CO2 Laser-labeling on Fresh Produce: Evaluating Postharvest Quality, Microbial Safety, and Economic Analysis.

Fresh produce is traditionally labeled with plastic price lookup (PLU) stickers that are attached to the produce surface using edible glue. However, both the stickers and glue are environmental contaminants, and the stickers can still easily detach from the produce surface during handling and disrupt traceability. An alternative method of labeling, the CO2 laser-labeling technology (LLT), has been gaining attention in recent years. However, engraving Quick Response (QR) code using LLT is unique, and the performance of this technology varies from produce item to produce item, and information on its effects on postharvest quality, microbial safety, and economic feasibility has not been reported. The objectives of this study were to investigate the effect of laser-labeling technology on (1) postharvest quality, (2) microbial safety, and (3) economic analysis of this technology. Three horticultural crops, 'Red Delicious' apple (Malus pumila), green bell pepper (Capsicum annuum), and cucumber (Cucumis sativus) were procured from a local grocery store. Each produce was engraved with a Quick Response (QR) code or 6-digit alphanumerical (text) code using the commercially available Trotec Speedy 300 CO2 laser engraver, followed by the application of edible wax. Fresh weight loss for laser-printed produce was higher compared to controls, but no difference in visual quality ratings was observed. The laser-labeled produce was assessed for microbial contamination by artificially inoculating rifampicin-resistant Escherichia coli (E. coli) log10 6 CFU/mL to the labeled fruit. The results showed that the population of rifampicin-resistant E. coli was statistically higher in all three products labeled with text code compared to the nontreated controls. The QR-coded treatments were similar to the controls. The wax application did not affect the microbial attachment on the laser-labeled produce. The CO2 laser labeling technology has the potential for industrial application.

Developing a Decision-making Tool for Agricultural Surface Water Decontamination Using Ultraviolet-C Light.

Ultraviolet-C (UV-C) light-assisted water treatment systems are an increasingly investigated alternative to chemical sanitizers for agricultural surface water decontamination. However, the relatively high concentration of particulate matter in surface water is a major challenge to expanding its application in the production of fresh produce. The objective of this project was to test the efficacy of two commercial UV-C devices to reduce the microbial risk of agricultural water in order to develop a web application to assist growers in decision-making related to the on-farm implementation of UV-C technologies for agricultural water treatment. An on-farm study using three agricultural water sources was performed to determine the microbial reduction efficacy of a low power, low flow (LP/LF; 1-9 gallons per minute (GPM), 1.34-gallon capacity) and a high powered, high flow (HP/HF; 1-110 GPM, 4.75-gallon capacity) device at flow rates of 6, 7, and 9 GPM. A threshold of 30% UVT for the HP/HF device was observed, wherein lower water transmissibility significantly impacted microbial inactivation. Although less effective at lower %UVT, the LP/LF device costs less to install, maintain, and operate. The observations were used to design an online tool for growers to calculate the predicted reduction of generic Escherichia coli using either device based on the %UVT of their water source. However, because this study utilized an exploratory and proof-of-concept approach, the experimental flow rates were limited to reflect the capacities of the smaller unit (9 GPM) for direct comparison to the larger unit. Thus, the preliminary model and tool are largely limited to the experimental conditions. Yet, these results of this study demonstrate the utility of UV-C light in reducing the microbial risk of agricultural water, and future studies using different UV-C devices and higher flow rates will expand the use of the decision-making tool.