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Balancing act – Sweetness

12/07/2009

Like I mentioned in my post “How sweet is your cup ” I find the balancing of fruit sweet (fructose) with the sugar browning reactions or caramelization to be somewhat of a conundrum. The idea that sucrose in its most pure form is actually sweeter then it’s caramelized counter part fascinates me. For the purpose of this post I will focus solely on the above and will talk about other reactions and their perceptions in the cup later.

The goal for us is to actually achieve maximum sweetness, so knowing (or at least approximating) what sweetness is being developed at what time and temperature during the roast cycle, is key.

I can assume that we all know that there are an infinite amount of variables to contend with, so let me talk about some of our findings that I have witnessed to be consistent here in LA.

It is time to talk about our “ideal” roast profile (for me) and delve more into to the balancing act.

First of all we need to know what we are trying to achieve with the coffee that we are roasting, this starts at the cupping table as we are evaluating coffees for purchase. Knowing what brew method this coffee will ultimately be used for (to some degree) , plus determining what the coffees large flavor descriptors are, is vital.

Please note that temp and time’s that are given are directly read of our equipment, so temps may differ depending on accuracy of temperature gauges. It is also important to note that these are my thoughts and may not reflect Intelligentsia’s opinion.

Following Carl Staubs theories of sucrose development I prolong the “golden period” where the color of the once-green coffee bean changes from pale yellow to bright orange. We allow the roaster to gently heat the beans and maintain a low minute-to-minute temperature increase. It is in this stage of the roast between minutes 2 and 7 – 8  and at 230-340°F that the Polysaccharides split of into Monosaccharides building a foundation of simple sugars for us to work with latter on.

Between 7 and 12 minutes and 240-392°F, we are starting to dig into the foundation of sweetness that we had just built, and the beans start the Maillard reaction, which is the caramelization of those simple sugars.

At the beginning of this period we start to apply more heat so we can stay ahead of the exothermic reactions. If the environmental temperature stays ahead of the bean temperature, we are less likely to lose the simple sugars that have developed as paralysis of the cellular structure breaks down and first crack occurs. I will explain more about exothermic reactions in another post.

If I have come into first crack with enough heat and momentum I will typically turn the gas to it’s lowest setting and just ride  out the rest of the roast. The amount of time that it takes between first crack (I measure from it’s most volitile/ noisy) till the point that I drop out will also greatly impact flavors into the cup. I feel it is between these two points that its when we will enevitable start to introduce carbon into the beans make up.

There is a tipping point, at which time we start to introduce “phenol” or medicinal-taste qualities into the coffee and you actually start loose those sweet caramel flavors. We start to dig even further into those sweet notes and we have an introduced human element to the bean…and all you can taste is the degree of roast. Rather than tasting the intrinsic qualities of the coffee, we taste something more akin to burnt rubber, smoke and charcoal…flavors that could be derived from burning into any organic materials that’s left in the coffee.

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4 comments

  1. Thanks for the interesting post Deaton! I’ve been brushing up on organic chemistry lately in the hopes of demystifying the science of roasting.

    Fructose is quite interesting to look at, given that it begins caramelization very early in the profile (caramelizes at 230F) but then reappears around your 8 minute point with the caramelization of sucrose (yielding glucose and fructose), thus lending to both further maillard development and further caramelization towards the end of the roast.

    I wonder if maximum sweetness is somehow a function of allowing sufficient energy and time to caramelize sucrose, thus yielding fructose and glucose, while not allowing so much time afterwards to ensure these resulting sugars do not excessively caramelize or react with remaining amino acids in maillards.

    Or here’s another thought: is maximum sweetness obtained by reducing the concentration of amino acids as much as possible prior to the caramelization of sucrose, such that the resulting “new fructose” has no amino acids to react with and can therefor only caramelize? To make things even more interesting, wouldn’t the reduction in oxidizing reactants (namely Oxygen) allow this caramelization to be minimized as well, thus further increasing potential fructose concentrations? Now there’s an interesting argument for the Loring!

    I should note that I’m not a roaster and barely know what I’m talking about here… but these thoughts are a lot of fun to explore nonetheless!


    • Just to take back the comment on oxygen and carmelization reactions… after a little further reading it seems carmelization doesn’t actually involve such reactants. Never mind!


  2. […] “Balancing Act Of Sweetness – My Most Viewed Post, Updated” […]


  3. […] Please see linked post if you want to know what I am talking about. […]



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