This study was carried out to determine the effects of Microbial Transglutaminase (MTGase) and isolated soy protein (ISP) on tilapia (Oreochromis niloticus) surimi gels. MTGase at 0, 0.3, 0.6 percent and ISP at 0, 3 and 6 percent were added to surimi gels of tilapia.

1. Table 2. Protein (%) and fat (%) content of tilapia surimi gels
a-c: letter distinct mean difference
(P<0.05) between samples
Table 1. Changes of surimi gels color and WHC at various concentrations of
MTGase and ISP
Color Measurement
Color measurement was made
using a colori-meter (Minolta CR
300, Japan). The color reading
includes lightness (L), redness (a)
and yellowness (b). The
equipment was standardized with
a white color standard.
Whiteness was calculated as
whiteness = L* - 3b* (Park, 2000),
where L* = lightness on a 0-100
scale from black to white, a* =
scale of red (+) or green (-), b*=
scale of yellow (+) or blue (-)
(Tabilo and Barbosa, 2004).
Water Holding Capacity (WHC)
The amount of water holding
capacity for each treatment was
measured. Samples of 3 ± 0.1 g
of cooked gels were weighed and
put between two layers of filter
paper (Whatman No. 1).
Samples were then placed at the
bottom of 50 ml centrifuge tubes
and centrifuged at 1500 g for
5 min at 15°C. Immediately after
centrifugation, the fish sample
was removed and weighed
(Ramirez et al. 2007). Three
samples were analyzed for each
treatment and average values
were recorded. The amount of
WHC was calculated as follows:
Initial weight
WHC (%) =
Initial weight – Final Weight X 100
Initial weight
(Ramirez et al. 2007)
Proximate Analysis (Protein
and Fat)
Protein and fat analysis of gel of
tilapia surimi were determined
according to the method of AOAC
(1999).
EFFECT OF MICROBIAL TRANSGLUTAMINASE (MTGASE) AND
ISOLATED SOY PROTEIN (ISP) ON PHYSICOCHEMICAL
PROPERTIES OF TILAPIA SURIMI GELS
Hazmi, Y., Babji, A.S., and Norrakiah, A.S.
School of Chemical Sciences and Food Technology, Bangi, UKM
E.mail: daging@ukm.my
Abstract
This study was carried out to
determine the effects of Microbial
Transglutaminase (MTGase) and
isolated soy protein (ISP) on
tilapia (Oreochromis niloticus)
surimi gels. MTGase at 0, 0.3,
0.6 percent and ISP at 0, 3 and 6
percent were added to surimi
gels of tilapia. Analyses were
carried out in surimi gels
including physical and chemical
analyses, which include color,
water holding capacity (WHC),
and proximate analyses. The
addition of MTGase and ISP
affected the whiteness of tilapia
surimi gels. This study only used
L*, b* and whiteness (W) as
parameters, because of their
effectiveness to distinguish ISP
and MTGase influence. WHC
and whiteness showed positive
and negative correlation with the
addition of MTGase and ISP in
tilapia surimi gels. WHC and
whiteness increased as MTGase
was increased. But for ISP,
WHC and whiteness decreased
with increased ISP. Proximate
analysis recorded that fat and
ash analysis gave no significant
difference (P<0.05) with the
addition of MTGase and ISP in
tilapia surimi gels. For protein
analysis, addition of ISP affected
protein analysis in tilapia surimi
gels. The more ISP added, the
more protein value increased.
Keywords: Surimi, tilapia,
MTGase, ISP
Objectives
To determine the effect of
microbial transglutaminase
(MTGase) and isolated soy
protein (ISP) on water holding
capacity (WHC), proximate
analysis and color attributes of
surimi gels from tilapia
(Oreochromis niloticus).
Methods Results and Discussion
References
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Association of Official Analytical Chemists16th edition.
Cunnif P Ed, AOAC International Gaithersburg MD
USA.
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of Mackerel (Rastrelliger branchysoma) Protein Isolate
as Affected by Microbial Transglutaminase. Food
Chemistry, 121: 85-92.
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of sugars on the characteristics of glucono-[delta]-
lactone-induced soy protein isolate gels. Food
Hydrocolloids. Doi:10.1016/j.foodhyd.2008.01.005.
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usefulness of transglutaminase for food processing. In
“Biotechnology for improved food and flavors ACS
Symposium”. pp. 29-38. Takeoka, G. R., Teranishi, R.,
Williams, P. J. and Kobayashi, A. ed. Washington, DC,
U.S.A.
• Park, J.W. 2000. Ingredient technology and formulation
development. In Surimi and Surimi Seafood.(Park, J.W.,
ed.). pp. 343-392. Marcel Dekker. New York.
