Category Archives: Food Science and Technology

Cheese and disease: how bacteria survive long term

This week we have Andrea Domen, a MS student in Food Science and Technology co-advised by Dr. Joy Waite-Cusic and Dr. Jovana Kovacevic, joining us to discuss her research investigating some mischievous pathogenic microbes. Much like an unwelcome dinner guest, food-bourne pathogens can stick around for far longer than you think. Andrea seeks to uncover the mechanisms that allow for Listeria monocytogenes, a ubiquitous pathogen found in dirt that loves cheese (who doesn’t?), to persist in dairy processing facilities.

Listeria hysteria

Way back in the early 2000s, there were two listeriosis outbreaks that were linked to cheese. Because of these two outbreaks, the British Columbia Centre for Disease Control conducted a sampling program over the course of a decade. From this program, 88 isolates of L. monocytogenes from five different facilities were recovered. Within this set of isolates, 63 were from one facility which is now (perhaps unsurprisingly) shut down. Those 63 microbes were essentially clones of each other, which means this one lineage of microbes seemed to carry something that allowed them to survive for multiple years. So how did that lineage of Listeria survive? Turns out, like a 1990’s Reebok, they pump it. Listeria uses a protein in its cell membrane called an efflux pump to remove harmful chemicals like sanitizers, antibiotics, and heavy metals from the cell. Essentially, when the cell absorbs something that is too spicy – it’ll yeet it back out. 

gif of an efflux pump

Don’t cry over contaminated milk

The idea that food borne pathogens are evolving to withstand processing environments is alarming, but fret not, the results of Andrea’s research are a first step to avoiding the creation of these super microbes in the first place. Instead, it can serve as a warning story for dairy production facilities about what can happen when L. monocytogenes contamination isn’t properly handled. In healthcare, it’s not uncommon to treat a microbial pathogen with multiple medications – as becoming resistant to several treatments is harder for the microbe than becoming resistant to just one. We are also able to apply this treatment method to sanitizing food production facilities by combining different sanitizers – but that is best left up to the chemists to avoid accidentally making an explosion or lethal gas. 

Andrea Domen

To hear more about how Listeria can survive better than Destiny’s Child be sure to listen live on Sunday, May 7th at 7PM on 88.7FM, or download the podcast.

Nobody wants to eat bitter cheese

There are many adjectives used to describe the taste of different kinds of cheese: mild, tangy, buttery, nutty, sharp, smoky, I could continue but I won’t. Our preferences between these different characteristics will then drive what cheese we look for in stores and buy. But I would wager that most people (or dare I say anyone?) are rarely looking for a bitter cheese. I had never thought about how cheese could be bitter; probably because it’s something that I’ve never tasted before and that’s because the cheese production industry actively works to prevent cheese from being bitter. Intrigued? Good, because our guest this week researches why and how cheese can become bitter.

Paige in the lab

Paige Benson is a first year Master’s student advised by Dr. David Dallas in the Food Science Department. For her research, Paige is trying to understand how starter cultures affect the bitterness in aged gouda and cheddar cheeses. The cheese-making process begins with ripening milk, during which milk sugar is converted to lactic acid. To ensure that this process isn’t random, cheese makers use starter cultures of bacteria to control the ripening process. The bitterness problems don’t appear until the very end when a cheese is in its aging stage, which can take anywhere from 0-90 days. During this aging process, casein proteins (one of the main proteins in milk and therefore cheese) are being broken down into smaller peptides and it’s during this step that bitterness can arise. Even though this bitter cheese problem has been widely reported for decades (probably centuries), there are many different hypotheses about what causes the bitterness. Some say it might be the concentration of peptides, while others believe it’s a result of the starter culture used, and a third school of thought is that it’s the specific types of peptides. Paige is trying to bring some clarity to this problem by focusing on the bitterness that might be coming from the peptides.

To accomplish this work, Paige will be making lots of mini cheeses from different starter cultures, then aging them and extracting the peptides from the cheese to investigate the peptide profiles through genome sequencing. Scaling down the size of the cheeses will allow Paige to investigate starter cultures in isolation as well as in combination with different strains to see how this may affect peptide profiles, and therefore potentially bitterness.

Some of the mini cheeses Paige makes for her research

Besides Paige’s research in cheese, we will also be discussing her background which also features lots of dairy! As a Minnesotan, Paige grew up surrounded by the best of the best dairy. In fact, her grandparents owned and ran a dairy farm, where Paige spent many of her summers and holidays. Her passion for food science was solidified when she started working as an organic farmer during her senior year of high school and she hasn’t ever looked back. Join us on Sunday, April 16th at 7 pm live on 88.7 FM or on the live stream. Missed the live show? You can listen to the recorded episode on your preferred podcast platform!

