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Citation: Alhajj Ali, S.; Mazzeo, A.;
Trani, A.; Pitardi, S.; Bisceglie, S.;
Ferrara, G. An Evaluation of Different
Sweet Olive Cultivars with Different
Ripening Degrees Grown in the
Puglia Region, Southeastern Italy.
Horticulturae 2024,10, 861. https://
doi.org/10.3390/horticulturae
10080861
Academic Editor: Rosario Paolo
Mauro
Received: 11 July 2024
Revised: 9 August 2024
Accepted: 12 August 2024
Published: 14 August 2024
Copyright: © 2024 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
horticulturae
Article
An Evaluation of Different Sweet Olive Cultivars with Different
Ripening Degrees Grown in the Puglia Region,
Southeastern Italy
Salem Alhajj Ali 1, Andrea Mazzeo 1, Antonio Trani 2, Simona Pitardi 1, Sara Bisceglie 1
and Giuseppe Ferrara 1, *
1Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, 70126 Bari, Italy;
salem.alhajj@uniba.it (S.A.A.); andrea.mazzeo@uniba.it (A.M.); simona.pitardi@uniba.it (S.P.);
sara.bisceglie@uniba.it (S.B.)
2
Centre International de Hautes Etudes Agronomiques Méditerranéennes, Mediterranean Agronomic Institute
of Bari, Via Ceglie 9, 70010 Valenzano, Italy; trani@iamb.it
*Correspondence: giuseppe.ferrara@uniba.it; Tel.: +39-080-5442979
Abstract: Some olive cultivars grown in southeastern Italy are characterized by the production of
olives with a reduced level of bitterness. They are known as sweet olive cultivars and fruits are
usually consumed directly or cooked without any debittering process, offering either health benefits
to consumers, thanks to the high content of antioxidants, or an economic benefit to farmers for
their higher price with respect to both table and oil olives. This study evaluates and compares
the organoleptic, pomological, chemical, and physical parameters of seven sweet olive cultivars at
different ripening degrees in the Puglia region over 8 weeks of maturity stage for two consecutive
seasons (2022 and 2023). The organoleptic evaluation was performed by a restricted panel of usual
consumers/experts of sweet olives. The results showed a higher preference for the olive cultivars
locally named Triggiano Dolce, Cerasella, and Mele. Significant differences in weight, length, and
width of the fruits were observed based on both cultivar and year. The phenolic composition of olive
cultivars was significantly affected by both cultivar and harvest year, with Cazzinicchio and Cellina
di Nardòhaving the highest total polyphenols. The analysis of water fraction extracted from olive
samples by liquid chromatography coupled with mass spectrometry led to the identification of eleven
compounds belonging to the secoiroids, phenylpropanoids, phenylethanolids, and flavonoids classes.
The comparison of these compounds among the studied cultivars highlighted significant differences.
Keywords: table olive; Olea europaea L.; marginal areas; Puglia; organoleptic; pomological; chemical
1. Introduction
The olive (Olea europaea L.) is one of the oldest tree species cultivated in the world,
and its products are table olives and virgin olive oil, which have historically represented a
foodstuff of high nutritional value for many populations and countries of the Mediterranean
basin [
1
]. Olive fruits are commonly processed for olive oil extraction, but a small amount of
the 21,449,868 tons of olives produced in 2022 [
2
], around 2.5–3.0 million tons, are consumed
as table olives [
3
]. Table olives are mainly produced in Spain, Turkey, Italy, Portugal, and
Greece, but the market of table olives involves several countries worldwide. Olive and
its processed products have become even more valuable in recent years since their health
benefits have come to light.
Table olives are consumed as appetizers and/or highly healthy culinary ingredients
in many recipes for their low sugar content, high unsaturated fatty acids content, and
additional contribution of fibers, minerals, vitamins, and bioactive components useful to
the diet [1].
Horticulturae 2024,10, 861. https://doi.org/10.3390/horticulturae10080861 https://www.mdpi.com/journal/horticulturae
Horticulturae 2024,10, 861 2 of 13
Taking into account the wide olive germplasm, table olives show sensorial and nutri-
tional characteristics depending on the genotype and the processing method [
4
]. Italy, and
particularly the Puglia region, southeastern Italy, has many olive cultivars that are used for
table olive production, although many of them can be considered dual purpose because
they also produce excellent olive oils.
There are reports of various health benefits of consuming table olives, such as the
prevention of coronary heart, cancer, and inflammation diseases. It has been claimed that
consuming 5–10 table olives per day might cover the daily intake of antioxidants [5].
However, the olive fruit needs to be processed to transform it into an appetizing and
edible food because of its bitterness. There is a wide range of production styles, depending
on the cultivar, ripening degree, and type of fruit (whole or cracked), aimed at hydrolyzing
and/or diffusing into the brine the bitter oleuropein glucoside [
1
]. The most widespread
systems are those that use alkaline hydrolysis or slow acid and enzymatic hydrolysis. In
general, the fermentation step also contributes to the sweetening of the olive fruits, but due
to processing variability, the final table olives produced can vary in color, form, and other
sensorial parameters [6].
