INTRODUCTION
with starch was of 5.97 and 1.94 times higher than that of the
hairtailsurimi-based shrimp sample added with modified starch after
1.
Background
storage for 30 and 150 days, respectively.
Nowadays processes of surimi production in the world in general
5) The optimal additives concentrations and optimal mixing time
and Vietnam in particular have undergone grinding meat and washing
for processing of hairtail surimi-based shrimp product were of 2.7%
with acetic acid solution. The aim of these processes is to reduce the
modified starch, 1.1% sugar, 0.89% sorbitol, 0.05% shrimp flavour
odor, pigments or fat that affect to flavor of surimi as well as gel
and the mixing time was of 13-15 min.
forming ability. In fact, washing fish flesh with acid solution could
improve flavor and whiteness…but it could lead to decrease the gel
2. RECOMMENDATIONS
forming ability of muscle protein of fish. Thus, surimi and imitative
1) Further researches on using of modified starch in surimi
processing from different fish species need to be carried out.
2) The results from this study should be transferred to other
products have low water holding capacity, low gelling strength,
bending degree and organoleptic quality due to loss of muscle protein
and its denaturation during washing.
surimi processing companies in order to increase the quality of
In order to improve surimi quality, co-gelling additives with
surimi and surimi-based products. The training courses on how to
muscle protein of fish, such as starch are often used to increase water
produce the surimi and surimi-based products in following the
holding capacity and improve rheological properties. According to
proposed processes should be also carried out.
researches related to surimi and imitative products, adding starch
could improve product quality but during frozen storage its quality
decrease. In addition, each starch is suitable for some fish flesh.
Currently there are insufficient research data related to this field.
Hair-tail fish is a kind of trash fish. In Vietnam, annual production
of hair-tail fish was estimated about 400.000 ton, counting for 1/8 of
total harvested trash fish. Currently, most of hair-tail fish are used as
raw material for surimi production in almost surimi manufacturer.
Hair-tail has soft flesh, which is easily damaged when catching trash
fish by bottom pair trawling method. Using such material for surimi
production could lead to decrease its quality. Thus, some additives
24
1
such as polyphosphate are used to improve rheological properties of
surimi. However, the abuse of polyphosphates could increase food
CONCLUSIONS AND RECOMMENDATIONS
1. CONCLUSIONS
safety risk.
Therefore, the implementation of the thesis " Improvement of the
elasticity and gel strength properties of hairtail (Trichiurus
haumenla) surimi-based shimp product by using modified starches "
is needed to enhance quality and economic effects of surimi and
1) The optimal parameters for washing and dewatering stages in
the hairtalsurimi production process were as following: for washing
stage 1: fish meat was washed in 15.59% ethanol solution for 8.14
minat the ratio of fish meat to washing solution of 13.28%; the
optimal pressing force for dewatering was of 0.21kG/cm2;
imitative shrimp based on surimi.
2.
Scientific and practical applications
Results will contribute more scientific data for the field related to
surimi and surimi-based product. These scientific data could also
2) Have investigated the effects of modified starch concentration
on the quality of hairtailsurimi. The results obtained indicate that
the elasticity, folding grade and gel strength of hairtailsurimi
increased significantly at the added modified starch concentration of
update the textbook “Production of value-added aquatic products”
3%. Specifically, the gel strength value of the surimi sample added
that is used as main reference for teaching in Nha Trang university.
with 3% modified starch was of 2.42 times higher compared to that
Besides, research results will give the direction for Fisheries
Company Hoa Thang in order to improve surimi quality to meet the
criteria of Japanese and Korean markets.
3.
Objectives
of the surimi sample treated with starch.
3) The optimal additives concentrations for processing of hairtail
surimi were of 3.0% modified starch, 0.74% gelatine and 4.2%
sorbitol.
The objective of the thesis is to select washing solution that could
4) Have investigated the effects of modified starch concentration
limit negative effects on surimi quality due to washing, as well as
on the quality of hairtailsurimi-based shrimp product. The results
find out the additives and additive combination to increase elasticity
reveal that the quality of hairtailsurimi-based shrimp product
and gel strength of surimi and imitative shrimp from hairtail fish.
significantly increasedat the added modified starch concentration of
4.
