1

Mature Fruit Vegetables

Tomatoes

Peppers, Chiles

• Maturity at harvest critical for quality

• Chilling sensitive, but variable in sensitivity

• Ethylene can control ripening

• Moderate respiration rates; can be stored

Marita Cantwell, UC Davismicantwell@ucdavis.edu

Postharvest Technology Short Course June 2012Ch. 33 Postharvest Technology Book

Tomato Quality Attributes

• Size, shape• Condition

– no damage – no decay

• Texture– Firmness, mealiness,

juiciness, slice integrity• Color

– Red color and lycopene content

• Flavor and Composition– Sugars– Acids– Aroma volatiles– Vitamins

GREEN The tomato surface is completely green. The shade of green may vary from light to dark.

BREAKERS There is a definite break of color from green to bruised fruit Tannish-yellow, pink or red or 10% or less of the tomato surface.

TURNING Tannish-yellow, pink or red color shows on over 10% but not more than 30% of the tomato surface.

PINK Pink or red color shows on over 30% but not more than 90% of the tomato surface.

LIGHT RED Pinkish-red or red color shows on over 60% but red color covers not more than 90% of the tomato surface

1

2

3

4

5

6

Maturity & Ripening Stages

http://www.floridatomatoes.org/

RED Red means that more than 90% of the tomato surface, in aggregate, is red

http://www.tomato.org/

VR

Immature MG1 MG2 MG3 Br

Tomato mature-green & breaker stagesPROBLEMATIC!

Tomato photos: http://www.tomato.org/food/color.html

Time

Rel

ativ

e V

alu

e

Red colorYellow colorAromaFlavorSugarsSoluble pectinsPolymerized phenolics

Green colorAcidityStarchFlesh firmnessInsoluble pectinsSimple phenolics

Respiration

Ethylene

1 2 3 4 5 6

MG Breaker Turning Pink Light Red Red

µl C

O2/g

-h

0

10

20

30

Days at 20°C from Breaker stage

0 2 4 6 8 10 12 14 16 18

nl C

2H4/

g-h

0

1

2

3

4

5

6

7

8

9 Ethylene Production

Respiration T3

T5

T3rin

T3rin x T5

Ripening mutants retardthe ripening process

Example: Tomato rin mutant

2

Firmness Classes for Tomatoes

Firmness Class

Description

Firmness Newtons force to compress 5 mm

Very firm yields slightly to considerable finger pressure

30-50

Firm yields slightly to moderate finger pressure

20-30

Moderately firm -- 15-20

Moderately soft yields readily to moderate finger pressure

10-15

Soft yields to slight finger pressure 10

Very soft yields very readily to slight finger pressure

5

1 Newton = 9.81 kg-force or 4.45 pound-force

Other Textural CharacteristicsSlice IntegrityMealiness

Tomato Color

Carotenoids and other carotenes

Lycopene (90%)

Pigment extraction, Objective color values

Hue 95 78 62 48 40Lycopene 0.3 4.0 8.6 16.8 32.7

Lycopene in the pericarp, mg/kg FW

2 3 4 5 6

L* a* b* chroma hue

49.6 16.6 30.9 35.0 61.8

46.2 24.3 27.0 36.3 47.9

41.8 26.4 23.1 35.1 41.2

39.6 27.5 20.7 34.4 37.0

L* a* b* chroma hue

49.6 16.6 30.9 35.0 61.8

46.2 24.3 27.0 36.3 47.9

41.8 26.4 23.1 35.1 41.2

39.6 27.5 20.7 34.4 37.0

Typical ObjectiveColor Values for Tomatoes

Pink-Orange

Orange-Red

Red

Dark Red

ACIDSSUGARS

Low High

LowInsipid,

tastelessSweet

Moderate to High

Sour, tartBest flavor

combination

Soluble solids measured by a refractometer = sugars, but also organic acids, soluble pectins,

anthocyanins, phenolic compounds, ascorbic acid

Flavor and Sugar:Acid Ratio

We estimate flavor by measuring sugars (soluble solids) and

acids (titratable acidity)

Sugars (4-8%)

Acids (0.2-0.8%)

Aroma volatiles (ppm)

Tomato FlavorDepends on content of:

