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From Tissue Culture to Table: A Closer Look at Texture and Flavor

Texture and flavor space


Orit (Host):

Hello everyone and thank you for joining us, we will start shortly. Let’s wait a few seconds to let people join in. Dorit, Eilam and Nico, are you with me? Great so let’s start!

Welcome to Steakholder Meets, the bi-weekly Twitter Space show brought to you by Steakholder Foods!

My Name is Orit Goldman, the VP Biology, and I will be hosting Steakholder Meets today. In this episode, I am excited to have Dorit Eliyaev, Eilam Golan and Nicolas Moreno, my colleagues and researchers at Steakholder Foods.

After our previous episodes where we talked about the cell, the source, the isolation, the growth, the characterization, and our challenges, the process from an isolated cell to a cell line, today we will go from the tissue culture to our table, and we will talk about the texture and flavor.

So, if you’re curious about the scientific side of this exciting topic, stay tuned with us! If you are joining us live, drop your questions as comments on our Q&A tweet. We will leave some time for Q&A at the end of the show to answer any questions you may have.

Dorit, Eilam and Nico, welcome! I am excited to have you here today. Maybe you can introduce yourself so people will know who you are and your background.

Dorit: Great. So I’m Dorit Eliyaev. I’m at Steakholder Foods for about three and a half years now. I have a master’s degree in, basically, science of medicine, sort of. But I have mastered cell isolation and cell culture and cell encapsulation in scaffolds, in tissue derived scaffolds. And now at Steakholder Foods, I’m mainly working on the fat tissue and on the fat cells.

Eilam: Hello, good evening, everybody. It’s a great day to be here today. Thank you for inviting me. My name is Eilam Golan, and I’m a mechanical engineer in biotechnology. I graduated from Tel Aviv University with a bachelor and master degree in mechanical engineering and biotechnology. Under the guidance of Dr. Elliott Lesman, I conducted an academic research for my master’s thesis, which focused on biomechanics and tissue engineering. After completing my studies, I was very fortunate to continue to work with my passion for engineering, physics and biology by joining Steakholder foods as a tissue engineer.

Nico: Hello. I’m Nicholas Moreno. I’m a food engineer at Steakholder Foods, I have seven years experience on development products for the food industry.

Orit:

Okay, thank you all. Let’s start with our first question: Why is it important to differentiate the cells? Dorit would you like to enlighten us with fat differentiation?

Dorit:

The cells we use are in a non-defined state, making them multi-potent, meaning they don’t play one role in the tissue. Cells in the meat we eat, on the other hand, are very specific in their characteristics in the tissue they inhabit. In order to “define” each cell and assign a role to it, we need to lead the cells down a path called ‘differentiation’. This process is crucial for the texture and taste of the product. Fat cells that went through differentiation have a distinctive taste and mouthfeel and contribute a lot to the juiciness of the meat. They also contribute to the smell while cooking the product.

Orit:

Thanks Dorit for helping us grasp the value of fat differentiation the benefits it provides to the meat. Eilam can you please give us additional information about muscle differentiation?

Eilam:

As Dorit mentioned, one of the key reasons why cell differentiation is crucial is to satisfy the desired sensory attributes of meat, such as taste, aroma, texture, and even visibility when developing whole cuts of meat.

Let’s start with taste, aroma, and visibility. Muscle cells contain proteins like myoglobin, which are contribute the flavor and aroma of meat. Myoglobin also gives meat its red color and contributes to the taste of fresh meat. This was just one example among many.

Moving on to texture, muscle cells also play a crucial role. Their unique fibrous structure gives meat its characteristic chewiness and mouthfeel. Proper differentiation of cells into muscle cells with the appropriate alignment and arrangement is essential to mimic the desired texture of conventional meat. Achieving the right texture is paramount to ensure that cultured meat products can be used in various culinary applications and meet consumer expectations.

Orit:

Now that we know that meat’s sensory qualities are influenced by its fat and muscle, how can we make sure that the cultivated proteins we use maintain the nutritional value of the original tissue? Eilam do you want to take the lead?

Eilam:

First and foremost, muscle cells are a primary source of high-quality protein in meat. Muscle cells contain proteins that are rich in essential amino acids, which are the building blocks of protein and are essential for our bodies’ growth, repair, and maintenance. Dorit you want to explain about fat…..

Dorit:

In addition to the flavor and juiciness that are directly sourced from the fat, we can also enjoy a high-quality nutritional value such as omega-3 and omega-6 fats that can be found in the meat. Furthermore, our body requires fat from nutrition to build healthy tissues, especially in the brain which consists of up to 60% fat. A big positive point for cultured fat is the possibility to control the fat composition, to some extent, allowing us to add the desirable fatty supplements and maybe subtract the undesirable fats from the final product.

