THE COMPARATIVE TECHNO-ECONOPIC STUDY OF CONVENTIONAL AND NONCON- VENlONAL TECHNOLOGIES FOR FOOD PRODUCTION
3. Obtaining Protein Products by means of Non-traditional Technologies
All the non-traditional methods of obtaining proteic substrates from veget- able raw materials can be divided into the following categories (Fig. 4):
1. Protein extraction from raw materials.
2. Protein biosynthesis by yeasts and obtaining from them protein isolates and amino acids.
3. Enrichment of wastes (used as a feed) by means of microbial protein.
4. Protein biosynthesis by using h g h e r fungi.
5. Protein biosynthesis by means of microscopic fungi.
6. Protein biosynthesis by using bacteria.
7 . Protein biosynthesis by means of symbiotic-methods using various micro- organisms.
8. SCP production from algae.
The extraction of protein substances from vegetable raw materials is used extensively. A t presently, this method is the main non-traditional method of obtaining food protein. Mamly these proteins are applied in feed. Wastes of vegetable food protein production are used in cattle-breeding or are not used at all. Such a technological approach is no longer acceptable. It is more advisable t o use solid and liquid wastes a s a substrate for microbial protein production.
Yeasts a r e t h e most productive micro-organisms for the protein biosyn- thesis. The grown biomass is used as a feed. Many authors propose protein iso- lates, extracted from them, in feed.
Amino-acids a r e extracted from yeast autolysates and are offered for food.
The positive character of yeast production is their short cultivation cycle with 6
-
10 hours duration, h g h productivity of protein, 50-60%, and low prices. It does not require expensive equipment nor completely sterile conchtions. The nega- tive character of t h s process is a hlgh content of RNA, that causes their Limited application as well a s the necessity of preliminary polysaccharide hydrolysis.Polysaccharides occur in large amounts in agricultural wastes.
Higher fungi are excellent resources of non-traditional food protein, but their cultivation is possible only on a limited number of substrates. Their appli- cation is limited by h q h costs and specificities in relation to organoleptic and rheological properties.
Undoubtedly the production of h g h e r fungi is a possibility, but its volume will have little effect on protein supplies for the population.
Microscopic fungi have some advantages in comparison with other micro- organisms. Their main advantage is their ability to synthesize enzymes, which hydrolyse hemicellulose, cellulose and partially lignin.
Therefore, with the help of specially selected microscopic fungi we can syn- thesize protein from cellulose and lignin containing wastes without their prelim- inary hydrolysis. Ths ability of microscopic fungi gives the possibility for the extensive annual recycling of the large plant resources of our planet.
The potential of this raw material makes us think that SCP obtained from microscopic fungi will play the main role in the solution of the protein problem in the future. The ability of microscopic fungi to synthesize no more than 1.5-3%
of RNA, and to produce wholesome protein and cellulosic enzymes strengthen the possibilities of this trend. The above mentioned aSility of the microscopic fungi illustrates their unlimited application in c a t t l e - b r e e d a not only as pro- tein addition, but also as an enzyme preparation whch helps to digest rough feed.
The need for complete sterility during production and the more prolonged cultivation ( 2
-
3 days), we-can consider as negative characteristics of micros- copic fungi.Taklng into account the positive and negative peculiarities of various micro-organisms their combined cultivation (so- called symbobiotic method) is carried out. We consider this is potentially the most effective way as it gives the best SCP synthesis.
Enrichment of feed directly with microbial protein is another promising trend. The cultivation of yeast, microscopic fungi, and bacteria is carried on simultaneously or consecutively. m s trend cannot ensure very good production or a well controlled biosynthesis, but it is easily feasible and doesn't require large expenditures and complex equipment. Nowadays, one widley applied cul- tivation is that of Spirulina as well as the cultivation of Chlorella and blue green algae. For this we have to solve several problems: cell wall splittmg, protein extraction, and their purUlcation from harmfull compounds, etc.
Every separate region should carefully weigh a number of factors such as:
the state of cattle-breeding, t e c h c a l potential, raw material base, etc., whd.e trying to obtain proteins by non-traditional technology. That is why every part of the country needs elaborate models which consider the above-mentioned fac- tors.
In this respect the optimal variants are most complex as each factor should reflect the latest data and the advantages and drawbacks of the given factor.
'The picture becomes still more complex if we consider these factors isolated from one another. That's why when elaborating optimal regional models we can have d s e r e n t versions.
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Fig.1 Main facton determining selection and classification of raw material for protein production.
7 '
Raw Material
I
1
ProteinI
Extraction W~th High Protein Content
Protein Microbial
pzqpq ,GI
With Low Protein Content
Fig.3 PFC-protein-enzyme concentrate.
Protein Extraction from Vegetable
Raw Material Wastes
I
Protein Biosynthesis by Y cans.
T
Protein Biosynthesis C Solid Phased
B
by High Fungi Fermentation
b
Protein Biosynthesis by Microscopic Fungi
I
Protein Biosynthesis Fernentation by
by Bacteria Submerged Grad
A A
Protein Biosynthetis by Symba--Method by Means of Microorganisms
Enrichment of Feed with Microbial Protein
SCP Production from Algae
Fig.4 Nontraditional technologies of protein obtaining from vegetable and raw material.
COMPARATIVE BIOENERGETIC EFFICIENCY OF CATTLE PRODUCTION AND