84

1. Introduction

‘Abbé Fétel’ is the most important pear cultivar in Italy 
in terms of production (CONERPO, 2010) and it can be 
stored in normal air (NA) for three to four months and in 
controlled atmosphere (CA) for up to six months (Bai et 
al., 2009). However, when stored in NA for more than four 
months ‘Abbé Fétel’ pears became sensitive to superficial 
scald (Vanoli et al., 2008). ‘Conference’ pears in Italy are 
often subjected to superficial scald in cold storage, and it 
has been reported that under predisposing climatic condi-
tions, up to 70% of fruit developed scald, thus impairing 
their marketability (Folchi and Bertolini, 2008).

Scald is manifested as brown or black patches on the 
skin; it can take several forms and, along with superficial 
scald, it is an expression of damage and/or death within the 
surface layers of cells (Lurie and Watkins, 2012; Whitaker, 
2013). Scald has been related to the presence of oxida-
tion products [conjugated trienols (CTols), primarily α-
farnesene], acting on epidermal cells (Whitaker, 2007) and 

could be prevented or controlled by storage in CA (Berto-
lini et al., 1997; Lurie and Watkins, 2012). However, the 
low levels of oxygen used in CA for ‘Abbé Fétel’ pears 
can induce soft scald (Bertolini et al., 2002; Rizzolo et al., 
2010; Vanoli et al., 2010 a).

Up to now, the traditional strategy to prevent superficial 
scald in pears is a pre-storage treatment with ethoxyquin, 
which recently has been excluded from the list of active 
ingredients of chemicals used in food production (EC 
Council Directive 91/414) (Calvo and Kupferman, 2012). 
The most effective alternatives to ethoxyquin are treatment 
at harvest with 1-methylcyclopropene (1-MCP) or storage 
under controlled atmosphere with low levels of O

2
 such as 

ultra-low oxygen, initial low oxygen stress, and dynamic 
controlled atmosphere (Calvo and Kupferman, 2012; Lu-
rie and Watkins, 2012).

It was found that 1-MCP inhibited superficial scald and 
prevented or controlled soft scald and internal breakdown 
in ‘Bartlett’ pears (Villabolos-Acuña et al., 2011 a, b). In 
‘Conference’ doses ranging from 50 to 1000 µL L–1 did 
not prevent the formation of superficial scald, both in CA 
and in NA, but either controlled it, keeping the incidence 
of scald within commercially acceptable rates, or reduced 
symptom severity (Eccher Zerbini et al., 2003; Rizzolo 

‘Conference’ and ‘Abbé Fétel’ pears treated with 
1-methylcyclopropene: physiological and quality 

implications of initial low oxygen stress and controlled 
atmosphere storage

M. Vanoli, M. Grassi, G. Bianchi, M. Buccheri, A. Rizzolo*
Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Unità di ricerca per i processi 
dell’industria agroalimentare (CREA-IAA), via G. Venezian 26, 20133 Milano, Italy.

Key words:  α-farnesene, ethylene production, fermentative metabolites, pulp mechanical properties, sensory profiles, storage 
disorders.

Abstract: Superficial scald is a disorder developed in cold storage by ‘Conference’ and ‘Abbé Fétel’ pears and it has been 
related to the presence of oxidation products, mainly conjugated trienols (CTols), of which α-farnesene is primary, acting 
on epidermal cells. Among tested postharvest methods to control scald, there is treatment at harvest with 1-methylcy-
clopropene (1-MCP) and initial low oxygen stress (ILOS). The investigation presented here studied, in ‘Conference’ and 
‘Abbé Fétel’ pears treated with 1-MCP (300 μL L–1), the physiolological and quality implications of  storage in controlled 
atmosphere (CA, 2 kPa O2 + 0.7 kPa CO2, -0.5°C) after two 2-weeks ILOS (0.3-0.5 kPa O2) periods at three-week intervals 
after 13 and 21 weeks of storage and shelf life at 20°C up to seven days. Results showed that 1-MCP treatment severely 
reduced α-farnesene, CTol269, CTol281 and ethanol after ILOS treatment in both cultivars, and ethyl acetate in ‘Abbé Fétel’ 
pears. Furthermore, it impaired fruit softening, delayed skin yellowing and reduced ethylene production in shelf life. At 
sensory analyses, 1-MCP treated ‘Conference’ and ‘Abbé Fétel’ pears were described as being firmer and less juicy, sweet 
and aromatic than untreated fruit. 1-MCP treated pears did not develop superficial scald and soft scald in ‘Abbé Fétel’, 
nor superficial scald and black speck after 21 weeks of storage in ‘Conference’.

Adv. Hort. Sci., 2015 29(2-3): 84-96

* Corresponding author: anna.rizzolo@entecra.it

Received for publication 26 September 2014
Accepted for publication 11 May 2015



85

Vanoli et al., ‘Conference’ and ‘Abbé Fétel’ pears treated with 1-methylcyclopropene

et al., 2005; Folchi and Bertolini, 2008). The reduction 
of symptom severity in ‘Conference’ fruit was related to 
lower amounts of α-farnesene and CTols (Rizzolo et al., 
2005; Folchi and Bertolini, 2008). In ‘Abbé Fétel’ pears, 
after shelf life, CTols and α-farnesene were significantly 
higher in fruit affected by superficial scald and lower in 
those affected by senescent scald (Vanoli et al., 2010 b).

Storage under controlled atmosphere with a low level 
of O

2
 was suggested as an alternative to ethoxyquin and 

to 1-MCP treatment not only in controlling scald develop-
ment but also in improving overall fruit quality (Prange 
et al., 2011; Lurie and Watkins, 2012). Widespread adop-
tion of low O

2
 regimes has not taken place due to concerns 

of anaerobic damage when fruit is held below the lower 
oxygen limit (LOL), that is the environmental O

2
 level at 

which cell metabolism changes from being predominantly 
aerobic to fermentative (Wright et al., 2012). Zerbini and 
Grassi (2010) and Rizzolo et al. (2008, 2010) found that 
LOL for ‘Conference’ pears was 0.4 kPa O

2
 and for ‘Abbé 

Fétel’ pears 0.6 kPa O
2
. Vanoli et al. (2008, 2010 a) and Riz-

zolo et al. (2010) found that storage of ‘Abbé Fétel’ pears at 
0.7 kPa O

2
 at -0.5°C completely prevented superficial scald 

development and reduced soft scald incidence compared 
to 2 kPa O

2
, but increased internal browning and internal 

breakdown. As for the initial low oxygen stress, Wang and 
Dilley (2000) found that an ILOS with 0.25 kPa O

2
 for two 

weeks, carried out one or two times at two-month intervals, 
strongly inhibited α-farnesene and its volatile oxidation 
product (6-methyl-5-hepten-2-one), increased ethanol, and 
was effective in controlling scald development in several 
apple cultivars. As for pears, Calvo et al. (2002) found that 
ILOS (0.5 kPa O

2
) followed by low oxygen CA (1.5 kPa O

2
) 

significantly inhibited the development of superficial scald 
after nine months of storage in ‘Beurré d’Anjou’ cultivar, 
while Rizzolo et al. (2015) reported that in ‘Conference’ 
pears after an ILOS (0.2-0.5 kPa O

2
) period followed by 

low oxygen CA (2 kPa O
2
) there were lower amounts of 

α-farnesene, CTol
258

 and acetaldehyde, and higher quanti-
ties of ethanol than after CA and NA storage, developing 
less scald than the other atmospheres.

The objective of the present research was to evaluate in 
‘Conference’ and ‘Abbé Fétel’ pears the effect of 1-MCP 
application on fruit stored in a low oxygen CA after two 
two-week ILOS periods at three-week intervals. Physi-
ological aspects (fermentative metabolites, conjugated 
trienols) in storage, and ethylene production, quality and 
sensory characteristic changes with post-storage shelf life 
and storage disorders are discussed.

