The anticoagulant activity of alginate sulfate depend on the molecular weight, the M/G ratio, the uronic sequencing, the seaweed species, etc.. The dissertation “Research on preparation
Trang 1MINISTRY OF EDUCATION AND TRAINING
NHA TRANG UNIVERSITY
NGUYEN VAN THANH
RESEARCH ON PREPARATION OF LOW MOLECULAR WEIGHT ALGINATE FOR USING FUNCTIONAL FOODS
IN PREVENTING BLOOD COAGULATION
SUMMARY OF THE DOCTORAL DISSERTATION
Speciality : Aquatic Products Processing Code : 9540105
KHANH HOA - 2019
Trang 2The project was completed at Nha Trang University
The scientific advisors:
1 Assoc Prof Dr Vu Ngoc Boi
2 Assoc Prof Dr Tran Thi Thanh Van
Reviewer 1: Assoc Prof Dr Ngo Đang Nghia
Reviewer 2: Assoc Prof Dr Ngo Đai Nghiep
Reviewer 3: Assoc Prof Dr Nguyen Huu Đai
The dissertation was evaluated by the Scientific Committee at Nha Trang University on
The dissertation can be found at: The National Library
The Library of Nha Trang University
Trang 3SUMMARY OF THE DOCTORAL DISSERTATION’S NEW
CONTRIBUTIONS
Dissertation topic: Research on preparation of low molecular weight alginate for using
functional food in preventing blood coagulation
2 Assoc Prof Dr Tran Thi Thanh Van
School: Nha Trang University
2) The dissertation has identified the optimal parameters for the extraction procedures for alginate has high viscosity from marine brown seaweed T ornata: solution
to Na 2 CO 3 was pH 11, the temperature was 59 o C, time was 1.5 hours Sodium alginate precipitated in concentrations of ethanol appropriate was 70% Sodium alginate from T ornata has high purity, the M/G ratio of 1.06, an average molecular weight of 648.32 kDal,
an average degree of polymerization of 1037, the polydispersity index indicator of 3.56, the process performance reached 87,93% Alginate products are produced according to the process meeting the criteria of sensory, chemistry and microorganism according to the current regulations of Ministry of Health
3) The dissertation has prepared low molecular weight alginate by hydrolysis with acid After hydrolysis products obtained: sodium guluronate fraction, sodium mannuronate fraction and fraction of sodium guluronate - mannuronate content was 49.17
± 1.21%, 38.13 ± 1.16% and 3.96 ± 1.08% of alginate weight, respectively The results
Trang 4indicated that the low molecular weight alginate has high purity An average molecular weight of sodium guluronate and sodium mannuronate of 21.661 kDa and 33.759 kDa, an average degree of polymerization of 89 and 128, the polydispersity index indicator of 1.38 and 1.49, respectively
4) The dissertation has determined the appropriate conditions for preparing for low molecular weight sodium guluronate sulfate (SGS): the conditions of the sulfonation agent reaction have been optimized: the NaHSO 3 /NaNO 2 concentration rate is 4.25/1 mol/g, the reaction temperature is 90°C and the reaction time is 90 minutes The conditions of sodium guluronate sulfate synthesis reaction were surveyed under appropriate conditions of pH =
9, the sulfonation agent/sodium guluronate concentration rate is 2/198 mol/g, the reaction temperature is 40°C and synthetic reaction time is 4 hours The dissertation has built the process of producing SGS from alginate of T ornata Since then, the process of producing SGS from sodium alginate of brown seaweed T ornata has been established Sodium guluronate sulfate has high purity, an average molecular weight of 25.408 kDa, an average degree of polymerization of 107, the polydispersity index indicator of 1.35
5) The dissertation has evaluated the anticoagulant activity of low molecular weight sodium guluronate sulfate The results have showed that sodium guluronate sulfate depend
on its an average molecular weight and contents The study results the anticoagulant activity of sodium guluronate sulfate have showed that it can extend the activated partial thromboplastin time (APTT) and the thrombin time, but it cann’t almost be able to expend the prothrombin time (PT) Sodium guluronate sulfate is not toxic to mice So it is usable for producing functional foods support anticoagulant activity in humans
The scientific advisors Ph.D Candidate
Assoc Prof Dr Vu Ngoc Boi Assoc Prof Dr Tran Thi Thanh Van Nguyen Van Thanh
Trang 5LIST OF PUBLISHED ARTICLES
1 Nguyen Van Thanh, Vu Ngoc Boi, Tran Thi Thanh Van and Nguyen Dinh Thuat
(2017), “Determination of the optimum conditions for the synthesis of polyguluronate
