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SOLUBILITY AND EMULSIFYING PROPERTIES OF BETACASEIN MODIFIED ENZYMATICALLY BY TRYPSIN
Author(s) -
CHOBERT JEANMARC,
BERTRANDHARB CATHERINE,
DALGALARRONDO MICHELE,
NICOLAS MARIEGEORGETTE
Publication year - 1989
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1989.tb00403.x
Subject(s) - hydrolysis , casein , chromatography , chemistry , hydrolysate , trypsin , solubility , sodium dodecyl sulfate , size exclusion chromatography , molecular mass , biochemistry , organic chemistry , enzyme
Beta A1‐casein was treated with TPCK‐trypsin to give 3.2, 5.0, 5.8 and 7.4% hydrolysis of the peptide bonds. By sodium dodecyl sulfate‐polyacrylamide gel electrophoresis the resulting peptides had apparent molecular weights in the range 8,000–4,000. Size‐exclusion chromatography of hydrolyzed samples showed four major peaks near 15,000, 5,500, 3,500 and 2,500 molecular weights, representing 17, 15, 7 and 14% of the material, respectively, after 3.2% hydrolysis and 9, 6, 14 and 52% of the material, respectively, after 7.4% hydrolysis. Between the extremes 3.2% and 7.4% hydrolysis, a peak near 8,500 molecular weight was present until 5.8% hydrolysis then disappeared after 7.4% hydrolysis to be replaced by a peak near 12,000 molecular weight. Peptides recovered from reversed‐phase high performance liquid chromatography were analyzed by determination of their amino acid composition and identified in the sequence of β‐casein. After trypsin treatment, the solubility of β‐casein hydrolysates was largely increased at pH 4.0–7.5. The emulsifying activity of the hydrolysates was higher than that of β‐casein in the range of pH 1.5–3.5 and 6.5–10.0, but all the emulsions obtained with trypsin‐treated β‐casein were less stable than those obtained with original β‐casein.