Introduction

Single Cell Protein (SCP) refers to protein-rich biomass produced by single-celled organisms like bacteria, yeasts, fungi, and algae. These microorganisms are cultivated on various substrates and processed into nutrient-rich protein supplements suitable for human and animal consumption.

Unlike conventional protein sources such as meat, soy, or fish, SCP can be produced rapidly, on a large scale, and from inexpensive raw materials like agricultural waste, hydrocarbons, and industrial by-products. This makes it a sustainable solution to global protein deficiency, malnutrition, and food insecurity.

SCP is easily digestible, has a balanced amino acid profile, and can serve as an alternative to conventional agriculture, which is land and resource intensive.

History of Single Cell Protein

During World War I, yeast was used in Germany as a substitute for half of its imported protein.
The first commercial SCP product, Pruten, was introduced as an animal feed additive.
The term Single Cell Protein (SCP) was coined by Carroll L. Wilson of MIT in 1966.
In 1967, during the First World Conference on Single Cell Proteins, the term was officially recognized to describe microbial proteins.

Microorganisms Used in SCP Production

A particular microbe, such as yeast or bacteria, is used as a strain to cultivate single cell protein.
Single-cell proteins are made by a wide range of microorganisms, including bacteria, actinomycetes, yeasts, molds, and some protists.
These microbes have traits such as the high concentration of protein and other nutrients they produce, as well as the fact that they have no pathogenic impact on the human body. Have a pleasant taste, are easily digestible and absorbable, need basic culture conditions, and grow quickly.

Fungi

Rhizopus cyclopean
Aspergillus fumigatus
Aspergillus niger

Yeasts

Saccharomyces cerevisiae (baker’s yeast)
Candida utilis
Candida tropicalis

Algae

Spirulina
Chlorella pyrenoidosa
Chondrus crispus

Bacteria

Bacillus megaterium
Pseudomonas fluorescens
Lactobacillus

These organisms are preferred because they are:

Non-pathogenic
Rich in proteins, vitamins, and essential amino acids
Easily digestible
Grown under simple culture conditions

Raw Materials for SCP Production

The basic components needed to create single-cell protein are very diverse; algae only requires carbon dioxide and sunshine, but bacteria, yeast, and For survival, mold needs hydrocarbons, ethanol, carbohydrates, and other substances.
A source of energy and a source of carbon are necessary to create single cell protein.
In addition to the nitrogen sources (such as ammonium salts or nitrates), the raw materials also need inorganic components such calcium, phosphorus, iron, magnesium, etc.
Raw materials include agricultural waste, wastewater (such as straw, bagasse, sugar beet bagasse, sawdust, and other cellulose-containing wastes), and the wastewater generated during the processing of agricultural and forestry products.
The fermentation industry produces industrial waste and wastewater, including sulfite pulp waste liquid and food, sugar-containing organic wastewater.
Petroleum, natural gas, and similar commodities like crude oil, diesel, methane, ethanol, etc.

Method of Single Cell Protein Production

1. Selection of substrate and strain

The selected organisms are those that grow quickly, have a high protein content, and possess acceptable growth features.
The chosen microorganisms are cultured on substrates that supply them with the necessary nutrients for their development.

2. Fermentation

The cells are grown in large quantities using a fermenter, which is a particular piece of equipment for culturing plant or animal cells.
The chosen microbes are introduced into the fermenter after being cultivated in the appropriate media.
To encourage microbial growth and reproduction, the temperature, pH, and oxygen content of the fermenter are all closely regulated.

3. Harvesting

Following the fermentation process, it is necessary to separate the microbial cells from the growth medium.
The method of harvesting varies based on the particular organism and manufacturing configuration.
The difficulty is in efficiently isolating the cells from the environment without causing excessive protein loss.

4. Post-harvest handling

The harvested microbial cells are dried in order to keep them and minimize their volume for easier storage and transportation.
Air drying, spray drying, freeze drying, or other appropriate methods may be used to dry.

5. SCP processing for food

After the cells have been dried, they are given postharvest treatment to improve their nutritional value, taste, and texture by removing contaminants.
Grinding, sieving, and refining are examples of processing methods used to create a higher-quality protein product.
Enhancing the overall quality of the SCP may require further actions, such as fortification with vital nutrients or flavor enhancers.

Factors Affecting Single Cell Protein Production

1. Temperature

There are several ways in which temperature affects the synthesis of single-cell protein.
The best temperature for producing SCP by submerged fermentation
The development of microbes can be influenced by temperature.
The pace of the fermentation reaction increases with temperature in the ideal range, along with the rate of growth and metabolism.
The fermentation rate decreases and the microbial activity is swiftly inactivated as the temperature climbs over the ideal range.
For this reason, maintaining the ideal temperature is essential for a healthy fermentation process.