3

Tomato Type & Composition, U.S. Retail

Tomato Type

% Soluble Solids

% Titratable Acidity

Grape 7.55 0.62

Cherry 6.25 0.67

Orange Cluster 4.70 0.44

Round 4.65 0.33

Roma 4.25 0.31

Round Cluster 4.20 0.35Tomato Type

% Soluble Solids

% Titratable Acidity

Cherry 7.15 0.77

Campari 6.30 0.58

Romanita 6.30 0.44

Grape 5.60 0.51

Round greenhouse 4.50 0.36

Group 2

Group 1 Composition of Ripe Grape Tomato

Harvested at 3 Stages of Maturity

Initial

Maturity Stage

Weight fruit,

g

Red color, hue

Firmness, N force

Soluble solids,

%

Sugars

mg/mL

Titratable acidity,

%

Vitamin C

mg/100mL

3 4.9 36.8 11.5 5.9 27 0.59 96

4 5.7 36.3 13.6 6.7 30 0.68 97

5 5.9 37.7 13.7 7.5 33 0.67 99

LSD.05 0.6 ns 1.5 0.8 3 0.09 ns

Average 7 cvs, Cantwell, 2003

3 4 5

Minimum harvest stage should be Stage 4 (pink-orange)

Checker boarding

Should never be aproblem with vine ripe tomatoes!

At Packhouse

At Distribution

Quality of ripe greenhouse TOV tomatoes of two cultivars. Fruit were stored at 12.5C for 14days. Fruit are numbered from 1 to 5 in order of ripening. Only trusses with all red fruit after 14 days were evaluated (Cantwell, 2010).

Cultivar Fruit no

Weightg

Color (hue)

FirmnessN

Soluble solids

%

Titratable acidity

%

Espedella 1 174.1 40.3 18.1 3.9 0.38

2 153.0 38.9 15.8 4.0 0.39

3 151.6 39.8 22.1 3.9 0.43

4 143.9 39.1 23.0 3.9 0.43

5 136.3 40.0 30.3 3.8 0.47

Success 1 143.9 37.0 12.7 3.6 0.30

2 131.7 37.2 12.1 3.6 0.30

3 136.3 36.7 16.3 3.5 0.31

4 130.0 37.3 16.9 3.6 0.35

5 125.1 37.3 18.2 3.5 0.36

LSD.05 5.2 1.8 2.7 0.5 0.05

Storage of Tomatoes

• 12.5°C (55°F)

• No lower than 10°C (50°F)

• 2-3 weeks

• Controlled atmospheres3% O2, <3% CO2

Relative humidity ~85%

Avoid chilling temperatures for tomatoes

Too low temperature (<10°C <50°F)Reduces flavorAffects ability to ripenIncreases decay

41 50 59 68 °F5 10 15 20 °C

4

Storage temperature, ºC

5 10 15 20

z-3-

hexa

nal,

ppm

1

2

3

4

5

6

7

8

9

10

11

12 Table-ripe tomatoes stored for 6 days

6.0

9.89.3

9.9

Low temperatures reduce aroma volatilesz-3 hexanal as example of important volatile

Cantwell, UC Davis, unpublished

More recentresearch showsthat 10°C is toolow for goodaroma profile

Stored 15 days

2.5°C 7.5°C 12.5°C

20°C20°C

Cv BobcatInitial ColorStage = 3

2.5°C = 36°F7.5°C = 45°F12.5°C = 55°F

It is quitecommon thattomatoes areheld at 45°F.

Results indecay andpoor color.

Cv Bobcat, round field-grown variety2006 Ara and Cantwell

Days

3 6 9 12 15 18 21 24 27

Col

or

scor

e

1

2

3

4

5

6

Color Changesduring storage and after transfer to 20°C at 7, 14 and 21 days

6 = full red

12°C (55°F)10°C (50°F)7.5°C (45°F)5°C (41°F)

Cv Bobcat2006 Ara and Cantwell

Days

3 6 9 12 15 18 21 24 27

Co

lor

sco

re

1

2

3

4

5

6

Color Changesduring storage and after transfer to 20°C at 7, 14 and 21 days

6 = full red

12°C (55°F)10°C (50°F)7.5°C (45°F)5°C (41°F)

Hu

e co

lor

valu

e

40

42

44

46

48

50

52

12.5°C (55°F) 10°C (50°F)

7.5C°C (45°F)5°C (41°F)

Storage Temperature

LSD.05

Weeks storage

0 1 2 3

Lyco

pen

e, m

g/k

g F

W

35

40

45

50

55

60

A. Red color, Hue

B. Lycopene

12.5°C (55°F) 10°C (50°F)

7.5C°C (45°F)5°C (41°F)

Storage Temperature

LSD.05

Most of the fruit stored longer than1 week at 5 and 7.5°C (41 and 45°F) had decay and did not ripen.

