Gita Zulfie Ramadhani, Lilik Eka Radiati
Milk is a perishable, nutrient-rich commodity prone to microbial contamination, including pathogens such as Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes. These findings are crucial for optimizing ozone-based, non-thermal inactivation strategies, as the protein and fat components of skim and full cream milk powders can act as protective barriers that shield bacteria from ozone-induced oxidative damage, leading to their inactivation. A Completely Randomized Design (CRD) was conducted at Universitas Brawijaya using fresh milk inoculated with the target bacteria. Samples were treated with ozone gas produced by a Hanaco ozone generator at 0.28 mg/L for 0, 10, 20, and 30 minutes. Skim and full cream milk powders were added at concentrations of 2, 4, 6, and 8 g per 100 mL. Bacterial populations were analyzed using selective agar media after inoculation with standardized suspensions of Escherichia coli, Staphylococcus aureus and Listeria monocytogenes. Ozonation for 30 minutes reduced total bacteria counts by 0.22 log CFU/mL. In skim milk, Listeria monocytogenes survivability increased slightly, reducing only 0.06 log CFU/mL and rising from 8.61 to 9.23 log CFU/mL. Staphylococcus aureus decreased by 1.19 log CFU/mL, ranging from 8.93-9.34 in skim and 9.96-9.98 in full-cream milk. Escherichia coli declined from 8.93 to 8.00 in skim but rose from 8.20 to 8.82 in full-cream milk, indicating lipid interference with ozone activity. In conclusion, while ozone effectively reduces microbial contamination, its sterilization efficacy is significantly influenced by the milk’s nutrient matrix. These findings are crucial for optimizing ozone-based, non-thermal pasteurization strategies in dairy processing. © 2026, Research Institute of Food Science and Technology. All rights reserved.
Department of Livestock Technology, Animal Science, Universitas Brawijaya, East Java, Malang, Indonesia
