For those of you who are questioning the "old-fashioned" sour cream with today's commercial sour cream, I have a couple of thoughts:
1. Check the ingredients list on whatever sour cream you buy. Most of them have a bunch of chemicals, added enzymes, etc. Also, there is low fat sour cream and fat free sour cream, whatever that may be. You can't have cream without milk fat, and I can't see how that stuff could act or taste like the real thing. I buy sour cream that has only cream and maybe salt in it.
2. Old recipes calling for sour cream or sour milk was actually "soured" as previously mentioned. This was cream or milk that got sour all by itself, not really spoiled or "bad". Occasionally, in the "old" days, I had milk that went sour on me - just perfect for delicious homemade chocolate cake.
3. In my grandmother's day, refrigeration was not the best and milk and cream just naturally went sour and was used for cooking.
4. Also, milk products may have been "raw" (not pasteurized or homogenized}, the milk fat was not removed and vitamins and stabilizers weren't added, etc.
5. Farm animals were raised and fed differently than they were in the "old" days and that made a big difference in how things tasted. Meats, chicken, eggs, butter, etc. all tasted better then. Have you ever made turkey soup from the bones leftover from Thanksgiving turkey? It used to be the best soup you ever had. Try it today. It has absolutely no taste unless you add fresh turkey parts and/or bouillon. It's all in the feed and chemicals used to make the animals grow bigger and faster.
There have been lots of changes in the food we buy today. I don't know if that's good or not. I guess there are things to be said for both sides of the question, but it's no wonder today's products taste different. I guess we really can't expect grandma's recipes to turn out like they did for her. What a shame.