Fruit stored at 5°C and 7.5°C that did not decay, lacked the ability to develop red color.

Lower the hue value, redder the fruit

Initial 30%

Round Tomato (cv Bobcat) stored 4 weeks + 2 days

Initial stage = 3

10°C (50°F) 7.5°C (45°F) 5°C (41°F)

5

5°C 9d

20°C 9d

10°C 9d

Visual qualityof packagedgrape tomatoesafter 9 days.

9=ex

celle

nt, 1

=un

usea

ble

5

6

7

8

9

20°C (68°F)15°C (59°F)10°C (50°F)5°C (41°F)

perc

ent

0

2

4

6

8

10

Days

0 3 6 9 12 15 18

New

tons

-for

ce

9

10

11

12

13

14

Days

0 3 6 9 12 15 18

Hue

col

or v

alue

33

36

39

42

45

48

51

54

A. Visual Quality B. Weight Loss

C. Firmness D. Red color

LSD.05

Grape Tomatoes (cv Amsterdam) stored in consumer packaging at 4 temperatures. Cantwell, unpublished, 2004.

Storage for grape tomatoes is somewhat different due to water loss; High quality grape tomatoes on salad trays at 5°C okay for 14-18 days

Shelf-life/Storage/Ripening Conditions

Temperature and ripening of different tomato types; update conventional tomato chart

Impact of lower than recommended storage temperature; slight chilling; differences among varieties

Ripening Temperature and ethylene treatment Temperature and RH -Impact on firmness and gloss

Table 1. Effect of temperature on ripening rates of conventional tomatoes.

Days to full red color at indicated temperature

Ripeness stage

12.5C55F

15C59F

17.5C64F

20C68F

22.5C72F

25C77F

Mature-green

18 15 12 10 8 7

Breaker 16 13 10 8 6 5

Turning 13 10 8 6 4 3

Pink 10 8 6 4 3 2

Res

pir

atio

n (µ

L C

O2. g

-h)

5

10

15

20

25

A. Respiration

cv Bobcataverage 6 fruitsinitial stage =1 (MG)

Eth

yle

ne

pro

du

ctio

n (

nL.

g-h

)

0

2

4

6

8

10

Days

0 5 10 15 20

Col

or

scor

e1=

gree

n, 6

=ta

ble-

ripe

1

2

3

4

5

6

C. Red color

B. Ethylene production

Final 20°C 15°CHue (Red color) 35.5 40.8N firmness 21.9 29.6% soluble solids 4.5 4.4% acidity 0.32 0.40

20°C (68°F)

15°C (59°F)

