Postharvest Technology Flashcards
GROWTH, DEVELOPMENT, MATURATION, RIPENING, SENESCENCE:
Sprouting (onions, tubers, root crops)
Rooting (onions, root crops)
Elongation and curvature (asparagus)
Seed germination (lemon, tomato, pepper
Transpiration refers to
the process by which water is lost from the surface of fruits and vegetables to the surrounding air. This happens naturally as the produce “breathes” through tiny openings called stomata
During respiration, stored carbohydrates are broken down, and water vapor is released.
This water loss, combined with transpiration, leads to the drying out of the produce
Biological Spoilage (Pests, Microbiological Spoilage, Physiological Factors
Post-harvest technologies such as controlled atmosphere storage, refrigeration, and chemical treatments (e.g., fungicides) help reduce biological spoilage
Biochemical Spoilage (Enzymatic, Oxidation, Non-Enzymatic Changes):
Technologies such as cold storage, antioxidants, and modified atmosphere packaging help prevent enzymatic browning and oxidation
Physical Spoilage (Bruising, Crushing, Wilting, Texture, and Moisture Changes):
Proper packaging, temperature, and moisture control maintain the texture and prevent dehydration or wilting.
- Grading and Sorting:
automated sorting systems, which use sensors and imaging, allow producers to classify fruits and vegetables based on size, color, ripeness, and external appearance.
- Market Segmentation:
, producers can cater to diverse market segments, including retail, food service, and industrial sectors, increasing product diversity and overall value.
- Quality Preservation for Different Grades:
Post-harvest technologies such as modified atmosphere packaging (MAP) or cold storage help maintain different quality levels
. Customized Packaging Solutions
Based on quality classification, different packaging technologies (e.g., vacuum-sealed, tray-packed, or bulk-packaged) can be applied, enhancing the product diversity offered to different consumers.
For instance:
- High-quality produce may be sold in attractive consumer-ready packages for retail.
- Lower grades might be sold in bulk packaging for processing or industrial use
- Minimizing Food Waste and Maximizing Value
Classifying produce based on quality ensures that even slightly damaged or subpar fruits and vegetables are utilized for other purposes, such as making purees, soups, sauces, or snack products like chips and dried fruits.
This not only reduces food waste but also increases product diversity by offering different products made from the same raw material.
- Enhancing Consumer Choice:
providing consumers with choices based on quality and price.
For example:
-Organic versus conventional produce.
-Fresh, ready-to-eat versus processed and frozen versions of the same product.
-Premium fruit trays for gift-giving versus bulk produce for cooking and processing
The importance of postharvest technology
Reduction of Post-Harvest Losses
Extension of Shelf Life
Maintenance of Nutritional Quality
Food Safety
Economic Impact
Sustainability
Chlorine-based Sanitizers (Sodium Hypochlorite):
Typically used at 50–200 ppm of free chlorine for washing produce. After washing, the produce must be rinsed thoroughly with potable water to remove any chlorine residue.
Ozone (O3):
Usage: Ozone is a powerful oxidizing agent used in water to sanitize fresh produce. It is effective against a wide range of microorganisms.
Hydrogen Peroxide (H2O2):
Hydrogen peroxide is often used as a sanitizer for fresh produce and works by oxidizing cell membranes of microorganisms.
Sorting/grading
(i) size and shape.
(ii) Colour homogeneity
(iii) Sweetness/sourness and moisture
(iv) Defects, disease and contamination
Waxing
Description: A thin layer of edible wax is applied to the surface of fruits and vegetables to reduce moisture loss, enhance appearance, and protect against physical damage and contamination.
water loss and respiration,
contribute to cold injury or chill damage
Water Loss through Stomata
In cold environments, the stomata may stay open, causing the cells to lose water faster than it can be replaced. This leads to dehydration of the tissue, resulting in wilting, shriveling, or surface damage in fruits and vegetables.
Reduced Metabolic Functions
The reduced respiration affects energy production, making it difficult for the cells to maintain their normal functions.
Result: Chill Starvation
The combination of water loss and metabolic slowdown leads to what is called “chill starvation.”
the produce is unable to maintain normal physiological functions due to:
Dehydration (water loss through stomata),
Lack of energy (due to reduced respiration),
Weakened cell membranes (due to reduced fatty acid synthesis).
Proper packaging plays a crucial role in extending the shelf life of produce
by allowing sufficient ventilation to prevent moisture buildup, which can lead to spoilage or mold growth, while also ensuring the packaging is sturdy enough to prevent the produce from being crushed or damaged during transportation and storage
