- Machine separated flesh from American shad (Alosa
sapidissima) was evaluated for preparing heat set gel products.
Round fish frozen for 15) to 10 months at -18°C served as raw
material for processing investigations. The effectiveness of
various additives and processing procedures for improving gel
strength and sensory characteristics were determined.
Addition of 0.5% polyphosphate to sols enhanced the
hardness (P [greater than or equal to] .005), cohesiveness (P [greater than or equal to] .01) and springiness (P [greater than or equal to] .001)
of heat set gels. Small amounts (0.5 and 1.0%) of dried egg
white also improved hardness, cohesiveness and springiness
(P [greater than or equal to] .001). Employing a two stage heat setting regime (40°C for
30 min followed by 90°C for 20 min) strengthened (hardness,
cohesiveness and springiness) (P [greater than or equal to] .001) gels over a one stage
(90°C for 30 min) heat set. Two stage heating improved gel strength when sol fonnulations contained additives that
improved, lowered or exerted no effect on gel strength.
Concentrations of dried egg white (1.0, 2.0, 3.0 and 4.0%)
and potato starch (1.0, 2.0 and 5.0%) did not improve gel
strength. Dried egg white (>1%) did not alter (P > .05) any
physical parameters of gel texture. Potato starch (>1%) reduced
gel hardness (P [greater than or equal to] .001). More basic pH conditions produced by the
addition of 0.1 and 0.2% sodium carbonate to sols did not alter
gel hardness or springiness (P < .05) and only caused a slight
inprovement in cohesiveness (P [greater than or equal to] .001).
Ihe cryoprotectants sorbitol, (0.0, 2.0, 4.0, 6.0 and 8.0%)
and sucrose (0.0, 2.0, 4.0 and 6.0%), reduced gel strength in a
concentration dependent manner. Gel hardness was reduced in a
linear manner as fish protein was replaced with sorbitol
(r =.976) or sucrose (r =.965) in sols formulated to contain
74 + 1.5% moisture. Cohesiveness was reduced in a similar
manner (r = .942) by sorbitol, but not by sucrose. Gel
springiness was not altered by additions of sorbitol or sucrose.
Incorporation of sucrose into formulations reduced sensory
preference for the texture, flavor, appearance and overall
desirability of heat set gels. Analysis of covariance of
texture preference scores and physical measurements of texture
reveal a strong linear correlation with hardness (P =.0004), but
not with cohesiveness (P =.6675). Within the range of sucrose
levels evaluated, harder gels were preferred.
Washing was evaluated for improving the strength and
sensory preference for heat set gels containing 0.5% polyphosphate and 0.5% dried egg white. Sols were set by
heating for 30 min at 40°C followed by 90°C for 20 min and
exposed to wood smoke. Gel hardness and springiness were
reduced by washing (P [greater than or equal to] .05), but not cohesiveness (P > .05). This
was surprising, since the gel strength enhancing effect of
washing is well documented. Sensory preference for the flavor,
color, texture or overall desirability of heat set gels was not
affected (P > .05) by washing. Mean overall desirability scores
for gels prepared from unwashed minced flesh of 5.25 and 5.27
for washed minced flesh were only slightly above a neutral
preference (5.0 = neither like nor dislike).
Round shad yielded 65.06% planks, 41.20% minced flesh and
40.10% refined flesh. A single exchange wash followed by
dewatering yielded 23.02% pressed flesh based upon round weight
which was reduced to 20.68% by refining. Processing minced
flesh into washed and refined flesh recovered 51.37% of total
solids. The yield through refining was 97.33 and 89.83%
respectively for unwashed and washed flesh. The protein and
lipid content of flesh was not altered (P > .05) by washing, but
ash content was reduced (P [less than or equal to] .001).