Although the chemical constituents of the drupe can vary depending on several factors
(geographical origin, cultivar, cultural practices), the average composition of the drupes
includes 70–76% water, 12–20% oil (mainly oleic acid), 5% total carbohydrates (mainly
dietary fibers), 1.1% proteins, and 4.3% ash (USDA food database). Olives are also an
important source of antioxidants, namely polyphenols, which are classified as follows: phe-
nolic acids, phenolic alcohols, phenylpropanoids, flavonoids, and secoiridoids [
7
,
8
]. Olives,
including table olives, are rich in oleuropein and ligstroside, compounds responsible for
their characteristic bitter taste [
8
]. During the ripening process, hydrolytic activity operated
by endogenous enzymes inside the olive leads to the release of hydroxytyrosol (HT), tyrosol
(Tyr), and elenolic acid, which represent the most abundant phenolic compounds recovered
in table olives, and they are well recognized for their health-promoting characteristics [
9
].
Furthermore, cultivar, environmental (temperature, water availability), and technological
factors, such as the fermentation process, can influence the qualitative and quantitative
phenolic composition of table olives [10].
Among table olives, there are some cultivars defined as ‘sweet olives’ because their
fruits can be eaten fresh without previous debittering treatments. The geographic distri-
bution of such cultivars is limited to some Mediterranean areas with particular climate
and soil characteristics, including the Puglia region in Italy. However, some olive cultivars
grown in the Karaburun peninsula, in the western part of Turkey (locally called Hurma),
are considered sweet olives and mostly come from the Erkence region. These cultivars
go through a natural debittering phase during their ripening period and become ready
to eat as a table olive while still on the tree [
4
]. Similar sweet olives were also reported
in studies from Greece [
11
] and Tunisia [
12
]. Ref. [
13
] found that Hurma olive has a low
phenolic content compared to other cultivars, thus explaining the sweet taste as the effect
of a physiological low content of some compounds responsible for the bitterness. Major
soluble sugars in olives are reported as glucose, fructose, sucrose, xylose, rhamnose, and
mannitol [
14
,
15
]. Sugars not only provide energy for metabolic changes that take place in
the fruit but are also related to the textural properties of the olive. Moreover, sugars are the
precursor for fatty acid biosynthesis and they act as carbon sources for microorganisms
during table olive processing [
14
]. In sweet Thassos olives, for example, glucose and
mannitol were detected as the main sugar and sugar alcohol [
14
]. In naturally debittered
Dhokar olives, glucose and mannitol reach their highest level of concentration at the last
stage of ripening, and their concentrations in naturally debittered Dhokar olives are higher
compared to regular Chemlali olives [
12
]. Organic acids, which are approximately 1.5%
of the flesh part [
16
] of an olive, are produced during the metabolism and catabolism
of the other fruit components, such as carbohydrates [
16
]. According to a study about
Turkish olives, succinic, malic, and citric acids were reported to be the major organic acids
in Memecik and Domat cultivars [
17
]. Citric, succinic, and galacturonic acids were also
Horticulturae 2024,10, 861 3 of 13
identified as the main organic acids in another study which determined the organic acid
profile of olives during the ripening stage [
18
]. Despite these studies, knowledge about the
natural debittering process is limited mostly to phenolic changes, and further studies are
needed to identify the other chemical changes that take place in olive composition during
ripening stages.
In the Puglia region, there are different table olive cultivars, some of them defined as
‘sweet olives’, such as Cerasella, Mele, Pasola, Nolca, Dolce di Cassano, Termite di Bitetto,
etc. These olives are generally consumed after fast and simple processing or cooking. In
the past, cooking methods under ashes were often used, which involved the use of either
braziers or fireplaces to heat houses (with the production of ashes). Other typical recipes of
the Puglia tradition are fried olives with cherry tomatoes and served with the addition of
oil, salt, and, in some cases, pepper; the olives keep their sweet taste with a little appreciated
bitterness. These sweet olives were commonly consumed in the past and often associated
with other minor and neglected fruits such as fig, either fresh or dried [
19
,
20
], during fall
and winter time.
In this study, we compared some table olive cultivars, defined as sweet, cultivated in
the Puglia region for sensory (panel test), qualitative, pomological, and physico-chemical
parameters. The objective of this research was to discriminate the fruits of the considered
cultivars in order to suggest some possible new uses of these olives without any processing
but only for fresh consumption as other fruits.
2. Materials and Methods
2.1. Sample Collection
This study was carried out in the Puglia region, southeastern Italy. The region has
a typical Mediterranean climate with an average temperature of 15–16
◦
C, and it is char-
acterized by warm summers (average temperature 25–30
◦
C) and mild winters (average
temperature 6–10
◦
C), with average annual rainfall ranging between 450 and 650 mm
spread over the seasons, but mostly in autumn–winter, with occasional heavy rains often
occurring in summer in recent years [21].
The investigated cultivars were as follows: Cazzinicchio, Cerasella, Cellina di Nardò,
Mele, Nolca, Termite di Bitetto, and Triggiano Dolce (a local landrace). Samples were
collected during two consecutive seasons (2022 and 2023); in particular, Cerasella, Mele,
and Termite di Bitetto were obtained from the olive repository of the Department of Soil,
Plant and Food Science (Di.S.S.P.A) located in the countryside of Valenzano (Bari province),
Cazzinicchio and Triggiano Dolce form the countryside of Triggiano (Bari province), Cellina
di Nardòfrom the countryside of Lecce, and Nolca from the countryside of Molfetta (Bari
province). Healthy and ripe olives were handpicked at the four cardinal points and
at different heights in the canopy of each tree, placed in paper bags, and successively
transported to the laboratory for analysis. Approximately 1 kg of matured olives (as
commonly harvested in the area for consumption) per tree from three sampled trees per
cultivar was collected each season.
