Advances in Yeast

We’re in the midst of a yeast revolution, as genome sequencing creates opportunity for cutting-edge advances in fermented foods and drinks. Yeast will be at the forefront of innovation in fermentation, for new flavors, better quality and more sustainability.

“Understanding and respecting tradition is a key part of this. These practices have been tested for hundreds and thousands of years and they cannot be dismissed. There’s a lot the science can learn from tradition,” says Richard Preiss of Escarpment Laboratories. Priess was joined by Ben Wolfe, PhD, associate professor at Tufts University (and TFA Advisory Board member), during a TFA webinar, Advances in Yeast

Preiss continues: “There’s still a place for innovation, despite such a long history of tradition with fermentation. A lot of the key advances in science are literally a result of people trying to make fermentation better.”

Wolfe, who uses fermented foods and other microbial communities to study microbiomes in his lab at Tufts, said “there’s this tradition versus technology conflict that can emerge.” 

“I tell my students when I teach microbiology that much of the history of microbiology is food microbiology, it is actually food microbes, and they really drove the innovation of the field so it really all comes back to food and fermentation,” Wolfe says.

The technology relating to the yeasts used in fermentation has expanded enormously over the last decade, due heavily to advances in genome sequencing. Studying genetics allows labs like the ones Priess and Wolfe run to find the genetic blueprint of an organism and apply it to yeast. Drilling down further, they can tie genotype to phenotype to determine characteristics of a yeast strain. This rapidly expanding technology will disrupt and advance fermentation. 

Priess predicted three areas of development for yeast fermentation in the coming years:

  1. Novelty Strains

Consumers have accelerated their acceptance of e-commerce during the Covid-19 pandemic and they’ll do the same for biotechnology, Priess says.

“Our industry does thrive on novelty,” he adds, noting there are beer brands already creating drinks with GMO yeast. “Craft beer is going to be the first food space where the use of GMOs is widespread — we’re seeing that play out a lot faster than I ever thought it would be with some of these products already on the market. Novelty does have value.”

Wolfe noted many consumers shudder at the idea of a GMO food or beverage, but microbes in beer are dead. Consumers are not drinking a living GMO in beer. 

Yeasts also already pick up new genetic material naturally, through a process called gene transfer.

“It’s part of the evolutionary process that all microbes go through,” Wolfe says. “From my own lab and from other labs, cheese and sauerkraut and all these other fermented foods are showing so much genetic exchange that’s already happening.”

  1. Climate Change

The food industry must address growing concerns about climate change. Priess predicts breeding plants — like barley, hops and grapes — that are more drought-tolerant, or even using yeast technologies to increase yields or the rate of fermentation.

“Craft beer is massively wasteful,” Priess says. It takes between three to seven barrels of water to make one barrel of beer. “It is something we’re going to have to reckon with the next 10 years.” 

Yogurt and cheese, too, produce large amounts of waste products.

  1. Ease of Genomics

The cost and time of genome sequencing has reduced significantly. It used to cost thousands of dollars and take many weeks to document a yeast genome. Now, it can be done for $200 in only a few days.

“The tools to deal with the data and get some meaning from it have never been more accessible. It’s incredibly powerful,” Priess says. “We’re developing solutions for products without millions of dollars.”

Priess does not agree with companies patenting yeasts, “it’s murky territory.” He believes fermentation and science should be about collaboration, not ownership and protection.

“Working with brewers and other fermentation enthusiasts, it’s this incredibly open and collaborative space compared to a lot of the industries,” he says. “I think that’s like our secret weapon or our secret value is that fermentation is so open in terms of access to knowledge as well as in terms of people being willing to experiment and try new things. That’s how it’s able to develop so quickly.”

Is there a connection between a happy gut and a healthy heart? The University of North Florida Department of Nutrition and Dietetics is conducting a study to determine what impact a diet rich in fermented vegetables has on cardiovascular disease and markers of inflammation.

Participants will be placed in two groups — the first consumes their regular diet for eight weeks, then receives fermented vegetables at the end of the study. The second will eat a half cup of fermented vegetables every day for eight weeks.

