Which one of the following is NOT used in testing for adequate pasteurization of milk?

Tests used to detect adequate Pasteurization of Milk are(sufficiency of pasteurization): - Phosphatase Test: Widely used test - Standard Plate Count: Enforced limit is 30,000 bacterial count per ml of pasteurized milk. - Coliform Count: Standard is Coliform be absent in 1 ml of milk. Methylene Blue Reduction Test : - Is an indirect method for detection of microorganisms in milk . - Blue colour disappears from milk when held at a uniform temperature of 37degC. - Milk which remains blue the longest, is of the best quality.