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Effect of various heat treatments on plasminogen activation in bovine milk during refrigerated storage
Author(s) -
Lu Rongrong,
Stevenson Clint D.,
Guck Shannan E.,
Pillsbury Laura A.,
Ismail Baraem,
Hayes Kirby D.
Publication year - 2009
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2008.01808.x
Subject(s) - plasmin , chemistry , plasminogen activator , cysteine , fibrinolysis , biochemistry , endogeny , food science , enzyme , medicine , endocrinology , biology
Summary Plasmin and plasminogen‐derived plasmin activities were measured in heated milk with and without the addition of plasminogen activator, before and after storage at 4 °C for 96 h. The effect of a free sulfhydryl group donor, β‐lactoglobulin or cysteine, on plasminogen activation was investigated in a model system and milk. Heating milk to 75 °C enhanced plasminogen activation that was marked by a considerable increase in plasmin activity. Heating at 85 and 90 °C caused a significant decrease in plasmin and plasminogen‐derived plasmin activities. However, after storage, significant plasmin levels were restored because of the activation of remaining unfolded plasminogen. Both β‐lactoglobulin and cysteine significantly decreased plasmin and plasminogen‐derived plasmin activities in a model system. While endogenous β‐lactoglobulin was not sufficient to completely eliminate plasminogen activation in milk, cysteine addition prior to pasteurisation significantly decreased plasmin and plasminogen‐derived plasmin activities. Results highlighted the importance of the remaining plasminogen in heated milk systems.