More than 300 members of the United Food and Commercial Workers union picketed the Ralphs Grocery Co. headquarters in Compton. Employees at Ralphs, the largest supermarket chain in Southern California, claim that they must accept demotion with less pay or be laid off. Union spokesman Dan Swinton said about 1,000 workers have been laid off during the last 16 months and have been replaced by younger, less experienced employees at lower pay. He added that about 800 employees have been demoted or had their work hours reduced. Gene A. Brown, Ralphs senior vice president of human resources, said that 173 food clerks, including 21 full-time employees, have been laid off in a one-year period in the 126 Ralphs stores in Southern California.