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Distribution warehouses and Storage roomsLettuce Apples
Manage Ethylene Effects
1. AvoidanceProducts, combustion engines, smoke
2. RemovalVentilation (1 air exchange per hour), oxidation, absorption
3. Inhibition of productionLow temperature, chemical inhibitors of enzymes, antisense
technology
4. Inhibition of actionLow temperature, high CO2, low O2, STS, 1-MCP (Smartfresh™)
5. GermplasmSelection of mutants and molecular modification
Control 300 600ppb 1-MCP
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Factors contributing to postharvest losses
• Temperature• Water loss
• Damage
• Diseases
• Ethylene
• Continued growth
• Physiological disorders
TIME
Continued growth‐‐temperatureContinued growth‐‐temperature
• Sprouting (potato, onion, garlic)
• Rooting (onion, potato)
• Growth away from gravity (asparagus, flowers)
• Internal seed growth (cucumber, beans)
• Opening of immature buds (broccoli)
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• Disorders resulting from abnormal conditions during production and handling
• Abnormal temperatures
• Extended storage
• Abnormal gases
• Nutritional imbalance
PHYSIOLOGICAL DISORDERS
Factors that influence U.S. Consumers’ Produce Purchases
0 20 40 60 80 100 120
Fresh Trends, 1990. Vance Research Services.
% of Consumers
Taste/FlavorFreshness, ripenessAppearance
Nutritional valuePrice
Storage lifeCertified safe, testing
Convenient, preparedSizeIn-season
Bulk (loose) displayCalorie content
Growing region/countryOrganic
PrepackagedBrand name
Food Safety is Assumed
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Postharvest Problem…Quality is maximized when the product is
harvested more mature or ripe, whereas shelf‐and storage life are extended if the product is
harvested less mature or unripe….
Toivonen, P. 2007. Fruit maturation and ripening and their relationship to quality. Stewart Postharvest Review 2:7.
ACIDSSUGARS
Low High
LowInsipid,
tastelessSweet
Moderate to High
Sour, tartBest flavor
combination
Soluble solids measured by a refractometer = sugars, but also organic acids, soluble pectins, anthocyanins, phenolics, ascorbic acid, others
Taste and the Sugar:Acid Ratio
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Based on Appearance (Visual Quality)
Based on Flavor & Nutritional Quality
Based on Firmness & Texture
0 20 40 60 80 100%
Postharvest Life Under Optimum Conditions
Kader, A.A. 2003. A Perspective on Postharvest Horticulture. HortScience 38: 1004
Need more critical postharvest studies that determine flavor life as well as appearance life. Reassess current recommendations for whole and fresh-cut products.
General Principles
• Fresher the product (time), better the quality and flavor– True for vegetables
– More complicated for fruits that require ripening
• Adhering to storage and handling guidelines results in better flavor
• Postharvest treatments may extend the storage -life but not necessary preserve flavor
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1-2 days to harvest, cool, store
1-2 days local transport
7-21 days truck or marine transport
1-3 days to distribution center
1-3 days at retail
1-3 days at consumer
Total = 12 - 34 days
Product under ideal conditions?UNLIKELY!
How do we successfully move so many productsthrough diverse transportation/distribution channels? How long to market? What storage life is needed? What quality is needed?
Factors contributing to postharvest losses
• Respiration
• Water loss
• Damage
• Diseases
• Ethylene
• Continued growth
• Physiological disorders
• Light
TIME andTEMPERATURE
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Profitable Horticulture Depends on Good Postharvest Handling
• Reduce losses!• Increase sales and consumption
• Improve quality– Taste– Nutritional
• New products• Niche markets• Lightly processed• Food safety