Want to keep your mangoes fresh? Wax them

In a few weeks’ time, the sight of rotting mangoes on farms will once again start haunting us. Reason? It is another mango harvesting season and the various mango-producing counties will once again be awash with post-harvest losses.

Mangoes are a seasonal crop with high and low seasons. The season starts in December and peaks from January to February. Post-harvest experts estimate that 40 to 50 percent of the fruits and vegetables grown in Kenya are lost. In Kenya, 80 percent of the mangoes are eaten while still fresh, hence the need to increase their shelf life.

This scenario could be averted through the use of simple technologies that mango farmers can use on the farm to curb the loss of agricultural produce.

Waxing

Mr. Benson Maina, a plant scientist thinks shelf life of perishable fruits can be extended by coating them with wax. Mango waxing technology, he explains, slows down the diffusion of water and gas from the fruits.

• This therefore reduces their water loss and respiration, to prolong their shelf-life. It is a special kind of food grade wax, which is safe for food preservation.

Mr Maina says the wax replaces the natural wax found on mature fruits and which is often washed off or removed during handling.

“A lot of mangoes go to waste, especially when there is a surplus. However, with low-cost postharvest technologies such as fruit waxing the losses can be averted,” says Mr Maina.

“Poor storage and diseases are the major causes of post-harvest loss in the mango value chain. There are key processes that occur when fruits are harvested.

• such as loss of cuticle during the washing and rubbing against each other,
• water loss and respiration, which leads to food reserves in the fruit being broken down by oxidation.

And since respiration and transpirational water loss contribute to the deterioration of fruits and vegetables after harvest, there is a need to safeguard farmers’ produce using innovative technologies.

If farmers bought this artificial wax, it could help slow down the rate of oxidation and loss of water in the mango fruit.

Demonstrations of waxing

Since last year, Mr Maina has been in the laboratory testing the efficacy of mango waxing technology. He explains that the pilot phase at the Embu-based Karurumo Horticulture Self-help Group, which processes mangoes into various products, is causing excitement.

“Traditionally, people never waxed mangoes, but did it for other fruits such as apples, oranges, and avocadoes. But after the research I realised I could use the same principle in mangoes,” says Mr Maina.

“During the demonstrations, treated and untreated fruits were left with farmers for two weeks and an assessment was done to check the impact of waxing. The waxed performed way better than the untreated ones.”

The wax used for food preservation is not cancerous and is developed specifically for food preservation.

The project is seeking certification from local authorities before its rollout. However, says the researcher, “the wax understudies are used elsewhere. And is already accepted by the European Union under INS 471”. The waxing technology increases the shelf life of mangoes to around 28 days.

There are two types, shellac and deco mango wax. His extensive laboratory research has propelled him to conduct trials between two farmer groups with an average of 50 farmers in Embu County.

So how does the waxing technology work?

“Respiration and transpiration are the major factors contributing to the postharvest deterioration in fruits. Mangoes have about 70 per cent water which is lost to its surroundings due to water pressure deficit.”

Coating fruits with wax compensates for the lost natural wax. And provides a barrier to water and gas diffusion by reducing the number and/or the size of lenticels.

This leads to water saturation inside the fruit, reducing oxygen diffusion and carbon dioxide leaving the fruit, thereby slowing down transpiration water loss and respiration. To prolong their shelf-life. It is a special kind of food grade wax, which is safe for food preservation.

“A lot of mangoes go to waste, especially when there is a glut. However, with low-cost postharvest technologies such as fruit waxing the losses can be averted,” says Mr Maina.

If farmers bought this artificial wax, it could help slow down the rate of oxidation and loss of water in the mango fruit. Since last year, Mr Maina has been in the laboratory testing the efficacy of mango waxing technology.

He explains that the pilot phase at the Embu-based Karurumo Horticulture Self-help Group, which processes mangoes into various products, is causing excitement.

“Traditionally, people never waxed mangoes, but did it for other fruits such as apples, oranges, and avocadoes. But after the research I realised I could use the same principle in mangoes,” says Mr Maina.

“During the demonstrations, treated and untreated fruits were left with farmers for two weeks and an assessment was done to check the impact of waxing. The waxed performed way better than the untreated ones.” and respiration.

With consumers in urban markets or out of the country in need of fresh fruits and vegetables, smallholder farmers, who form part of the value chain, need ways to supply. Postharvest technologies such as Controlled

Atmosphere are very expensive and out of reach for many smallholders. Coating mangoes with wax is a cheap, easy to access and use postharvest handling technology.

Most of the fruits exported such as avocados are coated with wax to ensure they stay in an unripe state until they reach the consumer.

“Consumers almost dictate what goes into their food or how that food is grown. But the same consumers need fresh produce,” says Mr Maina. Waxing technology helps to reduce logistical costs for traders exporting fruits.

“Mangoes, especially from Kenya, are transported by air, making it very expensive. Delayed ripening by waxing could help mangoes stay for 28 days in good condition. Therefore, sea freight could be adopted, reducing the transport costs incurred by traders.”

The added wax also helps to protect the fruit from bruises and adds gloss to the fruit, says Mr Maina. Dr Jane Ambuko, a post-harvest expert at the Department of Plant Science and Crop Protection, University of Nairobi, says appropriate technologies are vital in extending the shelf life of fruits and vegetables.

To realise full potential, Dr Ambuko advises, technologies such as waxing must be used together with easily-affordable cold storage systems to ensure better returns for farmers.

She notes that off-season crops are money spinners for farmers, hence the need for better post-harvest management. “Lack of access to affordable and easy-to-fabricate post-harvest technologies for handling or storing at the farm level, is to blame for such losses,” she says.

The researcher’s next stage is to promote the technology among mango exporters. “Farmers will be able to get the wax in small quantities, which will be affordable. But, as of now, I can’t be able to say at how much until we go full scale,” says Mr Maina.

“We are now moving to the stage of conducting demos for mango export companies. The long and short of things is, actually, we can use waxing technology as alternative post-harvest loss management for handling mangoes,” he explains.

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