 “These studies are the only way nutritionists can determine if certain foods can help with prevention and/or treatment of common health problems faced by our community, such as cardiovascular disease,” says Dr. Andrea Arikawa, associate professor at the university.

Read more (University of North Florida)

Adding to the growing research on fermentation and its impact on coffee’s flavor, food corp Nestlé released their own study on the link between coffee and fermentation. Scientists found that the length of time coffee cherries (or beans) are fermented is key to final flavor. They plan to use their findings to “tailor specific fermentation conditions to different coffee varieties, allowing us to highlight new distinct natural flavors and sensorial notes.”

“While several favors affect coffee quality, we showed a subtle combination of specific fermentation conditions can lead to a modulation of the sensory properties of the final cup, opening new avenues to differentiate coffee taste in a fully natural way,” said Cyril Moccand, a scientist at Nestlé Research who led the study. 

On August 11, The Fermentation Association will host a webinar with the Specialty Coffee Association “The State of the Art in Coffee Fermentation.”

Read more (Beverage Daily)

A new peer-reviewed study from researchers at the University of Illinois and Ohio State University found 66% of commercial kefir products overstated probiotic count and “contained species not included on the label.”

Kefir, widely consumed in Europe and the Middle East, is growing in popularity in the U.S. Researchers  examined the bacterial content of five kefir brands. Their results, published in the Journal of Dairy Science, challenge the “probiotic punch” the labels claim.

“Our study shows better quality control of kefir products is required to demonstrate and understand their potential health benefits,” says Kelly Swanson, professor in human nutrition in the Department of Animal Sciences and the Division of Nutritional Sciences at the University of Illinois. “It is important for consumers to know the accurate contents of the fermented foods they consume.”

Probiotics in fermented products are listed in colony-forming units (CFUs). The more probiotics, the greater the health benefit. 

According to a news release from the University of Illinois: “Most companies guarantee minimum counts of at least a billion bacteria per gram, with many claiming up to 10 or 100 billion. Because food-fermenting microorganisms have a long history of use, are non-pathogenic, and do not produce harmful substances, they are considered ‘Generally Recognized As Safe’ (GRAS) by the U.S. Food and Drug Administration and require no further approvals for use. That means companies are free to make claims about bacteria count with little regulation or oversight.”

To perform the study, the researchers bought two bottles of each of five major kefir brands. Bottles were brought to the lab where bacterial cells were counted and bacterial species identified. Only one of the brands studied had the amount of probiotics listed on its label. 

“Just like probiotics, the health benefits of kefirs and other fermented foods will largely be dependent on the type and density of microorganisms present,” Swanson says. “With trillions of bacteria already inhabiting the gut, billions are usually necessary for health promotion. These product shortcomings in regard to bacterial counts will most certainly reduce their likelihood of providing benefits.”

The news release continues:

When the research team compared the bacteria in their samples against the ones listed on the label, there were distinct discrepancies. Some species were missing altogether, while others were present but unlisted. All five products contained, but didn’t list, Streptococcus salivarius. And four out of five contained Lactobacillus paracasei.

Both species are common starter strains in the production of yogurts and other fermented foods. Because those bacteria are relatively safe and may contribute to the health benefits of fermented foods, Swanson says it’s not clear why they aren’t listed on the labels.

Although the study only tested five products, Swanson suggests the results are emblematic of a larger issue in the fermented foods market.

“Even though fermented foods and beverages have been important components of the human food supply for thousands of years, few well-designed studies on their composition and health benefits have been conducted outside of yogurt. Our results underscore just how important it is to study these products,” he says. “And given the absence of regulatory scrutiny, consumers should be wary and demand better-quality commercial fermented foods.”

Defining Postbiotics

As postbiotics continue to trend among consumers, the International Scientific Association for Probiotics and Prebiotics (ISAPP) released a consensus definition on the category, published in Nature Reviews: Gastroenterology & Hepatology.

The panel of international experts that created the definition made it clear that postbiotics and probiotics are fundamentally different. Probiotics are live microorganisms; postbiotics are non-living microorganisms. The published definition  states that postbiotics are a: “preparation of inanimate microorganisms and/or their components that confers a health benefit on the host.”

