Sterilization of food packaging by UV-C irradiation: Is Aspergillus brasiliensis ATCC 16404 the best target microorganism for industrial bio-validations?

• Published in: International journal of food microbiology 2021-11, Vol.357, p.109383-109383, Article 109383
• Main Authors: Racchi, Irene, Scaramuzza, Nicoletta, Hidalgo, Alyssa, Cigarini, Massimo, Berni, Elettra
• Format: Article
• Language: English
• Subjects: Aspergillus; Aspergillus brasiliensis; Aspergillus brasiliensis ATCC 16404; Bio-validations; Chaetomium globosum; Cytology; Decontamination; Foils; Food industry; Food irradiation; Food packaging; Food packaging industry; Heat-resistant molds; Inactivation; Inoculum; Irradiance; Irradiation; Laminates; Microorganisms; Monolayers; Multilayers; Packaging sterilization; Pigmentation; Protective structures; Solutes; Spores; Sterilization; Talaromyces; Thickness; Ultraviolet radiation; UV-C
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2021.109383

In food industries UV-C irradiation is used to achieve decontamination of some packaging devices, such as plastic caps or laminated foils, and of those smooth surfaces that can be directly irradiated. Since its effectiveness can be checked by microbial validation tests, some ascospore-forming molds (Aspergillus hiratsukae, Talaromyces bacillisporus, Aspergillus montevidensis, and Chaetomium globosum) were compared with one of the target microorganisms actually used in industrial bio-validations (Aspergillus brasiliensis ATCC 16404) to find the species most resistant to UV-C. Tests were carried out with an UV-C lamp (irradiance = 127 μW/cm2; emission peak = 253.7 nm) by inoculating HDPE caps with one or more layers of spores. Inactivation kinetics of each strain were studied and both the corresponding 1D-values and the number of Logarithmic Count Reductions (LCR) achieved were calculated. Our results showed the important role played by the type of inoculum (one or more layers) and by the differences in cell structure (thickness, presence of protective solutes, pigmentation, etc.) of the strains tested. With a single-layer inoculum, Chaetomium globosum showed the highest resistance to UV-C irradiation (1D-value = 100 s). With a multi-layer inoculum, Aspergillus brasiliensis ATCC 16404 was the most resistant fungus (1D-value = 188 s), even if it reached a number of logarithmic reductions that was higher than those of some ascospore-forming mycetes (Aspergillus montevidensis, Talaromyces bacillisporus) tested. •Resistance to UV-C light was tested on ascospore-forming molds (AFM).•AFM were compared with A. brasiliensis ATCC 16404, the target in industrial bio-validations.•Single-layer inoculum: C. globosum ATCC 6205 proved most resistant to UV-C (1D = 100 s).•Multi-layer inoculum: A. brasiliensis ATCC 16404 proved most resistant to UV-C (1D = 188 s).