The largest union at Hostess Brands Inc. won one round in its battle with the bankrupt maker of Twinkies and Wonder Bread.

Late on Monday, a federal bankruptcy judge denied Hostess’ motion to scrap employment contracts with the Teamsters. That marked a victory for workers at Hostess, which employs 370 workers in Biddeford.

“It’s a rare day when a bankruptcy judge denies a company’s request to reject its union contracts,” said Teamster General Secretary-Treasurer Ken Hall. “We told our Hostess members all along that we would vigorously oppose the imposition of unjust working conditions since Hostess first filed bankruptcy and we have done just that.”

Last week, a smaller union at Hostess wasn’t so lucky. The judge ruled that Hostess could abandon some contract agreements and modify some retiree benefits with the Bakery, Confectionery, Tobacco Workers and Grain Millers International Union. The status of some contested agreements are scheduled to be decided at a hearing on Wednesday.

Hostess, which is embroiled in its second bankruptcy in less than a decade, employs 18,500 workers nationally.

Its unions have threatened to strike if its contracts are voided and Hostess imposes new work rules. Hostess has said a strike would force it to liquidate.