The reference to the "reserve test", here and in other article, seem to relate to the concentration of acid or alkaline to determine how dangerous they might be.
If this is the case, then this should be the proper translation to the "reserve test".

abstract of an article that may show a better reference to the same phrase:
http://www.informaworld.com/smpp/content~content=a777312600~...

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Note added at 10 hrs (2008-06-21 18:34:24 GMT)
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I am not sure that the two things are that different. pH is not something one measures. When you test chemical material for acid or alkaline, you test existance of certain ions. if you have a lot of acid ions, the pH is lower than 7 and the material is acidic; if you have alkaline ions the pH is higher than 7 and the material is alkaline.
When combining acidic ions and alkaline ions together, they react and neutralize each other. Perhaps this Reserve Test, as Shai said, is there to check what's left after such reaction - whether the material became acidic, alkaline or neutral.

From the context that you provided this test is intended to quantify the PH level of a product. Each product contain different levels of acidic material and alkaline, Acid is causing the PH to be lower (more acidic) and alkaline causing the PH top be higher (less acidic). Acid and Base reacts together and "cancel" the effect of each other, the reserve test does not deal with the concentration of both types of compounds but with what is left after the acid and base have reacted. Meaning that in the end it just measuring the PH level - what is the acidic level of the product and according to the context you provided on this basis the product get classified.

If the term titration is used in this context it means that during the test there is unknown concentration of an acid or a base, and by adding known amount of base or acid (respectively) you can find out what is the molar concentration of the unknown acid or base.

I'm not sure that this is the case here. From what I understand from the context the text deals with measuring the acidic level of the product and its classification on this basis. If so I would use בוחן דרגת חומציות or בוחן PH and as a second option just leave it as alkaline reserve test

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Note added at 10 hrs (2008-06-21 18:50:10 GMT)
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The PH level test and the alkaline Reserve test are two similar but different things. The PH test measure the acidity or alkalinity level of a solution. From what you posted I thought the the product gone this test in order to quantify it's PH level. But now I see what you are refering to.
In a similar way to titration you soak a sample that contain an unknown percent of alkaline in water (or other buffer) and than measuring the amount of acid needed to neutralize it. This way you can find out what its the percent of alkaline in the sample. Note that this method does not measure the volume, concentration, or weight if the alkaline compound, but the PERCENT of it (of course you can calculate all the other measure on this basis). I don't think that this has an official name in Hebrew so you can just leave it as or use מאגר בסיס or מאגר אלקאליין. It means what amount of reserve the material (and even the human body) is having, and what its capability to withstand the formation of and the acidic nature of some situations. Or simply just the alkaline content (generally in units of percent) of the sample.

I hope that this is more clear now.