Washington Tree Fruit Research Commission

Research Reports

Postharvest Physiology of Winter Pears (Funded by WPCC) (2003)

FINAL PROJECT REPORT
WTFRC Project #
YEAR 0/0
Organization Project #
Title:Postharvest Physiology of Winter Pears (Funded by WPCC)
PI:Paul M. Chen
Organization:
 PDF version of report

Collaborators

J. P. Mattheis; R. A. Spotts; S. R. Drake

Objectives

1.       To extend the marketability of ‘d’Anjou’ pears by combination of MCP and ethylene treatment.
2.       To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and superficial scald disorder of  ‘d’Anjou’ pears after air storage.
3.       To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and internal breakdown disorder of  ‘Bartlett’ pears after air storage.
4.       To develop innovative procedures for freeze-drying fruit bits of ‘d’Anjou’ Pears as “value-added” commodities.

 

Significant findings

1.       To extend the marketability of ‘d’Anjou’ pears by combination of MCP and ethylene treatment.
            We find that conditioning ‘d’Anjou’ pears in air enriched with 100 ppm ethylene at 20°C for 3 or 4 days followed by the treatment with 1 ppm MCP at 20°C for 24 hours could extend the shelf-life of “ready-to-eat” ‘d’Anjou’ fruit for up to 14 days at 20°C.  Therefore, 1ppm-MCP treatment provides a powerful tool for extending the marketability of partially ripened ‘d’Anjou’ pears.
2.       To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and superficial scald disorder of  ‘d’Anjou’ pears after air storage.
We find that pre-storage treatment of 'd'Anjou' pears with 10 to 20 ppb MCP did not inhibit normal ripening process but inhibited the development of superficial scald disorder.  It is concluded that pre-storage treatment of 'd'Anjou' pears with 10 to 20 ppb MCP could be used as an alternative method of scald control measure of ‘d’Anjou’ pears. 
 
3.       To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and internal breakdown disorder of  ‘Bartlett’ pears after air storage.
            We find that pre-storage treatment of ‘Bartlett’ pears with 50 ppb MCP extended storage life in air at -1°C for 4 months and 50ppb-MCP-treated fruit ripened with juicy texture without developing any internal breakdown disorder.  It is concluded that pre-storage treatment of ‘Bartlett’ pears with 50 ppb MCP can extend the storage life of ‘Bartlett’ pears without inhibiting normal ripening process.

4.       To develop innovative procedures for freeze-drying fruit bits of ‘d’Anjou’ Pears as “value-added” commodities.
     We find the ripe ‘d’Anjou’ pear slices can be vacuum-infiltrated with soluble-solids solution; subjected to “individually quick freezing” (IQF) process; and then freeze-dried.  We identified that one kind of soluble solids can increase the crisp texture of the freeze-dried pear slices.  This procedure may provide the pear industry with a potential to turn “Cull-grade” fruit into a profitable  “value-added” product.

Methods

Objective 1.  To extend the marketability of ‘d’Anjou’ pears by combination of MCP and ethylene treatment.
            ‘D’Anjou’ pears were harvested at commercial maturity with FF of 14.0 lb (±0.5 lb) on September 12, 2002.   Harvested fruits were transferred into 40-lb wooden boxes with polyethylene liner and stored in air at -1°C.  After 2 and 4 months of storage, fruits were conditioned in air enriched with 100 ppm ethylene at 20°C for 0 (no conditioning treatment), 1, 2, 3 and 4 days.  After conditioning treatment, fruit were treated with 1 ppm MCP at 20°C for 24 hours.  MCP-treated fruit were then held in air at 20°C.  Changes in flesh firmness (FF) were determined daily for 7 days.
Objective 2.  To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and superficial scald disorder of  ‘d’Anjou’ pears after air storage.          
'D'Anjou' pears were harvested at commercial maturity with flesh firmness (FF) of 14 lb (±1.0 lb) and held in air at -1°C for 5 days.  When the core temperature of fruit reached -1°C, fruit were treated with different dosages of MCP at 20°C for 24 hours.  The dosages of MCP were: 0 (Control), 10, 20, 30, 50, 70 and 100 ppb.  Treated fruit were stored in air at -1°C for 3, 4, and 5 months.   After each storage interval, fruit were held 20°C in a ripening room enriched with 100ppm ethylene (±20 ppm) for 14 days.  Changes in flesh firmness (FF), extractable juice (EJ), titratable acids (TA), and soluble solids (SS) were determined on day 1, 7 and 14 of ripening.  Incidences of superficial scald disorder were assessed on day 7 and 14 of ripening.  Ethylene productions (EP) were determined daily for 15 days at 20°C
           