2. Materials and Methods

The experiment was carried out in 2012 on ‘Confer-
ence’ and ‘Abbé Fétel’ pears (Pyrus communis L.) (about 
1000 fruit/cv) harvested from commercial orchards in the 
Modena province (Italy) on 20 August and 10 September, 
respectively, at a commercial degree of maturity [mean ± 

standard error: ‘Abbé Fétel’: firmness, 62.5±1.3 N; hue, 
104±0.6°; starch hydrolysis, 4.0 ± 0.5 (EUROFRU 1-10 
scale); ‘Conference’: firmness, 71.0±1.6 N; hue, 108.9±0 
.5°; starch hydrolysis, 3.0 ± 0.1 (EUROFRU 1-10 scale)] 
and randomized in 14 boxes. For each cultivar, on the day 
after harvest, half of the fruits were treated with 300 µL L–1 
1-MCP (Smartfresh™, AgroFresh Inc., Rohm and Haas, 
Spring House, PA, USA) and seven boxes of untreated fruit 
were used as control. ‘Conference’ fruits were then put in 
NA at -0.5°C for four weeks before the beginning of ILOS 
periods and CA storage, while for ‘Abbé Fétel’ pears the 
ILOS experiment began two days after the 1-MCP treat-
ment. For both control and 1-MCP treated ‘Conference’ 
and ‘Abbé Fétel’ pears, two ILOS periods at 0.3-0.5 kPa 
O

2
 for about two weeks were applied with a three-week 

interval in CA at 2 kPa O
2
 + 0.7 kPa CO

2
 at -0.5°C. Four 

containers were used, each one dedicated to one sample 
(1-MCP dose and cultivar); the gas composition of each 
container was controlled and checked with centralized 
analyzers, supervised by a specific Fruit Control Equip-
ment software; fluorescence FIRM™ sensors monitoring 
(HarvestWatch™, Satlantic, Canada) was carried out in 
each container from the beginning of the first ILOS period 
till the first storage time (13 weeks). The first ILOS period 
was applied from d0 to d17, and the second one from d40 
to d53. Then pears were stored in CA at -0.5°C in 2 kPa O

2
 

+ 0.7 kPa CO
2
 up to 21 weeks.

Samplings
α-farnesene, CTols and fermentative metabolites were 

analyzed (6 fruits/1-MCP dose/cultivar) at the beginning 
and at the end of the second ILOS period, and at the first 
storage time (13 weeks); hereafter these samplings are re-
ferred as d0, d13 and d40. 

After 13 and 21 weeks of storage, 3 boxes/1-MCP dose/
cultivar were put in shelf life at 20 °C up to 7 days. At 1, 5 
and 7 days of shelf life (d1, d5, d7) 20 fruit/1-MCP dose/
cultivar were analyzed for background skin color and pulp 
mechanical properties (firmness, stiffness and energy-to-
rupture). Ethylene production was measured at d1, d5 and 
d7 on ten fruits of sample d7, while sensory analyses were 
carried out on ten fruits at d5 and d7. After 7 days at 20 
°C the incidence of storage disorders was evaluated on 3 
boxes/1-MCP dose/cultivar.

α-Farnesene and CTols
α-Farnesene and CTols (CTol

258
, CTol

269
, CTol

281
) were 

determined in the skin according to Zoffoli et al. (1998), by 
sampling eight skin disks of 0.8 cm2 area from the equato-
rial region of two pears (three replications) and extracting 
overnight at 2°C with 6 mL of HPLC-grade hexane with 
1 g of anhydrous Na

2
SO

4
. The absorbance of the extracts 

at 232, 258, 269, 281 and 290 nm was measured using 
a Jasco (model 7800) spectrophotometer. Concentrations 
of α-farnesene and CTols were calculated according to 
Huelin and Coggiola (1970) and Du and Bramlage (1993). 
Data were expressed as nmol cm–2.



86

Adv. Hort. Sci., 2015 29(2-3): 84-96

Fermentative metabolites
Fermentative metabolites (ethanol, acetaldehyde and 

ethyl acetate) were determined on the pulp of the same 
fruit analyzed for α-farnesene and CTols by means of HS-
SPME-GC, by pooling the six fruits of each sample. Ten 
grams of homogenized pulp (three replications) were put 
into 25 mL vials tightly closed with an aluminum cap with 
a silicone-Teflon rubber septum; samples were then im-
mediately frozen and kept at -20°C until analysis. After 60 
min thawing at room temperature, the SPME headspace 
volatile sampling was carried out for 30 min at 40°C using 
a 50/30µm DVB-CAR-PDMS fiber (Supelco), which was 
desorbed for 5 min in the GC injector port at 250°C. Fer-
mentative metabolites were separated on a Supelcowax-10 
column (60 m ×0.25 mm I.D., 0.25 µm film thickness) us-
ing the following conditions: carrier gas, helium at a flow 
of 1.5 mL min–1; temperature program, 40°C×13 min, 
15°C min–1 to 185°C; FID temperature, 250°C. Fermenta-
tive metabolites were quantified by relating the peak area 
of each one to that of external standards.

Background skin color
Background skin color was measured on the greener 

side of fruit with a Spectrophotometer CM-2600d (Mi-
nolta Co, Japan) using the primary illuminant D65 and 10° 
observer in the L*, a*, b* color space. From a* and b* val-
ues, hue (H°) and chroma (C*) were computed according 
to H°=arctan (b* a*–1) and C*= (a*2 + b*2)−2.

Pulp mechanical properties
The mechanical properties of pear tissue of each fruit 

were measured on two opposite peeled areas in the equa-
torial region of the pear using an 8 mm diameter plunger 
mounted on an Instron Universal Testing Machine (model 
4301, Instron Ltd, Great Britain) with crosshead speed at 
200 mm min–1. From the force-displacement curve the fol-
lowing pulp mechanical properties were measured (Riz-
zolo et al., 2014): firmness (N), stiffness (N mm–1) and 
energy-to-rupture (mJ). Firmness, stiffness and energy-to-
rupture readings were averaged for each fruit.

Ethylene production rate
The ethylene production rate (EP) was measured by 

static HS/GC on fruit put in 1.7 L gas-tight glass jars (ten 
replications, one fruit per jar) for 2 h at 20 °C according to 
Rizzolo et al. (2005). One milliliter of the headspace gas 
was sampled and analyzed using a deactivated aluminum 
oxide F1 (80-100 mesh) column (1/8 in 200 cm) at a col-
umn temperature of 100°C and FID detection. Quantita-
tive data were obtained by relating the ethylene peak area 
to that of a 10 μL L–1 standard and were expressed as pmol 
kg–1 s–1.

Sensory analysis
Sensory analyses were carried out in a sensory lab us-

ing a panel of ten short-term trained judges at d5 and d7 
of shelf life at 20°C. For both the cultivars in each session, 

one peeled slice/1-MCP dose was presented to each panel-
ist. At the beginning of the session, a slice of a fruit not in-
cluded in the experimental plan was tasted to eliminate the 
first tasting effect. Drinking water was provided as a palate 
cleaner between samples. Each sample was evaluated for 
the intensity of attributes related to fruit structure (firm, 
juicy, grainy) and taste and flavor (sweet, sour, aromatic, 
bitter, astringent) using 120 mm unstructured line scales 
with anchors at 12 mm from the extremes (low, high). In 
addition, in order to have a rough idea of sample pleas-
antness, at the end of the tasting session, panelists were 
also asked to score samples for overall acceptability using 
a 120 mm unstructured line scale with “low” and “high” 
anchors near the extremes. Details on panel training and 
attributes are reported by Rizzolo et al. (2014).

Storage disorders
Storage disorders were evaluated on three boxes/1−

MCP dose/cultivar. For each box the percentages of healthy 
fruit and of fruit affected by superficial scald, rots (both 
cultivars), soft scald (‘Abbé Fétel’), early blackening, black 
speck and black spot (‘Conference’) were computed.

Statistical analysis
Data were submitted to analysis of variance (Statgraph-

ics ver.7, Manugistic Inc., Rockville, MD, USA). Prior to 
statistical analysis the rating scores of each sensory attri-
bute were standardized by panelists in order to remove the 
variability due to their using different parts of the scale 
(Bianchi et al., 2009). Percentage data were submitted to 
angular transformation before ANOVA.

3. Results

Oxygen levels and chlorophyll fluorescence
Figure 1 shows the oxygen partial pressure and the cor-

responding response of chlorophyll fluorescence (Fα) for 
control and 1-MCP treated ‘Abbé Fétel’ and ‘Conference’ 
pears from the beginning of the first ILOS period till the 
first storage time (13 weeks). By comparing the graphs 
of O

2
 partial pressure of containers of control and 1-MCP 

treated ‘Conference’ pears, it is evident that during the 
first ILOS period the O

2
 values ranged from about 0.2 to 

0.6 kPa and during the second ILOS from 0.15 to 0.55 
kPa. The two ILOS periods induced a remarkable rise in 
chlorophyll fluorescence (Fα) in untreated fruit and much 
smaller ones in 1-MCP treated pears, when O

2
 concen-

tration decreased below 0.4 kPa. In control ‘Abbé Fétel’ 
pears the O

2 
concentration decreased below 0.6 kPa only 

for a short time during the first ILOS period, while during 
the second ILOS period O

2
 values ranged from 0.3 to 0.6 

kPa, causing a very slight rise in Fα at the end of the sec-
ond ILOS period. On the other hand, in the container with 
1-MCP treated ‘Abbé Fétel’ pears O

2
 values ranged from 

0.1-0.4 kPa during the two ILOS periods, causing a slight 
rise in Fα in coincidence with the two ILOS periods.



