Location: Bioproducts Research
Project Number: 2030-41000-068-006-I
Project Type: Interagency Reimbursable Agreement
Start Date: Dec 1, 2021
End Date: Sep 30, 2025
Objective:
PLU stickers on fresh fruits and vegetables contain Price Look Up codes that allow computerized price look up by a supermarket clerk while checking out groceries for customers. Paper from the PLU stickers is biodegradable, however, the adhesive on the stickers is not. France is changing standards for PLU stickers such that all stickers must be “home compostable” by 2022. If France is successful in the implementation, home compostable stickers could become the EU standard, which will significantly effect U.S. exports of fruits and vegetables to Europe thereby having a strong negative economic impact in the U.S.
The Bioproducts Research Unit at the USDA, ARS, WRRC in Albany, CA plans to develop home compostable adhesives that allow strong adherence of the stickers to produce. The adhesive will be food-grade and supply firm adherence to fruits and vegetables during transport, display, and handling at checkout. The produce PLU stickers can then go directly into a compost bin saving time and energy for the consumer who will not need to remove the sticker prior to peeling the product. This practice will also reduce the burden on landfills.
Approach:
The Bioproducts Research Unit at the USDA, ARS, WRRC, Albany, CA (BRU) will focus on developing and testing formulations that adhere compostable stickers to sweet potatoes and grapefruit, as these commodities will be most directly impacted by the French law. In addition, the loss of sweet potato and grapefruit exports to Europe will cause the most economic harm based on reports from USDA FAS and international retailers such as Walmart and Carrefour.
Many plant-based adhesives include oils, fatty acids, proteins, starches, rosins, natural latex and rubber. For use on PLU stickers, the adhesive must be food-grade which must adhere to safety and labeling requirements listed in the Fair Package and Labeling Act administered by the US FDA and must also be generally recognized as safe (GRAS).
The goal of this project is to increase the bonding strength of one or more of the aforementioned natural adhesives such that the sticker will not fall off due to exposure to a range of temperatures and humidities that are expected to be encountered during produce export, display and other handling.
To test adhesive strength, the protocol described by Doll and Erhan (2011) will be followed. Basically, the adhesive will be applied to a 1 inch portion of flat wooden stir stick and adhered to another stir stick creating an overlap. The adhesive will be allowed to dry for a predetermined period of time and the strength of the bond will be evaluated using a Instron tensile testing instrument.
To test longevity of the sticker on the produce, adhesive will be applied to a sticker and applied to whole sweet potato and grapefruit. These samples will then be subjected to simulated environmental conditions that mimic transport by ship, display and handling.
To test compostability, the adhesive will be applied to a sticker that will then be adhered to surfaces of grapefruit and sweet potato skins. The test samples will undergo compostability testing in a Respirometer which can be set to replicate home composting conditions.
