Microbes & Fermented Sausages

By: American Chemical Society

Microbes in “starter cultures” impart a distinctive tang and longer shelf life to food like sourdough bread, yogurt and kimchi through the process of fermentation. To get a better grasp of how microbes do this in fermented sausages, such as chorizo and pepperoni, researchers reporting in the Journal of Agricultural and Food Chemistry carefully show that these tiny organisms change the composition of fatty acids in these meats, contributing to many desirable traits.

Fatty acids and related compounds can influence the quality of fermented foods. For example, one species of bacteria in sourdough cultures produces a type of fatty acid that increases bread’s resistance to mold. Scientists, however, haven’t had a good handle on how specific cultures drive the formation of these and other similar compounds in meat, partially because some of the previous studies on meats have not included a bacteria-free control. To better understand the link between microbes and molecules, Nuanyi Liang and colleagues wanted to see how the production of fatty acids within sausages varied depending on the microbial culture used to ferment it.

To do so, they prepared the meat three ways. In one method, they included only the bacterium Latilactobacillus sakei; in another preparation, they used both L. sakei and Staphylococcus carnosus. Both of these samples were made in such a way as to prevent contamination from bacteria in the environment. They treated the third sample — the control — with an antibiotic solution to eliminate the microbes naturally living within the sausage. Over the course of 20 days, they checked the sausages and found a markedly different profile for microbe-free sausage compared to the sausage containing either of the two microbial cultures. For example, the researchers observed that linolenic acid, an unsaturated fatty acid, was accumulating in the microbe-free sausage but not in the cultured sausage. Differences emerged between the two sets of microbes as well, with the sausage containing the L. sakei culture alone, for example, producing higher levels of coriolic acid, which has antifungal activity and, at higher concentrations, also imparts bitter taste. A better understanding of the biochemistry by which microbes influence the quality of sausage and other fermented foods will aid the production of consistent, long-lasting and good-tasting products, the researchers say.

The authors acknowledge funding from the Natural Sciences and Engineering Research Council of Canada Discovery and CREATE programs, the University of Alberta’s Meat Education and Training Network, the Canada Research Chairs program and Mitacs.

By Neal Vitale

Universities across the globe are struggling not only with how to educate incoming and returning students but with safe reopening of their research labs. Much of their focus is on the same approaches broadly recommended by health officials – social distancing, mandatory face masks, daily health screening and contact tracing.

“It’s been a ton of work for everyone – intellectually to develop new policies, physically to rearrange and manage buildings and administratively to manage work calendars and class schedules across a large campus,” says Abigail Snyder, assistant professor of microbial food safety at Cornell University. “Besides the resources involved in getting these plans off the ground, these policies necessarily mean that we’re operating at reduced in-person capacity and that there are budgetary shortfalls.” 

Professor of Food Science at the University of Nebraska-Lincoln Bob Hutkins  reports similar disruption. 

“Just like everywhere, my lab shut down in late March. Only a few critical functions were maintained, but lab research was effectively halted,” Hutkins says. “Some of my graduate students, however, also perform computational research analyzing microbiome data, so those projects were less affected. Still, the two projects that were most lab-oriented happened to be focused on fermented foods. Our lab did reopen in late June, so we are now (after a 3-month delay) almost back to where we were pre-COVID.”

Maria Marco, professor in food science and technology at the University of California, Davis, (and member of the TFA Advisory Board) adds: “As the pandemic continues there is an increasing financial and emotional toll on graduate students and postdocs whose research is now significantly delayed. This toll also applies to new students. I have a new international graduate student who is supposed to start work on a food fermentation project this fall but may not receive a visa to come to the US. Although she can contribute remotely, this barrier would cause significant hardship and prolong the time needed to complete the degree.”

The situation obviously remains fluid, as noted by Barbara Ingham, professor of food science, University of Wisconsin-Madison. 

“Things are changing pretty much on a weekly basis here,” Ingham says. “We were to move to Phase 2 in July; that is on indefinite hold. Our campus teaching schedule changes on a weekly (and sometimes daily) basis, etc. It’s hard to be up-to-date at this time.”

