Homer Simpson would not be amused. First, rising prices on malting barley threaten to send the cost of Duff (and other beers) up, and now raw material hikes spell bad news for his favourite snack - doughnuts.

The overall material cost for an average doughnut has gone up by 15% year-on-year. This may seem counter-intuitive at first - after all, the ingredients that make up the bulk of a doughnut’s volume are cheaper now than a year ago. For example, bread wheat - which accounts for about 40% of the total ingredients in a doughnut - is currently down 21% to £156/tonne, while frozen raspberries - used in doughnut fillings and accounting for about 16% of total ingredients - are down 7% year-on-year to £4,280/tonne.

But these falls are more than offset by hikes on other ingredients. The price of confectionery sugar - which makes up about 10% of a doughnut’s raw material volume - has risen by 54% to £670/tonne over the past year, largely because the EU’s Common Agricultural Policy reform has turned Europe into a sugar importer. Meanwhile, groundnut oil - which accounts for roughly 13% of doughnut raw materials - has gone up by 56% to £1,470/tonne, driven by poor US crops and rising demand in Asia. There have also been rises in the cost of milk, up 15% to £275/tonne, and eggs, up 73% to £1,120/tonne.

Manufacturers are trying to mitigate these increases by switching to cheaper ingredients. Groundnut oil is typically being replaced with rapeseed or palm oil, currently down by a respective 14% and 18% year-on-year. But alternatives are less easy to find for sugar and dairy products, leaving producers with little choice but to absorb higher costs - or pass them on.

Doughnuts are often sold on bogof deals, but it might be more difficult to persuade suppliers to run these kinds of offers in the year ahead. Some may even be tempted to make their doughnuts smaller or lighter. D’oh!