Case Study Questions: 1. A common method of ensuring pasteurization of milk is t

Question

Case Study Questions:

1. A common method of ensuring pasteurization of milk is to test the activity of an enzyme called phosphatase. An adequately pasteurized milk sample will have only a very small amount (<1 ug/ml) of functional enzyme. Explain why this test can be used to determine the adequacy of pasteurization.

2. California law states that milk prior to pasteurization have no more than 750 coliforms per ml and no more than 50,000 total bacterial CFUs per ml. Assuming that 1 ml of milk is diluted into 99 ml of water and 0.5 ml of the diluted milk is used to inoculate a plate, what is the maximum number of colonies – both total and coliform – that may grow for the milk to be judged acceptable?

3. Bacteria in milk may also be detected directly, that is, by examining a small quantity of milk under the microscope and counting the number of cells present. Despite the fact that this is a very accurate method of counting cells, the FDA requires a viable cell count be performed. Why is a viable cell count a better indicator of the safety of milk (especially pasteurized milk)?

Explanation / Answer

1.Routine testing of processed fluid milk products for levels of residual ALP using the Fluorophos and the Charm systems will support

other procedures that ensure proper pasteurization. Though the cut off level of ALP is 350 milliunits/liter, the levels common in

pasteurized milk are often less than 20 due to the higher than required pasteurization temperatures commonly used. This ALP value

may vary depending on the processing conditions and the source of raw milk so it is important that each plant establishes a baseline

level of what would be considered normal ALP values for the specified processing conditions. Once a baseline ALP level is

established, routine monitoring can be used to detect processing deficiencies. If ALP activity of a sample is higher than what is

normally seen in the baseline or in previous samples, it should sound an alarm. Higher ALP activity may indicate serious deficiency in the pasteurisation process.

3.3.T Lab Pasteurized Count (LPC) estimates the number of bacteria that can survive the pasteurizationprocess. Milk samples are heated to simulate batch pasteurization at 145°F for 30 minutes. Bacteria that survivepasteurization (thermodurics) are then counted using the SPC procedure

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.