What to do with all the whey?

You probably already know that skim milk and buttermilk are byproducts of cheese-making. But did you know that whey is another major byproduct of the cheese-making process? Maybe you did. Well, did you know that for each 1 kg of cheese obtained, there are about 9 kg of whey produced as a byproduct?! What in the world is done with all of that whey? And what even is whey? In this week’s episode, Food Science Master’s student Alyssa Thibodeau tells us all about it!

Alyssa making cheese!

Whey is the liquid that remains after milk has been curdled and strained to produce cheese (both soft and hard cheeses) and yoghurt. Whey is mainly water but it also has lots of proteins and fats, as well as some vitamins, minerals, and a little bit of lactose. There are two types of whey: acid-whey (byproduct of yoghurt and soft cheese production) and sweet-whey (byproduct of hard cheese production). Most people are probably familiar with whey protein, which is isolated from whey. The whey protein isolates are only a small component of the liquid though and unfortunately the process of isolating the proteins is very energy inefficient. So, it is not the most efficient or effective way of using the huge quantities of whey produced. This is where Alyssa comes in. Alyssa’s research at OSU is focused on trying to develop a whey-beverage. Because of the small amounts of lactose that are in whey, yeast can be used to ferment the lactose, creating ethanol. This ethanol can then be converted by bacteria to acetic acid. Does this process sound a little familiar? It is! A similar process is involved when making kombucha and the end-product in Alyssa’s mind isn’t too far off of kombucha. She envisions creating an organic, acid-based or vinegar-type beverage from whey. 

Morphology of yeast species Brettanomyces anomalus which Alyssa is planning on using for her whey-beverage.

How does one get into creating the potentially next-level kombucha? Alyssa’s route to graduate school has been backwards, one that most students don’t get to experience. While the majority of students get a degree, get a job and then start a family, Alyssa started a family, got a job, and then went to graduate school. On top of being a single mother in graduate school, she is also a first-gen student and Hispanic. To quote Alyssa: “It makes me proud every day that I am able to go back to school as a single mom. In the past, this would have maybe been too hard to do or wouldn’t have been possible for older generations but our generations are progressing and people are making decisions for themselves.”.

Intrigued by Alyssa’s research and personal journey? You can hear all about it on Sunday, January 29th at 7 pm on https://kbvrfm.orangemedianetwork.com/. Missed the live show? You can listen to the recorded episode on your preferred podcast platform!

“Creepy” Beer

Happy Halloween from the ID team! This week we’re chatting about a popular halloweekend beverage: Beer and a “creepy” phenomenon seen in a west coast favorite, IPAs. Hop creep may not mean that there are creepy crawlies in your beer, but it may lead to exploding cans or a beer that’s all trick and no treat. To find out more, we are talking  with Cade Jobe on his work on hops maturity and its impact on understanding this spooky problem facing the beer industry.

Cade Jobe, a 1st year masters student in FST

Cade is a 1st year masters student in the Department of Food Science and Technology at OSU, where he works under the advisement of Dr. Tom Shellhammer. In the “Beer”, or “Hops”, lab there are a wide variety of projects on the various components of beer, in addition to offering resources to the brewing industry by running standard analytical measurements on hops. Cade moved to Oregon in pursuit of joining the Hop Lab, after falling in love with home-brewing and embarking upon a career shift from law to food science. While his master’s work is going to be more focused on the impact of wildfire-smoke on hops, his post-baccalaureate work focused on hop maturity, in particular the Citra hop variety.

How does one study the impact of hop maturity? Cade worked with a hop grower in Yakima, Washington to harvest hops from 3 fields at 7 different time points during the hop picking season. These dried samples were then sent back to Corvallis where they underwent standard hop chemical analysis, sensory analysis, and enzymatic analysis.

Cade and team harvesting hops
Cade pelletizing hops

This is all great, but how does it help me drink beer? From the chemical analysis, there are standard components that are measured to give an overall hop quality measure to know if it is going to produce the desired result. From sensory analysis, they can see what aromas are associated with the different maturity levels of the hops and what aromas they would impart in beer. Spoiler: late season hops might identify if you are a vampire! And finally, going back to the exploding beer cans, the enzymatic analysis shows the potential of hop creep occurring so that brewers can mitigate the problem.

Want to learn more about the science behind beer and more on Cade’s research into hops? Tune in Sunday, October 30th, 2022 at 7 PM on KBVR 88.7FM (https://kbvrfm.orangemedianetwork.com) or wherever you get your podcasts! 

Also, if you’re interested in learning more about the wide-world of brewing, check out Cade on the “BruLab” podcast.

This blog post was written by Jenna Fryer and posted by Lisa Hildebrand.