Application of UV-C Light Processing on Fresh and Frozen Strawberries, Raspberries and Blueberries to Compare the Inactivation of Bacterial and Viral Pathogens and Their Surrogates and Evaluate the Sensory Aspects of This Technology

Introduction: Several foodborne outbreaks associated with strawberries have raised safety concerns about various fresh and frozen berry products in recent years. UV-C is applied for the disinfection of drinking water and is considered to be a promising technology for a wider range of beverages and food products. The berry industry needs novel approaches to address the current microbiological issues, especially viruses.

Purpose: The objective of this study was to evaluate the sensory effects of UV-C technology and to compare the inactivation of bacterial and viral pathogens and their surrogates on fresh and frozen strawberries, raspberries and blueberries using UV-C light to critically assess the potential of this technology for the berry supply chain.

Methods: Fresh and frozen strawberries, raspberries and blueberries were spot-inoculated with Listeria, Salmonella, STEC, Hepatitis A virus (HAV) and their surrogates (L. innocua, E. faecium, E. coli and MS2 bacteriophage) and treated with UV-C using a 95W high output UV-C emitter. Samples were exposed to UV-C for up to 2 minutes. After treatment, microorganisms were extracted and recovered from the samples and quantified using selective media for the bacteria and infectivity assays for the viruses.

Results: Results show a similar reduction on fresh and frozen berries with a significant difference between berry types for the different microorganisms tested. UV-C treatment did not show an obvious impact on the sensory aspects of berries.

Significance: The present study demonstrates that UV-C treatment has the potential to be applied at different steps along the berry supply chain to improve the microbial safety of fresh and frozen berries.