Friday, May 29, 2009

Brew temperature

Question

Dear Dr Brew,
Does the BUNN Home Brewer heat to a consistent 200 degrees all the way through the brew for proper extraction? Let me know, I would like to recommend it if it does, and get one for myself. Or, if you know how I can get properly extracted coffee at home, let me know.

Thanks so much

Bruce
Owner
Olson Coffee Roasters Inc

Answer

Dear Bruce,

The ideal temperature range for brewing coffee with the drip method is 195 - 205 degrees Fahrenheit. BUNN home units are designed to maintain brew temperature within this range.

The most critical phase of the brew cycle is the beginning and middle portion for brew temperature. Check out a previous response to see the brew phases. The Specialty Coffee Association of America (SCAA) recommends the temperature in the basket stays within the temperature range mentioned above during normal operation for at least 90% of the contact time between the water and the coffee grounds. The water contact temperature is measured in the center of the filter on the surface of the coffee.

I prefer to place a thermal couple in a spray head opening when measuring temperature of the brew water. This removes the variable of how the ground coffee was stored (some keep their coffee in the freezer or refrigerator).

Happy Brewing,
Dr. Brew

Wednesday, May 27, 2009

Temperature concerns

Question

Dear Dr. Brew,

Hope you are well. We are contacting you to know if there’s a possibility in a ... U3 to adjust the temperature of the coffee without take off the quality of the coffee. We know that it has a thermostat that can be adjust(ed), but we need to know if there is a another possibility to do it.
Thanks for your help.

Jorge Solano

Answer

Jorge,

The brewed coffee in this type of unit is maintained by the heated water in the main tank that surrounds the coffee reservoir. The holding temperature can not be reduced without altering the brew temperature. Normal brew temperature is 195-205o F (92 - 96o C). I suggest checking the temperature of the water reservoir and reducing it to the lower end of the range. Brew a sample coffee to assure that you still have a brew that meets your taste profile.

Happy Brewing,

Dr. Brew


Monday, May 18, 2009

Bad taste

Question

Dear Dr. Brew,

I have a small coffee shop. We have a brewer that has the most horrible taste in it. We have other things hooked up to the water source and have no problems with that, however the BUNN brewer (plumbed in to the water source) from both the water valve, and the coffee brewer taste awful.

This machine sat for a while and I have run numerous batches of coffee and fresh water through it, but I can't get rid of this taste. Is there something I missed when cleaning it and hooking it up? Advice would be greatly appreciated.

Deanna

Answer

Deanna,


It's hard to say what may have happened while the unit was stored. I would suggest taking the unit to an authorized service center. They will be able to dissasemble the unit and clean the tank. You may ask them to examine and clean the internal plumbing lines as well. I am not sure if the unit was stored with water remaining in the tank. I would suggest always draining the unit before storage.

Happy Brewing,
Dr. Brew


Friday, May 15, 2009

Dilemma with decaf

Question


Dear Dr. Brew,

We have a customer with a BUNN Dual Soft Heat brewer and interface G9 grinder. They recently switched from using a Swiss Water Decaf coffee to a Natural Decaf. However, the grounds are now overflowing the filter when we brew the Natural Decaf (either side). We don't wish to coarsen the grind and alter the regular coffee, so we tried an -078 sprayhead and lowered the throw, but it's not an ideal solution. I know with a more advanced digital brewer we could program pre-wetting and extend the pulse, but what is the workaround with this wonderful analog Soft Heat brewer?

The water here is very hard, and the customer has a softener, and we also use a BUNN Taste/Odor/Lime filter for the brewer. The brew water shows 7 grains of hardness on my test strip. I welcome your suggestions!


Mike
Leelanau
Coffee Roasting Company

Answer

Dear Michael,

Brewing decaffeinated coffee has always been a challenge compared to the regular counterpart. Adding a water softener only increases the annoyance of long brew cycle times and no filter margin or overflow of grounds in the funnel. You mention the "brew water" measuring 7 grains of hardness (1 grain = 17.1 mg/L or PPM). Is this after the water treatment systems or from the main water supply? Is the overflow only occurring on the largest batch size or does it happen for all three volumes?

You mentioned changing to a slower flow rate spray head and reduced weight -- did you maintain your water-to-coffee weight ratio? I need to do some research from my end to understand the effects of softened water and using a lime sequestering filtration system together. As you can tell, this time I have more questions than you.