Research contents
2.7%. The hairtailsurimi-based shrimp sample added with modified
1)
Determine chemical composition of hairtail fish –raw
starch had higher total sensory score, gel strength and lower drip
loss compared to those of the hairtailsurimi-based shrimp sample
material.
2)
Study on optimal conditions for washing fish flesh and
mixing modified starch in processing surimi from hairtail fish.
2
added with starch throughout the frozen storage time. Specifically,
the drip loss value of the hairtail surimi-based shrimp sample added
23
3)
Study on optimal conditions for mixing modified starch in
processing imitative shrimp from hairtail surimi.
4)
Effects of modified starch on quality of imitative shrimp in
frozen storage and heat treatment.
5.
Innovative
Figure 3.26. Principle component analysis (PCA) correlation
-
Using hairtail fish as new raw material in surimi production;
figure 3.26. Loadings for different parameters measured during
-
Alcohol solution (food grade) was used for washing flesh of
frozen storage of hairtail surimi-based shrimp product.
Abbreviations: HSTH, cooking yield; CQ, sensory quality; DBDK,
gel strength; DTSTG, drip loss.
Principal Component Analysis (PCA) was carried out in order to
gain over view of the similarities and differences among the
variables. The correlation loadings scores can be seen in Figure 3.26.
hairtail fish;
-
Using modified starch as a new additive in producing surimi
of hairtail fish;
-
Using modified starch as an additive to improve quality of
imitative shrimp based on surimi of hairtail fish;
-
Successfully transfering surimi production technology for
The results demonstrate that there was a positive correlation between
Fisheries company Hoa Thang that contribute to increase export
sensory quality, gel strength and cooking yield. These quality
capacity of this item to Japanese market.
parameters decreased with increasing storage time. Inversely, the drip
6.
loss increased with increasing storage time.
This thesis consists of 134 pages including: background (3 pages),
Layout of the thesis
chapter 1: Overview of research problems (40 pages); Chapter 2:
Methodology (22 pages); Chapter 3: Research outcomes and
discussions (59pages); Conclusion and recommendations (2 pages);
Bibliography (1 page); references (6 pages) listing 29 references in
Vietnamese and 63 references in English. It also consists of 19 tables
and 53 figures, 6 appendices.
22
3
PART 1. OVERVIEW OF RESEARCH PROBLEMS
In
recent
years,
surimi
industry
has
made
remarkable
achievements in our country, has expanded scale and production
capacity, domestic consumption and export market continously
increased. In the coming years, one of the main research goals is to
enhance the scientific and practical application in order to improve
the quality of surimi and imitative products for major export markets
such as Europe and Japan.
In our country, hairtail fish is one of the main raw material for
surimi production because of high harvest and common use in surimi
and imitative products. Due to softening and gapping texture of
muscle protein of the hairtail fish, gel strength, toughness of surimi
fish and imitative shrimp were low, there is a need to study on
washing, mixing additives to improve the elasticity, toughness, gel
strength of surimi and surimi shrimp product.
In surimi production technology, the main purpose of washing is
to remove fishy odor, fat and impurities, whitening muscle protein in
order to improve the organoleptic quality of surimi.
However, using acid or alkaline solution as cleaning agent coud
Figure 3.25. Changes in cooking yield of hairtail surimi-based
make a decrease of organoleptic quality, gel strength, and toughness
shrimp product during frozen storage as a function of modified
of shrimp surimi fish. Using alcoholic solutions in washing fish flesh
starch concentration
is a new approach that is an effort to solve the negative effect of acid
or alkaline solution.
DC-1: Control sample, DC-2: Sample with wheat starch added;
TBBT-2.70%: Sample with modified starch added of 2.70%
Modified starch technology is quite new technology, that continue
developing. Application of modified starch in surimi and imitative
shrimp is at the beginning and has achieved success in improving
elasticity, toughness, gel strength of surimi and surimi-based
4
I can be concluded that the samples added with modified starch
concentration of 2.70% had the highest cooking yield value.