Nico:

Cultivated proteins are a promising alternative to traditional animal products, but it’s important to ensure that they maintain the nutritional value of the original tissue. Here are some ways to achieve this: We can optimize the growth conditions. The nutritional composition of the final product is heavily influenced by the growth conditions of the cells. By optimizing the nutrient and environmental conditions for the cells, we can ensure that the final product is nutritionally similar to traditional meat.

Orit:

Let’s deep in the scientific part now. Dorit Eilam can you please explain to us the process of fat and muscle differentiation?

Dorit:

Nowadays there are two general categories of cell differentiation processes into fat cells- one of them includes chemical compounds like anti-inflammatory drugs and hormones that activate biological pathways in the cell to induce lipid droplet formation from different substrates that the cells take up from the growth medium, such as sugars and fatty acids. These chemical compounds are usually added to the growth medium and are not safe to eat. This protocol is mostly applied in academic research as proof of concept of adipo-differentiation.

The second category includes enriching the growth medium with substrates that induce formation of lipid droplets inside the cells. These substrates are often selected to be food grade, i.e. safe to eat, making this category much more attractive to the cultured meat industry and is also the process we apply at SteakHolder Foods. Once the cells produce lipid droplets within their cytoplasm, they start to grow in volume and swell up to contain as much fat as they can. The cells also produce triglycerides, just like the cells in the natural body of the animal. This process induces a self-positive feedback to produce more FFAs and more triglycerides.

Orit:

Eilam, what about muscle differentiation?

Eilam:

One approach for muscle differentiation is through the mimicry of the biochemical processes that occur during muscle development in vivo. This involves using a unique growth media and culture conditions that provide the necessary nutrients, and growth factors to guide the cells towards muscle cell differentiation.

In addition to these conventional methods, there are other physical stimulation methods, such as mechanical and electrical stimulation, which can be used to mimic the physical microenvironment of muscle cells, in order to promote their differentiation and maturation. I want to emphasize that achieving good muscle differentiation is a critical step. However, it is not enough to only achieve differentiation, as the maturation process of the muscle tissue is equally important. Maturation plays a crucial role in creating the natural texture of the muscle tissue. This is achieved by creating thick, aligned, and elongated muscle fibers that give the tissue its characteristic texture. Furthermore, the maturation process of the muscle tissue also leads to increased production of proteins that contribute to its nutritional value.

Orit:

So if we understand well, to differentiate the cells we need some goodies. However, you must also train muscle cells. Is it accurate Eilam? Could you please explain a little more about the mechanical and electrical stimulation you mentioned?

Eilam:

Sure, mechanical stimulation, for example, involves subjecting the tissue to physical forces, such as stretching. If I were to close my eyes and imagine myself as a happy cow walking peacefully in a meadow, my muscles would cyclically stretch and relax during movement. This biomechanical process actually causes various signals that promote the differentiation and maturation processes, and it helps to maintain and build the muscles. If we consider the embryonic development process, we can observe that the growth of the skeleton is faster than that of the soft tissues, leading to a consistent stretching of the muscle tissue. This stretching plays an important role in promoting the differentiation and maturation processes of muscle cells, as well as shaping the overall structure of the muscle tissue.

Moving on to electrical stimulation, which is actually exposure of the tissue to electrical pulses that cause it to contract cyclically. This method is based on the physiology of muscle activity, which is controlled through the nervous system by electrical pulses. As many of us know, if we want to increase muscle mass, we need to go to the gym. Electrical stimulation works in the same way and promotes differentiation, maturation, and growth. So, just like going to the gym, using electrical stimulation can help us produce cultured meat with larger, more mature muscle fibers and a more natural texture.

Orit:

How do you know whether you’ve succeeded in producing meat, muscle, or fat cells that are on par with native ones? What are the quality expectations? Dorit and Eilam and Nico

Eilam:

The process of differentiation, while it might sound complicated, is quite simple to understand. Let me explain it in simpler terms. When muscle cells are in their early stages of development, they are small, round, and individual precursor cells. However, during the differentiation process, these cells elongate and fuse together to form long and aligned multinucleated muscle fibers. We can observe this process using a microscope and evaluate it qualitatively or quantitatively. The better the differentiation process, the more muscle fibers we can see, which will be denser, more aligned, longer, and thicker. Moreover, the analysis of cells under a microscope can be significantly enhanced by using antibodies and various dyes that enable us to label different components of the cells, such as nuclei and various skeletal and muscle-specific proteins. This labeling allows us to visualize and distinguish different structures and proteins within the cells, providing us with a more comprehensive understanding of the cells’ characteristics during the differentiation.

