Phosphatase Reactivation in High-Temperature, Short-Time Pasteurized Cream

Fram, Harvey

doi:10.3168/jds.s0022-0302(57)94695-7

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…Regeneration is usually dependent on the conditions of storage. Fram (1957) found alkaline phosphatase regeneration to be accelerated by temperature and to increase with time. However, while the results showed more regeneration at 86°F than at 3&40"F, there was a decrease in residual activity during.…”

Section: And Discussionmentioning

confidence: 98%

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Stability of Spinach Catalase.

Sapers¹,

Nickerson²

1962

Journal of Food Science

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SUMMARY The effects of certain variables on the thermal stability of spinach catalase were investigated with model systems. The rate of thermal inactivation of spinach catalase was accelerated as heating temperature was increased. Inactivation kinetics were not first‐order with solutions of the purified enzyme between 50 and 60°C and with spinach extracts at 55°C, hut became first‐order with the latter preparation as the temperature was increased to 65°C. The presence of a heat‐labile catalase inhibitor is postulated. Catalase was more thermostable in spinch extracts than in solutions of the purified enzyme. Purified spinach catalase at 55°C was more thermostable in solutions at pH 5.5 and 7.0 than at pH 9.0. The thermostahility of purified spinach catalase was not influenced by the enzyme concentration or by the presence of 1.5% NaCl, 3.6% sucrose, or 3.6% starch in pH 7.0 solution at 55°C.

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Section: And Discussionmentioning

confidence: 98%

“…It can also be seen that regeneration at pH 7.0 was substantially greater when samples were heated at 62°C than at 50°C. Fram (1957) and Zoueil and Esselen (1959) have ing conditions are employed. According to Lumry and Eyring (1954), with rapid heating, the relatively slow and irreversible aggregation reactions do not become limiting.…”

Section: And Discussionmentioning

confidence: 99%

Stability of Spinach Catalase.

Sapers¹,

Nickerson²

1962

Journal of Food Science

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Dairy Products

DAVIS¹

1968

Quality Control in the Food Industry

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The reactivation of milk alkaline phosphatase after heat treatment

Lyster¹,

Aschaffenburg²

1962

Journal of Dairy Research

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A simple system was developed, consisting of a solution of jS-glycerophosphate, jS-lactoglobulin and magnesium ions, in which alkaline phosphatase isolated from milk became strongly reactivated following heat treatment for 45 sec in boiling water. From 10 to 30% of the original enzyme activity reappeared after incubation at 37 °C. Variations in the components of the system, and factors affecting it, were studied. Salts of Hg, Zn and Cd inhibited reactivation at low concentrations.Milk which, after the same heat treatment, became reactivated to a much smaller extent (about 1 %), was found to contain a dialysable, heat labile inhibitor whose presence is thought to be largely responsible for the low level of reactivation, though other factors, e.g. the suboptimal concentration of phosphate esters must be considered as contributory causes.Milk contains also a non-dialysable, heat stable activator of the reactivation process, capable of replacing /Mactoglobulin in the simple system and active at very low concentration, e.g. 0-2% (v/v).When milk or cream is exposed briefly to high temperatures, cooled and stored, the alkaline phosphatase activity, which is absent immediately after heating, tends to reappear. The conditions under which reactivation occurs have been studied by Wright & Tramer (1953a, b, 1954, 1956), Fram (1957a and McFarren, Thomas, Black & Campbell (1960). Reactivation has been observed after heating milk to temperatures ranging from 82 °C, and cream from 74 °C to 180 °C for times varying from a few seconds to a few minutes and after subsequent storage at between 5 and 40 °C. The effect is not due to bacterial growth. Reactivation does not occur in milk that has been pasteurized by the accepted H. T. S. T. process [161 °F (71-7 °C) for 15 sec], so that the efficacy of that treatment can be controlled by the phosphatase test. With cream, however, the application of this test presents difficulties since more severe heat treatment of this product is often favoured and since cream has been observed to become reactivated after being heated to as low a temperature as 74 °C.Milk is a complex medium, and in the hope of clarifying the nature of the processes involved in reactivation we have prepared alkaline phosphatase in a highly purified state and studied its reactivation both in systems simpler than milk and in milk itself.

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Phosphatase Reactivation in High-Temperature, Short-Time Pasteurized Cream

Cited by 6 publications

References 3 publications

Stability of Spinach Catalase.

Stability of Spinach Catalase.

Dairy Products

The reactivation of milk alkaline phosphatase after heat treatment

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