Objective 3.      To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and internal breakdown disorder of  ‘Bartlett’ pears after air storage. 
            ‘Bartlett’ pears harvested at optimum maturity (FF of 18 lbs) (H-1) and late maturity (FF of 16 lbs) (H-2) were treated with 50 ppb and 300 ppb MCP within 2 days after harvest.  Another group of untreated fruit for each harvest maturity were used as control.  Both control and MCP-treated fruits were stored in air at -1°C for 2, 4, and 6 months.  After each storage interval, both MCP-treated and control fruit were held at 20°C in air for 14 days.  Changes in flesh firmness (FF), extractable juice (EJ), titratable acids (TA) and soluble solids (SSC) were determined on day 1, 7 and 14 of ripening.  Incidences of internal breakdown (IB) disorder were assessed on days 7 and 14 of ripening.  Ethylene productions (EP) were determined daily for 15 days at 20°C.
 
Objective 4.  To develop innovative procedures for freeze-drying fruit bits of ‘d’Anjou’ Pears as “value-added” commodities.
     ‘D’Anjou’ pears stored in either air or CA storage were ripened in at 20°C until flesh firmness (FF) softened to 6 lb.  Fruit were sliced into 16 sectors and then separately vacuum-infiltrated with three different kinds of soluble-solids solutions.  Treated fruit sectors were subjected to “individually quick freezing” (IQF) process and then freeze-dried.  Freeze-dried fruit sectors were organoleptically tasted for the crispness of its texture.

Results and discussion

Objective 1.  To extend the marketability of ‘d’Anjou’ pears by combination of MCP and ethylene treatment.
             Figure 1 shows the changes in flesh firmness (FF) of ‘d’Anjou’ pears during 4 days of ethylene conditioning after fruit had been stored in air at -1°C for 2 months.  Fruit conditioned for 0, 1, 2, 3 and 4 days softened to flesh firmness of 14, 13.5, 10.5, 9 and 6 lb respectively.  After 24 hrs of MCP treatment at 20°C, fruit softened further and decreased by about 1 lb for each conditioned category.  MCP-treatment of ethylene-conditioned fruit slowed down the softening process on the shelf life at 20°C (Fig. 1).  Fruit conditioned for 3 and 4 days followed by 1ppm MCP treatment softened to no less than 3 lb on day 7 after MCP treatment (Fig. 1).  We find that conditioning ‘d’Anjou’ pears in air enriched with 100ppm ethylene at 20°C for 3 or 4 days could reach the state of “ready-to-eat” ripeness in the retail markets.  Treatment of  “ready-to-eat” ‘d’Anjou’ fruit with 1 ppm MCP at 20°C for 24 hours could extend the shelf-life for up to 14 days at 20°C.  Therefore, 1ppm-MCP treatment provides a powerful tool for extending the marketability of partially ripened ‘d’Anjou’ pears.
           We continue to investigate 1ppm-MCP treatment of partially ripened ‘d’Anjou’ pears when they have been stored in air for 4 months and in CA for 6 months.  The results will be presented in the next annual report.
Fig. 1.  Fruit softening patterns of ‘d’Anjou’ pears after 0, 1, 2, 3 and 4 days of ethylene conditioning at 20°C and during 7 days of holding on the shelf at 20°C after 1ppm MCP treatment.  ‘D’Anjou’ fruit had been stored in air at -1°C for 2 months and then conditioned in a ripening room enriched with 100ppm ethylene for 1, 2, 3 and 4 days at 20°C followed by 1ppm MCP treatment at 20°C for 24 hour.






 

 
Objective 2.  To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and superficial scald disorder of  ‘d’Anjou’ pears after air storage.             
After 3 months of storage, ‘d’Anjou’ fruit treated with 30, 50, 70 and 100 ppb MCP were incapable of softening to the proper ripeness but did not develop any incidence of superficial scald disorder after 7 days at 20°C (Fig. 2, A & B).  Fruit treated with 10 and 20 ppb MCP ripened normally and softened to FF of 3-4 lb after 7 days at 20°C (Fig. 2, A).  Fruit treated with 10 ppb MCP developed minor incidence of superficial scald disorder on day 7 at 20°C while those treated with 20 ppb MCP were completely free from superficial scald disorder (Fig. 2, B).  Control fruit reached the proper ripeness with FF of 2.5 lb on day 7 at 20°C (Fig. 2, A).  Ripened control fruit developed very high incidence of superficial scald disorder on day 7 at 20°C (Fig. 2, B).  The results indicated that MCP dosage of 10 and 20 ppb could effectively control superficial scald disorder without inhibiting ripening process of ‘d’Anjou’ pears after 3 months of air storage.
We continue to investigate MCP-treated ‘d’Anjou’ pears after 4 and 5 months of air storage.  The results will be presented in the next annual report.
Fig. 2.  Changes in flesh firmness (FF) (A) and incidence of superficial scald disorder (B) of ‘d’Anjou’ pears after 3 months of air storage at -1°C plus 7 days of ripening at 20°C.  Fruit had been treated with different concentrations of MCP within 14 days of storage after harvest.

