Fish protein concentrate is produced by processing fish to remove moisture and lipids, concentrating the protein content. There are three main types defined by their protein, moisture, and fat contents. Type A has the lowest fat level below 1% and is produced through solvent extraction. Type B and C have higher fat limits and can be produced through non-defatted processing. Functional properties like solubility and texture need improvement for use as a food additive. FPC provides a nutritious protein supplement but its acceptance has been limited by flavors and properties. It differs from fish meal which is used for animal feed due to potential safety issues for human consumption.

1. Fish protein concentrate
Fish protein concentrate is any stable fish preparation, intended for
human consumption, in which the protein is more concentrated than in
the original fish.
The idea of a fish protein concentrate (FPC) is that a stable fish material
may be produced in which the protein is more concentrated than in
original fish and which is intended for human consumption.
The idea of producing a fish protein concentrate is by no means new. The
Norwegians exhibited biscuits containing fish flour at an international
exhibition in 1876.
However, it is only in the last twenty-five years that extensive endeavours
have been made to produce fish protein concentrate, and only in the last
few years that most of the technical problems of making FPC on a large
scale have been solved.
The product was considered a panacea to fight protein-malnutrition

2. What are the principal types of FPC?
The Food and Agriculture Organization of the United Nations defines three
types:
Type A Type B Type C
Protein (N X 6.25) (min) 67.5% 65% 60%
Moisture (max) 10% 10% 10%
Fat content (max) 0.75% 3% 10%
Chloride (max) 1.5% 1.5% 2%
Silica (max) 0.5% 0.5% 0.5%

3. The fat content is important as it is the fat which tends to produce strong
flavours, particularly if it is oxidized.
To make a stable product, not only moisture but lipid content also should
be reduced appropriately. Simply cooking and pressing of a fish do not give
a product with sufficiently low lipid content.
Odours and taste: Type A should have no more than a faint odour and taste
when wetted with boiling water in a closed container
No specifications can be made for Type B and C since they will show a
wide range of odours and flavours.
Bacteriology: All types should be free from pathogenic anaerobes,
Enterococci, Salmonella/Shigella, Coagulase-positive Staphylococci and
Clostridia and have a total bacterial plate count at 98.60 F of not more than
10,000 per gram

4. Different approaches to make a stable fish product may be divided
into three main groups:
 Microbiological methods: Ground fish is mixed with microorganisms
which in turn hydrolyse proteins to water soluble peptides, which are
separated from oil phase through centrifugation and dried
 Precipitation of solubilized proteins through adjustment of pH:
Proteins are first solubilized by adjusting pH of the dispersing
medium to alkaline side and then the solubilized proteins are
precipitated through the control of pH to a lower value of about 5
 Solvent extraction methods: In a solvent extraction method, ground
fish is subjected to extraction with a solvent which removes both
moisture and lipids.
The solvent extraction method received the widest attention
Solvent extraction and removal of lipids make the product practically
free of fish–odours and the product is expected to have universal
appeal and may be incorporated in different traditional and non-
traditional preparations

5. Production of FPC type A
Unless white fish are used as the raw material, it is practically impossible
to reduce oil content below 1% without some kind of extraction by solvent.
Isopropyl and ethyl alcohols are the extractants most commonly used as
solvents to remove much of the fat, water and fishy tasting components.
Typical of the processes which were developed is the following sequence
of operations.
Fresh whole fish are rinsed with fresh water soon after landing, weighed
and fed to a mincer by a conveyor

6. First extraction: - The minced fish are fed to an extractor which is an
unheated vessel in which the mince is agitated for about 50 minutes with
the solvent mixture.
Centrifugation: - The slurry is separated into a solid and a liquid.
The solid cake is conveyed to the second extractor and the liquid to a still
for recovery of the solvent.
Second extraction: - The cake is agitated with solvent mixture for about
90 minutes at a temperature of 75oc.
Centrifugation: - The slurry is separated. The solid is sent to the third
extractor and the liquid to the first extractor for the next batch of raw
material.
Third extraction: - The cake is agitated for a further 70 minutes at 750 c
with fresh solvent. At the end of this stage the fat content of the dry matter
is reduced to about 0.3%

7. Centrifugation: - The slurry is again centrifuged and the wet cake washed
with pure solvent. The liquid is used in the second extractor for the next
batch.
Solvent removal: - The wet cake is heated in a rotary vacuum dryer to
evaporate the solvent.The vapours are drawn off, condensed and used
again.
Grinding and packaging: - The dried material can be left as a mince or
ground to any desired particle size.
The solvent and the solid fish protein material move through the
extractors in opposite directions.
The solvent becoming more contaminated with water and fat as it moves
from third extractor to the first extractor.
While the FPC loses fat and water as it moves the other way.