87

Vanoli et al., ‘Conference’ and ‘Abbé Fétel’ pears treated with 1-methylcyclopropene

α-Farnesene and conjugated trienols
On average 1-MCP treated ‘Conference’ pears had 

lower amounts of α-farnesene, CTol
269

 and CTol
281

 than 
control fruit, and CTol

281
 at the end of the ILOS period 

(d13) was not detectable in 1-MCP treated fruit (Table 1). 
In control fruit α-farnesene, CTol

269
 and CTol

281
 signifi-

cantly increased at d40, in correspondence wth the first 
storage time. Likewise, 1-MCP treated ‘Abbé Fétel’ pears 

Table 1 -  Amounts (mean ± standard error) of α-farnesene (α-FARN), CTols (CTol
258

, CTol
269

, CTol
281

) and fermentative metabolites (ACE, acetal-
dehyde; EtOH, ethanol; EtAc, ethyl acetate) in control (MCP0) and 1-MCP treated (MCP300) ‘Conference’ pears at the beginning (d0) 
and at the end (d13) of the second ILOS period and in correspondence with the first storage time (d40) and ANOVA results

α-FARN
nmol cm–2

CTol
258

nmol cm–2

CTol
269

nmol cm–2

CTol
281

nmol cm–2

ACE
µg kg–1

EtOH
µg kg–1

Et Ac
µg kg–1

MCP0

d0 11.32±2.97 0.97±0.24 1.16±0.18 0.21±0.08 27.33±5.38 38.77±13.85 0.10±0.05

d13 9.26±2.81 0.80±0.27 0.90±0.22 0.60±0.33 29.15±3.23 69.45±3.71 0.14±0.09

d40 23.04±8.69 1.80±0.60 2.32±0.58 0.91±0.33 35.34±0.29 24.71±1.13 1.77±1.52

MCP300

d0 3.77±0.28 1.01±0.15 1.08±0.12 0.14±0.04 40.26±4.42 55.81±7.39 0.06±0.03

d13 2.96±0.31 0.62±0.15 0.68±0.16  nd 17.31±8.67 21.30±14.83 0.05±0.04

d40 3.90±0.37 0.77±0.15 0.93±0.14 0.04±0.02 33.89±3.82 23.01±2.66 0.87±0.45

ANOVA (z)

A: day ns ns * * ns * ns

B: 1-MCP ** ns * ** ns ns ns

A × B ns ns ns * ns ** ns

(z) ***, P<0.001; **, P<0.01; *, P<0.05; ns, not significant.

Fig. 1 -  Oxygen partial pressure (gray) and corresponding response of chlorophyll fluorescence Fα (black) for control and 1-MCP treated containers 
of ‘Abbé Fétel’ and ‘Conference’ fruit. The dotted lines indicate the O

2
 partial pressure inducing stress evidenced by Fα increase (‘Abbé 

Fétel’ 0.6 kPa; ‘Conference’ 0.4 kPa)



88

Adv. Hort. Sci., 2015 29(2-3): 84-96

had lower amounts of α-farnesene, CTol
258

, CTol
269

 and 
CTol

281
 than control fruit (Table 2). The α-farnesene and 

CTols concentrations did not significantly change from 
the beginning (t0) to the end of the second ILOS period 
(d13) both in control and 1-MCP treated ‘Abbé Fétel’ 
fruit, and then they increased at d40. The concentration of 
α-farnesene in pear skin was three to five times higher in 
control than in 1-MCP treated fruit, those of CTol

258
 and 

CTol
269

 two (‘Conference’) to four-six times (‘Abbé Fé-
tel’), and that of CTol

281
 two to eight times in ‘Abbé Fétel’ 

and fifteen to twenty-three times in ‘Conference’.
In both cultivars the ratios CTol

258
/CTol

281
 and CTol

269
/

CTol
281

 (Fig. 2) were higher in 1-MCP treated fruit than 

in control ones, being, on average, three times higher in 
‘Conference’ pears, and about 50% higher in ‘Abbé Fétel’ 
treated fruit. In ‘Conference’ the highest values for both 
ratios were observed in 1−MCP treated fruit at d 40, while 
in ‘Abbé Fétel’ in 1−MCP treated fruit at d0 and d13. Con-
trol ‘Abbé Fétel’ and ‘Conference’ pears at d40 showed 
the lowest values for both the ratios.

Fermentative metabolites
In ‘Conference’ pears the 1-MCP treatment at harvest 

did not influence the amounts of fermentative metabolites 
(Table 1). In control ‘Conference’ pears ethanol increased 
with the second ILOS period, then it significantly decreased 

Table 2 -  Amounts (mean ± standard error) of α-farnesene (α-FARN), CTols (CTol
258

, CTol
269

, CTol
281

) and fermentative metabolites (ACE, acetal-
dehyde; EtOH, ethanol; EtAc, ethyl acetate) in control (MCP0) and 1-MCP treated (MCP300) ‘Abbé Fétel’ pears at the beginning (d0) and 
at the end (d13) of the second ILOS period and in correspondence with the first storage time (d40) and ANOVA results

α-FARN
nmol cm–2

CTol
258

nmol cm–2

CTol
269

nmol cm–2

CTol
281

nmol cm–2

ACE
µg kg–1

EtOH
µg kg–1

Et Ac
µg kg–1

MCP0

d0 14.80±4.65 0.83±0.14 0.70±0.14 0.42±0.10 10.38±0.31 14.86±5.18 0.92±0.07

d13 15.10±1.41 0.70±0.05 0.63±0.02 0.38±0.01 16.40±3.56 31.10±6.65 0.08±0.06

d40 55.14±9.81 3.83±0.53 6.41±0.91 5.14±0.79 26.78±6.56 39.62±15.98 0.06±0.01

MCP300

d0 2.51±0.08 0.43±0.05 0.34±0.06 0.18±0.03 14.03±2.83 17.89±5.11 0.51±0.03

d13 2.69±0.06 0.47±0.01 0.34±0.01 0.18±0.01 16.21±2.10 34.94±5.34 0.09±0.05

d40 10.91±1.94 1.01±0.30 1.01±0.32 0.62±0.17 27.33±3.04 48.99±11.30 0.04±0.02

ANOVA (z)

A: day *** *** *** *** *** * ***

B: 1-MCP *** *** *** *** ns ns **

AxB ** *** *** ns ns ns ***

(z) ***, P<0.001; **, P<0.01; *, P<0.05; ns, not significant.

Fig. 2 -  CTol
258

/CTol
281

 and CTol
269

/CTol
281

 ratios of control (MCP0) and 1–MCP treated (MCP300) ‘Abbé Fétel’ and ‘Conference’ pears at the 
beginning (d0) and the end (d13) of the second ILOS period and in correspondence with the first storage time (d40). Bars refer to standard 
error of the mean.



89

Vanoli et al., ‘Conference’ and ‘Abbé Fétel’ pears treated with 1-methylcyclopropene

at d40 (i.e. 13 weeks storage time), while in 1-MCP treated 
fruit it decreased with the second ILOS period and did not 
change further at d40. The sampling time had no significant 
influence on acetaldehyde and ethyl acetate amounts both 
in control and 1-MCP treated fruit, probably due to the high 
standard errors of data, especially for ethyl acetate. 

The 1-MCP treated ‘Abbé Fétel’ pears (Table 2) had, 
on average, lower ethyl acetate amounts at d0 than con-
trol fruit. Ethyl acetate both in control and 1-MCP treated 
pears decreased steeply with the ILOS period, and after-
wards did not change at d 40. Both in control and 1-MCP 
treated ‘Abbé Fétel’ fruit acetaldehyde concentration did 
not change from the beginning (d0) to the end of the sec-
ond ILOS period (d13), and then increased at d40, while 
ethanol increased throughout the sampling time. 

