What is Single Cell Protein?

Ever wonder what would happen if there wasn’t enough food for everyone to eat? How will we manage to live? What if there isn’t enough meat, chicken, or fish to survive on? What if the agricultural output is completely saturated?

Relax! None of this is happening, at least not right now. But if the food issues aren’t resolved, we might see something similar in the future. Given that we are fully aware of the global population expansion, which has tremendously inflated the demand for food supply. For this reason, around 1/4th of the total population suffers from hunger and malnutrition.

The convention food sources like agricultural output, poultry, fishery etc., are incapable of catering this high demand for food. As a result, there is a greater need than ever for alternative nutritional dietary supplements.

One such alternative is Single Cell Protein.

The single cell protein (SCP) is a dried cell mass of protein-rich microorganisms that is capable of curbing the need for proteins in the form of human food or animal feed. SCP is a term used to describe the edible proteins that are extracted from the pure microbial culture either in a crude or refined state.

Definition of SCP

We can define SCP as the nutrient-rich biomass derived from unicellular or multicellular organisms.

This content provides information about single-cell protein, its types, importance, production, advantages and disadvantages. You will also get various examples and the related images below. So let’s get started.

Why is Single Cell Protein Important?

Currently, the requirement for proteins or other nutrients is increasing daily. On the other hand, the nutritional value of the agricultural products is degrading due to problems like soil erosion, pollution and so forth.

In such a case, we just don’t need something to replace our conventional food, but it should also possess enough nutrient content. Different types of organisms produce different kinds of Single-cell proteins with varied nutritional indexes. Some may produce more protein, while others may produce some other nutrient in large amounts.

You can understand the importance of SCP as it contains a good amount of protein and other essential nutrients. When you compare the nutritional value of SCP to other foods, you’ll see that even a small amount equals the nutritional value of many foods.

History of Single Cell Protein

In the year 1781, Max Delbruck and his fellow mates started researching about SCP after finding out the high value of brewer’s yeast as animal feed. Later, during the second world war, this yeast-SCP was extensively employed as a food supplement in Germany to cater for the problem of food shortage.

In the 1960s, technology came into existence that could directly extract the protein component of yeast. They referred to this technology as “Protein from the oil process“.
Carroll L. Wilson of MIT was the who coined the term single cell protein or SCP in the year 1966.

Nutritional Composition of SCP

Types of Single Cell Protein

We can broadly classify the SCP into two categories: food grade and feed grade.

Food grade SCP: The SCP that is suitable for human consumption as if not have any toxic or allergic effects, then they are Food grade SCPs.
Feed grade SCP: The SCP is regarded as feed grade if they are not suitable for human food but are considerable for animals, then it is feed grade SCP.

Applications of Single Cell Protein

It is a source of instant energy supply.
Enhances the health of your skin and eyes.
It is the best protein supplement for kids suffering from malnutrition.
Can manage the problems related to deficiency of vitamins, minerals, and crude fibre in humans.
Uses of SCP in therapeutic and medicine
SCP can control the obesity level, thereby maintaining body weight. It also keeps the cholesterol and stress levels in check.
Uses of SCP in cosmetics
Actively used in hair products, bio-lipsticks, herbal creams etc.
Uses of SCP in poultry and cattle farming
Since it serves as a good source of protein, thus people highly prefer them for feeding their cattle, fish, birds etc.

Procedure of Single Cell Protein Production

The production procedure starts with choosing the right type of raw substrate for SCP.

Raw material/ Substrate for SCP

The nature of the raw material highly matters in the case of SCP production as it is the deciding factor for its final cost. This means that the costlier the raw substrate, the more expensive the SCP or its products will be.

Some commonly used raw materials are:

High Energy Sources. Examples: Methanol, ethanol, alkanes.
Waste Products. Example: Whey, bagasse, molasses, straw.
Wood. Examples: Lignin and cellulose.
Carbon Dioxide(Simplest carbon source)
Sewage waste. Examples: Animal, human and industrial.

The production steps include five major steps:

Step 1: Selection of Microorganisms

It is a very crucial step in SCP production. It decides the time required as well as the quality and quantity of the final yield. One should be careful while the selection process and thoroughly check if it generates any undesirable effects on the consumer.

The following are the characteristics that the microorganism must possess to produce SCP:

Step 2: Fermentation

You can carry out the fermentation procedure in large equipped vessels called fermenters. Fermenters are equipped with an aerator, pH meter, and thermostat to maintain the optimal growth condition. Mainly fed-batch culture is preferred for their cultivation.

Industries also prefer personalised trenches or ponds to carry out the fermentation process.

