- LISA KITINOJA is the founder of Postharvest Education Foundation (PEF), a non-profit organisation based in the US, to provides motivation, training and mentoring for young postharvest professionals around the world. She has been involved as a private consultant in international horticultural development work since the 1980s and has been specializing in postharvest technology, food loss reduction and the extension of information on small-scale postharvest handling practices since 1992 as Principal Consultant of the firm Extension Systems International. She provides advice and technical assistance for several international projects in Rwanda, Uganda, Ethiopia, and participates in global policy development efforts undertaken by FAO and others. She shares her thoughts with AAA, NATHANIEL AKHIGBE. Excerpt:
What constitutes postharvest losses, in your experience and what investment can African governments make to check it?
In my work as a postharvest specialist, I have identified many types of postharvest losses. All of these postharvest losses can be addressed via training of workers, capacity building for extension service and small business development for growers, traders and marketers, and investment in SMEs.
Physical losses occur due to rough handling, damage during harvesting, use of improper containers (such as too large, or too flimsy to protect the product when stacked), use of poor quality storage (if it is too hot, too dry, or pest-infested) or exposing harvested produce to sun, heat, rain or dust during handling, processing or marketing. Lack of access to markets can cause growers to allow produce to go un-harvested (this is happening now in 2020 as Covid-19 disrupts food supply chains) or lead to dumping or composting edible produce when no buyer can be found. Physical losses result in weight loss, water loss, decay or consumption by pests.
Quality losses appear as changes in colour (such as yellowing of green vegetables or browning of fruit after an injury), appearance, texture or flavour, and can be due to water loss (shrivelling, wilting or dulling of surface shine), exposure to dust/debris, sunlight and heat, or attack by pests (fungi, insects or rodents). Water loss increases if produce is damaged or exposed to high temperatures or low relative humidity conditions.
Nutritional losses begin to occur immediately after fruits and vegetables are harvested. Losses of water-soluble vitamins increase with time and with improper temperature management. Loss of vitamin C increases with any conditions that allow water loss. Losses of calories, phytonutrients, vitamins and minerals also occur when produce is damaged and discarded before consumption.
Food safety losses are related to both physical and quality losses, since GAP protocols require field sanitation, use of clean water for washing, clean containers for packing, use of appropriate pesticides and sanitizing agents, and labour following safe hygiene practices. If produce is contaminated by physical items (wood, metal or plastic debris), chemical substances (incorrect sanitation solutions or pesticide residues) or biological matter (foodborne pathogens such as bacteria or viruses, or toxins produced by biological contaminants), then damage can lead both to quality losses with associated loss of market value, and sorting out for physical losses.
Market value losses are the end result of PHLs when produce deteriorates in appearance or overall quality (leading to a lower offered price per kg), or when produce is sorted out and discarded so there is less volume available to sell. Nutrient-dense foods may be more highly valued by some buyers (for example hospitals, health food advocates, or tourists), and high-value horticultural crops are often produced for export, which requires improved postharvest handling, documented food safety, and serious investment in the cold chain.
What are the main reasons for postharvest losses, particularly in Africa?
Postharvest losses can be due to poor planning (everyone growing the same crop at the same time), rough handling (throwing, dropping or crushing the produce), use of poor quality packages and containers (large sacks, baskets or roughly made crates) and lack of temperature management. Harvested foods, including fresh produce, fish, dairy and meat products, need cooling and temperature management to protect the foods from rapid deterioration.
Postharvest losses in Africa are estimated to be between 30% and 50%. If this is not checked, what negative impacts will this have on food security, job and wealth creation in Africa?
I prefer to talk about the positive impacts that reducing food losses can have on Africa’s wealth creation, jobs and food security. Consider how losing 30 to 50% of the produced food before it can be consumed by humans is a source of great economic opportunities. Capturing these losses and converting them into more nutritious foods (for people to eat, for animal feeds or for composting and conversion to soil amendments) offers many small business opportunities for growers, traders, processors, storage operators, and transporters and marketers. The lost food (now allowed to decay until it has zero market value, or which can even cost money if it has to be removed and transported to landfills) can be used to create new “recycled” or “upscaled” food products and provide benefits such as reduced greenhouse gas production, sources for making organic fertilizers and inputs for improved animal feeds. It is possible to imagine a world with sustainable food systems where there is 100% utilization of all the food that is produced.