Scholarly article on topic 'Encapsulation of Gluten'

Encapsulation of Gluten Academic research paper on "Agriculture, forestry, and fisheries"

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Procedia Chemistry
OECD Field of science
{gluten / encapsulation / maltodextrin / "spray drying."}

Abstract of research paper on Agriculture, forestry, and fisheries, author of scientific article — Husniati, Etik Mardliyati, Nofa Mardia Ningsih Kaswati

Abstract Gluten is a protein contained in wheat which gives elasticity and tensile strength to dough. However, these properties may be lost during food processing because of the heat sensitivity of the protein. This research aims to encapsulate the gluten for retaining its function when being processed even at a high temperature. The encapsulation was examined for mixtures of maltodextrin with gum arabic or with casein by using either spray drying or oven drying. It was found that the mixture of maltodextrin with gum arabic (MD:GA) is more suitable for an encapsulating material than that with casein (MD:C), and the spray drying gives a better result in comparison with the oven drying. The optimum condition of the encapsulation was the mixture at MD:GA ratio 2:1 and the spray drying was at 170°C. The obtained gluten encapsulation shows slowly adhesiveness, uniformed particles, and easy flow criteria when dissolved in water.

Academic research paper on topic "Encapsulation of Gluten"


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Procedia Chemistry 16 (2015) 457 - 464

International Symposium on Applied Chemistry 2015 (ISAC 2015)

Encapsulation of Gluten

Husniatia* Etik Mardliyatib, Nofa Mardia Ningsih Kaswati0

a Center for Research and Standardization of Industry Bandar Lampung, Jl.. By Pass Soekarno-Hatta Km.l Rajabasa

Bandar Lampung, 35114, Indonesia bAgency for the Assessment and Application Technology, Puspiptek Serpong. Indonesia cNano Center Indonesia, Puspiptek Serpong. Indonesia


Gluten is a protein contained in wheat which gives elasticity and tensile strength to dough. However, these properties may be lost during food processing because of the heat sensitivity of the protein. This research aims to encapsulate the gluten for retaining its function when being processed even at a high temperature. The encapsulation was examined for mixtures of maltodextrin with gum arabic or with casein by using either spray drying or oven drying. It was found that the mixture of maltodextrin with gum arabic (MD:GA) is more suitable for an encapsulating material than that with casein (MD:C), and the spray drying gives a better result in comparison with the oven drying. The optimum condition of the encapsulation was the mixture at MD:GA ratio 2:1 and the spray drying was at 170 °C. The obtained gluten encapsulation shows slowly adhesiveness, uniformed particles, and easy flow criteria when dissolved in water.

© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/4.0/).


Keywords: gluten; encapsulation; maltodextrin; spray drying.

1. Introduction

Many food products in Indonesia contain wheat flour as a basic ingredient, such as noodles, breads, and snacks. However, wheat flour, which is starch-based, is an imported product in Indonesia. It is desirable to utilize much

* Corresponding author. Tel.: +6281540021444; fax: +62721771357. E-mail address:

1876-6196 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of Research Center for Chemistry, Indonesian Institute of Sciences doi: 10.1016/j .proche.2015.12.079

more local starch, so that the country may become independent from imported wheat flour. Moreover, local flour such as maize, cassava, potato, taro, and sago are easy to get and cultivate in Indonesia. There are many published studies suggesting that local flour can substitute wheat flour, even though some products which use wheat flour cannot be replaced. However, the interchange of wheat flour to local flour is expected to reduce wheat consumption and its import. So, the usage of local flour from cassava, tapioca, maize, sago, etc can be maximized.

The most important composition of wheat flour that is different from the other flour is gluten. Gluten is a heterogeneous protein that contains gliadin monomers and glutenin polymers, with composition on the same weight fraction in wheat flour1'2'3. Glutenin consists of polypeptide sub unit discrete connected by disulfide chain form weight molecule polymer4. Gluten in wheat contains more proline, glutamatic acid, and glutamine. Hydrogen interaction between glutamine and asparagines side chain is functioning on the merger of gliadin molecule and glutenin5. Gupta reported that wheat flour potency in bread making comes from the unique viscose-elastic characteristic of gluten6. The rheological characteristic of gluten has been indicated by Zaidal7 who found that gluten exhibited a strain hardening effect during extension in the bread making performance.

