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Literatur:
1.)
Enzymes and their utilization to detect heated milk. Lind, C. Lait (1927), 7 935-46. Journal written in Unavailable. CAN 23:3277 AN 1929:3277 CAPLUS
Abstract
Heated milk can be detected by the destruction or weakening of enzymes, viz., catalase test, aldehyde-reductase (Schardinger), reductase-peroxidase (Storch) or by chem. methods based on coagulation of albumin. None is infallible and a combination of tests and methods must sometimes be followed, particularly with regard to low-temp. pasteurization.
2.)
A study of certain ferments with a view to determining a method for the differentiation of pasteurized milk from raw milk. I. Reductases. Lee, R. E.; Mellon, M. G. J. Ind. Eng. Chem. (1917), 9 360-7. Journal written in Unavailable. CAN 11:8042 AN 1917:8042 CAPLUS
Abstract
Certain enzymes are classified as to distributions and reactions, and their sensitiveness to phys. and chem. agents studied as a basis for a method of detg. the sanitary condition of foods. The previous work or reductase in its relation to pasteurization of milk is reviewed. The following conclusions are drawn from the authors' work. Methylene blue, in Schardinger's reagent, F. M., is not decolored by (a) normal fresh milk in less than 20 min., (b) milk pasteurized at 70° for 10 min., until 48 hrs. after heating, (c) milk treated with HCHO. Normal "aged" milk (24-48 hrs.) will usually decolorize Schardinger's reagent. In general, there is no proportionality between time required for decolorization and the number of bacteria in the milk, but in the same sample, up to a certain acidity, there is some relation between these two factors. Apparently reductase is of bacterial origin, but not all milk bacteria produce it.
3.)
The Usefulness of the Reduction Test for Judging the Hygienic Quality of Milk. Barthel, Chr. Bakteriol. Lab. Zentralanstalt., landw. Versuchswesen, auf Experimentalfaltet, Stockholm, Z. Nahr.-Genussm. (1908), 15 385-403. Journal written in Unavailable. CAN 2:8784 AN 1908:8784 CAPLUS
Abstract
A complete historical review is given of the action of enzymes in milk in decolorizing certain coloring agents, and the effect of heating milk upon this action, and also the relation of the decolorization to the number of bacteria present. "Schardinger's reagent" was experimented with in two forms: (1) 5 cc. saturated alcoholic solution of Methylene Blue + 5 cc. formalin + 190 cc. distilled water; (2) 5 cc. alcoholic solution of Methylene Blue + 195 cc. distilled water. The influence of various factors upon the reduction of Methylene-Blue solution was studied, such as temperature, chloroform, toluene, addition of acids, etc. The relation of the test to the number of bacteria in milk was studied, using both of the above solutions. The time required to decolorize the solution was used as the basis for comparison. It was shown that the formalin-free Methylene-Blue solution was more useful than the solution containing formalin. For example, in one of the samples of milk studied, the fresh milk contained 10,000 bacteria per cc. and, at the end of 4 days, 47,500,000; the formalin Methylene-Blue solution was decolorized in 14 min. in the fresh milk and in 4 min. in the 4-day old milk; the Methylene-Blue solution (without formalin) was decolorized in 11 hrs. in the fresh milk and in 12 min. in the 4-day old milk. The test carried out in the simplest possible way is as follows: 10 cc. of the milk to be investigated are treated, in duplicate, in test tubes with 0.5 cc. of the above-described formalin-free solution of Methylene-Blue; a few cc. of melted paraffin are put on top of the liquid and the tube set in a water-bath at 40-45°. The time required for decolorization is noted. When this takes place in a few minutes, then the milk surely contains 100,000,000 or more bacteria per cc. Even in cases in which the decolorization takes place within one hour, the milk must be regarded as bacterially too impure for use as food and especially for infants. Good commercial milk should require at least 3 hrs. to decolorize the solution.
4.)
The use of 2,6-dichlorophenol indophenol as a reduction indicator in the examination of foodstuffs. Tillmans, J.; Hirsch, P.; Reinshagen, E. Univ. Frankfurt a. M., Z. Unters. Lebensm (1928), 56 272-92. Journal written in Unavailable. CAN 23:27533 AN 1929:27533 CAPLUS
Abstract
The indicator which is obtained by coupling a soln. of 5 g. of 2,6-dichloroquinone chloroimide (the prepn. of this from p-NO2C5H4OH is described) with 8 to 12 cc. of an alk. 20% soln. of phenol is very stable if stored in the form of a filtered 0.01 N (0.29%) soln. in a phosphate buffer of pH 7. The color change is from pale red to blue, between pH 4 and 5. The indicator appears deep blue in the presence of oxidizing agents and colorless with reducing agents. The reduction potential was detd. and the values at 20° against the normal H electrode were 255 and 233 mv. at pH 6.85 and 7.01. There is a fall in potential of 1 to 2 mv. for each 1° rise in temp. (C. A. 21, 29). The method was used to det. the effects of CH2O and heat on the Schardinger reaction of milk but no definite results were obtained. Attempts to apply the method to the detn. of the nature and degree of putrefaction of meat exts. (C. A. 21, 2510) also proved ineffective. Artificial lemon juice was distinguished from the natural juice by the fact that it produced no decolorization of the indicator. The probable nature of the constituents responsible for the changes taking place is discussed.