 

Objective 3.    To investigate the dosage effect of MCP treatment on inhibiting ripening capacity and internal breakdown disorder of  ‘Bartlett’ pears after air storage. 
            Regardless of harvest maturity, ‘Bartlett’ pears treated with 300 ppb MCP did not ripen normally and softened to 5.9 lb or firmer during 14 days at 20°C after 2 or 4 months of storage (Tables 1-4).  After 2 months of storage, fruit treated with 50 ppb MCP did not ripen properly on day 7 at 20°C (Table 1 and 3).  After 4 months of storage, 50ppb-MCP-treated fruit ripened properly on day 7 at20°C regardless harvest maturity (Table 2 and 4).  MCP-(50 ppb)-treated fruit also ripened to proper flesh firmness of 2.5 lb and developed minimal incidence of internal breakdown (IB) disorder after 14 days at 20°C regardless of harvest maturity and storage length (Table 1-4).  Control fruit softened to below 0.5 lb and developed unacceptable incidence of IB disorder on day 7 or 14 of ripening after 4 months of storage regardless of harvest maturity (Table 2 and 4).  It was concluded that pre-storage treatment of 50 ppb MCP did not inhibit normal ripening of ‘Bartlett’ pears and extended the shelf life for 14 days in the retail markets.

Table 1.  Differences in flesh firmness (FF), extractable juice (EJ), soluble solids (SS), and titratable acids (TA) in optimum mature ‘Bartlett’ pears after 1, 7 and 14 days of ripening at 20 C.  ‘Bartlett’ pears had been treated with 300 ppb, 50 ppb, or 0 ppb (Control) MCP within 2 days after harvest (8-18-02) and stored in air at –1 C for 2 months.
Days at 20C
MCP (ppb)
FF
EJ
SS
TA
IB
1
300
18.8 ±0.2
70.5 ±0.5
12.6 ±0.1
5.5 ±0.4
0
50
15.7 ±0.2
66.8 ± 0.8
12.2 ±0.2
4.7 ±0.1
0
Control
14.7 ±0.3
65.2 ±0.8
12.1 ±0.1
4.7 ±0.2
0
7
300
13.0 ±0.9
64.7 ±0.3
12.4 ±0.2
4.8 ±0.1
0
50
8.5 ±0.6
56.3 ±1.5
12.6 ±0.3
4.5 ±0.1
0
Control
1.9 ±0.1
30.3 ±2.5
13.0 ±0.2
4.0 ±0.1
8.4
14
300
11.7 ±0.6
60.8 ±3.3
12.4 ±0.2
4.8 ±0.1
0
50
2.4 ±0.2
32.5 ±2.8
12.9 ±0.1
4.3 ±0.2
0
Control
0.7 ±0.1
44.0 ±3.6
12.5 ±0.1
3.8 ±0.4
100
Unit: FF (lb per square inch of force); EJ (ml juice per 100 g fresh weight pulp tissue); SS (%); TA (meq per 100 ml juice); IB (internal breakdown, %).
 

