Bubbly Drip Coffee = Poor Quality?

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After visiting several coffee shops over the past few years, it seems that bubbly coffee has a poor quality associated with it.

If it's a pump-press pour (as opposed to a waterfall or spicket pour), this seems to exacerbate the bubble effect... So I'm not sure if it's as much the pouring method or the quality of the coffee itself.

Does anyone have any ideas as to what causes this aeration/bubble effect and whether or not this bubble-to-quality ratio is legit or something of my imagination?
 

Noodlz2

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If frothy urine suggests a soaping effect in the body, as Peat has mentioned in the past, I wouldn't be surprised if this represents something similar

I also feel like I may be tasting soap when my coffee is too bubbly. May just be imagining it though.
 

Aaron

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I only drink coffee with the crema because this is the most reliable indicator that it's fresh and of good quality. Coffee with bubbles never seems particularly fresh or good. Then again, I've switched to tea and will only drink coffee when it's of exceptional quality.
 
OP
Twohandsondeck
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If frothy urine suggests a soaping effect in the body, as Peat has mentioned in the past, I wouldn't be surprised if this represents something similar

I also feel like I may be tasting soap when my coffee is too bubbly. May just be imagining it though.

I've never considered the action of soaping. I suppose this is to mean that fat is being emulsified by soap and this visually appears as bubbles(?)

I only drink coffee with the crema because this is the most reliable indicator that it's fresh and of good quality. Coffee with bubbles never seems particularly fresh or good. Then again, I've switched to tea and will only drink coffee when it's of exceptional quality.

Ah yeah, that's a fair point. Crema does seem to be the antithesis of bubbles. Interesting thought comparison.
 

Noodlz2

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Crema seems to be caused by oil left on the bean. I would imagine the oil is mostly unsaturated, but it probably contains the bulk of the vitamin E as well.

I feel like I dislike oily coffee, but I haven't head enough coffee with crema to tell.
 

Noodlz2

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I've never considered the action of soaping. I suppose this is to mean that fat is being emulsified by soap and this visually appears as bubbles(?)

Soap bubbles, surfactants, detergents

Not too sure, but this link seems to suggest that soap alters water's surface tension. The reduced tension plus the inclusion of air (for example, from peeing or pouring a liquid from up high) can cause bubbles to form. So if you see a liquid form bubbles with some agitation (like pouring from height), then it suggests the presence of soap. They also mention that bubbles form without soap as well, but they quickly pop. Only soapy bubbles stick around for a while.

Not sure what the relation to fat is, other than that soap is commonly made with fat. Maybe fat is a necessary component of soap, and a soaping action suggests fat involvement somewhere upstream. For example, if frothy urine is connected with high stress hormone production, the fatty acid oxidation involved in the stress response may manifest in frothy urine.
 

Noodlz2

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I seem to get bubbles from just taking non bubbly coffee and pouring it into a different cup from up high. Bubbles probably don't indicate soap or quality I think lol.
 

inthedark

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Espresso crema is trapped gases and coffee solids. Next time you get an espresso scoop a bit of crema off the tops and taste it. It's quite unpleasant by itself, and leaves a grainy mouthfeel, but can play well with the flavours in rest of the espresso. But the idea that it's an indication of quality or even freshness is a myth. Many home espresso machines make fake crema by forcing the espresso through a pinhole under the basket. It can be an indication of roast level, and also certain varieties of coffee may produce more crema than others when prepared as espresso. Darker roast coffees do tend to produce more crema, and maybe this does have to do with the rancid oils on the outside of the bean being emulsified as the espresso is extracted.

As for bubbles, it is possible that actual soap or detergent is making its way into the coffee. Some coffee shops do not properly clean and or rinse coffee making equipment. Detergents are used to clean off the buildup of oils and solids in espresso machines and drip coffee makers, and if these detergents are used in excess or not properly rinsed off afterwards this could easily be present in the coffee. If the bubbles look soapy I'd say find a new place to get your coffee.
 

Noodlz2

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Espresso crema is trapped gases and coffee solids. Next time you get an espresso scoop a bit of crema off the tops and taste it. It's quite unpleasant by itself, and leaves a grainy mouthfeel, but can play well with the flavours in rest of the espresso. But the idea that it's an indication of quality or even freshness is a myth. Many home espresso machines make fake crema by forcing the espresso through a pinhole under the basket. It can be an indication of roast level, and also certain varieties of coffee may produce more crema than others when prepared as espresso. Darker roast coffees do tend to produce more crema, and maybe this does have to do with the rancid oils on the outside of the bean being emulsified as the espresso is extracted.

As for bubbles, it is possible that actual soap or detergent is making its way into the coffee. Some coffee shops do not properly clean and or rinse coffee making equipment. Detergents are used to clean off the buildup of oils and solids in espresso machines and drip coffee makers, and if these detergents are used in excess or not properly rinsed off afterwards this could easily be present in the coffee. If the bubbles look soapy I'd say find a new place to get your coffee.


Thanks Rick. I think a rainbow glare/sheen on the bubble suggests that it is soapy vs just a normal bubble.
 

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