Postharvest Handling

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Postharvest Handling

• November 16 17

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What is Postharvest Handling?

• Postharvest practices
• Take full advantage the quality potential
• Reduce the rate of quality loss
• Why are postharvest practices done?
• Vegetables are living tissues that undergo
  continuous change after harvest
• Rapid deterioration can occur
• Can affect quality of vegetable
• Freshness and nutritional
• Safety of the vegetable
• Pesticide residues
• Microbiological organisms

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Deterioration Factors

• Biological
• Respiration
• CHO, fats and proteins break down releases heat
  and CO2 gas
• respiration cooling storage life
• High respiration crops (short storage life)
• Broccoli, lettuce, peas, sweet corn, spinach
• and watercress
• Low respiration crops (long storage life)
• Onions, potatoes, sweet potatoes
• Ethylene production
• Natural product of plant metabolism (can be good
  and bad)
• rate of senescence (aging) storage life
• with maturity, physical injury, disease,
  high temp., water stress

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Deterioration Factors

• Compositional changes
• Loss of chlorophyll (green)
• Gain of red, yellow, or orange
• Tomatoes, squashes, pumpkins, carrots, peppers,
  muskmelons
• Starch to sugar at low temps.
• Parsnips, sweet potatoes
• Breakdown of sugars and increase in softening
• Increased lignin toughening
• Asparagus and root vegetables
• Loss of minerals (vitamin C)
• Transpiration / Water loss
• Major cause of storage deterioration many
  influences
• 80-95 water by weight
• 3-8 of water loss causes decreased quality

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Deterioration Factors

• Condition of crop
• Physical condition does not improve in storage
• Damage - decay organisms, increase water loss,
  increase respiration and ethylene production
• Growth and development
• Sprouting potatoes, onions, garlic and root
  crops - utlization and deterioration.
• Rooting onions and root crops undesirable.
• Growth asparagus - toughness and
  palatability.
• Seed germination inside the fruit tomato and
  pepper -

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Deterioration Factors

• Environmental
• Temperature
• Most important affects deterioration
• Affects respiration and ethylene production.
• Maximum storage life minimum safe T should be
  kept.
• Relative Humidity
• Influence water loss.
• Produces some physiological disorders.
• Optimum relative humidity is about 90 to 100.

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Deterioration Factors

• Atmospheric composition
• O2 and CO2 controlled or uncontrolled can
  either or decay.
• 1-3 O2 lowest limit tolerated (below this
  off-flavors and off-odors)
• Ethylene
• Sources contaminant - engines
• (combustion), ripening rooms,
• and ripening fruits.
• Reduce the life of vegetables
• (sensitive to it)
• removal is important during storage -

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Deterioration Factors

• Light
• Greening exposure to light
• problem for potatoes, onions, garlic,
• and Belgian endive.
• Sanitation
• Essential to maintain and minimize
• contamination by decay organisms.
• Harvesting equipment, field bins, trucks,
• packinghouse lines, and storage rooms
• must be maintained clean

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Harvesting
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• When?
• Maximum quality to the consumer.
• When the product can tolerate harvest,
  handling, packing, storage, and transportation
• Harvesting sometimes not equal to best quality or
  profitability.
• Timing on maturation if mechanical harvested
  (whole plant).
• Price demand factors that affect when to
  harvest

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Harvesting

• Hand vs. Mechanical Harvesting
• US most vegetables are harvested by hand
• Correct training to pickers can reduce cost,
  losses, and maintain quality.
• Mechanical aids are used by pickers
• Mechanical harvesting commodities harvested at
  one time no sensitive to mechanical injury.
• Machines are incapable of selective harvesting
  (problem)
• Mechanization efficiency of harvesting and
  damage to the products

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misscitrus.com
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Preparing for Fresh Market

• In a Packing House
• Receiving
• Cleaning
• Pre-sizing
• Trimming
• Sorting
• Waxing
• Sizing
• Curing
• Grading
• Packaging
• Packing
• Ripening Initiation

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Cooling Vegetable Crops

• Precooling
• Immediately after harvest best quality.
• Rapid removal of the heat from the field
  separated from the cold storage room.
• Methods for precooling
• Room Cooling
• Forced-Air Cooling
• (Pressure Cooling)
• Hydrocooling
• Package icing

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Vegetable Storage

• Cold Storage
• Mechanical refrigeration to control T
• Field Storage
• Cabbage, potatoes, and root crops stored in the
  field trenches, pits, mounds, or clamps (freezing
  weather)
• Unrefrigerated Storage
• Heavily insulated places products to be stored
  for long periods of time potatoes, onions,
  winter squashes, and root crops.

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Vegetable Storage

• Night Air Storage
• In warmer climates modification of
  unrefrigerated storage temperature during
  nights is low.
• Ventilation is open at night (isolation during
  day keeps low temperature)
• High Altitude Storage
• Source of cold.
• Air temperature decreases by 5.5F for every 1000
  feet increase of altitude.