Ethylene production
Ethylene production in control ‘Conference’ pears was 

lower than in ‘Abbè Fétel’ (Fig. 3). In ‘Conference’ pears 
EP was significantly affected only by the 1-MCP treat-
ment (Table 3), whereas in ‘Abbé Fétel’ fruit both 1-MCP 
treatment and post storage shelf life significantly influ-
enced EP (Table 3). In both cultivars the 1-MCP treatment 
reduced EP to values lower than 10 pmol kg–1 s–1. In ‘Abbé 
Fétel’ control and 1-MCP treated fruit after 13 weeks stor-
age showed a decreasing EP with shelf life, and after 21 
weeks a minimum EP at d5.

Pulp mechanical characteristics
Upon removal, 1-MCP treated ‘Conference’ and ‘Abbé 

Fétel’ pears maintained firmness similar to that at harvest 
(‘Conference’: 71.0±1.6 N; ‘Abbé Fétel’: 62.5±1.3 N), but 
lower stiffness and higher energy-to-rupture than at har-
vest (values at harvest: stiffness: ‘Conference’, 21.0±0.5 N 
mm−1; ‘Abbé Fétel’, 24.5±0.6 N mm−1; energy-to-rupture: 
‘Conference’, 0.106±0.04 J; ‘Abbé Fétel’, 0.074±0.003 
J). The same scenario was found for control ‘Conference’ 
pears, whereas control ‘Abbé Fétel’ fruit had lower firm-
ness and energy-to-rupture than at harvest.

On average, 1-MCP treated ‘Conference’ pears had 
higher firmness, stiffness and energy-to-rupture than con-

trol fruit, without any difference between storage times; 
firmness and energy-to-rupture did not change with shelf 
life, whereas stiffness decreased, but to a lesser extent than 
control fruit (Fig. 4). In control ‘Conference’ pears the val-
ues of all the mechanical properties decreased with shelf 
life with the main changes at d5.

As for ‘Abbé Fétel’ pears (Fig. 4), on average, 1-MCP 
treated fruit showed higher firmness, stiffness and ener-
gy-to-rupture than control fruits, without any difference 
between the storage times, except for a higher energy-to-
rupture of 1-MCP treated fruit after 21 weeks of storage.

Fig. 3 -  Ethylene production rate (EP) of control (left) and 1–MCP 
treated (right) ‘Abbé Fétel’ and ‘Conference’ pears during shelf 
life at 20°C after 13 and 21 weeks of storage. Bars refer to stan-
dard error of the mean. Results of ANOVA analysis are reported 
in Table 3.

Table 3 -  Multifactor ANOVA results for pulp mechanical characteristics (firmness, F, stiffness, St and energy-to-rupture, E
f
), color parameters 

(lightness, L*; chroma, C* and hue) and ethylene production rate (EP) for ‘Abbé Fétel’ and ‘Conference’ pears

Abbé Fétel Conference

EP F St E
f

L* C* Hue EP F St E
f

L* C* Hue

A: storage time ns ns ns *** ns ** *** ns ns ns ns *** *** ***

B: 1-MCP *** *** *** *** *** *** *** *** *** *** *** *** *** ***

C: shelf life *** *** *** *** *** *** *** ns *** *** *** *** *** ***

A×B ns ns * ns * ns ns ns ns ns ns ns ns *

A×C ns * ns * ns ns ns ns * ns ** ns ns ns

B×C *** *** *** *** ns ns * ns *** *** *** ** * *

A×B×C ns ** ** * ns ns ns ns ns ns ns ns ns ns

***, P<0.001; **, P<0.01; *, P<0.05; ns, not significant)



90

Adv. Hort. Sci., 2015 29(2-3): 84-96

At d1 of shelf life, control ‘Abbé Fétel’ pears had lower 
firmness and energy-to-rupture but similar stiffness than d1 
1-MCP treated fruit. Firmness, stiffness and energy-to-rup-
ture of control ‘Abbé Fétel’ pears decreased after 5 days and 
then they did not change further. In 1-MCP treated ‘Abbé 
Fétel’ pears, firmness and energy-to-rupture did not change 
with shelf life, whereas stiffness decreased after 5 days, but 
to a lesser extent than in control fruit, without any further 
change with the increase of shelf life time.

Skin color
On average in ‘Conference’ pears L* and C* were 

higher in control fruit after 21 weeks storage (Fig. 5) than 
in 1-MCP treated fruit at both storage times and in con-
trol fruits after 13 weeks storage, while the highest H° was 
found for 1-MCP treated fruit at both storage times and the 
lowest for control fruit after 21 weeks. Hue decreased with 
storage time only in control fruit. At d1 of shelf life control 
‘Conference’ pears had L*, C* and H° values not different 
from those of 1-MCP treated fruit. With shelf life, L* and 
C* increased and H° decreased both in control and 1-MCP 
treated fruit, with control fruit at d7 showing the highest 
values of L* and C* and the least of H°.

In ‘Abbé Fétel’ the highest L* value was found in 
control fruit after 13 weeks of storage and the lowest in 
1-MCP treated fruit at both storage times (Fig. 5). Chroma 
on average was higher in control fruit than in 1-MCP treat-
ment without any influence of storage time, whereas H° 
was higher in 1-MCP treated fruit than in control pears, 

without any difference between storage times, with control 
fruits having the lowest H° value after 21 weeks storage. 
At d1 of shelf life control ‘Abbé Fétel’ pears had higher 
L* and lower H° than 1-MCP treated fruit. L* increased 
with shelf life in control fruit at both storage times and 
in 1-MCP treated ones after 21 weeks of storage. H° de-
creased with shelf life only in control fruit, while C* in-
creased both in control and 1-MCP treated fruit, with con-
trol fruit having the highest values at d7.

Sensory analysis
With regard to sensory analysis, ‘Conference’ 1-MCP 

treated pears were on average firmer, more grainy, less 
juicy, sweet, sour and aromatic than control ones (Fig. 
6), with the average scores being (1-MCP and control, re-
spectively): 84 and 45 for sensory firmness, 52 and 38 for 
graininess, 25 and 71 for juiciness, 47 and 62 for sweet-
ness, 19 and 24 for sourness, and 33 and 59 for aromatic. 
No changes in sensory profile with storage time and shelf 
life were observed for 1-MCP treated ‘Conference’ pears. 
In contrast, in control ‘Conference’ pears sensory firm-
ness decreased during shelf life, without any differences 
between the storage times, while sweetness decreased 
with shelf life after 13 weeks storage and increased af-
ter 21 weeks storage, with d5 pears after 13 weeks being 
sweeter than fruit after 21 weeks. Juiciness in control fruit 
increased with shelf life only after 13 weeks storage and it 

Fig. 4 -  Firmness, stiffness and energy-to-rupture of control (MCP0) 
and 1-MCP treated (MCP300) ‘Abbé Fétel’ and ‘Conference’ 
pears after 1, 5 and 7 days of shelf life at 20°C after 13 and 21 
weeks of storage. Bars refer to standard error of the mean. Re-
sults of ANOVA analysis are reported in Table 3.

Fig. 5 -  Lightness (L*), chroma (C*) and hue angle (degree) of control 
(MCP0) and 1-MCP treated (MCP300) ‘Abbé Fétel’ and ‘Con-
ference’ pears after 1, 5 and 7 days of shelf life at 20°C after 
13 and 21 weeks of storage. Bars refer to standard error of the 
mean. Results of ANOVA analysis are reported in Table 3.



91

Vanoli et al., ‘Conference’ and ‘Abbé Fétel’ pears treated with 1-methylcyclopropene

was not significantly affected by the storage time. Overall 
acceptability was higher in control fruit and it was not in-
fluenced by storage time and shelf life both in control and 
1-MCP treated ‘Conference’ fruit.

