Laser Etching Safe for Labeling Fruit

Fruit can retain its quality and remain tamper free with a laser-labeling system that etches information for biosafety and traceability directly on the peel, new research shows.

The laser, which puts a permanent tattoo onto fruit rinds, could replace current stickers, which can fall off. It could also include more information because it prints on the larger surface of the fruit, proponents say. The technology is already used in New Zealand, Australia, and other countries. The U.S. Food and Drug Administration (FDA) is in the final stages of reviewing the technology.

There has been concern that the laser process could damage the fruit skin, making tiny holes that could serve as portals for bacteria and other contaminants or cause water loss. A study published in the July-September 2009 issue of HortTechnology, however, concluded that laser etching provides a relatively tamper-free labeling method when compared to stickers, and that the process does not incite decay or provide an avenue for food pathogens. In addition, water loss can be controlled by using wax to re-cover the etched area.

Research on Grapefruit

A photo of the machine that etches labels on fruit using lasers.

Researchers at the University of Florida and the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS) studied Ruby Red grapefruit with funding from Sunkist.

“In Florida, grapefruit represents 43% of the citrus fresh market. Grapefruit require extended storage, especially when transported to international destinations,” said Ed Etxeberria, PhD, who headed the University of Florida team. “This study determined the effects of laser labeling on water loss and decay susceptibility during prolonged storage.”

The study was done partly because the FDA, which considers the etching process a food additive, denied approval of the laser device when it came onto the market earlier, Dr. Etxeberria said. The agency wanted more information.

During commercial production, citrus fruit is waxed before it is labeled, packed, stored, and then transported. Sticker labels don’t deteriorate during this process. Although laser etching might seem to be an alternative, some researchers thought it might cause water loss, making the fruit look less appealing.

First Cell Layers Affected

Laser etching has been demonstrated as safe for labeling citrus fruit.

Dr. Etxeberria said each dot is etched with a carbon dioxide laser into the first few cell layers of fruit rind. “The pinhole depressions applied after washing and waxing disrupt the natural cuticular barrier and the protective commercial wax cover, seemingly creating open cavities that would allow for increased water loss and facilitating the entrance of decay organisms,” Dr. Etxeberria said. But his research found otherwise. “Decay was not enhanced by this system,” he said.

Greg Drouillard, inventor of the laser system and now director of laser research and technology at Sunkist Growers Inc., said his labeling technology is permanent, nontransferable, and tamper proof.

The scientists tested both fruit on which the etched area was re-covered with wax and fruit without that second application of wax. They investigated the effect of waxing on reducing water loss from etched fruit surfaces using nine different waxes. Laser-labeled fruit stored at 10°C and two relative humidities (95% and 65%) for five weeks showed no increase in decay compared to the control group of non-etched fruit. The results suggest that etching does not facilitate decay. That conclusion was confirmed by experiments in which Penicillium digitatum spores were coated onto fruit surfaces before and after etching, resulting in no decay in either case.

The paper concluded that “although restricted to one commodity, the study shows that laser labeling of grapefruit is a viable option to identify produce with a permanent tag.” ■