The Effects of Ozone on Bleaching and Mold Control in Malting Process

Bleaching and mold control are of great importance to malting industry, and are normally achieved by using chlorine-containing chemicals. Ozone, a strong oxidizing agent, has been granted GRAS (generally considered as safe) status by FDA for use in food processing. It is more environmentally friendly than chlorine and yet more effective than chlorine. In this study, the effect of ozone on bleaching of barley kernels and control of mold growth during malt processing was explored. Two methods were used in the experiments, one streaking the mould on agar plates and exposure them in the atmosphere of ozone gas, the other inoculating the molds in water and bubble the ozone gas into the water. Apergillus Fischeri and Rhizopus Nigerians, the most common molds growing on grain, were the microorganism used in this study. Results show that ozone was able to increase the brightness reading by four points within two hours of the treatment, and effectively inactivate the growth of mould in gaseous and liquid conditions. The effectiveness of ozone in preventing growth of molds is affected by ozone concentration and treatment time as expected. Using 3.5% ozone, all molds were killed after 30 minutes exposure in gas, and 5 minutes bubbling in water. Further study is recommended to develop procedures for using ozone as a primary bleaching and disinfecting agent in malting industry.