Interview with Johanna Björkroth, professor, Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine

Packaged food is a man-made ecological niche for spoilage bacteria. The microbial community within it follows ecological succession, a phenomenon more familiar to most of us in the context of a forest: the process of change in the species structure of an ecological community over time. A slice of fresh meat is home to a million species of bacteria, approximately 10 000 individuals per gram. This microbial community begins to grow the minute the meat is packaged in protective gas. The carbon dioxide atmosphere inside the package blocks the growth of 90% of the species. When the food is spoiled, there are 100 million microbes per gram but only less than a thousand microbial species have grown. Because the food is stored at cool temperatures, the remaining species are cold-tolerant lactic acid bacteria, enterobacteria and a few others.

I meet Johanna Björkroth, award-winning professor of food hygiene, in her room on a summer day on Viikki campus. What is so exciting about spoiled vegetables and meat?

“If you eat meat or vegetables packaged under protective gas, you are consuming bacteria identified and described by my team. Our work has a huge impact on the everyday life of us all and on the food industry”, Björkroth begins. “The science is fascinating in itself but it is also extremely motivating to be able to do something about food waste and sustainable food production. Our work is strongly linked with sustainable development.”

“Packaged food is a man-made ecological niche. The ecology in it is fascinating.”

If microbes spoil the food, why don’t you just kill them before enclosing the food in a package?

“It’s impossible and not even sensible to eradicate all microbes from foods. That is why understanding how microbial communities work is essential. Ecologically, we want to control the community and those species that cause most of the spoilage changes. Our aim is to keep the total concentration of microbes under one million per gram”, Björkroth explains.

Very little is known about how different microbial species interact. DNA sequencing can reveal which species are present, but even within one species there are strains that spoil food and strains that do not. The reason behind this variability is genetic diversity and differences in gene expression – the regulation of the activity of genes so that they work only when necessary and not all the time. RNA is the best reporter of how the genes connected with food spoilage are functioning. This information can then be linked to sensory quality, that is, what we humans taste and smell.

“Today, we have rapid tests for the total number of microbes or for the presence of a particular species. What we do not have, however, is a test for predicting the accurate rate of spoilage. We can only estimate an average shelf-life for food products, 12 days, for instance. That’s what the store owner has to live with and a lot of perfectly good food goes to waste or reaches consumers almost spoiled”, says Björkroth.

“It would be great to develop sensors that would observe the microbe community in real time and use it to calculate an accurate safe consumption time. But we are very far from that target. It doesn’t help that each foodstuff is home to a different community of microbes.”

How did you get started in business collaboration? What’s in it for you?

”I did my PhD in collaboration with the food industry”, Björkroth says. “I found and tracked the contamination of spoilage microbes in production environments. The work went well and spawned more collaboration later on.”

The benefit for professor Björkroth’s group is the opportunity to conduct high-level sampling experiments. The companies give her access to their processing facilities. When one batch of product spoils quickly and another more slowly, Björkroth’s is the go-to team.

“The situation with champion mushrooms lately is a typical example and we cracked it. We found that even if the mushrooms were stored in brine and in a cold room, certain microbes were still able to grow and all did not perish in later heating. We were able to give advice on how to improve the preparation of the canned products. Simple but effective.”

Björkroth’s latest Tekes project recommended avoiding oxygen in certain packaging. In the presence of particular foodstuff, oxygen leads to compounds that we sense as rancid. “It really is exhilarating in a way to be able to solve practical problems on top of basic research. Problem-solving is always fascinating”, Björkroth smiles.

“Björkroth’s is the go-to team when companies need to solve problems of food spoilage.”

Does business collaboration help your research in practical ways?

