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Improving the Physicochemical Properties of Commercial Bovine Gelatin using Succinylation

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Commercial bovine gelatin was modified by using succinic anhydride and resultant changes in physicochemical properties such as Bloom strength, foaming properties and extent of succinylation were investigated. The result indicated that addition of succinic anhydride at varying concentrations of 0.04, 0.08, 0.12 and 0.16 g/g of sample increased the degree of succinylation from 0% to 14%, while Bloom strength increased from 131.97% to148.60% but at higher concentration decreased from 133.50% to128.0%. Foaming capacity increased from 171.67% to 210.70% but a substantial constant decrease in foaming stability with time.
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ISSN: 2338-1345 Vol. (5). 2-6 2017 Journal online http://journal.bakrie.ac.id/index.php/APJSAFE
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Asia Pacific Journal of Sustainable Agriculture Food and Energy (APJSAFE)
Improving the Physicochemical Properties of Commercial Bovine
Gelatin using Succinylation
Nur Aliyana Binti Alias1, Benedict Oludare Omosebi2, Wahyudi David3 and Nurul Huda4*,
1Food Technology Program, Universiti Sains Malaysia, Penang, 11800, Malaysia
2Department of Food Technology, Federal Institute of Industrial Research , Oshodi, Lagos State, Nigeria.
3Department of Food Science and Technology, Universitas Bakrie, Jakarta, Indonesia
4School of Food Industry, Universiti Sultan Zainal Abidin, Besut Campus, 22200, Terengganu, Malaysia
*Corresponding author’s Email address: nhuda@unisza.edu.my
Abstract- Commercial bovine gelatin was modified by using succinic anhydride and resultant changes in physicochemical
properties such as Bloom strength, foaming properties and extent of succinylation were investigated. The result indicated tha t
addition of succinic anhydride at varying concentrations of 0.04, 0.08, 0.12 and 0.16 g/g of sample increased the degree of
succinylation from 0% to 14%, while Bloom strength increased from 131.97% to148.60% but at higher concentration decreased
from 133.50% to128.0%. Foaming capacity increased from 171.67% to 210.70% but a substantial constant decrease in
foaming stability with time.
Keywords- Gelatin, Succinic anhydride, gel strength, foaming capacity, physicochemical properties,
INTRODUCTION
Gelatin is a biopolymer which is tasteless, highly
purified and a collagenous protein ingredient. Gelatin is
derived by the partial hydrolysis of collagen, the principal
protein constituent of animal skin, bone and connective
tissue. Presently gelatin is used in the food,
pharmaceutical, cosmetic and photographic application
(Karim and Bhat, 2009). In food, gelatin is mainly used to
improve elasticity, consistency and stability of foods and
provides a melts in mouth function with a thermo-
reversible gel property. Research by Grand View
Research (2014) stated that pigskin was the largest used
raw material for the manufacturing of gelatin which
accounts for more than 40% of the global gelatin
production in 2013. Karim and Bhat (2009) and Gómez-
Guillén et al., (2011) also reported that the annual world
output of gelatin is nearly 326000 tons, with pig skin-
derived gelatin accounting for the highest (46%) output
followed by bovine hides (29.4%), bones (23.1%) and
other sources (1.5%).
The quality of food grade gelatin depends to a large
extent on its rheological characteristic such as viscosity and
viscoelastic properties (Karim and Bhat, 2009). Nowadays,
modification of gelatin has been done by many researchers
to improve gelatin functionality especially for low quality
gelatin and therefore, increase gelatin acceptability for
other application. Modification of gelatin can be done
enzymatically, physically and chemically. Chemical
modification has been an acceptable alternative for
improving protein functional characteristic as well as
tailoring a protein to meet a specific characteristic for a
given food system.
Succinylation is one chemical modification method to
improve the functionality of protein (Mahaja et. al., 2010;
Shilpashree et al, 2015). Beside through succinylation,
chemical modification of protein can be conducted through
acetylation (; Miedzianka et al. 2012) and glycation (Liu et
al., 2012). In succinylation, succinic anhydride reacts with
the ε-amino group of lysine and the N-terminal α-amino
group of proteins, in their nonprotonated forms converting
them from basic to acidic group (Klapper and Klotz, 1972).