3.5. Multivariate data analysis
21
No
Microbiological attribute (CFU)
Result
products. However, in our country and over the world, the use of
modified starch in surimi and surimi-based products is uncommon. In
1
Total viable count
8.2 x 102
2
Escherichia coli
Negative
3
Coliforms
Negative
4
Staphylococus aureus
5
Salmonella
Negative
shrimp during frozen and heating. The aim of the research is to
6
Vibrio cholera
Negative
provide new technology solutions in manufacturing surimi and
12
3.4. EFFECTS OF STORAGE TIME ON THE QUALITY OF
addition, there are insufficient scientific data about using modified
starches (cross-linked phosphate) in surimi production and imitative
shrimp from hairtail and the effect of modified starch (phosphate
cross-linked) was not investigated on product quality of surimi
imitative shrimp in Vietnam.
PART 2. MATERIAL AND METHOD
HAIRTAIL SURIMI-BASED SHRIMP PRODUCT
3.4.1. Effects of storage time on the gel strength, sensory
quality and drip loss of hairtail surimi-based shrimp product
The results obtained indicate that the gel strength and total
sensory score of hairtail surimi-based shrimp product decreased with
increasing storage time, whereas the drip loss increased. A significant
difference in gel strength value between the control sample and
sample added with modified starch. At the same storage time, the gel
strength value of the sample with 2.7% modified starch added was
2.1. Material
The object of the research is hairtail fish: Order: Perciformes;
Family: Trichiuridae; Genus Trichiurus; Species T. haumenla. Hairtail fish is caught in Khanh Hoa with the body length from 50 - 60
cm, 350 - 400 g/piece, raw fish meets in accordance with Vietnam
standard TCVN 3215:1988.
2.2. Method
In this study the traditional and modern methods such as
measuring food rheology, slicing frozen cells, stereoscopic
higher than that of other samples (i.e. without and with wheat starch
microscope were used. Besides, experimental planning and Design
added).
Expert 6.0 software were used, Unscrambler version 9.1 used to
It can be concluded that the hairtail surimi-based shrimp product
with 2.7% modified starch added had the highest total sensory score,
establish the mathematical model and optimize the parameters in data
processing.
gel strength value and the lowest drip loss value during the storage
2.3. Equipment, chemicals, additives for research
period.
- Rheometer, frozen cell slice machine; distillation equipment for
3.4.2.Effects of modified starch concentration on the cooking yield of
hairtail surimi-based shrimp product during frozen storage
20
protein, stereoscopic microscopes, handle equipment, laboratory
instruments;
5
- The additives used in the study are highly purified, ensuring reliable
+Additives mixing:Theadditive concentrations used were of 2.70%
for analyzing.
modified starch, 0.89% sorbitol, 1.10% sugar and 0.05% shrimp
PART 3. RESEARCH RESULTS
flavour.
3.1. Mass and chemical composition of hair-tail fish
+Mixing: The mixture was mixed for 13 - 15 min.
The results showed that hairtail fish consists meat 40.8%, head
+ Forming: The mixture was then formed of shrimp based
13.2%, skin, cartilage, bones, fins 39.6%, organs 6.4%. Chemical
product.
composition consists water 77.98%, protein 16.82%, lipid 1.35%.
Hairtail is low-fat fish, the flesh is white, so suitable as raw materials
for producing surimi. However, fish flesh accounted for only 40.8%
of the total weight, lower than that of sardines, horsehead fish.
Hairtail fish has the specific structure. Its muscle fibers is quite short
+Stabilizing:Thehairtail
surimi-based
shrimp
product
was
stabilized for 1h at room temperature.
+ Vacuum packaging and storage: The final product was
vacuum-packaged and stored at the temperature ≤ -180C.
and loose that negatively affect on surimi quality, especially elasticity
3.3.5.Quality evaluation of hairtail surimi-based shrimp product
and gel strength.
produced by proposed process
Table 3.20. Quality attributes of hairtail surimi-based shrimp
3.2. Effect of technological factors on elasticity, gel strength of
product
frozen surimi
3.2.1. Studies on fish washing with an alcohol solution
3.2.1.1. Effect of alcoholic solutions on gel strength of surimi
The correlation of three factors (the alcohol content, ratio of fish
meat to washing solution, duration) and gel strength of surimi is
represented by the regression equation as follows:
No
Quality attribute
Result
1
Gel strength (g.cm)
578
2
Folding grade
A
3
Texture
4
Colour
Elasticity
Specific
X1Y1 = 363.5 + 26.8 X1 + 31.3 X2 - 9.5 X3 - 22.5 X1 X2 (3.1)
solution, the shorter washing duration.
