How do growth conditions impact heat-stable phospholipase activity in milk-contaminating bacteria? This research investigates phospholipase production by Pseudomonas isolates, psychrotrophic bacteria known to contaminate raw milk. Many such bacteria produce phospholipases that withstand pasteurization and UHT treatments, degrading milk fat globule membranes and increasing triacylglycerides, thus affecting the properties of milk. The isolates were cultured aerobically at 8 °C in various media, including nutrient broth, McKellar's minimal salts medium, Chrisope's medium, and skim milk. Each strain produced phospholipase during the 50 h incubation, but the extent of enzyme production varied significantly depending on the strain and growth medium. Strains exhibited significant differences in enzyme production across different media and throughout the incubation period. Heat stability of the enzyme activity was significantly influenced by strain, incubation time, and growth medium. Pasteurization reduced but did not eliminate the phospholipase activity in skim milk, highlighting the resilience of these enzymes. The findings underscore the need for stringent control measures to mitigate the activity of heat-stable phospholipases in dairy processing, contributing to dairy science by elucidating which growth conditions must be avoided to eliminate this contaminant.
Published in the Journal of Dairy Research, this study directly addresses a key concern in dairy science: the heat stability of phospholipases produced by Pseudomonas. By examining the impact of different growth conditions on enzyme activity, the research provides valuable insights for improving milk processing techniques and ensuring the quality of dairy products, thus aligning perfectly with the journal’s focus.
| Category | Category Repetition |
|---|---|
| Agriculture: Animal culture: Veterinary medicine | 1 |