On average control ‘Abbé Fétel’ pears were less firm 
and more juicy, sweet and aromatic than 1-MCP treated 
fruit, the average scores being (1-MCP and control, re-
spectivley): 93 and 50 for sensory firmness, 33 and 58 
for juiciness, 43 and 59 for sweetness, and 33 and 50 for 
aromatic. Similarly to that found for ‘Conference’ pears, 
control ‘Abbé Fétel’ fruit at d5 of shelf life (Fig. 6) were 
firmer than at d7, without any influence of storage time. 
Juiciness was higher in d7 fruit after 13 weeks storage than 
in those after 21 weeks. Sweetness and aromatic scores 

were lower in d5 fruit after 21 weeks than in d5 ones af-
ter 13 weeks, the latter showing also higher sourness and 
astringency than fruit stored for 21 weeks at the end of 
shelf life. As for 1-MCP treated ‘Abbé Fétel’ pears, sen-
sory firmness did not change with shelf life in fruit stored 
for 13 weeks, whereas it increased in those stored for 21 
weeks, with the d7 fruit after 21 weeks being firmer than 
fruit at d5 of both storage times. 1-MCP treated ‘Abbè Fé-
tel’ pears at d5 after 13 weeks of storage were less firm 
and juicier and sweeter than those of the same storage time 
at d7 and than those stored for 21 weeks. Overall accept-
ability decreased with storage time and shelf life: control 
fruit after 13 weeks storage and 5 days of shelf life had the 
highest overall acceptability, while 1-MCP treated fruit at 

Fig. 6 -  Sensory profiles and overall acceptability of control (MCP0) and 1-MCP treated (MCP300) ‘Abbé Fétel’ and ‘Conference’ pears after 13 
and 21 weeks of storage and 5 (d5) and 7 (d7) days of shelf life at 20°C. Within each 1-MCP dose, for each attribute the significance of F-
ratio (**, P<0.01; *, P<0.05; (*), P<0.10; no symbol, not significant) is reported. Within each 1-MCP dose, bars with different letters refer 
to statistically different means (Tukey’s test, P < 0.05%).



92

Adv. Hort. Sci., 2015 29(2-3): 84-96

d7 after 13 weeks and at d5 and d7 after 21 weeks stor-
age had the least overall acceptability. In addition, 1-MCP 
treated ‘Abbé Fétel’ pears stored for 13 weeks at 5 days of 
shelf life had an overall acceptability score that was not 
different from that of control fruit stored for 21 weeks. 

Storage disorders
In ‘Conference’ pears at the end of storage and after 

7 days at 20°C the percentage of healthy fruit was very 
low and decreased with storage time both in control and 
1-MCP treated fruit (Table 4). Three types of peel disor-
ders were detected: blackening, superficial scald and black 
speck. Two forms of blackening were distinguishable, 
differing for the color and severity of the disorder: early 
blackening, characterized by a grey net covering part of 
the peel, without any specific localization, and black spot, 
characterized by a very tight black net which, in the most 
severe forms, covered almost all the fruit surface. The per-
centages of fruit affected by the two forms of blackening 
were very high (Table 4). Early blackening was found only 
after 13 weeks of storage and its incidence was not in-
fluenced by 1-MCP treatment; black spot was found only 
after 21 weeks of storage, with higher incidence in 1-MCP 
treated fruit than in control ones. Superficial scald inci-
dence was low (less than 5%) and developed only in con-
trol fruit after 21 weeks of storage. Black speck incidence 
was low (about 5%) and was found both in control and 
1-MCP treated pears after 13 weeks of storage. Rot inci-
dence was very low and was influenced neither by storage 
time nor by the 1-MCP treatment.

In ‘Abbé Fétel’ pears the percentage of healthy fruit 
on average was 93.3% in 1-MCP treated fruit and 77.4% 
in control ones and slightly decreased with storage time 
(Table 5). Two types of peel disorders were detected: soft 
scald and superficial scald, both of them developed only in 
control fruit. The incidence of soft scald increased some-
what with the increase of storage time, while superficial 
scald was detected at percentages lower than 1.5% only 
after 21 weeks of storage. Rot incidence was low, ranging 

from 4.2% (1-MCP treated after 21 weeks) to 8.6% (con-
trol after 21 weeks), and was not significantly influenced 
by storage time nor by the 1-MCP treatment.

4. Discussion

In control and 1-MCP treated ‘Conference’ pears, the 
two ILOS periods induced a remarkable rise in chlorophyll 
fluorescence (Fα) in untreated fruit and much smaller ones 
in 1-MCP treated pears, when O

2
 concentration decreased 

below 0.4 kPa, which is the lower O
2
 limit (LOL) at which 

metabolism of ‘Conference’ pears changes from aerobic 
to fermentative (Zerbini and Grassi, 2010). The lesser Fα 
increase found in 1-MCP treated ‘Conference’ pears could 
be due to respiration reduction induced by 1-MCP, which 
reduces LOL, as observed in other pear cultivars (Watkins, 
2006) and in ‘Abbé Fétel’ fruit by Rizzolo et al. (2008, 
2010). In control ‘Abbé Fétel’ pears the O

2 
concentration 

decreased below 0.6 kPa, which is its LOL, only for a short 

Table 4 -  Storage disorders in control (MCP0) and 1-MCP treated (MCP300) ‘Conference’ pears after 13 and 21 weeks of storage and 7 days of 
shelf life at 20°C and ANOVA results  (n=3)

healthy
Early

blackening
Black
spot

Superficial
scald

black
speck

rot

MCP0

13 w 33.2 ±0.3 59.4±0.7 0 0 4.6 ±0.4 0.3±0.1

21 w 22.2±0.4 0 71.3±0.3 4.7±0.4 0 0.3±0.3

MCP300

13 w 29.0±0.01 64.3±0.01 0 0 5.3±0.01 1.3±0.01

21 w 10.8±0.2 0 88.4±0.2 0 0 0.5±0.1

ANOVA (z)

A: storage time ** *** *** ** *** ns

B: 1-MCP ns ns * ** ns ns

A × B ns ns * ** ns ns

(z) ***, P<0.001; **, P<0.01; *, P<0.05; ns, not significant.

Table 5 -  Storage disorders in control (MCP0) and 1-MCP treated 
(MCP300) ‘Abbé Fétel’ pears after 13 and 21 weeks of stor-
age and 7 days of shelf life at 20°C and ANOVA results (n=3)

Healthy Soft scald
Superficial

scald
rot

MCP0

13 w 82.5±0.3 10.6±0.1 0 5.6±0.2

21 w 72.8±0.1 15.1±0.2 1.4±0.4 8.6±0.2

MCP300

13 w 95.6±0.03 0 0 4.4±0.03

21 w 91.5±0.2 0 0 4.2±1.2

ANOVA (z)

A: storage time * ns ns ns

B: 1-MCP *** *** ns ns

A × B ns ns ns ns

(z) ***, P<0.001; *, P<0.05; ns, not significant.



93

Vanoli et al., ‘Conference’ and ‘Abbé Fétel’ pears treated with 1-methylcyclopropene

period during the first ILOS period, while during the sec-
ond ILOS period O

2
 values ranged from 0.3 to 0.6 kPa. In 

contrast, in the container with 1-MCP treated ‘Abbé Fétel’ 
pears during the two ILOS periods O

2
 values ranged from 

0.1-0.4 kPa, causing a slight rise in Fα in 1-MCP treated 
‘Abbé Fétel’ pears probably due to the fact that in this con-
tainer the O

2
 values were much lower than the LOL value.

It has been reported that fruit stored in ultralow oxy-
gen pressure, below 2 kPa inducing fermentation, when 
compared to fruit stored in air develop lower quantities of 
straight-carbon chain compounds, esters, aldehydes and 
ketones (Mattheis et al., 1991, Fellman et al., 1993) and 
increased amounts of ethanol, acetaldehyde and ethanol-
derived ethyl esters, mainly ethyl acetate (Argenta et al., 
2004). Furthermore, Lumpkin et al. (2014) found for ap-
ples that acetaldehyde, ethanol and ethyl esters amounts 
increased with pO

2
, decreasing from 1.5 kPa to 0.3 kPa, 

mainly during the first weeks of storage, while Mattheis 
et al. (2013) found in ‘d’Anjou’ pears a significant cor-
relation between pithy brown core incidence and ethanol, 
suggesting a relationship between disorder development 
and abnormal oxidative metabolism due to an hypoxic 
storage environment. According to these findings we can 
infer that, in control ‘Conference’ pears and in control and 
1-MCP treated ‘Abbé Fétel’ fruit, the stress due to the low 
pO

2
 applied during the ILOS period, as highlighted by the 

fluorescence monitoring, impacted on fermentative me-
tabolites. The reduction of respiration induced by 1-MCP 
significantly influenced fermentative metabolite develop-
ment, as in ‘Conference’ no more ethanol was produced 
during the low pO

2
 ILOS period and in ‘Abbè Fètel’ pears 

it lowered the production of ethyl acetate.
As for the relationships between ILOS period and α-

farnesene and CTols content in the peel, for both cultivars 
no significant changes in their concentrations following the 
ILOS period were found, with the exception of CTol

