Organic herbs are popular among consumers of botanical dietary supplements but carry higher microbial loads, particularly yeast and mold, compared to conventional products. This makes it difficult for them to attain guidelines on microbial limits proposed by relevant authorities. It is important to find methods to reduce microbial load to within these limits using methods that conform to the "organic" ethos. This project investigates the ability of 2 heated-air drying methods (a heated room vs a flat bin dryer) to reduce microbial load, while retaining the desirable physical and chemical properties of organic herbs. OBJECTIVES: The purpose of this project is to investigate the use of different drying methods and conditions to reduce the microbial load in three herbs grown on Oregon's Wild Harvest's organic farm. The specific objectives are to a) dry the herbs using two methods available on the farm; b) vary the conditions of drying within each method; c) monitor the rate of drying of samples under the different conditions by regular sampling; d) measure microbial load at the beginning, end and intermediate stages of drying; e) for each method, compare effects on aflatoxin levels, organoleptic properties, general appearance, anatomical features and chemical profile; f)compare the cost and convenience of each process. APPROACH: The two drying methods to be used are heated room drying and flat bin drying. Temperature will be altered as the main variable. Moisture content will be measured by loss in weight and also using a moisture analyzer. Microbial load will be obtained using standard plate and broth based methods for total aerobic plate count, fecal coliforms, yeast and mold, salmonella and E. coli. A commercial ELISA based kit is available for measuring aflatoxins. The integrity of the plant material in terms of appearance and chemical content is important. Digital photography will be used to record changes in the macroscopic appearance of the herb during the drying process. A light microscope with camera attachment will be used to study changes in anatomical features, particularly oil and resin glands which may be significantly heat sensitive. Chemical profile will be studied using thin-layer chromatography and volatile oil measurements
