Conclusion. It was found that this material presented characteristics similar to those reported for commonly used wall and encapsulation material, such as starch ...
Taro starch sperical aggregates as microencapsulating starch-based matrix: partial characterization Bello-Pérez, Luis Arturo1; Hoyos-Leyva, Javier Darío1,2; Gutierrez-Meraz, Felipe1 Politécnico Nacional, CEPROBI, Yautepec, Morelos, México. 2 Fundación Universitaria Agraria de Colombia, Agroindustrial engineering program, Bogotá D.C., Colombia.
INTRODUCTION
The isotherm exhibited a Type II sigmoid shape (Figure 2) that is typical of biopolymers, such as starch, gums, Opuntia sp. Mucilage, pinhao flour, semolina and farina, chitosan, among many other products. The GAB model was used to fit experimental data for different temperatures. The GAB parameters are depicted in Table 2. The MRE values were not higher than 3.0%, indicating acceptable numerical fitting.
AIMS
Spray drying process
20
20 30 40
15 10 5 0 0
0.2
0.4 0.6 0.8 Actividad de agua (aw)
1
Figure 2. Adsorption isotherms of taro starch spherical aggregates at 20, 30 nd 40 °C.
The variation of Xm with temperature can be attributed to structural changes of the surface. The parameter C reflect strong interactions between water molecules and solid surface. In the case of the spherical aggregates, the value of the parameter increased with the temperature, suggesting more stable adsorbed water molecules on the starch surface. The parameter K reflects interactions between water molecules and absorbents in the multilayers.
•Morphology of starch spherical aggregates
Table 2 shows that K presents a slight decrease with temperature, implying weaker interactions in the multilayer region. Porosity and the specificity of water molecules attraction close to hydrophilic surface sites are important factors affecting the structuration of multilayers in food matrices [3].
Table 2. GAB adsorption parameters Xm, C and K of taro starch spherical aggregates
•Chemical characteristics
T (oC)
Xm (g H2O∙100 g -1 b.s.)
C
K
EMR (%)
20
5.78 ± 0.21c
5.19 ± 0.12cd
0.82 ± 0.02a
2.94
25
6.91 ± 0.16ab
5.04 ± 0.13cd
0.78 ± 0.03a
2.91
30
7.22 ± 0.25a
5.67 ± 0.12c
0.75 ± 0.02ab
1.39
35
6.86 ± 0.14ab
7.21 ± 0.09b
0.77 ± 0.03a
1.62
40
6.77 ± 0.26b
8.14 ± 0.16a
0.77 ± 0.03a
1.45
45
7.15 ± 0.28a
7.24 ± 0.13b
0.75 ± 0.03ab
1.04
Taro corms
•Sorption and physical stability DSC DVS-Dynamic vapor sorption
-1
Reversible Heat Flow (W g )
The Tg of the starch aggregates was in range between 75 °C to 176 °C, under water excess and 0.1 aw, respectively (Figure 3.b). The Tg at 72 % RH was 89 °C, which suggest that the material retain its glassy state above 72 % RH at ambient temperature (25 °C) protecting a potential core material.
Results The aggregation of relative high quantity of starch granules formed a porous structure which could be filled by core materials (Figure 1.a). The mean size diameter of the spherical aggregates observed in the SEM micrography’s was 16 µm. The CLSM images showed that protein was located between the surface of starch granules aggregates, which suggest that protein influence positively the starch granules aggregation (Figure 1.C).
69
72
75
78
81
o
84
180
-1
Reversible Heat Flow (W g )
Temperature ( C)
c
b
Values represent the mean of three determinations ± standard error. Xm =monolayer moisture content; C= Guggenheim constant; K = correction factor. (a) Values in column with some superscript letter are not statistically different.
(a)
(b)
160
o
Taro starch spherical aggregates
Physicochemical features
a
25
Tg ( C)
Materials and methods
The aim of this study was to determine physical characteristics of taro starch spherical aggregates from microencapsulation approach.
Contenido de humedad (g ∙ 100 g-1)
1Instituto
y = 278.9x
140
-0.27
2
, R = 0.93
120 100 80
69
72
75
78
81
o
Temperature ( C) 180
84
0
10
20
30
40
50
60
70
80
Relative Humidity (%)
(b)
140
-0.27
2
o
Tg ( C)
Figure 3. Glass transition representation (a) and change of glass transition temperatura 160 as a function of environment relative humidity (b). y = 278.9x , R = 0.93
Figure 1. SEM micrographs of taro starch spherical aggregates at 1,000X (a) and 10,000X (b). C. Confocal laser light scanning 3D image of taro starch spherical aggregates.
120 Conclusion. It was found that this material presented characteristics similar to those reported 100 for commonly used wall and encapsulation material, such as starch films, chitosan, mucilage, etc. It 80is concluded that spherical aggregates from taro starch are a good alternative for encapsulation biocompounds without the incorporation of structure stabilizing agents. 0 10 of20 30 40 50 60 70 80
References
The moisture, protein, and amylose content, and starch purity (Table 1) were in range with the literature reports [1,2], however some differences may be found due to agroclimatic conditions and starch isolation conditions.
Table 1. Starch purity, moisture, protein and amylose content in taro starch spherical aggregates. Percentage (g∙100 g-1) Moisture
5.7 ± 0.2
Protein
3.7 ± 0.1
Total starch
83.3 ± 0.8
Amylose
12.9± 0.8
Values represent the mean of three determinations ± standard error.
Relative Humidity (%)
1. Hoyos-Leyva, J.D., Bello-Perez, L.A., Alvarez-Ramirez, J., Garcia-Galindo, H.S. 2018. Food Reviews International, 34(2), 148-161. 2. Gonzalez-Soto, R.A., de la Vega, B., García-Suarez, F. J., Agama-Acevedo, E., & Bello-Pérez, L. A. 2011. LWT-Food Science and Technology, 44(10), 2064-2069. 3. Beirão-Da-Costa, S., Duarte, C., Moldão-Martins, M., Beirão-Da-Costa, M.L., 2011. Journal of Food Engineering. 104, 36–42. 4. Viganó, J., Azuara, E., Telis, V. R., Beristain, C. I., Jiménez, M., & Telis-Romero, J. 2012. Thermochimica Acta, 528, 63-71.
