They're fermenting the protein out of yeast, so it'll definitely be the exact same chirality as any protein in your body at the amino acid level. If you were to take the leghemoglobin extracted from a soy plant and the leghemoglobin fermented using yeast you'd essentially not be able to tell the difference. The only thing that might give it away would be some of the trace contaminants (you'd have trace soy protein versus trace yeast protein), all of which you eat/drink regularly anyway (that is if you eat soy or bread).
Full disclosure, the founder of Impossible Foods was an advisor of mine in grad school.