In general, functional properties such as solubility and
emulsification capacity were improved by succinylation
(Kabirullah and Wills, 1982). Groninger, (1973) studied
that emulsification capacity of succinylated myofibrillar
protein was related to the degree of succinylation of the
protein. Oppenheimer et al., (1967) showed that
succinylation of chicken protein resulted in a product that
had increased viscosity, but molecular size similar to that
unmodified myosin. Succinylation also improves the
emulsion activity, emulsion stability and increase water
absorption capacities of lentil globulin (Bora, 2002).
This project was carried out to determine the effect of
different level of succinic anhydride modification on the
physicochemical properties such as Bloom strength and
foaming properties of commercial bovine gelatin.
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MATERIALS AND METHODS
Materials
Commercial gelatin from bovine source purchased from
Leverage Business Sdn Bhd (Penang, Malaysia) was used
as the main sample. Succinic anhydride 99% was
purchased from Acros Organic (New Jersey, USA).
Ninhydrin (Fluka), 95% ethanol, acetic acid and glycine
from Sigma (USA) were used for determination extent of
succinylation.
Succinylation of gelatin
Succinylation of commercial gelatin was performed
according to the method of Groninger (1973) with some
modifications. Commercial gelatin (4 g) was dispersed in
160 ml distilled water (2.5 % w/v) and left to room
temperature for gelatin to dissolve. Gelatin then melted at
60 °C to until completely dissolved and cooled to room
temperature. Succinic anhydride was added in small
increments with constant stirring (Eurostar Digital, IKA-
WERKE, Germany) at level of 1, 2, 3 and 4 % weight of
sample. pH of the mixture was maintained at 7 by adding 1
N NaOH in order to prevent further modification. Control
was prepared with same procedure without the addition
succinic anhydride. The mixture was freeze dried prior to
analysis.
Determination of extent of succinylatiion.
The extent of succinylation was conducted as described by
Kinsella et al., (1976). Ninhydrin solution (1 ml) was
added to aqueous protein solution (1 ml). 4 ml of distilled
water was added to each tube. The mixture then was placed
in boiling water bath at 100 °C for 5 min. The absorbance
of sample was read at 580 nm against ninhydrin solution
blank. The extent of succinylation was calculated as follow
formula:
Determination of Bloom strength.
Bloom strength of gelatin was determined according to
the method Gelatin Manufacturer Institute of America
(GMIA, 2014). 6.67% (w/v) of gelatin solution was
prepared in bloom jar at room temperature. The mixture
was left at room temperature for 10 minutes to allow
gelatin to absorb water and swell. Gelatin solution then left
to melt at 60 °C until gelatin completely dissolve and
cooled to room temperature before kept in a refrigerated
water bath at 10 °C for 16 to 18 hour for gel maturation.
The gel strength was determined by using texture analyser
TA.XT2 (Stable Microsystems, Surrey, UK) with a load
cell of 5 kg equipped with flat bottom plunger 0.5 mm in
diameter (SMS P/0.5). Gel strength (in grams) was
obtained after plunger penetrates into gel to a depth of 4
mm at rate 0.5 mm/s.
Determination of foaming properties.
Foaming stability and foaming expansion of gelatin
solution were measured according to the method des cribed
by Shahidi et al., (1995). 2% (w/v) of sample was prepared
and swollen. Sample then dissolved at 60°C and
homogenized at 10,000 rpm (IKA T25 digital, Germany)
for 2 minutes to produce foam. The mixture was poured
into 100ml measuring cylinder and the total volume was
read. The sample was allowed to stand at 0, 20, 40 and 60
minutes. Foaming stability and foaming expansion were
calculated using following formula:
Where, VT = total volume after whipping, Vo = original
volume before whipping and
Vt = total volume after leaving at room temperature for
specific time.
Statistical Analysis
SPSS software (SPSS 17.0 Statistical Package for
Social Science) was used to evaluate the chemical analysis,
and physical analysis data. Comparison of means among
the different samples was conducted us ing Duncan’s
multiple range test.
RESULT S AND DISCUSSIONS
Determination extent of succinylation
The Figure 1 shows the extent of succinylation of
gelatin. The extent of succinylation of amino groups in the
gelatin depends markedly on the amount of succinic
anhydride being added. Incremental addition of succinic
anhydride at 0.04, 0.08, 0.12 and 0.16 g/g of sample
succinylated 3.68%, 8.10%, 10.92% and 13.14%
respectively of the ɛ-amino groups. The result indicates
that level of succinylation increased as the quantity of
succinic anhydride increased.
