What is Post harvest Technology?
Post harvest technology involves in harvesting, handling, storing, moving the produce to reduce losses and to keep them fresh up to the market.
It’s of utmost important to maintain the freshness or to minimize the deterioration of products from harvesting, marketing and to the time they are consumed.
The increase in vegetable and fruit production don’t guarantee sufficient supply of good quality product for consumer to eat and the grower to sell, due to post harvest losses.
The percentage losses in vegetable production is from 28 – 42% of the annual production ( under Philippine condition) due to lack of post harvest facilities and technology.
This is because the Philippines is still lagging behind in post harvest technologies as compared to the developed countries.
Causes of Post harvest losses
1) Technological – Post harvest losses covers the following causes…
- Decay or rotting – Vegetable easily decay or rot when not properly handled, especially the leafy ones. Fruits last a little longer but they easily rot as well.
- Yellowing – Yellowing mostly happens to leafy vegetables. For fruits yellowing is a sign of ripening and later decay.
- Wilting – This is common to leafy vegetables.
- Softening – Softening is mostly prevalent to fruits and some leafy crops.
- Sprouting – Some root vegetables when stored longer tends to sprout (e.g. carrots, potato, sweet potato, onion, garlic, etc.)
2) Non-technological – Post harvest losses mostly occurs when there is lack in transportation and storage facilities causing the delay of the harvested products.
Non-technological losses covers the following factors…
- Transportation – Lack of transportation is one factor that causes post harvest losses. Before you venture into vegetable production you should provide this very important equipment in your priority list.
- Storage – Storage facilities plays a vital role for a success in vegetable endeavor. If transportation facilities is vital, storage area is also important. In fact, if I’m to decide, I would place this factor as my number one priority.
- Adverse weather condition – Changing weather condition greatly affects your cropping pattern. Study the condition in your area, what particular crop or crops that thrives best to a particular weather condition.
- Inefficiency of distribution – If your distribution channel is inefficient crop damage will be severe. Therefore, make your strategy feasible so that your product could reach to the buyers fresh.
- Lack of market demand – Consider surveying the market if the crop you’ll plant is needed or in demand. This is one factor that causes crop losses because nobody buys your product.
3) Physiological damage – Crop damage is caused due to changes in texture, flavor and aroma.
4) Mechanical damage – Crop losses due to rough and careless picking, packing, loading or unloading. The damage maybe in the form of cuts, punctures, cracks, splits, changes in forms and shape or partial or fully separation of the outer covering.
5) Insect damage – Damages caused by insect occurs at storage or directly in the field before harvest. You’ve to control immediately those insect found in the field prior to harvesting or in your storage area. Your storage room should be disinfected before placing your harvested products.
Basis of Post harvest Technology
1) Vegetables are perishable in nature – Though they’re already harvested and not in the soil anymore, they’re still living thing. They still undergo all the biological processes connected with life.
When harvested, the intake of energy through respiration and manufacture foods through photosynthetic process is cut and there’s no replacement for the lost reserves.
The faster it respires, the faster it rots. High stored food delayed rotting.
Vegetables contains 80 – 95 water. This is lost to the atmosphere through transpiration especially during dry and hot months.
2) Differences in Morphology, Structure and Chemical Composition
The changes depends on what morphological parts the vegetable is…
- Leafy vegetable – The leaves wilt and turn yellow.
- Fruit vegetables – Ripens eventually become over ripe.
- Flower vegetables – The flowers opens.
- Modified stem – Produces new buds and sprouts.
Changes on structural differences of each morphological parts…
- Leafy vegetables – Have bigger and more stomata on upper and lower surface, therefore have faster respiration and transpiration.
- Fruits, roots, tubers, and bulbs – Have reserve surface areas and few or no stomata but have few lenticels.
3) Response of Vegetables to Environment – Respiration and transpiration of vegetable changes in response to the environment…
- Temperature – The most critical environmental factors that influences the deterioration rate of vegetables. Decrease in temperature decreases respiration, transpirations, microbial activities and insect growth.
- Relative humidity – The ratio or content of water vapor in the air.
- Gases in the atmosphere – Ideal content of air is 78% Nitrogen, 21% Oxygen, and 0.03% Carbon dioxide.
- Microorganisms and insects – Vegetables serves as food for microorganisms and insects. The more we keep away vegetables from them, the longer we can keep vegetables.