of
steamed
shrimp
There is a correlation between alcohol concentration. The higher
alcohol concentration, and the lower ratio of flesh to washing
colour
5
Odour
Specific odour of cooked shrimp
6
Taste
Specific taste of cooked shrimp
Table 3.21. Microbiological quality of hairtail surimi-based
shrimp product
6
19
Table 3.5. Experimental data and data from the regression
MS:
2.70%
Additives mixing
equation
Shrimp
Factor
flavour 0.05%
Sorbitol: 0.89%
No
X1
Sugar: 1.10%
Gel strength (g.cm)
X2
X3 Data from equation Experimental data
1
13,59 19,24
7,88
365,60
365,00
2
14,59
21,95
14,33
339,88
338,00
3
15,59
13,28
8,14
435,37
436,00
Forming
4
16,59 18,11
13,06
372,17
370,00
Mixing
13-15 min
Results (Table 3.5) showed that there is a high correlation
Stabilizing
1h,room temp
Freezing
between data from equation and experimental results. Thus,
regression equation is reliable. The results also showed that optimum
parameters of fish washing are concentration of alcohol solution
15.59%, the ratio of fish flesh to solution 13.28% and duration 8.14
Packaging and
storage
Figure 3.20. Flowchart of hairtail surimi-based shrimp
minutes, that could obtain maximum gel strength of surimi.
3.2.1.2. Effect of alcohol solution, fluctuated around optimal
point on bending degree and organoleptic quality of surimi
Table 3.6. Effect of alcohol solution on bending degree and
product
organoleptic quality of surimi
Process explaining
+Rawmaterial:Hairtailsurimi was produced according to the
proposed production process. The quality of hairtail surimi was
ranked the first grade in accordance with Vietnam standard TCVN
8682-2011.
+Thawing and draining: in order to recover the rheological
properties of surimi before freezing.
Concentration of alcohol solution (%)
Criteria
15,55
15,57
15,59
15,61
15,63
Bending degree
AA
AA
AA
AA
A
Sensory
18,28
18,37
18,65
18,68
18,52
evaluation
(mark)
Results verifing the influence of alcohol solution, fluctuated
around optimal point showed that there is a high correlation between
18
7
organoleptic quality, bending degree, gel strength and alcohol
The results obtained demonstrate that the total sensory score and
concentration.
gel strength of hairtail surimi-based shrimp product significantly
3.2.2. Quality comparison of surimi washed once with alcoholic
depended on the mixing time (Table 3.18). The highest sensory score
solution with surimi washed once with acid solution
of shrimp was found at the mixing time of 13 min and the highest gel
In comparison of surimi washed with alcohol solution with surimi
washed with 0.03% acetic acid solution there was a sharp increase
gel strength of surimi (reached 438 g.cm, an increase 1.32 times)
strength value was observed at the mixing time of 15 min. Therefore,
the suitable mixing time was in the range of 13-15 min.
3.3.3. Effects of shrimp flavour concentration on the sensory
when washing with alcohol. Similarly, sensory mark got 18.70,
quality of hairtail surimi-based shrimp product
higher than 1.09 times with surimi washed with 0.03% acetic acid
Table 3.19. Changes in sensory quality of hairtail surimi-based
solution.
shrimp product as affected by shrimp flavour concentration
Quality attribute
Total
sensory
Shrimp flavour concentration (%)
score
0.03
0.04
0.05
0.06
0.07
18.17
18.32
18.74
18.70
17.24
(score)
The results reveal that at the shrimp flavour of 0.05%, the total
sensory score of hairtail surimi-based shrimp product was the
Figure 3.4. Muscle structure of hairtail fish – raw material
(A), after washing once a 0.03% acetic acid (B), after washing
once with 15.59% alcohol solution (C)
Tomography images of cells and tissue structures of hairtail fish
highest. Hence, shrimp flavour concentration of 0.05% was used for
hairtail surimi-based shrimp product processing.
