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