2.2. Sensory Evaluation
Ten volunteer panelists (aged 25–55 years, 6 males and 4 females), chosen for their
usual consumption of sweet olives (hereinafter called the panel), from the Department of
Soil, Plant and Food Science (Di.S.S.P.A) research group (University of Bari ‘Aldo Moro’,
Bari, Italy), were selected to carry out the descriptive sensory analysis of the samples
under study.
To each participant, an aliquot of about 20 olives per sample was presented in a white
plastic dish reporting the sample name. The following attributes were evaluated: flavor
intensity, sweetness, astringency, bitterness, destoning capacity, and overall acceptability.
All these attributes, out of the overall acceptability, were evaluated using an unstruc-
tured graphical scale of 10 points, with the left end representing the lowest intensity of
perception and the right end representing the highest intensity. The overall acceptability
Horticulturae 2024,10, 861 4 of 13
was evaluated using a four-degree structured scale according to the following judgements:
1 = absolutely not; 2 = probably not; 3 = probably yes; 4 = surely yes. Each attribute term
was then described and explained to avoid any doubt about the meaning. The samples
of table olives used for tasting were kept between 20 and 25
◦
C, and the panel test was
performed under diffused daylight. The sensory profile was adapted to the sweet olive
cultivars analyzed in this study from our previous work on the sensory evaluation of fig
products [22].
Destoning capacity is the parameter that evaluates how easily the stone separates from
the flesh inside the oral cavity under the action of incisors and molars and how ’clean‘ from
pulp residues the stone is after expelling it from the mouth [23].
2.3. Pomological, Physical, and Chemical Parameters
The pomological parameters were evaluated for each olive cultivar using weight (g),
length (mm), and width (mm) as evaluation criteria. The average fresh weight of the fruits
was calculated by weighing 100 fresh fruits per replicate, whereas the width and the length
of the olives were measured using a caliper. The olives were destoned, and the stones and
pulp were weighed separately for the determination of the pulp-to-stone (P/S) ratio, an
important trait for table olives.
Successively, for the physio-chemical parameters, the pulp fraction for each sample
was homogenized using a blade blender and transferred in 50 mL centrifuge tubes. After
centrifugation at 6000
×
gper 25 min, a clear water phase was obtained and used for
the following analysis: pH using a pH meter XS Instrument model pH 510, equipped
with pH sensor FoodTrode (Hamilton, Franklin, MA, USA); soluble solids content using
a portable refractometer with automatic temperature control and Brix scaled (model HI
96801, Hanna Instruments, Woonsocket, RI, USA). The water content of the olives was
determined gravimetrically using 30 g of homogenized olive flesh after oven-drying at
105
◦
C until constant weight; the total fat content was obtained using the Soxhlet apparatus,
petroleum ether 40–60
◦
C, and the residue of the water determination. The total polyphenols
content was performed according to [
24
], using 20
µ
L directly from the water phase after
centrifugation and gallic acid as a reference standard for calibration. The results of the total
polyphenols were expressed as a mg of gallic acid equivalent (GAE) per kg of olive pulp.
The ultra-high performance liquid chromatography system consisted of an LPG-
3400 RS quaternary pump, WPS-3000 TRS autosampler, TCC-3000 RS column oven, and
PDA-3000 Dionex, coupled with the HESI-II probe (Thermo Fischer Scientific, Waltham,
MA, USA) and the LTQ Velos Pro ion trap mass spectrometer (Thermo Fischer Scientific,
Waltham, MA, USA). The separation of phenolic compounds was performed on Hipersyl
Gold aQ C
18
1.9
µ
m 2.1
×
100 mm (Waters
TM
, Milford, MA, USA) maintained at 30
◦
C
using a binary mobile phase consisting of (A) water/formic acid (99.9:0.1, v/v) and (B)
methanol/acetonitrile/formic acid (94.9:5:0.1, v/v) at a constant flow rate of 0.3 mL min
−1
.
The gradient program of solvent A was as follows: 0–1 min isocratic 95%; 1–18 min linear
decrease to 55%; 18–20 min linear decrease to 65%. The UV absorbance was monitored at
280 nm. The MS conditions were capillary temperature 320
◦
C; source heater temperature
280
◦
C; nebulizer gas N
2
; sheath gas flow 30 psi; auxiliary gas flow 7 arbitrary units; capil-
lary voltage
−
2800 V, S-Lens RF Level 60%. Data were acquired in negative ionization and
data-dependent methods. The data-dependent settings were full scan from 250 to
1200 m/z,
activation level 65,000 counts, isolation width 2 Da, default charge state 2, and CID energy
35. All data were acquired and processed using Xcalibur v.2 (Thermo Fischer Scientific). A
tentative identification of the phenolic compounds was achieved by a comparison of the
obtained experimental molecular ion [M
−
H]
−
and MS
2
fragmentation patterns with data
reported in the literature. Relative quantities were estimated using the external standard
calibration method and gallic acid, analyzed in the same experimental condition, in a range
of concentration between 0.01 and 10
µ
g/mL. All quantities were expressed as mg/kg of
gallic acid equivalent and used for comparative purposes only.
Horticulturae 2024,10, 861 5 of 13
2.4. Statistical Analyses
All results were analyzed using SPSS v22.0 (IBM). The results of continuous variables,
like soluble solids (
◦
Brix), pH, fat content, olive weight, pulp percentage, and total polyphe-
nols, were compared among cultivars using an ANOVA and Tukey’s post hoc test. The
results obtained by the organoleptic evaluation were processed as nonparametric variables
by applying the Kruskal–Wallis test [25].
