vegetable crops – plsc 451/551 lesson 7, harvest, handling, packing instructor: stephen l. love...

Vegetable Crops – PLSC 451/551 Lesson 7, Harvest, Handling, Packing

Instructor:Stephen L. LoveAberdeen R & E Center1693 S 2700 WAberdeen, ID 83210Phone: 397-4181 Fax: 397-4311Email: slove@uidaho.edu

Vegetable Handling

Maximum quality exists at the moment of harvest

Quality MaintenanceLimit mechanical injury

Limit losses to disease

Meet biochemical and culinary quality specifications

Vegetable Handling - Principles

Factors that determine post-harvest qualityStage of crop maturityHarvest and handling injuryWater lossTemperature during harvest, transport and

storageRate of respiration, ripening, and breakdownInfection with pathogenic organisms

Crop Maturity

Harvest Timing

Factors that modify harvest decisions:CropMarket availabilityCommodity priceIntended use

Crop Maturity

Basis for harvest timing decisions

Harvest index based on:SizeColorAbility to withstand handling, storage, and

transportTendency for post-harvest ripening

Crop Maturity

Examples of maturity index characteristics:

Cantaloupe: fruit color and stem slip

Tomato: fruit color

Broccoli: head size and floral development

Lettuce: head and/or leaf size

Sweet corn: kernel color, kernel starchiness

Crop Maturity

Examples of maturity index characteristics:

Cantaloupe: fruit color and stem slip

Tomato: fruit color

Broccoli: head size and floral development

Lettuce: head and/or leaf size

Sweet corn: kernel color, kernel starchiness

Crop Maturity

Examples of maturity index characteristics:

Cantaloupe: fruit color and stem slip

Tomato: fruit color

Broccoli: head size and floral development

Lettuce: head and/or leaf size

Sweet corn: kernel color, kernel starchiness

Crop Maturity

Examples of maturity index characteristics:

Cantaloupe: fruit color and stem slip

Tomato: fruit color

Broccoli: head size and floral development

Lettuce: head and/or leaf size

Sweet corn: kernel color, kernel starchiness

Crop Maturity

Examples of maturity index characteristics:

Cantaloupe: fruit color and stem slip

Tomato: fruit color

Broccoli: head size and floral development

Lettuce: head and/or leaf size

Sweet corn: kernel color, kernel starchiness

Crop Maturity

Examples of maturity index characteristics:

Onion: drying and falling of tops

Potato: top death and skin-set

Carrot: length and diameter of root

Radish: size, time from planting

Cucumbers: size, color, firmness

Crop Maturity

Examples of maturity index characteristics:

Onion: drying and falling of tops

Potato: top death and skin-set

Carrot: length and diameter of root

Radish: size, time from planting

Cucumbers: size, color, firmness

Crop Maturity

Examples of maturity index characteristics:

Onion: drying and falling of tops

Potato: top death and skin-set

Carrot: length and diameter of root

Radish: size, time from planting

Cucumbers: size, color, firmness

Crop Maturity

Examples of maturity index characteristics:

Onion: drying and falling of tops

Potato: top death and skin-set

Carrot: length and diameter of root

Radish: size, time from planting

Cucumbers: size, color, firmness

Crop Maturity

Examples of maturity index characteristics:

Onion: drying and falling of tops

Potato: top death and skin-set

Carrot: length and diameter of root

Radish: size, time from planting

Cucumbers: size, color, firmness

Crop Maturity

Some crops can be harvested at multiple stages of growth, but handling practices will be modified at each stage.

