postharvest handling update cool season vegetables

7/29/2019 Postharvest Handling Update Cool Season Vegetables

1/30

Postharvest Handling Update

Cool Season Vegetables

Marita Cantwell, UC Davis

[email protected]://postharvest.ucdavis.edu

UCCE Vegetable Pest Management and Postharvest Issues

Santa Maria, June 9, 2010


2/30

http://postharvest.ucdavis.edu

Produce Facts

Harvest indices Quality indices

Temperature and RH

Freezing point/damage

Respiration rates

Ethylene production

Effects of ethylene Effects of modified

atmospheres

Physiological disorders

Postharvest diseases

Mechanical injury

PHOTOS

140FruitsVegetablesFlowers


3/30

Causes of Quality & Postharvest Losses

Leafy VegetablesLettuces

Spinach

CabbageChard

Broccoli

Celery

HerbsEndives

Asparagus

Green Onions

Water loss

Mechanical damage

Loss of chlorophyll andother nutrients

Respiration rates

Microbial growth

Sensitivity to ethylene


4/30

Fresh Produce

Deterioration

Metabolic changes:

respiration, ethylene, texture, aroma, etc.

Growth and development

Transpiration

Mechanical injury Physiological disorders

Decay; microbial growth

Temperature

Affects All

Causes ofDeterioration


5/30

Postharvest Handling Update

Cool Season Vegetables Broccoli

Iced to iceless product; firmness and water loss

Specialty Brassicas Compare postharvest performance to broccoli

Fresh-cut and modified atmospheres Response of broccoli and sugar snap peas

Cauliflower --needs postharvest work

Cabbage Quality and Temperature

Lettuce Varieties Fresh-cut performance


6/30

Storage temperature

D

ays

(toinitiate

yellowing)

0

5

10

15

20

25

30

35 Broccoli Shelf-life & Temperature

032

2.536

541

7.545

1050

12.555

1559

20C68F

cv. Legacy

Fresh appearance

Green florets

Tender stem

No discoloration

No breakage

No decay

No off-odors


7/30

mg/100gFW

0

5

10

15

20

25

mg/100gFW

0

1

2

3

4

Days

0 5 10 15 20 25

mg

/100gFW

0

5

1015

20

25

30

35

40

Days

0 5 10 15 20 25

mg

/100gFW

0

5

10

15

20

25

Chlorophyll Carotenoids

Ascorbic Acid Sugars

0C (32F)10C (50F)

20C (68F)

Limit ofSalability

Broccoli Compositional Quality and Storage Temperature

Cantwell, unpublished


8/30

Days

0 2 4 6 8 10 12 14 16 18

Co

lorscore,

5=d

arkgreen,

1=ye

llow

1

2

3

4

5

Mature Kale Leaves 20C (68F)15C (59F)10C (50F)5C (41F)

Days

0 2 4 6 8 10 12 14 16 18

Immature Kale Leaves

LSD.05

Loss of green color by mature and immature Kale leaves storedat 4 temperatures for up to 18 days.

5 4 3 2 1


9/30

10C Air 1-MCP, 10C Air 10C C2H4 1-MCP, 10C C2H4

12 days; 8 ppm C2H4;500 ppb 1-MCP

Collards

5C Air 10C Air 10C C2H4

1-MCP=1-methyl-cyclopropene, SmartFresh, AgroFresh


10/30

Chlorop

hy

ll,mg

/gFW

0.3

0.4

0.5

0.6

0.7

0.8

0C Control 0C 1-MCP

5C Control 5C 1-MCP

10C Control 10C 1-MCP

A. Chlorophyll

LSD.05

Days

0 5 10 15

Sugar,

mg

/gFW

3

4

5

6

7

8B. Sugar

LSD.05

VitaminC,mg/100gFW

40

80

120

160

200

240

280

0C Control 0C 1-MCP

5C Control 5C 1-MCP

10C Control 10C 1-MCP

A. Vitamin C (AA + DHA)

LSD.05

Days

0 5 10 15

Glucoraphinin,mole/gDW

5

6

7

8

9

10

11

12

13

14

15B. Glucoraphinin

LSD.05

Broccoli and Temperature and 1-MCP (no ethylene exposure)

