Loss of miRNAs during processing and storage of cow's (Bos taurus) milk

Area of Science:

• Biochemistry
• Molecular Biology
• Food Science

Background:

• MicroRNAs (miRNAs) are crucial regulators of gene expression.
• Previous research indicated that miRNAs in pasteurized bovine milk retain biological activity in humans.
• The stability and concentration of these milk-derived miRNAs under various conditions remain incompletely understood.

Purpose of the Study:

• To investigate the impact of milk processing, storage conditions, somatic cell count, and consumer handling on miRNA degradation.
• To quantify miRNA levels in various dairy products.
• To determine the influence of milk fat content on miRNA stability.

Main Methods:

• Quantitative analysis of specific miRNAs (miR-200c, miR-29b) in milk subjected to different treatments.
• Assessment of miRNA degradation following pasteurization, homogenization, microwave heating, and cold storage.
• Comparison of miRNA concentrations in raw milk, processed milk, and derived dairy products.

Main Results:

• Pasteurization and homogenization led to significant losses of miR-200c (63%) and miR-29b (67% in skim milk).
• Microwave heating caused a 40% reduction in miR-29b, while miR-200c remained stable.
• Cold storage and somatic cell content had minimal effects (<2% loss) on miRNA levels. Dairy products exhibited considerably lower miRNA concentrations than store-bought milk.

Conclusions:

• Dairy processing methods, including pasteurization and homogenization, significantly diminish miRNA content in bovine milk.
• Consumer-level handling, such as microwave heating, further contributes to miRNA loss.
• The concentration of bioactive miRNAs in dairy products is substantially lower compared to fluid milk, suggesting reduced biological activity.