BASIC HARVEST AND POST-HARVEST
HANDLING CONSIDERATIONS FOR FRESH
FRUITS AND VEGETABLES
The maturity index for fruits and vegetables is crucial for determining the ideal time to
harvest them, affecting their storage, quality, and marketability. There are three key stages in
the life of produce: maturation, ripening, and senescence. Maturation signifies readiness for
harvest, while ripening makes the produce edible by altering taste. Senescence represents
natural degradation. Various indicators are used to determine maturity:
1. Skin Color: Some fruits change color during ripening, aiding harvest decisions.
2. Optical Methods: Light transmission measures chlorophyll content, linked to maturity.
3. Shape: The shape of the fruit can shift, indicating maturity.
4. Size: Changes in size can signal the right harvest time.
5. Aroma: Ripening fruits emit volatile chemicals with characteristic odors.
6. Fruit Opening: Certain fruits split upon full maturity, but earlier opening leads to a short
shelf life.
7. Leaf Changes: Leaf quality can show when to harvest root crops.
8. Abscission: The abscission layer's development in the fruit's stem helps determine the
harvest time.
9. Firmness: Texture changes during ripening; devices measure firmness.
10. Soluble Solids: Measurement of soluble solids and pressure testing are used as maturity
indicators for some fruits like Bartlett pears.
These indicators help determine the optimal time for harvesting fruits and vegetables to
ensure their best quality and post-harvest performance.
The maturity of fruits can be assessed using various parameters, including juice content, oil
content, dry matter percentage, sugars, starch content, acidity, and specific gravity:
1. Juice Content: As fruits mature on the tree, their juice content increases. A representative
sample of the fruit is extracted for juice, and the volume is related to its maturity. Minimum
juice content values are established for citrus fruits, as indicated in Table 2.2.
2. Oil Content and Dry Matter Percentage: Oil content can indicate fruit maturity, such as in
avocados. The oil content is determined by extracting oil from avocado pulp using solvents.
Dry matter percentage, including oil content and moisture, changes during avocado
development.
3. Moisture Content: As avocados mature, oil content increases while moisture content
decreases. Different avocado cultivars have varying moisture content levels for good
acceptability.
4. Sugars: Climacteric fruits accumulate carbohydrates as starch, which converts into sugar
during ripening. A refractometer or brix hydrometer measures sugar content in fruit juice,
indicating maturity.
5. Starch Content: Measuring starch content is a reliable technique for determining pear
maturity. Cut fruit pieces are dipped in a solution to stain starch blue-black, indicating
readiness for harvest.
6. Acidity: The acidity of fruits changes during maturation. Acidity can be measured by
extracting juice and titrating it against a standard alkaline solution, often in relation to soluble
solids to determine the brix: acid ratio.
7. Specific Gravity: Specific gravity, indicating the relative weight of solids or liquids
compared to distilled water, increases as a fruit matures. It's used less frequently for
determining harvest time but is utilized for post-harvest grading based on different maturities.
These different maturity indicators are used to gauge the optimal time for harvesting various
fruits, ensuring their quality, flavor, and post-harvest performance.
Tools and techniques for harvesting, packing, and transporting fruits and vegetables play a
crucial role in preserving their quality:
1. **Harvesting Tools:** Depending on the fruit or vegetable, various tools are used for
harvesting, such as secateurs, knives, picking shears, and pole-mounted shears. Cushioning
materials are placed around trees to prevent damage to dropped fruits. Harvesting bags with
shoulder or waist slings are utilized for citrus and avocados, and plastic buckets are suitable
for easily crushed fruits like tomatoes. Commercial growers use bulk bins for large-scale
harvesting.
2. **Packing and Transport:**
- **Polyethylene Bags:** Used for packing banana bunches in the field, preventing damage
during transportation.
- **Plastic Field Boxes:** Made of materials like polyvinyl chloride, polypropylene, or
polyethylene. They nest inside each other when empty and stack securely when full.