3. Results
3.1. Sensory Profiles
Sensory profiles were obtained considering all six parameters (sweetness, astringency,
bitterness, destoning capacity, flavor intensity, and acceptability) assessed by the evaluation
panel. The average values of the organoleptic parameters for the seven cultivars evaluated
are reported in Figure 1.
Horticulturae 2024, 10, 861 5 of 13
range of concentration between 0.01 and 10 µg/mL. All quantities were expressed as
mg/kg of gallic acid equivalent and used for comparative purposes only.
2.4. Statistical Analyses
All results were analyzed using SPSS v22.0 (IBM). The results of continuous varia-
bles, like soluble solids (°Brix), pH, fat content, olive weight, pulp percentage, and total
polyphenols, were compared among cultivars using an ANOVA and Tukey’s post hoc test.
The results obtained by the organoleptic evaluation were processed as nonparametric var-
iables by applying the Kruskal–Wallis test [25].
3. Results
3.1. Sensory Profiles
Sensory profiles were obtained considering all six parameters (sweetness, astrin-
gency, bierness, destoning capacity, flavor intensity, and acceptability) assessed by the
evaluation panel. The average values of the organoleptic parameters for the seven culti-
vars evaluated are reported in Figure 1.
Figure 1. Graphical representation of the organoleptic evaluation results of the olive samples.
In addition, the results of the organoleptic evaluation were reported as numerical
data (statistically analyzed) in Table 1. The data represent the mean of the median values
obtained in the two harvest years (2022 and 2023). The studied cultivars showed some
significant differences between the two seasons.
Considering global appreciation, the cultivars Triggiano Dolce, Cerasella, and Mele,
and, to a lesser extent Nolca, were the table olives preferred by the panelists. Furthermore,
the cultivars Triggiano Dolce and Cerasella were significantly (p ≤ 0.01) the sweetest;
moreover, they had the lowest levels of astringency and bierness, significantly (p ≤ 0.01)
lower compared to the other cultivars. The destoning capacity also showed some signifi-
cant differences among the examined samples, with Triggiano Dolce, Cerasella, and Cel-
lina di Nardò more appreciated when chewing.
When it comes to flavor intensity, Cazzinicchio and Termite di Biteo had signifi-
cantly (p ≤ 0.01) higher values. However, due to their characteristic bierness and astrin-
gency, these cultivars received significantly (p ≤ 0.01) low scores for acceptability, whereas
Triggiano Dolce ranked first also for this parameter (Table 1).
Figure 1. Graphical representation of the organoleptic evaluation results of the olive samples.
In addition, the results of the organoleptic evaluation were reported as numerical
data (statistically analyzed) in Table 1. The data represent the mean of the median values
obtained in the two harvest years (2022 and 2023). The studied cultivars showed some
significant differences between the two seasons.
Table 1. Analysis of variance (ANOVA) and comparison of 2-year means of organoleptic parameters
of the olive samples of the seven olive cultivars 1.
Cultivar SW AS BT DC FI AC
Cellina di Nardò2.0 c 7.4 a 7.1 a 7.5 a 1.6 c 0.9 c
Cerasella 7.3 ab 2.7 c 2.6 c 7.3 a 4.1 b 2.6 a
Cazzinicchio 2.4 c 6.0 a 6.6 a 6.6 b 5.5 a 1.3 c
Termite di Bitetto 4.2 b 5.0 b 5.1 b 6.9 b 5.2 a 2.0 b
Triggiano Dolce 8.0 a 2.5 c 2.8 c 7.7 a 2.6 c 3.1 a
Mele 6.6 b 3.6 c 4.1 b 6.2 c 4.4 b 2.7 a
Nolca 5.5 b 3.4 c 4.3 b 6.6 b 2.6 c 2.5 ab
YEAR - * * - - *
CULTIVAR ** ** ** ** ** **
YEAR ×CULTIVAR - * * - - -
1
Data followed by the same letter are not significantly different, while means with different letters are significantly
different at p
≤
0.05 significant level as determined by Tukey’s test; * p
≤
0.05, ** p
≤
0.01. SW: sweetness; AS:
astringency; BT: bitterness; DC: destoning capacity; FI: flavor intensity; AC: acceptability.
Horticulturae 2024,10, 861 6 of 13
Considering global appreciation, the cultivars Triggiano Dolce, Cerasella, and Mele,
and, to a lesser extent Nolca, were the table olives preferred by the panelists. Furthermore,
the cultivars Triggiano Dolce and Cerasella were significantly (p
≤
0.01) the sweetest;
moreover, they had the lowest levels of astringency and bitterness, significantly (p
≤
0.01)
lower compared to the other cultivars. The destoning capacity also showed some significant
differences among the examined samples, with Triggiano Dolce, Cerasella, and Cellina di
Nardòmore appreciated when chewing.
When it comes to flavor intensity, Cazzinicchio and Termite di Bitetto had significantly
(p
≤
0.01) higher values. However, due to their characteristic bitterness and astringency,
these cultivars received significantly (p
≤
0.01) low scores for acceptability, whereas Trig-
giano Dolce ranked first also for this parameter (Table 1).
3.2. Pomological, Chemical, and Physical Parameters
3.2.1. Pomological Parameters
The morphological parameters of the studied olive cultivars are shown in Figure 2.
