Chinese history is replete with records of extravagant dining. Even today, a celebration may involve at least 20 dishes with many of the main delicacies deep fried. Beijing’s extension of a ban on hotel weddings and parties therefore has tough implications for the world’s palm oil producers.

An unrelenting zero Covid-19 policy in China is one reason imports of palm oil, the world’s most widely consumed vegetable oil, have plunged. June import volumes fell more than 80 per cent compared with the previous year — the lowest half-year on record.

That is a problem for palm oil producers in south-east Asia. China has long been the world’s second biggest importer after India. It buys nearly all its supply from countries such as Indonesia and Malaysia, where nearly 90 per cent of the world’s palm oil is produced.

Palm oil prices hit a historic high earlier this year yielding a windfall for producers and traders. Palm oil company Wilmar posted a record net profit of $1.9bn in the year to December. Shares of Singapore-listed Wilmar and peer Golden Agri Resources gained more than 75 per cent in the year to last year’s peak.

In April, Indonesia responded to a domestic shortage with an export ban. This pushed prices up further, with the futures price for a tonne of Malaysian palm oil peaking at $1,730.

The ban has been reversed but at the cost of customers buying other edible oils elsewhere. Combined with falling Chinese demand, the result has been a glut. This will worsen as Indonesia eases export controls.

Prices have dropped to under $900 a tonne. Producers have lost a rare opportunity to cash in and improve historically low operating margins. These have languished at about 4 per cent for Wilmar for more than a decade. The shares trade at 10 times forward earnings, according to S&P.

Higher margins would allow the industry to invest in diversification. Palm oil production contributes heftily to carbon emissions and biodiversity losses. Sustainable production schemes merit scepticism. If China regains its taste for palm oil, the developed world may have already lost it.