AgSc 111

• Maturity


  (in postharvest physiology) the stage at which a commodity has reached a sufficient stage of development that after harvesting and postharvest handling, its quality will be at least the minimum acceptable to the ultimate consumer
• Importance of maturation


  • Sensory and Nutritional Quality
  • Use - fresh market or Processed
  • Adequate shelf-life
  • Facilitate marketing—standards
  • Productivity
• Consequences of harvesting too immature


  • Poor taste and flavor
  • Fruit will not ripen
  • Susceptible to water loss
  • Susceptible of damage
  • Susceptible to pathogens
• Consequences of harvesting too mature


  • Short shelf life
  • Poor texture; soft fruit
  • Overripe taste and off flavor
  • Susceptible to pathogens
• Physiological maturity


  The stage of development when a plant part will continue development even if detached; mature fruits

  
• Horticultural maturity


  The stage of development when a plant part possesses the necessary characteristics for use by consumer

  
• Examples of crops that are mature horticulturally/immature physiologically


  • Sweet corn
  • Peas
  • Snap beans
  • Summer squash
  • Cucumber
  • Bean sprouts
• Examples of crops that are mature horticulturally/mature physiologically


  • Winter squash
  • Melons
  • Tomato
  • Pepper
• Maturity indices


  Tools to gauge the level of maturity in crops, aiding in the prediction of the optimal harvest time and evaluating crop quality, such as suitability for fresh consumption or processing
• Maturity indices should be user-friendly and non-invasive, allowing for easy and non-destructive assessment
• Practical uses of maturity indices


  • Export markets frequently provide guidelines specifying the acceptable minimum and maximum levels of maturity for a particular commodity
  • To secure premium prices, marketing strategies consider supply and demand dynamics
  • Adjusting harvest and shipping times requires assessing crop maturity to maintain quality
  • Efficient labor utilization relies on gauging crop maturity to schedule the start and end dates of harvesting
• Subjective maturity indices


  Rely on grower's/picker's experience; some have been used as basis in developing objective indices (appearance, touch, smell, resonance, sweetness)
• Objective maturity indices


  Based on measurable or quantifiable parameters using instruments or calculations (chemical constituents, computation, dimensional fullness of finger in bananas)
• Subjective maturity indices


  • Shape and size
  • Peel color
  • Pedicel drying or abscission zone development
  • Bloom production
  • Compactness (solidity, firmness)
  • Drying of plant part
  • Aroma development
  • Sound produced when tapped
• Growing degree days (GDD)


  Heat units used to estimate the growth and development of certain crops during the growing season
• Color


  Use of electronic colorimeter; L*, a*, b*, chroma (C*) and hue angle (hº); often expressed as hº; on-line color sorting machines used in citrus, mango, tomato and apple packinghouses function similar to lab equipment
• Soluble solids content (SSC)


  Sugar content; use of refractometers (hand-held, benchtop, electronic); ranges 0-5, 0-20, 10-50; need regular calibration
• Acidity


  Measured by titration; sugar to acid ratio (SSC:acid) often better related to fruit palatability than either SSC or acid level alone
• Firmness


  Use of penetrometer/ pressure tester or Instron instrument (compression); best to automate to remove bias of individual testers; e.g. apple firmness should be 14 lb force
• Starch content


  Iodine test (iodine reacts with starch resulting in blue to black color); 2% iodine solution; used mainly for apples
• Other objective maturity indices


  • Oil content – used in avocado cultivars high in oil content
  • Dry matter content – used in avocado and kiwifruit
  • Specific gravity – relative gravity or weight of produce as compared to water (specific gravity =1) at ambient temperature; increases with maturity; e.g. in mango, sinkers more mature than floaters
• For most produce, combining different indices to determine optimum harvest maturity would be more ideal than relying on a single index
• A reliable maturity index of a specific fruit or vegetable should be specific to a cultivar and should not be affected by climatic variations, plant size and vigor, and soil and cultural conditions

  
• Maturity indices of selected fruits and vegetables


  • Banana
  • Pineapple
  • Tomato
  • Cauliflower

  
• Harvesting


  • Crucial operation determining both the quality and storage longevity of produce, playing a pivotal role in averting significant losses
  • Maintaining a high level of field hygiene is imperative during the harvesting process
  • Careful execution at the appropriate time is essential to avoid damaging the commodity
• Harvesting operation


  • Identification and judging the maturity of fruits/vegetables
  • Selection of mature fruits/vegetables
  • Detaching or separating of the fruits/vegetables from the plant
  • Collection of matured fruits/vegetables

  
• Manual harvesting


  Common in Asian countries, labor and time consuming, advantageous to minimize physical injury & for selective harvesting
• Manual harvesting methods


  • Ladder / bag picking method
  • Poles/ Clippers method
  • Harvesting by means of cutting knives
  • Harvesting by means of digging tools
• Manual harvesting of leafy greens


  • Carefully uprooted or cut at the base with a sharp knife to reduce effort and picker fatigue
  • Use small, smooth-surfaced field containers (e.g. plastic or metal bucket); total weight per container <20 kg for one person to easily carry
  • If wooden crates or bamboo baskets are used, use liners such as fresh leaves, sacks or used newsprint to protect produce from damage
• Mechanical harvesting


  Use of numbers of mechanical devices for harvesting the produce on commercial scale
• Mechanical harvesting


  • Shake and catch action
  • Could save labor and management costs as high as 30-45%
  • Increases physical injury
  • Increases cost in culling undesired produce and foreign matter
  • Only recommended for large-scale operations where labor is scarce & expensive
• Factors affecting harvesting time


  • Harvesting during cooler parts of the day reduces the product's heat load and enhances worker efficiency
  • Harvesting under direct sunlight exposes the produce to high temperatures, necessitating their transfer to shaded areas to allow for heat dissipation
  • Harvesting early in the morning may lead to increased damage, as the produce tends to be turgid and brittle, with a higher flow of latex
  • Leafy greens, such as Pakchoi, exhibit their highest water content at 0400h and 2000h, leading to a slower rate of wilting
  • Harvesting later in the day provides an additional advantage, as sugar levels are higher due to photosynthesis, resulting in a slower rate of yellowing
• Field handling


  • Meticulous handling of produce in the field is essential to minimize physical injury and maintain the quality of the harvest
  • Refraining from dropping or dragging harvesting or field containers, avoiding the throwing of produce into containers, and preventing overpacking of containers
  • Keeping produce out of direct sunlight and swiftly moving it to a shaded, well-ventilated area or packinghouse
• Field handling operations


  • Sorting
  • Dehanding (in the case of bananas)
  • Draining latex
  • Packing
  • Transporting the produce to packing houses, customers, or markets
• Hygiene for harvesting apparatus


  • Tools/equipment should be checked for damage and repaired or disposed of properly
  • Regular cleaning is essential, with daily washing using soap solution or sanitized water
  • Harvesting bags should be washed after the season, while crates must be cleaned daily
  • Store all equipment in a closed facility to protect from rats and birds, potential sources of contaminants