The selected set of morphological parameters was adequate to successfully differentiate
each of the drupe and endocarp traits of the seven studied cultivars. Four cultivars, namely,
Cerasuola, Termite di Bitetto, Mele, and Nolca, were characterized by a medium–large olive
size and rounded shape. The remaining Cellina di Nardò, Cazzinicchio, and Triggiano
Dolce had a medium–small size and elongated shape.
The weight, length, and width data for drupes and endocarps show significant dif-
ferences among cultivars and across years (Table 2). From Table 2, the ANOVA results
indicated that the differences in weight (p
≤
0.001), length (p
≤
0.001), and width (p
≤
0.001)
of both drupes and endocarps were significant based on both cultivar and year. The only
exception was the width of endocarp, where the year factor was less significant (p
≤
0.05).
The highest P/S values were noticed for Termite di Bitetto, Cerasella, and Cazzinicchio,
which is a very important aspect when chewing table olives; Triggiano Dolce and Nolca
presented the lowest P/S values.
Horticulturae 2024, 10, 861 6 of 13
Table 1. Analysis of variance (ANOVA) and comparison of 2-year means of organoleptic parameters
of the olive samples of the seven olive cultivars 1.
Cultivar SW AS BT DC FI AC
Cellina di Nardò 2.0 c 7.4 a 7.1 a 7.5 a 1.6 c 0.9 c
Cerasella 7.3 ab 2.7 c 2.6 c 7.3 a 4.1 b 2.6 a
Cazzinicchio 2.4 c 6.0 a 6.6 a 6.6 b 5.5 a 1.3 c
Termite di Biteo 4.2 b 5.0 b 5.1 b 6.9 b 5.2 a 2.0 b
Triggiano Dolce 8.0 a 2.5 c 2.8 c 7.7 a 2.6 c 3.1 a
Mele 6.6 b 3.6 c 4.1 b 6.2 c 4.4 b 2.7 a
Nolca 5.5 b 3.4 c 4.3 b 6.6 b 2.6 c 2.5 ab
YEAR - * * - - *
CULTIVAR ** ** ** ** ** **
YEAR × CULTIVAR - * * - - -
1 Data followed by the same leer are not significantly different, while means with different leers
are significantly different at p ≤ 0.05 significant level as determined by Tukey’s test; * p ≤ 0.05, ** p ≤
0.01. SW: sweetness; AS: astringency; BT: bierness; DC: destoning capacity; FI: flavor intensity; AC:
acceptability.
3.2. Pomological, Chemical, and Physical Parameters
3.2.1. Pomological Parameters
The morphological parameters of the studied olive cultivars are shown in Figure 2.
The selected set of morphological parameters was adequate to successfully differentiate
each of the drupe and endocarp traits of the seven studied cultivars. Four cultivars,
namely, Cerasuola, Termite di Biteo, Mele, and Nolca, were characterized by a medium–
large olive size and rounded shape. The remaining Cellina di Nardò, Cazzinicchio, and
Triggiano Dolce had a medium–small size and elongated shape.
a
d c
b
Termite di Bitetto
Cazzinicchio
Cellina di Nardò Cerasella
Figure 2. Cont.
Horticulturae 2024,10, 861 7 of 13
Horticulturae 2024, 10, 861 7 of 13
Figure 2. Images show the morphological parameters of the different olive cultivars evaluated in
the study. Each square is 2 × 2 cm.
The weight, length, and width data for drupes and endocarps show significant dif-
ferences among cultivars and across years (Table 2). From Table 2, the ANOVA results
indicated that the differences in weight (p ≤ 0.001), length (p ≤ 0.001), and width (p ≤ 0.001)
of both drupes and endocarps were significant based on both cultivar and year. The only
exception was the width of endocarp, where the year factor was less significant (p ≤ 0.05).
The highest P/S values were noticed for Termite di Biteo, Cerasella, and Cazzinicchio,
which is a very important aspect when chewing table olives; Triggiano Dolce and Nolca
presented the lowest P/S values.
The cultivar × year interaction was also significant (p ≤ 0.0001) for all three variables,
suggesting that the considered cultivars have a different response to the drought condi-
tions occurring during summer, which is one of the main factors of variability in the Puglia
region for the agricultural sector.
Table 2. Average values (2022 and 2023) of fresh weight and length and width of drupe and endo-
carp parameters of the seven olive cultivars 1.
Cultivar Drupe Endocarp P/S
Weight
(g)
Length
(mm)
Width
(mm)
Weight
(g)
Length
(mm)
Width
(mm)
Cellina di Nardò 1.55
f
17.44 c 11.57 d 0.29 d 13.63 d 6.06 c 4.15 c
Cerasella 2.74 de 16.76 c 14.92 c 0.37 c 11.80 e 7.65 b 6.38 b
Cazzinicchio 3.43 cd 21.39 b 15.93 bc 0.49 b 16.01 a 7.64 b 6.01 b
Termite di Biteo 5.15 a 23.81 a 18.95 a 0.60 a 15.34 b 8.39 a 7.55 a
Triggiano Dolce 1.23 f 16.95 c 10.44 e 0.23 d 14.12 c 5.61 c 4.34 c
Mele 4.30 b 21.82 b 16.52 b 0.55 ab 15.78 ab 7.70 b 6.80 b
Nolca 2.21 e 12.63 d 12.19 d 0.48 b 12.20 e 8.45 a 3.60 d
YEAR <0.0001 <0.0001 <0.0001 <0.001 <0.0001 <0.05 <0.001
CULTIVAR <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
YEAR × CULTI-
VAR <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
e f
g Nolca
Mele
Tri
gg
iano Dolce
Figure 2. Images show the morphological parameters of the different olive cultivars evaluated in the
study. Each square is 2 ×2 cm.