281
 in 

1-MCP treated ‘Conference’ pears, which became not de-
tectable at the end of the ILOS period. Then, after 13 weeks 
of storage α-farnesene and CTols concentration in the peel 
increased in control fruit of both cultivars and in 1-MCP 
treated ‘Abbé Fétel’ pears. On the other hand, in both culti-
vars 1-MCP treatment significantly inhibited the production 
of α-farnesene and CTols not only during the ILOS period 
but also after the CA storage period till 13 weeks storage 
time, with ‘Abbé Fétel’ pears showing a more marked re-
duction in α-farnesene, CTol

258
 and CTol

269
 concentrations 

and ‘Conference’ fruit in CTol
281

 concentration.
The α-farnesene and CTols trends observed are in agree-

ment with previous findings on ‘Conference’ and ‘Abbé 
Fétel’ pears (Lo Scalzo et al., 2002; Folchi and Bertolini, 
2008; Eccher Zerbini et al., 2005; Vanoli et al., 2010 b) 
and could be due to the fact that low temperature storage 
induces, in scald-susceptible cultivars, a high rate of α-
farnesene synthesis, which causes its marked accumulation 
in the skin during the first two to three months of storage. 
Then, the concentration of α-farnesene declines as a con-
sequence of its in vivo oxidation to the highly reactive con-

jugated trienols (Gapper et al., 2006; Isidoro and Almeida, 
2006; Whitaker, 2007), which disrupt cell membranes and 
lead to polyphenoloxidase-mediated browning of the skin 
(Bain and Mercer, 1963) and necrosis of the hypodermal 
cell layers. Moreover, it was found that both in apples and 
pears inhibition of α-farnesene synthesis by 1-MCP was 
closely correlated with suppression of the α-farnesene 
synthase gene PcAFS1, which encodes the last enzyme in 
the α-farnesene biosynthetic pathway (Lurie et al., 2005; 
Pechous et al., 2005; Gapper et al., 2006). In highly scald-
susceptible apple and pear cultivars, inhibition of ethyl-
ene production and α-farnesene synthesis by pre-storage 
1-MCP treatment is often lost after several months in cold 
storage, and this coincides with loss of scald control (Gap-
per et al., 2006; Tsantili et al., 2007). For ‘d’Anjou’ pears 
Zoffoli et al. (1998) reported that CTol

269
 was the main peak 

for conjugated trienols and increased during cold storage, 
as did the other two CT peaks; also for ‘Packham’s Tri-
umph’ pears the three CTols increased during storage, but 
CTol

258
 was proportionally higher than CTol

281
 and almost 

the same as CTol
269

, while in ‘Bartlett’ pears the main CTol 
was CTol

258
, which increased with storage, with very low 

amounts for the other two CTols. Whitaker et al. (2001) 
associated the absorbance measured at 258 nm in the skin 
hexane extracts to a family of p-cumaryl fatty esters which 
act as antioxidant rather than to an oxidation product of 
α-farnesene. In view of these findings, our results sug-
gest that the capacity of ‘Conference’ pears stored in CA 
after ILOS periods to generate scald-related antioxidants 
(CTol

258
) is higher than the fruit’s ability to produce scald-

related α-farnesene oxidation products (CTol
281

), while the 
opposite scenario was found for control ‘Abbè Fétel’ fruit. 
Considering the ratio CTol

258
/CTol

281
, a potential marker 

of superficial scald, Du and Bramlage (1993) found that 
values lower than 1.0 were generally associated to high 
scald susceptibility while values greater than 2.0 were as-
sociated to lower scald susceptibility. In this work, higher 
values of CTol

258
/CTol

281 
were found in 1-MCP treated 

fruit of both cultivars, whereas values below 1.0 and below 
2.0 were found in control fruits of ‘Abbé Fétel’ and ‘Con-
ference’, respectively, both developing some superficial 
scald at the end of storage. Du and Bramlage (1993) re-
ported that CTol

269
/CTol

281
 ratio values generally reflected 

those of the CTol
258

/CTol
281

 ratio, but differences were less 
distinct when comparing lots of apple fruit with different 
scald potential. On the other hand, Zoffoli (1994), when 
considering the trends of the CTol

258
/CTol

281
 and CTol

269
/

CTol
281 

ratios with cold storage time in pears, suggested 
that CTol

258
 could be the precursor to

 
CTol

269
, and CTol

269 
the precursor to

 
CTol

281
. In the present study, data of the 

two ratios confirmed Zoffoli’s (1994) hypothesis: indeed 
in ‘Abbé Fétel’ pears at the beginning and at the end of the 
second ILOS period CTol

258
 was predominant, both in con-

trol and 1-MCP treated fruit, but in correspondence with 
the first storage time CTol

269
 was predominant in control 

fruit, while it was almost the same in 1-MCP treated pears. 
Similarly, in control ‘Conference’ fruit at the first storage 



94

Adv. Hort. Sci., 2015 29(2-3): 84-96

time, CTol
269

 was predominant. The low incidence of su-
perficial scald found in this work could be due either to 
seasonal non predisposing conditions, as low superficial 
scald incidence was observed in ‘Abbé Fétel’ fruit stored 
in NA (Rizzolo, Grassi and Vanoli unpublished) or to the 
beneficial effect of CA in ‘Conference’ pears with respect 
to NA stored fruit (Rizzolo et al., 2015).

Both in ‘Conference’ and ‘Abbé Fétel’ pears, 1-MCP 
treatment prevented the development of scald after storage 
and shelf life. In ‘Conference’ a high proportion of fruit 
developed blackening in a less severe form after 13 weeks 
storage, and with higher incidence and severity after 21 
weeks storage. Blackening has been detected in ‘Con-
ference’ pears for about twenty years, but its incidence 
and severity has been increasing over the last few years. 
According to previous observations (Bertolini, personal 
communication), blackening development is not related 
to α-farnesene and CTols development and it is neither 
controlled nor prevented by 1-MCP treatment, rather it 
induced higher severity than in control fruit. Black speck 
was developed in ‘Conference’ only after 13 weeks storage 
and, similarly to blackening, it was neither controlled nor 
prevented by 1-MCP treatment. Black speck has been re-
ported for mature-green ‘d’Anjou’ pears (Lee et al., 1990) 
and it was suggested that it is provoked by fruit stress re-
lated to low temperature in conjunction with low oxygen 
CA storage, as confirmed by Mattheis and Rudell (2011), 
who found that the low O

2
 partial pressure set points es-

tablished by monitoring fruit chlorophyll fluorescence can 
prevent ‘d’Anjou’ scald but may result in black speck de-
velopment.

The pre-storage 1-MCP treatment drastically reduced 
ethylene production during post-storage shelf life both 
in ‘Conference’ and ‘Abbé Fétel’ fruit, as found in pre-
vious studies on these cultivars (Eccher Zerbini et al., 
2003, 2005; Rizzolo et al., 2005, 2008; Vanoli et al., 2008, 
2010  a) and on other pear cultivars (Watkins, 2006 and 
references herein). Control ‘Abbé Fétel’ pears produced 
more ethylene than control ‘Conference’ pears and were 
less sensitive to 1-MCP treatment, as shown mainly by the 
sensory analysis results and, secondly, by quality param-
eters, as found by Eccher Zerbini et al. (2003, 2005).

