Brewing beer leads to production of many waste streams such as spent grain and spent brewer’s yeast. Efforts have been made to repurpose the brewer’s spent grain for use in animal feed, biofuel production, or simply compost, but in many cases, this spent grain ends up in landfills. However, researchers from Singapore’s Nanyang Technological University have created a process to extract >80% of available protein to create a protein isolate. Around 200 grams of protein can be isolated from 1 kilogram of spent grain. To isolate, the spent grain is first sterilized before being fermented by Rhizopus oligosporus, a fungus commonly used to produce tempeh. This fermentation increases the protein extractability in the grain. The researchers use microwave-assisted three-part partitioning to extract and separate proteins and increase their antioxidant activity. Read more here. In addition to brewer’s spent grain, spent brewer’s yeast is another large waste stream generated during the brewing process.

Spent brewer’s yeast is the leftover dead yeast post-fermentation. This can be used to make marmite and is a common additive in pet food. A recent application used spent brewer’s yeast to filter metals of electronic waste from waste streams. Spent brewer’s yeast can be dried and used to allow metal ions to adsorb to the surface due to electrostatic interactions. Through acid treatment, metals can be removed from the yeast surfaces and then recycled. The yeast can also be reused to recover different metals.

What are your thoughts on the applications for repurposing these brewing waste streams?

Image From: Precision Fermentation

Global demand for more sustainable/healthy protein sources (vs. red meat) have driven the market growth of Plant-Base Meat Alternatives (PBMA). However, developing products that replicate red meat’s unique flavors, aromas and textures has been challenging for many producers. A group of researchers set out to determine if fermented onions, chives and leeks could produce these highly sought after meat flavors/aromas. In the study, the scientists fermented a variety of fungal species with various food categories/types. What was discovered was that meaty flavors/aromas could be produced via fermentation from foods in the Allium family (such as onions and leeks) and the fungus that produced the most favorable meaty flavors/aromas was Polyorus umbellatus. You can read a summary of this study via a link to the website. After further analysis, it was determined that one of the primary chemicals that produced these favorable results (from fermentation of onions/leeks with Polyorus umbellatus) was bis(2-methyl-3-furyl)disulfide. The full study can be reviewed via the Scientific journal publication. Additionally, other similar publications highlighted the challenges of reproducing the complex sensory flavor/aroma profiles of red meat. To achieve larger acceptability of PBMAs from meat eaters (and not just vegetarians and vegans), the new generation of PBMAs must resemble the texture/appearance/aroma/taste of authentic meat products. Reproducing this using PBMAs can be immensely challenging. This scientific journal entry can be found here. What are your thoughts how fermentation can help solve the challenges of reproducing the complex taste/aroma sensory profiles of traditional red meat?

Garlic fermentation is an interesting topic that has been previously discussed in a prior posting, but have you heard of black garlic? This product is fresh garlic that has been fermented in a high-humidity environment at a high temperature for a period of time. As fermentation occurs, the cloves begin to darken and the texture changes to a squishy or jellylike consistency. This product has a sweet taste. Black garlic has been eaten for centuries in South Korea, Japan, and Thailand (Kimura et al., 2016). 

Black garlic demonstrates health benefits as well. We discussed in class how fermentation can change the bioavailability of some nutrients. It appears this is the case in garlic as well. Researchers have found high levels of water-soluble antioxidants compounds (S-allyl cysteine, S-allyl-mercapto cysteine), 5-hydroxymethylfurfural, organosulfur compounds, polyphenol, and volatile compounds in black garlic compared to fresh garlic after thermal processing. The bioactive compounds in black garlic demonstrate several biological properties, such as anti-oxidation, anti-inflammation, anti-obesity, hepatoprotection, hypolipidemia, anti-cancer, anti-allergy, immunomodulation, nephroprotection, cardiovascular protection, and neuroprotection (Ahmed and Wang, 2021). 