sunfate”, Journal of science - Aquatic products processing technology, NO 1/2017, Nha
Trang University, pp 82-90
2 Nguyen Van Thanh, Bui Van Nguyen, Nguyen Dinh Thuat, Tran Thi Thanh
Van and Vu Ngoc Boi (2017), “Optimizing the alginate extraction procedures from the
brown seawees residues Turbinaria ornata (TURNER) J AGARDH”, Can Tho University Journal of Science, 49B, Can Tho University, pp 116-121
3 Nguyen Van Thanh, Do Thi Thanh Xuan, Ngo Van Quang, Vu Ngoc Boi, Bui
Minh Ly, Tran Thi Thanh Van and Thanh Thi Thu Thuy (2014), “Structure and
antimicrobial activity of alginate from brown seaweed Turbinaria ornata”, Journal of chemistry, 52 (6A), Vietnam Academy of Science and Technology, pp 149-152
4 Do Thi Thanh Xuan, Nguyen Van Thanh, Dang Vu Luong, Bui Minh Ly, Tran
Thi Thanh Van and Thanh Thi Thu Thuy (2014), “Study on the separation and chemical
structure of alginate and its fractions from brown seaweed Turbinaria ornata (TURNER)
J AGARDH”, Journal of science and technology, 52 (5A), Vietnam Academy of Science
and Technology, pp 35
Trang 6PREFACE
1 The necessary of the dissertation
Alginate is one of the hydrocolloid compounds widely used in a wide variety of industries, especially in food, cosmetic and pharmaceutical industries In recent years, many studies in the world have shown that low molecular weight alginates show many valuable biological activities more than high molecular weight alginates such as antioxidant activity, anti-inflammatory activity, allergy resistance, anti-bacterian, anti-obesity, anti-cancer, hypertension prevention, cholesterol and blood sugar reduction, etc Alginate does not have the anticoagulant activity, but alginate sulfate (alginate were sulfated), especially low molecular weight alginate sulfate is highly compatible with blood because its structure is similar to the structure of heparin and its anticoagulant activity has been researched The anticoagulant activity of alginate sulfate depend on the molecular weight, the M/G ratio, the uronic sequencing, the seaweed species, etc Therefore, low molecular weight alginate sulfate has opened up potential applications for the pharmaceutical and functional food industries
The dissertation “Research on preparation low molecular weight alginate for using functional food in preventing blood coagulantion” from the source of the raw algae after the fucoidan extract is extracted, it is a very necessary requirement, in order to enhance the exploitation and efficient use of algae resources, complete the research on alginate of Vietnamese algae according to regulations, search direction, detect its anticoagulant activity Since then, open studies on low molecular weight alginate application for functional food production to actively support care for community health and socioeconomic development in the future
2 The purposes of the dissertation
Preparation of low molecular weight sodium alginate from brown algae in Nha Trang Bay which has anticoagulant activity as a raw material for functional food production
3 Materials and methods
3.1 Materials: Alginate from brown seaweed, collected in Nha Trang Bay, Khanh
Hoa province
3.2 The scope of research
(1) Research on the sources of brown seaweed material for current fucoidan and
Trang 7alginate production; (2) Research on optimization of alginate extraction processed from marine brown seaweed and quality equalization of alginate produced; (3) Research on preparation of low molecular weight alginate and evaluate its characteristics; (4) Research
on the production process of sodium guluronate sulfate (SGS) from alginate of T ornata
and evaluate the characteristics of SGS; (5) In vitro evaluation of anticoagulant activity
and toxicity assessment of SGS as a raw material for functional food production
4 Experimental method
Using modern analytical methods: Analysis of the content of heavy metals such as
Hg, As, Cd and Pb by atomic absorption spectrometric (AAS) - graphite furnaces (GF) – chemical modifier (CM); Determinate average molecular weight of alginate by gel permeation chromatography (GPC) at the University of Natural Sciences, National University Ho Chi Minh City; Determinate sulfate contents by Sulfate Barium Nephtlometry (using reflective light to measure the particle density in liquid); Methods for determining the structure of alginate: determinate Infrared Spectroscopy (IR) by FT-IR Bruker and Nuclear Magnetic Resonance Spectrum (NMR) measured at 70°C with D2O solvent on Bruker AVANCE 500 MHz at the Institute of Chemistry - Vietnam Academy