Step 3: Harvesting

After the complete development of microbial culture/colonies, they are harvested by the decantation method. The decantation process yields a bulk of microbial cells in the crude state.

Step 4: Post-Harvesting Treatment

After harvesting the crude microbial cell, the mass is subjected to several processes so as to remove the debris and purify the desired product.

The post-harvesting methods might include- separation, washing and then drying of the crude biomass.

Separation: This process helps to separate the cellular components from the liquid waste. For the SCPs from yeast and bacteria, the process of centrifugation, flocculation and flotation is used for cell recovery.
Whereas the filtration method is used for the fungi, especially the filamentous ones.
Washing: Here, the separated biomass is washed with plain water.
Drying: It is a very important process where all the excess water is removed from the cell mass. After final drying, the dried cells are obtained.

Step 5: Processing of SCP

Based on the nature of substrate material and desired food or feed, further processing is done before yielding the final formulation of the SCP product.

Cell wall degradation: Various organisms possess cell walls of different types. As per the respective cell wall composition, specific cell wall degenerating processes are used.
It leads to the bursting of the cell wall, thereby bringing out the inner components.

Nucleic acid removal: The SCP cells contain a very high amount of nucleic acids that may be harmful for consumption.

Single Cell Protein can be obtained from

Single-cell protein from algae

The algae are a famous SCP choice due to their high protein content, i.e., around 60-70%. Also, they are rich sources of the nutrients like omega-3 fatty acids, minerals, carotenoids, vitamins A, B, C and E. The nucleic acid content is not very high, reducing the processing step. For this reason, they are the most used form of SCPs.

A good example of this is spirulina coming from Arthrospira platensis and Arthrospira maxima. Nowadays, spirulina is in demand and available in various forms like capsules, pills, powder, smoothies, canned drinks, juices and so forth.

Single-cell Protein From Fungi

Certain fungi are also good sources of SCP, including Saccharomyces, Fusarium, and Torulopsis. Their protein content is 30-50%, slightly lower than algae’s. This SCP is rich in nutrients like B complexes, low-density cholesterols, and amino acids such as threonine and lysine. Their cell wall part is highly fibrous and thus used as a source of dietary fibre.

Single Cell Protein from Bacteria

A variety of bacteria present in the digestive tract helps in digestion. Similarly, the bacterial SCPs also contribute to the betterment of digestion. Along with that, it aids the formation of new good bacteria.
The protein obtained from bacterial SCP is around 50-80%, but they are the most complex SCPs for the industries.

Examples of Single Cell Proteins

Advantages of SCP

Their nutritional constitution is exactly the same that our body needs to remain healthy. It has lots of protein, a moderate amount of carbs and a very lower fat per cent.
In comparison, the quality and the quantity of the protein obtained in the form of SCP is better than higher plant and animals.
You can easily cultivate them by using a wide variety of raw materials starch-rich wastewater from food processing industries, straw molasses, animal manure and sewage. Because of this, its production cost becomes low.
Culturing and fermentation processes for SCP are very simple.
Due to the high growth rates of microbes, they can double their mass in less than 30 minutes. Thus, you can obtain a large yield in very less time.
It reduces the pressure on conventional sources like agriculture for food supply.
Since it can utilize industrial effluents, thus, also helps to minimize pollution.
You can produce them throughout the year since they do not require any special season to flourish.

Disadvantages of SCP

The quantity of nucleic acids in the SCP biomass is quite high. Humans have a certain limit for digesting nucleic acids; thus, excess consumption might be hazardous.
The chances of production of carcinogens and toxins along with the natural biomass are very common. This may lead to several health issues.
Sometimes, the SCP production is accompanied by hydrocarbons, mycotoxins, heavy metals etc., which are difficult.
The production of food grade SCP is more expensive than that of feed grade.
The process of digestion of the microbial cells in the human body is very slow. Therefore, the SCP consumer might suffer from indigestion or allegoric responses.

Frequently Asked Questions (FAQs)

Is Single cell protein safe?

The consumption of SCP in its raw or crude form might be harmful as it may contain several harmful toxins, carcinogens, allergens, or some indigestible fibres. Sometimes higher concentrations of any particular nutrient can be harmful too.

But that doesn’t make SCPs unsafe. Prior to utilization, all the necessary processing needs to be performed. After complete processing, SCPs can be a good source to replace conventional protein sources.

Is mushroom a Single cell protein?

Yes, they are one of the best and oldest sources of SCP. But not all the mushrooms can be used as SCP. Only limited species of mushrooms are edible, but that also need proper processing to become SCP.