Mustardseed futures prices turned weak by losing Rs 7.55 to Rs 567.40 per 20 kg today on profit booking at higher levels.
Marketmen said traders preferred to book profits at existing higher levels.
At National Commodity and Derivatives Exchange platform, mustardseed price for December delivery moved up by Rs 7.55, or 1.31 per cent, to Rs 567.40 per 20 kg, showing an open interest of 68,730 lots.
Most active November-month contract, too, followed suit and went down by Rs 7.30, or 1.29 per cent, to Rs 560.30 per quintal, with an open interest of 1,39,270 lots.