In the story "A Jury of Her Peers," what is the only unbroken jar of fruit in the cupboard filled with?

In Elizabeth Glaspell's short story, the county attorney first notices that the jars of fruit have broken with the cold. He stands on a chair to inspect the upper cupboard and finds the burst jars. He feels inside and "drew his hand away sticky," remarking on the "nice mess." He then goes to wash his hands in the sink, criticizing the unwashed pans underneath it and the dirty roller towel beside it. The women, especially Mrs. Hale, are offended at how dismissive the men are about a farm wife's occupation. Mrs. Peters, the sheriff's wife, knows Mrs. Wright expressed concern about her fruit should the fire go out in the house, and the attorney mocks the concern as being a "trifle." 
After the men go upstairs, Mrs. Peters stands on the chair herself to see if any of the jars of fruit are undamaged. She finds a single jar of cherry preserves that has not exploded. 
The preserves serve as a bonding point among the three women: Mrs. Hale, Mrs. Peters, and Mrs. Wright. They also set them at odds with the men, who diminish women's roles. By the end of the story, Mrs. Peters determines to tell Mrs. Wright all the preserves were fine. The single remaining jar of cherry preserves becomes a symbol that Mrs. Wright's life will be preserved, despite the "nice mess" she finds herself in, because the other two women determine to act as a jury of her peers—a right she would not receive in the judicial system of the day.