Figure 1. Extent of succinylation of gelatin
The protein acylation reactions presumably follow the
carbonyl addition pathway and the rate of reaction depends
on the rate of nucleophilic attack (Means and Feeney,
1971). High reactivity of protein group are readily acylated
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compared with other amino acid residue and group that
generally higher pK and are usually more protected from
the reaction than amino groups (Franzen and Kinsella,
1976). The amino and hydroxyl groups of a protein are
readily acylated compared with the other amino acid
residues available for the reaction (Lawal, 2005). The ɛ-
amino group of lysine is most readily acylated because of
its high nucleophilic character, relatively low pK and its
steric availability for reaction (Franzen and Kinsella, 1976;
Wanasundara and Shahidi, 1997).
Bloom Strength
The most important attribute of gelatin is its Bloom
strength. Bloom strength is the weight in grams that is
required for a specified plunger to depress the surface of
standard, thermostated gel to a defined depth under
standard conditions (Schrieber and Gareis, 2007). Table 1
shows the Bloom strength of gelatin with and without the
addition of succinic anhydride.
Table 1. Bloom strength of gelatin with different level of
modification
Sample
Bloom
strength
(g)
Improve
ment effect
(%)
Percentage
effect (%)
Control
131.97 ± 0.55c
-
-
3.68% SG
134.20 ± 0.50b
2.23
1.69
8.10% SG
148.60 ± 0.50a
16.63
12.60
10.92% SG
133.50 ± 0.44b
1.53
1.16
13.14% SG
128.03 ± 0.56d
-3.94
-2.99
SG = Succinylated Gelatin
Values are presented as mean ± SD (n = 3)
Different subscript letters within the same row indicate
significant differences (p< 0.05)
As noticed in table, addition of succinic anhydride
into gelatin increases the Bloom strength up to certain
point. Addition of succinic anhydride into gelatin slightly
increases the Bloom strength for 3.68% SG (134.20 ± 0.50
g) and 8.10% SG (148.60 ± 0.50 g) with percentage effect
1.69% and 12.60%. However, increase in the
concentration of succinic anhydride beyond 8.10% SG
resulted in the decline of the Bloom strength. The Bloom
strength of gelatin start to decrease at 10.92% SG (133.50
± 0.44 g) and 13.14% SG (128.03 ± 0.56 g), hence
lowering percentage effect. According to Schrieber and
Gareis (2007), the Bloom strength of commercial gelatin
types are within the range 50 to 300 Bloom. Bloom
strength is dependent on the hydrogen bonds between
water molecules and free hydroxyl groups of amino acids,
size of protein chains, concentration and molecular weight
distribution of the gelatin (Arnesen and Gildberg, 2007).
Decreased in Bloom strength might be due to excessive
cross-linking that might lower gel strength through
impeding intermolecular aggregation that reduced the gel
network formation (Jongjareonrak et al., 2006).
Foam Capacity
Gelatin and soluble collagen exhibit suitable foaming
properties, even without gelling, because of their ability to
reduce the surface tension at the liquid or air interface by
increasing the viscosity of the aqueous phase (Schrieber
and Gareis, 2007). Table 2 shows the effect of
succinylation on foam capacity of gelatin.
Table 2. Foaming capacity of gelatin with different level of
modification
Sample
Foaming
Expansion
(%)
Percentage
effect (%)
Control
171.67 ± 0.76e
-
3.68% SG
185.67 ± 0.38d
9.32
8.10% SG
194.17 ± 0.29c
13.11
10.92% SG
198.23 ± 0.25b
15.47
13.14% SG
210.70 ± 0.66a
22.73
SG = Succinylated Gelatin
Values are presented as mean ± SD (n = 3)
Different subscript letters within the same row indicate
significant differences (p< 0.05)
The foam capacity of all samples increased
significantly (p< 0.05) after treated with succinic
anhydride. At 7.5% SG, the foam capacity was 185.67 ±
0.38, which means it increased 9.32% from control gelatin.
The percentage effect of foam capacity of succinylated
gelatin increased to 13.11% when with 8.10% SG was
added, 15.27% when 10.92% SG was added and 22.73%
when 13.14% SG was added . The result emphasized that
succinylation was able to improve foam capacity. These
observation agree with those reported for canola 12S
globulin (Paulson and Tung, 1987), milk protein
(Shilpashree et al, 2015), and mung bean protein isolate
(El-Adawy, 2000).