Professor of Foods and Nutrition and Extension Food Safety Specialist Elizabeth Andress at the University of Georgia echoes these themes.

“[The work] I was doing on coming up with home-based or small entrepreneur kimchi and sauerkraut variations that I was willing to put the UGA Extension name on to publicly release was ground to a halt this past winter/spring,” Andress says. “And I haven’t been back on campus since mid-February because of a fall injury followed by the pandemic restrictions, let alone reduced budgets are now not going to allow employment of help or any significant research that was self-funded pre-COVID. …policies for finding ways to do non-essential research and have multiple people in a lab are still undergoing constant new messaging and planning at UGA.”  

A somewhat more positive picture emerges  from Canada. Michael Ganzle is professor and Canada research chair in microbiology and probiotics at the University of Alberta. 

“Fermented food products including (sourdough) bread are not on the list of products with reduced demand during the COVID-crisis. To the opposite, many started making sourdough bread during the lockdown in Alberta, and I have been contacted by many (including TV and radio stations) on how to manage with sourdough,” Ganzle adds. “Research at UAlberta was temporarily reduced due to lockdowns of some services on campus, and reduced capacity/increased safety rules, but [research] never really stopped. With one exception, extramurally funded projects or graduate thesis projects were somewhat delayed but timelines were not substantially disrupted. The picture is different for anyone using animals or humans in their research projects, or those doing field research – these ramp up only now after a three month interruption.”

He attributes the relatively modest impact of the COVID-19 pandemic on research activities to appropriate leadership at the department/university/provincial (state) level that appeared to strike an appropriate balance of safety measures to “flatten the curve” with ongoing research/economic activity.

Snyder at Cornell also underscores the efforts being aimed at facilitating both the advancement of teaching and research missions as well as supporting robust protection of public health. “In truth, I wish we had policies like these generalized more broadly across the US.”

Adds Hutkins at University of Nebraska,”As inconvenient as the shutdown has been, the main issues for my colleagues and me have been to ensure that the lab remains a safe environment, that we practice social distancing and that students and staff stay physically and emotionally healthy.”

A new study links lower COVID-19 deaths to countries where the diet is rich in fermented vegetables. Researchers in Europe found in countries where the national consumption of fermented vegetables is high, the mortality risk for COVID-19 decreased by 35.4%. Results are currently preliminary and undergoing peer review. But, if the hypothesis is confirmed, “COVID-19 will be the first infectious disease epidemic to involve biological mechanisms that are associated with a loss of ‘nature,'” reads an article in News Medical. “Significant changes in the microbiome caused by modern life and less fermented food consumption may have increased the spread or severity of the disease, (researchers) say.”

The study was led by Dr. Jean Bousquet, a professor of pulmonary medicine at Montpellier University in France. After researching that diet may play a big role in determining how well people can fight the coronavirus, Bousquet says he now eats fermented foods multiple times a week.

Read more (News Medical Life Sciences

Is plant-based meat the next major trend for fermentation? Specialists at the Institute of Food Technologists’ (IFT) July virtual event said more product formulators are using fermentation to optimize food flavor and preservation. They predict using fermentation to create plant-based meat will be the next big trend. Culinary experts like Noma in Denmark are already discovering “uncoupling traditional culture-substrate combinations is a viable way of discovery in fermentation,” says Jerome Diaz, a doctor at Wageningen University and Research. He said: “Traditionally, fermentation as a means of improving food quality has been the basis for many of the foods we enjoy today. Examples of such food products include beer, wine, cheese, sausages, sauerkraut, among many others. Over the years, increased understanding of microorganisms and the unique functionalities they bring to food allowed the use of fermentation for the production of specialty ingredients.”

Read more (Food Ingredients First

The fermentation science programs at three Tennessee colleges — Middle Tennessee State University, Columbia State Community College and Motlow State Community College — secured a major grant from the U.S. Department of Agriculture. The schools aim to use that $300,000 grant to increase enrollment in fermentation science degrees. The three-year grant will also be used to introduce fermentation concepts into organic chemistry, microbiology and mathematics courses, aiming to drive fermentation science as a career option.

