Content uploaded by Francesco Sottile
Author content
All content in this area was uploaded by Francesco Sottile
Content may be subject to copyright.
Antioxidant Compounds and Qualitative Traits in European (Prunus
domestica L.) and Japanese (P. triflora L.) Plum Fruits as Affected by
Cold Storage
F. Sottile and F.M. Impallari
Dipartimento di Colture Arboree
University of Palermo
Viale delle Scienze 11
90110 Palermo (PA)
Italy
C. Peano
Dipartimento di Colture Arboree
University of Torino
Via Leonardo da Vinci 44
10195 Grugliasco (TO)
Italy
N.R. Giuggioli
Dipartimento di Scienza dei materiali ed ingegneria chimica
Politecnico di Torino
C.so Duca degli Abruzzi 24
10129 (TO)
Italy
Keywords: germplasm, ‘Ariddo di core’, ‘Sanacore’, ‘Ramassin’, characterization,
nutraceutical, Tectrol®
Abstract
The Italian territory is rich in fruit trees germplasm and in the last years
many research programs have been carried out to characterize local cultivars and
accessions for deepenings about them and enhancing the market agreement too. The
Sicilian plum cultivars ‘Sanacore’ and ‘Ariddo di core’ and the Piedmontese plum
cultivar ‘Ramassin’ were studied to highlight their qualitative traits including the
nutraceutical properties. Moreover, since it is important to know in which way the
qualitative parameters change during the storage period one more study was carried
out by storing the fruits under modified atmosphere in the Tectrol® system. The
results evidenced very interesting aspects about the qualitative characteristics of the
cultivars studied and a positive influence of the modified atmosphere during storage.
INTRODUCTION
In the last years, the increasing interest for local cultivars of several fruit species
led many researches aimed to characterize these cultivars and to identify interesting
qualitative traits. The Italian territory is particularly rich in local accessions of many fruit
tree species such as pome fruits, stonefruits and other less cultivated species; in this way,
many projects were recently funded to better know and evaluate that local fruit species
biodiversity. Among the stonefruits, the plum germplasm is very rich in Italy and it has a
very ancient origin as many historical proofs showed. In fact, the most ancient
archeological proofs of the presence of wild plums in the Italian territory date from the
fourth millennium and other information about the plum cultivation are in the first
millennium in the Greek and Roman literature (Zohary and Hopf, 1993). Inside that
germplasm some accessions are still cultivated and have been recognized to have good
characteristics by the local markets. The present study has been aimed to determine the
qualitative characteristics of three Italian plum cultivars, the Sicilian plums ‘Ariddo di
core’ and ‘Sanacore’ and the Piedmontese plum ‘Ramassin’. The value of these cultivars
with an important place in the local markets is being more recognized through the
introduction in the niche national and international markets. So, a better knowledge about
their qualitative traits has been considered helpful in order to increase and enhance their
diffusion in the market.
Besides classical fruit qualitative parameters such as colour, firmness, size, soluble
solids content, titratable acidity, flavour, recently much relevance was given to other
important qualitative traits such as those that concern the nutraceutical properties. Several
1145
Proc. 6th International Postharvest Symposium
Eds.: M. Erkan and U. Aksoy
Acta Hort. 877, ISHS 2010
studies showed that the nutraceutical compounds are important molecules with helpful
actions for the human health mainly in relation to their antioxidant activity; also a lower
incidence of cardiovascular diseases and cancer has been proven in people eating a high
quantity of fruits and vegetables, particularly those with high antioxidant compound
amounts (Albasini, 1991; Block et al., 1991; Okuda, 1997; Scalzo et al., 2005). In fruits
and vegetables the antioxidant compounds content, as well as other qualitative traits, are
influenced by several factors besides the genotype and differences in the fruit quality can
be evident upon several causes. Among them the post-harvest management, particularly
the storage conditions, have been proven to be very important for the evolution of many
qualitative and nutraceutical characteristics. In fact, under adequate storage conditions,
the fruits maintain good firmness, colour and flavour as according to the consumer’s
demands and expectations. So, together with a qualitative characterization of the three
Italian plum cultivars ‘Ariddo di core’, ‘Sanacore’ and ‘Ramassin’ aimed to highlight
their main traits, it appeared interesting also to investigate in which way some specific
qualitative characteristics would change after a storage period under modified atmosphere
using a Tectrol® system.
