Impact of Irradiation on the Protein Content and Microbial Levels of Sesame Seed Flour for use in Oral Immunotherapy
Monday, March 5, 2018
South Hall A2 (Convention Center)
Anusha Penumarti, PhD, Nicole Szczepanski, Janelle Kesselring, Elizabeth Gabel, Jelena Petrovic Berglund, PhD, RAC, Edwin H. Kim, MD, A. Wesley Burks, MD FAAAAI, Mike D. Kulis, PhD

Sesame seed flour used in oral immunotherapy studies has to meet specific criteria for allergen content and bioburden according to FDA guidelines for orally administered drugs. Thermal processing of sesame flour failed to decrease the microbial content and increase its shelf life. We studied the effect of gamma irradiation (a type of cold sterilization) on the protein content and bioburden of sesame flour allergens (Ses i 3 and Ses i 2).


SDS-PAGE analysis coupled with densitometric scanning was conducted on sesame seed flour exposed to gamma irradiation (Minimum/Maximum Dose of 5.0kGy – 30.0kGy) to determine the effect of irradiation on protein content. Irradiated and non-irradiated sesame flour was tested for the presence of Escherichia coli, Salmonella, aerobic bacteria, mold and yeast levels.


Irradiating sesame flour resulted in <10% variance in the content of Ses i 3 and Ses i 2 proteins as revealed by SDS-PAGE and densitometry analysis. Bioburden testing revealed a significant decrease in aerobic plate count (>2500cfu/g in non-irradiated to <10cfu/g in irradiated flour) and Escherichia coli levels (Positive/10g in non-irradiated to Negative/10g in irradiated). Importantly, the levels of all microbes after irradiation met criteria established by FDA for an orally delivered drug product.


Irradiation of sesame seed flour leads to a significant decrease of bioburden levels without significantly altering the protein content. Future studies will determine the effect of irradiation on the allergenicity of sesame seed proteins using Western blotting, ELISA and basophil activation testing.