Oddly specific, yes. There's plenty of resources pertaining to shock therapy and analysis as to how it effected the USSR, but this seemingly simple question has seemed near impossible to answer.
Prices on these food staples were regulated by state even after January 2^nd, 1992:
Bread, milk, kefir, cottage cheese, basic types of children food (like milk formula, meat and fruit puree), salt, sugar, cooking oil and (most important, of course) vodka - see [1], page 7.
Note that wholesale prices for most important raw materials and utilities were still regulated as well: iron&steel, oil, gas, railroad transportation, electricity, hot& cold water (see [1], page 6). This added to the inflationary pressure of early 90s.
Sources