Lactic Acid Production in Milk Containing Cleaning or Sanitizing Compounds

Area of Science:

• Dairy Microbiology
• Food Safety
• Sanitation Science

Background:

• Lactic acid bacteria (LAB) are vital for dairy fermentation and product quality.
• Effective cleaning and sanitizing agents are essential in dairy farms and factories to maintain hygiene.
• Potential interactions between sanitizers and starter cultures need thorough investigation.

Purpose of the Study:

• To evaluate the impact of common dairy cleaning and sanitizing compounds on the growth and acid production of important lactic acid bacteria.
• To identify specific compounds that inhibit or stimulate LAB at various concentrations.

Main Methods:

• Sterile reconstituted nonfat dry milk was inoculated with four LAB strains: Streptococcus lactis, Streptococcus cremoris, Streptococcus thermophilus, and Lactobacillus bulgaricus.
• Milk was incubated with 19 different cleaning/sanitizing compounds at 0.1% concentration.
• pH and titratable acidity were measured after 12 hours of incubation.
• Inhibitory compounds were further tested at lower concentrations (0.050% to 0.006%).

Main Results:

• Five compounds exhibited inhibitory effects on at least three LAB strains at 0.1%.
• Isopropanol udder wash was inhibitory to Streptococcus lactis and Streptococcus cremoris across all tested concentrations.
• Isopropanol udder wash and ammonium chloride cleaner inhibited Lactobacillus bulgaricus.
• Streptococcus thermophilus was inhibited by isopropanol udder wash and potentially stimulated by alkaline cleaner A.

Conclusions:

• Certain dairy cleaning and sanitizing agents, particularly isopropanol udder wash, can significantly inhibit the growth and acid production of crucial lactic acid bacteria.
• The choice of sanitizers must consider their potential impact on starter cultures to ensure optimal fermentation processes in the dairy industry.