1

Examples of products

Physiology of fresh-cut products

Fresh-cut Products: Overview and Challenges

Physiology of fresh cut products

Preparation and handling

Quality aspects of fresh-cut products

Marita Cantwellmicantwell@ucdavis.eduhttp://postharvest.ucdavis.eduPostharvest Technology Short Course June 2011Ch. 36 Postharvest Technology Book

"Fresh-cut produce" is defined as any fresh fruit or vegetable or any combination thereof that has been physically altered from its original form, but remains in a fresh state. R dl f di i h b

DEFINITION Fresh-cut Produce

• Minimally Processed

• Lightly Processed

• Partially Processed

• PrepreparedRegardless of commodity, it has been trimmed, peeled, washed and cut into 100% usable product that is subsequently bagged or prepackaged to offer consumers high nutrition, convenience and value while still maintaining freshness.

• Fresh Processed

• Pre-cut

• Value-added

IFPA/UFPA

Estimated Projected National Retail Fresh-Cut Produce Sales:

$5.3 Billion in 2009 vs. $5.4 in 2008

Packaged Fruit 9%

Sources: The Perishables Group and estimates by Roberta Cook

Packaged salads

58.2%Vegetables* 32.8%

Examples fresh-cut fruit products

FreshFresh--cut Vegetablescut Vegetables• Lettuces: cleaned, chopped, shredded• Spinach, leafy greens, washed & trimmed • Broccoli & cauliflower florets• Cabbage, shredded • Carrots, baby, sticks, shredded• Celery sticks• Onions, whole peeled, slices, diced• Potatoes & other roots: peeled, sliced, diced• Mushrooms sliced• Jicama, Squash, cucumber slices, dices• Garlic, fresh peeled, slices• Tomato and pepper slices

Sweetpotato for Food service Many garlic productsSweetpotato for Food service

Strips taro, celeriac, sweetpotato

Many garlic products

Steam in pouch B.sprouts & asparagus

2

CARROT CHIPS™

CARROT DIPPERS™

http://www.grimmway.com

CARROT SNACKSTM

for Horses!Food ServicePresentations

Resealable bags

Single serveSnack packs

Rigid containersand bowls

Packaging is a key enabling technology

Resealable bags

Biobased packagingPLA resin

Active packaging Intelligent/SmartPackaging

IFPA, 2004. Fresh-cut Produce Fuels an America on the go. 58 pp.

Immediate Physical Effects

Mechanical shock to tissueBruises, cracks, fractures in tissue

Removal of protective epidermal layerAlter gas diffusionP id t f t i tProvide entry for contaminants

Cell fluids on cut surface Reduced gas diffusionProvides substrate for microbes

Exposure to contaminantsMicrobial ,Chemical

Abrasion peeling of carrots leads to fragmented cell walls that dry out and result in “white blush”;can rehydrate carrots.

New equipment peels and then

Diagrams from Saltveit, UC Davis

q p pcuts the carrots; have less problem with “white blush”

Physiological Effects of Fresh-cut Processing

• Increased respiration rates

• Altered ethylene production rates

• Increases in other biochemical reactions– Discoloration and Color

– Texture

– Aroma and Flavor

– Nutritional quality

Main strategy to minimize changes in physiology is low temperature

Respiration rates of Intact and Shredded Lettuce

Res

pira

tion

(µ

l CO

2. g

-1 h

-1)

0

5

10

15

20 Shredded Lettuce

Days storage

0 1 2 3 4 5 6 7 8 9

Res

pira

tion

(µ

l CO

2. g

-1 h

-1)

0

5

10

15

20 Intact Lettuce2.5°C (36°F)

5°C (41°F)

7.5°C (45°F)

10°C (50°F)

Shredding greatly increased respiration rates Temperature control is

extremely important

3

• Low temperature minimizes wound response

(µL

CO

2. g

-1 h

-1)

6

7

8

9

10

11

12 Yellow Onion

Intact

Peeled

Diced

on

ra

te (

µL

CO

2. g

-1h-1

)

60

80

100

120

140

Intact

Chopped, Manual

Chopped, Commercial

Green Onions

• Diced onions discolor, decay, soften and lose fluid more readily than whole peeled onions

Storage Temperature

Res

pir

ati

on

(

0

1

2

3

4

5

6

0°C 5°C 10°C

Temperature

Re

spira

tio

0

20

40

0°C32°F

5°C41°F

10°C50°F

15°C59°F

20°C68°F

More cutting, higher respiration rates Low temperature minimizes respiration Dices discolor, decay, soften and lose fluid

more readily than whole peeled onions

Intact and Intact and FreshFresh--cut Kalecut Kale

Respiration rate (mL CO2 kg-1 h-1 )

