EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Post‐harvest treatment of cherries; a brief review
Oliver Doubleday
Aerobic Respiration
Vital Heat
C6H12O6 + 6O2
6CO2 + 6H20
Krebs Cycle
Reaction with oxygen generates “Vital Heat” and produces CO2 (and water)
Vital Heat can be calculated from rate of production of CO2
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Rates of Cherry Respiration
Temperature (oC)
0
5
10 20
ml CO2/kg/hr 3‐5 5‐9 15‐17 22‐28
oC increase/day 0.49 0.9 2.0 3.0
From UC Davis Post Harvest Technology Centre
Aerobic Respiration
C6H12O6 + 6O2
C6H12O6 + 6O
2
6CO2 + 6H20
6CO2 + 6H20
Classic Controlled Atmosphere Storage
Low O2 inhibits respiration (starve reaction)
High CO2 inhibits respiration (“end product inhibition”)
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Anaerobic Respiration (fermentation)
C6H12O6
2C2H5OH + 2CO2
No oxygen
Good example of ‘end product inhibition’
Fermentation products have taints. Avoid.
Respiration
• Must cool fruit ‐ if not gets hotter
‐ avoid depleting substrate (burning quality)
• Can slow respiration by reducing oxygen and accumulating carbon dioxide
• Must avoid very low oxygen conditions that will give rise to anaerobic respiration and taste taints (genetic variation in peoples’ ability to detect?).
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Maintain Humidity
Weight Loss of Cherry Stalks at 20oC
100.0
90.0
80.0
70.0
%
60.0
50.0
40.0
30.0
20.0
10.0
0.0
Series1
T0
1 hour
2 hours
3 hours
4 hours
5 hours
100.0
96.2
92.3
89.2
83.3
80.4
Air Blast Chilling
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Air Blast Chilling
3/
4
‐ 7/8 cooling c 2 hrs in well perforated and ventilated crates, 5 kg fruit in 60x40x15 cm. Note effects of sub‐optimal air flow, including shielding. Consider implications of packaging on airflow.
Hydro‐cooling
24 x faster than air
Must have adequate water flow for stacks of trays
Water can crack fruit – minimise duration
Water must be clean (chlorine or chlorine dioxide treatment). Scope for treatment with CRAS compounds
• Must avoid impact damage: fruit drops <10cms, water droplets <15 cms (put mesh over top of trays)
•
•
•
•
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Hydro‐cooling
250 ml water flow. Top and bottom of stack 10 high.
0.88 heat remaining after 15 seconds
1000 ml water flow. Top and bottom of stack 10 high.
0.88 heat remaining after 15 seconds
Temperature, firmness, bruising
• Warm fruit is softer (hence avoid harvest during very hot conditions – start earlier!)
• Chilled fruit is more susceptible to bruising and pitting.
• Avoid handling fruit below 10oC
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Good Storage: 1
Manage temperature, avoid hot. What target temperature? Avoid <10oC if handling, else 0oC. Maintain humidity; water loss = wrinkled skin, shrivelled pedicle, weight loss. Modified Atmosphere Packaging crates (Janny), shrouds (SDA Packaging Ltd, Amcor), bags (Amcor) have high humidity, low O2 and high CO2 which can reduce fungal infections (elsewhere approved use of Rovoral). Good Storage: 2
Optimum O2 3‐10%, CO2 10‐15% (UC Davis Postharvest Technology Centre). Must measure gases. Avoid very low O2 (taints from fermentation). High CO2 discolours and also taints
Consider effects of sealing warm fruit (c. 10oC), difficult to subsequently cool.
Disruptions to refrigeration all more acute with ‘stringent’ bags (lowest possible O2 highest CO2). Majority of global experience is of fruit stored during sea freight. In China cool chain disruption at the end of journey is very common
Equilibrate fruits’ O2 & CO2 in air prior to warming after MA storage.
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Criteria for judging when to pick
•
•
•
•
•
•
Size (also weight)
Brix (refractometer, % sugar)
Colour (CTIFL 1‐7 scale)
Firmness (Durofil or Firmtech)
Acidity (% malic acid, titrated to pH 8.2)
Strig retention (severance force). Useful independent measure of ripeness. Also important not to lose pedicle during storage (varietal differences, e.g. Kordia weak, Penny strong)
Sampling technique, confidence limits (50 fruit sample)
Size mm
120%
100%
80%
60%
40%
20%
0%
22
23
24
25
26
27
28
29
30
31
32
Actual
100%
100%
100%
100%
96%
88%
84%
72%
48%
18%
10%
95% C
100%
100%
100%
100%
88%
78%
74%
61%
37%
11%
5%
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Giorgia Size mm
Giorgia size mm
50
45
40
35
30
%
25
20
15
10
5
0
30 June
15 July
28 July
24
25
26
27
28
29
30
31
32
0
4
2
20
18
44
10
2
0
33
34
0
10
8
36
26
14
0
8
12
28
30
2
2
2
12
10
0
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Giorgia Colour ‐ CTILF
100
90
80
70
60
%
50
40
30
20
10
0
30 June
1
2
3
4
5
4
4
28
38
22
6
15 July
7
4
0
56
44
28 July
100
Giorgia Brix
35
30
25
20
%
15
10
5
0
12
13
14
15
16
17
18
19
20
21
22
4
4
10
18
30
14
8
6
4
2
0
15 July
0
2
2
10
18
30
20
8
6
2
2
0
28 July
0
2
2
0
18
6
20
18
10
12
6
6
30 June
23
24
25
26
27
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Giorgia – Fruit Firmness (Firmtech)
450
400
350
300
250
200
150
100
50
0
Series1
30 June
15 July
28 July
379
396
345
Giorgia fruit weight gm
12
11
10
9
Grams
8
7
6
5
Series1
30 June
15 July
28 July
9.8
11.2
11.6
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Taste
• Sweet (sugar)
• Sour (acid)
• Salt
• Bitter • Umami (glutamate)
The balance of sugar & acid is critical. Cherries have relatively low levels of flavour compounds (cf smell cherry vs strawberry). Taste is king.
