scp

• Single-cell protein (SCP)


  Sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria (grown on agricultural wastes) used as a substitute for protein-rich foods, in human and animal feeds
• Earliest record of the use of yeast from Persia (modern Iran)

  7000 years ago
• Earliest examples of leavened bread from Egypt

  6000 years ago
• Yeasts have been used in bread and beverage production


  2500 BC
• Processes for preparing highly concentrated forms of yeast were established


  1781
• Research on Single Cell Protein Technology started

  1 century ago
• Single Cell Protein Technology proved to be more than useful as Germany used it to replace more than half of its imported protein sources by yeast


  World War I
• Sak in Denmark and Hayduck in Germany invented a method named "Zulaufverfahren"


  1919
• Interest of Germany revived in fodder yeast by the 'Heeresverwaltung'


  1936
• The Food and Agriculture Organization of the United Nations (FAO) emphasized on hunger and malnutrition problems of the world, introducing the concept of protein gap


  1960
• Almost quarter of a million tons of food yeast were being produced in different parts of the world


  Mid 1960s
• "Proteins-from-oil process"


  A technology for producing single-cell protein by yeast fed by waxy n-paraffins, a product produced by oil refineries
• A small pilot plant started operations at BP's Lavera Oil Refinery in France

  1963
• The term SCP was coined by Carroll L. Wilson of MIT


  1966
• Champagnat was awarded the UNESCO Science Prize


  1976
• Single-cell proteins


  • Develop when microbes ferment waste materials (including wood, straw, cannery, and food-processing wastes, residues from alcohol production, hydrocarbons, or human and animal excreta)
• Dehydration


  Single-cell protein must be dehydrated to approximately 10% moisture content
• Acidification


  Single-cell protein must be acidified to aid in storage and prevent spoilage
• Microbes employed


  • Yeasts (Saccharomyces cerevisiae, Pichia pastoris, Candida utilis=Torulopsis and Geotrichum candidum (=Oidium lactis)), other fungi (Aspergillus oryzae, Fusarium venenatum, Sclerotium rolfsii, Polyporus and Trichoderma), bacteria (Rhodopseudomonas capsulata), and algae (Chlorella and Spirulina)
• Typical yields


  43 to 56%, with protein contents of 44% to 60%
• Fungus Scytalidium acidophilum


  • Grows at below pH 1, offering advantages of low-cost aseptic conditions, avoiding over 100-fold dilution of the acidic hydrolysates to pH values needed for other microbes, and after the biomass is harvested, the acids can be reused
• Amino acid profiles


  Some bacterial SCP have different from animal proteins
• Yeast and fungal proteins

  Tend to be deficient in methionine
• Ingestion of purine compounds

  Leads to increased plasma levels of uric acid, which can cause gout and kidney stones
• Nucleic acid removal


  Not necessary from animal feeds but is from human foods
• Temperature hold at 64 °C


  Inactivates fungal proteases and allows RNases to hydrolyse RNA with release of nucleotides from cell to culture broth
• Advantages of production


  • Microorganisms have a high rate of multiplication and rapid succession of generations, can be easily genetically modified for varying the amino acid composition, have a very high protein content, can utilize a broad spectrum of raw materials as carbon sources, strains with high yield and good composition can be selected or produce relatively easily, production occurs in continuous cultures and the quality is consistent, land requirements is low and is ecologically beneficial, have a high solar-energy-conversion efficiency per unit area, and algal culture can be done in space that is normally unused
• Drawbacks


  High concentration of nucleic acids which elevates serum uric acid levels and becomes cause of kidney stone formation, presence of cell wall which is non digestible, unacceptable color and flavors, cells of organisms must be killed before consumption, chance of skin reaction from taking foreign proteins and gastrointestinal reactions may occur resulting in nausea and vomiting, SCP obtained from algae is not suitable for human consumption because they are rich in chlorophyll, SCP from yeast and fungi has high nucleic acid content, SCP obtained from bacteria also has high nucleic acid content, high risk of contamination during the production process and cell recovery also causes many problems