Precipitation of hydrophobic peptides from tryptic casein hydrolysate by salt and pH
1994; Elsevier BV; Volume: 16; Issue: 7 Linguagem: Inglês
10.1016/0141-0229(94)90124-4
ISSN1879-0909
AutoresJoëlle Léonil, Daniel Mollé, Saı̈d Bouhallab, G. Henry,
Tópico(s)Proteins in Food Systems
ResumoThe precipitation of peptides derived from tryptic hydrolysis of caseins was studied as a function of the pH (3.5 to 7.5), ionic strength (from 0 to 1 m), and the chemical nature of the salt [NaCl (NH4)2 SO4] at 25°C. Precipitation occurred only in the acidic pH range. The precipitated fraction, analyzed by RP-HPLC, was constituted by a specific hydrophobic peptide group. The nine major peptides were identified as κ-CN (35–63), αs1-CN (91–100), αs1-CN (125–151), αs1-CN (152–193), β-CN (49–97), β-CN (108–169), β-CN (114–169), β-CN (184–202), and β-CN (184–209). The optimum precipitation was found to be at pH 3.5 and 0.25 m NaCl except for β-CN (184–202) and αs1-CN (125–151), which required a higher ionic strength. The results showed that pH had a greater effect on the precipitation of peptides than salt. However, neither pI nor hydrophobicity alone could have explained the salting-out behavior; probably a combination of the two properties is responsible.
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