title: Comparative effect of irradiation and heating on the microbiological properties of licorice (Glycyrrhiza glabra L.) root powders.
abstract: OBJECTIVE
  To determine the effect of gamma irradiation, steaming and heating on microbial load and chemical composition of licorice root powder.
  
  
  METHODS
  Powders were exposed to hot air treatment at 60°C for 24 h, steaming at 1.1 bar and about 121°C for 15 min, and irradiation at 10 kGy using a (60)Co source. Microbial load, moisture, ash, and electrical conductivity (EC) values of licorice root powders were evaluated immediately after treatment, and after 12 months of storage.
  
  
  RESULTS
  Total aerobic plate count (TAPC) of licorice roots powder (control sample), including coliform, Escherichia coli, and Klebsiella spp. were relatively high. Irradiation reduced the TAPC by 4 logs and total coliform to negative (less than 1 log(10) colony forming units (CFU) g(-1)) Klebsiella spp., E. coli, and Salmonella spp. were not detected (less than 1 log(10) CFU/g) in irradiated sample. Meanwhile, heating and steaming reduced the total count by 1 and 2 logs with slight effect on reducing the total coliforms counts. Also, irradiated samples were free of coliforms. No considerable changes in the moisture and ash were observed in irradiated powders, but the moisture increased due to steaming, and decreased due to dried heating.
  
  
  CONCLUSIONS
  Gamma irradiation at 10 kGy was more effective than heating and steaming treatments in their microbial decontamination effect on the licorice root powders.
authors: Radiation Technology Department, Atomic Energy Commission of Syria , Damascus , Syria.
authors: M
authors: M
authors: Al-Bachir
authors: M
authors: M
authors: Al-Adawi
mesh_terms: D058491:Bacterial Load / Q000528:radiation effects; D003666:Decontamination / Q000379:methods*; D005720:Gamma Rays; D006035:Glycyrrhiza / Q000737:chemistry* / Q000382:microbiology*; D006358:Hot Temperature; D018517:Plant Roots / Q000737:chemistry*; D011208:Powders; D013227:Steam
chemical_list: D011208:Powders; D013227:Steam
keywords: Licorice root powders; gamma irradiation; heat treatment; microbial load