An Irresistible Appeal

Scientists at Caltech , using fermented juice as bait have discovered that a fruit fly can travel six million times its body length in search of food. 

Flies were lured by “a tantalizing cocktail of fermenting apple juice and champagne yeast  produces carbon dioxide and ethanol, which are irresistible to a fruit fly.” Scientists released buckets of fruit flies on a dry lakebed in California’s Mojave Desert, far away from any other tempting food source. 

The team is studying how far the flies would travel to a food source. Certain species of fruit flies are invasive and can cause significant agricultural damage. Their results will be published in the April issue of Proceedings of the National Academy of Sciences.

Read more (Caltech)

Scientists in Russia and Egypt have developed a functional drink that’s been proven to combat anemia and malnutrition. The juice is made from beet extract, milk and probiotic bacterial strains. The scientists developed a quinoa bread, too. The goal is to keep the beverage and bread affordably priced and get them offered at grocery stores internationally.

“One should bear in mind that we are not creating a medicine, but a natural, functional food product,” said Sobhi Ahmed Azab Al-Suhaimi, professor in the Department of Technology at South Ural State University (SUSU) in Russia. “However, this juice can make up for the lack of iron, zinc, manganese and calcium in the body. One serving of the drink will contain the whole rate [sic] of minerals. Its carbohydrate content is low. Fermented juice will help to overcome anemia and to improve digestion due to probiotics.”

Scientists at SUSU worked with scientists at the University of Alexandria in Egypt. Their findings were published in the Journal of Food Processing and Preservation and Plants.

Read more (Phys.org)

Leaders in the biotechnology industry are calling fermentation “Agricultural 2.0.” As consumers continue to seek alternative protein and dairy options, more biotech companies are using fermentation to produce alt-proteins. Ricky Cassini, co-founder and CEO of natural food colourant start-up Michroma, says: “The fermentation space is thriving and there is a lot of progress around this technology.”

Here are three expected developments in  fermentation processing  this year:

  1. More dairy-free cheese products will enter the market.
  2. Price points for alternative proteins will drop as more players enter the market.
  3. Regulatory issues and naming conventions will gain in significance.

Read more (Food Navigator)

Love the rich flavor of chocolate? Thank microbes. Scientists are researching how fermentation affects the flavor of chocolate. An article in Scientific American details how a giant cacao seed pod naturally ferments. 

Cacao has a wild fermentation, meaning the farmers who harvest the pods “rely on natural microbes in the environment to create unique, local flavors.” Just as grapes take on regional terroir (the characteristic flavor imparted by a place), “these wild microbes, combined with each farmer’s particular process, confer terroir on beans fermented in each location.” Demand for high-quality cacao beans is growing, and producers who make small-batch chocolate with distinctive flavors also are seeing sales growth.

Read more (Scientific American)

Fermenting — in Space?

Microbes that coexist on plants influence a crop’s size, shape, color, flavor and yield. What would these microbes do in microgravity? The International Space Station (ISS) is testing to find these results. 

Flight engineer Shannon Walker (pictured) shows sample bags collected for the Grape Juice Fermentation in Microgravity Aboard ISS study. Astronauts will observe the fermentation process, measuring microbial differences. Back on earth, a matching, control sample is being observed in an environmental control chamber that mimics the ISS ambient temperature. The space and earth samples then will be analyzed for changes. Both flight and ground control samples are analyzed post-investigation for genetic change.

Read more (NASA)

A new study on kefir found that the individual dominant species of Lactobacillus bacteria in kefir grains cannot survive in milk on their own. The bacteria need one another to create the fermented dairy drink, “feeding on each other’s metabolites in the kefir culture.”

The research, conducted by EMBL (Europe’s laboratory for life and sciences) and Cambridge University’s Patil group and published in Nature Microbiology, illustrates a dynamic of microbes that had eluded scientists. Though scientists knew microorganisms live in communities and depend on each other to survive, “mechanistic knowledge of this phenomenon has been quite limited,” according to a press release on the research.

“Cooperation allows them to do something they couldn’t do alone,” says Kiran Patil, group leader and author of the paper. “It is particularly fascinating how L. kefiranofaciens, which dominates the kefir community, uses kefir grains to bind together all other microbes that it needs to survive — much like the ruling ring of the Lord of the Rings. One grain to bind them all.”

To make kefir, it takes a team. A team of microbes.

