Please post links to any scientific studies about caffeine and theobromine in cacao.
I glanced through the second paper and found it somewhat unsatisfactory.
HPLC is a good technique, but it is not absolute. The authors appear to measure relative amounts of caffeine and theobromine versus external standards run on the same columns and match the elution times to assign peaks. In a real referereed scientific journal that solo method of assignment when others are available would not fly.
At the very least, for simple, low molecular weight compounds like caffeine, the authors should have done mass spec to conclusively nail down the molecule by its fragmentation pattern. Other absolute structure confirmation methods are readily available in better labs. Those include 1H NMR on aliquots collected in HPLC, 13C NMR and even 2D NMR.
Sorry, but imho this is inadequate science. Food industry ought to do what the big boy chemists do and meet the same standards for published research.
how does theobromine change from bean to bean? Because I assume there has to be some difference depending on the cacao variety and/or specific clone. Is there any info regarding this topic?
Based on the shoddiness of the cited paper (they never even bothered to absolutely identify or confirm via structural proof methods in analytical chemistry that what they eluted at time x was actually compound y), I would venture to say that the study of theobromine content of the bean vs region of production has not been done with any rigor. I suspect that the relative amounts do change with regions/strains/soils/etc. And because the relative amounts of these substances are present at fairly low concentrations and the variations likely rather subtle, it is that scientific rigor that would be most welcome here.
I think food science is learning the ways of organic chemistry, but it still has a long way to go. Analytical tools are expensive; research time is precious, and if there are no refereed publications of note or immediate financial benefits to be had, the motivation isn't there. The analytical toys we are required here (Mass Spec HPLC and 400+ MHz NMR, MALDI, etc.) cost hundreds of thousands and require highly skilled personnel working full time to maintain. Only a university or a large Fortune-500 type corp can afford that type of luxury.