I don’t have a great answer for this. Well, I have answers, but they are not definitive. Overall, I have an unsubstantiated preference for beans and roasts that pop and crack, but pretty clearly it is not a necessity for a good roast, nor is it an indicator of a good roast….but it does fall into the more favorable category for me.
What in the world does that all mean? Let’s face it. Listen for pops and stopping your roast there is easy. If you follow most any of my roasting suggestions you will get a few beans to pop most of the time, and the results will be good. And I’ve personally found with my roasting style, if beans are popping I am satisfied by the roast. That said, JUST making the beans pop isn’t the goal. You can really sear and char the beans by applying too much heat and they will pop just great. But they may mot taste very good.
Taking a small step back, popping is something you are probably familiar with. Most seeds pop if you heat them. Popcorn. Classic example and the most dramatic. Heat up the kernel and the water inside super heats and pressure increases. When that pressure can no longer be contained, the kernel ruptures, water vapor is explosively released and you hear a pop. It’s basically the same thing with sunflower seeds, sesame seeds, coffee (it actually pops twice, 1st and 2nd crack) ……and cocoa.
That said, you can see there are three factors (at least) for getting cocoa to pop. Heat, moisture and intact cell structure. If you heat the beans very slow the moisture will have time to make its way out without cracking or popping. If the beans are very dry there isn’t anything there to make them want to pop and if the beans are broken or cracked already, no pressure can build up. Remove any one of those and the beans won’t pop.
In the first case, there are many people out there that like very long (over 30 minutes) and/or cool (under 225 F) roasts. Beans won’t generally pop under those conditions. I’ve found it takes getting the bean temperature to around 250-260 F before it will occur. Can these be good roasts and make good chocolate? Yeah, it’s possible. But I’ve found it is not generally to my taste, so I try to avoid those kinds of roasts.
In the next two cases, you are more dealing with possible quality issues. Good beans that have been fermented and dried well should have an intact cell structure and a moisture content of around 7-8 %. Outside those parameters and it’s easier to have beans that don’t taste as good. Cracked beans can give paths of ingress for bacteria. Not good. The can indicate rough handling. Not good. Low moisture can make beans for friable (brittle) and prone to cracking. And why are they low in moisture? Were they artificially dried at too high of a temperature thus changing the flavor?
And taking the other side, have a look at these Honduras beans that just came in (and are gone) that I roasted. Just an amazing amounts of pops. 10-15%. Maybe even 20%. And they tasted great.
But correlation is NOT causation. Just because they popped did not make them good. More likely the moisture was a tad high because they were very fresh having been flown in from origin just last week. It helped too that I roasted them very strongly and they were pristine beans. Basically a perfect storm for snap, crackle pop! But I've had some Brazil that did the same thing that I did not offer because it tasted like soggy cardboard - aggressive cracks and all.
If you notice I am using lots of qualifiers. It is so difficult to make absolute statements of fact about these things as I’ve found so many exceptions. I’ve had very dry beans that popped just fine. I’ve had beans that showed poorly because they were cracked and very dry and didn’t pop, but the resulting chocolate was great. And I have had pristine, intact beans that popped like crazy that tasted like dirt. There is almost no predicting it….from this side of the tasting table. But really, this isn’t something you have to worry about.
You are not having to evaluate beans. That is my job. I’m pre-sorting for you and only offering beans that I’ve found taste good. Regardless of whether the popped when I roasted them. So from your point of view, at least with our beans, you don’t have to worry whether they pop or not. If they do, great. If they don’t, no harm, no foul. To be fair, most of the beans I offer do pop at 250-260 F when roasted in 12-18 minutes and can be considered done with they do. And I try to warn you when they don’t. Regardless, if they don’t pop for you, that is fine. You are not necessarily doing anything wrong and it’s not an indicator you have ruined the roast.
As a final side note, I have found I particularly like the taste of popped beans compared to their unpopped compatriots in the same roasting batch. But that is very specifically for eating whole. Given that even on a good batch, you may only see 5% popped, I’ve yet to ever sort out popped specifically to see if they make exceptional chocolate compared against the rest of the batch. Maybe I’ll try it some day, but mostly it would be purely an academic exercise as it just isn’t a practical way to make chocolate.
So, to bring It home, you really answered your own question when you said the chocolate with only a couple pops was fine. That is par for the course. A few pops and the chocolate tastes fine and those two things are only barely related. Remember, correlation is NOT causation. It’s just an observation. Happy chocolate making everyone.