A research study aimed at investigating water loss, peel appearance, and potential decay in laser-labelled grapefruit was published recently in HortTechnology. "Little information is available on the impact of this new technology on the overall quality of labelled produce, especially its effect on water loss and decay during prolonged storage", said Dr. Ed Etxeberria, who headed the research team comprised of scientists from the University of Florida and the USDA Agricultural Research Service (USDA-ARS).
"In Florida, grapefruit represents 43% of the citrus fresh market. Grapefruit require extended storage, especially when transported to international destinations. This study determined the effects of laser labelling on water loss and decay susceptibility during prolonged storage", Etxeberria explained.
During commercial production, citrus fruit is waxed before being labelled, packed, stored, and transported. Whereas common sticker-type labels do not deteriorate during storage, researchers postulated that water loss resulting from laser etching may distort the physical appearance of the fruit's surface, making it less effective and appealing. "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. These etched surfaces can promote water loss and may increase the number of entry sites for decay-promoting organisms", the researchers said.
'Red Ruby' grapefruit that had been washed and waxed with carnuba containing 15 ppm thiabendazole (following established commercial practices) was used in the study. Water loss from etched surfaces was measured, and the effect of waxing on reducing water loss from etched fruit surfaces was investigated using nine different waxes. Laser-labelled fruit stored at 10 °C and two relative humidities (95% and 65%) for 5 weeks showed no increase in decay compared with nonetched control fruit, suggesting that laser labelling does not facilitate decay. This was confirmed by experiments where Penicillium digitatum spores were coated on fruit surfaces before and after etching. In either case, no decay was observed.
The researchers concluded that, when compared with sticker-labelled fruit, laser etching provides a relatively tamper-free labelling method, while "the fruit quality remains high as the invasion of the epidermis does not incite decay, provide an avenue for food pathogens, and water loss is easily controlled. The technology will offer the grapefruit industry a safe alternative to adhesive sticker labelling without enhancing decay susceptibility."