Cancer-fighting pink pineapples, heart-healthy purple tomatoes and less fatty vegetable oils may someday be on grocery shelves alongside more traditional products.

These genetically engineered foods could receive government approval in the coming years, following the OK given recently given to apples that don't brown and potatoes that don't bruise.

The companies and scientists that have created these foods are hoping that customers will be attracted to the health benefits and convenience and overlook any concerns about genetic engineering.

"I think once people see more of the benefits they will become more accepting of the technology," says Michael Firko, who oversees the Agriculture Department's regulation of genetically modified organisms, or GMOs.

Critics aren't so sure. They say there should be more thorough regulation of modified foods, which are grown from seeds engineered in labs, and have called for mandatory labeling of those foods. The Agriculture Department has the authority to oversee plant health of GMOs, and seeking Food and Drug Administration's safety approval is generally voluntary.

"Many of these things can be done through traditional breeding," says Doug Gurian-Sherman of the advocacy group Center for Food Safety. "There needs to be skepticism."

What could be coming next? Del Monte has engineered a pink pineapple that includes lycopene, an antioxidant compound that gives tomatoes their red color and may have a role in preventing cancer. USDA has approved importation of the pineapple, which would be grown only outside of the United States; it is pending FDA approval. A small British company is planning to apply for U.S. permission to produce and sell purple tomatoes that have high levels of anthocyanins, compounds found in blueberries that some studies show lower the risk of cardiovascular disease and cancer. FDA would have to approve any health claims used to sell the products.

Seed giants Monsanto and Dow AgroSciences are separately developing modified soybean, canola and sunflower oils with fewer saturated fats and more Omega-3 fatty acids. The Florida citrus company Southern Gardens is using a spinach gene to develop genetically engineered orange trees that could potentially resist citrus greening disease, which is devastating the Florida orange crop. Okanagan Specialty Fruits Inc., the company that created the non-browning apples, is also looking at genetically engineering peaches, cherries and apples to resist disease and improve quality.

A few genetically engineered fruits and vegetables are already available in grocery stores: Hawaiian papaya, some zucchini and squash, and a small amount of the sweet corn we eat, for example. But the bulk of the nation's genetically engineered crops are corn and soybeans that are eaten by livestock or made into popular processed food ingredients like corn starch, soybean oil or high fructose corn syrup.