Due to a health department code change, we are required to record the pH of our sushi rice. Meters cost hundreds of dollars. Do we really need something like that?
– Emi Shindo, Owner, Robata of Tokyo, Allentown, PA
Because sushi is best made with rice slightly warmer than room temperature, and restaurants make the sushi over a full meal service, health departments have been cracking down on time and temperature abuse of sushi rice. It is not uncommon to see sushi rice held in the danger zone for several hours.
Sushi rice is acidified with vinegar, so it does inhibit microbial growth. The guideline for most municipalities is that the pH (a test of acidity or alkalinity) of the rice be below 4.6. In some cases, a full HACCP plan for sushi is required. In others, the pH is simply subject to testing by the health department. In your case, it seems the health department is requiring a record of hold times and pH levels.
Testing pH can range from dipping a test strip into a puree of the rice (swabbing the outside of the rice grains won’t be as accurate) to using, as you note, a very accurate and expensive meter. While expensive pH meters have their place in food science and molecular gastronomy, for your purposes, you simply need to test whether your rice falls under the limit. For that kind of testing, inexpensive test strips or a low-cost meter should be fine. Just double check with your heath inspector so there are no surprises.