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General Storage Conditions

• Leafy and Succulent Vegetables
• Low monetary value per unit weight.
• Inexpensive packaging, handling, and
  transportation.
• Underground Vegetables
• Exposed to soil-borne contamination during
  harvest and handling (mechanical harvesting
  damage)
• Storage requires wound-healing limit
  infection.
• Fruit Vegetables
• Warm- vs cool-season crops chilling injury
• Not adapted to long storage

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Specific Storage Conditions

• Beans
• Highly perishable, rapid cooling is required
  after harvesting.
• Wash to remove waste.
• Optimum storage 40-45F and 90-95 relative
  humidity (storage life 7-10 days)
• Cole Crops
• Optimum storage 32F and 98-100 relative
  humidity (storage life late cabbage 6 months,
  early cabbage 1-2 months)
• No stored with fruits (ethylene produces damage)

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Specific Storage Conditions

• Carrots
• The roots are high in starch. Low temperatures
  (32F) converts starch to sugar and increases
  quality.
• Cold storage (32F, 98-100 relative humidity)
• Storage life, 4 to 6 months.
• Celery
• Packed into crates hydrocooling
• Packed into paper cartons vacuum cooling
• Cooled as soon as possible, 32F and 98-100
  relative humidity. Storage life, 2-3 months.

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Specific Storage Conditions

• Cucumbers
• Hydrocool to remove heat from field (soon)
• Cold storage 50-55F and 95 relative humidity.
  Storage life 10-14 days.
• No storage with fruits - release ethylene
  (yellowing accelerated)
• Lettuce, spinach and leafy greens
• Cold storage 32F and high humidity. Storage life
  3-4 weeks.
• Freezing injury temperature lt 31.7F

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Specific Storage Conditions

• Melons
• Reduce the interior T of melons with 40F.
• Methods include hydrocooling, forced-air cooling,
  and top-icing or package-icing.
• Storage 36-41F muskmelons, 45F for honeydews,
  and 50-60F for watermelons (all 90-95 humidity)
• Onions and Alliums
• Dry bulbs storage 32F and 65-70 relative
  humidity (several months)
• Sprout inhibitor maleic hydrazide is used.

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Specific Storage Conditions

• Peas
• Rapid removal of heat from the field.
• Storage 32F and 95-98 relative humidity
  (storage life 1-2 weeks)
• Peppers
• Fruits are graded water 128F and 500ppm
  chlorine to control bacterial rots.
• Wax is applied to reduce moisture loss.
• Storage 45-50F and 90-95 relative humidity
  (storage life up to 3 weeks)

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Specific Storage Conditions

• Potatoes and sweet potatoes (steps)
• Curing 55-60F with high relative humidity for
  2-3 weeks
• Holding 38-40F to prevent accumulation of
  sugars (100 relative humidity)
• Removal 50-60F recondition the tubers before
  shipping to markets (reduce damage)
• Sweet Corn
• The sugar decreases and the starch increases with
  temperature.
• Field heat must be removed as soon as possible.
• Storage 32F and 95-98 humidity 5 to 8 days

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Specific Storage Conditions

• Tomatoes
• Ripening rooms ethylene is applied to tomatoes
  before shipping.
• Storage 57-61F (up to 3 weeks).
• Eggplants
• Sensitive to chilling injury below 50F.
• Deteriorate rapidly at warm temperatures
• Storage 46-54F and 90-95 relative humidity
  (storage life 7-10 days)

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Specific Storage Conditions

• Pumpkins and Squashes
• Hard-rind squashes adapter for long-storage
• Curing 10 days at 80-85F and 80 relative
  humidity.
• Storage, winter squashes 50F and 50-70
  relative humidity summer squashes 41-50F and
  95 relative humidity

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Presentation References

• Sargent, S.A. Ritenour, M.A. and J.K. Brecht.
  2007.Handling, Cooling and Sanitation Techniques
  for Maintaining Postharvest Quality. p. 97-106.
  In Olson, S.M. and E. Simonne (eds.) Vegetable
  production handbook for Florida. University of
  Florida, IFAS Extension.
• Kerbel, E.L. 2002. Postharvest Handling of
  Vegetables p. 181-208. In Swaider, J.M. and G.W.
  Ware. (eds.) Producing Vegetable Crops. 5th ed.
  Interstate Publishers, Inc., Danville, IL.

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Todays Field Questions for Garden Notebook

• What are the two main considerations in
  postharvest handling?
• What is the main priority after harvest? (Hint
  temperature related.)
• Name one factor that contributes to deterioration
  and how it reduces fruit quality.
• Name and briefly describe one aspect of the
  packing house operation.
• What are the factors that influence storage life?