An analysis using Illumina MiSeq sequencing technology provided information about the bacterial community present in black garlic production. During the analysis, 45 phyla and 1125 distinct genera were found in the bacterial community. The four genera that were most abundant were Thermus, Corynebacterium, Streptococcus, and Brevundimonas. The study also investigated important fermentation processes. It was found that membrane transport, carbohydrate metabolism, and amino acid metabolism were important processes for black garlic fermentation (Qiu et al., 2018).  

Have you heard of or seen black garlic before? Would you be interested in incorporating it into your diet for its health benefits? 

Photo Credit – Jacek Halicki

Low- and no-alcohol (NA) beers are a unique and growing trend in the alcoholic fermented beverages industry. An article from Forbes Magazine tracked the rise in consumption of these products during the “Dry January” period. The article states that in 2019 only 5% of Dry January participants drank NA beers but that number increased to 29% by January 2022 (Dingwall, 2022). This is a significant increase in the market share for these low and NA beers. Popular NA beer brands are popping up across the country, check out prominent ones like  Athletic Brewing Co. and Best Day Brewing. Researchers have found that the main factors that motivate consumers to purchase these products are perceptions that alcohol has negative health effects and as a decision for weight management (Staub, 2022). To produce these products, breweries have an additional processing step following the completion of the fermented beer. This step, which removes or reduces the ethanol present in the beer is called “de-alcoholization” (Catarino, 2011). There are multiple strategies for this separation, including evaporation and distillation, and membrane-based methods like reverse osmosis and filtration, as well as simple centrifugation (Catarino, 2011).

Have you heard of or tried low- or NA beers? What sensory and flavor characteristics do you think might differ in these products when compared to regular, alcohol-containing beer? Do you think this trend is going to catch on with craft breweries – if not, what could make this difficult?

Image Credit: Brewer’s Association

Scientists, academics and researchers at Stanford University recently set out to investigate the effects of  high fermented food diets on human gut microbiome diversity. In addition, these researchers wanted to directly compare these impacts to high fiber diets (non fermented foods). During the study, 36 healthy adults were randomly assigned to a 10-week diet that included either fermented or high-fiber foods. You can read a summary of this study via a link to the website. The study had two primary findings. The first finding was high fermented foods had high positive impacts to microbiome diversity. With this increase in microbiome diversity, reduced inflammation markers were observed consistently across all participants in the study who were assigned to the higher fermented food group (which may help individuals who are facing chronic inflammatory diseases). The second finding was that the high fiber groups’ microbiomes remained stable (little to no change). The full study can be reviewed via the scientific journal publication. Additionally, other publications studied both the short term and long term gut microbiome impact that diets high in fermented foods may have. It was found that gut microbiome diversity can be positively impacted in both the short term as well as the long term- stated differently, gut microbiome diversity can be impacted quickly and for the long term (if the diet is continued).  This scientific journal entry can be found here. What are your thoughts on the largest benefits that diets high in fermented foods can bring to the average adult?

Photo Credit: Janelle Weaver, med.standord.edu

The Inuit, an indigenous population of the Arctic region, have a long history of fermenting a variety of foods. Some of these foods are made from fermenting sea mammals, especially seals, which are said to be the foundation of their diet. A wide variety of foods can be made from fermenting seal, and there are also multiple methods for accomplishing this. For example, some may ferment the entire carcass, or they may ferment different parts of the seal (flippers, blubber, etc.) in bags made from the seal’s stomach. Different species of seals are used, as well as walrus and narwhal. Birds are also fermented, and may include the intestines, the whole bird, or even their eggs. A food that is less common, but is still considered a delicacy by some, is the fermented contents of a caribou’s stomach (Hauptmann, 2021). Alaska has the highest number of cases of botulism in the United States. It is believed that this is in part due to the fermented foods that are consumed by the Inuit people. The CDC attributes fermented fish heads, fermented fish eggs, fermented beaver tail, fermented seal flipper, fermented walrus flipper, fermented whale, and seal oil to be some of the culprits for botulism cases in those that have eaten traditional Alaskan Native food. There have been researchers, such as Eric Johnson, working on ways to combat this issue. He believes Clostridium, which is the genus where the causal agent of botulism can be found, may inhabit small pockets of water found within the fat of animals used in fermentation. These pockets would be released as the fat is broken down. He hopes to find a way to neutralize or prevent this problem (Tyrrell, 2017). While he mainly works with seal oil, this could likely be extrapolated to help with other fermented products. An important note to this research is the balance of traditional practices and helping to make these practices safer. 

