Tímarit Verkfræðingafélags Íslands - 01.12.1967, Page 291

TlMARIT VFl 1967
289
5. Selection and definition of prototype pro-
cessing method. — We now come to a brief d,e-
scription of the prototype method that was finally
developed.
In summary, the process for the manufacture
of FPC from hake consists of the following steps:
the raw fish — frozen or iced and of food-grade
quality — is suitably comminuted and immedia-
tely mixed with isopropyl alcohol at ambient
temperature. Extraction of most of the water
and part of the fats takes place at this stage.
The slurry is then separated into liquid and sohds
by centrifuge or other suitable equipment and
the solids extracted again with isopropyl alcohol,
but this time at temperatures close to boiling
point of the alcohol. The extracted solids are
finahy desolventized under vacuum, then screened
and milled to the required particle size. The sol-
vent is recovered by distillation and deodoriza-
tion. Extraction is carried out batchwise or
continuously by co-current or counter-current
extraction. The process is carried out in stain-
less steel extraction vessels with sanitary fitt-
ings.
Process and Product Evaluation
We have, above, discussed the goals of the
Bureau program and the rationale for developing
an FPC manufacturing process. Some facts must
now be given concerning the approximate process
cost and the properties of FPC manufactured by
the selected method.
Capital Investment and Processing Costs
The following preliminary cost estimates are
quoted here to give an idea of the order of
magnitude of capital investment and processing
cost. The figures are based upon a 3-stage,
counter-current batch extraction, yielding FPC
at the rate of 15 percent by weight of the raw
material. The end-product contains 80—90 per-
cent protein, less than 0.5 percent total fats, less
than 10 percent moisture, and 5—10 percent
mineral matter. The total capital investment re-
quired for the construction of a plant capable
of processing about 50 tons of raw material per
24 hours by the above method is approximately
1 million dollars. Processing costs, excluding
harbor facilities, marketing, and profit, but in-
cluding 12-year amortization, labor, buildings,
power, maintenance, and a raw material cost of
1 cent per Ib. of raw fish, were calculated to
be about 14 cents per lb. of the finished FPC.
Properties of FPC
FPC was prepared according to the selected
method from red hake (Urophycis chuss) in a
model scale unit (small pilot plant) situated in
BeltsviUe, Maryland, and exhaustively examined.
Evaluation of this product included a deter-
mination of its physical, chemical, and sensory
properties, a determination of its protein quaUty
ond its microbiological safety, and an examina-
tion of its wholesomeness.
Physical Properties
The physical definition of the FPC test sample
included observations on the color, particle size
distribution and particle identification.
The color of the sample as determined by re-
flectance measurements was defined as off-white,
with a yellowish cast.
Chemical Properties
The proximate analyses of a representative
batch of FPC test sample before adjustment of
the fluorine content was as follows: protein:
81.4 percent; volatiles: 6.7 percent; ash: 13.5
percent: and total fat: 0.2 percent.
The amino acid composition of FPC was deter-
mined and found to be close to the amino acid
spectrum of the raw material.
The non-protein nitrogen content of the pro-
duct compared favorably with that in other
foods and consisted mainly of amino acids.
Residual fats and fat-like substances (Upids)
in FPC were studied by Dr. H. Olcott at the
University of Califomia in particular as to their
possible role in flavor reversion or in the deve-
lopment of rancidity. Tests showed that the lipids
underwent no oxidative changes even after 3
months’ storage of the extracts.
No sand was detected in the sample.
The FPC test product had no fish odor, prob-
ably owing to the very smaU levels of volatile
amines observed by Dr. Emily Wick at the
Massachusetts Institute of Technology.
Sensory Properties
FPC was analyzed by the Flavor Profile Met-
hod immediately after production and after 9
months’ storage at room temperature. Regard-
less of the age of the sample, the panel described
the FPC as typical of a processed dry protein
product with no evidence at either time of fishy
taste or odor.