5.)
Observations on the Schardinger Reaction of Milk. Schern, Kurt. K. Wilhelm Inst. Landw., Bromberg, Biochem. Z. (1909), 18 261-84. Journal written in Unavailable. CAN 3:13514 AN 1909:13514 CAPLUS
Abstract
Tests made on a large number of cows of known history showed that the Schardinger reaction is not in all cases suited to determine the freshness, heat-denaturing, or watering; that the test should be made first at 65-70° and if here negative then at 45°. In most cases the reaction does not appear in the milk of cows a few weeks after parturition, and appears much later in that of cows that have suckled. The fresh milk of old-milking cows shows the reaction as given by Schardinger, and the amt. of Schardinger enzyme seems to increase in proportion with the time after parturition.
6.)
The Schardinger Reaction for Cow Milk. Roemer, Paul H. Marburg, Biochem. Z. (1912), 40 5-14. Journal written in Unavailable. CAN 6:13029 AN 1912:13029 CAPLUS
Abstract
The Schardinger reaction (catalysis of the reduction of methylene blue in the presence of CH2O) is unreliable for the detn. of the freshness of milk. Perfectly fresh milk often fails to give the reaction; boiled milk gives it after being rendered alk. Boiled milk to which FeSO4 has been added also gives the reaction.
7.)
The use of Schardinger's reaction to distinguish woman and cow milk. Pagenstecher, Helmut. Univ., Freiburg i. Br., Germany. Monatsschr. Kinderheilk. (1949), 97 321-7. Journal written in Unavailable. CAN 44:12915 AN 1950:12915 CAPLUS
Abstract
The reaction consists in the reduction of methylene blue to the leuco base in presence of CH2O and exclusion of air by the action of an enzyme, aldehyde dehydrase. The reaction increases, i.e. the time of reduction decreases, in cow milk on standing by spontaneous acidification, reaches a max. on the 4th day at a pH 4.4 and then decreases again. Addn. of lactic acid produces the max. on the 2nd day at pH 5.4. Pasteurized milk does not contain the enzyme. Human milk contains only traces. The reaction can serve only as a general orientation to judge whether or not a milk is suitable for infant feeding but cannot be used to distinguish reliably both types of milk. The enzyme is destroyed in the gastric juice of adults because it does not resist pH 2.
8.)
The aldehyde reducing power of milk (Schardinger reaction). Carrieu, M. F. Le lait (1921), 1 429-33. Journal written in Unavailable. CAN 16:4156 AN 1922:4156 CAPLUS
Abstract
The reagent used by C. in testing for the Schardinger reaction was: Soln. (1): 0.25 g. methylene blue in 50 cc. of 90% EtOH, 10 cc. of this soln. being mixed with 190 cc. of distd. water. Soln. (2): 0.25 g. fuchsin, in 50 cc. of 90% EtOH, 10 cc. of this soln soin. being mixed with 190 cc., distd., water. The actual test soln is compounded by measuring 50 cc. of soln. (1), 30 cc. of soln. (2) and 30 cc. of formalin. Seven to 10 drops of this mixt. are added to 20 cc. of milk. Conclusions: (1) The aldehyde reducing power is almost const. for cow milk. (2) The nature of the reducing substance is not known. (3) It is probably fixed to the fat globules. (4) Heated milk does not give the reaction but this cannot be used as a means of distinguishing between fresh and heated milk because of inconstancies with fresh milk. (5) Generally older milk shows the reaction more strongly than fresh milk (though not without exceptions). (6) The test is not sensitive to det. whether milk was remade from powder or not. (7) It is not useful for showing the presence of H2O2 in milk. (8) It is not const., for the milk of certain animals.
Die Literatur ist meistens recht alt, ich denke aber, dass man alleine aus den Abstracts einige Informationen gewinnen kann. Zu Enzymen als Biokatalysatoren leihst Du dir am besten ein Biochemie Buch wie den Lehninger aus.
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