P d t 0ºC 5ºC 10ºC 15ºCProduct 0ºC 5ºC 10ºC 15ºC

Full size leaves 8 12 29 33

Small leaves 14 21 42 57

Chopped (2 x 2 cm pieces full size leaves)

15 23 46 53

Shredded (0.3 cm pieces full size leaves)

17 28 59 68

Enzymatic Browning

PALPhenylalanine cinnamic acid other phenolics

PPO

Wounds induce phenolic metabolismWounds induce phenolic metabolismLeading to unsightly brown pigmentsLeading to unsightly brown pigments

+ O2 (o-Diphenol oxidase)(Laccase)

Complex brown polymers quinones

PAL = phenylalanine ammonia-lyasePPO = polyphenol oxidase

CutCut--Edge DiscolorationEdge Discoloration

PPOPPOQuinonesQuinonesPhenolicsPhenolics

CondensationCondensation

Rx’sRx’s

Colored Colored PigmentsPigmentspH 6-7

Oxygen

Copper

PHE(Phenyalanine)

PALPAL

Key Browning Reactions

pp

Type 1 Fresh-cut BrowningPAL activity induced, low pre-formed phenolic content (e.g.lettuce)

Type 2 Fresh-cut BrowningPlenty of PPO and pre-formed phenolics present (e.g. apples)

5

4

Salad Lettuce Cut edge browningWound induction of PAL

and brown pigments Lettuce types and varieties

differ in PAL and browning

3

2

1Days at 5°C (41°F)

0 1 2 3 4 5 6 7

PA

L

acti

vit

y (

µm

ol c

inn

am

ic a

cid

. g-1

. h-1

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0Green LeafRed LeafButterhead

IcebergRomaine

5% LSD

pira

tion

rate

(µ

L/g-

h)

9

12

15

18

21 A. Intact leavesHeart Young Midsize Full size

B. Salad-cut leaves (2 x 2 cm)

Romaine lettuce: leaf position/age effect on respiration, discoloration and composition

Days at 5°C (41°F)

1 2 3 4 5 6 7 8

Res

p

0

3

6

Days at 5°C (41°F)

1 2 3 4 5 6 7 8

Phenolics highest in outer leaves; browning highest in outer leaves Sugars highest in heart leaves Chlorophyll/carotenoids highest in outer leaves Vitamin C not much affected by leaf age or position

Ermen, Hong, Cantwell, 2006

4

Prevention of enzymatic/oxidative browning

• Refrigeration (slows enzymatic reactions)

• Exclusion of oxygen (CA, MAP, edible films)

• Inhibition of PAL (lettuces & vegs)• Inhibition of PAL (lettuces & vegs)

• Inhibition of PPO (fruits)

• Use of reducing agents (ascorbic acid, etc.)

• Other chemical agents

Air

Iceberg Lettuce 15 days

Air

0°C 5°C 10°C

CA

(1%O2 + 9%CO2)

CA

Harvest Trim, core, defect removal Cool and/or MA Dump, mechanical cut

Lettuce Salad Preparation

Dump, mechanical cut Cooling, disinfection Drying, centrifugation Component blendingWeigh and package Metal detector, pack, palletize Temporary cold storage

Knife/Cutting Blade Sharpness Cut cleanly not crush Better shelf-life Less browning of cut edges

CarrotSharp Razor Dull Knife

Quality of Cut Iceberg Lettuce(Huxsoll & Bolin, 1977)

Scanning electron microscopy, Tatsumi & Watada, 1991

5

Washing Disinfecting Rapid cooling Cut to 2 inch sections

Processing Baby Peeled Carrots

Cut to 2 inch sections Mechanical Peeling Mechanical shaping Disinfection Cooling Computerized quality and color sorting Packaging (form, fill, seal)

Many large volume (lettuces) products are mechanically cut, but manual preparation generally results in superior quality

cutting romaine by hand; eliminate defects manually peeled garlic vs compressed air peeled broccoli and cauliflower florets manually trimmed manually trimmed and cut melons, pineapples

Cantaloupe Melon Tranlucency: Sharp vs Blunt Blades

10d

Same: Soluble solids

Days at 5°C

0 2 4 6 8 10 12

Ele

ctro

lyte

Lea

kage

(%

of

Tot

al)