MATERIALS AND METHODS
The Sicilian plum cultivars ‘Sanacore’ and ‘Ariddo di core’ and the Piedmontese
plum cultivar ‘Ramassin’ were studied to highlight their qualitative traits compared with
‘Angeleno’ and ‘TC Sun’, appreciated on the global market and used in this work as
references.
The qualitative parameters observed were: fruit weight, used to classify the fruit
size, firmness, soluble solids content and titratable acidity. The data collected have been
statistically processed by a cluster analysis to point out their similarity.
On the Sicilian cultivars ‘Ariddo di core’ and ‘Sanacore’ the nutraceutical aspects
were deepened in comparison to ‘Angeleno’. For the determination of the total
polyphenolics and anthocyanins content and of the antioxidant activity, an extract from a
sample of each cultivar was obtained using 10 g of flesh and skin after 1 hour in dark
conditions in 25 ml of a 100% methanol, distilled water and 37% hydrochloridric acid
mixture, then homogenized and centrifuged at 3000 gpm for 20 minutes. Total
polyphenolics content was determined through the Slinkard and Singleton (1977) method
using the Folin-Ciocalteau reagent. After 2 hours at room temperature, the absorbances
were measured at 765 nm with a Varian Cary 50 UV-Visible spectrophotometer using
1 cm path length quartz cells. Results were expressed as mg gallic acid equivalent (GAE)
per 100 g of fresh weight (FW). Total anthocyanins content was determined using the pH
differential method and diluting the samples in two buffer solutions at pH 1.0 and 4,5.
After 20 minutes at room temperature the sample absorbances were measured at 515 and
700 nm (Cheng and Breen, 1991; Giusti and Wrolstad, 2001). The pigment content was
expressed as cyaniding-3-glucoside (Cyd-3-glu) per 100 g FW considering an extinction
coefficient of 26900 L cm-1 mol-1 and a molecular weight of 449.2 g mol-1. The
investigation on the antioxidant activity was carried out through the Ferric reducing
antioxidant power (FRAP) test following the Benzie and Strain (1996) protocol and using
a tripiridiltriazine - Fe3+ complex and a reaction pH 3,6. The sample absorbances were
measured at 595 nm after 30 minutes at 37°C and the antioxidant power value was
expressed as mmol Fe2+ per 100 g FW.
On ‘Sanacore’ and ‘Ramassin’ the volatile compounds were determined through
their extraction by a Purge and Trap technique (Ebeler et al., 2001) using helium ultra-
pure at 75°C. The different compounds were separated using the gaschromatograph -
mass spectrometer (GC/MS) Shimadzu QP5000 with a column Supelco MDN 5S (60 m
0.25 id, 0.25 µm film).
In order to evidence changes in qualitative traits during a storage period,
‘Ramassin’ and ‘Sanacore’ fruits were stored in 500 g pots disposed in pallets in modified
atmosphere (MA) obtained with a Tectrol® system using values of 12% O2 and 12% CO2.
Daily monitoring was appropriately managed for gas concentrations and the modification
1146
of the atmosphere. Before setting up the experimental pallets, analyses on the qualitative
parameters (firmness, soluble solids content and titratable acidity) were carried out and
each container was weighed. After 30 days of storage the fruits were analyzed to detect
changes in the firmness, soluble solids content and titratable acidity and the weight of
each container was recorded again. Also, to investigate the influence of different storage
methods on the fruit weight changes, three containers for each cultivar were stored in a
refrigerated room in non-modified atmosphere (nMA) and weighed at the beginning and
at the end of the storage period.
All data collected were statistically processed using Systat 10 to determine means,
standard deviation and percentage coefficient of variation. Also the variance analysis was
performed through Tukey test.
RESULTS
The biometric and qualitative characterization has evidenced some common traits
in the studied germplasm cultivars. In fact, they are associated by the fruit size, that is
very small, and by high soluble solids content, that can be assimilated to those of the
international cultivars ‘Angeleno’ and ‘TC Sun’. The titratable acidity is low in
‘Ramassin’ (3,8 g/L) and higher in ‘Sanacore’ and ‘Ariddo di core’, in any case lower
than 7 g/L. Firmness is usually low, showing a very soft flesh in ‘Sanacore’ and
‘Ramassin’ and a medium in ‘Ariddo di core’ (Table 1). The cluster analysis carried out
on these data shows high similarity among the three germplasm cultivars, as evidenced in
the dendrogram by same colour lines, and more distance from the international cultivars
‘Angeleno’ and ‘TC-Sun’ (Fig. 1).