Furthermore, the insolubility of gluten in aqueous solutions is one of major limitations toward its extensive use in food processing8. Nonpolar amino acid residues in gluten such as proline, glutamine, and leucine may lead to this property. Moreover, low concentration of ionisable side chains such as lysine, arginine, glutamic acid, and aspartic acid also become the reason of this phenomenon. According to Pommet9, disulphide bonds play a key role in gluten aggregation mechanism, so that the sulfitolysis may modify gluten thermal reactivity. Moreover, gluten thermal reactivity can therefore be preserved, but its kinetics can be modified. In this study, we modified the particle size of gluten by encapsulating it to inhibit or even prevent gluten aggregation mechanism.

Encapsulation was originally introduced in the area of biotechnology to make production processes more efficient as the matrix around the cells allows rapid and efficient separation of producer cells and the metabolism. Such technologies were developed approximately 60 years ago, which are of significant interest to the pharmaceutical sector (especially for drug and vaccine delivery), but also are relevant to the food industry. In recent years, the food industry requires the addition of functional compounds in products. These compounds are usually highly susceptible to environmental, processing and/or gastrointestinal conditions and therefore, encapsulation has imposed an approach for effective protection of those. Functional compounds are used to control flavour, colour, texture or preservation properties.

There are no previous studies that reported the preparation of encapsulated gluten. This study becomes important for food products such as noodles using wheat. Replacing wheat flour by local starch tapioca in noodles, it is known as lethek noodles among Javanese people. From reports by Maryani10 and Kusnanda11, these noodles have shabby appearance after being cooked, with high stickiness and are easy to lose their firmness during cooking, resulting in less attractiveness for consumers. Recently, Husniati12'13 shows that the utilization of a small amount of gluten encapsulation in the process of making tapioca noodles can improve the organoleptic acceptability and lower cooking loss and elongation value.

Encapsulation may be defined as a process to entrap one substance (active agent) within another substance (wall material). The encapsulated substance, except active agent, can be called core. The substance that is encapsulating is often called coating, membrane, shell, capsule, carrier material, external phase, or matrix14. In food industries, encapsulation process can be applied for a variety of reasons. Encapsulation is a useful tool to improve the delivery of bioactive molecules (e.g. antioxidants, minerals, vitamins, phytosterols, lutein, fatty acids, lycopene) and living cells (e.g. probiotics) into foods15. In most cases, encapsulation refers to a technology in which the bioactive components are completely enveloped, covered and protected by a physical barrier, without any protrusion of the bioactive components16. Also, encapsulation has been defined as a technology of packaging solids, liquids, or gaseous materials in small capsules that release their contents at controlled rates over prolonged periods and under specific conditions17. Produced particles usually have diameters of a few nm to a few mm18. One of the most commonly used encapsulation methods is spray drying.

Spray drying is the oldest method of encapsulation in the food industry and was discovered in 193019. Factors that influence the amount of material that is coated include coating materials, emulsifiers and drying process conditions20. Encapsulation by spray drying method consists of three processes, which are preparation of emulsion, homogenization and spraying the emulsion into the chamber (atomization mass on drying). One problem that usually appears in the use of spray drying is the core material attached to the surface of the capsule wall can be

oxidized and causes flavor changes in the product19.

Therefore, the aims of this study are to investigate the best material for gluten encapsulation. By controlling the particle encapsulated gluten.

2. Materials/Method

2.1. Materials

Commercial wheat gluten was obtained from Biowanze BE-4520 SA, Belgium with protein content [Kjeldahl] 76%; maltodextrin [ALTRIN D-1012], gum arabic [269/10A], casein sodium salt from bovine milk (Sigma) as a food-grade coating materials; acetic acid [Merck], ethanol [Merck], deionise water as a solvent; Amylum Manihot [Brataco] as a filler.

solvent for gluten and to characterize the best size of gluten, it is possible to obtain stable

2.2. Pre-experiment (selection of solventfor gluten)

Gluten 0.5 gram was dissolved in 20 mL of 96% ethanol21, and gluten 0.5 gram also was dissolved in 20 mL of 5% acetic acid22 by stirring for two hours. The physical appearances of solubilitization of gluten were observed as shown in Figure 1.

Figure 1. Solubilization of gluten in (a) acetic acid and (b) ethanol.