Tomato Ripening & Temperature

15°C allows ripening to continuebut at much slower rate than at 20°C

Similar to ripening bananas andother fruits

Temp. °C

Initial color

Days to TR

Weight loss %

FirmnessN

Red color Hue

SS%

Sugarmg/ml

TA%

Vit. Cmg/100ml

20 2 13 4.3 27.0 35.0 4.0 18.3 0.26 21.8

12.5 2 32 4.2 28.2 38.3 4.0 17.8 0.26 24.3

20 3 11 3.4 23.0 35.9 4.0 20.8 0.26 27.4

12.5 3 22 3.0 28.5 39.4 4.2 19.5 0.28 29.9

20 4 7 2.2 25.5 37.2 4.0 20.2 0.29 26.6

12.5 4 18 2.2 26.3 37.6 4.1 19.9 0.27 30.3

20 5 5 2.0 23.0 39.7 3.9 19.4 0.28 27.4

12.5 5 18 2.3 20.5 37.5 4.2 22.7 0.26 29.3

Average 20C 9 3.0 24.6 37.0 4.0 19.7 0.27 25.8

Average 12.5C 22 2.9 23.4 38.2 4.1 20.0 0.27 28.4

LSD.05 0.5 3.7 1.8 0.2 2.9 ns 3.5

Tomatoes ripen into similar quality in temperature range from 12.5-20°C

Cantwell, 2003#7, unpublished; cv Bobcat

Res

pir

atio

n µ

L C

O2. g

-1h

-1

0

5

10

15

20

25

30

35

40A. Respiration

Eth

yle

ne p

rod

uct

ion

nL

. g-1

h-1

0

1

2

3

4

5

6

7

Days from Breaker Stage

-2 0 2 4 6 8 10

Co

lor

Sco

re (

1=

gre

en

, 6=

tab

le-r

ipe

)

1

2

3

4

5

6

B. Ethylene production

C. Color change

Mature-green Fruit

12.5°C (55°F) 20°C (68°F)30°C (86°F)

Cv Mountain Fresh

Impact of Temperature on Tomato RipeningRespiration, Ethylene and Color Avoid Ripening above 20°C

6

Tomatoes and 1-MCP (SmartFresh™)

• 300ppb 1-MCP at 20°C ~ 12.5°C Storage

• 1-MCP is a powerful regulator of tomato fruit ripening

• Easy to overdose and have poor final quality (red fruit)

• Important to determine where 1-MCP can add value to the tomato category

Review Paper: The use of 1-MCP on fruits and vegetables. C.B. Watkins. 2006. Postharvest Biology Technology 24: 389-409.

cv Bobcat 14 days at 20°C Treated 12h with 1-MCP at Breaker stage

100 ppb 300 ppb 600 ppb

12.5°C 15°C 20°C

cv Bobcat 14 days from Breaker stage

Ethylene Treatment for Ripening MG fruit

• Ethylene concentration: 10-100 ppm• Temperature: 15-25°C (60 to 77°F)• Relative humidity: 90-95%• Duration: 24 to 72 hours• Air circulation: sufficient for distribution

of ethylene in ripening room• Ventilation: sufficient to prevent

accumulation of CO2 which reduces effectiveness of ethylene

7

Checker boarding

Should never be aproblem with vine ripe tomatoes!

At Packhouse

At Distribution

Vine-ripe Greenhouse Tomato

Why did they have variability?What changes did they make?

Sensory Evaluation ProjectFruit with decay and other defects.

Tomato typeNumber

fruit evaluated

% decay

% defects Type of defect

MG ripenedField-grown

480 1.0 11.9 Poor color, sunburn, too soft

PinksField-grown

360 10.8 8.9 Poor color, excessively soft

Hothouse 140 1.5 2.1 Shrivel, mechanical damage

TOV 260 0.0 4.0 Immature fruit, poor color

Test#2. Tomatoes packed commercially; VR field fruit not in commercial box

VR field Hothouse MG field TOV

Tomato quality• Variety and maturity at harvest

• Minimize physical injury

• Storage: temperature & duration– 12.5°C (55°F), No lower than 10°C (50°F)

– 2-3 weeks

• Ripening conditions– Temperature 15-20°C

– High humidity

– If MG fruit, 100 ppm ethylene 3 days

http://www.unitedfresh.org/newsviews/food_safety_resource_center/fresh_tomato_supply_chain

8

Quality Criteria for Marketing Chiles and Peppers

• Shape, size and color typical of cultivar• Bright glossy appearance; • Green stem & calyx• No decay, damage, defects• Firm, little water loss• Flavor and pungency typical of cultivar

cm3 o

r g

0

50

100

150

200

250

300

350

mm

, N

or

%

0

1

2

3

4

5

6

7

8

9

Volume (cm3)

Fresh weight (g)

Pericarp thickness (mm) Pericarp firmness (N) % Soluble solids

Weeks from anthesis

0 2 4 6 8 10 12

colo

r va

lue

0

20

40

60

80

100

120

140

Chroma

Hue

Weeks from anthesis

0 2 4 6 8 10 12

mg

. kg

-1. -

h-1

or

ng. k

g-1

. h-1

x 1

0-1

0

5

10

15

20

25

30

35

40

45Respiration

Ethylene production

A B

C

Bell Pepper (cv. Domino)

Growth & Ripening

Tadesse et al., 2002. Scientia Hort 93: 91.

