Non-alcohol beers have been around since the early 1900s. But it wasn’t until the 1920s and the implementation of Prohibition Laws in the U.S. that they became “popular”. Despite their legal status and availability, they were never considered to be very good. This was because the ethanol was removed using …
Global warming and Prof’s nightmare
Although we will not devote much time to this topic, climate change and global warming are already having serious effect on many fermented foods. Among the products perhaps most sensitive to a change of just a degree or two are wine grapes. Interestingly, there will be winners and losers. The …
Fermented foods, a global perspective
It’s fun to consider how our eating habits have changed over time. When I was in college, I was aware of only a few fermented foods – cheese, sour cream, pickles, bread, beer, and wine. I had never heard of kimchi, kefir, or miso, and perhaps no one in America …
Fermented foods: 150 years of cutting edge science
I have been studying fermented foods for more than 40 years. Although I had a lot of company during that time, as a branch of microbiology, it was a rather small group. We usually published in applied microbiology journals and obtained grants from industry or commodity groups like the dairy …
Really smart packaging
You are at the grocery store to purchase a package of fresh ground beef, or a bag of green beans, or some fresh salmon. Maybe you can gauge freshness by appearance or you perhaps you rely on the sell-by date. But you cannot smell or touch. So how do you …
Stressed out
Quercetin is a natural polyphenolic compound found in plants. It has several beneficial health benefits, due, in part, to its antioxidant and anti-inflammatory activities. It may also have antimicrobial properties. In this 2020 paper published in Food Microbiology, the authors showed that quercetin damaged bacterial membranes (making them more permeable) …
Extending yogurt shelf-life, naturally
I noted in class that yogurt has a long shelf-life, usually many weeks longer than indicated on the labels “use-by” dates. After all, yogurt is made from milk that has received a high-temperature heat process. Most yogurts are made in a hygienic environment with minimal exposure. Importantly, the final product …
Cookies safe to eat
Most food preservation articles that get published in food microbiology journals refer to industrial processes. On occasion, I’ll come across a paper that addresses a very applied sort of problem. Such is this paper from the December 2021 issue of Food Microbiology. As we noted in class, Salmonella can sometime …
Low Moisture Foods – not always cut and dry.
Low moisture foods (LMF), as mentioned in class, have water activities too low to support growth of bacteria of public health concern. Indeed, according to the European ILSI, CODEX, and other authorities, the cutoff water activity for these foods is 0.85, below which pathogens cannot grow. These include a wide …
Psychrotrophic bacteria in foods, an old problem that never went away.
In class, I described a paper from the 1960s that discussed how low temperature storage of milk has selected for psychrotrophic spoilage bacteria. I also showed data on the increased expression of proteolytic enzymes by these bacteria when grown at low temperature. Flash forward 60 years, and food microbiologists are …
Food preservation not always so easy
One of the best examples of modified atmosphere packaged foods are the fresh salad greens and spinach products one finds in the produce section of the grocery. The reduced oxygen levels in these products, whether in bags or clam-shell packages, inhibits growth of Pseudomonas and other aerobic psychrotrophs. As we …
Some like it cold
When we consider food preservation and shelf-life of foods in the home, one of the most important determinants is often the most over-looked. It’s your home refrigerator. After all, that’s where we keep our milk, meat, poultry, eggs, and most of our fruits and vegetables. If the refrigerator is not …
Explaining foodborne pathogens through song and animation
Occasionally, it is nice to find creative scientists who have explained complex science in entertaining or more dynamic formats. (As with everything found on the internet, it’s important to check accuracy against known sources). Here are a few good examples I have found describing specific foodborne pathogens over the years. …
Norovirus on the Pacific Coast Trail
For several of the pathogens we will discuss (such as Shigella, Staphylococcus aureus, and Norovirus), transmission from other humans through poor sanitary practices is an important risk factor. Surface transmission seems to be the major factor behind an outbreak of Norovirus that occurred among hikers on the Pacific Crest Trail. …
Trichinella outbreaks
In class, I mentioned that Trichinella had been largely eradicated from swine herds and was not as much of a concern for food microbiologists. However, outbreaks caused by Trichinella still happen. These outbreaks are usually linked to consumption of wild game, such as an outbreak in Spain linked to consumption …
Nanotechnology to detect and eliminate foodborne pathogens
This week in class we will be talking about traditional and rapid methods to detect microbes in food. While some of the techniques we will discuss are relatively new and innovative, new technology continues to emerge as scientific advances in other fields are made. One interesting approach is the use …
Climate change and foodborne pathogens
As we briefly discussed in the first lecture, global climate change is likely to change our understanding of the dynamics of foodborne infections. A recent study from Germany focused on how climate change was likely to affect transmission of Campylobacter, non-typhoidal Salmonella, and Vibrio in that country. In Germany, rates …
Listeria in ice cream (again)
Each year I update this post with a new description of an outbreak of Listeria monocytogenes in ice cream. This year, it’s L. monocytogenes in milk shake machines that has killed 3 people as of this writing, and L. monocytogenes in soft serve to go ice cream cups that I …
A week of foodborne outbreaks
Despite how much food microbiologists know about keeping foods safe, food poisoning outbreaks still occur. How often, would you say, do outbreaks occur? Maybe once a week, once a month, maybe even once every 2-3 months? One good source for this information is the Food Safety News website (interestingly, it’s …