How to Reduce Vegetable Losses
1) Start with good quality seeds or planting materials – You’ve to look into the characteristics of your stock in relation to its size, shape, color, texture, weight and nutrient content.
- Influence of Environmental Condition – The quality of your vegetable at or after harvest is affected by temperature, light, rainfall and other environmental factors.
- Effects of Cultural Management – You should start your field preparation exactly right. This includes seedbed preparation along with water management, weeding, fertilization, control of pests and diseases. If you neglect these cultural management practices, the quality of your product will be greatly affected.
2) Avoid Physical Damage – Physical damages starts during harvesting up to sorting, cleaning, transport from the field to the storage area and down to the market.
Strictly follow the correct method of handling your product to avoid physical damage at serious level.
3) Control Environmental Factors – Using low temperature (Refrigerator) during transport or storage and application of chemical to control post harvest decay is one strategy to avoid crop damage.
You can apply the following strategies…
- Temperature management – Avoid high temperature to lengthen the life span of your vegetables.
The use of refrigerator is the most effective way of lowering temperature.
In the absence of Refrigerated facilities, you can apply the following methods to minimize crop losses…
1) Harvest as early or as late in the day as possible.
2) Avoid exposing vegetables to direct sunlight at anytime.
3) Put sufficient ventilation during transport.
4) Use white colored canvass for covering vegetables.
5) Travel as early or at night if possible.
- Relative Humidity Management – You’ve to increase the relative humidity to 85%.
Methods of increasing Relative Humidity…
1) Wet the floor of the area where vegetables are kept.
2) Introduce a fine mist of water or steam into the ventilating fan.
3) In a small room keep open containers filled with water.
4) Use evaporative cooling system.
- Control of Gases in the Environment – Decrease in oxygen and increase in carbon dioxide makes transport and storage in low temperature. The use of polyethylene bag allows the accumulation of carbon dioxide and depletion of oxygen inside the bag with few holes to allow ventilation. Ethylene use should be avoided except where ripening of fruits is involved.
How to Avoid Ethylene Effect
- Ensure good ventilation to dilute the concentration of ethylene – Ventilation is vital during storage and transport so that ethylene accumulation can be avoided.
- Don’t store ripening fruits with fresh vegetables in the same room – Separate fruit vegetables from the leafy ones. Ethylene is for ripening purposes only. If it would combine with leafy vegetables the leaves becomes yellowish – not anymore good or market.
- Proper handling during transport and storage should be practiced at all times – Proper handling means,you should apply the correct storage and transport procedure to insure that the vegetables are safe and free from any damage.
- Sort products and separate diseased and injured vegetables – It is important that you should separate the diseased and injured products. Ones they’re not sorted, the tendency is the spread of the diseases would affect the other that are in good conditions. Avoid keeping vegetables in enclosed areas where there is smoke – You’ve to do away your products in enclosed areas where there’s no ventilation especially when there’s smoke around the area – this will affect the quality of the products.
How to Reduce Microorganisms Multiplication
- Make the container, vehicle, room clean before placing the products – This is self explanatory, clean surroundings is always the ideal place for storing anything.
- Handle vegetables carefully to avoid injury – Carefully handle your products with care to avoid crop injury. Injured areas are the ones where bacteria or virus enters which may cause the deterioration of the products.
- Avoid hot and moist condition – Hot and moist condition attracts some deadly microorganisms which is there ideal place to live and multiply. You should make sure that the area is dry and there is a free circulation of air all around.
- Sort the products and separate diseased vegetables – As I explained in number 4 above, you’ve to separate the diseased and injured products to avoid contamination to the other crops that are good.
- If vegetables are likely to be disinfected, use Alum or Lime – If you’re to store or transport your products, it’s best to disinfect them with Alum or Lime to lengthen their life span. This is mostly applicable to leafy vegetables where their shelf-life is only short.
- Cure root and bulb crops before storage and transport up to 20 – 35 °C – Curing your products increases their shelf-life especially when you store them for a longer time or transporting in a long distance.
Cris Ramasasa, Freelance writer, writes about home gardening and Internet marketing tips. You can get a copy of his latest ebook “How to get started in Flower Gardening”and “Vegetable Gardening made Easy” and lots of tips, Free articles, and bonuses at: www.crisramasasa.com