Color changesDuring ripeningOf peppers

Days at 20°C (68°F)

0 2 4 6 8 10 12 14

Fru

it su

rfac

e w

ith c

olo

r, %

0

10

20

30

40

50

60

70

80

90

100

cv. Orobelle

Mature green in AirMature green in Ethylene

Breaker in Air Breaker in Ethylene

Bell peppers generally do not respond to ethylene Temperature has the greatest effect on color change or ripening. Holding at 25-29°C (77-84°F) maximizes rate of color change

Days

1 2 3 4 5 6 7 8

% c

olo

r0

10

20

30

40

50

60

70

80

90

100Color change of breaker stage fruitTest 1

2.5°C 36°F10°C 50°F15°C 59°F20°C 68°F25°C 77°F

cv Yolo Wonder

To maximize quality and shelf-life of colored peppers, harvest at no more than 80-90% color; color change continues after harvest even under typical storage temperatures. Storage Conditions for Peppers

• High RH reduces water loss but may increase superficial decay on stems

• Avoid condensation, will favor bacterial decay on damaged areas

• Temperature: 5-10°C (41-50°F); 7.5°C (45°F) is best

• Shelf-life: 2-3 weeks

• CA not provide much benefit; low O2 retards color change

9

Chilling Injury Symptoms on Peppers and Chiles

Ripe peppers are more chilling tolerant than green peppersLim et al., 2007. HortScience 42:1659; 14d 1°C (A) +2d 20°C (B)

Green

Breaker

Ripe

Pe

rce

nt

we

igh

t lo

ss

0.0

0.5

1.0

1.5

2.0

2.5

B. Weight Loss

9=

exc

elle

nt,

7=

fair,

5=

po

or

6

7

8

9

A. Visual Quality

12.5°C 55°F 10°C 50°F 7.5°C 45°F 5°C 41°F 2.5°C 36°F

LSD.05

Days

7 14 21 28

To

tal c

ap

saic

ino

ids

(mg

/10

0g

DW

)

0

20

40

60

80C. Capsaicin Content

LSD.05

Jalapeño Peppersstored at 5 temperaturesfor up to 4 weeks (evaluated without transfer)

No significant changes in capsaicin content of Jalapeñopeppers with time or storage temperature--in chiles of marketable quality

Similar results with Habaneroand Serrano chiles—no significantChanges in capsaicin content

3 productions systems, MexicoPhotos Jose Aguiar, UCR

Field Pack Operations

Field Harvest: defect sorting

Plastic totes into refrigeratedtrailer for transport to packing house

10

Weight sizer

Volume sizer

Hand packing

GREENHOUSE PEPPERSPeppers transferred to shallow trailerGentle dry dumpSingulation for weight sizerWater spray to remove dust (chlorinated)Sponge rollers to remove excess water

0

1

2

3

4

5

6

7

0 30 60 90 120

Minutes at Sun Exposition

% W

eig

ht

Lo

ss

SUN 7 d 7.5C 2 d 20C

Weight loss in bell pepper fruits during periods of direct sun exposure, with storage for 7 days at 7.5°C and finally total weight loss after additional 2 days at 20°C to simulate marketing.

0 d

Storage7d 7.5°C

Shelf7d 7.5°C

+2d 20°C

0.5 h 1.0 h 1.5 h sun

1 hour exposure to direct sun reduces marketable quality

1 5

4

3

2

Pepper Shrivel Rating Scale

Weight loss1 = 2%2 = 4-5%3 = 7-8%4 = 10-12%5 = 15-17%

% Weight Loss

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

9=

exce

llen

t, 1

=u

nuse

ab

le

0

1

2

3

4

5

6

7

8

9 A. Visual QualityLSD.05=0.4

Delays to cool should be less than:9 hours at 20-25°C (68-77°F) 6 hours at 37°C (99°F).

Weight loss, Appearance and Firmness

Importance of water loss

<3% no visual effect, texture3-5% visual quality affected>5% shrivel, lose salability

Salable WeightFresh AppearanceTexture

Water loss is cumulative

Repacking Peppers at Distribution Center, 2010