The study about the nutraceutical properties carried out on the Sicilian plums
‘Sanacore’ and ‘Ariddo di core’ has showed very interesting characteristics of these
cultivars which showed a high total polyphenolics content. In particular, the cultivar
‘Ariddo di core’ shows a polyphenolics content higher than ‘Angeleno’ and the highest
value of antioxidant activity among the cultivars studied. On the contrary, the
anthocyanins content of the Sicilian cultivars is lower than ‘Angeleno’ (Table 2) but
considerably acceptable if compared with the bibliographic values (Vangdal and
Slimestad, 2006).
About the volatile compounds of ‘Ramassin’ and ‘Sanacore’, the GC/MS
technique allowed to determine the presence of many molecules on the chromatograms
(Figs. 2 and 3) and, among them, the most representative have been identified. Moreover,
the quantitative variation of these compounds after a storage period in MA evidenced a
high decrease of almost every compound both in ‘Ramassin’ and ‘Sanacore’ (Fig. 4).
Data on storage tests in MA on ‘Sanacore’ and ‘Ramassin’ are shown in Tables 3
and 4. After 30 days of storage in MA ‘Sanacore’ showed a slight decrease of soluble
solids content while a stronger reduction of the titratable acidity that leads to an increased
SSC/TA (soluble solids content/titratable acidity) value and to enhanced qualitative
characteristics. In ‘Ramassin’ the titratable acidity had a lower decrease ratio than the
soluble solids content so that a decrease of the SSC/TA value was evidenced, although
negligible. ‘Ramassin’ showed a very low fruit weight-loss: firmness decreases by 6%
whereas in ‘Sanacore’ by 38%. In MA storage a smaller decrease was evident both in
‘Ramassin’ and ‘Sanacore’ (Table 5 and 6). In fact in MA compared with nMA storage,
the weight decrease shows a reduction of 65 and 86% in ‘Sanacore’ and ‘Ramassin’
respectively; the average daily weight loss in ‘Sanacore’ is 1 g in nMA and 0,32 g in MA
whereas in ‘Ramassin’ it is 2,50 g in nMA and 0,31 g in MA. So in nMA storage,
‘Ramassin’ shows the highest daily weight decrease whereas in MA a slightly higher
weight decrease is in ‘Sanacore’ that loses 3% weight more than ‘Ramassin’.
DISCUSSION
The results highlighted many interesting aspects about the qualitative
characteristics of the germplasm plum cultivars studied and their maintenance during
storage in MA.
1147
It was shown that the cultivars ‘Ramassin’, ‘Sanacore’ and ‘Ariddo di core’ are
characterized by very small fruits, a generally typical trait of the plum germplasm, and by
good qualitative characteristics that can be interesting for an agreement by the global
market. Certainly, the low firmness values can represent a problem for the fruit storage
and their post-harvest management even if in MA a very low decrease has been
evidenced; also, it needs to be considered that this parameter is strongly affected by the
harvest time so it can be enhanced by a better defining of the harvest index in the field.
The similarity of the qualitative traits among the Sicilian and the Piedmontese
cultivars evidenced by the cluster analysis confirms that the germplasm is a genetic pool
merged by similar qualitative traits although selected in different areas with specific
environmental pressure. Moreover, the appreciable nutraceutical properties of the
Sicilians plum cultivars studied can represent one more value to enhance their
consumption with an important reactions on the recovery and exploitation actions of the
germplasm cultivars.
Also the different storage techniques showed a positive influence of the MA on
the qualitative traits with a decrease of the weight-losses. That is very interesting since it
proves that using appropriate storage conditions it is possible to maintain the fruit
qualitative characteristics. Surely more studies need to deepen some aspects, overall about
the effects of the MA considering that for the test in the Tectrol® system a long storage
period was adopted.
ACKNOWLEDGEMENTS
This research is part of a national project “Improved technological methods for
post-harvest management of high quality fruits”. Special thanks to the Floramo
corporation srl for their work.
Literature Cited
Albasini, A. 1991. Principi attivi dei piccoli frutti: realtà e nuove acquisizioni.
Erboristeria Domani, Novembre.
Benzie, I.F.F. and Strain, J.J. 1996. The ferric reducing ability of plasma (FRAP) as a
measure of ‘antioxidant power’: The FRAP assay. Analytical Biochemistry 239(1):70-
76.
