LOL, how not? Defining grades of a commodity are certainly definable as both measures and elements of interstate and international trade. Clear, defined parts of federal authority.
A measure is ounces, inches, etc. That’s clearly what was meant by “weights and measures.”
To claim otherwise is to accept the federal Leviathan’s interpretation of Constitutional terms, like “the Commerce Clause means we can regulate anything and everything.”
By the way, there is nothing stopping a state from regulating this. But it’s not part of legitimate federal authority.
The anti-Federalists were right.