The group studied 15 samples of kefir, one of the world’s oldest fermented food products. Below are highlights from a press release on the published results. 

A Model of Microbial Interaction

Kefir first  became popular centuries ago in Eastern Europe, Israel, and areas in and around Russia. It is composed of ‘grains’ that look like small pieces of cauliflower and have fermented in milk to produce a probiotic drink composed of bacteria and yeasts.

People were storing milk in sheepskins and noticed these grains that emerged kept their milk from spoiling, so they could store it longer,” says Sonja Blasche, a postdoc in the Patil group and an author of the paper. Because milk spoils fairly easily, finding a way to store it longer was of huge value.”

To make kefir, you need kefir grains, which must come from another batch of kefir. They cannot be made artificially. The grains are added to milk, to ferment and grow. Approximately 24 to 48 hours later (or, in the case of this research, 90 hours later), the kefir grains have consumed the available nutrients. The grains have grown in size and number, and are removed and added to fresh milk — to begin the process anew.

For scientists,  kefir is more than just a healthy beverage: it’s an easy-to-culture model microbial community for studying metabolic interactions. And while kefir is quite similar to yogurt in many ways – both are fermented or cultured dairy products full of ‘probiotics’ – kefir’s microbial community is far larger, including not just bacterial cultures but also yeast.

A “Goldilocks Zone”

While scientists know that microorganisms often live in communities and depend on their fellow community members for survival, mechanistic knowledge of this phenomenon has been quite limited. Laboratory models historically have been limited to two or three microbial species, so kefir offers – as Patil describes – a ‘Goldilocks zone’ of complexity that is not too small (around 40 species), yet not too unwieldy to study in detail.

Blasche started this research by gathering kefir samples from several sources. Though most  were obtained in Germany, they may have  originated elsewhere, grown from kefir grains  passed down through the years..

“Our first step was to look at how the samples grow. Kefir microbial communities have many member species with individual growth patterns that adapt to their current environment. This means fast- and slow-growing species and some that alter their speed according to nutrient availability, Blasche  says. This is not unique to the kefir community. However, the kefir community had a lot of lead time for coevolution to bring it to perfection, as they have stuck together for a long time already.”

Cooperation is key

Finding out the extent and nature of  cooperation among kefir microbes was far from straightforward. Researchers combined a variety of state-of-the-art methods, such as metabolomics (studying metabolites’ chemical processes), transcriptomics (studying the genome-produced RNA transcripts) and mathematical modelling. These processes  revealed not only key molecular interaction agents like amino acids, but also the contrasting species dynamics between  grains and  milk.

“The kefir grain acts as a base camp for the kefir community, from which community members colonise the milk in a complex yet organised and cooperative manner,” Patil says. “We see this phenomenon in kefir, and then we see it’s not limited to kefir. If you look at the whole world of microbiomes, cooperation is also a key to their structure and function.”

In fact, in another paper from Patil’s group (in collaboration with EMBL’s Bork group) in Nature Ecology and Evolution, scientists combined data from thousands of microbial communities across the globe – from in soil to in the human gut – to understand similar cooperative relationships. In this second paper, the researchers used advanced metabolic modelling to show that the co-occurring groups of bacteria, groups that are frequently found together in different habitats, are either highly competitive or highly cooperative. This stark polarization hadn’t been observed before, and sheds light on evolutionary processes that shape microbial ecosystems. While both competitive and cooperative communities are prevalent, the cooperators seem to be more successful in terms of higher abundance and occupying diverse habitats — stronger together!

Chocolate’s Beer Roots

Chocolate beer sounds like a faddish flavor, but its roots run deep. Pre-Columbian Mesoamericans fermented cacao fruit to make a beer-like drink called chicha.

Chicha is usually made from corn, but there are regional variations made from other new-world plants like potatoes, peanuts and cacao beans,” reads an article from The Seattle Times. Chicha was studied by archaeology professors at Cornell and Berkeley who found “The roots of the modern chocolate industry can be traced back to this primitive fermented drink.”

Read more (The Seattle Times)

Primates & Fermented Food

Humans have been fermenting for thousands of years; now, an anthropologist has published evidence that several other primate species also feed on fermented food.

Katherine Amato, at Northwestern University, compiled evidence from 151 biologists who study the feeding habits of 40 primate species from Asia, Africa and the Americas. Fifteen of those species consume fruit in the late stages of fermentation, and thatermented fruit makes up 3% of their diet. Though the scale is small, the evolutionary roots are interesting. 

