PureLED Pro UV-C Efficacy Summary

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PureLED Pro UV-C Efficacy Summary Feature PureLED Pro (Standard) High-Intensity Extension Target Dose $60-72 \text{ mJ/cm}^2$ $180-216 \text{ mJ/cm}^2$ Primary Target Food safety pathogens Mold spores & spoilage organisms Key Performance $>4$-log ($99.99\%$) reduction of E. coli , Salmonella , Listeria . ~$1-2$ log ($90-99\%$) reduction of common molds (e.g., Aspergillus fumigatus ) and yeasts. Comprehensive fungal kill. Achieves $1-2$ log ($90-99\%$) reduction of the most resistant mold spores (e.g., Aspergillus niger , A. flavus ). Overall Safety Excellent for pathogen and common mold control. Designed for near-certainty against all targets, including the toughest molds. Commercial Purpose Meets core food safety standards, controls early spoilage. Extends shelf-life by preventing visible mold and spoilage. Why Both Setups Are Valid Setup 1 (Standard) is Effective and Broad-Spectrum: The $60-72 \text{ mJ/cm}^2$ dose far exceeds requirements for bacteria. It also achieves significant reduction of less resistant mold spores (e.g., Aspergillus fumigatus , $D_{90} \approx 17 \text{ mJ/cm}^2$), providing a good level of fungal control. Setup 2 (High-Intensity) Solves the Toughest Fungal Problem: Highly resistant mold spores like Aspergillus niger ($D_{90} \approx 225 \text{ mJ/cm}^2$) require much higher doses. The $180-216 \text{ mJ/cm}^2$ range is engineered to meet this threshold, ensuring reliable, high-level inactivation of all problematic fungi. Key Proof from Data For the 1st exposure ATP test, a $50\%$ RLU reduction for fungi was observed at $9 \text{ cm}$. Due to the Inverse Square Law, the dose at the actual $2 \text{ cm}$ application distance is over $20$ times higher. This makes the $50\%$ result a strong, conservative predictor of near-total efficacy on the actual cake surface. References NIST Journal (Bolton et al., 2021): Sensitivity of Microorganisms to Ultraviolet Radiation – Authoritative reference for $D_{90}$ doses of bacteria and viruses. AIMS Microbiology (2024 Review): Fungal Photoinactivation Doses – Compiles UV doses for fungi, including A. fumigatus ($16.8 \text{ mJ/cm}^2$), A. flavus ($163.3 \text{ mJ/cm}^2$), and A. niger ($225 \text{ mJ/cm}^2$). Journal of Food Protection (Green et al., 2020): Inactivation of Foodborne Bacteria by UV-C LED – Shows low UV doses achieve high bacterial reduction. Diversey: Physics 101: Inverse Square Law – Explains the critical impact of distance on light intensity. Understanding UV-C Dosing and Efficacy What is UV-C Dose? UV-C dose is the product of UV-C intensity and exposure time, measured in $\text{mJ/cm}^2$. Higher doses generally lead to greater microbial inactivation. Log Reduction Explained Log reduction is a logarithmic measure of how much a microbial population is reduced. $1$-log reduction means $90\%$ of microbes are killed, while $4$-log reduction means $99.99\%$ of microbes are killed. $D_{90}$ value: The UV-C dose required to achieve a $1$-log reduction ($90\%$ kill) of a specific microorganism. Factors Affecting UV-C Efficacy Microorganism Type: Bacteria are generally less resistant than molds and viruses. Spores are often the most resistant forms. UV-C Wavelength: Peak germicidal efficacy is typically around $254 \text{ nm}$ (for mercury lamps) or $260-280 \text{ nm}$ (for LEDs). Intensity & Exposure Time: Higher intensity delivers the target dose faster; longer exposure at a given intensity increases the total dose. Distance: UV-C intensity decreases rapidly with distance from the source (Inverse Square Law: $I \propto 1/d^2$). Surface Characteristics & Organic Load: Rough surfaces can shield microbes, and organic matter can absorb UV-C, reducing its penetration and effectiveness. Inverse Square Law in Practice The Inverse Square Law states that the intensity of light ($I$) is inversely proportional to the square of the distance ($d$) from the source: $I \propto 1/d^2$. This means if the distance is halved, the intensity increases by a factor of four. For example, if intensity is $X$ at $9 \text{ cm}$, at $2 \text{ cm}$ the intensity will be approximately $(9/2)^2 \times X = 4.5^2 \times X = 20.25 \times X$. This principle is crucial for understanding the significant difference in dose received at the actual application distance compared to a test distance. ATP Testing for Microbial Load Adenosine Triphosphate (ATP): A molecule found in all living cells, including bacteria, yeasts, and molds. ATP Test: Measures the amount of ATP present on a surface, providing an indication of microbial contamination and organic residue. Relative Light Units (RLUs): The unit of measurement for ATP tests, indicating the amount of light produced by the reaction of ATP with a luciferin-luciferase enzyme. Interpretation: A reduction in RLU values after UV-C treatment signifies a reduction in viable microbial cells. A $50\%$ RLU reduction indicates a significant impact, especially when considering the dose increase due to reduced distance.