This article describes a simple method for adjusting the "mano variables," grind setting, coffee dose, and shot time, to achieve close to the best possible taste from any espresso blend or SO. It does not give instructions on how to adjust temperature or pressure in response to taste, nor what basket to select; instead it assumes these remain fixed. The method will not find the optimal mano variables for every coffee; but in my experience, it will get close to optimal for most.
It is addressed to intermediate baristas with enough experience to pull non-channeling shots, to stop them at a correct and consistent blonding point, to adjust their grinders and dose consistently, and to keep the pressure and temperature profiles of their machines fairly constant and within normal espresso bounds. Experienced baristas may be interested in the way this method classifies taste and mano variables, but it won't improve their skills in dialing in coffees.
The Mano Variables:
Grind setting, dose, and shot time are the actual physical adjustments a barista makes, but these do not translate well to taste changes. Instead, we need to reconceptualize the three physical adjustments into three cognitive variables that relate better to the taste (in math speak, it's doing a canonical correlation or factor analysis by rotating the axes of the variable space):
- Up/Normal/Down Dose: the dose of coffee required to either normally, over or underfill the basket, along with the grind setting required to get an intermediate shot, i.e. a double roughly 30 seconds long, 1.5 ounces in volume, 1 ounce in weight, stopped at the normal blonding point. The exact weight and grind setting needed to accomplish this will depend on type of basket, group, and grinder being used.
- Normale/Ristretto: the smaller grind and/or dose changes required to move from the settings above to either a ristretto shot, a double roughly 35 seconds long, 1 ounce in volume, 1/2 ounce in weight, stopped at the normal blonding point; or to a classic normale, a double roughly 25 seconds long, 2 ounces in volume, 1.5 ounces in weight, stopped at the normal blonding point.
- Pale/Dark stopped: Stopping shots adjusted as above earlier or later than normal, when the flow is correspondingly darker or lighter colored.
The Taste Variables:
Exact flavors, for instance, cherry or chocolate, are an aspect of the coffee itself, and cannot be altered. Neither can the specifics of the mouthfeel, the sparkle and astringency, the fine texture of the crema. However, the way these flavors and textures balance in the shot can be altered and fine tuned. As with the Mano variables, they have to be classified in a way that makes them amenable to control.
- Acids, Caramels, Bitters:
- Acids: Fruit acids and fruit sugars, along with floral and herbal aromas.
- Caramels: Chocolate, caramel, malt, and nut, along with cake baking in the oven aromas.
- Bitters: Spice, wood, sherry, and citrus peel, along with smoke, tobacco and tar aromas.
- Foamy versus Oily Mouthfeel: When ideally balanced, the crema and liquid portions of the shot are almost folded together and fairly stable over the minute or so in which the espresso is consumed. Usually, if the crema is unbalanced, either in a thin oily layer, or with a pile of large bubbles, the drink will not be as pleasant feeling on the tongue, nor will it last as long.
The Relation of Mano to Taste
- Dose and Taste Loudness: Up dosed shots emphasize both extremes, the acids and the bitters, at the expense of the middle caramel flavors. Down dosed shots do the opposite, emphasizing the caramels at the expense of the bitters and sours.
- Shot Volume and Acid/Bitter balance: Classic normales, that is faster flowing, larger volume shots, emphasize the acidic flavors. Ristrettos, that is slower flowing, lower volume shots, emphasize the bitter flavors.
- Flow Color and Mouthfeel: Allowing the shot to go longer and paler creates a lighter texture, cutting it shorter and darker creates a heavier texture. Unfortunately, ristrettos are inherently heavier textured than normales, so the timing differences need to be exaggerated in order to compensate (e.g. the ristretto may need to run to platinum blonde and almost a gush in order to have a really fine texture)
Hope this has helped.