A Study of the Reducing System of Milk

Gould, I.A.

doi:10.3168/jds.s0022-0302(40)95583-7

Cited by 10 publications

(1 citation statement)

References 13 publications

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“…Several methods of studying the SH groups of milk have been published, and in view of the influence of reducing conditions on reactivation, some of these methods (4,5,6) were applied to milk from this particular farm. No significant differences were found between those milks giving good reactivation and others giving poor reactivation.…”

Section: The Figures Inmentioning

confidence: 99%

535. Reactivation of milk phosphatase following heat treatment. III

Wright¹,

Tramer²

1954

Journal of Dairy Research

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1. Of a number of farm milks examined, two have been found to develop a positive phosphatase reaction following pasteurization at 161° F. in a small H.T.S.T. plant. This phosphatase was not of bacterial origin but was reactivated milk phosphatase.2. Considerable variation in reactivation following pasteurization at 161° F. was found to occur using individual churns of the above farm milk from any one milking. Individual cow samples also showed similar variation when tested by the capillary method. No explanation of this variation is offered.3. Commercial bulk raw milk from road or rail tanks did not develop a positive phosphatase reaction after pasteurization at 161° F. on this plant.4. Cold storage of pasteurized milk susceptible to reactivation results in less reactivation, and some evidence was obtained that cold storage of the corresponding raw milk also results in less reactivation. No such effect has been observed either using the capillary method or with samples of Uperized milk.5. Pasteurizing at 170 and 180° F. usually resulted in increased reactivation as compared with that obtained after pasteurization at 161° F. Shortening the holding time at these two higher temperatures sometimes led to a further increase in reactivation.6. It is shown that no clear relationship exists between the results obtained by plant pasteurization and the capillary method.7. It is suggested that many of the reported cases of pasteurized cream developing a positive phosphatase reaction on storage can be attributed to reactivation of the enzyme.8. Practical implications of reactivation in relation to pasteurized milk are discussed.

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Section: The Figures Inmentioning

confidence: 99%

535. Reactivation of milk phosphatase following heat treatment. III

Wright¹,

Tramer²

1954

Journal of Dairy Research

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�ber eine potentiometrische Bestimmung der Sulfhydrylgruppen in Milch

Kiermeier

Petz

1966

Z Lebensm Unters Forch

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A Colorimetric Method for the Estimation of Reducing Groups in Milk Powders

Chapman¹,

McFarlane²

1945

Can. J. Res.

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A method has been developed for the detection and estimation of certain reducing groups in milk powders. The method is based on the reduction of potassium ferricyanide at 70 °C. and pH 5 and colorimetric estimation of ferric ferrocyanide. Titration with 2,6-dichlorophenolindophenol or potassium iodate failed to show any difference between fresh and stale milk powders. In contrast the ferricyanide test indicates much higher values in fresh powders than do the titration methods, and it also reveals a marked increase in samples that have developed stale, musty odours and flavours. Lactalbumin and casein show reducing activity that increases on heating. Of the amino acids tested, only tryptophane gives a positive reaction. It is concluded that the reducing groups are present in the protein molecule and become accessible on denaturation.

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A Study of the Reducing System of Milk

Cited by 10 publications

References 13 publications

535. Reactivation of milk phosphatase following heat treatment. III

535. Reactivation of milk phosphatase following heat treatment. III

�ber eine potentiometrische Bestimmung der Sulfhydrylgruppen in Milch

A Colorimetric Method for the Estimation of Reducing Groups in Milk Powders

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