Raw sugar futures on ICE tumbled 3 percent on Tuesday, after technical failures triggered heavy selling, while London cocoa fell on pressure from the rallying British pound and the July contract's premium to September surged to a contract high.
Coffee futures turned lower after extending the prior session's gains to the highest levels in more than a year.
The weak session went against the day's firm trend in larger markets as the 19-commodity Thomson Reuters CoreCommodity Index rallied 1.7 percent.
Raw sugar futures initially rose but turned sharply lower, despite the firm Brazilian real.
"What I am mainly seeing is technical failures and lots of long spec positions (and) overbought levels on the chart," said Peter Mooses, senior market strategist for RJO Futures in Chicago.
Mooses noted that production concerns in Asia remain and maintained his bullish perspective.
October raw sugar settled down 0.56 cent, or 2.8 percent, at 19.72 cents per lb.
October white sugar settled down $12.01, or 2.2 percent, at $544.20 per tonne. Dealers were focused on expectations for a moderate delivery of South and Central American white sugar against expiry of the August contract on Friday.
London cocoa was pressured by the strong rebound of sterling, which supported the dollar-denominated New York market. A stronger pound makes sterling-based cocoa positions more expensive for holders of alternative currencies.
London September cocoa settled down 29 pounds, or 1.2 percent, at 2,468 pounds per tonne.
The July premium over September, however, rallied to a record for the third straight session to reach 83 pounds.
"I think it's mainly shorts getting squeezed and profit-taking by longs," Mooses said.
The market ignored the firm European grind data, which was up 5 percent and in line with expectations.
"The European grind was broadly in line with expectations. It's a function of lower grind in origin - lower availability of good quality beans, so more grind in Europe," said Eric Sivry, head of agri options brokerage at Marex Spectron.
New York September cocoa settled up $13, or 0.4 percent, at $3,114 per tonne.
Coffee futures turned lower.
September arabica coffee settled down 1.9 cent, or 1.3 percent, at $1.474 per lb, after reaching $1.514, the highest since February 2015.
September robusta coffee settled down $20, or 1.1 percent, at $1,809 per tonne.