Microbial decontamination of food by electron beam irradiation

E-Beam Irradiation for Improving the Microbiological Quality of Smoked Duck Meat with Minimum Effects on Physicochemical Properties During Storage

This study was performed to evaluate the effect of different doses (0, 1.5, 3, and 4.5 kGy) of e-beam irradiation on the quality parameters (pH, Hunter's parameter, and heme pigment) and stability qualifiers (peroxide value [POV], thiobarbituric acid reactive substances [TBARSs], and total volatile basic nitrogen [TVBN]) of smoked duck meat during 40 d of storage under vacuum packaging at 4 °C. The initial populations of total bacteria (7.81 log CFU/g) and coliforms (5.68 log CFU/g) were reduced by approximately 2 to 5 log cycles with respect to irradiation doses. The results showed that pH, myoglobin, met-myoglobin, L^* , a^* , and b^* showed significant differences with respect to different doses and storage intervals; a^* and b^* did not vary significantly because of storage. Higher pH was found in samples treated with 4.5 kGy at 40 d, while the minimum was observed in nonirradiated samples at day 0 of storage. Higher POV (2.31 ± 0.03 meq peroxide/kg) and TBARS (5.24 ± 0.03 mg MDA/kg) values were found in 4.5 kGy-treated smoked meat at 40 d and the lowest was reported in 0 kGy-treated meat at initiation of storage (0 d). However, irradiation suppressed TVBN during storage and higher TVBN (7.09 ± 0.32 mg/100 mL) was found in duck meat treated with 0 kGy at 40 d. The electronic nose (e-nose) effectively distinguished flavor profiles during the different storage intervals. The results showed that different sensory attributes did not vary significantly with respect to the dose of irradiation. We conclude that low dose of e-beam irradiation and vacuum packaging is beneficial for safety and shelf life extension without affecting the sensory characteristics of smoked duck meat.

Pathogens Inactivated by Low-Energy-Electron Irradiation Maintain Antigenic Properties and Induce Protective Immune Responses

Inactivated vaccines are commonly produced by incubating pathogens with chemicals such as formaldehyde or β-propiolactone. This is a time-consuming process, the inactivation efficiency displays high variability and extensive downstream procedures are often required. Moreover, application of chemicals alters the antigenic components of the viruses or bacteria, resulting in reduced antibody specificity and therefore stimulation of a less effective immune response. An alternative method for inactivation of pathogens is ionizing radiation. It acts very fast and predominantly damages nucleic acids, conserving most of the antigenic structures. However, currently used irradiation technologies (mostly gamma-rays and high energy electrons) require large and complex shielding constructions to protect the environment from radioactivity or X-rays generated during the process. This excludes them from direct integration into biological production facilities. Here, low-energy electron irradiation (LEEI) is presented as an alternative inactivation method for pathogens in liquid solutions. LEEI can be used in normal laboratories, including good manufacturing practice (GMP)- or high biosafety level (BSL)-environments, as only minor shielding is necessary. We show that LEEI efficiently inactivates different viruses (influenza A (H3N8), porcine reproductive and respiratory syndrome virus (PRRSV), equine herpesvirus 1 (EHV-1)) and bacteria (Escherichia coli) and maintains their antigenicity. Moreover, LEEI-inactivated influenza A viruses elicit protective immune responses in animals, as analyzed by virus neutralization assays and viral load determination upon challenge. These results have implications for novel ways of developing and manufacturing inactivated vaccines with improved efficacy.