Table 2.  Differences in flesh firmness (FF), extractable juice (EJ), soluble solids (SS), and titratable acids (TA) in optimum mature ‘Bartlett’ pears after 1, 7 and 14 days of ripening at 20 C.  ‘Bartlett’ pears had been treated with 300 ppb, 50 ppb, or 0 ppb (Control) MCP within 2 days after harvest (8-18-02) and stored in air at –1 C for 4 months.
Days at 20C
MCP (ppb)
FF
EJ
SS
TA
IB
1
300
17.6 ±0.4
67.3 ±1.0
12.2 ±0.2
4.4 ±0.2
0
50
16.0 ±0.2
66.8 ± 0.8
12.2 ±0.2
4.1 ±0.1
0
Control
14.1 ±0.5
65.7 ±1.5
12.1 ±0.1
3.6 ±0.1
0
7
300
15.8 ±0.9
67.5 ±0.7
12.3 ±0.2
4.0 ±0.2
0
50
2.3 ±0.1
41.7 ±3.1
12.5 ±0.2
3.9 ±0.2
0
Control
1.2 ±0.1
44.0 ±4.6
12.5 ±0.2
3.6 ±0.1
94
14
300
10.6 ±0.3
54.0 ±3.6
12.5 ±0.1
3.7 ±0.1
0
50
1.6 ±0.1
40.0 ±4.0
12.4 ±0.2
3.4 ±0.1
11.6
Control
0.5 ±0.1
43.7 ±1.5
12.2 ±0.1
3.0 ±0.1
100
Unit: FF (lb per square inch of force); EJ (ml juice per 100 g fresh weight pulp tissue); SS (%); TA (meq per 100 ml juice); IB (internal breakdown, %).
Table 3.  Differences in flesh firmness (FF), extractable juice (EJ), soluble solids (SS), and titratable acids (TA) in late mature ‘Bartlett’ pears after 1, 7 and 14 days of ripening at 20 C.  ‘Bartlett’ pears had been treated with 300 ppb, 50 ppb, or 0 ppb (Control) MCP within 2 days after harvest (8-28-02) and stored in air at –1 C for 2 months.
Days at 20C
MCP (ppb)
FF
EJ
SS
TA
IB
1
300
14.8 ±0.2
68.0 ±1.0
12.9 ±0.4
4.8 ±0.3
0
50
14.0 ±0.6
68.3 ± 1.5
12.9 ±0.2
4.6 ±0.2
0
Control
13.8 ±0.3
65.6 ±2.1
13.2 ±0.2
4.4 ±0.1
0
7
300
12.6 ±0.2
66.8 ±0.3
13.0 ±0.1
4.7 ±0.4
0
50
6.7 ±0.2
51.8 ±5.1
13.4 ±0.3
4.5 ±0.1
0
Control
2.2 ±0.1
45.3 ±3.5
13.4 ±0.2
4.1 ±0.1
14.4
14
300
6.9 ±0.2
62.7 ±2.5
13.1 ±0.2
4.7 ±0.4
0
50
2.4 ±0.1
37.0 ±4.0
13.0 ±0.3
4.5 ±0.4
2.7
Control
0.3 ±0.0
50.0 ±2.0
12.4 ±0.2
3.1 ±0.1
100
Unit: FF (lb per square inch of force); EJ (ml juice per 100 g fresh weight pulp tissue); SS (%); TA (meq per 100 ml juice); IB (internal breakdown, %).

Table 4.  Differences in flesh firmness (FF), extractable juice (EJ), soluble solids (SS), and titratable acids (TA) in late mature ‘Bartlett’ pears after 1, 7 and 14 days of ripening at 20 C.  ‘Bartlett’ pears had been treated with 300 ppb, 50 ppb, or 0 ppb (Control) MCP within 2 days after harvest (8-28-02) and stored in air at –1 C for 4 months.
Days at 20C
MCP (ppb)
FF
EJ
SS
TA
IB
1
300
14.4 ±0.2
67.8 ±1.1
12.9 ±0.1
4.1 ±0.3
0
50
13.8 ±0.4
67.3 ± 1.5
13.0 ±0.2
3.6 ±0.2
0
Control
12.6 ±0.7
67.6 ±2.1
13.1 ±0.2
3.4 ±0.1
0
7
300
12.2 ±0.2
66.8 ±0.3
134 ±0.1
4.1 ±0.2
0
50
4.7 ±0.2
45.8 ±5.1
13.1 ±0.3
3.5 ±0.3
0
Control
1.2 ±0.1
38.3 ±3.5
13.2 ±0.2
3.1 ±0.2
100
14
300
5.9 ±0.5
55.7 ±2.8
13.3 ±0.2
3.6 ±0.4
0
50
1.5 ±0.3
45.4 ±3.5
13.0 ±0.2
3.3 ±0.4
25.1
Control
0.3 ±0.0
50.6 ±2.8
12.2 ±0.2
2.7 ±0.1
100
Unit: FF (lb per square inch of force); EJ (ml juice per 100 g fresh weight pulp tissue); SS (%); TA (meq per 100 ml juice); IB (internal breakdown, %).
Objective 4.  To develop innovative procedures for freeze-drying fruit bits of ‘d’Anjou’ Pears as “value-added” commodities.
     ‘D’Anjou’ pears stored in either air or CA storage were ripened in at 20°C until flesh firmness (FF) softened to 6 lb.  Fruit were sliced into 16 sectors and then separately vacuum-infiltrated with three different kinds of soluble-solids solutions.  Treated fruit sectors were subjected to “individually quick freezing” (IQF) process and then freeze-dried.  One kind of soluble solids was identified to increase the crisp texture of freeze-dried fruit sector.  This procedure may provide the pear industry with a potential to turn “Cull-grade” fruit into profitable “value-added” product.   

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