Effects of adding potassium iodate to milk before UHT treatment: II. Iodate-induced proteolysis during subsequent aseptic storage

Skudder, Paul J.

doi:10.1017/s002202990002152x

Cited by 10 publications

(12 citation statements)

References 21 publications

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“…The exact mechanism of thermal denaturation of the serine proteinases PA with β-lactoglobulin remains unknown, but S-S/S-H interactions similar to those already described for the serine proteinase plasmin [31] could be involved. In agreement, considerable PA activity was apparent after heat treatment of a high somatic cell count milk in the presence of the oxidizing agent KIO 3 [23] which is known to inhibit the effect of SH-containing whey proteins like β-lactoglobulin during the heating process [13,43].…”

Section: Influence Of -Lactoglobulin On Thermal Inactivation Of the Isupporting

confidence: 58%

Heat inactivation of native plasmin, plasminogen and plasminogen activators in bovine milk: a revisited study

Denis¹,

Humbert²,

Gaillard³

2001

Lait

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Thermal inactivation, at temperatures between 60 o C and 140 o C, of native plasmin, plasminogen and plasminogen activators were studied in bovine milk using improved enzymatic assays. While measured heat inactivation kinetic of plasmin and plasminogen were in line with previously reported values, plasminogen activators were, surprisingly, found to be as heat sensitive as plasmin and plasminogen in a milk system containing proteins with free SH groups. Activation energies (Ea) for the heat denaturation of plasmin, plasminogen and plasminogen activators were 29, 35 and 24 kJ. mol-1 , respectively, in the temperature range 95-140 o C , and 244, 230 and 241 kJ. mol-1 , respectively, in the temperature range 70-90 o C. The heat inactivation of the whole plasmin system in milk appeared to be directly influenced by the presence of β-lactoglobulin. The rate of plasmin inactivation during long heat treatments decreased rapidly, probably because of the disappearance of available β-lactoglobulin for S-S linking. plasmin / plasminogen / plasminogen activator / heat inactivation / milk

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Section: Influence Of -Lactoglobulin On Thermal Inactivation Of the Isupporting

confidence: 58%

Heat inactivation of native plasmin, plasminogen and plasminogen activators in bovine milk: a revisited study

Denis¹,

Humbert²,

Gaillard³

2001

Lait

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“…Addition of 01 niM-KI0 3 to milk before UHT treatment resulted in rapid breakdown of the caseins during storage at 37 °C, whereas the other oxidizing agents studied, H 2 O 2 , KMnO 4 and K 2 Cr 2 0 7 , had no effect even though the redox potentials of these oxidizing agents are higher than that of iodate. Skudder (1981) found that KI0 3 , NaI0 3 and KIO 4 were the only additives which accelerated proteolysis of casein during storage of milk samples subjected to simulated UHT treatment; KBrO 3 , NaClOg and KI had no effect. The special oxidizing power of KI0 3 has been .…”

Section: Resultsmentioning

confidence: 92%

“…A simulated UHT treatment, similar to that described by Skudder (1981), was used. Quantities of milk or casein samples (50 fi\) were placed in melting-point capillary tubes (100 mm long, 0-9-1-0 mm diam.…”

Section: Processing and Storage Of Samplesmentioning

confidence: 99%

“…a sl -Casein, a s2 -and especially /?-casein are susceptible to proteolysis by MPA (Noomen, 1975;de Rham & Andrews, 1982;Andrews, 1983;Andrews & Alichanidis, 1983), but /c-casein is very resistant (Eigel, 1977). Skudder et al (1981) and Skudder (1981) showed that addition of KIO 3 to milk before UHT treatment resulted in rapid breakdown of a sl -and /?-caseins during storage. The latter suggested that this was due to a milk proteinase other than MPA or Pseudomonas proteinases, since KIO 3 had no effect on the proteolytic activity of these enzymes when they were added to milk before UHT treatment.…”

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confidence: 99%

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Potassium iodate-induced proteolysis in ultra heat treated milk during storage: the role of β-lactoglobulin and plasmin