Would you be willing to try these traditional Inuit fermented foods?

Photo by Daniel Hauptmann (©Aviaja Hauptmann)

The photo is of a seal carcass that is being used to ferment sea birds. You can see the bird placement drawn in. The carcass is then buried and covered in rocks to ferment.

Fermented foods, with a history spanning nearly 10,000 years, exhibit significant diversity in the 21st century. Each fermented food harbors a unique microorganism population, and when consumed, nutrients and microorganisms may persist to interact with the gut microbiome. This review explores key food fermentation pathways, the role of microorganisms, potential health benefits, and the ability of fermented foods to influence the gut microbiome.

In food fermentation, microorganisms release amino acids and bioactive peptides from proteins, convert fats into healthier forms like conjugated linoleic acid, and generate diverse metabolites such as short-chain fatty acids (SCFA), vitamins, exopolysaccharides, and gamma-aminobutyric acid. These compounds influence the sensory attributes and health-promoting qualities of the fermented food product demonstrated in the article. Many fermented foods, with microbial populations reaching up to 10^8 colony-forming units per gram (CFU/g), are consumed without further processing. These microorganisms have the capacity to enter the human gastrointestinal tract, participating in interactions and potentially becoming essential components of the gut microbiome detailed in the paper.

In summary, the potential of fermented foods to influence the gut microbiome post-consumption arises from compounds generated during fermentation or through interactions with microorganisms present in the fermented food that can endure the journey through the gastrointestinal tract.

What is your favorite fermented food and how do you feel it benefits your health? Do you have knowledge about the connection between gut microbiome and human health? Will you consider continuing to consume fermented foods after reading this paper?

image source: admin

We’ve acquired knowledge about various fermented foods both from our classes and previous posts. In this post, I want to expand on this topic by introducing more examples of fermented foods and their associated benefits.

1. Kvass: A traditional fermented beverage originating from Eastern Europe, typically made from rye bread, kvass is rich in probiotics, B vitamins, and beneficial enzymes. It may support digestion, improve nutrient absorption, and boost immunity. This paper has detailed information about the health effects of kvass.
2. Fermented Soy Sauce: Produced through the fermentation of soybeans, wheat, salt, and a fermenting agent called koji, fermented soy sauce is rich in amino acids, antioxidants, and beneficial bacteria. It adds flavor to dishes while potentially improving digestion and supporting cardiovascular health.
3. Fermented Tofu (Fuyu, as in the picture): A traditional Chinese and Southeast Asian food, fermented tofu undergoes fermentation with various molds and bacteria, resulting in a creamy texture and distinctive flavor. It’s a good source of protein, calcium, and iron, and it may aid digestion and support bone health. This paper talked about the quality of the fermented tofu.
4. Fermented Fish Sauce: Widely used in Southeast Asian cuisine, fish sauce is made by fermenting fish and salt. It’s rich in amino acids, minerals, and vitamins, and it adds depth of flavor to dishes while potentially enhancing digestion and nutrient absorption.
5. Fermented Vegetables: Besides kimchi and sauerkraut, many other vegetables can be fermented, including carrots, beets, and peppers. Fermented vegetables are rich in fiber, vitamins, and beneficial bacteria, promoting gut health, enhancing immunity, and supporting overall well-being.
6. Fermented Hot Sauce: Hot sauces made from fermented chili peppers contain probiotics and beneficial enzymes, in addition to capsaicin, the compound responsible for their heat. Consuming fermented hot sauce may support digestion, boost metabolism, and provide antioxidant benefits.
7. Fermented Beverages (Cider, Wine, Beer): Alcoholic beverages like cider, wine, and beer are produced through the fermentation of fruit or grains by yeast. While moderate consumption of alcoholic beverages may have health benefits such as improved heart health and antioxidant effects, excessive intake can have adverse effects. This paper has detailed information about the health effects of cider.
8. Nattozuke (Fermented Vegetables with Natto): A traditional Japanese dish, nattozuke is made by fermenting vegetables like cucumber or daikon radish with natto, a fermented soybean product. It combines the benefits of both fermented vegetables and natto, providing probiotics, vitamins, and minerals.
9. Fermented Dairy Alternatives (Coconut Yogurt, Almond Milk Yogurt): Fermented dairy alternatives offer probiotics and nutrients similar to traditional dairy yogurt. They are suitable options for individuals with lactose intolerance or dairy allergies and may support gut health and provide essential nutrients.