Inactive Microorganisms

A postbiotic could be whole microbial cells or components of cells, “as long as they have somehow been deliberately inactivated,” according to the news release by ISAPP. And a postbiotic does not need to be derived from a probiotic.

“With this definition of postbiotics, we wanted to acknowledge that different live microorganisms respond to different methods of inactivation,” says Seppo Salminen, professor at the University of Turku and the lead author of the definition. “Furthermore, we used the word ‘inanimate’ in favor of words such as ‘killed’ or ‘inert’ because the latter could suggest the products had no biological activity.”

The definition has been in the works for almost two years by authors from various disciplines in the probiotics and postbiotics fields. These include: gastroenterology, pediatrics, metabolomics, functional genomics, cellular physiology and immunology.

“This was a challenging definition to settle,” says Mary Ellen Sanders, ISAPP’s Executive Science Officer. “There are some who think that any purified component from microbial growth should be considered to be a postbiotic, but the panel clearly felt that purified, microbe-derived substances, for example, butyrate or any antibiotic, should just be called by their chemical names. We are confident we captured the essential elements of the postbiotic concept, allowing for many innovative products in this category in the years ahead.”

Growing Scientific Interest

Sanders continues: “The definition will be a touchstone for scientists, both in academia and industry, as they work to develop products that benefit host health in new ways. We hope this clarified definition will be embraced by all stakeholders, so that when the term ‘postbiotics’ is used on a product, consumers will know what to expect.”

Postbiotics have been on the market in Japan for years, and fermented infant formulas with added postbiotics are sold commercially in South America, the Middle East and in some European countries. ISAPP, in a release, notes: “Given the scientific groundswell, postbiotic applications are likely to expand quickly.”

The definition is the latest in a series of international consensus definitions by ISAPP. These include: probiotics, prebiotics, synbiotics and fermented foods.

  • Probiotics: Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.
  • Prebiotics: A substrate that is selectively utilized by host microorganisms conferring a health benefit.
  • Synbiotics: A mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host.
  • Fermented foods: Foods made through desired microbial growth and enzymatic conversions of food components.

Dairy-Free “Vegurt”

Chr. Hansen, a global bioscience supplier of ingredients, has developed Vega Culture Kits, a new line of probiotic starter cultures that can be used to create plant-based yogurt. “Vegurt,” a shortening of vegan or vegetarian yogurt, is the name being used for this non-dairy product. This term was created in reaction to the European Parliament’s current debate over whether plant-based products can use dairy-related terms like yogurt and milk.

“Vegurt seemed a catchy and suitable category name compared to having to sprain our tongues calling them ‘fermented plant-based alternatives to dairy yogurt,’” said Dr. Ross Critenden, senior director for commercial development at Chr. Hansen. 

The Vega Culture Kits are  designed to “robustly ferment” any dairy-free plant base, like nuts, cereals, legumes or seeds. The Vega Culture will appear as “culture” on ingredient lists, in the same way that dairy yogurts include “culture” when cultures or probiotic strains are added.

Read more (Food Navigator)

Syn-SCOBY

Engineers at MIT and the U.S. Army Research Lab have developed what they call Syn-SCOBY, a living material made from laboratory yeast and bacteria. Similar to a kombucha mother, it is a tough cellulose material that researchers say can be used to purify water and detect pollutants. They envision Syn-SCOBY being used in the biomedical field and for food applications. 

“We foresee a future where diverse materials could be grown at home or in local production facilities, using biology rather than resource-intensive centralized manufacturing,” said associate professor Timothy Lu, of MIT’s departments of biological engineering and electrical engineering and computer science.

Read more (MIT)

Thanks to lactic acid — which kills harmful bacteria during fermentation — fermented foods are arguably among the safest foods that humans eat. But if critical errors are made, there is the  risk of food safety hazards.

“When we talk about fruit and vegetable ferments, there is a very long history of microbial safety with traditionally fermented fruits and vegetables,” says Erin DiCaprio, extension specialist at University of California, Davis, Department of Food Science and Technology. “While outbreaks associated with fermented fruits and vegetables are rare, vegetable and fruit fermentation is not without risk.”

