SCP

The simplest application is to ethylene. There are only two elements and they are identical, so, completing the analogy with Huckel theory, let us define their energies ot -. The SCP matrix is... 

The principal interest in photosynthetic bacteria for thek appHcabiUty to SCP production (Table 1) has been in Japan, where Jiodobacter capsulatus has been used to treat industrial wastes in sewage ponds (40,41). The product has been evaluated as a protein supplement in laying hen rations for egg production with acceptable results (40). 

Large-scale SCP production processes for growing yeasts of the genus Candida from hydrocarbon substrates were developed by British Petroleum Co., Ltd. and Kanegafuchi Chemical Industry, Ltd. of Japan (57). However, the 100,000-t/yr capacity plants based on these processes, and constmcted in Sardinia and Italy, were abandoned because of regulatory agency questions regarding residual hydrocarbon contents of the products (2,3). 

Table 5 presents typical operating conditions and cell production values for commercial-scale yeast-based SCP processes including (63) Saccharomjces cerevisae ie, primary yeast from molasses Candida utilis ie, Torula yeast, from papermiU. wastes, glucose, or sucrose and Klujveromjces marxianus var fragilis ie, fragihs yeast, from cheese whey or cheese whey permeate. AH of these products have been cleared for food use in the United States by the Food and Dmg Administration (77). 

Table 5. SCP Production Processes Based on Nonphotosynthetic Microorganisms...

Other mold-based SCP processes that have been iavestigated iaclude utilization of sulfite waste Hquor by I aecilomyces varioti conversion of carob bean waste yg Jispergillus niger com- and pea-processiag wastes by Giotrichium sp. and coffee-processiag wastes by Trichoderma har anum (62). However, none of these processes is practiced commercially. 

Most of the bacteria, yeasts, molds, and higher fungi of interest for SCP production are deficient in methionine and must be supplemented with this amino acid to be suitable for animal feeding or human food appHcations. Also, lysine—arginine ratios should be adjusted in poultry rations in which yeast SCP is used (62). Human feeding studies have shown that only limited quantities of yeast such as Candida utilis can be added to food products without adverse effects on flavor (63). 

Nucleic acid contents of SCP products, which range up to 16% in bacteria and 6—11% in yeasts, must be reduced by processing so that intakes are less than 2 g/d to prevent kidney stone formation or gout. Adverse skin and gastrointestinal reactions have also been encountered as a result of human consumption of some SCP products (87). 

Future Uses. The most recent uses for methanol can be found in the agricultural sector. Test studies are being carried out where methanol is sprayed directly onto crops to improve plant growth. Methanol can be used as a carbon source for the production of single-cell protein (SCP) for use as an animal feed supplement. The process has been commercially demonstrated by ICl at their BiUingham, U.K., faciUty. However, the production of SCP is not commercially practical at this time, in comparison to more conventional protein sources. 

Normal paraffins in this range are important intermediates for alkylating benzene for synthetic detergents production (Chapter 10). They are also good feedstocks for single-cell protein (SCP). 

FERMENTATION USING n-PARAEEINS (Single Cell Protein SCP)... 

Single cell protein, normally called simply SCP, is the term used to describe microbial cells, or proteins from them, which are used as food (food for humans) or feed (food for farm animals or fish). Although the term micro-organisms covers viruses, bacteria, fungi, algae and protozoa, viruses and protozoa are not considered suitable for SCP production. 

The term SCP is not exactly appropriate, as some filamentous organisms are used as SCP and these organisms are multicellular not unicellular. 

What are they like to eat Humans are particular about the organoleptic properties of their food. Microbial cells may have little taste or smell, or even smell or taste unpleasantly to some people. The texture may not be the same as in conventional foods, particularly with unicellular organisms. These draw-backs can be overcome by adding a proportion of SCP to manufactured foods. However, even when SCP is incorporated into manufactured foods it may not have suitable characteristics such as stability, ability to bind water or fats, or ability to form gels, emulsions or foams. SCP for feed does not have to meet such strict requirements. 

Suggest ways of overcoming or bypassing the following disadvantages of SCP as food. 

We have seen that only certain micro-organisms that conform to nutritional and safety requirements are suitable for food or feed, and that food has more strict requirements than feed. In addition, for use as food, SCP should have a reduced nudeic add content and should be palatable. Most often this means that its use is limited to processed foods, in which food technologists can produce acceptable tastes, smells and textures. 

---