How processing may affect milk protein digestion and overall physiological outcomes: A systematic review

Area of Science:

• Food Science
• Nutritional Biochemistry
• Protein Chemistry

Background:

• Dairy proteins are vital for human nutrition, but processing can alter their quality.
• Heating milk proteins can lead to denaturation and chemical modifications, impacting digestibility and bioavailability.
• Understanding these modifications is crucial for maintaining nutritional value and physiological benefits.

Purpose of the Study:

• To systematically review the effects of heat-induced milk protein modifications on protein digestion.
• To investigate the physiological impacts of these modifications on amino acid availability and other consequences.
• To assess how processing conditions influence milk protein quality and digestion kinetics.

Main Methods:

• Systematic literature review of studies on milk protein modifications due to heating.
• Inclusion of 102 studies from an initial retrieval of 5363 records via the Scopus database.
• Analysis of in vitro and animal studies examining protein digestibility and amino acid availability.

Main Results:

• Heat-induced glycation reduces protein digestibility and lysine availability.
• Other modifications like oxidation and racemization may also impair digestion and bioavailability.
• Protein denaturation, while not affecting overall digestibility, can alter gastric hydrolysis and emptying, impacting amino acid release kinetics.

Conclusions:

• Milk protein modifications are indicators of processing severity and can significantly impact nutritional quality.
• Controlling dairy processing conditions is essential for preserving protein quality and managing gastrointestinal digestion.
• Physiological consequences primarily involve altered amino acid bioavailability and potential immunological effects.