Why people toss out more organic potatoes

"Losses at the end of the chain are the worst because, at this stage, the most energy has been put into the product. The most sensible thing is therefore to minimize household waste," says Christian Willersinn. (Credit: Laurence Vagner/Flickr)

People throw out more organic potatoes than regular ones, according to a food waste study conducted in Switzerland.

About 660 pounds of perfectly good food ends up in the trash per Swiss person each year, report researchers. And on the way from field to fork, more than half of the potato harvest goes to waste.

The study breaks down the losses of this staple food along the entire supply chain. “With this study, we aim to deepen the discussion relating to food waste by looking at a single product,” says lead author Christian Willersinn, a doctoral student at ETH Zurich. The study appears in the journal Waste Management.

Willersinn and colleagues used data from quality assessment of individual tubers, surveyed wholesalers and retailers, and carried out a written survey of 2,000 households. In addition, 87 people kept a diary for 30 days, in which they recorded their exact potato consumption and exactly how much of the originally purchased quantity, including preparation waste, ended up in their bins.

From the field to the home, 53 percent of conventionally produced table potatoes go to waste, and this figure rises to 55 percent for those produced organically. For processing potatoes, the figures are lower: 41 percent of organic potatoes are discarded, compared to 46 percent of those from conventional production.

The higher waste proportion for conventionally farmed processing potatoes is connected to the overproduction of this crop, which barely ever occurs with organic farming.

Picky consumers and ugly potatoes

Waste is greater for organically farmed table potatoes because these fail to satisfy the high quality standards more often than conventional ones. “After all, consumers have the same expectations of quality and appearance for organic production as they do for conventional.”

Losses occur at all stages of the supply chain: up to a quarter of the table potato harvest falls by the wayside even at the producer stage. Wholesalers reject an additional 12 to 24 percent during sorting. Just one to three percent fall between the cracks at retailers, and a further 15 percent go to waste in households.

Although private households account for a relatively small proportion of potato waste, Willersinn says their contribution has the most impact: in private homes, most of the unused potatoes end up in the bin bag or on the compost heap. Producers, traders, and processors, on the other hand, recycle the vast majority of waste into animal fodder or, to a lesser extent, into feedstock for biogas plants.

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Consumer health protection also leads to waste: producers reject one in three potatoes after harvest because they are rotten or green and could therefore be harmful to health.

Wireworms, i.e. the larvae of click beetles, have also eaten holes into many potatoes, although they would still be edible. Likewise, misshapen or deformed potatoes would be edible but, just like “worm-eaten” potatoes, are fed to animals for aesthetic reasons.

New habits

In order to reduce potato waste, therefore, the researcher suggests taking action on the producer side first and foremost; for example, by using suitable cultivation methods such as crop rotation to minimize infestation, by protecting plants against wireworms, and by breeding new, more-robust varieties of potatoes.

Shrinking the mountain of waste would also require revised quality requirements, so that misshapen or scabby potatoes could make it onto the shelves. This could reduce losses of conventional fresh potatoes by four percent and organic table potatoes by three percent.

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However, he says that wholesalers and retailers take a critical view of scabby potatoes, as scab can be transmitted to healthy specimens. “This would mean that waste would occur at the end-consumer stage, instead of at the producer and trader level, because consumers have different quality expectations,” Willersinn adds.

He says the eco-balance is at its worst when consumers throw potatoes in the bin. “Losses at the end of the chain are the worst because, at this stage, the most energy has been put into the product. The most sensible thing is therefore to minimize household waste,” Willersinn emphasizes.

In addition, consumers need to reconsider their preferences and their buying and eating habits, he says, noting that, according to the household survey, older people throw out less than young people.

Source: ETH Zurich