Epitopes resistance to the simulated gastrointestinal digestion of β-lactoglobulin submitted to two-step enzymatic modification

• Hydrolysis and polymerization are proposed to modify βLg antigenicity.
• Alcalase was more effective in reducing βLg IgE response than bromelain.
• Polymerization affects IgE response but not epitope resistance to digestive enzymes.

The effects of β-lactoglobulin (βLg) hydrolysis with alcalase or bromelain and its association with polymerization by transglutaminase (TG) on both the protein antigenicity and resistance of epitopes to in vitro digestion were investigated. Despite the polymerization with TG altered the gastric and gastrointestinal (GI) digestion patterns of the hydrolysates with bromelain, no changes were observed with alcalase. Before and after in vitro digestion, native βLg showed the highest IgE-binding capacity, evaluated using sera from milk-allergic patients, while the enzymatic treatments—associated or not—reduced the βLg antigenicity response. Seven and four epitopes were found after gastric and GI digestion of native βLg, respectively. After gastric digestion of the hydrolysates with bromelain, two epitopes were identified, being Tyr42–Leu54 resistant to GI digestion. No epitope was found in GI digested products of hydrolysates with alcalase. Hydrolysis associated or not with polymerization reduced the number of epitopes and the IgE-binding capacity of the samples.