A year before, the proportion was 43.8%.

However, the drop also reflected a sharp fall-off in cane volumes processed, down 40% year on year at 15.75m tonnes – a decline of which Unica and other commentators have long cautioned, thanks to Centre South drought which has meant a speedy harvest, but of a low-yielding crop.

'Ambivalent investors'

Nonetheless, sugar futures for March stood 1.9% lower at 15.18 cents a pound in late deals in New York, within 0.20 cents of a contract low, in part thanks to Centre South cane and sugar production which, while lower year on year, has exceeded gloomy forecasts earlier in the year.

"Generally the consensus seems to be ambivalent to the curtains being drawn on this [Centre South crush] campaign," said Thomas Kujawa, co-head of the softs desk at Sucden Financial.

Green Pool noted last week that "as the Centre South Brazil harvest winds down, expectations for the final crop are moving higher", as the Australia-based consultancy raised its own estimate for full season cane volumes to 558m tonnes, and sugar output to 32m tonnes.

The International Sugar Organization said on Monday that while "damage caused by a severe drought earlier this year [has] started to become more apparent… the cumulative crush figure since April [the start of the Centre South crush season] is still running ahead of many analysts' expectations".

And while the output slowdown in the second half of November was in part down to early closures by mills which have run out of cane - with 136 plants closed for the season as of the end of last month compared with 73 by the close of November 2013 – rains also played a role, in slowing harvesting.

"The rains of the last days of November undermined harvesting operations," said Antonio de Padua Rodrigues, the Unica technical director, adding that this had prompted many mills to delay shutdown dates into early December to allow time to cut the missed cane.

Real vs dollar prices

Brazil's real also weighed on prices by falling 2.3% to touch R$2.523 to $1, its weakest since April 2005, continuing a slide underpinned by concerns over the country economy, fears which have been exacerbated by the re-election of Dilma Rousseff as president.

This week, the decline has also been fuelled by talk that Brazil will end a swap offering which has been viewed as offering some support to the real, besides by a broader move away from emerging market currencies.

A weak real reduces the value, in dollar terms, of assets in which Brazil is a big player.

Indeed, while New York raw sugar futures have fallen some 7% in the past two months, benchmark crystal sugar in Sao Paulo has appreciated by more than 4%, according to data kept by research institute Cepea.

"A weakening real against the dollar has continued to buoy domestic sugar prices, which have been posting steady increases since September," the ISO said.