"sf" > wrote in message
>>
> It's the soured vs sour part that's an issue. There seems to be a
> difference and I have no idea what it is.
>
> --

We use the term "sour" when things go bad or taste tart as opposed to sweet.

Commercial sour cream fits a particular definition.
Lactic acid-producing bacteria is added to cream to produce the slightly
tart, thick sour cream. Food and Drug Administration standards dictate the
butterfat content may not be less than 18 percent for products labeled as
sour cream.

Commercial sour cream may also include rennet, gelatin, flavoring agents,
vegetable enzymes, sodium citrate, and salt. Check the label if you suffer
from food allergies

From Wikipedia
Sour cream is a dairy product rich in fats obtained by fermenting a regular
cream by certain kinds of lactic acid bacteria.[1] The bacterial culture,
introduced either deliberately or naturally, sours and thickens the cream.
Though only mildly sour in taste, the name stems from the production of
lactic acid by bacterial fermentation, sometimes referred to as "souring"..