Table 2. Average values (2022 and 2023) of fresh weight and length and width of drupe and endocarp
parameters of the seven olive cultivars 1.
Cultivar Drupe Endocarp P/S
Weight (g) Length (mm) Width (mm) Weight (g) Length (mm) Width (mm)
Cellina di Nardò1.55 f 17.44 c 11.57 d 0.29 d 13.63 d 6.06 c 4.15 c
Cerasella 2.74 de 16.76 c 14.92 c 0.37 c 11.80 e 7.65 b 6.38 b
Cazzinicchio 3.43 cd 21.39 b 15.93 bc 0.49 b 16.01 a 7.64 b 6.01 b
Termite di Bitetto 5.15 a 23.81 a 18.95 a 0.60 a 15.34 b 8.39 a 7.55 a
Triggiano Dolce 1.23 f 16.95 c 10.44 e 0.23 d 14.12 c 5.61 c 4.34 c
Mele 4.30 b 21.82 b 16.52 b 0.55 ab 15.78 ab 7.70 b 6.80 b
Nolca 2.21 e 12.63 d 12.19 d 0.48 b 12.20 e 8.45 a 3.60 d
YEAR <0.0001 <0.0001 <0.0001 <0.001 <0.0001 <0.05 <0.001
CULTIVAR <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
YEAR ×CULTIVAR <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
1
Data followed by the same letter are not significantly different, while means with different letters are significantly
different at p≤0.05 significant level as determined by Tukey’s test.
The cultivar
×
year interaction was also significant (p
≤
0.0001) for all three variables,
suggesting that the considered cultivars have a different response to the drought conditions
occurring during summer, which is one of the main factors of variability in the Puglia
region for the agricultural sector.
The Termite di Bitetto cultivar had a significantly higher weight, length, and width of
drupes and the weight and width of endocarps. Even if the olive size is strongly affected
by pedoclimatic and agronomic conditions (rainfall, irrigation, fertilization, and pruning),
Termite di Bitetto resulted in being the cultivar characterized by bigger fruit parameters
even if the fruits’ average sizes were lower in 2023 with respect to the values observed in
Horticulturae 2024,10, 861 8 of 13
2022. Similarly, the Triggiano Dolce cultivar was characterized by the smallest fruit size,
followed by the Cellina di Nardò(Table 2).
3.2.2. Chemical and Physical Parameters
The mean values of the chemical and physical parameters are reported in Table 3.
Significant differences among cultivars were observed for all considered parameters. The
harvest year showed significant effects on pulp, water, fat percentage, and polyphenols.
The cultivar
×
year interaction was significant only for the fat content, showing important
changes in the same cultivars probably because of the different climatic conditions that
strongly affected the ripening process and oil accumulation (drought, high temperatures,
etc.). Among the studied olive cultivars, Cazzinicchio had the highest content of polyphe-
nols, followed by Cellina di Nardò, both with a value of about 300 mg/kg. In contrast, the
lowest polyphenol values were detected in the cultivars Cerasella, Mele, and Triggiano
Dolce, the ones which also showed the highest sweetness. The pH values showed no
significant differences, and in both years, Nolca and Triggiano Dolce were characterized
by the lowest pH values. In the same manner of pH, soluble solids (
◦
Brix) resulted in
no significant difference in the two seasons, but Nolca and Triggiano Dolce reported the
highest values among the studied cultivars.
Table 3. Average values (2022 and 2023) of chemical and physical parameters of the olive samples of
the seven olive cultivars 1.
Cultivar Pulp
(%) pH Soluble
Solids (%)
Water
(%)
Fat
(%)
Polyphenols
(mg/kg)
Cellina di Nardò74.3 c 5.1 a 9.5 cd 41.1 a 18.1 b 287 ab
Cerasella 80.7 b 5.1 a 8.0 d 35.2 c 15.0 c 158 c
Cazzinicchio 75.1 c 5.1 a 10.0 c 35.8 c 14.7 c 334 a
Termite di Bitetto 82.6 a 5.1 a 10.3 c 37.2 bc 18.8 b 245 b
Triggiano Dolce 59.9 d 4.8 b 11.0 b 21.0 d 7.2 d 175 c
Mele 80.5 b 5.2 a 8.5 d 41.5 a 24.5 a 179 c
Nolca 78.6 b 4.9 b 13.8 a 41.4 a 11.9 c 270 b
YEAR <0.01 <0.01 <0.01 <0.01
CULTIVAR <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
YEAR ×CULTIVAR <0.01
1
Data followed by the same letter are not significantly different while means with different letters are significantly
different at p≤0.05 significant level as determined by Tukey’s test.
The identification data obtained by LC/MS are reported in Table 4. Eleven phenolic
compounds were identified in the water phase of the olive samples. In two cases, at
retention times of 9.78 and 13.42, there was a coelution of two compounds in the same UV
peak at 280 nm and they were quantified together in the successive Table 5. Six out of the
eleven identified compounds belong to the class of secoiridoid, rutin and luteolin rutinoside
belong to the class of flavonoid, p-coumaroyl-hexoside and verbascoside belong to the class
of phenylpropanoid, and hydroxytyrosol belongs to the class of phenylethanoid.
