I'm doing a research on bromelain enzymatic activity in simulated gastric fluid (and also presence of other proteases). I've read up on previous In Vitro Study of Bromelain Activity in Artificial Stomach Juice and Blood, which referred to Milk Clot Unit assay by Balls et al (1937), and thus I read up on the MCU assay as summarized Enzyme Development Corporation. What I'm not entirely sure, is:

1. How do I perform the Milk Clotting Unit assay in simulated gastric fluid?

2. In the summary of MCU assay by EDC, I am to "allow at least two tubes for each enzyme sample". What's the two tubes for? Duplo analysis?

3. What is "assigned by lot"? Pardon me about this, since I'm not a native English speaker.

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