A major innovation in food processing that eliminates undesired mushiness in canned vegetables and fruits was announced here Tuesday by a scientist from Cornell University.
The new process produces canned carrots, beans and other vegetables that are almost as firm and crunchy as fresh produce. It also works to a lesser degree on fruits.Dr. Malcolm C. Bourne, developer of the process, described it as one of the most exciting advances in canning technology since Nicholas Appert delighted Napoleon with the invention of canning in 1810.
Although further work will be needed to perfect the new technology, Bourne predicted it will have a far-reaching impact on consumers and food processors within two to five years.
"We think the time will come when half the items in the salad bar or the stir-fry pan in your favorite restaurant will come from tin cans instead of the refrigerator," Bourne said.
Bourne is an authority on food texture, a professor of food science and technology at Cornell's agricultural research center.
Likewise, the process could help to reverse a long decline for the canned fruit and vegetable industry, whose sales have been falling about 1 percent a year for 15 years.
Bourne said that consumers demanding vegetables with a firm, crisp texture have forsaken canned produce for frozen or fresh vegetables.
He reported development of the new process at the 198th national meeting of the American Chemical Society, being held here this week.
It originated through basic understanding of the chemical changes that occur in fruits and vegetables during cooking. Cooking softens the texture of fruits and vegetables by unraveling the molecular structure of pectins. The longer the heating time, the softer the fruit or vegetable becomes. The problem is especially serious with canned vegetables, which must be heated for long periods to kill bacteria that cause spoilage.
Conventional canning of vegetables involves two basic steps. One is a short period of blanching, or heating vegetables in water to drive out gases so that more vegetables can be packed in jars or cans. The second is a longer period of heating to kill microrganisms that otherwise would cause spoilage.
The new process involves reducing blanching temperatures and adding a brief holdng period to allow a naturally occurring enzyme to "fix" the crispness in fruits and vegetables. The enzyme, pectin methyesterase, reverses some of the softening effects of cooking. The process also involves the addition of calcium, which the enzyme uses to repair cooking-related damage in pectin, and citric acid to produce the required acidic conditions.
The process actually gives vegetables long-lasting thermal stability. Vegetables canned with the process can be recooked for hours and still remain firm.
Bourne said three commercial canning firms already are evaluating the process, which has been patented by Cornell.