Block, G., Patterson, B. and Subar, A. 1991. Fruit, vegetables, and cancer prevention: a
review of the epidemiological evidence. Nutr. Cancer 18(1):1-29.
Cheng, G.W. and Breen, P.J. 1991. Activity of phenylalanine ammonia-lyase (PAL) and
concentrations of anthocyanins and phenolics in developing strawberry fruit. Journal
American Society of Horticultural Science 116:865-869.
Ebeler, S.E., Sun, G.M., Datta, M., Stremple, P. and Vickers, A.K. 2001. Solid-phase
microextraction for the enantiomeric analysis of flavors in beverages. Journal of
AOAC International 4(2).
Giusti, M.M. and Wrolstad, R.E. 2001. Characterization and measurement with UV-
visible spectroscopy. Current Protocols in food analytical chemistry: F1.2.1.-F1.2.13.
R.E. Wrolstad (ed.), John Wiley and Sons: New York.
Okuda, T. 1997. Phenolics antioxidants. Food and free radicals: 31-48. New York, NY:
Plenum Press.
Scalzo, J., Politi, A., Pellegrini, N., Mezzetti, B. and Battino, M., 2005. Plant genotype
affects total antioxidant capacity and phenolic contents in fruit. Nutrition 21:207-213.
Slinkard, K. and Singleton, V.L. 1977. Total phenol analysis, automation and comparison,
with manual methods. American Journal of Enology and Viticulture 28:49-55.
Vangdal, E. and Slimestad, R. 2006. Methods to determine antioxidative capacity in fruit.
Journal of Fruit and Ornamental Plant Research 14(2):123-131.
Zohary, D. and Hopf, M. 1993. Domestication of plants in the old world. Clarendon
Press, Oxford.
1148
Tables
Table 1. Qualitative characteristics of the Italian plum germplasm cultivars ‘Ariddo di
core’, ‘Ramassin’ and ‘Sanacore’ compared with ‘Angeleno’ and ‘TC Sun’.
Fruit weigth
(g) Firmness
(kg/cm2)
Soluble
solids content
(°Brix)
Titratable acidity
(g/L) SSC/TA
Sanacore 19,26 ± 5,0 0,66 ± 0,4 14,88 ± 1,1 6,86 ± 2,4 2,10± 1,0
Ariddo di core 16,75 ± 3,0 1,30 ± 0,4 20,10 ± 2,0 6,13 ± 0,8 3,27± 0,6
Ramassin 9,10 ± 1,5 0,69 ± 0,1 17,24 ± 3,0 3,80 ± 1,0 4,53± 0,8
Angeleno 86,23 ± 2,4 1,30 ± 0,1 17,00 ± 0,1 1,20± 0,1 14,17± 0,1
TC Sun 54,43± 14,6 1,30 ± 0,1 22,00 ± 0,1 1,20 ± 0,1 18,33± 0,1
Table 2. Nutraceutical properties of the Sicilian cultivars ‘Ariddo di core’ and ‘Sanacore’
compared with cultivar ‘Angeleno’.
Total polyphenolics
(mg GA/100 g FW) Total anthocyanins
(mg Cyd-3-Glu/100 g FW) FRAP
(mmol Fe2+/100 g FW)
Sanacore 141,01 ± 14,9 4,84 ± 0,7 918 ± 0,3
Ariddo di core 391,56 ± 21,3 1,22 ± 0,7 39,03 ± 0,9
Angeleno 240,01 ± 46,4 53,20 ± 24,0 486 ± 0,2
Table 3. Changes in the qualitative parameters of the Sicilian plum cultivar ‘Sanacore’
after 30 days of storage in modified atmosphere (MA).
Firmness
(kg/cm2) Soluble solids content
(°Brix) Titratable acidity
(g/L) SSC/TA
Start 0,66 a 14,88 a 6,86 a 2,17 a
After 30 dd in MA 0,41 b 13,71 b 3,98 b 3,44 b
In the same column, values marked with different letters are significantly different at P<0.05.
Table 4. Changes in the qualitative parameters of the Piedmontese plum cultivar
‘Ramassin’ after 30 days of storage in modified atmosphere (MA).
Firmness
(kg/cm2) Soluble solids content
(°Brix) Titratable acidity
(g/L) SSC/TA
Start 0,69 n.s. 17,25 a 3,80 n.s. 4,53 n.s.
