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2. Packaging and post-harvest losses
Post-harvest losses are losses occurring in the period between harvesting and consumption. The term 'losses' in the context of this manual is used in a wider sense, including all types of losses for the farmer, trader and consumer (e.g. weight loss, quality loss, financial loss, loss of goodwill, loss of marketing opportunities, loss of nutritional value, etc.).
FIG.1.Packaging and post-harvest losses
The distribution system for fresh produce in the Eastern Caribbean is complex. The movement of the produce from the farm to the consumer consists of many handling steps, uses low technology and is in the hands of many small traders. These factors, amongst others and combined with the high perishability of fresh produce, are contributing to high spoilage and unnecessary loss of produce.
Post-harvest losses are generally classified according to their primary causal agent. Frequently a post-harvest loss is a result of multiple causes and a succession of malpractices along the marketing chain.
2.1. Direct causes of post-harvest losses
Losses caused by mechanical injuries include cuts, bruises, abrasions and punctures and can be categorised into four major types of injuries.
a. Impact injuries, resulting from:
Loading and unloading is mostly done by hand, whereby crates are thrown into the pick-up, on board and into the hold.
Proper, rigid packages possibly with cushioning of each item within the package can reduce these impact losses
b. Vibration or abrasion injuries result when produce is able to move within a container because of:
FIG.1. Transmission vibration.
Fields in isolated hilly areas cannot always be reached by vehicles, so that produce has to be carried from the field to the road or track, which are often in a bad condition. Trucks and pick-ups used on these roads are also often in a bad condition. Tight filling of the crates can decrease the vibration of produce within the boxes and consequently reduce the injury. If the box is not completely filled with produce, it is suggested to use for instance shredded paper to tight-fill the box. Over-tight filling can lead to compression injury.
c. Compression injuries are caused by improper packing and inadequate package performance resulting from:
A high stack of (weak) crates or baskets leads to bulging and consequently to compression of the produce inside.
Rain or sea water can weaken the strength of carton boxes resulting in more compression injuries on the produce.
d. Puncturing injuries resulting from:
Baskets and old wooden crates and some of the plastic crates often have sharp edges which can easily damage the produce. Rigid crates with proper grips can reduce the incidence of puncturing.
2.1.2. Physical and environmental factors
Physical and environmental losses include the various responses of produce to excessive or insufficient heat, cold, gases or humidity.
Proper packaging is required to allow ventilation and heat exchange to maintain proper temperature level, to reduce the air and gas exchange (oxygen, carbon dioxide, ethylene) and to minimise water loss.
Holes in cartons should be at least five percent of the total box surface to allow for ventilation. Consumer packages slow the respiration rate by maintaining low oxygen and high carbondioxyde levels, protect the produce from ethylene and odour absorption and reduce the waterlogs.
2.1.3. Biological and microbiological losses
Biological and microbiological losses refer to the consumption of or damage to produce by insects, birds, rodents, bacteria, etc. Correct packaging, stacking and storing can reduce the incidence of this type of losses.
FIG.1. Biological and microbiological losses
2.1.4. (Bio-)chemical and physiological losses
Chemical and biochemical losses include undesirable reactions between chemical compounds and contamination with harmful substances such as certain pesticides. Treating the timber for the wooden crates incorrectly may influence the quality of the produce.
FIG.2. (Bio-)chemical and physiological losses
An example of losses due to physiological reactions is the sprouting of tubers.
2.2. Indirect causes of post-harvest losses
Indirect or secondary causes of post-harvest losses are losses due to external factors. Packaging can improve marketability and handling, thus decreasing losses.
Some indirect causes of post-harvest losses are:
a. Consumers' demand.
Promotional campaigns for local produce could include nice looking packaging material.
b. Inadequate marketing systems.
The large number of people involved in marketing of produce regionally contributes to greater losses since every person is responsible for a step in the marketing chain, often resulting in delayed marketing of produce. Suitable, uniform packaging with control of the content could speed up the flow of produce through the marketing channels.
d. Facilities.
Limited access exists to facilities such as stores, coldrooms, drying and curing rooms. Improved packaging will contribute to more efficient handling in and use of these facilities. More efficient use of these facilities will reduce the cost and thus decrease the price of the produce.
Transport of fresh produce in the Eastern Caribbean is not adequate and rather costly. In general, small pickups are used to transport produce from the farm to the port and wooden schooners are used for the transport between the islands. Produce is stowed up to three meters high in the hold without any physical protection. Deck cargo is either not protected against sun, rain or sea water, or is completely sealed in canvas preventing an airflow and suffocating the produce.
As long as small pickups and wooden schooners are used for transport standardised packaging cannot be introduced successfully.
e. Policy changes (e.g. agricultural diversification, quality standards, price policy).
Change of supply can be caused by for example seasonality, large imports or by Government policies like the ban Barbados placed on imports of mangoes from Dominica and St. Lucia due to mango seedweevil pest.
Government rules can force a trader to use special type of packaging such as carton boxes required for the French speaking islands.
f. Lack of training and awareness among people involved in the marketing system.
g. Underdeveloped infrastructure (roads, harbour facilities).
h. Cost of transport.
The inter-island freight cost is paid per unit, whether it is a box, crate or basket. These units are made as large as possible and packed as full as possible in order to save on transport costs. As a result product losses are high and crates are too heavy and too large to be carried by one person.
i. Unreliable supplies of packaging or high cost of packaging.
FIG.1. Indirect causes of post-harvest losses