In addition, during the differentiation into muscle cells, there are significant changes that occur in the cells at the molecular levels. These changes include increased expression of certain genes, and increased production of certain proteins, which can be examined and evaluated using various genetic and protein analysis methods.

Dorit:

The first step towards defining a desirable result is to induce the differentiation in tissue culture conditions and staining of the cultures with reagents that are specific to the differentiation process we induce- in adipo-differentiation we want to stain the fat inside the cells. In this process we compare different protocols according to the intensity of the staining. In addition, we test the protocols’ success by seeking specific markers that are present in the natural process of cell differentiation.

Because the fat contributes to the flavor and texture of the tissue/product, we would also like to reach a specific result in those parameters, so it is very important to perform taste and smell tests after the differentiation process is done, or even in intermediate time points during the process, so we can compare the taste of the native fat tissue to the cultured one. In parallel we perform lipid profiling of our differentiated samples and from that we learn what the cells do to the substrates we provide and how each composition affects the flavor, smell, and texture.

Orit:

Ok so this was about the cells but when it comes to our plate, how can you be sure that you have a product that reach the perfect smell, taste and texture?

Eilam:

The ultimate goal of developing cultured meat is to achieve a product that has the desired sensory attributes. Tasting panels are commonly used to assess those, in addition to their evaluation using advanced measuring equipment, such as electronic nose and electronic tongue, and texture analysis instruments.

Orit:

And what about the texture?

Eilam:

Texture analysis is a way to measure how a food product feels in our mouths. We can simulate actions like biting, tearing, or cutting and measure the properties that define the tested product’s behavior, and the goal in this aspect, is to make the product have the same texture as natural meat so that when people eat it, it will feel the same.

Nico:

Development of the texture of the final product – The goal is clear, to achieve the exact texture that one would feel if they were eating fish, for example, or a ribeye steak.

We can also monitor the nutrient composition. As the cells grow and differentiate into muscle and fat tissue, it’s important to regularly analyze the nutrient composition of the tissue. This will allow us to ensure that the levels of key nutrients such as protein, fat, and micronutrients are similar to those found in traditional meat.

We can also consider adding nutrients. If necessary, we can add specific nutrients to the growth media to ensure that the final product has a similar nutritional profile to traditional meat.

And finally we are conducting taste and sensory tests. In addition to monitoring the nutrient composition of the final product, it’s important to conduct taste and sensory tests to ensure that the cultivated protein has similar sensory qualities to traditional meat. This will help to ensure that the product is accepted by consumers and can be used as a viable alternative to traditional meat

Orit:

How do you make a product now that you have differentiated cells, such as fat or muscle cells?

Eilam:

To answer your question, there are many ways to generate a product with differentiated fat and muscle cells. One way is to incorporate the cells into plant-based products. By doing so, we can create products that are much more similar to natural meat compared to meat substitutes that exist today, in terms of sensory aspects such as texture, taste, aroma, and appearance. Additionally, with the help of cell culture and 3D printing technologies in our case, we can create products such as carpaccio, where a thin mosaic of muscle and fat cells are connected together in the right arrangement, or even a whole cut of meat by imitating the arrangement of muscle cells and fat cells in cuts like sirloin, fillet, or entrecote. I believe that in the near future, these products will be identical to the meat we currently buy at the butcher shop, except for the fact that they were grown in a laboratory.

Dorit:

When it comes to fat there are several ways to generate a product from the cells after they differentiate. One of them is to use the cells as a fatty biomass in processed products such as vegan patties that are supplemented with cultured fat for added flavor, plant-based sausages, and burgers. Another way is to encapsulate the cells in a 3-dimensional scaffold material and combine muscle differentiated cells to produce a “whole cut” product. A third option is to use fat as an independent product like tail fat after the cells are cultured to form a stand-alone tissue in a specific process. This product can be used for barbeque and anything that requires fat.

Nico:

Once you have the cells and the production process optimized, you can begin to formulate the product. This may involve combining the cells with other ingredients, such as plant-based products to give the final product a mouthfeel and flavor identical to the original product. But at the end we won’t need to mix our cells with different other ingredients, we will have a 100% cultivated protein product.

Orit:

Thank you, Dorit, Eilam and Nico

I hope you now have a clear understanding of this subject and how we can create differentiated cells to make cultured protein from immortalized cells developing in big quantities! Since there are no other questions from the audience, we will wrap it up. I sincerely hope you appreciated the scientific series on cultivated protein, as I did. So keep an eye on our social media sites for updates on upcoming events.

Thank you all for listening. Aurevoir

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