After 30 dd in MA 0,65 14,75 b 3,42 4,31
In the same column, values marked with different letters are significantly different at P<0.05.
1149
Table 5. Changes in the fruit weight of the Sicilian plum cultivar ‘Sanacore’ after 30 days
of storage in modified atmosphere (MA) compared with non-modified atmosphere
(nMA).
Total weight loss after 30 dd
(g) Average daily loss
(g/day)
nMA 29,00 a 1,00 a
MA 10,17 b 0,32 b
In the same column, values marked with different letters are significantly different at P<0.05.
Table 6. Changes in the fruit weight of the Piedmontese plum cultivar ‘Ramassin’ after 30
days of storage in modified atmosphere (MA) compared with non-modified
atmosphere (nMA).
Total weight loss after 30 dd
(g) Average daily loss
(g/day)
nMA 72,00 a 2,50 a
MA 9,90 b 0,31 b
in the same column, values marked with different letters are significantly different at P<0.05.
Figures
0.0 0.5 1.0 1.5 2.0
Distances
SANACORE
A
RIDDO DI CORE
RAMASSIN
ANGELENO
TC SUN
0.0 0.5 1.0 1.5 2.0
Distances
SANACORE
A
RIDDO DI CORE
RAMASSIN
ANGELENO
TC SUN
0.0 0.5 1.0 1.5 2.0
Distances
SANACORE
A
RIDDO DI CORE
RAMASSIN
ANGELENO
TC SUN
0.0 0.5 1.0 1.5 2.0
Distances
SANACORE
A
RIDDO DI CORE
RAMASSIN
ANGELENO
TC SUN
Fig. 1. Cluster dendrogram of similarity for the qualitative characteristics of the Italian
plum germplasm cultivars ‘Ramassin’, ‘Ariddo di core’ and ‘Sanacore’ compared
with the international cultivars ‘Angeleno’ and ‘TC Sun’.
1150
Most representative peaks: 1. Ethyl isopropoxy acetate; 5. 1-Butanol;
14. Butanoc acid ethyl ester; 15. n-hexyl acetate; 36. Hexanoic acid
ethyl ester; 37. Cis-3-exenylacetate; 38. 1-Hexyl acetate; 58 Hexyl
butanoate; 59. Ethyl octanoate; 71. Ethyl cis-4 decenoate; 72. Hexyl
exoate.
Fig. 2. Chromatogram of volatile compounds of the Piedmontese cultivar ‘Ramassin’.
Most representative peaks: 2. 3-Methyl butanal; 3. 1-Butanol; 10.
Butanoc acid butyl ester; 33. Isobutyl- isobutyrrate; 34. Hexanoic acid
ethyl ester; 59. Hexyl butanoate; 60. Ethyl octanoate; 64. Hexyl 2
methylbutanoate; 70. Ethyl cis-4 decenoate; 71. Hexyl exoate.
Fig. 3. Chromatogram of volatile compounds of the Sicilian cultivar ‘Sanacore’.
1151
Peaks ‘Ramassin’: 1. Ethyl isopropoxy acetate; 5. 1-Butanol; 14. Butanoc acid
ethyl ester; 15. n-hexyl acetate; 36. Hexanoic acid ethyl ester; 37. Cis-3-
exenylacetate; 38. 1Hexyl acetate; 58 Hexyl butanoate; 59. Ethyl octanoate; 71.
Ethyl cis-4 decenoate; 72. Hexyl exoate.
Peaks ‘Sanacore: 2. 3-Methyl butanal; 3. 1-Butanol; 10. Butanoc acid butyl
ester; 33. Isobutyl- isobutyrrate; 34. Hexanoic acid ethyl ester; 59. Hexyl
butanoate; 60. Ethyl octanoate; 64. Hexyl 2 methylbutanoate; 70. Ethyl cis-4
decenoate; 71. Hexyl exoate.
Fig. 4. Quantitative variation of volatiles compound in ‘Ramassin’ and ‘Sanacore’ after
storage in MA.
0
5
10
15
20
25
30
35
12345678910
PEAKS
%compound/%Total
%c pou in fresh
fru
o
it
m
nd
% compound after
storage under MA
0
5
10
15
20
25
30
151
Ramassin Sanacore
4
15 36 37 38 58 59 71 72
% compound / %Total
PEAKS
1152