8. The fat can be recovered from the solvent and solvent can be used
again.
Solvent costs are high so that efficient solvent recovery is very
important
The extracted fat is normally much darker than that extracted by
pressing because solvent extraction removes more of the fat including
oxidized products and phospholipids.
The market value of this fat is likely to be lower than that of normaly
produced fish oil.

9. FPC type B production
Since type B FPC has no restrictions as to its odour and flavour any
process which produces a stable protein concentrate can be considered
and solvent extractions is not necessary because of the higher oil
content.
It can be produced from any kind of fish and its manufacturing process is
much less complex and less expensive.
FPC type B and C is essentially a non-defatted and non-deodorised
cooked hot air dried fish mince. It is also described as fish flour for use
as food, as distinct from fish meal which is used as animal feed

10. Production of FPC by enzyme hydrolysis
An enzymitically produced FPC that is bland in flavour and has good
functional properties has been produced using papain, pancreatin,
bromelin or ficin.
The process consists of hydrolyzing the fish protein and complexing it
with phosphate.
The protein-phosphate complex is precipitated at a pH of 2.5 to 3.5 and
the precipitate is centrifuged, washed and extracted with a polar
solvent to remove it from the lipids.
The precipitated complex is neutralized with a base and 10-20%
carbohydrates are added. It is then dried by spray or freeze drying.

11. Functional properties of FPC
The term “functional properties” is used to describe those physical and
chemical characteristics of a food which contribute to their performance
during manufacture, processing, storage and consumption except its
nutritional ones.
Attributes such as colour, flavour, solubility, mettability, foaming
behaviour, and inertness as well as rheological properties of the solution
and gels form a profile of properties which contribute to the acceptance of
the product.
The failure of FPC to be accepted as a food additive is attributed partly
due to its poor functional properties.
Unmodified FPC has an extremely low water affinity and imparts a gritty,
powdery texture to foods

12. Attempts were made to improve the functionality of FPC by a variety of
methods including gentle processing conditions and hydrolytic
modification by chemical and enzymic process.
Alkali treatment show improved melting, swelling and foaming
properties. The use of enzymes (trypsin, bacterial proteases) gives
excessive hydrolysis, leading to increased solubility but no
improvement in functional properties.
In the manufacture of FPC type B, concentrated fish solubles are added
back to the press cake before entering the drier.
The added salts, amino acids and other solutes added back to the
press cake lower the water activity of the product.
FPC is not intended to be used as a complete diet, rather, its use as a
high quality protein supplement.

13. It has an excellent amino acid balance and is particularly effective as a
supplement to cereals, which are low in lysine.
Residual ‘fishy’ flavour levels and its poor functionalities limit its
proportion in foods to around 10%depending on the avality of the
product.
The hope that FPC would be the solution to the nutritional problems of
the world has largely disappeared with the lack of acceptance and the
failure of most of the commercial scale ventures.
Recent research has been towards improving the functional properties
of fish protein concentrates with the aim of overcoming the acceptance
difficulty.

14. How does FPC differ from fish meal?
Fish meal as produced throughout the world is a very cheap potential
FPC, but it is not intended for human consumption; it is used for
making pig and poultry feeds for farming. Ordinary fish meal is
unsuitable for human consumption for three main reasons:
1. It is not normally made under sufficiently hygienic conditions to rule
out the risk of occasional contamination by disease-causing
bacteria.
2. It usually contains rancid fat which destroys certain vitamins and
may lower the nutritive value of the protein; a fish meal diet might
precipitate vitamin deficiency in poorly nourished people. Moreover
the flavour of the rancid fat is unacceptable in many societies,
though not in all.
3. There is a slight risk that the rancid fat may have a cumulative toxic
effect if consumed over a long period.
The first of these reasons is the most important; thus fish meal made
under hygienic conditions is called FPC type C.