Every time we make chocolate at home, we try a new experiment. Richard is a scientist, after all; this is in his DNA! Sometimes, we test different cocoa beans, like we did here. Other times, we test percentages of sugar. This time, we tried different varieties of sugar. And wow, we learned a lot!
With the same exact cocoa beans, percentages, roasting times and temperatures, and process, we created three batches. The only difference among the batches was the type of sugar. Our first batch, we’ll name it A, used regular bleached cane sugar. The second batch, let’s call it B, included raw sugar or turbinado. And the third batch, you guessed it – C, had Truvia, made from stevia.
We also tried a new method of cooling. Rather than plopping the finished chocolate onto the granite slab and separating it into bite sized pieces with our paint scraper, we created “kisses.” We filled Ziploc bags with the chocolate liquor after it was roasted, winnowed, ground, and tempered and squeezed it out onto the slab. We ended up with about 50 tiny kisses per batch (yes, we’re working with infinitesimal quantities at the moment).
The first major lesson we learned from this process was that stevia is really sweet. That seems obvious, since it’s sugar. However, if you taste it right before or right after cane sugar, the difference between the two is palpable. The difference between turbinado and cane sugar is less stark but still noticeable. And this is all before we put it in chocolate.
Next, during the grinding process, we learned that turbinado results in a drier mixture. So, even though we still refrained from adding any cocoa butter to the list of ingredients, the result was thicker and a little grainier than the other two samples.
With our new cooling method, we learned that the crystalization process happens more thoroughly when in direct contact with the granite slab. In other words, our kisses were well crystalized, harder, smoother, and more likely to have that traditional chocolate crack when we tried to break them apart, but only in the first centimeter or so from the granite. The parts of the kiss that didn’t touch the granite had the same partial crystalization that our previous chocolates had. We’re still working on optimizing this process to create the best possible texture and shelf life.
The fourth lesson takes us into scientific territory. Batch C with stevia provided a particularly strange tasting experience. Typically, if you were to put chocolate on your tongue, it would begin to melt as it warmed to the temperature of your mouth. However, the chocolate with stevia seems to cool as it melts. In other words, it melts colder than room temperature, rather than the other way around. Richard and my brother (a PhD student at Stanford) dug into the deeper meaning behind such a surprising phenomenon. They’ll have to follow up with their conclusions, because I don’t share in their scientific understanding. Another subject for another day!
Our final lesson was the most fun – taste testing the kisses and sharing them with friends and family. According to our many official tasters, the batch A with cane sugar was the clear winner. Batch B with turbinado came in a close second. And Batch C with stevia had only one fan of the many who tried the three batches. In fact, most people tasted one kiss and wanted nothing to do with it afterwards.
And as a bonus, we learned the opinion of a repeat taster, one who tasted our very first batch of chocolate from the beans we bought at the Grand Central Market in Los Angeles. She let us know that these three batches of chocolate’s texture, taste, and overall experience are leagues ahead of the first batch we ever made. Thank you, Helen, for being our first brand ambassador!
Update (August 14, 2014): For those of you curious about why stevia melts cold, Matt (my PhD of a brother) has figured it out:
So I found out why the chocolate with the Truvia causes a cooling effect in your mouth as you eat it. So, the sweetening agent in Truvia is stevia, but Truvia has other ingredients, like erythritol (erythritol is basically glycerol but with one extra carbon atom and hydroxyl group). Erythritol has a negative heat of solution, meaning that it takes more energy to dissolve the stuff than is released upon dissolution. So, as the erythritol dissolves, it takes up heat from its surroundings and the temperature decreases. So, if you drink something with erythritol in it, you do not get this effect since it is already in solution.
Cool, right? Mystery solved!