A UV photocatalytic inactivation process was used on the Space Shuttle to keep mold spore counts low.

CHICAGO – Bread bakers may turn to new allies when fighting an old nemesis. A microwave technology, live yeasts and a process used on the Space Shuttle all have shown promise in killing mold spores, said Jan van Eijk, Ph.D., research director for Lallemand Baking Solutions.

The need for new preservatives may increase for a number of reasons, Dr. van Eijk said March 3 in Chicago at the American Society of Baking’s BakingTech 2015. For one, enzymes extend shelf life by making bread softer and resilient for longer periods of time, but they do not increase mold-free shelf life. Also, reducing sodium may reduce shelf life, and “clean label” preservatives tend to be more expensive than other preservatives such as calcium propionate.

The experimental technique involving microwave technology kills mold and mold spores while the bread is in the package. Mold-free shelf life of 60 days has been achieved, but once bread is taken out of the package, mold grows at a normal pace, Dr. van Eijk said. The microwave technology may be expensive because of the equipment and space needed.

In a UV photocatalytic inactivation process, the air is treated to keep mold spore counts low. NASA used this technique in the Space Shuttle. The medical field is using UV photocatalytic inactivation in surgical rooms.

“It would be very interesting to see what it can do in bakeries,” Dr. van Eijk said.

Dr. van Eijk is one of the inventors of a patented bio control method in which live yeasts are spray-dried into bread packaging to kill mold spores. The post-baking application provides a shelf life similar to calcium propionate and may be used in conjunction with calcium propionate and other mold inhibitors.

Tests on white pan bread revealed applying calcium propionate at 0.25% led to a shelf life of seven days, which compared to five days in the control bread. The live yeasts treatment brought about a 19-day shelf life, and the combination of the live yeasts treatment and 0.25% calcium propionate extended shelf life to more than 30 days.

The live yeasts may be labeled as yeast on the ingredient list.

“It doesn’t require any label change if yeast is already used in the recipe,” Dr. van Eijk said.

He listed benefits and drawbacks to other mold-killing techniques.

Ethanol may be used as a preservative, but it requires levels as high as 1% as well as special packaging film, Dr. van Eijk said. The preservative practice of combining raisin juice concentrate and vinegar tends to not be as effective as calcium propionate, he added. Fermentates, including cultured wheat, whey or corn solids, provide shelf life similar in length to calcium propionate, but they cost more.