Microbial decontamination of medicinally important herbals using gamma radiation and their biochemical characterisation

A comprehensive study was carried out to assess the microbiological and biochemical characteristics of four herbals, namely, rose (Rosa centifolia), guggul (Commiphora mukul), chirata (Swertia chirayita), gulvel (Tinospora cordifolia) and four herbal formulations rasayan, shatpatryadi, scrub and kashayam. Total aerobic plate count (TAPC) was in the range of 3–7 log cfu/g, whereas, presumptive coliform count in many of these samples was in the range 2–6 log cfu/g. The IMViC (indole, methyl red, Voges-Proskauer, citrate) analysis and molecular characterisation (16S rDNA sequencing) ascertained the presence of Escherichia coli in some of the samples. A gamma radiation dose of up to 10 kGy was found to be sufficient for complete microbial decontamination without affecting the bioactive properties of herbal formulations, including antioxidant potential, which was high in rasayan, shatpatryadi, scrub, rose, and guggul. The antioxidant property of these herbals could be attributed to components such as phenolics, flavonoids and colour pigments.