2. pH

The fermentation rate, enzymatic activity, and behavior of microorganisms can all be impacted by pH.
The pH ranges according to the kind of substrate, media, and bacteria.
The starting pH of the medium is typically set to 7. 27. 3 in defined media, whereas it must be neutral or somewhat acidic in molasses.
The pH of the medium is adjusted using HCl, NaOH, and H2SO4.
Furthermore, the rate at which nutrients break down in the medium will be influenced by the pH. As a result, the fermentation broth’s pH should be regulated.

3. Oxygen Concentration in Solution

Oxygen is necessary for aerobic fermentation because it is a crucial component of it.
The oxygen needs of a fermentation process of single-cell protein are met by aeration and agitation.
For heat transfer, sufficient mixing, and mass transfer, agitation is crucial.
Maintaining a homogeneous culture requires continuous mixing through aeration and agitation.
For this reason, the fermentation mixture needs to have a lot of oxygen added constantly, and stirring can improve the oxygen’s solubility in the mixture.
The concentration of dissolved oxygen rose as the agitation speed rose.

4. Concentration of nutrients

The growth will be directly impacted by the amounts of different nutrients, particularly the ratio of carbon to nitrogen, inorganic salts, and vitamins, in the fermentation medium of the synthesis of single-cell proteins and bacteria.

Advantages of Single Cell Protein

Microorganisms multiply quickly and proliferate, enabling them to generate a lot of biomass in a short amount of time.

Genetic Manipulation: Microbes are simple to genetically alter, which allows for versatility in changing the amino acid makeup of proteins.
Using Waste Materials: A variety of raw ingredients, including waste items, can be used to make SCP, which reduces the environmental effect of pollution.
Climate Independence: The fact that SCP manufacture is not dependent on particular climatic conditions makes it more dependable in diverse locations.
Manufacturing significant amounts of biomass: SCP is obtained from lower organisms that generate large quantities of biomass.

Disadvantages of Single Cell Protein

Nucleic Acid Composition: The high concentration of nucleic acid in SCP may result in gastrointestinal issues in people.
Allergic Reactions: Some people with sensitive digestive systems may have allergic responses to the biomass.
Uric acid levels can rise in the bloodstream when there is a high concentration of nucleic acids.
Kidney Stones and Gout: Daily SCP intake might lead to the development of kidney stones and gout.

Applications of Single Cell Protein

Food and Supplement: SCP is a sustainable and alternate protein source for human diets and food.
Animal feed: SCP provides a wholesome and practical feed option for poultry, fisheries, and animal farms.
Pharmaceutical and Therapeutic Applications: SCP has the potential to help regulate stress, weight, obesity, cholesterol, and blood glucose levels.
Products for Skin and Hair Care: Due to its high protein content, SCP is a good option for use in skin and hair care products.

Conclusion

Single Cell Protein (SCP) is an innovative, sustainable, and eco-friendly alternative to traditional protein sources. With microorganisms like yeast, bacteria, fungi, and algae, SCP can be produced from low-cost substrates and waste materials, making it vital for addressing global protein shortages.

Although challenges such as high nucleic acid content and allergenicity exist, biotechnology is continuously improving SCP safety and quality. Its applications across food, feed, medicine, and cosmetics highlight its vast potential.

In a world facing population growth, climate change, and food insecurity, SCP could become a key player in sustainable nutrition and complement traditional protein sources.

FAQs on Single Cell Protein

Q1. What is Single Cell Protein (SCP)?
SCP is microbial protein biomass produced from algae, yeast, fungi, or bacteria, used as an alternative protein source for humans and animals.
Q2. Which microorganisms are used in SCP production?
Examples include Saccharomyces cerevisiae (yeast), Spirulina (algae), Bacillus (bacteria), and Aspergillus (fungi).
Q3. What are the advantages of SCP?
Fast production, waste utilization, eco-friendliness, and independence from farmland and climate.
Q4. What are the disadvantages of SCP?
High nucleic acid content may cause health issues, and some people may have allergies.
Q5. What are the applications of SCP?
Used in food supplements, animal feed, pharmaceuticals, and cosmetics.
Q6. Is SCP safe for human consumption?
Yes, but only after proper processing to remove excess nucleic acids and toxins.

Single Cell Protein (SCP): Sources, Production, Advantages, Disadvantages & Applications