Peptic and Tryptic Hydrolysis of Native and Heated Whey Protein to Reduce Its Antigenicity

Mean (±SD) hydrolysis of native and heated whey protein concentrate (WPC). Native and heated (10min at 100°C) WPC (2% protein solution) were incubated at 50°C for 30, 60, 90, and 120min with 0.1, 0.5, and 1% of pepsin and then trypsin on a protein-equivalent basis. Legend: native WPC 0.1% (♦), native WPC 0.5% (■), native WPC 1% (▴), heated WPC 0.1% (◊), heated WPC 0.5% (□), and heated WPC 1% (▵).

Mean (±SD) nonprotein nitrogen in enzymatic hydrolysates of native and heated whey protein concentrate (WPC). Native and heated (10min at 100°C) WPC (2% protein solution) were incubated at 50°C for 30, 60, 90, and 120min with 0.1, 0.5, and 1% of pepsin and then trypsin on a protein-equivalent basis. Legend: native WPC 0.1% (♦), native WPC 0.5% (■), native WPC 1% (▴), heated WPC 0.1% (◊), heated WPC 0.5% (□), and heated WPC 1% (▵).

Sodium dodecyl sulfate-PAGE patterns of hydrolysates of native whey protein concentrate (WPC) produced by 0.1% (A), 0.5% (B) and 1% (C) pepsin and trypsin treatments. Native WPC (2% protein solution) was incubated at 50°C for 30, 60, 90, and 120min with 0.1, 0.5, and 1% pepsin and then trypsin on a protein-equivalent basis. Lane A: standard broad-range marker (Bio-Rad, Hercules, CA): phosphorylase b (97.4 KDa), BSA (66.2 KDa), ovalbumin (45 KDa), carbonic anhydrase (31 KDa), trypsin inhibitor (21.5 KDa), and lysozyme (14.4 KDa). Lane B: native WPC. Lanes 1 to 4: native WPC hydrolysates produced by incubation with pepsin for 30, 60, 90, and 120min, respectively. Lanes 5 to 6: native WPC hydrolysates produced by incubation with trypsin for 30, 60, 90, and 120min, respectively.

Sodium dodecyl sulfate-PAGE patterns of hydrolysates of heated whey protein concentrate (WPC) produced by 0.1% (A), 0.5% (B), and 1% (C) pepsin and trypsin treatments. Heated WPC (2% protein solution) was incubated at 50°C for 30, 60, 90, and 120min with 0.1, 0.5, and 1% of pepsin and then trypsin on a protein-equivalent basis. Lane A: standard broad-range marker (Bio-Rad, Hercules, CA): phosphorylase b (97.4 KDa), BSA (66.2 KDa), oval-bumin (45 KDa), carbonic anhydrase (31 KDa), trypsin inhibitor (21.5 KDa), and lysozyme (14.4 KDa). Lane B: heated WPC. Lanes 1 to 4: heated WPC hydrolysates produced by incubation with pepsin for 30, 60, 90, and 120min, respectively. Lanes 5 to 6: heated WPC hydrolysates produced by incubation with trypsin for 30, 60, 90, and 120min, respectively.

Mean (±SD) inhibition rate of binding between native and heated whey protein concentrate (WPC) hydrolysates and rabbit antibovine whey protein antiserum. Native and heated (10min at 100°C) WPC (2% protein solution) were incubated at 50°C for 30, 60, 90, and 120min with 0.1, 0.5, and 1% of pepsin and then trypsin on a protein-equivalent basis. Legend: whey protein (•), native WPC 0.1% (♦), native WPC 0.5% (■), native WPC 1% (▴), heated WPC 0.1% (◊), heated WPC 0.5% (□), and heated WPC 1% (▵).