Grufferty

Fox²

1986

Journal of Dairy Research

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SummaryThe report that addition of KI03 (0·1 mm) to milk before ultra high temperature (UHT) treatment induces extensive proteolysis during subsequent storage at 37 °C was confirmed. None was produced by addition of H202 KMn04 or K2Cr207. The pH optimum for KI03-induced proteolysis was between 7·0 and 8·0 and the temperature optimum 37—45 °C. β-Casein was particularly susceptible and the proteolysis pattern was similar to that caused by indigenous alkaline milk proteinase (MPA, plasmin). Addition of plasmin to milk before UHT treatment (140 °C/10 s) caused slight proteolysis during subsequent storage but addition of 0·1 mm-KI03 and plasmin caused extensive proteolysis which was prevented by addition of soyabean trypsin inhibitor, indicating the probable involvement of plasmin in KI03-induced proteolysis in UHT-treated milk. Equally extensive proteolysis occurred in serum protein-free casein micelle systems (SPFCM), with or without KI03, during storage at 37 °C following UHT treatment, indicating a role for whey proteins in KI03-induced proteolysis. Addition of β-lactoglobulin (β-lg) to a SPFCM system inhibited proteolysis, but extensive proteolysis occurred in a SPFCM system containing both β-lg and KI03. MPA-free Na caseinate (prepared by heating at 140 °C for 7 min) underwent extensive proteolysis when treated with plasmin before UHT treatment; proteolysis was inhibited by addition of °-lg to this system and KI03 reversed the inhibitory effect of β-lg. Plasmin proteolysis of isolated αs1-casein was inhibited by denatured β-lg (90 °C/30 min) at a level of 4 mg/ml but not by native β-lg. When denatured in the presence of KI03, β-lg had a lower free SH content than the control and was less inhibitory for plasmin in proteolysis of isolated αsl-casein. The results show that denatured β-lg inhibits plasmin proteolysis of caseins in UHT milk and that inhibition is prevented by KI03. This inhibition may occur via thiol–disulphide interchange, which is prevented if the SH group of ²-lg is oxidized by KI03, thus permitting the stimulatory effect of KI03 on proteolysis in UHT-treated milk.

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“…Thus measurement of plasmin activity has become necessary in milk and dairy products. Different methods have been used in attempts to quantify the enzyme, such as electrophoresis (Driessen & Van der Waals, 1978;Eigel et al 1979;Skudder, 1981;Andrews, 1983), 14 C-radiolabelling and chromatography (Barry & Donnelly, 1981), colorimetric measurements of the breakdown products (de Rham & Andrews, 1982) and use of artificial substrates (Reimerdes et al 1979). Two simple and sensitive methods have recently been described using chromogenic (Rollema et al 1983) or fluorogenic tripeptides (Richardson & Pearce, 1981).…”

mentioning

confidence: 99%

Variation with season and lactation of plasmin and plasminogen concentrations in Montbeliard cows' milk

Benslimane

Dognin-Bergeret

Berdagué

et al. 1990

Journal of Dairy Research

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Plasmin and plasminogen were determined monthly over a one year period in samples of bulk and herd milks from Montbeliard cows. Montbeliard milk showed a high content of plasmin and plasminogen in comparison with milk from other breeds. In bulk milk, the plasmin activity reached a minimum in September (015/tg/ml milk) and a maximum in June (032/ig/ml milk). The annual mean concentration was 0-23 /ig/ml milk. The plasminogen content varied around a value of 1-28 /tg/ml milk, with a marked decrease in September (0-83 /ig/ml milk) and a maximum in October (l -59 /tg/ml milk). In herd milk, the minimum plasmin activity occurred in October (0-17 /ig/ml milk) and the maximum in spring (0-42 fig/'ml milk in May) with an annual mean of 0-30 /tg/ml milk. The plasminogen content varied in a similar way, from 0-87 fig/ml milk to 1'82 /tg/ml milk, with an annual mean of 1-46/tg/ml. The ratio plasminogen: plasmin ranged from 1-4 to 9-2 with an average of 4-9. From early to late lactation, plasmin and plasminogen concentrations increased from 0-25 to 0-38 /tg/ml milk and from 1-07 to 2-01 fig/m\ milk respectively and the plasminogen: plasmin ratio increased from 4-5 to 5-3. Studies of milk from cows at similar stage of lactation within a single herd have shown the necessity for distinguishing between two phases in the early stage of lactation. The first, a very early period, is usually present up to one month and the second occurs in the second and third months. Milk samples with the highest proportion of -y-caseins were not those with the greatest plasmin content but were those with high plasminogen contents, which had increased suddenly from the levels of the preceding month. This suggests a role for the plasminogen activator and inhibitor system.

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Effects of adding potassium iodate to milk before UHT treatment: II. Iodate-induced proteolysis during subsequent aseptic storage

Cited by 10 publications

References 21 publications

Heat inactivation of native plasmin, plasminogen and plasminogen activators in bovine milk: a revisited study

Heat inactivation of native plasmin, plasminogen and plasminogen activators in bovine milk: a revisited study

Potassium iodate-induced proteolysis in ultra heat treated milk during storage: the role of β-lactoglobulin and plasmin

Variation with season and lactation of plasmin and plasminogen concentrations in Montbeliard cows' milk

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