I have to admit it.

I'm a victim of the 10 % rule. Meaning that I cannot consistently taste 10 % differences. With 'consistently' I mean 'from one day to the next', not from one cup to the next. Dose, extraction time, tamping force: if they stay within (roughly) 10 % of the parameters, I'm never certain if I really taste a difference (again, compared to the previous day). And I don't care about tamping anymore, so that variation probably is a lot higher than 10 %.

Temperature is one big exception. Grind maybe another, although I never measured particle size.

Now this is odd: I like to cook, and the same rule (roughly) holds for many recipes. There's hardly any difference between a cake prepared with 200 and 220 g flour. Again the big exception is temperature. A cake that comes out of the oven perfectly fine at 180 C, will be a disaster at 160 or 200 C.

I this a general rule of human physiology, or are my tastebuds worthless?

Food recipes are very inexact by and large. Small differences in many components do not generally make significant differences. My aunt used to give me recipes "with take some of this and some of that" and when pressed for details she couldn't give me. I will often mix in a couple of grams of another bean that I have for my am vac pot with my espresso. Its usually an Ethiopian or Yemeni and the variation from shot to shot technique can be more than a 1/2 gram difference. Same with adding the usual Sumatran to my pre roast espresso, 1.5 or 2.0 grams in a 9 oz roast makes no difference. Much more than 2 grams however is not to my liking. A 2 degree Fahr. difference in the pull does make a discernible difference.

Marvin

You are correct that there exist physiological limits in detecting differences, whether it is sight, sound, touch or taste (etc). While in all these there individual differences which can be quite marked, the 10% 'guesstimation' is probably reasonably accurate for most of us. Taste in particular however, is very complex, as it involves olfactory senses in your nasal passage as well as the tongue, and there are those who are very discerning in this regard (not me!).

One of the most fun things about espresso in particular is getting a bit of variation (so long as it is a 'good' variation). This way you are always looking forward to something a little bit unique. And the 10% thing helps uniformize things a bit.

Mostly you are right, but there are some knife edge parameters. Even a 0.1% addition of egg yolks will make an easily tasted difference in the whipped egg whites . The oven temperature on cake can be compensated with cook time, but changes of 5F in internal temperatures will kill cake, bread, and pork.

Espresso is similar, with some rough and some fine variables. Dose weight is the most "knife edge" parameter, even if you compensate on grind, a 1/2 gram out of 14 to 18 will change the taste in easily perceptible ways. Pressure on the other hand, is at the coarse end, with anything between 7 to 11 bar being in the ballpark, and even 1 bar changes in this range being hard to taste.

iginfect wrote:Food recipes are very inexact by and large.

Cooking, yes. Baking, no!