The role of gamma irradiation and storage at 28 ± 2 °C on the inactivation of Listeria monocytogenes, Escherichia coli and Salmonella enterica serotype Typhimurium in sun-dried Legon-18 pepper (Capsicum annuum) powder

Abstract

Abstract Low moisture foods like spices are known to be contaminated with pathogens, sun-dried chili pepper powder not left out. A study was conducted to determine the effect of gamma irradiation on the decontamination of sun-dried Legon-18 pepper powder and its impact on some quality parameters. Samples were obtained from a local farmer. Sterility tests was performed. Samples were inoculated with known cfu/g of L. monocytogenes, E. coli and S. Typhimurium. The inoculated samples were irradiated at 1, 2, 4 and 5 kGy and unirradiated samples were used as control (0 kGy). The samples were stored for 60 days at 28 ± 2 °C and pathogens enumerated in the appropriate medium. For quality parameters, samples were irradiated at 5 kGy, unirradiated samples served as control (0 kGy) and stored at 28 ± 2 °C. HPLC was used for the quantification of carotenoids and capsaicinoids in the samples that were stored for 8 weeks at 28 ± 2 °C. A dose-dependent effect on the inactivation of the pathogens used in the study as well as the effect of storage days was observed (p < 0.05). All the pathogens used in the study were inactivated at 5 kGy on day 0. Gamma irradiation at 5 kGy caused an increase of 21.81% in capsaicin, 16.79% in dihydrocapsaicin and 20.32% in total capsaicinoids in the irradiated samples. The effect of gamma irradiation on the carotenoids led to losses of 8.84% in beta carotene, 26.07% in beta cryptoxanthin and 8.16% in capsanthin. Storage weeks caused losses in all carotenoids and capsaicinoids analyzed during the study.

Keywords

• Capsaicinoids
• Carotenoids
• Gamma irradiation
• Storage
• Scoville heat units
• Inactivation