of Science and Technology; At the same time, the dissertation also uses mathematical methods in order to optimize the experimental process and process the collected statistical data aiming to assure highly reliable experimental results
5 The structure of the dissertation
The dissertation has 148 pages, including 3 pages of introduction, 35 pages of overview, 21 pages of research methods, 87 pages of research results, 2 pages of summary,
22 tables, 63 images, 246 references ( 27 Vietnamese documents, 219 English documents) and 52 pages of appendix
Trang 8Chapter 1 OVERVIEW 1.1 SOURCES OF THE BROWN SEAWEED IN THE WORLD AND IN VIETNAM
Around 2,060 species of brown seaweed and more than 95% of brown seaweed have originated in the sea The Fucales are the most common and economical species,
represented by the Sargassaceae, with two branch Sargassum and Turbinaria China is the
largest brown seaweed producer in the world with over 667,000 tonnes of dried seaweed per year South Korea, Japan, Norway and Chile has the brown seaweed yield about 96,000; 51,000; 40,000 and 27,000 tonnes of dried seaweed per year, respectively
Vietnam has discovered over 120 brown seaweed species Brown seaweed harvesting season is mainly from April to June every year Annual yield is between 15,000 and 35,000
tonnes of dried seaweed Among them, Sargassum seaweed species has the largest reserves
with about 68 species, harvesting yield about 10,000 tonnes of dried seaweed per year In Khanh Hoa province, more than 39 seaweed species in Sargassum genus are classified, however, they are gathering and have the largest reserves in Nha Trang Bay with over 21 common species Yield is estimated more than 4,800 tonnes of dried seaweed per year
In the cell of brown seaweed, the major components are anionic polysaccharides such
as alginate, fucoidin, fucin In particular, alginate content is the highest, up to 40% of dried seaweed weight; Fucoidan accounts for up to 8% of dried seaweed weight; Mannitol content can reach 30% of dried seaweed weight; Laminaran content can reach 30% of dried seaweed weight; The content of minerals in brown seaweed is 10 to 20 times higher than terrestrial plants, especially it is rich in calcium, potassium, phosphorus, magnesium and iodine; In addition, brown seaweed contains many other biological compounds such as pigment, vitamins, phenolic compounds, etc In general, the chemical compositions of brown seaweed vary with the seaweed species, season, weather, habitat, geographic locations, etc
In our country, brown seaweeds are mainly used for raw fucoidan production with an annual output of about 400 ÷ 800 tonnes of raw fucoidan In addition, this material is sold
as raw materials to China with low economic value or used for fertilizers, food for animals After being used for fucoidan production, the rest of seaweed is used for fertilizers or being discarded It can be seen that we have wasted the alginate resources almost intact in seaweed after fucoidan extraction Thus, the study on collecting alginate from brown seaweed after fucoidan extraction is essential, which enhances the value of brown seaweed
Trang 9resources Therefore, the dissertation will be studied on alginate collection from brown seaweed after extract fucoidan aim to increase the efficiency of using seaweed resources
in Vietnam
1.2 OVERVIEW OF ALGINATE
Alginate is a common term for salts of alginic acid, it is also an anionic polysaccharide, a straight chain copolymer formed from (1 4) glycosit bond of β-D-mannuronic acid (M) and α-L-guluronic acid (G) Alginate is extracted from brown seaweed In addition, alginate is also produced from a number of bacterial species The physical, chemical and biological properties of alginate vary with the molecular weight, viscosity and M/G ratio as well as the uronic arrangement in the polymer The solubility
of alginate depends on the type of metal salt, with metal salt has valence I then they dissolve
in water In contrast, with metal salt has valence II then they are not soluble in water There are many studies on alginate extraction technology worldwide However, it can
