In Johannesburg’s buzzy student enclave of Braamfontein, the rising price of potatoes is undermining its communal eating culture as people snack solo to save money.

Chips, as fried potatoes are called here, are a staple in South Africa, often simply eaten with bread or inside a kota – a hollowed out quarter loaf that’s then generously stuffed with layers of fillings like cheese, egg, sausage and tomato ketchup.

For a 10 kilo (22 pound) bag of potatoes, Tlou Boshomane, who owns a shop selling snacks across from the University of Witwatersrand, must now pay 140 to 150 rand ($7.5-$8) – twice the price of a year ago.

Boshomane was forced to slim portion sizes to protect his profit margin.

“It’s more about re-looking at the menu, re-engineering portions and pricing,” he said, adding that he’s seeing an impact of the dining habits of his customers, with fewer people buying to share. “The more prices go higher, culture changes also, of eating, of consuming,” he said.

South Africa’s annual inflation rate has declined from a peak of 7.8% last year to 5.4% in September. But food inflation remains high at 8% and the central bank has repeatedly warned of the threats posed by persistent price pressures from the sustenance.

Poor Pinched

A burden felt most by poorer households — who spend a larger share of their income on feeding their families — making the anxiety over the high cost of living a potent part of the political conversation ahead of next year’s general election.

In Bloomberg’s Shisa Nyama Index, which tracks the prices of key ingredients in a traditional barbecue consumed in South African townships, the cost of potatoes surged 40% month-on-month in October.

Crunching data from the Pietermaritzburg Economic Justice and Dignity group, the gauge includes potatoes, cooking oil, corn meal, carrots, tomatoes, frozen chicken, beef and wors — a tasty sausage made from ground meat offcuts.

The overall index rose 17% last month, up from 12.5% in September. South African consumer price data for October will be released on Nov. 22.

To compile its survey, the group tracks the prices of 44 food items on the shelves of 47 supermarkets and 32 butcheries that target the low-income market in the greater areas of Johannesburg, Durban, Cape Town, Pietermaritzburg, Springbok in the far northwest and the far north-eastern town of Mtubatuba.

Usiphile Ndimande, a student who usually eats with friends, has considered lunching on his own but worries he’ll come up short either way.

“If you go it alone it’s going to hurt financially,” Ndimande said. “It’s better if there’s more of us. But if you do, you don’t get full. You lose both ways.”

This story was produced with the assistance of Bloomberg Automation.