Tomato - green pick, pink stage, vine ripened

Squash – immature, mature

Potato – new potatoes, mature

Harvest and Handling Injury

Most vegetable losses result from harvest and handling damage

Blemishes resulting from bruising

Increased respiration

Moisture loss from damaged tissue

Entrance wounds for pathogens

Impact of injury on ripening and shelf-life of tomatoes

Handling Injury

Effect of drop height and picking stage:

Percent bruised fruit

0 in drop, green stage – 0%

12 in drop, green stage – 1.8%

0 in drop, breaker stage – 0%

12 in drop, breaker stage – 24.3%

Harvest Practices

Mechanical harvest:

Root crops, tuber crops, bulb crops, many processing vegetables

Manual Harvest

Most vegetables including leafy greens, salad crops, fruit vegetables, crucifers, and herbs

Harvest Practices

Mechanical harvest:

Root crops, tuber crops, bulb crops, many processing vegetables

Manual Harvest

Most vegetables including leafy greens, salad crops, fruit vegetables, crucifers, and herbs

Harvest Practices

Preventing mechanical harvest damage

Harvest only well-matured crops

Proper machine calibration and maintenance

Padding on all surfaces

Minimize drop heights

Operate all equipment at full capacity

Harvest Practices

Preventing manual harvest damage

Train labor to handle produce gentlyHarvest at the proper stage of maturityField pack where feasible, minimize handlingHave labor trim fingernails or wear glovesUse padding on all conveyor surfaces and

packing containers

Water Loss

Effects of water loss:

Quality reduction – shriveling and desiccation

Excessive trim losses

Loss of salable weight

Water Loss

Methods for reducing water loss:

Harvest and handle in cool conditions

Harvest well-watered crops

Rapidly cool produce to proper storage temperatures

Employ humidification procedures

Water Loss

Optimum humidity level:Asparagus 95-100%Beet 98-100%Sweet corn 95-98%Garlic 60-70%Lettuce 98-100%Watermelon 90%Pepper (dry) 60%Pepper (bell) 90-95%

Temperature

Impact of improper temperatures

Above optimumHigh rate of respiration and ripeningHigh rate of water lossRapid growth of decay organisms

Below optimumFrost injuryCold injury

Temperature

Vegetables that require cooling

Leafy greens and salad crops

Vegetable fruits with high respiration rates

Any crop with a short shelf-life

All crops when temperatures are very high

Temperature

Cooling techniques and equipment

Room cooling

Forced-air cooling

Hydro-cooling

Top-icing

Vacuum cooling

Evaporative cooling

Top-down cooling room

Forced-air cooling room

Portable cooling chamber

Hydro-cooler

Hand hydro-cooling

Icing

Vacuum cooler

Temperature

Optimum storage temps, cooling method, and shelf life

Broccoli 32 HC,ICE 10-14 dCabbage 32 RM 5-6 mCucumber 50 HC 10-14 dOkra 45 FA 7-10 dSquash 50 RM 2-8 mSweet corn 32 HC,VAC 5-8 dGinger 60 RM 6 m

Packing, Storing, Marketing

The shelf life and period of effective storage of vegetables is determined by respiration and ripening.

Respiration: the process by which cells produce energy through oxidation of sugars and other energy-rich compounds

Ripening: irreversible softening and sweetening process by which vegetables become more edible

Packing, Storing, Marketing

Vegetable crops differ widely with respect to rates of respiration and ripening

Root Crops: low rates of respiration and small ripening changes

Packing, Storing, Marketing

Vegetable crops differ widely with respect to rates of respiration and ripening

Leafy Crops: high rates of respiration and no or minor ripening changes

Packing, Storing, Marketing

Vegetable crops differ widely with respect to rates of respiration and ripening

Mature fruits: intermediate rate of respiration and significant ripening changes.

