Here is an interesting article on Ozone Treatments for Liquid Based Foods from KnowledgeE – only a portion is reproduced below, please follow the link for the full article.



“Ozone treatment on liquid based foods

Ozone is also applied to ensure the safety of food products including some liquid based foods such as milk and juice where above 80% consist of water. Ozonation in some liquid based foods are influenced by several factors, such as temperature, retention time, ozone concentrations, pH. At high temperature, the resistance and the existence of ozone in the water is reduced. The retention time of ozone in water at a temperature of 25 ∘C was 15 minutes, while at a temperature of 35 ∘C is 8 minutes. Retention time of ozone in water is decrease with the increase of water temperature. Meanwhile, water with an acidic pH can inhibit the decomposition of ozone, due to the low pH which indicates high alkalinity, thus can cause ozone retention time increases. Concentration of ozone and its retention time have important role in determining the efficiency of ozonation. Time of ozonation is the amount of time required by ozone to inactivate microorganisms in the medium such as water or liquid based foods. The concentration and time of application is used to calculate the amount of disinfectant needed and to determine the effectiveness of a particular disinfectant in killing microorganisms in liquid food.

The concentration of ozone is used to inactivate microorganisms in the medium of water or liquid based foods is about 0.5 to 4.0mg/L. For E.coli and Streptococcus which are found in milk, at pH 7.0 and temperature 25∘-30∘C, the ozone concentration of 0.01 mg/L was high enough to inactivate such microorganism. Ozone will react with all protoplasm cells by acting as an oxidant. Ozone will directly attacking the surface layers of bacteria, oxidized the sulfhydryl of the enzyme, or oxidized the lipoprotein and the lipopolysaccharide which are the inner layer of the gram-negative bacteria. This process lead to a breakdown of the cell permeability defense so that the cell becomes paralysis. Only 1% of E. coli and Streptococcus was left after contact with 0.8 mg/L of ozone for 60 seconds. Furthermore, Cavalcante et al found that the raw milk studied showed an adequate microbiological quality and the ozonation for 15 minutes was able to causes 0.5 to 1 decimal reductions in the milk native flora. Complementary, no changes were observed in the physicochemical parameters of the milk. Thus, the results highlight the ozonation could used as an alternative method to reduce the microbial load in raw milk, improving its quality and increasing the milk shelf-life before thermal processing. Residues of ozone are toxic to all kind of microorganism, but the ozone easily biodegradable. Ozone only last for a few minutes in water base material so that the residual of ozone is already disappear and harmless to organisms that use them.”