Björkroth waves an imaginary fruit in the air and says: “Well, we can buy our sample from the grocery store. Even for a longitudinal study, we only need 60 packages. Our work is not like clinical research where you need huge numbers of patients and their data: what we need are ecological niches and we prefer to build them ourselves. We conduct controlled experiments with standardized products. “

However, if the group needs samples of the product in an earlier stage of production before they hit the stores, they need collaboration partners and access to slaughterhouses and the spaces used for packaging, slicing, and cutting. One of the plans of her team is to collect a fresh carcass from a slaughterhouse, package it in the lab, keep it out of the company’s own cold chain and then see how the resulting microbiome differs from those in the regular products. ”In order to get access to somebody else’s facilities, you have to have a good relationship and mutual interest and motivation”, Björkroth outlines the requirements.

Any challenges in working with industry?

”We haven’t really had problems to speak of. We’ve always had joint interests and none of our partners have wished to avoid good or bad news”, Björkroth explains. Many of the quality directors in food industry are alumni from the University of Helsinki and some professor Björkroth’s former students. “However, company leadership may be a different story. The company’s quality department has to fight for resources to use in food hygiene studies. It’s quite natural that in a big company there is competition among different units – quality is always an expense”. This means that any research collaboration must have immediate relevance for business.

Industry collaboration is based entirely on private funding in professor Björkroth’s group now. ”We do microbial ecology. If the case a company is offering is interesting to us scientifically, we go for it. But we need to able to use the results in our own work.” Björkroth always has a contract for each project. “We keep it simple and crystal clear. When you clarify exactly what you can do and what the knowledge you produce can be used for, there’s no conflict of expectation – that’s absolutely essential.”

Companies have not stood in the way of publishing results as long as they are anonymous. They do not want the articles to lead readers to their products. They do not even want to be mentioned in acknowledgements. Usually the most eager collaborators have the best quality monitoring and it would be unfair to think that they have the worst problems.

“It’s exhilarating to be able to solve problems on top of basic research.”

What advice would you give researchers that are considering business collaboration?

“Firstly, if you don’t really want to do a project, don’t do it. Nothing good comes out of it. If the pricing is off or if the question isn’t quite the kind you think you can answer, leave it. Be aware of your own strengths and what you can offer”, Björkroth recommends.

“Secondly, try to think about the question from the company’s point of view. Why would the company order research from you? There has to be a positive impact on their productivity.  I can get super-excited about a metabolic route in a spoilage bacteria community and tell all about it to a company quality director who knows me very well. Most likely she will say : “Great, Johanna, that’s wonderful. But what can you DO about it?”

And finally, trust. Trust is essential. ”The partner must be able to trust that you won’t publish a study saying that the products of Company A have more bacteria than those of Company B. You have to use time and effort in building trust. Networking in conferences is one good way. It’s also fun, our collaboration partners are really nice people and experts in this field”, Björkroth says.

Is there unutilised potential for business collaboration in the faculty?

Björkroth thinks a minute. “Perhaps the clinical research in the animal hospital could provide good opportunities for young researchers to grow and work with different businesses. I know that they already do a lot but perhaps there is still more potential there“. The Viikki Animal Hospital is the only research facility working with patient data in Finland. That is why Björkroth thinks that there is a lot of potential there for expanding.

“Our students are more and more interested in the applicability of our research. Especially our PhD students are really serious about having an impact in the world. Sustainability means a lot to them”, Björkroth points out.

What lies in your own future? What are you excited about now?

”There are so many exciting things going on. The base tray of packages could be replaced with cardboard, but biodegradable barriers have issues with gas retention and fish and meat packaging can only let through so much oxygen. And of course humidity is always a challenge for bio-based materials. Nevertheless, good material could come out of sugar cane, for instance. We are always also interested in the anti-microbial properties of plants, rosemary, chili peppers, lignin. We’ve done some work on it previously, too.”

In a few years, professor Björkroth’s own core research might also take the crucial steps towards the ultimate target – quantitative markers of RNA expression of spoilage bacteria. ”We need an industry partner to develop the test based on our research and to provide technological platforms for commercializing our products. However, we need a few years of basic research for proof-of-concept testing first”, Björkroth muses.