Means of reducing the quantity of water required for the washing
unit operation in surimi processing were evaluated. The yield of flesh
mechanically dewatered with a screw press and the degree of reduction in
trimethylamine oxide (TMAO) content were used as indices of washing
efficiency. Variations in water:minced flesh ratio, multiple exchanges
and washing conditions near the mean isoelectric point of flesh proteins
were techniques evaluated to optimize the yield and quality of washed
minced flesh.
Single exchanges in potable water produced solids and protein
recoveries superior to those observed for multiple exchanges utilizing
the same total amount of water. A single exchange of a water:minced
flesh ratio of 3.0 produced the highest recoveries (73.32 and 74.07 % of
flesh solids and protein, respectively) with the composition
characteristics desired. Multiple potable water exchanges (water:minced
flesh ratio = 1.0/exchange) at equal total water volume produced desired
composition characteristics, but pressed flesh yield was reduced (65.9
and 68.5 % of flesh solids and protein, respectively). Washing
(water:minced flesh = 1.0) under acidic conditions near the isoelectric
point (pH 4.9-5.3) of the minced flesh protein followed by a potable
water wash (water:minced flesh = 1.0) produced recoveries (73.02 and 76.20 % of flesh solids and protein, respectively) superior or equal to
all of the wash regimes of equal total water volume. These recoveries
were observed even with considerable loss during screening between
exchanges and at a water usage 66 % of the single exchange (water:minced
flesh ratio = 3.0) of potable water.
The moisture content of pressed flesh was increased by both the
total potable water:minced flesh ratio and by the number of exchanges to
which minced flesh was exposed. Moisture contents mediated by the
number of exchanges were a function of water volume and exposure time.
Washing conducted in an acidic water:minced flesh mixture at pH 4.9-5.3
(near the mean isoelectric point of flesh proteins) produced pressed
flesh with a moisture content 10.09-15.09 percentage points lower than
minced flesh wash in an identical (total water:minced flesh ratio; means
of separation between exchanges) potable water regime.
Washing under acidic conditions produced the most efficient
reductions in TMA0 and lipid content (91.4 and 31.1 % of flesh TMA0 and
lipid, respectively). Superior reductions were accomplished through pH
conditions favoring the extraction of amines and by the greater
pressures produced during screw pressing by the altered physical
characteristics of the flesh. Pressing between multiple potable water
exchanges also showed better reductions than single exchanges involving
only one pressing operation.
"Folding test" evaluation of heat-set gels (kamaboko) produced from
a standard surimi formulation (containing 4 % each of the
cryoprotectants sucrose and sorbitol and 0.5 % condensed phosphate) with
the addition of 5 % each of potato starch and dried egg white revealed a
difference between potable water and acid-washed flesh. Potable water-washed flesh (one exchange; water:minced flesh ratio = 3.0) graded
SA (the highest possible grade for the "folding test used by Japanese
processors to test the gel strength of surimi". An A-B grade (second
and third grade on a five point scale) was assigned gels produced from
acid washed flesh.
Texture profile analysis of gels revealed acid washed flesh to
yield significantly lower gel elasticity (P [greater than or equal to] .007) and cohesiveness
(P [greater than or equal to] .0223) than those prepared from potable water washed flesh. The gels
were equal in hardness (P [greater than or equal to] .05). The two washing regimes produced gels
with comparable (P [greater than or equal to] .05) expressible water contents.
Low potable water (a single exchange; waterrminced flesh ratio =
3.0) and acidic (two exchanges; water:minced flesh ratio = 1.0/exchange;
exchanges = first pH 5.0-5.3, second potable water) washing regimes
improved surimi yield by 26 % and 34 %, respectively, over yields
reported for the conventional shore-based processing operations. This
was accomplished at water use levels conservatively estimated to be 20 %
of those reported for these processes. / Graduation date: 1987
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27435 |
| Date | 05 September 1986 |
| Creators | Pacheco Aguilar, Ramon |
| Contributors | Crawford, David L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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