The quantitative data related to the identified compounds are reported in Table 5.
There were important differences among the analyzed samples. Cerasella showed only
trace amounts (not quantified) for almost all target compounds, with the exception of
1-D-glucopyranosyl acyclodihydroelenolic acid. The cultivars with the highest number of
detected compounds were Cellina di Nardò, Cazzinicchio, and Triggiano Dolce with seven
compounds detected in a quantifiable amount.
Horticulturae 2024,10, 861 9 of 13
Table 4. Identification data of compounds found in the water phase of olive samples.
MH−=
Negative
molecular ions m/z, MS
2
= Second stage fragmentation pattern. The number in brackets represents the
relative intensity.
RT MH−MS2ID Ref.
2.12 407 389 (100)-357 (30)-375 (30) 1-D-glucopyranosyl acyclodihydro
elenolic acid [24]
3.78 315 153 (100) OH-tyrosol glucoside [26,27]
7.16 325 163 (100)-119 (10) p-Coumaroyl-hexoside [28]
7.51 421 403 (100)-359 (40)-389 (15) Oleoside methylester derivative [29]
9.78 593 285 (100) Luteolin rutinoside [26,28,30]
377 197 (100)-153 (15) Oleuropein aglycone derivative [26,27]
11.38 525 195 (100)-481 (70)-389 (60)-319 (60) Demethyloleuropein [27]
12.15 623 461(100) Verbascoside [26]
13.42 609 301 Rutin [26]
319 195 (100)-301 (20)-165 (20) 3,4-DHPEA-EDA [30]
Table 5. Quantitative data were obtained by LC/MS of polyphenol compounds identified in the
water phase of the olive samples. Values are in mg/kg gallic acid equivalent 1.
RT Cellina di NardòCerasella
Cazzinicchio
Termite di Bitetto
Dolce Triggiano
Mele Nolca
2.12 127.9 a 9.1 c 27.8 b 38.2 b 9.3 c 38.6 b 22.0 b
3.78 – – 22.6 b 18.7 b 10.3 b 24.5 b 91.4 a
7.16 17.8 – 5.5 – – – –
7.51 – – 3.6 – 4.8 5.7 13.4
9.78 92.8 – – – 33.9 – –
11.38 – – – – 3.5 11.0 7.4
12.15 14.0 b – 23.8 b 4.4 c 20.2 b 34.1 b 135.0 a
13.42 60.4 ab – 81.9 a 4.9 c 57.2 b 67.7
ab 24.5 bc
15.93 16.2 – 13.2 6.8 – 14.3 –
Tot. mg/kg 329.1 a 9.1 c 178.5 b 73.0 b 139.2 b 195.9
b293.7 a
1
Within each row, means with different letters are significantly different according to Tukey’s test at p< 0.001. See
Table 4for the identification data and considering the retention time.
4. Discussion
In the literature, the topics regarding the importance of pomological and sensory
properties in food quality evaluations [
31
,
32
] have been extensively discussed. On the other
hand, few studies are available relating to the chemical, pomological, and sensory analysis
of the so-called sweet table olives.
In the present study, we provided valuable insights into important characteristics of
different sweet olive cultivars in the Puglia region and ways that these cultivars could
receive more attention for their economic and health values.
Despite its importance as a commercial parameter, both the determination of the
pulp-to-stone ratio (P/S) and the percentage of pulp contributed to the comprehensive
chemical analysis of the olive samples. A recent paper [
33
] indicated, for maintaining the
commercial value of table olives, that the size and pulp-to-stone ratio are very important
parameters in the table olive market. In this study, the Termite di Bitetto cultivar has a
pulp of 82.6%, which was significantly higher compared to other cultivars. With a high
pulp-to-stone ratio (7.55), Termite di Bitetto can be considered a cultivar with a noteworthy
commercial value. Ref. [
34
] indicated that the commercial value increases with the increase
in the pulp-to-stone ratio.
Size does matter, but there are also other important factors attracting consumers to the
table olive market. From the organoleptic evaluation’s point of view, the sensory profiles of
the seven olive cultivars indicated that olive sweetness appeared to be the most influencing
Horticulturae 2024,10, 861 10 of 13
factor in the panel’s overall acceptability. This is the case of the cultivars Cerasella, Triggiano
Dolce, and Mele. Theoretically, the sweet taste should be correlated with the soluble solids
content. The sweetness was more appreciated by younger panelists with respect to the
more expert (older) ones who appreciated the bitterness of some olive cultivars. However,
this difference in the organoleptic characteristics of the examined cultivars could be used to
target each cultivar to different consumers, i.e., consumers appreciating more the sweet
vs. consumers appreciating the bitter. However, in partial disagreement with our results,
ref. [
35
] found that olive flavor is the influencing factor due to qualitative and quantitative
compositions of volatiles, and the fragrance transmitted derivates from an equilibrium of
several chemical classes of volatile compounds. In our study, the cultivars Cazzinicchio
and Termite di Bitetto had higher flavor scores; however, the lowest acceptability scores
recorded (1.3 and 2, respectively, out of 4) suggested that, for market orientation, more
organoleptic parameters of table olives should be considered instead of flavor. Maybe
consumers first buy with their eyes and nose, but they continued to keep buying with their
mouth. Moreover, the Cellina di Nardòsamples showed significantly lower values for
most of the organoleptic parameters considered. This can be understood, given the small
size of the olives, as the green-to-black ripening stage and the transformation process [
7
].