Glucoraphin produces Sulforaphane potent Phase 2 Enzyme Inducer, inhibit cancer


11/30

Specialty Brassicas Comparative Study

Gai-lan

Choi-sum

Broccoli raab, rapini

Broccolini

Florets Stem Tissue

Component

Initial 5C,

8d

10C

8d

Initial 5C

8d

10C

8d

Total sugars, mg/gFW 5.2 4.5 3.7 17.4 14.4 12.0

Ammonia, mole/100gFW 1.1 1.4 2.3 0.5 1.0 1.1Antioxidant activity

mg Trolox/100g FW

117 100 92 47 43 32

Vitamin C, mg/100g FW 235 176 112 87 86 88

M. Cefola, G. Hong, M. Cantwell, R. Paiva e G. Colelli. 2009

Marketable quality

Compositional qualityResponse to Temperature

Response to atmospheres

Broccoli raab


12/30

0

200

400

600

800

1000

1200

1400

1600

0C 5C 10C

AMMONIA

INC

REASE

25

27

29

31

33

35

37

39

TOTALGS

ACTIVITY

AMMONIA INCREASE GS TOT

6 days, data of Eghle Catalano, 2007

Changes in ammonia andGS activity in Spinach

Days

0 2 4 6 8 10 12 14 16 18

mg

/gfres

hweig

ht

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

2.5C 36F

5C 41F

7.5C 45F

10C 50F

Ammonia concentration

Changes in ammonia in spinachat 4 temperatures over 18 days


13/30

mo

le/100g

FW

0

50

100

150

200

250

300

350

400

450A. Ethanol

mo

le/100g

FW

0

10

20

30

40

50

60

70

80

90 B. Acetaldehyde

Days at 5C

0 3 6 9 12 15 18

g/g

FW

0

10

20

30

40

50

60

70

80

Days at 5C

0 3 6 9 12 15 18

g/gFW

45

50

55

60

65

70C. Ammonia D. Sugars

LSD.05

3%O2+7%CO2

3%O2+12%CO23%O2+18%CO210%O2+12%CO2

Air

3%O2+7%CO2

3%O2+12%CO23%O2+18%CO210%O2+12%CO2

Air

Test #2


14/30

18 days at 5C (41F)

A B C D E3+7 3+12 3+18 10+12 Air

DAMAGING

Air=Best quality


15/30

Iceless BroccoliTemperature-yellowing

Moisture loss-softening

0C with very high humidity MA: 5-8% O2 + 7-10% CO2

Broccoli Storage Conditions


16/30

Table 1. Broccoli head firmness and compactness scoring and the relationship to firmness

measurements on texture analyzer. This table based on preliminary 2009 data.

Subjective

score

Description Objective firmness

N compression

force*

5 Heads hard, very tight and firm 65-100N

4 Heads firm, a few outer florets may be loosened 50-80

3 Heads moderately firm, with some florets loosened** 40-60

2 Heads moderately soft, with most florets loosened 25-40

1 Heads soft, with extensive loosening of florets 10-25

*Heads compressed with a flat disc to a depth of 7.5 mm

**A score of 3 is likely the limit of marketability at retail.


17/30

Days at 7.5C

0 1 2 3 4

%

We

ightloss

0

1

2

3

4

5

6

7

8

Curve 1, y= 1.55x+ 0.34; R2

= 0.98

Curve 2, y= 1.72x+ 0.36; R2

= 0.98

Curve 1 original firmness techniqueCurve 2, modified technique, mark

A. % Weight Loss

Days at 7.5C

0 1 2 3 4 5 6 7

%Firm

nessloss

0

10

20

30

40

50

60

70

80

90

100

Curve 1 original firmness technique

Curve 2, modified technique, mark

B. % Firmness Loss

Minimize delay from harvest to cooling

Use plastic liners to reduce water loss

Keep it cold


18/30

2.5C (36F) 5C (41F) 7.5C (45F)

14 days air


19/30

14 days 5C (41F)

5% O2 5% O2 + 7.5% CO2 5% O2 + 15% CO2


20/30

14d 5C

Quality ProblemsGrayingLoss of fluidOff-odor

Air 1%O2 +15% CO2


21/30

RESEARCH TO DO

Evaluate the performance of cultivars forquality of fresh market and fresh-cut product

Evaluate the impact of initial postharvesthandling on the shelf-life and quality offresh-cut cauliflower florets.