be seen that the study results of various seaweeds are different to the seaweed processing system, extraction system, extraction efficiency of alginate, and the cooking mode will affect the viscosity of alginate The viscosity of alginate is one of the important parameters reflecting the quality of sodium alginate obtained and affecting the alginate collection efficiency If the viscosity of low alginate means alginate short circuit When the alginate circuit structure is cuting short for the extraction process, the alginate recovery efficiency
is low The reason that the short molecular circuit alginate is difficult to precipitate by alcohol The extraction efficiency and viscosity of alginate are closely related in the process
of extracting alginate from brown algae In Vietnam, the number of studies on alginate extraction technology is rather rare, they have not been paid much attention At now, there haven’t been any alginate production companies All alginate products of the market are mainly imported from other countries
The research on alginate extraction from brown seaweed residues of the fucoidan production process was studied in the country from 2008 to 2010 by Nha Trang Research and Applied Technology Institute However, there are some following limitations: (1) The seaweed residues extracted from fucoidan are dried before the alginate extraction This process is not necessary because it will lead to costly energy, extraction solvent, while seaweed residue can be used immediately for alginate extraction (2) The use of formol discolors seaweed residues within 24 hours prior to alginate extraction, which will have significant effects on health and environmental sanitation, as well as on viscosity, alginate
Trang 10molecular weight (3) The obtained product is the calcium alginate which is insoluble in water It is also quite complicated to shift into sodium alginate which is soluble in water, the production process needs more stage (4) The process of producing alginate is not concerned with the viscosity of alginate, alginate quality has not been assessed and the structural properties of alginate have not been determined yet
1.3 PREPARATION OF LOW MOLECULAR WEIGHT ALGINATE
Low molecular weight alginate can be prepared by different methods such as physical method, chemical method or method of enzyme use The physical method (commonly used
by irradiation) requires the equipment that normal laboratories do not have The method of enzyme used to hydrolyze alginate into low molecular weight alginate This method does not cause environmental pollution, the products are produced by the clean technology, so
it is easy to purify and obtain However, the method of using enzymes is still relatively new to Vietnam On the other hand, there is currently no enzyme hydrolyzed alginate in commercial form, so it is difficult to research and use enzymes in alginate hydrolysis The chemical method used for alginate hydrolysis have the advantage that the cost is not high but there are disadvantages after hydrolysis which requires product refining However, the use of chemical methods of alginate hydrolysis are easy to implement and the probability
of success is quite high, in accordance with domestic research conditions Although low molecular weight alginate is prepared by hydrolysis method (acid) which has not been extensively studied in the country, it has been extensively studied in the world
The ability to apply low molecular weight alginate relates to the modulation method The results of the literature review show that low molecular weight alginate prepared by the irradiation method is mainly used in agricultural production (plants, livestock), there aren’t researches applied in food production field Meanwhile, low molecular weight alginates prepared by chemical methods and using hydrolysis enzymes have been studied and applied for food, cosmetics and medicine Therefore, to prepare low molecular weight alginate as a raw material for functional food production, the dissertation aims to select the alginate hydrolysis method by acid agent
1.4 THE APPLICATIONS OF ALGINATE AND LOW MOLECULAR WEIGHT ALGINATE
Alginate is a biopolymer considered as a new material, it is widely used in various industries The potential for alginate application for the country as well as in the world is very great, especially in food, cosmetic and pharmaceutical field The applicability of
Trang 11alginate is relatively large, not only in high molecular weight but also in low molecular weight alginate With low molecular weight alginates, it has shown many valuable