It should be kept in mind that this cultivar is mainly used for olive oil production and in
baking (puccia salentina, a bread cooked with Cellina di Nardòolives).
Similarly to other fruits, sweet table olives could be consumed fresh as appetizers or
cooked as side dishes for main courses of meat and fish. Cultivars with a general lower
bitterness should be preferred for fresh consumption, whereas for cooked dishes, either
sweet or bitter cultivars could be used.
In Table 6, the results of the rPearson correlation coefficients are reported. The results
have a chromatic scale, with green indicating a positive correlation and red a negative one.
As expected, and well known by the scientific literature, there is a negative correlation
between the pH of fruit and soluble solids due to the progressive reduction in organic
acid and accumulation of sugars during ripening. In the results of the present work, the
bitterness and astringency of the olive are strongly positively correlated (r> 0.7), and both
are positively correlated with the total polyphenols content. On the other hand, the total
polyphenols content is strongly and negatively correlated with sweetness.
Table 6. Pearson correlation among the organoleptic descriptors and chemical parameters.
pH Soluble Solids
Polyphenols
Sweetness
Astringency
Bitterness
pH 1
Soluble
solids −0.8 1
Polyphenols
−0.2 0.4 1
Sweetness
−0.1 0.0 −0.9 1
Astringency
0.2 −0.1 0.8 −1.0 1
Bitterness 0.1 0.0 0.9 −1.0 1.0 1
The Pearson correlation analysis was also performed on the results of the LC/MS data
and the organoleptic parameters, with the results reported in Table 7. Almost all target
compounds have a negative correlation with the sweetness sensation. Two compounds, at
retention times of 7.16 and 9.78, have a strong positive correlation with both astringency and
bitterness. The chromatographic peak at 7.16 was identified as a glucoside of p-coumaric
acid, whereas at a retention time of 9.78, there were two identified compounds, namely
luteolin rutinoside and oleuropein aglycon. Bitterness and astringency were also positively
correlated with the concentration of the oleanolic acid derivate (RT 2.12) and the oleuropein
derivate (RT 11.39). It is worth mentioning that there was a weak negative correlation
between the verbascoside content and both astringency and bitterness. The sweet olive
cultivars with a sweet taste were characterized by a lower content of polyphenols such as
luteolin rutinoside and oleuropein aglycon.
Horticulturae 2024,10, 861 11 of 13
Table 7. Pearson correlation analysis among the compound identified by LC/MS and the organoleptic
evaluation.
RT Sweetness Astringency Bitterness
2.12 −0.7 0.8 0.7
3.79 −0.1 −0.2 0.0
7.16 −1.0 1.0 1.0
7.52 0.1 −0.3 −0.2
9.78 −1.0 1.0 1.0
11.39 −0.6 0.9 0.8
12.16 0.,2 −0.4 −0.3
13.39 −0.1 0.2 0.2
15.94 −0.2 0.3 0.4
Tot. mg/kg −0.5 0.5 0.6
5. Conclusions
This work is the first report on the identification and characterization of important
organoleptic, pomological, qualitative, and physico-chemical parameters of seven sweet
olive cultivars in the Puglia region (southeastern Italy).
Termite di Bitetto and Cerasella resulted in being the cultivars characterized by bigger
fruit dimensions and, with Mele, a high pulp-to-stone ratio.
The highest value of total polyphenols was observed in the Cazzinicchio and Cel-
lina di Nardòsamples with a value close to 300 mg/kg. Triggiano Dolce and Cerasella
were characterized by the sweetness in the panel evaluation and good acceptability, thus
suggesting a better use for fresh consumption.
The polyphenols detected in some olive cultivars partly explained the more astringent
and bitter taste of such cultivars.
In comparison with the existing literature, this work provides new information about
the sensory, physico-chemical, and pomological data already available about sweet olive
cultivars. However, there has been limited research conducted on table olives (and even less
for sweet olives), and there is still not a real focus on the sweet olive market possibilities.
In conclusion, despite their economic value, as they could be eaten fresh without
previous debittering treatment or cooked for many dishes, this study revealed important
information regarding the chemical compositions of different sweet olive cultivars. Further
studies on the effects of environmental factors and growing conditions on the studied
parameters are required to promote ‘sweet olives’ for wider fresh consumption.
Author Contributions: Conceptualization, G.F., A.M. and A.T.; methodology, G.F., A.M. and A.T.;
formal analysis, A.M. and A.T.; investigation, A.T., A.M. and G.F.; data curation, A.T., S.A.A., S.P. and
S.B.; writing—original draft preparation, A.T., S.A.A., S.P., S.B. and G.F.; writing—review and editing,
S.A.A., A.T., A.M. and G.F.; supervision, G.F. All authors have read and agreed to the published
version of the manuscript.
Funding: This study was partly carried out within the Agritech National Research Center and re-
ceived funding from the European Union Next-Generation EU (PIANO NAZIONALE DI RIPRESA E
RESILIENZA (PNRR)—MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4—D.D. 1032 17/06/2022,
CN00000022). This activity was also conducted within the DAJS (Distretto Agroalimentare di qualità
Jonico Salentino) (CUP: J89J21013750001).
Data Availability Statement: The raw data supporting the conclusions of this article will be made
available by the authors on request.
Acknowledgments: The authors wish to thank the people participating in the panel test, in particular
Giuseppe Gambacorta.
Conflicts of Interest: The authors declare no conflicts of interest.
Horticulturae 2024,10, 861 12 of 13
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