Control fruit from both cultivars with shelf life under-
went skin yellowing and pulp softening. However, control 
‘Abbé Fétel’ pears already upon removal after 21 weeks 
storage in CA soften to firmness values lower than 40 N, 
the threshold value corresponding to edible-firm texture 
for this cultivar (Predieri and Gatti, 2009). ‘Conference’ 
control fruit softened rapidly with shelf life, reaching the 
minimal level of acceptable eating quality of 10 N (Chiri-
boga et al., 2013) already after 5 days of shelf life at 20°C. 
Fruit softening in control pears was similar to that found 
in previous experiments on CA and DCA ‘Abbé Fétel’ 
fruit stored at -0.5°C (Rizzolo et al., 2014; Vanoli et al., 
2015) and on ‘Conference’ fruit stored in NA and CA 
at -1°C (Folchi and Bertolini, 2008) and in air at -0.5°C 
(Chiriboga et al., 2013). The treatment with 1-MCP at 

the concentration of 300 nL L–1 prevented ripening dur-
ing the 7-day shelf life at 20°C, even if slight decreases in 
firmness, stiffness and energy-to rupture were found for 
1-MCP treated ‘Abbé Fétel’ pears; these slight changes, 
indeed, influenced the sensory firmness and juiciness. In 
contrast, in 1-MCP treated ‘Conference’ pears, only stiff-
ness slightly decreased with shelf life, and no changes in 
the sensory profile were found with storage time and shelf 
life. On the contrary, Folchi and Bertolini (2008) observed 
that in ‘Conference’ pears harvested at 64.7 N and treated 
with 300 nL L–1 1-MCP, stored at -1°C up to four months 
there was a slight softening of 6 N, followed by a further 
softening to 40 N, prolonging storage up to seven months 
plus seven days of shelf life at 20°C. This difference could 
be due to the fact that ‘Conference’ pears had been har-
vested at a less advanced stage of maturity as assessed by 
the firmness value of 71 N and hue value of 108°, which 
are similar to the values reported by Chiriboga et al. 
(2013) for early and mid harvests. These authors reported 
that in two years ‘Conference’ pears harvested before or 
around the commercial harvest date remained firm after 
treatment with 1-MCP and lost their ability to soften even 
after several days at 20°C. In contrast 1-MCP applied at 
more advanced stages of maturity slowed down the soften-
ing process without completely blocking it.

5. Conclusions

The 1-MCP treatment at harvest influenced the physi-
ological and quality changes of ‘Conference’ and ‘Abbé 
Fétel’ pears stored in CA after ILOS periods. 1-MCP 
dramatically decreased the concentrations of α-farnesene 
and CTols in the fruit skin at the end of the ILOS period 
both in ‘Conference’ and ‘Abbé Fétel’ pears, and affected 
the concentrations of fermentative metabolites in the fruit 
pulp, lowering, after the ILOS period, the ethanol concen-
tration in both cultivars and the ethyl acetate amount in 
‘Abbé Fétel’ pears. The 1-MCP treatment drastically re-
duced the ethylene production during shelf life, impaired 
fruit softening to edible texture, and delayed fruit yellow-
ing both during storage and shelf life. Upon sensory tast-
ing, 1-MCP treated fruit was firmer and less juicy, sweet 
and aromatic than control fruit, without any changes with 
shelf life in ‘Conference’ fruit and with a slight decrease 
in sensory firmness and juiciness in ‘Abbé Fétel’ pears. It 
was confirmed that 1-MCP prevents superficial scald in 
both cultivars, and soft scald in ‘Abbé Fétel’ pears, where-
as in ‘Conference’ fruit it either has no effect or enhances 
the incidence and severity of blackening, a disorder which 
may not be dependent on oxidation products in the skin. 

Acknowledgements

Research carried out within the project “Effects of 
1-MCP application on ‘Abbé Fétel’ and ‘Conference’ 



95

Vanoli et al., ‘Conference’ and ‘Abbé Fétel’ pears treated with 1-methylcyclopropene

pears stored in different low oxygen atmospheres” was 
funded by AgroFresh Europe.

References

ARGENTA L.C., MATTHEIS J.P., FAN X., FINGER F.L., 2004 
- Production of volatile compounds by Fuji apples following 
exposure to high CO

2
 or low O

2
. - J. Agric. Food Chem., 52: 

5957-5963.
BAI J., PRANGE R.K., TOIVONEN P.M.A., 2009 - Pome 

Fruits, pp. 267-286. - In: YAHIA E.M. (ed.) Modified and 
controlled atmospheres for the storage, transportation, and 
packaging of horticultural commodities. CRC Press, Boca 
Raton, FL, USA, pp. 608.

BAIN J.M., MERCER F.J., 1963 - The submicroscopic cytology 
of superficial scald, a physiological disease of apples. - Aust. 
J. Biol. Sci., 16: 442-449.

BERTOLINI P., BOTTARDI S., DALLA ROSA M., FOLCHI 
A., 1997 - Effect of controlled atmosphere storage on the 
physiological disorders and quality of ‘Conference’ pears. - 
Ital. J. Food Sci., 4: 303-312.

BERTOLINI P., GUIZZARDI M., CASADEI C., 2002 - Influ-
ence of calcium and of oxygen levels on soft scald of stored 
‘Abbè Fètel’ pears. - Acta Horticulturae, 596: 851-856.

BIANCHI G., ECCHER ZERBINI P., RIZZOLO A., 2009 - 
Short-term training and assessment for performance of a 
sensory descriptive panel for the olfactometric analysis of 
aroma extracts. - J. Sensory Studies, 24(2): 149-165.

CALVO G., KUPFERMAN E., 2012 - Current DPA and ethoxy-
quin situation and alternatives to superficial scald control in 
apples and pears. - Acta Horticulturae, 945: 51-54.

CALVO G., SALVADOR M.E., SANCHEZ E., 2002 - Control 
of superficial scald in ‘Beurré d’Anjou’ pears with low oxy-
gen levels. - Acta Horticulturae, 596: 879-882.

CHIRIBOGA M.A., SCHOTSMANS W.C., LARRIGAUD-
IÈRE C., DUPILLE E., RECASENS I., 2013 - Responsive-
ness of ‘Conference’ pears to 1-methylcyclopropene: the role 
of harvest date, orchard location and year. - J. Sci. Food 
Agric., 93(3): 619-625.

CONERPO, 2010 - Report Prognosfruit 2010. - Kyiv, 5−6 Au-
gust, 2010, http://www.prognosfruit.eu.

DU Z., BRAMLAGE W.J., 1993 - A modified hypothesis in the 
role of conjugated trienes in superficial scald development 
on stored apples. - J. Am. Soc. Hortic. Sci., 118: 807-813.

ECCHER ZERBINI P., CAMBIAGHI P., GRASSI M., RIZZO-
LO A., 2003 - Effect of 1-MCP on the quality of pears during 
storage, pp. 290-293. - In: VENDRELL M., H. KLEE, J.C. 
PECH, and F. ROMOJARO (eds). Biology and Biotechnol-
ogy of the Plant Hormone Ethylene III. IOS Press, Amster-
dam, The Netherlands, pp. 471.

ECCHER ZERBINI P., CAMBIAGHI P., GRASSI M., RIZZO-
LO A., 2005 - The effect of 1-MCP on the quality of ‘Con-
ference’ and ‘Abbé Fétel’ pears. - Acta Horticulturae, 671: 
397-403.

FELLMAN J.K., MATTINSON D.S., BOSTICK B.C., 
METTHEIS J.P., PATTERSON M.E., 1993 - Ester biosyn-
thesis in “Rome” apples subjected to low-oxygen atmo-
spheres. - Postharvest Biol, Technol., 3: 201-214.

FOLCHI A., BERTOLINI P., 2008 - Prevenzione del riscaldo 
superficiale delle pere Conference mediante basso ossigeno 
e 1-MCP. - Italus Hortus, 15(6): 91-98.

GAPPER N.E., BAI J., WHITAKER B.D., 2006 - Inhibition of 
ethylene-induced α-farnesene synthase gene PcAFS1 ex-
pression in ‘d’Anjou’ pears with 1-MCP reduces synthesis 
and oxidation of α-farnesene and delays development of su-
perficial scald. - Postharvest Biol. Technol., 41: 225-233.

HUELIN F.E., COGGIOLA I.M., 1970 - Superficial scald, 
a functional disorder of stored apples: V. Oxidation of α-
farnesene and its inhibition by diphenylamine. - J. Sci. Food 
Agric., 21: 44-48.

ISIDORO N., ALMEIDA D.P.F., 2006 - α-Farnesene, conjugat-
ed trienols, and superficial scald in ‘Rocha’ pear as affected 
by 1-methylcyclopropene and diphenylamine. - Postharvest 
Biol. Technol., 42: 49-56.

LEE S.P., CHEN P.M., CHEN T.H.H., VARGA D.M., MIELKE 
E.A., 1990 - Differences in biochemical components between 
the skin tissues of normal and black-speckled ‘d’Anjou’ 
pears after prolonged low-oxygen storage. - J. Amer. Soc. 
Hort. Sci., 115(5): 784-788.

LO SCALZO R., ECCHER ZERBINI P., GRASSI M., 2002 - 
Composition of hexane extracts from ‘Conference’ pear peel. 
- Acta Horticulturae, 596: 867-870.

LUMPKIN C., FELLMAN J.K., RUDELL D.R., MATTHEIS 
J., 2014 - “Scarlett Spur Red Delicious” apple volatile pro-
duction accompanying physiological disorder development 
during low pO

2
 controlled atmosphere storage. - J. Agric. 

