 So, Dr. Seena Fisher, welcome to the soba. Thank you for having me. Come and tell me about your research that you're exhibiting here. Yes, so we studied the chocolate making process and in particular one aspect of that and that's the fermentation. So, I brought you here a cacao pod, this is sort of the outside, they come in a lot of different shapes and sizes and colors, some are red, some are green. And we cut one open here for you to see the inside, so these are the cacao beans and they are surrounded by this pulp. You can see a little bit better here, it's sort of moist and white initially and it contains a lot of sugar and if you smell the inside of these beans, the inside of this pod, what can you smell? It smells quite fresh, quite nutty, fruity, citrusy maybe, but certainly doesn't smell like cacao. No, no chocolate whatsoever. No chocolate whatsoever. In comparison, if you smell these beans, so these feel much more dry than what we just had there. It's almost like quite a stringent, quite sort of sour, almost like coffee. Yeah, so this is certainly much more nutty and much more going into the direction of chocolate already, so we're getting close here. Now the difference between this fresh bean, these fresh beans coming from the pod and these drier beans is that these were fermented, fermentation is of course microbes acting on food or other products, in this case the cacao beans and changing them in a way. And yeah, this has been a process that has been utilized by farmers for ages to make chocolate in the end. Without the fermentation, you could roast these beans all you liked, you would never be able to turn them into chocolate. They would remain very bitter, these citrusy flavours would remain predominant and you would not get the chocolatey taste. So in the production making process of chocolate making, that fermentation process is crucial to the flavours that we love in chocolate. Absolutely, yes. So where does the science come in then? We study this process. We investigate which microbes are present during the fermentation and how they change. The fermentation is usually done, not usually it's done at the farms, so the cacao is harvested by farmers and these beans and the mucusy like pulp are scooped into big wooden boxes and then the beans are left there to ferment for about five days. And after that time they would have this colour and they would be placed outside to dry and then they're ready to shipment to the chocolatier and then they would proceed with further refinement steps. And a good chocolatier is able to really tease out all these great notes in the chocolate, but if they get low quality beans there's nothing they can do about it. So the fermentation is really crucial in this process and what we want to know, if we have chocolate that tastes fruity, has berry notes and we have a chocolate in comparison that has more floral notes or almost tastes like vanilla, then what was the difference during the fermentation? So sort of reverse engineering almost, working out what happens during that process, what microbes were acting to create that fermentation. And then I guess if you want to in the future purposefully create certain flavours in a chocolate you would be able, you would know what bacteria or what microbes are required. Exactly, yeah it's much more complicated than let's say for example wine making because as you know wine is also fermented but here we need yeast and it's mainly yeast. There are a lot of different yeast strains known to brewers and they would even cultivate them and add them to their certain wines. Although yeast is already growing on the grapes themselves so it's not technically required but they can refine it this process. But for the fermentation of cacao we've noticed that if you just add yeast for example you would not be able to produce these cacao notes and if you just add bacterias of certain kind you would also not get these different flavours. What you really need to have is a specific combination and of course if I start to combine only three things it goes up but we have we have studied this in several thousand samples now and we see hundreds and difference of microbes during the fermentation. Their profiles change from day one to day five. In concert with that the pH changes, the temperature changes on all of these are important factors so it's just it's a much more complicated process. A very complex process and so are those the microbes that are responsible for the fermentation are those present they must be present presumably sort of in the bean or in the place in which the beans are coming from so do you see bacterial variation in terms of where the beans have grown and is that the sort of root of the different flavours. It's an excellent question yes so we asked this as well because it wasn't known right so this process was completely not studied scientifically. Farmers have a certain ability to control fermentation by stirring changing temperature and so on and so forth but what we did was we went to Columbia and to Trinidad and we work with farmers there they are usually small farms family run and we were asking them well would we be allowed to participate in your harvest and take samples so we went we took samples from the surface of the pod from the inside of the pod from the boxes that the fermentation is occurring in and then throughout in order to answer these questions and basically the answer is they're everywhere and they are very diverse between different farms so not even say Columbia has a different microbiome to Trinidad but a specific farm in Columbia has a very specific microbiome and this is why if you want to have really impressively unique experience in tasting chocolate you need to buy a single origin chocolate because there you get these unique flavour developments and these fine flavour chocolates also have the characteristic that they don't taste the same throughout so you start tasting a piece of chocolate and it would start out maybe a little bit bitter a little bit sour but then this would fade away and you would get all kinds of other notes coming through and this is characteristic for all fine flavour chocolate as soon as you start to bulk which is what you get in bulk produced chocolate you lose that characteristic so yeah it's sort of blend if in a blend you wouldn't get those specific flavours super interesting and how does your research impact the people that are responsible for growing the beans you know farmers that are working on this does your research help them in any way this is our goal yes so we work with as I mentioned these small farmers actually the majority of cacao especially in South America is grown on small farms so for them if the fermentation doesn't go quite well and produces what we call off flavours which could be a very bitter notes or sometimes almost moldy tastes then they the quality of the bean would be much lower than they would like and they'd have to sell it at a less price than they need to basically sustain their businesses so our hope is by correlating flavours and microbes we would be able to advise them on best practices how do they avoid these bad fermentation outcomes sure dr. Cina Fisher from the University of Nottingham thank you for explaining the science of chocolate to me and I wish you all the best with your research thank you very much thank you