Consumers have been advised to inspect dark-stained yams carefully before cooking to avoid eating spoiled tubers that could pose health risks.
The Lagos State All Farmers Association of Nigeria (AFAN) and a public health expert gave the advice in separate interviews with the News Agency of Nigeria (NAN) on Sunday in Lagos.
They said that while some discolouration might be harmless, soft black patches, unpleasant odours and visible mould could indicate decay.
The stakeholders attributed yam discolouration to factors including fertiliser use, rodent attacks, accidental cuts during weeding and possible microbial contamination.
The Lagos State AFAN Chairman, Mr Sakin Agbayewa, said the dark colour could be linked to the type of fertiliser used during cultivation.
Agbayewa identified fertiliser application, rodent attacks and accidental injuries to tubers during weeding as three factors that could affect yam quality.
He explained that rodents sometimes attacked yam tubers planted in heaps, eating parts of them without farmers noticing.
According to him, farmers sometimes covered holes in yam heaps with soil without realising that rodents might have damaged the tubers.
Agbayewa said the damaged tubers could subsequently decay as they matured, affecting their quality. He also identified accidental cuts from cutlasses during weeding as another possible cause of deterioration.
He explained that farmers could unknowingly injure yam tubers while clearing weeds, exposing the affected areas to decay. Agbayewa, however, noted that the variety of yam cultivated could also influence its appearance.
Also speaking, a public health expert, Prof. Tanimola Akande, said the safety of dark-stained yam depended on the cause and nature of the discolouration.
Akande explained that yam that darkened naturally after exposure to air might remain safe for consumption if it showed no signs of spoilage.
He, however, warned that soft black patches, unpleasant odours and visible mould could indicate rotting caused by bacterial or fungal activity.
The public health expert said consuming rotten yam could expose people to harmful microorganisms or toxins, potentially causing stomach cramps, nausea, vomiting, fever and diarrhoea. He advised consumers to avoid eating yam showing signs of decay and to inspect tubers carefully before cooking.
Akande stressed the importance of distinguishing between natural darkening and discolouration associated with spoilage to reduce food safety risks.