Given the abundance of fermented foods worldwide, which one captures your preference? Are you acquainted with any of the lesser-known fermented delicacies? Would you be open to trying some of these less common foods?

image source:Cathy Erway

As discussed in class, galactose plays a key role in the browning reaction observed in cheese products. In detail, browning occurs through an intricate interaction(Maillard reaction) between reducing sugars, like galactose, and amino acids released from protein breakdown. In this post, I aim to delve deeper into the potential implications of the browning reaction on human health.

Browning reactions that happen in food can generate chemical compounds leading to cancer.

Cheese browning typically occurs before it is served to the customer through heating. The compounds generated during these browning reactions can pose risks to human health (Gulland, 2017). These reactions contribute to the formation of carcinogens such as heterocyclic amines and polycyclic aromatic hydrocarbons (Bhargava et al., 2004; Sugimura et al., 2004). Furthermore, acrylamide, a well-documented carcinogen, forms from sugars and amino acids (primarily asparagine) in heated food items when temperatures surpass 120°C (Becalski et al., 2003). These heat-induced carcinogens elevate the likelihood of stomach and colorectal cancers.

Why do we still need browning in cheese products? 

While it’s true that browning reactions in food can produce carcinogenic compounds, such reactions are often desired for their impact on flavor, texture, and appearance. In the case of cheese, browning, also known as the Maillard reaction, can enhance the taste and aroma, creating a desirable flavor profile. Another point is that while these compounds may pose potential health risks, the levels generated from moderate consumption of browned cheese are generally not considered significant enough to cause harm to human health. Additionally, the body’s natural detoxification processes can help mitigate the impact of these compounds. Additionally, the visual appeal of golden-brown cheese can make it more appetizing to consumers. It’s important to note that the degree of browning and the associated formation of harmful compounds can vary depending on factors such as cooking temperature, duration, and ingredients used. Food safety guidelines and recommendations often advise moderation and careful monitoring of browning processes to minimize the formation of potentially harmful compounds while still achieving the desired culinary outcomes. My recently published paper also demonstrated some benefits to human gut health due to the browning reaction that happens in foods.

Besides browning, fermentation provides a special flavor during cheese production. 

The fermentation process involves the conversion of lactose (milk sugar) into lactic acid by bacterial cultures, typically including strains of Lactobacillus and other beneficial microorganisms. This acidification not only helps in coagulating the milk proteins to form curds but also contributes to the development of complex flavors and textures in cheese. During fermentation, these bacterial cultures produce various compounds that contribute to the unique taste and aroma of cheese. For example, certain bacteria produce enzymes that break down proteins and fats, releasing flavorful compounds such as amino acids and fatty acids. Additionally, the metabolic activities of bacteria can produce compounds like diacetyl, which imparts a buttery aroma, and acetoin, which contributes to a creamy taste.

Generally, both fermentation and browning can impart distinctive flavors to cheese products. Browning reactions, typically induced by heating, may potentially lead to adverse effects on human health. However, fermentation, which involves the participation of microbial cultures, can potentially result in beneficial effects on human health. Have you ever thought about the influence of browning reactions on food materials? Which flavor do you favor: the original taste of the cheese or the flavor that develops through browning?

image source: Maanvi Singh