Taste ‐ Krebs or Citric Acid Cycle
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Sugar and Acid
• Sugar 14‐25% . Many varieties unripe below 16%.
• Acid from 0.50% (late stored or over‐ripe fruit) to 1.20% (unripe).
• Sugar concentration is 15‐55 x greater than malic acid. 20 x for excellent, fresh, ripe fruit; 40 x for late stored fruit
• As acidity is preferentially lost through the Krebs Cycle the proportion of these elements, the two major components of taste in cherries, changes
Giorgia Brix & Acidity
30.00
1.20
25.00
1.00
20.00
0.80
% Acid
% Brix
15.00
0.60
10.00
0.40
5.00
0.20
0.00
30 June
15 July
28 July
Brix
16.63
21.91
24.00
Acid
1.04
1.01
0.82
0.00
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Giorgia: Sugar & Acid mg per fruit
3000
120
2500
100
2000
80
Sugar 1500
60
1000
40
500
20
0
30 June
15 July
28 July
Sugar mg
1630
2454
2784
Acid mg
102
113
95
Acid
0
Giorgia: Acid as % of Brix
7.00%
6.00%
5.00%
Acid as % of Brix
4.00%
3.00%
2.00%
1.00%
0.00%
Acid as % Brix
30 June
15 July
28 July
6.25%
4.59%
3.43%
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Ripening of Kordia
35.0
400
30.0
350
300
25.0
Size Weight
Brix
250
20.0
200
Firmness
15.0
150
10.0
100
5.0
50
0.0
Size
2
july
6
july
11
July
21
july
25.7
26.9
28.2
28.9
Weight 8.5
9.7
10.6
11.9
Brix
17.8
19.2
20.7
21.5
Firm
379
361
339
314
0
Kordia: Sugar & Acid mg per fruit
3000
120
2500
100
2000
80
Malic mg
Sugar mg
1500
60
1000
40
500
20
0
2
july
6
july
Sugar/Fruit 166
172
208
261
Acid/Fruit
96
108
100
99
11
july
21
july
0
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Kordia: Acid as % of Brix
7.00%
6.00%
5.00%
4.00%
3.00%
2.00%
1.00%
0.00%
2 july
6 july
11
july
21
july
Series1 5.94%
5.58%
5.18%
3.81%
Factors affecting storage
•
•
•
•
•
•
•
•
•
•
Variety – some better than others
Timing of pick
Age of cropping wood
Crop load (excessive load retards harvest & softens fruit, reduces quality)
Rootstocks (although principal effects of rootstock are on flowering time and precocity) Soil moisture deficit Nutrition, including fertigation and foliar feeds
Gibberellic Acid Relative humidity, covers
Sunlight
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Brix & Acidity in MAP stored Kordia
1.20
25.0
1.00
20.0
0.80
% Acid
15.0
0.60
% Brix
10.0
0.40
5.0
0.20
0.0
Week 0
1
2
3
4
5
6
7
8
Brix
21.8
21.9
22.0
21.2
Acid
0.96
0.80
0.71
0.60
0.00
Acid as % Sugar in MAP Stored Kordia
5.00
4.50
4.00
3.50
3.00
2.50
Acid as % 2.00
Sugar
1.50
1.00
0.50
0.00
Acid as %Sugar
Week 0
4.39
1
2
3.66
3
4
5
6
3.22
7
8
2.85
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Resume
• When to pick? characteristics to monitor under your husbandry conditions.
• Importance of rapid chilling. Air & Water chilling. Relationship between temperature, firmness & bruising. Don’t handle >10oC. Humidity. Shielding & packaging and flow rates for cooling
• Correct atmosphere ‐ low O2 high CO2 avoid fermentation taints
• Role of acidity in taste
• Preferential loss of acidity during ripening & storage (especially over‐ripe fruit).
Ctifl Acidity
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EMR Association & AHDB Horticulture Tree Fruit Day 23.02.16
Ctifl Firmness
Ctifl Sugar
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