biological activities and is completely applicable to functional foods and medicine
Up to now, in Vietnam, there has not been any scientific research published on low molecular weight alginate research with anticoagulant activity as raw material for functional food production Based on the results of the literature review, it is highly feasible
to study the production of low molecular weight alginate from our brown seaweed resources Therefore, the orientation of research on low molecular weight alginate with human activity to support blood coagulation is a new study and promising field
1.5 THE BLOOD CLOT PROCESS AND ANTICOAGULANT ACTIVITY OF ALGINATE
Normally, in the blood and in the tissues, there are blood coagulants and anticoagulants, but the blood coagulants exist in the form of precursors, which are not active When the blood coagulant factors are activated, chain reactions that cause the blood
to coagulate will be promoted Blood coagulation can be triggered by endogenous pathway
by contact of the blood with the negative surface, or by the exogenous pathway, due to the interference of organizational elements Both pathways lead to the activation of factor X into Xa, which change prothrombin into thrombin This assists to change fibrinogen into fibrin Fibrin is like a net containing platelets that cause blood clots
Alginate has no anti-coagulant activity but the alginate sulfate derivative (sulfated alginate) is similar in structure and characteristics to the anticoagulant produced in hepatocytes When being sulfated, low molecular weight alginate will have anti-coagulant activity However, the anticoagulant activity of low molecular weight alginate depends on the average molecular weight and its concentration Studies in the world have shown that alginate sulfate has a major effect on prolonging Activated Partial Thromhoplastin Time (APTT) and Thrombin Time (TT) and has little effect on prolonging Prothrombin Time (PT)
Trang 12Chapter 2 MATERIALS AND METHODS 2.1 MATERIALS
Brown seaweed material composes two species belong to branch of Sargassum C Agardh 1821 (S mcclurei Setchell and S polycystum C Agardh) and one species belong
to branch of Turbinaria Lamouroux 1828 (T ornata (Turner) J Agardh) Sampling
locations: in Hon Tre, Hon Rua and Bai Nam in Nha Trang, Khanh Hoa
We first collected fresh seaweed samples of each species When harvesting, we used the sickle cut to the roots of seaweed, washed the seaweed residues with seawater Later, the seaweed was transported to the laboratory of the Nha Trang Institute for Research and Applied Technology In the laboratory, seaweeds are dried by the freeze drying method at
a temperature of 450C, wind speed of 2 m/s until the seaweed reaches a moisture content
of 14-15%, then ending the drying process Then dried seaweeds were wrapped in vacuum packaging PA and stored at normal temperature, high temperature, cool to use as raw materials during the study
Mice: guinea pig (Cavia porcellus), average weight from 300 to 350g, there are 80
mice for study
2.2 METHODS
2.2.1 Diagram of access to research contents: presented in Figure 2.1
2.2.2 The analysis methods
+ Determining the raw fucoidan content: According to the method of Usov et al (2001); Determining alginate and alginic acid content: According to the method of Haug
et al (1968); Determining the humidity according to TCVN 4326 - 2001; Determining the raw protein content according to TCVN 3705 - 1990; Determining the raw fat content according to TCVN 3703 - 1990; Determining the ash content according to TCVN 5611 - 1991; Determining the content of heavy metals Hg, As, Cd and Pb by atomic absorption spectrophotometric - graphite furnace - chemical modifier (CM-GF-AAS) according to AOAC999.11:2011
+ Determining the microbial content by colony counting method: determining the total aerobic bacteria according to TCVN 4884 - 2005; determining the total number of
yeast spores, molds according to TCVN 4993 - 1989; determining Coliforms according to TCVN 4882: 2007; determining Salmonella according to TCVN 4829:2005
Trang 13Figure 2.1 Diagram of access to research contents
Brown seaweed
Research on the sources
of brown seaweed
material for current
fucoidan and alginate
production
determine harvesting time suitable for brown seaweed
Selection of seaweed species for research
Suggest technological process of sodium alginate
Quality equalization of low molecular weight alginate