- **Wooden Field Boxes:** Made of thin wood pieces bound together. Economical and
non-returnable, but offer less protection during transport.
- **Bulk Bins:** Larger capacity bins (200-500 kg) made of wood or plastic are used for
efficient and durable transportation. They offer better protection and are common for various
fruits and vegetables.
Harvesting, packing, and transporting techniques are carefully selected to ensure that the
produce reaches packinghouses or markets in the best possible condition, preserving its
quality and minimizing damage.
The post-harvest handling and storage practices for fruits and vegetables involve various
techniques to maintain their quality and extend their shelf life:
1. **Cooling Techniques:**
- **Vacuum Cooling:** Effective for leafy crops like lettuce, vacuum cooling reduces
temperature quickly using a vacuum chamber or during vacuum cooling operations. Suitable
for crops with higher mass-to-surface area ratios.
- **Hydrovacuum Cooling:** Combines vacuum cooling with water application, suitable for
crops like lettuce. Ineffective for crops with thick wax cuticles like tomatoes.
2. **Recommended Minimum Storage Temperatures:**
- Storage temperatures range from -1 to 13°C, depending on perishability.
- Perishable fruits like berries can be stored at -1 to 4°C for 1-5 weeks.
- Less perishable fruits like mandarins can be stored at 5-9°C for 2-5 weeks.
- Highly perishable vegetables like broccoli can be stored at -1-4°C for 1-4 weeks.
- Non-perishable vegetables like carrots can be stored at 5-9°C for 12-28 weeks.
3. **High Temperatures:**
- Exposure to high temperatures during post-harvest reduces storage life.
- Beneficial for curing root crops, drying bulb crops, and controlling diseases and pests.
- Used in combination with ethylene to initiate ripening or improve skin color in fruits.
4. **Storage Methods:**
- Various storage methods exist, including in situ, sand or coir, pits, clamps, windbreaks,
cellars, barns, evaporative cooling, and night ventilation.
- **In Situ:** Delay harvest until needed, suitable for root crops but can expose crops to
freezing.
- **Sand or Coir:** Cover commodities with sand for longer storage periods.
- **Pits or Trenches:** Lined with straw, filled with produce, and covered with soil for
ventilation.
- **Clamps:** Elongated conical heaps of potatoes covered with straw and soil.
- **Windbreaks:** Wooden stakes with platforms and chicken wire used for onion storage.
- **Cellars:** Underground or partly underground rooms used to store produce in varying
climates.
- **Barns:** Large farm buildings used for sheltering and storing agricultural products.
- **Evaporative Cooling:** Air passed through water-evaporating pads to achieve cooling.
- **Night Ventilation:** Utilizing temperature variations between day and night for cooling.
- **Controlled Atmospheres:** Gastight chambers with specific gas blends used for fruit
storage, particularly apples.
By employing these techniques, farmers and producers can optimize the storage conditions
of fruits and vegetables, ensuring they maintain their quality, extend shelf life, and reach
consumers in optimal condition.
Pest control and preventing decay in crops involve several techniques to maintain product
quality:
1. **Hot Water Treatment:**
- Immersing crops in hot water before storage or marketing can control diseases.
- Anthracnose, caused by the fungus Colletotrichum spp., can be controlled with this
method.
- Combining fungicides with hot water is effective for disease control.
- Recommended conditions for hot water and fungicide treatments vary based on fruit and
fungus type.
2. **Temperature Management:**
- Storage conditions significantly affect crop decay.
- Too low temperatures during refrigeration can cause injury.
- High temperatures lead to tissue softening and bacterial diseases.
3. **Microbial Impact on Decay:**
- Microorganisms cause physical loss of edible matter in fruits and vegetables.
- Decay damage can result in partial or total loss of produce.
By utilizing hot water treatments, managing temperature conditions, and understanding the
role of microorganisms in decay, farmers and producers can effectively control pests and
minimize decay in fruits and vegetables, preserving their quality and increasing their shelf
life.