DiCaprio, a food safety expert, detailed proper food safety protocols during a webinar for EATLAC, a UC Davis project putting scientific knowledge and research behind fermentation. DiCaprio shared two documented instances of fermented foods causing a foodborne illness, both from small-scale batches of kimchi. But she emphasized that, when all food safety concerns are mitigated, fermented foods do not pose a risk.

“From the food microbiology standpoint, bacteria really are the most important group of microorganisms because bacteria, certain types of bacteria, are a food safety concern,” she adds. “There are many different types of bacteria that contribute to food spoilage and, of course, there are specific types of bacteria that are used beneficially for fermentation.”

What happens during fermentation that makes food safe? Lactic acid bacteria are created, which convert sugars into lactic acid, acetic acid and CO2. Those antimicrobial compounds help fight off pathogens, competing with other microbes for nutrition sources.

Biological hazards — bacteria, viruses and parasites that can cause foodborne illnesses — are the biggest concerns. Botulism, E. coli and salmonella are the main hazards for fermented foods. Botulism can form in oxygen-free conditions if a fermentation is not successful and acid levels are too low. E. coli and salmonella form when sanitation practices are not followed.

“Commercially, when someone is developing a valid fermentation process, they are typically going to be looking to see that sufficient acid is produced during fermentation, to inactivate some of these acid tolerant (bacteria),” DiCaprio says. “Our traditional vegetable fermentations — things like fermented cucumber, sauerkraut, kimchi — they’ve all been shown to produce sufficient acid to inactivate the sugar toxin producing e-coli, so from a safety standpoint, sufficient acid production is the critical control point for ensuring the safety of a fermented fruit or vegetable. “

There are seven critical factors to keep a ferment safe:

  1. High-quality, raw ingredients. “If there are a high number of spoilage microorganisms to start with, it will be really difficult for the lactic acid bacteria to dominate the fermentation,” DiCaprio says.
  • Research-based recipe. Following a tested recipe ensures the proper balance of ingredients to keep the food safe.
  • Proper sanitation. Cleaning of all utensils and surfaces ensures no pathogens will contaminate the food. This mitigates cross-contamination risk, too.
  • Preparation of ingredients. Food particles should be uniform in size, either cut in small slices or shredded. Smaller pieces release more water and nutrients, promoting the growth of lactic acid bacteria.
  • Salt concentration. Lactic acid bacteria thrive in a salt brine. The key amount: anywhere from 1-15% salt brine by weight of the ferment.
  • Appropriate temperature. A temperature between 65-75 degrees fahrenheit is ideal to keep spoilage microorganisms at bay.
  • Adequate time. “It takes a while for significant acid to be produced, so be patient and follow the directions in the recipe,” DiCaprio advises. Most fruit and vegetable ferments take 3-6 weeks to be completed.

Can you make wine with  lower alcohol content? Researchers at Washington State University think so. They are growing wild  in a lab to study how the yeasts behave and affect flavor and alcohol levels.

Yeasts used in winemaking — typically Saccharomyces — ferment by consuming the sugars in grapes, producing alcohol. If the grapes have higher sugar levels, they may produce wine with a higher alcohol percentage. But higher alcohol can have a range of negative consequences —  bitter taste, incomplete fermentation leaving residual sugar and even higher taxes for the winemaker. WSU researchers hope, by perfecting wild non-Saccharomyces yeast strains, they can help the state’s winemakers better control the fermentation process, and reap the benefits of lower alcohol percentages.

Read more (Daily Evergreen)

Archaeologists from NYU and Princeton have uncovered the world’s oldest industrial-sized brewery. Located in southern Egypt near the Abydos ruins, the facility dates from 3000 B.C. Many of Egypt’s early kings were born in Abydos, so it’s assumed the brewery made ceremonial beer for ritual offerings and royal funerals.

“The fundamental significance of the Abydos brewery is its scale relative to anything else in early Egypt,” project co-leader Dr. Matthew Adams said. The brewery likely produced about 22,400 liters with each batch (possibly weekly.) “That is a huge amount of beer by any standard, even in modern terms. It’s absolutely unique.”

Read more (Wine Spectator)