Investigating the synthesis reaction conditions of SGS
Sodium alginate
extraction
Propose SGS production process from sodium alginate and evaluate the characteristics of SGS
* Harvesting time: from month 1/2013 ÷ 7/2013
* The highest alginate content and fucoidan content
* pH (8÷12), temperature (50 o C ÷ 80 o C), time (1÷4 giờ)
* The highest level of sodium alginate content and viscosity
* DS of SGS is highest
* Time (1÷6 hours), temperature (30 o C÷50 o C);
* Clinical observation; mass;
urine test; Hematology test and blood chemistry; surgery and microscopic observation
Trang 14+ Viscosity determination method: 1% alginate solution at 22°C is measured viscosity
on Brookfield viscometer, using spindle LV-02, speed 50 rpm
+ Determining the alginate averages molecular weight: by Gel Permeation Chromatography (GPC) method at the University of Natural Sciences, Vietnam National University Ho Chi Minh City
+ Alginate quality assessment method: According to QCVN 4-16: 2010 / Ministry of Health: "National Technical Regulation on Food Additives - Fillers"
+ Measurement of degree of substitution (DS): the DS values were determined by barium sulfate nephelometry (using reflective light to measure particle density in liquid)
according to the method of Dodgson et al (1962)
+ Structural analysis method: InfraRed (IR) spectroscopy is measured on Bruker IR; The nuclear magnetic resonance (NMR) spectroscopy is measured at a the temperature
FT-of 70°C with a D2O solvent on a 500 MHz Bruker AVANCE at the Institute of Chemistry
- Academy of Science and Technology of Vietnam; ESIMS spectroscopy is measured on Waters Xevo TQMS
+ Methods of examining anticoagulant activity of sodium guluronate sulfate (SGS): according to Fan et al (2011) The experiment was conducted at Army Medical Academy
- Military Central Hospital 108, Hanoi
+ Method for determining toxicant of sodium guluronate sulfate: by oral route, with three levels: high (2mg/day/mice), medium (1mg/day/mice) and low (0,5mg/day/mice), control group (physiological saline) Each level of study on one group of mice was assessed
20 mice and the two waves, each of the 10 mice 1st determine acute toxicity, performed immediately after the end of treatment and 2nd determine the extent of the recovery or the expression of toxic potential may occur after the end of treatment for 3 weeks
2.3 STATISTICAL ANALYSIS
Experimental data were collected by observation and statistical method Each experiment was repeated three times independently and the data were the mean of the repetitions The differences in statistics were checked by software Statgraphics Centurion XVII trial Optimizing experiments by experimental planning method Differences in the regression equation coefficients were assessed according to the t-Student standard with a significance level of α = 0.05 and a degree of freedom of 2 Validation of the regression equation by Fisher standard
Trang 15Chapter 3 RESULTS AND DISCUSSIONS 3.1 SCREENING THE BROWN SEAWEED SPECIES FOR FUCOIDAN AND SODIUM ALGINATE PRODUCTION
3.1.1 Evaluation of fucoidan and sodium alginate content in some seaweed species 3.1.1.1 Evaluation of fucoidan content in 3 seaweed species
Figure 3.1 The variation on fucoidan contents in three researched seaweed species
following the time of sampling
The results of Figure 3.1 show that the time of harvesting algae is suitable for use as
fucoidan production material for all 3 seaweed species (S mcclurei, S polycystum and T ornata) in Nha Trang bay, Khanh province is in April and May Among the 3 brown algae studied, T ornata species have higher fucoidan content than S mcclurei and S polycystum
species
3.1.1.2 Evaluation of sodium alginate content in 3 seaweed species
Figure 3.2 The variation on alginat contents in three researched seaweed species
following the time of sampling
22.67 c7
10 15 20 25 30 35 40 45
Trang 16Sodium alginate content of both S mcclurei and T ornata species was highest in April, while S polycystum species was highest in May The content of sodium alginate in
T ornata (38.93 ± 0.026%) was higher than in S mcclurei (35.44 ± 0.046%) and S polycystum (33.89 ± 0.026%) T ornata species is superior to use for production materials
of sodium alginate, therefore, it should be selected as raw materials for the production of sodium alginate