Succinylation causing increasing negative charge.
Lawal et al, (2005) noted that increasing negative charge of
succinylated protein would especially promote protein-
protein interaction which facilitate improved foaming
capacity. Shilpashree et al, (2015) reported that increase in
foam capacity of protein could be due to significantly
increased water holding capacity of protein. According to
Bora (2002) that, increase in water holding capacity is due
to unfolding of protein due to electrostatic repulsion
between the added carboxyl groups and the neighbouring
native carboxyl groups, exposing buried amino acid
residues and making them available for interactions with
aqueous medium.
Foaming stability
The effect of succinylation on foam stability of
gelatin is shown in Figure 2. The foam stability of
decreased constantly with time in all treatments. However,
the foam stability of control gelatin was slightly higher
compared to the succinylated gelatin samples. Foam
stability is reduced with succinylation because of negative
charges imparted during modification causing the protein
molecule to unfold.
Modification lead to increased net charge density
which prevent protein-protein interaction in foam lamellae,
ISSN: 2338-1345 Vol. (5). 2-6 2017 Journal online http://journal.bakrie.ac.id/index.php/APJSAFE
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hence causing foam destabilization and poor stability
(Cheftel et al., 1985). Similar result was found for oat
protein isolate (Mirmoghtadaie et al., 2009) which
explained that decrease in foaming stability was due to
excessive increase in charge reduce protein-protein
interaction, hence prevent the formation of an elastic film
at the air-liquid interface.
Figure 2. Foaming stability of succinylated gelatin
The unfolding and dissociate protein might exposed
more hydrophilic groups than hydrophobic, thereby
increasing hydrophilic binding site (El-Adawy, 2000).
Protein with low hydrophobicity showed poor stability.
According to Townsend and Nakai (1983), hydrophobicity
of protein are associated with good balance of both
hydrophobic and hydrophilic group necessary for effective
stabilization of air bubbles. Foam stability is directly
affected by protein concentration which will influence the
thickness, mechanical strength and cohesiveness of film
(Zayas, 1997).
CONCLUSIONS
Gelatins were succinylated by adding different
concentration of succinic anhydride based on the sample
weight. From the result, it was shown that extent of
succinylation increased as concentration increased. Also
result showed that succinylation was able to improve the
Bloom strength of gelatin but the improvement declined at
concentration beyond 8.10% succinylated gelatin level.
The addition of succinic anhydride in gelatin influenced the
foaming properties, whereby foaming capacity increased at
increasing level of modification. However, foaming
stability of succinylated gelatin decreased with time.
ACKNOWLEDGEMENT
The authors acknowledge with gratitude the support
given by Universiti Sains Malaysia,and Universiti Sultan
Zainal Abidin to conduct reserach in the area of food
science and technology.
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The functional properties of native and succinylated lentil globulins were evaluated. Succinylation caused a shift in the isoelectric pH of native globulins from 4.5 to 3.5 and improved the solubility above pH 4.0. However, below this pH the solubility of succinylated globulins was reduced. The water absorption and the viscosity of the sucinylated globulins were increased by almost 100%, while there was a decrease in the oil absorption capacity. The extent of succinylation used in this study did not show any significant relationships to these functional properties. Emulsion activity was also increased by succinylation; being 54.1% for the native globulins, 60% for the 57.9% succinylated globulins and 62.7% for the 87.2% succinylated globulins. Similarly, the emulsion stability was also improved. Foaming capacity of the succinylated globulins was decreased slightly, while foam stability, except at pH 2.5, was considerably reduced. Native and succinylated globulins showed maximum foam stabilities at pH 3.5 and 2.5, respectively.
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The purpose of the present study was to determine the influence of protein isolation from potato juice and acetylation on the chemical composition and chosen functional properties of obtained preparations. Potato protein preparations used for the experiment were obtained by thermal coagulation and membrane technology. Preparations containing thermal coagulated (PPI) and native (PPC) protein, respectively, were subjected to the chemical modification by acetylation with the use of different doses of acetic anhydride. Changes in chemical composition (total and coagulable protein content, ash content and amino acid composition), functional properties (water holding capacity, oil holding capacity, protein solubility index, emulsification properties as well as foam capacity and stability) and extent of chemical modification were determined. The chemical composition and functional properties of obtained preparations were significantly different (p