During a participation cooking class last week, a student opened the refrigerator and stared at the condiment bottles in the door.

“May I help you find something?” I asked.

“Where’s the lemon juice?” she asked.

I opened the vegetable drawer and pulled out a fresh lemon.

“You have GOT to be kidding!” she answered.

Some ingredients are significantly better when used fresh instead of from a bottle. The aromatic compounds in citrus fruit are lost 30 minutes after the lemon is squeezed. Bottled juice will never have the flavor punch of fresh juice. Yes, the flavor of the dish is worth buying a fresh lemon and squeezing with our favorite citrus press.

(Our culinary bookclub just finished reading “Appetite for America” about restaurateur Fred Harvey, who threw out any standing pitchers of orange juice, since he believed that oranges must be freshly-squeezed to order.)

Fresh food costs less than packaged or prepared foods. Is the convenience of opening a bottle ever worth the high cost and loss of flavor?Jarred minced garlic or peeled garlic cloves add a bitterness not found in freshly-minced garlic cloves. Besides, most commercially-prepared garlic comes from China. Instead, buy heads of whole garlic and place the unpeeled clove in a garlic press. The skin stays in as the fresh garlic is pressed out.

Jarred roasted peppers are bland. Try home-roasting a red bell pepper — or any other kind of chile pepper. I like to place the pepper on a gas burner and cook until the pepper is completely blackened. Then I wrap in plastic until cool. The skin comes right off. The flavor is intense and smoky. Roasted red bell peppers are a great addition to so many foods: soup, salad, vegetable stir-fries, or a condiment for meats and fish.

What jarred foods are worth the cost? Foods that you cannot reproduce easily at home: olives, capers, anchovies, peppadew peppers, Dijon-style mustard, worcestershire sauce, or soy sauce. Canned tomatoes (when the label says “Ingredients: tomatoes” and nothing else) are simple and good to use, as are fruit jellies and jams. Yes, you can make jam, jelly, and canned tomatoes at home that are delicious — but I also purchase them.

And what about those nonperishable refrigerator standbys, ketchup and mayonnaise? Both are simple to make at home. My favorite ketchup recipe can be made with any fruit (tomatoes, cherries, peaches, plums, etc). Or, get inspired to make mayonnaise in Mayo Clinic.

Just don’t pop the top!