3.3.4. Proposed production process of hairtail surimi-based
shrimp product
muscle measured with stereoscopic microscope Olympus IX 70
Frozen hairtail
showed that the raw fish flesh has high fat content marked by pale
surimi
streaks. Samples washed with 0.03% acetic acid solution, lipid
streaks still remain, that less than the remaining amount of lipid in
Thawing and
raw material (Figure 3.4b). On the other hand, there was near absence
draining
8
17
The results obtained indicate that the folding grade and sensory
quality of hairtail surimi-based shrimp product were rather stable at
different additive concentrations. At the optimal concentration of
of lipid in samples washed with 15.59% alcohol solution. It is proved
that lipid removed (Figure 3.4C).
3.2.3. Effect of dewatering by pressing on surimi quality
additives (i.e. modified starch, sorbitol and sugar), the gel strength
value and total sensory score were the highest (Table 3.17).
Table 3.7. Effects of dewatering pressure on gel strength, bending
degree and sensory evaluation
2
Press force (kG/cm )
0,17
0,19
0,21
0,23
0,25
A
AA
AA
A
B
Gel strength (g.cm)
378
402
458
415
384
Sensory evaluation (mark)
15,69
16,52
18,08
17,78
16,44
Bending degree
Figure 3.16. The microstructure of hairtail surimi-based shrimp
product treated with modified starch
highest gel strength and bending degree with press force 0.21
Figure 3.16 shows transverse sections of hairtail surimi-based
shrimp product that has been treated with modified starch. It is
clearly seen that the added modified starch was interwoven into the
gel structure of protein (the white colour area). This led to increase
the gel strength, elasticity and folding grade of surimi.
gel strength of hairtail surimi-based shrimp product
score
strength of hairtail surimi
are shown in regression equation 3.2.
The regression equation (3.2) indicated that the gel strength of
9
11
13
15
17
18.17
18.32
18.74
18.70
17.24
391
497
576
579
516
(score)
Gel strength (g.cm)
3.2.4. Effects of modified starch on the gel elasticity and gel
Y2 = 847.75 +15.25X1+ 6.00X2 + 5.50X3 - 5.5X1X3 – 7.25X2X3 (3.2)
Mixing time (min)
sensory
washing fish flesh in surimi processing (table 3.7).
The effects of additive concentration on the gel strength of surimi
Table 3.1. Effects of mixing time on the total sensory score and
Total
kG/cm2. Thus, press force 0.21 kG/cm2 was chosen to dewater after
3.2.4.1. Determination of optimal additive concentration
3.3.2. Determination of optimal mixing time
Quality attribute
Results showed that surimi obtained the best sensory quality, the
surimi increased with increasing the additive concentration. The
surimi added with modified starch had the strongest effect on the
gel strength followed by surimi treated with gelatin and sorbitol.
16
9
Table 3.10. Results of optimizing percentage of additives
added to surimi by regression and experiment
Factors
X1
X2
of hairtail surimi-based shrimp product according to the
regression equation and experimental results
Gel strength (g.cm)
No
Data from
X3
equation
Table 3.16. Effects of additive concentration on the gel strength
Additive concentration
Experimental data
1
2,62
0,87
3,88
832,79
831,00
2
2,72
0,70
4,06
339,88
339,00
3
2,99
0,85
3,99
863,27
860,00
4
3,00
0,74
4,20
864,01
866,00
No
X1
X2
Gel strength (g.cm)
X3
Regression equation
Experimental
result
result
1
13.59
19.24
7.88
365.60
365.00
2
14.59
21.95
14.33
339.88
338.00
3
15.59
13.28
8.14
435.37
436.00
4
16.59
18.11
13.06
372.17
370.00
Results of evaluating gel strength of the frozen surimi were shown
The results indicate that the gel strength values of hairtail surimi-
in table 3.10. There is a compatibility between the gel strength of
based shrimp product followed by the regression equation were in
surimi samples calculated by regression equation and experimental
compatibility with the experimental results. Therefore, the regression
results.
equation obtain in this study was acceptable.