28

30

32

34

36

38

40

42

44 Sharp-AirBlunt-Air Electrolyte

Leakage

TextureMicrobial growthRespiration, ethylene

Different: AppearanceColor values Ferm.volatilesElectrolyte LeakageOff-odors

Portela & Cantwell 2001 JFS 66:1265

SANITARY PLANT DESIGNFocus: Implementation of GMP’s

Rudi Groppe; http://www.heinzen.com/products/

Design efficient, easy to clean & sanitize processing plants

Mobility of equipment 2-3 areas to separate production steps The sanitation crew is as important as the

production crew

Fresh-cut Products

Food Safety Requirements

• Meticulous cleanliness of equipment, employees and product

• Constant monitoring of sanitizer activityConstant monitoring of sanitizer activity

• Rigid maintenance of refrigerated temperatures

• Complete integrity of packages

• Strict adherence to product use by dates & handling instructions

Lettuce Salad Quality Lettuce Salad Quality ParametersParameters

• Fresh appearance

• No decay

• No discoloration

• Crisp texture

• Good aroma and flavor

• Good nutritional value

To date, these quality components have beenundervaluedCurrent package atmospheres cause loss in all three

6

%

0 00

0.05

0.10

0.15

0.20

mm

ol/k

g

0 0

0.5

1.0

1.5

2.0

Sco

re (

9=e

xcel

len

t)

1

2

3

4

5

6

7

8

9Oxygen Acetaldehyde Visual Quality

0ºC10ºC20ºC

Temperature Effects on Retail Packaged Salads

0.00

Days0 4 8 12 16 20 24

%

0

5

10

15

20

25

0.0

Days0 4 8 12 16 20 24

mm

ol/k

g

0

10

20

30

40

50

60

Days0 4 8 12 16 20 24

Sco

re (5

=se

vere

)

0

1

2

3

4

5Carbon Dioxide Ethanol Off-Odors

Peiser and Cantwell

Cut Lettuce AlternativesIntact Baby sizeClean Whole leavesHearts of romaineSmall mixed lettucesOrganic Spring Mix

Rely on temperatureRely on temperatureControl; No MA usedControl; No MA used

Nutrition Fresh-cut Products• Larger piece size retains nutrients better than smaller pieces

• In packaged salads, high CO2 atmospheres can cause significant loss of Vitamin C

• Vitamin A (carotenoids) content correlated with chlorophyll concentrations

• Initial nutrient content is paramount; loss of vitamins is minimized by low temperature

Chlorophyll, mg/100g FW

0.0 0.1 0.2 0.3 0.4

Ca

rote

no

ids,

mg

/10

0g F

W

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

y = 0.157x + 0.00971R2=0.89

Cut Romaine Total Vitamin C

Days 5°C

0 3 6 9 12 15

To

tal V

it. C

(m

g/1

00g

fw

t.)

0

10

20

30

40

air

1% O2 + 10% CO2

air + 10% CO2

1% O2

LSD.05

Lettuces: Carotenoids vs Chl

0°C

5°C

Spinach, bag, 10d Damage to spinachDamage to spinach HarvestHarvest Bin dump, sort areaBin dump, sort area Wash and centrifugeWash and centrifuge

PackingPacking

10°C

Category 1 Category 3

Defect level Category %None or slight 1 and 2 34.2

Moderate damage 3 49.2

Severe damage 4 13.7

Leaf Pieces 5 2.8

Damage on commercial washedand packaged spinach (cv Space)

6

7

atu

re (

°C)

Retail Shelf

Di t

LocalDistribution

Fresh-cut produce Chill Chain Temperatures During Shipping, Distribution and Retail Display.

We can do better!!

Temperature data from a fresh-cut processor

3

4

5

0 2 3 4 5 6 7 8 9 10Days

Tem

pe

ra

1

At plant

Retail Store CoolerDistance

Transport

Problems with ice

Good temperature control throughout handling and distribution is a necessity for fresh-cut products; vertical air flow cabinets.

7

cv Dayton

Impact of temperature and CA (1%O2 + 10%CO2) on the quality of yellow fresh-cut onions

0°C 5°C 10°C

Commercial prepared red onion riand dices stored 9 days.

