DENVER — With the authority of a celebrity chef, Adam Fisher gestured toward the bushels of fresh basil, oregano and parsley sitting on the counter in front of him, as the crowd leaned forward.

“We almost want to treat fresh herbs like we treat fresh flowers,” he commanded, speaking into a microphone clipped to his apron. “You want to snip off the ends, and ideally you want to store them in some water.”

Mr. Fisher may not be some fast-talking TV personality, but he is a chef, a food supervisor for the Denver Public Schools, and he was giving a demonstration on how to whip up cafeteria food — in this case, cucumber and pasta salads — from scratch.

With new federal standards for school meals going into effect this month, and a renewed focus on the issue brought by the first lady, Michelle Obama, thousands of school chefs, food service workers and nutrition experts from around the country gathered in Denver this week at an annual conference put on by the School Nutrition Association, a nonprofit organization of school food professionals.