3.2.4.2. Effects of modified starch of the folding grade and
3.3.1.2. Effects of modified starch concentration on the folding
sensory quality of hairtail surimi
grade and sensory quality of hairtail surimi-based shrimp
Table 3.11. Effects of modified starch concentration on the
product
folding grade and sensory quality of hairtail surimi
Table 3.17. Changes in folding grade and sensory quality of
Modified starch concentration (%)
hairtail surimi-based shrimp product as a function of modified
2.96
2.98
3.00
3.02
3.04
starch concentration
A
AA
AA
AA
A
18.80
18.89
18.77
18.55
(%)
The results demonstrate that the highest folding grade and total
2.66
2.68
2.70
2.72
2.74
Folding grade
B
A
A
A
B
Total sensory score (score)
18.46
18.80
18.89
18.77
18.55
Quality attribute
Folding grade
Total sensory score (score) 18.46
sensory score of hairtail surimi were obtained at the modified
starch concentration of 3%.
10
Quality attribute
Modified starch concentration
15
The results reveal that the gel strength of hairtail surimi-based
shrimp product increased with increasing the additive concentrations
(i.e. modified starch, sorbitol and sugar) (Eq. 3.3). Added sugar
showed the strongest effect on the gel strength, followed by sorbitol
and modified starch (Figure 3.13).
Y3 = 560.40 + 7.00X1 + 22.50 X2 + 23.25 X3 – 17.00 X1 X2 – 16.00 X1 X3 –
Figure 3.9. The microstructure of surimi treated with 3%
modified starch
11.45X12 – 31.45X22 (3.3)
The microstructure of surimi was examined by microscope
Gel strength (g.cm)
OLYMPUS IX70. Figure 3.9 shows transverse sections of surimi that
Sorbitol (%)
has been added with 3% modified starch. It is clearly seen that the
added modified starch reacted with water, resulting in removal spaces
where the free water was stored in. This led to increase the gel
strength, elasticity and folding grade of surimi.
It could be concluded that the optimal additive concentrations in
A
B
hairtail surimi processing were of 3.0% modified starch, 0.74%
Gel strength (g.cm)
gelatin and 4.2% sorbitol.
3.2.5.Proposed production process of hairtail surimi
Sugar (%)
Raw material
C
↓
Treating
↓
D
Mincing
Figure 3.13. Changes in gel strength of hairtail surimi-based
↓
shrimp product as functions of sugar, sorbitol and gelatin
Pre-dewatering
concentrations
14
11
and 3.13, respectively. In comparison with the Vietnam standard for
↓
frozen surimi (TCVN 8682:2011), the quality of hairtail surimi produced
Washing
by proposed process was ranked the first-grade of frozen surimi product.
Washing 1
Washing in 15.59% ethanol for 8.14 min; V/W =
13.28%
Washing 2
Washing in 0.5% NaCl for 10 min; V/W = 17%
Washing 3
Washing in water for = 10 min; V/W = 17%
Table 3.12. Quality attributes of hairtail surimi produced by
proposed process
No.
↓
0.21kG/cm2 →
Dewatering
Time 10min →
↓
Additive mixing
Gelatin 0.74 %
Sorbitol 4.2%
Modified starch 3.0%
↓
1
Water content (%)
77.48
2
Protein content (%)
12.24
3
Lipid content (%)
0.08
4
pH
6.8
5
Gel strength (g.cm)
867
6
Folding grade
7
Texture
Elasticity
8
Colour
White
9
Odour
Very slight fishy
A
by proposed process
↓
Forming
Result
Table 3.13. Microbiological quality of hairtail surimi produced
Mixing
2h →
Quality attribute
← Room temp
Microbiological attribute (CFU)
Result
Salmonella
ND
↓
Freezing, packaging and storage
Figure 3.12. Flowchart for hairtail surimi processing
ND: Not detected
3.3. Effects of additive concentration on the quality of Hairtail
surimi
3.2.6. Quality evaluation of hairtail surimi produced by proposed
3.3.1. Determination of optimal additive concentration
process
3.3.1.1. Effects of modified starch on the gel strength of
The results of physicochemical properties and sensory evaluation and
hairtail surimi-based shrimp product
microbiological assessment of hairtail surimi are shown in Table 3.12
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