Food Chem., 62: 1741-1754.
LURIE S., LERS A., SHACHAM Z., SONEGO L., BURD S., 

WHITAKER B., 2005 - Expression of α-farnesene synthase 
AFS1 and 3-hydroxy-3-methylglutaryl coenzyme A reduc-
tase HMG2 and HMG3 in relation to α-farnesene and con-
jugated trienols in ‘Granny Smith’ apples heat or 1-MCP 
treated to prevent superficial scald. - J. Am. Soc. Hort. Sci., 
130: 232-236.

LURIE S., WATKINS C. B., 2012 - Superficial scald, its etiol-
ogy and control. - Postharvest Biol. Technol., 65: 44-60.

MATTHEIS J., FELICETTI D., RUDELL D.R., 2013 - Pithy 
brown core in ‘d’Anjou’ pear (Pyrus communis L.) fruit de-
veloping during controlled atmosphere storage at pO

2
 deter-

mined by monitoring chlorophyll fluorescence. - Postharvest 
Biol. Technol., 86: 259-264.

MATTHEIS J.P., BUCHANAN D.A., FELLMAN J.K., 1991 - 
Change in apple fruit volatiles after storage in atmospheres 
inducing anaerobic metabolism. - J. Agric. Food Chem., 39: 
1602-1605.

MATTHEIS J.P., RUDELL D., 2011 - Responses of ‘d’Anjou’ 
pears (Pyrus communis L.) fruit to storage at low oxygen 
setpoints determined by monitoring fruit chlorophyll fluores-
cence. - Postharvest Biol. Technol., 60: 125-129.

PECHOUS S.W., WATKINS C.B., WHITAKER B.D., 2005 - 
Expression of α-farnesene synthase gene AFS1 in relation to 
levels of α-farnesene and conjugated trienols in peel tissue 
of scald-susceptible ‘Law Rome’ and scald-resistant ‘Idared’ 
apple fruit. - Postharvest Biol. Technol., 35: 125-132.

PRANGE R.K., DeLONG J.M., WRIGHT A.H., 2011 - Stor-
age of pears using dynamic controlled-atmosphere (DCA), 
a non-chemical method. - Acta Horticulturae, 909: 707-717.



96

Adv. Hort. Sci., 2015 29(2-3): 84-96

PREDIERI S., GATTI M., 2009 - Effects of cold storage and shelf 
life on sensory quality and consumer acceptance of ‘Abate Fe-
tel’ pears. - Postharvest Biol. Technol., 51: 342-348.

RIZZOLO A., BIANCHI G., GRASSI M., VANOLI M., 2015 - 
Alpha-farnesene, conjugated trienols, fermentative metabo-
lites and superficial scald in ‘Conference’ pears as affected by 
1-methylcyclopropene, initial low oxygen stress and controlled 
atmosphere storage. - Acta Horticulturae, 1071: 429-436.

RIZZOLO A., CAMBIAGHI P., GRASSI M., ECCHER 
ZERBINI P., 2005 - Influence of 1-methylcyclopropene and 
storage atmosphere on changes in volatile compounds and 
fruit quality of Conference pears. - J. Agric. Food Chem., 
53: 9781-9789.

RIZZOLO A., GRASSI M., VANOLI M., 2010 - La conservazi-
one delle pere in AC dinamica: scambi gassosi e incidenza 
delle fisiopatie. - Frutticoltura, 72(10): 38-44.

RIZZOLO A., GRASSI M., VANOLI M., 2014 - 1-Methylcyclo-
propene application, storage temperature and atmosphere 
modulate sensory quality changes in shelf-life of ‘Abbé Fétel’ 
pears. - Postharvest Biol. Technol., 92: 87-97.

RIZZOLO A., VANOLI M., GRASSI M., ECCHER ZERBINI 
P., 2008 - Gas exchanges in 1-methylcyclopropene treated 
‘Abbé Fétel’ pears during storage in different atmospheres. - 
Acta Horticulturae, 796: 143-146.

TSANTILI E., GAPPER N.E., ARQUIZA J.M.R.A., WHITAK-
ER B.D., WATKINS C.B., 2007 - Ethylene and α-farnesene 
metabolism in green and red skin of three apple cultivars 
in response to 1-methlcyclopropene (1-MCP) treatment. - J. 
Agric. Food Chem., 55: 5267-5276

VANOLI M., ECCHER ZERBINI P., GRASSI M., RIZZOLO A., 
2010 a - Ethylene production and quality in 1-methylcyclo-
propene treated Abbé Fétel pears after storage in dynamically 
controlled atmosphere. - Acta Horticulturae, 876: 31-38.

VANOLI M., GRASSI M., ECCHER ZERBINI P., RIZZOLO 
A., 2010 b - Fluorescence, conjugated trienes, α-farnesene 
and storage disorders in ‘Abbé Fétel’ pears cooled with dif-
ferent speeds and treated with 1-MCP. - Acta Horticulturae, 
858: 191-197.

VANOLI M., RIZZOLO A., GRASSI M., 2015 - Fruit quality 
and sensory characteristics of 1-MCP treated ‘Abbé Fétel’ 
pears after storage under dynamic controlled atmosphere at 
different temperatures. - Acta Horticulturae, 1071: 437-445.

VANOLI M., RIZZOLO A., GRASSI M., ECCHER ZERBI-
NI P., 2008 - Storage disorders and quality in ‘Abbé Fétel’ 
pears treated with 1-methylcyclopropene. - Proceedings In-

ternational Congress: “Novel approaches for the control of 
postharvest diseases and disorders”. Bologna, Italy, 3-5 May 
2007, pp. 269-277.

VILLALOBOS-ACUÑA M.G., BIASI W.V., FLORES S., JI-
ANG C.-Z., REID M.S., WILLITS N.H., MITCHAM E.J., 
2011 a - Effect of maturity and cold storage on ethylene bio-
synthesis and ripening in ‘Bartlett’ pears treated after har-
vest with 1-MCP. - Postharvest Biol. Technol., 59: 1-9.

VILLALOBOS-ACUÑA M.G., BIASI W.V., MITCHAM E.J., 
HOLCROFT D., 2011 b - Fruit temperature and ethylene 
modulate 1-MCP response in ‘Bartlett’ pears. - Postharvest 
Biol. Technol., 60: 17-23.

WANG Z., DILLEY D.R., 2000 - Initial low oxygen stress con-
trols superficial scald of apples. - Postharvest Biol. Technol., 
18: 201-213.

WATKINS, C.B., 2006 - The use of 1-methylcyclopropene (1-
MCP) on fruits and vegetables. -Biotechnology Advances, 
24: 389-409.

WHITAKER B.D., 2007 - Oxidation products of α-farnesene 
associated with superficial scald development in d’Anjou 
pear fruits are conjugated trienols. - J Agric. Food Chem., 
55: 3708-3712.

WHITAKER B.D., 2013 - Genetic and biochemical bases of 
superficial scald storage disorder in apple and pear fruits. - 
Acta Horticulturae, 989: 47-60.

WHITAKER B.D., SCHMIDT W.F., KIRK M.C., BARNES 
S., 2001 - Novel fatty acid esters of p-coumaryl alcohol in 
epicuticular wax of apple fruit. - J. Agric. Food Chem., 49: 
3787-3792.

WRIGHT H.A., DeLONG J.M., GUNAWARDENA A.H.L.A.N., 
PRANGE R.K., 2012 - Dynamic controlled atmosphere 
(DCA): Does fluorescence reflect physiology in storage? - 
Postharvest Biol. Technol., 64: 19-30.

ZERBINI E.P., GRASSI, M., 2010 - Chlorophyll fluorescence 
and gas exchanges in ‘Abbé Fétel’ and ‘Conference’ pears 
stored in atmosphere dynamically controlled with the aid of 
fluorescence sensors. - Acta Horticulturae, 857: 469-474.

ZOFFOLI J.P., 1994. - Pear fruit scald: a physiologic disorder 
involving α-farnesene, conjugated trienes and α-tocopherol. 
- Master of Science Thesis at Oregon State University, Or-
egon, USA.

ZOFFOLI J.P., RICHARDSON D., CHEN P., SUGAR D., 1998 
- Spectrophotometric characterization of superficial and se-
nescent scald in pear fruits relative to different stages of ma-
turity. - Acta Horticulturae, 475: 543-558.