PostHarvest Technology - Module content

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There are 19 major topics in this module

Introduction to Postharvest Technology
Definition and importance
Post harvest losses of agricultural products
Causes of losses
• Quantitative, qualitative, nutritional and socio-economic losses
• Loss assessment and methods for reducing losses

Biological /physiological and environmental factors affecting shelf life
Pre -harvest factors affecting post harvest
• Ethylene production
• Compositional changes
• Growth and development
• Transpiration
• Physiological breakdown due to freezing, chilling injury, heat injury, etc.
• Physical damage
• Pathological breakdown

Environmental factors influencing Deterioration
• Relative Humidity
• Atmospheric composition
• Ethylene
• Light
Post harvest technology procedures
Temperature management procedures
• Control of Relative Humidity

Supplements to temp. & humidity management
Curing of certain roots, bulbs and tuber crops
• Cleaning followed by removal of excess surface moisture
• Sorting to eliminate defects
• Waxing and other surface coatings
• Film wrapping
• Heat treatment (hot water or air, vapor heat)
• Treatment with post harvest fungicides
• Sprout inhibitors
• Special chemical treatments (scald inhibitors, calcium, growth regulators
• Fumigation for insect control
• Ethylene treatment (degreening, ripening)
Maturation and Maturity Indices
• Indices of maturity
• Characteristics of maturity index
• Developing maturity indices
• Estimating maturity 
   Physical (Size, shape, surface characteristics, abscission, color, texture)
    Chemical changes(TSS, starch, sugar/acid ratio)
    Physiological changes
    Changing respiration and ethylene production

Harvesting systems
Hand harvesting
• Mechanical harvesting
Preparation for fresh market
Labor planning and training
• Field containers
• Transportation from field
• Temperature protection
• Cooling
    Methods of cooling
Preparation for packing
• Sorting and grading (export grades/domestic grades), cleaning/washing, waxing, disease control).
• Purpose of packaging
• Hand packing
• Mechanical packs 

Storage systems
Storage considerations
    Temperature
     Humidity
Grain storage and storage structures
• Survey on post harvest loss assessment of grains
• Grain processing- threshing, drying, hulling,
milling and expelling

Mechanical Refrigeration (fruits and vegetables)
Alternative refrigeration (fruits and vegetables)
Evaporative cooling
• Nighttime cooling
• High altitude cooling
• Underground storage 
Post harvest pests & diseases of selected commodities
Disease symptoms and control measures 

Food processing background
Definition and importance of food processing
• Need for food processing
• Importance of food processing for rural development

Food preservation principles and processes and fruit and vegetable products
Processing equipments and machinery
• Manufacturing processes
• Blanching (water and steam)
• Preservation by heat (canning)
• Preservation by refrigeration and freezing
• Preservation by bottling
• Pickling
• Preservation by removal of water (drying, freeze drying, concentration etc)
• Preservation by fermentation
• Preservation by addition of chemicals (syrup, salting etc)
• Deep frying technology
• Vegetable and fruit juice production
• Crystallization and candying

Basic microbiological and other types of hazards
• Moulds and yeasts
• Foreign matter
• Metals
• Glass
• Stones and other solids
• Chemicals and tainting 
Food packaging
• Packaging materials and their properties
     Glass
     Paper and paper based 
     Metal
     Plastics
     Laminates and metalized films
     Packaging specifications, packaging systems and equipments

Quality assurance and Control Operations
• Philosophy of control and assurance
• Quality Aspects of the manufacturing Sequence (Raw material, preparation of raw materials, blending, mixing, processing, cross-contamination, packaging, labeling, storage and distribution)
• HACCP as a quality control tool
• Legislative consideration (Bhutanese Food Laws)
• Hygiene (personal hygiene, factory structure, food machinery, etc)
Food factory design and operations
• Factory design and construction
• Design principles and infrastructure

 Readings & Additional Readings

1. Chakraverty A., 1997. Post Harvest Technology of Cereals, Pulses and Oilseeds. New Delhi: Oxford and IBH Publishing Co.

2. Dasgupta M.K., et al., 1989. Post harvest pathology of perishables. (Publishers unknown).

3. FAO Rome, 1989. Prevention of post-harvest food losses. Fruits, vegetables and root crops.

4. FAO., 1986. Improvement of Post harvest fresh fruits and vegetables handling. A Manual

5. FAO., 1995. Fruit and vegetable processing. Agriculture services bulletin No. 119

6. FAO., 1980. Handling and storage of food grains in tropical and subtropical areas.

7. Kader A.A., et al., 1985. Post Harvest Technology of Horticultural Crops. Cooperative Extension University of California, Special Publication 3311

8. Mitra S.K., 1997. Post Harvest physiology and storage of tropical and subtropical fruits. (Publishers unknown).

9. Pandey. P.H., 1998. Principles and Practices of Post Harvest Technology. New Delhi: Kalyani Publishers

10. Wills et al., 1989. Post Harvest. An Introduction to the physiology and handling of Fruits and vegetables. (Publishers unknown).

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