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Sunday, June 24, 2012

SIngle Cell Protien (SCP):Process, Applications & Benefits


Single-cell protein (SCP) are dried microbial cells or total protein extracted from pure or mixed cultures of microbes  such as algae, yeasts, fungi or bacteria (grown on agricultural wastes) used as a substitute for protein-rich foods, in human and as for animal feeds.


Single cell proteins have application in animal nutrition as: Fattening calves, poultry, pigs and fish breeding.

In the foodstuffs area as: aroma carriers, vitamin carrier, emulsifying aids and to improve the nutritive value of baked products, in soups, in ready-to-serve meals, in diet recipes and

In the technical field as: paper processing, leather processing and as foam stabilizers.

Medicinal Uses of Spirulina

•Strengthen and improve immune system 
•Phycocyanins build blood cells
•Increase antiviral activity
•Exhibits anti cancer activity
• Studies showed that spirulina consumption of 4 weeks reduced serum cholestrol level in human beings by 4.5%(Henrikson 1994) and significantly reduced body weight by 1.4±0.4 kg after 4 weeks(Becker et al 1986)
• There is no changes in clinical parameters (Blood Pressure) or in biochemical variables (haematocrit, haemoglobin, blood cells, sedimentation rate) and absence of adverse effects.
• The reduction of cholesterol is partly due to high content of gamma linolenic acid in cyanobacteria(Henrikson 1994).

SCP spirulina 

Microbes as Single Cell Protein Source


Average composition of the main groups of micro-organisms (% dry weight)
Fungi
Algae
Yeasts
Bacteria
Protein
30-45
40-60
45-55
50-65
Fat
2-8
7-20
2-6
1.5-3.0
Ash
9-14
8-10
5-9.5
3-7
Nucleic Acids
7-10
3-8
6-12
8-12
Table: Miller et al (1976)


chlorella SCP




Microorganism
Substrate
Used as
Used commercially
Algae

Chlorella sp.
CO2 + sunlight
Feed
Yes (Japan and Taiwan)
Scenedesmus acutus
CO2 + sunlight
-

Spirulina maxima
CO2 + sunlight
Feed
Yes (Mexico)
Yeasts

Candida utilis (Torula Yeast)
1. Confectionery
-
Yes (U.K.), Symba process

2. Ethanol
Feed
Yes (USA)

3. Sulphite liquor
-
Yes (Europe, USA, Russia)
C. intermedia
Whey
-
Yes; Vienna process
C. krusei (+ Lactobacillus bulgarius)
Whey
-
Yes; Kiel process
C. lipolytica
n-alkanes (C10 - C23) + ammonia
-
Yes (Russia)
Kluyveromyces fragilis
Whey
Food
Yes (France); Le Bel process
Saccharomyces cerevisiae
Molasses
(Food)*
Yes
Fungi



Chaetomium cellulolyticum
Cellulosic wastes
-
Promising
Fusarium graminearum
Starch hydrolysate

Yes (U.K)
Paecilomyces varioti
Sulphite liquor
-
Yes (Finland); Pekilo process
Bacteria



Brevibacterium sp.
C1 - C4 hydrocarbons
-
Process developed
Methylophilus methylotrophus
Methanol
Feed
Yes (U.K.),

Single Cell Protein Production Process

Single cell Protein Production process follows these steps
  1. Microbial Screening
  2. Choice of Raw Materials
  3. Process Engineering and Process Optimization
  4. Technology Development
  5. Economic Consideration / Process Feasibility
  6. Safety Concerns
Microbial screening: 

Microbial Screening is the first step in Production process, suitable microbe which yields good amount of protein need to be selected. microbial strains are collected from various habitats like soil, water, air and or from other biological materials. Microbes are selected by various studies including mutagenisis and other genetic methods, some times wild types are also  used.

Choice of Raw Material :

This part is little cumbersome and one need to focus on the correct composition of carbon suppliment which yields higher biomass production in lesser time need to be analyzed. various carbon sources are like wood waste, straw, other food processing wastes are also can be tried to optimize higher biomass production.

Substrates for Single Cell Protien Production can be subdivided into three categories:

High energy sources (natural gas, n-alkanes, gas-oil, methanol, ethanol, acetic acid); 

Various wastes (molasses, sulfite waste liquor, milk, whey, fruit wastes); and

Renewable plant resources (sugar, starch, cellulose).

Process engineering:

The technical conditions of cultivation for the optimized strains are done and all metabolic pathways and cell structures will be determined.

algal culture for single cell protein
                       Algal Bioreactor

Technology Development:

Technology development is the next step where the adoption of the technical performance of the process in order to make the production ready for use on the large technical scale.

Economic factors:
Energy consumption, cost of production are the important factor while going for large scale production phase, this need to be thoroughly analyzed and an energy efficient process need to be developed or else it will end up with loss.

Safety demands & Environmental protection:

Since the SCP produced is for human consumption or for feeding animals safety of the product need to be tested. certain microbes produces toxic compounds which can have determinal effect on humans and also for the environment, so the whole process should be monitored properly.

Advantages of Single Cell Protein 
Advantages of using microbes for  Large scale production of Single cell proteins are
  1. Single cell protein high protein and low fat content.
  2. Single cell protiens are good source of vitamin.
  3. It can be produced through out the year.
  4. Generation time of microbes are less, ie, they multiply rapidly building up the biomass, more the biomass more the protein source.
  5. Protein content is very high in dried biomass upto 85%
  6. During the production of  SCP biomass, certain microbes produce usseful byproducts such as organic acids.
  7. Waste (wood waste, food processing waste, hydrocarbons, etc) can be used as a source for carbon for growing microbes there by having advantage of environmental clean up also.
  8. Doesn't require sophisticated lab setup for algae and certain other microbes.
  9. High efficiency substrate conversion. 
Disadvantages of Single Cell Protein


Even though it single cell proteins have the above mentioned advantages, it has some disadvantages also, the major problem associated with the use of single cell proteins are
  1. Many microbes produce various toxic compounds, so consumption of such toxic can have serious effect on health of humans (Food Grade SCP), or in animals (Feed).
  2. Single Cell Protein diet suppliments can pose allergic reaction.
  3. Consuming SCP, in-taking higher amount of Nucleic acids which can lead to gastrointestinal problems.
  4. Food grade SCP production are expensive due to the need to maintain high level sterility conditions in the production facility.
References:
Wikipedia
SCP, Shraddha Bhatt