As indicated by Figure 1, the gluten was dissolved in 5% acetic acid (Figure la), while the gluten which was added ethanol did not become solution. This is supported by the formation of ethanol suspension after mixing gluten powder and ethanol (Figure lb). The gliadin subunits of gluten are monomeric proteins, which are soluble in 70% ethanol2, while polymeric proteins of glutelins fraction of gluten are not soluble in water and ethanol but soluble in 0.05 M acetic acid23. The glutelins are made up of high molecular weight and low molecular weight subunits4. As the reason for gluten solubility in acetic acid, it was used as the solvent of gluten for further research.

Optimization of acetic acid concentration as solvent was determined from variation concentration of 0.5, 1, 2.5 and 5% acetic acid with 10% gluten. The results showed that 0.5% acetic acid was used as the solvent concentration. Optimization conditions at low concentration of acetic acid have reduced the acidity of gluten solution.

2.3. Methods

2.3.1. Encapsulation of Gluten

a. Encapsulation with maltodextrin-casein (MD:C)

Gluten of 5 gram was dissolved in 20 mL of 0.5% acetic acid, then mixed with maltodextrin and casein. The ratio of the coating ingredients was 2:1. Water was added until its volume reached 250 ml. The emulsion was then dried with spray drying technique (inlet temperature of 170°C) while homogenizing with hot plate stirrer. Storage and preparation of encapsulation materials were performed at a room temperature.

b. Encapsulation of gluten with maltodextrin-gum arabic (MD:GA spray drying method)

Gluten with a concentration of 0.8%, 1.2% and 1.6 % dissolved in 0.5% acetic acid was mixed with maltodextrin and gum arabic. The ratios of coating ingredients were 1:1, 2:1 and 5:1. Then water was added until its volume reached 250 ml for each dissolved gluten. The emulsion was then dried by spray drying (inlet temperature of 170 and 200°C) while it was homogenized with hot plate stirrer.

c. Encapsulation of gluten with maltodextrin-gum arabic (MD:GA oven method)

Preparation of emulsion of maltodextrin-gum arabic was dried by oven using filler Amylum Manihot (amprotabR). 2g of gluten was dissolved in 20 mL of 0.5% acetic acid. 1 g of AmprotabR was added slowly to gluten mixture and stirred for 1.5 hours. The solution was poured into Petri dish and dried by oven at 60 □ C for 24 hours. The same process was taken for gluten with maltodextrin and gum arabic (with 1:1 composition).

2.3.2. Analysis of gluten encapsulation

a. Water content of encapsulated gluten and flow rate of gluten solution

Analysis of water content in encapsulated gluten was carried out by Karl-Fischer Moisture Titrator MKS-520. A sample was placed in a sample tube and then the numerical of water content of dry gluten will be displayed on screen.

Flow rates of gluten solutions were measured by glass funnel method (not free way). In this method, 1 gram of gluten was placed on a funnel and vibrated with spatula (constant). The sample drop on the prepared paper was below. Then, the height and diameter of sample were measured to get the flow rate of gluten.

b. Observation of morphology of gluten encapsulation by XRD dan SEM

Morphology of encapsulated gluten was observed by XRD (X- Ray Diffraction, Rigaku Mini Flex 600) and SEM (Scanning Electron Microscope, JEOL-JSM 6510 AL). XRD was to identify gluten phase and SEM was to observe the surface and morphology of gluten.

3. Result and Discussion

3.1. Comparison of encapsulation methods

Data for comparison of three encapsulation methods showed at Table 1.

Table 1. Comparison of three encapsulation methods

Gluten Method A Method B Method C

Encapsulation Product MD:C (spray drying method) MD:GA (spray drying method) MD:GA (Oven method)

Yield (%) can not be calculated 30.1529 not determined

Color White Yellowish brown

Appearance Powder Powder agglomeration

Adhesiveness Fast Slow -

Product from method A (MD:C coating) was so sticky in spray drying chamber; much encapsulated powder was left in the spray drying chamber and resulted in the yield from product of method A cannot be counted. The coating material with MD:GA (method B) was more effective in protecting the gluten than the coating material with MD:C (method A). It showed that different materials of coating gave different results on product. The drying methods, which were spray drying (method A and B) and oven (method C) also gave different results on product. Method C gave a caramel effect to the product, but it did not give the effect to product from method B.

Product from method A was white in color, has an unstable appearance, sticky, easy to agglomerate, and low yield so that it cannot be calculated. Product from method C was caramel-colored and tend to agglomerate at once. Therefore the selected method was B, because the product gave maximum yield, powder, yellowish color, and stable in slow adhesiveness.