0 C 5 C 10 C

10 days

7.5°C (45°F)

5°C (41°F)

Relative Importance of Temperature and Modified Atmospheres for Fresh-cut melon

( )

2.5°C (36°F)

Air 1% O2 Air +10% CO2

1% O2 +10% CO2

Increased complexity and compatibility issues

Vegetable trays- want 18 day shelf-life

Products in tray and compatibility issues- raw material sourcing and handling before prepare - shelf-life of individual products in tray varies- temperature; 5°C too low for grape tomatoes- modified atmospheres—not good for all products in tray

Baby Carrots and Variety Selection

• Uniform, bright orange color

• Small or no core

• High sugars with no harshness/bitternessHigh sugars with no harshness/bitterness

• Smooth exterior to minimize peeling loss

• No green should or green core problems

• Strong tops for mechanical harvest

• Balance between juicy texture and resistance to shatter

8

Romaine 1 Romaine 2

Immature

Mature “Next Level Fresh Fruit Cuts, a division of Fruit Dynamics, Inc., Fresno, CA, has announced that after 5 years of product development, they have identified the

Fresh-cut Peach & Nectarine

IMPORTANCE OF VARIETY

Romaine 1 Romaine 2Overmature

4D 5°C Air

p , yproper cultivars, processes and packaging necessary to commercialize fresh cut peaches and nectarines, in many cases with a shelf life exceeding 15 days.”

400 varieties evaluatedFlavor profileResistance to discolorationShelf-life requirement

http://www.californiafarmer.com/story.aspx/fresh/cut/peaches/go/commercial/9/41540; Aug 2010

Genotypic Differences in Browning Potential of Apples

High Quality Raw Material is Necessary

for High Quality Fresh-cut Product

Brassicas have higher respiration rates than lettuces.Freshness of color and flavor ingredients.

Preprocessing StorageExample: Lettuce heads stored at 5°C (41°F)Longer heads are stored, greater browning on cut salad pieces

e 4

5

Days stored before processing

Browning of Cut Edges

Days after processing

1=no

ne,

5=

seve

re

1

2

3

before processing

Days after processing

0

7

14

IcebergLettuce

RomaineLettuce

4 8 12 4 8 12

Ripeness stage & storage

temperature affect Shelf-life

Slide from Gorny & Kader, UC Davis

Fresh-cut tomato for food serviceShelf-life vs qualityImportance of initial ripenessImportance of ripening conditions

ColorTextureComposition-flavor

Difference in juicepurge of 2 tomatocultivars

9

Fresh-cut Fruit Challenges• Labor Intensive Production• High Cost per pound-yields and price• Fruit availability

– Sourcing domestic and offshore– Storage history

M i t f i– Managing stage of ripeness

• Perishable cut product – softening, browning, microbial

• Flavor quality

Flavor and nutritional life is about 2/3 shelf-life (appearance)

Applies to whole productsApplies to fresh-cut products

Problem: processors and handlers of fresh-Problem: processors and handlers of freshcut products focus too much on shelf-life, not enough on flavor quality

Products Potential post-cutting storage life at 2-5ºC

VEGETABLES Days

Baby carrots, peeled onions, peeled garlic >21

Lettuce salads, whole lettuce leaves, mixes small leaves (spring mix, mesclun),spinach leaves, peeled potatoes; sliced root mixtures

14-18

Broccoli & cauliflower florets, shredded cabbage, shredded lettuce, shredded broccoli stem, celery &

t ti k

10-14

For quality and shelf-life: All cut products benefit from low temperature, some benefit from modified atmospheres, and a few benefit from additional treatments

carrot sticks

Pepper and tomato dices, cucumber slices, squash slices, mushroom slices, jicama sticks

4-9

FRUITS

Apple wedges, pineapple chunks, pomegranate arils 10-14

Strawberry slices, melon chunks, mango cubes, citrus segments, peach & pear slices, grape berries, kiwifruit slices

2-9

Maintain Quality & Safety of Fresh-cut Vegetable Products

Use highest quality raw material

Minimize mechanical damage; sharp knives Minimize mechanical damage; sharp knives

Rinse cut surfaces; remove excess water

Maintain strict sanitation; chlorinated water

Use appropriate package and atmosphere

Maintain product temperature at 1-2°C

Quality of Fresh-Cut Fruits and Vegetables

Standardization and Inspection

There are no U.S. grade standards for fresh-cut products; raw product standards apply; http://www.ams.usda.gov

The following booklet provides guidelines and definitions f i tifor inspection:

USDA. 1998. Fresh-cut produce: shipping point and market inspection instructions.Fresh products branch, Fruit & Vegetable Division, Agricultural Marketing Service, U.S. Department of Agriculture, Washington, D.C.

This publication is currently being updated

Best if used by dates

We want FRESH Fresh-cut Products!

Pure Hot House Foods, Inc.Fresh Plaza 9Feb2011

THANK YOU!