Packing, Storing, Marketing

Vegetable crops differ widely with respect to rates of respiration and ripening

Immature Fruit Crops: high rates of respiration and incomplete ripening processes

Rate of Respiration, Ripening

Sample of respiration rates

Very Low: peanut

Low: potato, onion, sweet potato

Moderate: tomato, lettuce, pepper

High: green onions, snap beans

Very High: broccoli, peas, sweet corn

Rate of Respiration, Ripening

Importance of respiration rate

High respiration

= rapid changes (decline) in quality

= need for rapid handling and transport

= short storage capabilities

= short shelf life

Rate of Respiration, Ripening

Impact of temperature

Respiration can be controlled by lowering temperature

For every 18 degree F above optimum, the rate of deterioration doubles or triples (i.e. sweet corn at 50 (32) has shelf life of 2-4 days (4-8)

Ripening, Production of Ethylene

Vegetable that produce or are sensitive

Produce:

cantaloupe, tomato, pepper

many tree fruits often shipped with vegetables

Sensitive:

tomato, lettuce, cabbage, cauliflower, eggplant, okra, pepper, squash, watermelon

Ethylene Injury

Symptoms on Vegetables

Carrots – bitternessCole Crops – turn yellow and limpCucumbers – turn yellow and develop soft spotsAsparagus – become fibrous and woodyLettuce – develop rust-spotsSquash – turn yellow and develop soft spots

Rot and Breakdown

Rot in storage requires three things:

Susceptible host (vegetable)

All vegetable crop are prone to some disease

Pathogenic organism

Mostly fungal or bacterial

Proper conditions or environment

Temperature and humidity are critical

Rot and Breakdown

Conditions that increase incidence of rot

Entry wounds and tissue damage

High humidity

High temperature

Lack of adequate ventilation

Packing Vegetables

Importance of proper packaging

Provides conditions for quality maintenance

Improves shelf life

Identifies the produce

Simplifies shipping

Creates sales appeal

Packing Vegetables

Common steps in packaging produce

1. Washing

2. Presizing

3. Grading and Sizing

4. Trimming, waxing, cosmetic improvement

5. Packaging

6. Inspection

7. Palletizing

Packing Vegetables

Common steps in packaging produce

1. Washing

2. Presizing

3. Grading and Sizing

4. Trimming, waxing, cosmetic improvement

5. Packaging

6. Inspection

7. Palletizing

Packing Vegetables

Common steps in packaging produce

1. Washing

2. Presizing

3. Grading and Sizing

4. Trimming, waxing, cosmetic improvement

5. Packaging

6. Inspection

7. Palletizing

Packing Vegetables

Common steps in packaging produce

1. Washing

2. Presizing

3. Grading and Sizing

4. Trimming, waxing, cosmetic improvement

5. Packaging

6. Inspection

7. Palletizing

Packing Vegetables

Common steps in packaging produce

1. Washing

2. Presizing

3. Grading and Sizing

4. Trimming, waxing, cosmetic improvement

5. Packaging

6. Inspection

7. Palletizing

Packing Vegetables

Common steps in packaging produce

1. Washing

2. Presizing

3. Grading and Sizing

4. Trimming, waxing, cosmetic improvement

5. Packaging

6. Inspection

7. Palletizing

Packing Vegetables

Common steps in packaging produce

1. Washing

2. Presizing

3. Grading and Sizing

4. Trimming, waxing, cosmetic improvement

5. Packaging

6. Inspection

7. Palletizing

Packing Vegetables

Similar process, smaller scale, less automation

Grade Standards for Vegetables

Purpose of grade standards

Ensure quality for the seller and buyer

Provide a common language for quality

Provide legal protection for all parties

Provide third party confirmation

Grade Standards for Vegetables

Origin of published grade standards

USDA/AMS

State departments of agriculture

Local marketing order organizations

Local grower groups

Individual sellers and buyers

Grade Standards for Vegetables

USDA Standards

158 published standards85 vegetable cropsInclude specifications for size, shape, defects,

damage

Web site: http://www.ams.usda.gov/gac/index.htm

Grade Standards for Vegetables

Enforcement of grade standards

Inspections conducted by Federal/State inspectors

Packing-site inspections

Shipping point inspections

Receiving point inspections

Grade Standards for Vegetables

Application of standards

Commercial U.S. Production

USDA-AMS grading standards applied

Organic/Market Production

Variable: grade and/or organic standards often applied in developed countries

Worldwide subsistence production

No application of standards