Gluten encapsulation by spray drying method give a good quality in comparison with the oven drying. Spray-drying is the most widely used encapsulation method in the food industry. It is also commonly used by many researchers for preparation of dry and stable food17. Maltodextrin and gum arabic have also been widely used as coating materials17. Krishnan24 have also been conducting research to encapsulate oleoresin cardamom using gum arabic, maltodextrin and modified starch which are commercially available.

Gum arabic is compatible with proteins, carbohydrates, and modified starches18. Research from Meer and McNamee showed that gum arabic was used as a fixative in the spray-drying of flavors; it forms a thin and impenetrable film around the flavor particle that would be protected from oxidation and evaporation by absorbing the moisture of air18.

3.2. Process of gluten encapsulation with maltodextrin-gum arabic (Spray drying).

Gluten encapsulation was optimized by two better conditions: First, composition of 0.8% gluten with MD-GA on ratio 1:1 at temperature 170° C; second, composition of 1.2% gluten with MD-GA on ratio 2:1 at temperature 200 °C. Both conditions generated gluten encapsulation which is more stable than the other conditions. Nevertheless, inlet temperature is preferably lower. The result of Figure 2 and 3 showed that gluten encapsulation with MD-GA at a 1:1 ratio is less than 10 % of water activity, flow rate with low angle at 25-30° 25, and lower inlet temperature has been selected for the next experiment because it avoids microbe contamination, is easy to flow and prevents protein degradation26.

The selection of microencapsulation method and coating materials are interdependent27. Ideal coating material should exhibit characteristics of stable emulsion and homogenized with the active material at a certain ratio26. However, the microencapsulation processes is commonly used in spray-drying at a high-temperature so that the lower inlet temperature is more preferable for preventing protein degradation26.

35 ¥(*)

■ Water Content

■ Flow rate

Day To O 1 8 15 31 39 46

Figure 2. Result data of 1.2% gluten stability, MD:GA=2:1, Ti 200 °C

Day To 0 7 14 21

Figure 3. Result data ofO. 8% gluten stability, MD:GA=1:1, Ti 170 0C 3.3. Characterization of morphology on gluten encapsulation by XRD and SEM

X-Ray diffraction (XRD) is an analytical technique which is approximate for testing solid compound crystal, such as ceramics, metal of electronic material, organic compounds and polymers. The materials form could be powder, single crystal, multilayer thin-film, sheet, fiber, or irregular material28. The results of XRD analysis on encapsulated gluten are shown in Figure 4. There is a reason why the coating material (MD-GA) is done at different ratios of 1: 1 and 2:1. The composition of the coating material is selected so that the process is more economical by using MD more. The result of XRD showed that crystalin shape on gluten with the ratio 2:1 (black line) and 1:1 (red line) were amorphous. This result was supported by the data from XRD result on free gluten which had blue colour. Free gluten had amorphous structure; every spectrum did not show the peaks that the shape was not crystal (sharp peak).


Figure 4. Characterization of morphology on gluten encapsulation by XRD

The results of analysis of the scanning electron micrograph of encapsulation gluten using maltodextrin and gum arabic (1: 1) and (2: 1) with a spray drying method are shown in Figure 5 and 6. The gluten encapsulation yields are generally round in shape with a cracked surface, not contained flat or deep creases on its surface. The size of the encapsulated gluten was obtained, which was l|j.m. As the observations done by Charpentier29, the microcapsules from gum arabic, gelatin and starch dissolved had a ball-like shape that has been dehydrated. Lian30 stated that the shape of the crack is likely to facilitate the release of heat from inside particles after drying and less heat injury for material coated.

Figure 5. SEM analysis result of encapsulated gluten 1:1.

Figure 6. SEM analysis result of encapsulated gluten 2:1

4. Conclusions

Gluten encapsulation is a safe technology for the preparation of consumed food additives. Its presence can increase the elasticity and tensile strength of gluten-free flours dough. The optimized encapsulation was obtained from 0.8% gluten in 0.5% acetic acid coating with a mixture ratio of 2:1 of maltodextrin and gum arabic using spray drying method at 170 °C. This gives characteristics of stable, slow adhesiveness, uniformed particles, and easy to flow.


This project was funded by Center for Research and Standardization of Industry Bandar Lampung through DIPA in Fiscal Year 2013. The financial support is gratefully acknowledged. The researchers would like to thank Nanotech Indonesia Company for research collaboration in the manufacture of gluten encapsulation, and Tanaka Ryohei, Ph.D (silver expert) for his assistance and feedback.


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