Training manual for postharvest handling of horticultural crops in Rwanda


This 146 page training manual was published in June of 2018 by the Horticulture Innovation Lab’s Reducing Postharvest Losses in Rwanda project.  Christine Mukantwali, Eric Kabayiza, Hilda Vasanthakaalam, Serge Ndayitabi, Jean-Paul Hategekimana, Gerardine Nyirahaganyamunsi, Solange Musanase, Vincent Gasasira, Aloys Hakizimana, Sharon Cyatengwa, Alfred Nsigaye, and Jean-Claude Nyamatsi contributed to the manual.  This training manual was developed to build capacities and knowledge on how to protect the quality of the produce, and is intended for frequent use to train workers in the horticulture value chain.

In Rwanda, agriculture the major source of food security and cash income for majority of the rural population.  Up to one million rural households grow horticultural commodities, principally for home use and sale.  Horticultural crops are highly perishable and nutrient dense.  The three main objectives of applying postharvest technology to harvested fruits and vegetables are

  1. To maintain quality (appearance, texture, flavor and nutritive value),
  2. Ensure food safety (physical, chemical and biological), and
  3. Reduce losses between harvest and consumption.

This manual will assist the identification and utilization of scale-appropriate, cost-effective postharvest technologies for handling fresh horticultural produce to:

  • Reduce postharvest losses due to water and weight loss, decay and physical damage
  • Maintain the quality of the produce (color, flavor, texture, appearance, nutritional value, etc.) and economic value during postharvest handling, storage and transport
  • Increase shelf life with proper temperature and relative humidity management
  • Assure food safety during fresh handling
  • Increase income by adopting postharvest technologies that are most profitable for small-scale operations.

The manual is broken down into nine modules. 

Module 1: Introduction to Postharvest Handling of Horticultural Crops

The module aims to instruct trainers how to carry out introductory session with farmers.  It begins by defining postharvest losses and food waste, before discussing levels of postharvest losses around with world and within Rwanda. 

Next, the different types of losses, the type of quality deterioration they cause on the produce, and the primary causes of postharvest losses by produce type.  Some types of produce, such as dried fruits and vegetables have very low perishability while others, such as strawberries or spinach, have very high perishability. 

Lastly, information is provided for those users who may be interested in learning more about export marketing.  This includes references relating to inspection services and standards. 

Module 2: Good Agricultural Practices (GAP)

Good Agriculture Practices influence the quality and quantity of the farmer’s produce. The implementation of Good Agriculture Practices will help the farmer to reduce physical, chemical and biological risks that may destroy the produce.

GAP begins with site selection, seed selection, organic and mineral fertilizer application, pest and disease control and irrigation. In this module the participants will cover Good Agriculture Practices related to soil, plant nutrition and crop protection, the GAP dos & don’ts, chemical and biological control.

The module aims to instruct the trainer the Best Practices for GAP to reduce postharvest losses in horticultural crops.  It should be accompanied by a visit to a nearby farm after completion of the theoretical section. 

Module 3: Harvesting Best Practices

Harvesting and rough handling at the farm directly affects market quality. Bruises and injuries show up as brown and black patches making the commodities unattractive. Injuries to the peel serve as avenues for microorganisms that lead to rotting and shorten storage life. Lack of knowledge about the principles of proper harvesting will result in a waste of vegetables and fruits. After all, harvest means an abrupt termination of life: in the field or human law, this would be called ‘murder’.

One of the most common mistakes growers make is to harvest fruit crops too early when they are under-ripe and have not yet developed their full flavor. Some vegetables, if overgrown, will be too fibrous or full of seeds that hinder good taste. With many horticultural crops, if you harvest all at once, you are sure to have many items that are either under-mature or over- mature. Using a maturity index as a standard will greatly reduce pre-sorting losses. For some crops this involves using a refractometer to measure soluble solids (mostly sugars) or a penetrometer to measure firmness.

The module aims to instruct participants the best harvesting practices. The session discusses maturity standards, use of maturity testing tools e.g. refractometer, firmness tester and maturity indices charts, harvesting practices, harvesting containers, harvesting tools and field packaging.

Module 4: Appropriate Postharvest Handling Practices

Postharvest is the final stage of production and any losses experienced at this point are more severe as they represent wastage of all resources involved during production. Packing house operations can be as simple as moving produce from the field into a shipping container or may include a variety of handling practices, from cleaning, waxing, sizing, and quality grading to color sorting. The choice of operations will often depend upon the buyer’s demands and on the market value of the produce.

In this module, participants will learn operations, tools and equipment that extend shelf life of harvested fresh produce (the use of shade, sorting, grading, packing house operations and curing for roots and tubers mainly of sweet potatoes and onions).  After this module, participants will be equipped with important postharvest handling techniques for horticultural produce from the field to the market. The participants have knowledge on importance of temperature management of harvested crops in extending their shelf life, and on equipment and tools used for extension of life and improving quality of harvested fresh produce.

Module 5: Appropriate Packing Containers

Packaging is defined as a mean or system by which a fresh produce or processed product will reach from the production center to the ultimate consumer in safe & sound condition at an affordable price.