Evaluate the impact of production conditions(seasonablity, fertilization, irrigation) on thequality and shelf-life of cauliflower florets

Cauliflower Qualitycolor is cream white

freedom from mechanical injury

freedom from decay

overall attractive appearance

no discoloration on cut edges

minimal number of small pieces; good integrity of cut florets

good aroma and odor as fresh or microwaved food

retain high content of sugars and Vitamin C

Days

1 2 3 4 5 6

Resp

ira

tion

(LCO

2/g-h

)

0

20

40

60

80

100

120

140 0C (32F)

5C (41F)

10C (50F)15C (59F)20C (68F)

A. Heads

Days

1 2 3 4 5 6

B. Florets


22/30

Napa or Chinese cabbage

Black Speck Disorder


23/30

Cultivar

1 2 3 4 5 6 7 8 9

Blackspec

kindex

0

50

100

150

200

250

Air

Ethylene

Cv #1= T-7402= Yuki3= Spring Flavor4= Southern King

5= New Summer6= Chacha7= China Express8= Blues9= WR-70

Black speckdevelopmenton Napa cabbage

stored in air or in

ethylene is the same.

PAL enzyme

levels similar; 1-MCP does not reduce

black speck.

Cultivars vary

greatly in their

susceptibility toblack speck.

Black speck index = black speck score multiplied by % extension.

Black Speck Disorder on Chinese Cabbage


24/30

Cabbage Quality and TemperatureCDFA WIC Stores Small Farm Program Project

Shermain Hardesty, Lucia Kaiser, and Advisors

Retail handlinggood to poor conditions

Impact on marketability and nutritional value

conditions to retain 80% original nutrition

Vitamin C, Antioxidant Activity, Carotenoids

Wide range of temperatures (0-29C; 32-84F)

Cabbage performs well over temp rangeshould be

available in all WIC stores


25/30

Fresh-cut Lettuces

Varieties of Iceberg, Romaine and Crosses

Performance as fresh-cut product

Visual quality score

Discoloration

Decay

Respiration rates

Phenolics and phenolic enzymes (PAL, PPO)

Composition

Number leaves per head

% dry weight Sugars

Chlorophyll and carotenoids

Vitamin C

Ammonia


26/30

Discoloration Rating Scale for Romaine

13

4 5

2


27/30

Totalsu

gars(mg/gfwt.)

0

5

10

15

0 days

7 days

HeartInner

Young Midsize Full sizeOuter

Leaf Position

Total sugars

LSD.05

Leaf Position

To

talascorbicac

id(mg

/100g

fwt.)

0

10

20

30

40 0 days

7 days

LSD.05

Vitamin C (Total Ascorbic Acid)

HeartInner

Young Midsize Full sizeOuter

Romaine

lettuce


28/30

Variety

1 2 3 4 5 6 7 8 9 10 11 12 13

Russe

tSpo

tting

Score

1=none,

9=severe

1

2

3

4

5

6

7

8

1=Sonoma2=Spreckles3=Salinas 5214=Raider5=Salinas 5176=Buena Vista7=Stinger8=Van Sal 2109=Salinas

10=Ace11=Champ12=Salinas 8813=Ridgemark

A. Iceberg Lettuces

Variety

1 2 3 4 5 6 7

B. Romaine Lettuces

1=Paris Island Cos2=Romo3=Red Eye Cos4=Gx8005=Corazon

6=Red Hot Cos7=Nero

Development of Russet Spot Disorder on Iceberg and Romaine Lettuces.Intact heads were stored in 5ppm ethylene at 5C (41F) plus 1 week in air.

Cantwell, UC Davis, unpublished


29/30

Is Temperature a Quality Issueor a Food Safety Issue?

Prevention of Contamination is most important Time and Temperature are Amplifiers of Risk

Slide from Trevor Suslow, UC Davis


30/30

1) Harvest at correct maturity

2) Reduce physical handling

3) Protect product from sun

4) Keep packingline simple and

clean; ensure good worker hygiene5) Select, classify, and pack carefully

6) Align cartons, strap pallet

7) Cool as soon as possible

8) Know market and product requirements9) Coordinate efficient & rapid handling

10)Train and compensate workers adequately

10 Basic Postharvest Principles

postharvest handling update cool season vegetables

Documents