Effect of Processing Intensity on Immunologically Active Bovine Milk Serum Proteins

Abstract

Consumption of raw cow’s milk instead of industrially processed milk has been reported to protect children from developing asthma, allergies, and respiratory infections. Several heat-sensitive milk serum proteins have been implied in this effect though unbiased assessment of milk proteins in general is missing. The aim of this study was to compare the native milk serum proteome between raw cow’s milk and various industrially applied processing methods, i.e., homogenization, fat separation, pasteurization, ultra-heat treatment (UHT), treatment for extended shelf-life (ESL), and conventional boiling. Each processing method was applied to the same three pools of raw milk. Levels of detectable proteins were quantified by liquid chromatography/tandem mass spectrometry following filter aided sample preparation. In total, 364 milk serum proteins were identified. The 140 proteins detectable in 66% of all samples were entered in a hierarchical cluster analysis. The resulting proteomics pattern separated mainly as high (boiling, UHT, ESL) versus no/low heat treatment (raw, skimmed, pasteurized). Comparing these two groups revealed 23 individual proteins significantly reduced by heating, e.g., lactoferrin (log2-fold change = −0.37, p = 0.004), lactoperoxidase (log2-fold change = −0.33, p = 0.001), and lactadherin (log2-fold change = −0.22, p = 0.020). The abundance of these heat sensitive proteins found in higher quantity in native cow’s milk compared to heat treated milk, renders them potential candidates for protection from asthma, allergies, and respiratory infections.

Milk processing increases the allergenicity of cow’s milk—Preclinical evidence supported by a human proof‐of‐concept provocation pilot

“…Previous studies have speculated the whey protein fraction of raw milk may be a source of the allergy‐protective components . To assess whether the reduced sensitizing capacity of raw milk is still present when only looking at the whey protein fraction of the milk, a similar experiment was conducted with native and heated whey proteins (Figure B).…”

“…However, milk processing also induces unwanted changes in the milk composition. Proteins with potential beneficial health properties (partly) lose functionality, and the context of allergen presentation to the immune system may be altered . Current literature mostly demonstrates the adverse effect of milk processing on allergic diseases like asthma and atopy .…”

“…Milk processing, especially heating, abolishes the allergy‐protective effects observed after consumption of raw cow's milk. This loss of protection is often attributed to the denaturation, and subsequent loss of functionality of immunomodulatory proteins present in the whey fraction of the milk . However, whether milk processing also affects the allergenicity of the milk is barely researched.…”

“…Heat treatment, in particular, appears to impact the protective effect, suggesting the importance of heat‐sensitive milk components, such as whey proteins . From a variety of these whey proteins, it is believed that they might contribute to the protective effects of raw cow's milk . Whether these components by themselves have the capacity to reduce the asthma and allergy risk remains to be elucidated.…”

“…7,12,13 From a variety of these whey proteins, it is believed that they might contribute to the protective effects of raw cow's milk. 14,15 Whether these components by themselves have the capacity to reduce the asthma and allergy risk remains to be elucidated.…”