“Students in general aren’t aware of what fermentation science is, much less that it’s actually agricultural,” said Troy Johnston, professor and director of the MTSU Fermentation Science program. “The grant seeks to get more students interested in agriculture as a career.”

He adds: “Agriculture is an applied STEM (science, technology, engineering and math) field, but it is not traditionally viewed this way. The grant provides an opportunity to connect the dots between STEM courses and agriculture and raise awareness of and increase the potential for a student to become interested in the applied STEM career that is fermentation science.”

Read more (Murfreesboro Voice)

A food science professor weighs in on the Sqirl restaurant mold scandal. The trendy Los Angeles eatery is famous for serving toast on a housemade jam without preservatives. But allegations surfaced that Sqirl was making the jam in an unlicensed kitchen where buckets of jam were covered in mold. Dr. John Gibbons, an assistant professor of food science at University of Massachusetts Amherst, is an expert on beneficial and detrimental molds. He says: “Because I study this stuff, and I’ve seen some of the really bad effects of different toxins, I don’t really take chances with it. That being said, fungal-fermented foods are some of my favorite foods — I just don’t trust it happening spontaneously.”

Read more (Grub Street)

A new study shows kefir affects the microbiota-gut-brain axis. Researchers at APC Microbiome Ireland SFI Research Centre at University College Cork and Teagasc published their results in the journal Microbiome. They found that feeding mice kefir reduced stress-induced hormone signaling, reward-seeking and repetitive behavior. Interestingly, different types of kefir affected mice behavior and changed the abundance of gut bacteria. The researchers concluded that kefir should be studied as a dairy intervention to improve the mood and behavior in humans.

Read more (APC)

“You are what your bacteria eat.” – Donna Schwenk, author of “Cultured Food for Life”

INVIMA, Colombia’s National Food and Drug Surveillance Institute, released a “sanitary alert” against kombucha. The alert said: “It should be noted that ‘Scoby’ is an ingredient that has not been authorized by INVIMA for use in food and beverages.” INVIMA’s inspections found irregularities detected in locally-produced kombucha, and called out five Colombian and one U.S. kombucha brands for various “health situations,” like using the unapproved phrase “probiotic culture of Kombucha” on the label, conducting unauthorized alcohol fermentation and manufacturing the kombucha at a different address then what was provided to INVIMA. .
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Kombucha Brewers International (@kombuchabrewers KBI) released a statement supporting kombucha brewers. The statement reads: “Kombucha is an incredibly safe product to brew at home as well as commercially. As a traditional fermented food, it’s microbial makeup and the organic acids it produces ensures that it is well preserved even without refrigeration. The role of fermented foods far precedes other types of preservation technology such as refrigeration, pasteurization or chemical preservatives. …Colombia has a long history of using fermented foods to provide nutrient dense foods for their native population. Cassava, cacao and maize have all been fermented through traditional processes to create almidón agrio, chicha, champús, masa agria, guarapo and many more.”

Read more (KBI)

Researchers in China found probiotics from lactobacilli bacteria in traditional Chinese pickles prevent dental cavities. The study, published in the journal “Frontiers in Microbiology,” evaluated 14 different types of Sichuan pickles from southwest China. Of the 14 pickles, 54 Lactobacilli strains were detected. But only one  (plantarum K41) was found to significantly reduce “the incidence and severity of cavities.” The strain reduced the cavity-causing Streptococcus mutans bacteria by 98.4%. The S. mutans bacteria is found in plaque on human teeth.

According to the study: “Pickles are an integral part of the diet in the southwest of China. When fruits and vegetables are fermented, healthy bacteria break down the natural sugars. These bacteria, also known as probiotics, not only preserve foods but offer numerous benefits, including immune system regulation, stabilization of the intestinal microbiota, reducing cholesterol levels, and now inhibiting tooth decay.”

Read more (Science Daily