Mapping flavour (and more) inside your food

The team sliced the mushrooms into thin sections before analysing them with the MSI machine. It was surprising to see that some molecules were more present in the cap and some more in the stem, a kind of heterogeneity most people already sense intuitively in the kitchen. "We obviously also experience this during cooking," Mudita says. "For example, when I add coriander to a sauce, I remove the stems because they're more bitter than the leaves."

That same principle, that where a molecule sits changes how food looks, tastes and feels, turned out to matter well beyond mushrooms. Mudita has since applied MSI to plant-based meat alternatives, working with a company developing plant-based burgers. "You really need to come close to what people love as texture, flavour, and how it looks like," she explains. "Sometimes you make a beautiful looking alternative burger, but as soon as the consumer eats it, it does not taste like meat." One striking finding: when a meat burger and a plant-based burger are grilled side by side on the same surface, fat from the meat spreads across the grill and is picked up by the plant-based burger, and people rated that plant-based burger as tastier than one cooked on a separate grill. Even foods that look completely uniform, like tofu, turned out to have their own hidden flavour structure once imaged.

Flavour isn't the only thing MSI can image, it can also reveal how food degrades. For the food industry, understanding how far off flavours penetrate a product, and which parts are most likely to spoil first, can be just as valuable as understanding what makes food taste good. The same goes for contaminants like pesticides: knowing how deep they've penetrated can determine whether peeling the fruit is enough to remove them or whether the risk runs deeper.
Mudita's most recent work looks specifically at drugs and microplastics entering the food chain through sea animals such as mussels. Because mussels are filter feeders, contaminants present in the water around them show up clearly in MSI images. 

The research is done in collaboration with PhD candidate Luan Valdemiro Alves de Oliveira at CIMAR in Porto, Portugal. There, he exposes mussels to microplastics and pharmaceuticals at concentrations ranging from natural to high. At natural, environmentally realistic concentrations, a single mussel does not necessarily contain a harmful dose. However, that changes when accounting for realistic food consumption, since people rarely eat just one mussel at a time. The team is also investigating whether specific washing steps can reduce contaminant concentrations before mussels are eaten.

"I never thought I would be dissecting seafood to look for microplastics," Mudita says. She is a vegetarian herself, and the contaminants research is a newer, still-developing direction compared to her flavour work.