I had two cartons of half and half in the fridge, neither had reached its expiration date but one was three days newer. I wondered if I could taste the difference between them, and I found that I could. Neither was sour, but one tasted fresher. I made a batch of vanilla ice cream out of each of them, figuring that together with the other ingredients I was adding (vanilla, egg yolks, cream, salt and sugar) the difference in taste would be less noticeable. After putting both mixtures through the ice cream freezer I tasted them [side by side] and one tasted a lot better. I gave a friend of mine a spoonful of each and she immediately noticed the difference. She correctly identified the good one and described it as tasting fresher and lighter. I can’t bear to eat the less good batch and I don’t know what to do with it. I don’t want to give it away for fear someone will think it representative of what my ice cream tastes like. I’m sure in the past I’ve made plenty of ice cream of this same quality that I and everyone else thought was perfectly acceptable, even delicious.
The fascinating part is “can’t bear to eat the less good batch”. Same thing with me and tea: In the last half year or so, I’ve made hundreds of side-by-side comparisons of tea. I now throw away cups of tea I don’t like. I never used to do that.