“Of the 44 types of fruit eaten in an advanced state of fermentation, 16 had tough husks that the animals could not easily open unless they were first fermented, and 25 contained digestion-impeding or toxic chemicals like tannins and alkaloids that fermentation tends to destroy,” reads an article in The Economist on the research. 

It continues: “Several of the fermented-fruit-eating primates alive today split off from the line that leads to people well over 10m years ago. Presumably, they have evolved their own genetic arrangements for dealing with fermentation products and the microbes that produce them. Nevertheless, Dr. Amato’s work suggests that human beings’ love of the fermented does, indeed, have deep evolutionary roots.”

Read more (The Economist)

Do probiotic supplements deliver the same benefits as fermented foods? Dr. Gail Cresci says to be leery of prebiotic and probiotic pills.

“There are challenges to keeping microbes viable in encapsulated tablets,” says Cresci, director of Nutrition Research for the Cleveland Clinic’s Department of Pediatric Gastroenterology, Hepatology and Nutrition. “It’s also very, very important to know that each strain of bacteria is not the same as the next. For example, lactobacillus has hundreds of different strains, and each one may behave differently. People like to use supplements because they like to think one size fits all, but it doesn’t.”

“Take in prebiotics and probiotics through food sources. Yogurt with added probiotic bacterial strains is much better to consume than supplements also because as it’s been waiting for you to eat it, it’s been producing more beneficial metabolites. When you eat it, you get all that.”

Read more (American Heart Association/U.S. News & World Report)

After Dr. Bob Hutkins finished a presentation on fermented foods during a respected nutrition conference, the first audience question was from someone with a PhD in nutrition: “What are fermented foods?”

“I thought ‘Doesn’t everyone know what fermentation is?’ I realized, we do need a definition. Those of us that work in this field know what we’re talking about when we say fermented foods, but even people trained in foods do not understand this concept,” says Hutkins, a professor of food science at the University of Nebraska-Lincoln. He presented The New Definition of Fermented Foods during a webinar with TFA

Hutkins was part of a 13-member interdisciplinary panel of scientists that released a consensus definition on fermented foods. Their research, published this month in Nature Reviews Gastroenterology & Hepatology, defines fermented foods as: “foods made through desired microbial growth and enzymatic conversions of food components.”

“We needed a definition that conveyed this simple message of a raw food turning into a fermented food via microorganisms,” Hutkins says. “It brings some clarity to many of these issues that, frankly, people are confused about.”

David Ehreth, president and founder of Alexander Valley Gourmet, parent company of Sonoma Brinery (and a TFA Advisory Board member), agreed that an expert definition was necessary.

“As a producer, and having started this effort to put live culture products on the standard grocery shelf, I started doing it as a result of unique flavors that I could achieve through fermentation that weren’t present in acidified products,” Ehreth says. “Since many of us put this on our labels, we should be paying close attention to what these folks are doing, since they are the scientific backbone of our industry.”

Hutkins calls fermented foods “the original shelf-stable foods.” They’ve been used by humankind for over thousands of years, but have mushroomed in popularity in the last 15. Fermented foods check many boxes for hot food trends: artisanal, local, organic, natural, healthy, flavorful, sustainable, innovative, hip, funky, chic, cool and Instagram-worthy.

Nutrition, Hutkins hypothesizes, is a big driver of the public’s interest in fermentation. He noted that Today’s Dietitian has voted fermented foods a top superfood for the past four years. 

Evidence to make bold claims about the health benefits of fermentation, though, is lacking. Hutkins says there is observational and epidemiological evidence. But randomized, human clinical trials — “the highest evidence one can rely on” — are few and small-scale for fermented foods. 

Hutkins shared some research results. One study found that Korean elders who regularly consume kimchi harbor lactic acid bacteria (LAB) in their GI tract, providing compelling evidence that LAB survives digestion and reaches the gut. Another study of cultured dairy products, cheese, fermented vegetables, Asian fermented products and fermented drinks found that most contain over 10 million LAB per gram. 

Still, the lack of credible studies is “a barrier we have to get past,” Hutkins says. There are confirmed health benefits with yogurt and kefir, but this research was funded by the dairy industry, a large trade group with significant resources. 

“I think there’s enough evidence — most of it through these associated studies — to warrant this statement: fermented foods, including those that contain live microorganisms, should be included as part of a healthy diet.”