From the analysis of the content of fucoidan and sodium alginate in 3 brown algae S mcclurei, S polycystum and T ornata showed that T ornata species had higher content of fucoidan and alginate compared to S mcclurei and S polycystum species Therefore, the dissertation decided to select T ornata species to be used as fucoidan material and at the
same time to receive sodium alginate
3.1.2 Some basic chemical compositions of Turbinaria ornata
Table 3.1 Some basic chemical compositions of Turbinaria ornata
The results show that brown seaweed T ornata collected in Nha Trang Bay, Khanh
Hoa Province have relatively higher fucoidan and sodium alginate content than other seaweeds in the world Thus, it is a suitable source of material for fucoidan and sodium alginate production Therefore, the dissertation will conduct simultaneous extraction of fucoidan before studying alginate extraction to avoid wasting natural resources from brown algae In other hand, the content of heavy metals is much lower than that of other seaweeds
in the world and fully meets the standards of Ministry of Health This result shows that the
Trang 17dissertation can use the T ornata species collected in Nha Trang bay, Khanh Hoa province
as a source of obtaning both fucoidan and sodium alginate
3.2 RESEARCH ON OPTIMIZING THE ALGINATE EXTRACTION
STAGE FROM TURBINARIA ORNATA
* Optimizing to maximize the sodium alginate content: The optimum conditions for
alginate extraction to obtain the highest alginate content are: the alkaline solution to pH = 10.7, the extraction temperature 68oC and time 2.7 hours At this point, the extracted
alginate content is 37.379 ± 0.129% of dried seaweed weight
* Optimizing to maximize the viscosity of sodium alginate: The optimum
conditions for the alginate extraction process to obtain the highest viscosity alginate are: the alkaline solution pH = 11, the temperature 57.6°C and time 1.5 hours At that condition,
the viscosity of alginate reaches 720 ± 5,508 cP
* Optimizing to achieve simultaneously the highest level of sodium alginate content and viscosity
The optimum conditions for alginate extraction from T ornata in order to achieve
simultaneously the two highest levels of alginate content and viscosity are: Na2CO3
solution with pH = 11; extraction temperature 59oC; extraction time 1.5 hours With these
conditions, the alginate content extracted from the residues of brown seaweed T ornata is
34.231 ± 0.21% of dried seaweed weight, alginate production process performance reached
87.93% The viscosity of alginate extracted from the residues of brown seaweed T ornata
is 734 ± 6,245 cP, it should be classified into relatively high viscosity alginate and should
be used for food and pharmaceutical industry
3.3 RESEARCH ON EXTRACTING SODIUM ALGINATE FROM THE RESIDUES OF MARINE BROWN SEAWEED AND QUALITY EQUALIZATION
OF SODIUM ALGINATE
3.3.1 Deteminating the ethanol contents for precipitable alginate
Ethanol content 70% is an appropriate content used for precipitating so as to obtain
sodium alginate from T ornata
Trang 18Figure 3.3 The effect of ethanol content on sodium alginate content
3.3.2 Suggest technological process of sodium alginate extraction from T Ornata
* Explaining the process:
+ Treatment: brown seaweed raw material impurities are chopped (0.5 ÷ 1 cm) and
then treat with solvent mixture (Ethanol 96%/Chloroform/H2O = 89/1/10 (v/v)) with ratio w/v = 1/10 from 10 to 15 days Brown seaweed is washed three times with water RO with pH- neutral (about 6.5) and then dried
+ Extract fucoidan: brown seaweed is extracted 3 times with HCl 0.1 N solution
(pH 2 ÷ 2.5), the ratio of seaweed/solution is 1/20 (w/v), the temperature extraction is 60°C
in 2 hours for each extraction The filtrate obtained fucoidan is filtered through a filtering cloth The residue of brown seaweed is recovered to extract alginate
+ Washing: seaweed residue is washed three times with water with pH- neutral and
then dried
+ Extract alginate: preparing Na2CO3 solution to pH = 11, the volume of the alkaline solution is 25 times higher than dried seaweed weight The extraction process is carried out at temperature is 59°C within 1.5 hours
+ Filtering: after finishing the extraction, a crude filtration is carried out through
many filter sieves from small size to large size to recover the extract The seaweed residues are stirred in a clean water solution at 55 ÷ 60°C to recover the extract that remains on the seaweed residues and equipments
0 5 10 15 20 25 30 35 40