To Be Continued

Happy Brewing,
Dr. Brew


Oily film on Coffee

Question

Dear Dr. Brew:

I recently posed the oily coffee question to the Tennessee Division of Water Supply and received the following explanation I thought you might find interesting:

"The Division of Water Supply has received your email regarding an oily substance that appears in your coffee and tea. From your email, it appears that the oily film is caused by the hardness of the water. The attached .pdf file explains the reaction of hard water and coffee. It is similar with tea as well."

The .pdf file (which I have lost) from Chemical Technology and Consulting explains that the calcium in hard water binds with the fatty acids that are released from the coffee during brewing (see transcription below). The lower calcium levels in soft water don’t have this effect which explains why coffee/tea that I brew with bottled water doesn’t produce the oily film. I’m currently in the process of trying to determine which type of water softener is the best to effectively solve this problem in a cost effective, reduced labor manner.:)

Explaining the Oily Film Observed on Coffee. Coffee beans naturally contain coffee oil up to 15% on a dry basis. This coffee oil is comprised of approximately 71% fatty acids or, in other words, oils much like those which would be found in margarines or soaps. These fatty acids contain a hydrophilic area and a hydrophobic area. Because they contain a hydrophilic area, fatty acids are somewhat soluble in water. When water is poured through ground coffee, this naturally occurring coffee oil is dissolved into the water and is carried to the pot which stores the coffee. Here, the oil may remain dissolved and pass unnoticed. This usually the case when the water used is of low hardness. When the water is hard, however, calcium bonds with fatty acids to precipitate them, even though they are usually soluble. Hot water from the coffee maker helps this bond to form more readily, and thus, the precipitated oil is even more pronounced.

A good analogy is soap. Much like the soap molecule, which is sodium or potassium salt of a long chain carboxylic acit (fatty acid), hard water calcium substitutes with the sodium or potassium to form the insoluble scum. In coffee, there is no substitution, but the calcium simply bonds to the fatty acid. The (CH3)(CH2),COOH+Ca2 is the oily film seen on the coffee. It is also the soap scum seen in bathrooms after calcium has bonded with the fatty acid chains in the soap. This is seen in hard water because there is enough calcium present to precipitate the fatty acids. Soft water does not contain enough calcium to precipitate fatty acids. In general, the use of very hard water increases the oily film formation seen on coffee. I hope that you and your readers find this information useful.

Sincerely,
Diane, Watertown, TN

Answer

Diane,

Thank you for providing a valuable source of information for coffee lovers everywhere. I had responded to a previous writer and listed a few of the causes directly from the coffee side. I had mentioned that water quality could certainly be one of the issues. Thanks for providing your research to answering coffee issues.

As Red Green would say, "We are all in this together."

Happy Brewing,
Dr. Brew


Wednesday, May 13, 2009

Evaporation quandry

Question

Dear Dr. Brew,


There are times, though few, but especially during the summer months, when our BUNN VP-17 is not used for several days. Because of evaporation, I suggest pouring in a pot of water, and discarding the smaller amount of water that fills the carafe. Otherwise, you end up with a small pot of very, very strong coffee! Because we have a crew of environmentalists and engineers, there is the contingent that thinks one only needs to add a small amount of water until it begins to drip into the pot, wait for the drip to stop, and then add the entire pot of water. Since I have no diagram of the pot, I bet you know the absolute right way to do this!!

Second question -- the instructions indicate regular deliming of the BUNN, but offer no formula for doing so. We have the magic spring and know how to use it. What else should we do? We have owned this pot since 2003, and I KNOW it has never been delimed, because no one else would even think of it. We had a double BUNN that developed a leak before these pots, and it is probable that the leak developed because IT was never delimed either. Such is life in a church family with a couple hundred members.


Many thanks.


Ruth
Davenport, Iowa



Answer


Here's the answer to your first question -- I'll answer the second in a later post.

Dear Ruth,

The loss of water from the internal tank is due to evaporative loss during infrequent use. Either of your approaches will work. I prefer yours -- and the excess water from the refilling of the tank can be used to water plants, satisfying the environmentalist in all of us. This type of commercial brewer maintains the water at brew temperature inside the tank (similar to a water heater, but the water is not under pressure).

Happy Brewing,
Dr. Brew