Effect of High-pressure Treatment on the Tryptic Hydrolysis of Bovine β-Lactoglobulin AB

Effects of high pressure (HP) on average casein micelle size and denaturation of α-lactalbumin (α-la) and β-lactoglobulin (β-lg) in raw skim bovine milk were studied over a range of conditions. Micelle size was not influenced by treatment at pressures <200 MPa, but treatment at 250 MPa increased micelle size by ∼25%, while treatment at [ges ]300 MPa irreversibly reduced it to ∼50% of that in untreated milk. The increase in micelle size after treatment at 250 MPa was greater with increasing treatment time and temperature and milk pH. Treatment times [ges ]2 min at 400 MPa resulted in similar levels of micelle disruption, but increasing milk pH to 7·0 partially stabilised micelles against HP-induced disruption. Denaturation of α-la did not occur [les ]400 MPa, whereas β-lg was denatured at pressures >100 MPa. Denaturation of α-la and β-lg increased with increasing pressure, treatment time and temperature and milk pH. The majority of denatured β-lg was apparently associated with casein micelles. These effects of HP on casein micelles and whey proteins in milk may have significant implications for properties of products made from HP-treated milk.

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Oligomerization of β-lactoglobulin by microbial transglutaminase during high pressure treatment

European Food Research and Technology ◽

10.1007/s002170100368 ◽

2001 ◽

Vol 213 (3) ◽

pp. 246-247 ◽

Cited By ~ 18

Author(s):

Sabine Lauber ◽

Ivonne Noack ◽

Henning Klostermeyer ◽

Thomas Henle

Keyword(s):

High Pressure ◽

Microbial Transglutaminase ◽

Pressure Treatment ◽

High Pressure Treatment ◽

Β Lactoglobulin

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Kinetics of Refolding of β-Lactoglobulin after High-pressure Treatment Measured by Reactivity Towards Ellman's Reagent

High Pressure Food Science, Bioscience and Chemistry ◽

10.1533/9781845698379.5.376 ◽

1998 ◽

pp. 376-380

Author(s):

H. Stapelfeldt ◽

R.E. Møller ◽

L.H. Skibsted

Keyword(s):

High Pressure ◽

Pressure Treatment ◽

High Pressure Treatment ◽

Β Lactoglobulin ◽

Kinetics Of ◽

Ellman's Reagent

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Influence of high hydrostatic pressure on the proteolysis of β-lactoglobulin A by trypsin

Journal of Dairy Research ◽

10.1017/s0022029905001664 ◽

2006 ◽

Vol 73 (1) ◽

pp. 121-128 ◽

Cited By ~ 33

Author(s):

Rosa Chicón ◽

Josefina Belloque ◽

Isidra Recio ◽

Rosina López-Fandiño

Keyword(s):

High Pressure ◽

Degradation Products ◽

Thiol Group ◽

Hydrolysis Time ◽

Structural Modifications ◽

Disulphide Bonds ◽

Free Thiol Group ◽

Β Lactoglobulin ◽

Hydrolysis Of ◽

Tryptic Hydrolysis

This work describes the effect of the hydrolysis time and pressure (0·1–400 MPa) on the proteolysis of β-lactoglobulin A (β-lg A) with trypsin, either conducting hydrolysis of β-lg under pressure or hydrolysing β-lg that was previously pressure treated. Pressurisation, before or during enzyme treatments, enhanced tryptic hydrolysis of β-lg. Trypsin degraded pressure-modified β-lg and pressure-induced β-lg aggregates, favouring proteolysis to the intermediate degradation products: (Val15-Arg40), (Val41-Lys69)S-S(Leu149-Ile162) and (Val41-Lys70)S-S(Leu149-Ile162). These were further cleaved at the later stages of proteolysis to yield: (Val15-Tyr20), (Ser21-Arg40), (Val41-Tyr60), (Trp61-Lys69)S-S(Leu149-Ile162) and (Trp61-Lys70)S-S(Leu149-Ile162). Particularly, in the tryptic hydrolysates of pre-pressurized β-lg, two other fragments linked by disulphide bonds: (Lys101-Arg124)S-S(Leu149-Ile162) and (Tyr102-Arg124)S-S(Leu149-Ile162), were found. These corresponded to rearrangement products induced by SH/SS exchange between the free thiol group of Cys121 and Cys160, that normally forms the disulphide bond Cys66-Cys160. In the light of these results, structural modifications of β-lg under high pressure are discussed.

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