• Ramírez, J. A., Del Ángel, A., Uresti, R. M., Velazquez,
G. & Vazquez, M. 2007. Low-salt restructured products
from striped mullet (Mugil cephalus) using microbial
transglutaminase or whey protein concentrate as
additives. Food Chemistry 102: 243-249.
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Ind. Hi-Tech, 13, 30-33.
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Color and textural parameters of pressurized and heat-
treated surimi gels as affected by potato starch and egg
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• Tay, S.K., Xu, G.Q. and Perer, C.O. 2005. Aggreagation
profile of 11S, 7S and 2S coagulated with GD L. Food
Chem. 91, 457-462.
Color Measurement
The experimental values for
tilapia surimi gels color (L*, b*
and whiteness) under different
binding agents were presented in
Table 1. Generally, the increasing
of whiteness of tilapia surimi gels
occurred when MTGase was
increased, but the different results
showed by increasing of ISP. The
decreasing of whiteness when
lSP level was increased, might be
due to the unexpected salt or
metal ions were present in the
powder. Chaijan and Panpipat
(2010) stated that if salt or metal
ions were present in the enzyme
powder, these compounds could
enhance the discoloration of the
resulting gels to some extent. For
MTGase, the whiteness
increased when MTGase level
was increased, which might be
due to Maillard reaction and the
oxidation of lipids and myoglobin.
Water Holding Capacity
In general, WHC of surimi gels
increased when the concentration
of MTGase increased. The
highest result were quite similar
with Kuraishi et al. (1996), which
reported that the WHC of proteins
could be enhanced by MTGase
either by increasing their ability to
swell and to take up water by
improving their ability to form a
gelling network.
Regarding the effect of the
addition of MTGase and ISP,
significant differences (P<0.05)
were found in surimi gels from
tilapia only for the addition of
MTGase. When ISP combines
with MTGase, the slightly
decrease of WHC occurred, only
when ISP increased. The
decrease of WHC as affected by
ISP could be due to glycation (the
result of the bonding of a protein
or lipid molecule with a sugar
molecule without the controlling
action of an enzyme (Ahmed and
Furth,1992)) of ISP decreased its
WHC, due to decreasein net
charge via Maillard reaction (Gu
et al., 2008).
Tay et al. (2005) stated that the
thermally induced soy protein
gelation is not easily controlled,
and the formed gels are coarse
and stiff with poor WHC.
Proximate Analysis (Protein
and Fat)
Proximate analysis provides
information for various types of
processing. Tilapia is a fish that
has a low fat content but has a
high protein content. Proximate
analysis of surimi gel from tilapia
is shown in Table 2.
In tilapia surimi gels, with the
addition of isolated soy protein,
the more isolated soy protein
added, the more value of the
protein gel surimi from tilapia
increased (P <0.05). This was
occured because the isolated
soy protein containing about 5%
moisture, 91% protein, ~ 0% fat,
~ 0% carbohydrate, and 4% ash
(Stauffer, 2002).
International Seminar on Food & Agricultural Science 2012. 4-6 Sept 2012, Puri Pujangga, UKM
Treatment L* b* W* WHC
Control 74.06±0.84b 2.68±0.12e 66.00±0.76a 7.98±1.31b
3% ISP 70.67±0.75c 4.16±0.17d 58.17±1.00b 6.83±1.18c
6% ISP 68.74±0.37c 5.00±0.20c 53.71±0.89c 5.42±1.31d
0.3% MTGase 69.99±0.80c 2.27±0.34ef 61.32±1.74b 11.14±1.24ab
0.6% MTGase 72.11±2.05b 2.08±0.48f 65.85±0.88a 14.26±2.44a
3% ISP & 0.3% MTGase 83.13±0.67a 5.81±0.18b 66.01±0.76a 8.22±2.15b
3% ISP & 0.6% MTGase 79.87±0.91b 5.13±0.23c 64.47±1.22a 7.99±1.04b
6% ISP & 0.3% MTGase 67.38±0.80d 5.70±0.26b 50.27±0.62d 6.56±3.17cd
6% ISP & 0.6% MTGase 69.15±2.13c 6.47±0.54c 49.73±1.96d 5.26±0.73e
Treatment Protein (%) Fat (%)
Control 15.05c 2.80a
3% ISP 19.42b 2.92a
6% ISP 26.16a 2.94a
0.3% MTGase 15.31c 2.91a
0.6% MTGase 15.66c 3.05a
3% ISP & 0.3% MTGase 15.40c 3.05a
3% ISP & 0.6% MTGase 15.84bc 2.16a
6% ISP & 0.3% MTGase 16.36bc 3.08a
6% ISP & 0.6% MTGase 17.06b 2.52a
Acknowledgement
a-f: letter distinct mean difference (P<0.05) between samples
The authors are grateful to the
Fisheries Research Institute, Batu
Maung, Penang as this work was
supported financially under the
grant no. STGL-009-2007.