If produce is packed for ease of handling, heavily waxed cartons, wooden crates or rigid plastic containers are preferable to bags or open baskets, since bags and baskets provide no protection to the produce when stacked.

Sometimes locally constructed containers can be strengthened or lined to provide added protection to produce. Waxed cartons, wooden crates and plastic containers, while more expensive, are reusable and can stand up to the high relative humidity found in the storage environment.

In this module, the participants will learn appropriate packing containers and disadvantages of using inappropriate ones hence reducing postharvest losses.  After completion the participants are aware of the use of recommended and appropriate packing materials and are ready to disseminate to farmers.

Module 6: Temperature and Relative Humidity Control

Temperature and relative humidity management are sometimes referred to as "Maintaining the Cold Chain" during postharvest handling and marketing. If produce is to be stored, it is important to begin with a high quality product. The containers must be well ventilated, strong enough to withstand stacking and capable of enduring handling, cooling and storage conditions (high humidity environment).

In general proper storage practices include:

  • temperature control,
  • relative humidity control,
  • air circulation and maintenance of space between containers for adequate ventilation,
  • Avoiding incompatible product mixes.

The goal of this module is that participants learn the importance of temperature and relative humidity in extending shelf life, and help maintain quality and nutritional value of the produce by considering the costs & economic benefits.  After, participants will be aware of recommended temperature and relative humidity for each produce and how to manage them.

Module 7: Transportation of Horticultural Crops

Temperature management is critical during long distance transport. Loads must be stacked to allow proper air circulation to carry away heat from the produce itself as well as incoming heat from the atmosphere and off the road. Transport vehicles should be well-insulated to maintain cool environments for pre-cooled commodities and well-ventilated to allow air movement through the produce.

During transport, produce must be stacked in ways that minimize damage, then braced and secured. An open-air vehicle can be loaded in such a way that allows air to pass through the load and provides some cooling of the produce as the vehicle moves. Also, traveling during the night and early morning can reduce the heat load on a vehicle that is transporting produce. Drivers of vehicles used for shipping produce must be trained in proper loading and handling of produce.

Mixed loads can be a serious concern when temperature optima are not compatible. For example, transporting chilling-sensitive fruits with commodities that require very low temperatures or ethylene-producing commodities with ethylene-sensitive commodities can cause serious damage to the loads. High-ethylene producers (such as ripe bananas, apples, etc.) can induce physiological disorders and/or undesirable changes in color, flavor and texture in ethylene-sensitive commodities (such as lettuce, cucumbers, carrots, potatoes, and sweet potatoes).

This module will raise the awareness of participants in the importance of appropriate ways of transportation for their produce.  After completion, participants will understand the effect of transport to the quality of the fresh horticultural produce.

Module 8: Small Scale Food Processing

Small-scale food processing is important worldwide. For individual processors, it is highly accessible as a start-up business, especially for producers that can readily diversify into processing to increase their income; and high added-value which enables them to earn an income from relatively small scale of production.

Small-scale food processing can create employment, increase food security and improve nutritional standards. It requires also assessing the market from primary and secondary processing, packaging and food safety.

Processing fruits and vegetables is intended to do two things:

  1. To preserve them by slowing down the natural processes of decay caused by micro- organisms and enzymes in the food, or other factors such as heat, moisture and sunlight.
  2. To change them into different foods, which are attractive and in demand by consumers. By doing this successfully, they can increase sales and earn an income.

The purpose of this module is to guide small-scale processors of fruits and vegetables in Rwanda to optimize their processing methods. Participants will learn Good Hygienic Practices (GHP) and protocols of Good Manufacturing Practices (GMP), and therefore build their technical capacity.  Participants will get basic skills in food processing such as drying, making pulp and juicing as well as other techniques of product extraction.

Module 9: Food Safety

Concerns about food safety when handling fresh fruits and vegetables have increased over the past decades. Food-borne disease outbreaks have been associated with tomatoes, leafy greens, and fresh herbs and cut fruits. Wholesale buyers and consumers are increasingly interested in the use of handling practices that will ensure food safety. It is the responsibility of growers and postharvest handlers to document their food safety practices in order to protect fresh produce from contamination. Retailers, such as large supermarket chains, are demanding compliance with food safety practices from their suppliers. It is nearly impossible to export produce to Europe or the U.S. without documenting its safe handling from the farm to the market.

Some general food safety practices are being promoted by universities, governmental agencies and private sector organizations around the world. For growers who want to export their produce to the European Community (EC), you should be aware that standards are being enforced by the retail produce industry to guide handling practices for growers and shippers (known as Global GAP). Key concepts are the implementation of GAP (Good Agricultural Practices) on the farm, in the packinghouse and during transport of all fresh produce, and HACCP (Hazard Analysis Critical Control Points) to document the safe handling of farm chemicals, pesticides, packaging materials, etc., especially for processed or fresh-cut produce.

This module trains participants on the causes and impact of unsafe food on human health and its relationship with production and postharvest handling.  The participants will learn the principles to reduce health risks of produce contamination.