period, when the fruits were the most mature. The highest sinapinic acid con-
tent was determined in ‘Memecik’ (1.78mg/kg on average), followed by ‘Topakaşı’
(1.14mg/kg on average).
The p-coumaric acid content varied between 0.14 and 2.26mg/kg in the study.
Similarly, Monaco etal. (2015) also detected 0.02 to 1.10mg/kg of p-coumaric acid
content in the oils of different olive cultivars. The p-coumaric acid content decreased
in the optimum harvest period for ‘Ayvalık’ and ‘Memecik’ but increased for
‘Topakaşı’ (Table2). The highest p-coumaric acid content (2.20mg/kg) was found
in ‘Memecik’, whereas the lowest value (0.28mg/kg) was determined in ‘Ayvalık’.
The cinnamic acid content ranged from 0.12 to 1.59mg/kg. Similarly, Ocakoglu
etal. (2009) determined that the cinnamic acid contents of some Turkish olive cul-
tivars were between 0.02 and 2.55mg/kg. The highest cinnamic acid content was
detected in the early harvest period-2 for ‘Ayvalık’ but the lowest value in the opti-
mum harvest period. The highest cinnamic acid content was determined in the early
harvest period-1 for ‘Memecik’, but the lowest value in the early harvest period-2.
On the other hand, ‘Topakaşı’ showed some decrease with the progress of matu-
rity in the cinnamic acid content. ‘Memecik’ (1.19mg/kg) was the cultivar with the
highest cinnamic acid content, followed by ‘Ayvalık’ (0.50mg/kg). Ocakoğlu etal.
(2009) also reported that the cinnamic acid content ranged from 0.53 to 0.97mg/kg
for ‘Memecik’ but from 0.00 to 0.04mg/kg for ‘Ayvalık’.
In the study, the vanillin content varied between 0.32 and 1.04 mg/kg. These
values were higher than the findings by Jimenez etal. (2013) and Ocakoğlu etal.
(2009). The vanillin content decreased significantly with the progress of maturity for
‘Ayvalık’ and ‘Topakaşı’. However, an increase in the vanillin content was recorded
for ‘Memecik’ with maturity. In the study, the highest vanillin content (0.84mg/
kg) was detected in ‘Topakaşı’ but the lowest vanillin content (0.37 mg/kg) in
‘Memecik’. In support of our findings Jimenez etal. (2013) also reported that the
vanillin content decreased with the progress of maturity.
In the study, the vanillic acid content ranged from 0.32 to 0.57mg/kg. These val-
ues were similar to the findings of Jimenez etal. (2013) and Ocakoğlu etal. (2009).
The vanillic acid content decreased with the progress of maturity for ‘Memecik’ and
‘Topakaşı’. In the cv. ‘Ayvalık’, a decrease in the vanillic acid content was observed
in the early harvest period-2, but it increased again in the optimum harvest period.
Unlike our findings, Jimenez etal. (2013) reported that there was neither a decrease
nor an increase in the vanillic acid content with the maturity. In the study, the high-
est vanillic acid content was found in ‘Memecik’ (0.45 mg/kg). Ocakoğlu et al.

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(2009) reported that the vanillic acid content varied between 0.07 and 0.12mg/kg in
‘Memecik’ but between 0.13 and 0.72mg/kg in ‘Ayvalık’.
The ferulic acid content ranged from 0.07 to 0.35mg/kg in the study. These val-
ues were similar to the findings of Ocakoğlu etal. (2009). Nevertheless, they were
higher than the findings of Jimenez etal. (2013). In the study, the highest ferulic
acid content in all three cultivars was detected in the early harvest period-1 and it
decreased with the progress of maturity. The highest ferulic acid content (0.33mg/
kg) was detected in ‘Memecik’. Jimenez etal. (2013) indicated that ‘Picudo’ olive
oils obtained from the olives harvested in the late season did not have any feru-
lic acid content. Ocakoğlu et al. (2009) obtained similar results for the cultivars
‘Memecik’ and ‘Ayvalık’.
In the study, the gallic acid content was in the range of 0.06 to 0.30 mg/kg.
The gallic acid content increased with the progress of maturity for ‘Ayvalık’ and
reached to a level approximately three-fold in the optimum harvest period. On the
other hand, it decreased with the progress of maturity for ‘Memecik’. No gallic
acid was determined in ‘Topakaşı’. The highest gallic acid content was recorded in
‘Memecik’ (0.28mg/kg).
Conclusion
It was found that the harvest period and cultivar have significant effect on individual
phenolic components. At the early harvest period-1, ‘Memecik’ and ‘Topakaşı’ had
the highest efficiency in luteolin, cinnamic acid, vanillic acid, and ferulic acid con-
tents, while ‘Ayvalık’ had the highest efficiency in hydroxytyrosol, sinapinic acid,
p-coumaric acid, vanillin and ferulic acid contents. At the optimum harvest period,
‘Ayvalık’ had the highest efficiency in luteolin, tyrosol and gallic acid contents,
while ‘Topakaşı’ had the highest efficiency in tyrosol, hydroxytyrosol and rutin con-
tents. In general, the highest phenolic contents were detected in the early harvest
period-1 (Table3).
On average, the content of tyrosol linearly increased with the progress of harvest
period, whereas the contents of the sinapinic acid, vanillin, vanillic acid and feru-
lic acid decreased. The oils of ‘Memecik’ had significantly higher phenolic content
than those of ‘Ayvalık’ and ‘Topakaşı’ (Table3). In conclusion, the proper harvest
time for oil with high phenolic content was found as the early harvest period-1 for
Table 3 Sum of the phenolic
components content of cvs.
‘Ayvalık’, ‘Memecik’ and
‘Topakaşı’ virgin olive oil (mg/
kg)
Cultivars Harvest period
Early har-
vest time 1
Early har-
vest time 2
Optimum
harvest time
Average
Ayvalık 7.16 7.16 8.10 7.47
Memecik 16.68 13.20 12.95 13.94
Topakaşı 8.98 7.04 7.01 7.68
Average 10.61 9.13 9.35

991
1 3
Biochemical Genetics (2020) 58:981–992
‘Memecik’ and ‘Topakaşı’, which is the beginning of spotting, while it was found as
optimum harvest period for ‘Ayvalık’.
Acknowledgement The study was supported by the Research Project Coordination Unit under the Pro-
ject Number 2601-M-10, at the Suleyman Demirel University.
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Aliations
FatmaYıldırım1 · AdnanNurhanYıldırım1· GülcanÖzkan2· BekirŞan1·
MehmetPolat1· HaticeAşık2· YaşarKarakurt3· SezaiErcişli4
* Fatma Yıldırım
fatmayildirim@isparta.edu.tr
1 Horticultural Sciences Department, Faculty ofAgricultural Sciences andTechnologies, Isparta
University ofApplied Sciences, 32260Isparta, Turkey
2 Food Engineering Department, Faculty ofEngineering, Suleyman Demirel University,
32260Isparta, Turkey
3 Agricultural Biotechnology Department, Faculty ofAgricultural Sciences andTechnologies,
Isparta University ofApplied Sciences, 32260Isparta, Turkey
4 Horticultural Science, Faculty ofAgriculture, Ataturk University, Erzurum, Turkey