Development of biodegradable casings from modified cassava starch
Elaboracion de fundas biodegradables a partir del almidón de yuca modificado
Jairo Sebastián Mendieta Bravo
Chemical Engineer, Master in Environmental
Engineering, Master in Higher Education,
University of Guayaquil,
Jairo.mendietab@ug.edu.ec
https://orcid.org/0000-0002-3148-5392
Stefanie Michelle Bonilla Bermeo
Chemical Engineer, Master in Food Processing
and Preservation, Universidad de Guayaquil,
stefanie.bonillab@ug.edu.ec
https://orcid.org/0000-0002-9391-3698
Abstract
The present work was carried out with the objective of obtaining biodegradable casings from modified
cassava starch, using celocell, glycerin, ethanol, Xanthan gum as plasticizers and mineral oil as
lubricants. Three mixtures were made; experience 1 has a composition of 20 g of modified cassava
starch with a percentage of 15% of the mixture; experience 2 has a composition of 30 g of modified
cassava starch with a percentage of 20% of the mixture and experience 3 has a composition of 40 g of
modified cassava starch with a percentage of 25% of the mixture, which were analyzed in their
physicochemical properties at laboratory level, determining the following results: experience 1 has an
elasticity of 39.2% with a biodegradability of 66.57%; experience 2 with a percentage of 6.89% of
elasticity and a biodegradability of 50.53%; experience 3 with a percentage of 8.04% of elasticity and
a biodegradability of 43.87%. In conclusion, experience 1 was determined to have better resistance to
tearing, biodegradability, thickness and performance, the biodegradable casings can be used in food
industries up to small accessories, such as related objects in the home.
Key words: Composting, Glycosides, birefringence, Colloidal water soluble, Insipid.
Resumen
El presente trabajo fue realizado con el objetivo de obtener fundas biodegradables a partir del almidón
de yuca modificado, utilizando como plastificantes celocell, glicerina, etanol, goma Xanthan y como
lubricantes aceite mineral. Se efectuaron 3 mezclas; la experiencia 1 tiene una composición de 20 g de
almidón de yuca modificado con un porcentaje del 15% de la mezcla; la experiencia 2 tiene una
composición de 30 g de almidón de yuca modificado con un porcentaje del 20% de la mezcla y la
experiencia 3 tiene una composición de 40 g de almidón de yuca modificado con un porcentaje del 25%
de la mezcla, las cuales fueron analizadas en sus propiedades fisicoquímicas a nivel de laboratorio,
Jairo.mendietab@ug.edu.ec
http://centrosuragraria.com/index.php/revista, Published by: Edwards Deming Institute,
Quito - Ecuador, October - December vol. 1. Num. 15. 2022, This work is licensed under
a Creative Commons License, Attribution-NonCommercial-ShareAlike 4.0 International.
https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es
Received July 17, 2022
Approved: August 11, 2022
92
determinando los siguientes resultados: la experiencia 1 tiene una elasticidad del 39,2% con una
biodegradabilidad del 66,57%; la experiencia 2 con un porcentaje del 6,89% de elasticidad y con una
biodegradabilidad del 50,53%; la experiencia 3 con un porcentaje del 8,04% de elasticidad y con una
biodegradabilidad del 43,87%. En conclusión, de determino la experiencia 1 resulto con mejor
resistencia al desgarro, biodegradabilidad, espesor y rendimiento, las fundas biodegradables, puede ser
utilizado en industrias alimenticias hasta accesorios pequeños, como objetos relacionados en el hogar.
Palabras clave: Compostaje, Glucosídicos, birrefringencia, Coloidal hidrosoluble, Insípida.
Introduction
Currently there is a lot of interest in the development of biodegradable plastics that are
developed by renewable sources, with similar characteristics to common plastic and capable of
replacing it without any problems. Starch is one of the raw materials that has caused curiosity
for having a good development in its characteristics due to its ease of gelling and molding
biofilms, and for having a high availability in the country taking into consideration its economic
viability.
The concern that today is manifested with the pollution of the environment has generated a
considerable increase in studies, research and development of new technologies, viable and
sustainable, following the respective standards with biodegradable plastics and strict
restrictions. As a result, research, technology and development have been employed in
industrial activities, so that there is a great contribution to the environment and to begin to take
care of our planet.
Cassava (Manihot esculenta Crantz) is considered a species of starchy roots that is cultivated
in the tropics and subtropics of the country, there are varieties of cassava types in the country
with the only difference in their physicochemical properties in relation to amylose, amylopectin
and its molecular structure. The modification of starches is carried out in order to improve
some of their characteristics such as resistance, degradation, solubility, decrease retrogradation,
among others.
According to the problem statement, plastics are very resistant to various uses or environmental
aggressions, they are lightweight compared to other materials that determine the same use and
are low cost, due to their high production on an industrial scale. The problem that plastics have
generated today is their increasing production, in which lies a low biodegradability causing a
great threat in every corner of the planet. Plastics seriously damage the aquatic ecosystem and
the other species that surround it. (Reitz et al., 2003, p. 234)
In Ecuador it is estimated that 1.5 million plastic bags are consumed each year and worldwide
500,000 million plastic bags end up in water currents and cause the death of 100,000 marine
species.
Mendieta, Bonilla 2022
October - December vol. 1. Num. 15, 2022
There is a national scope where the inadequate use of solid waste is currently a problem, among
them the basic urban sanitation services in the country, in terms of coverage, efficiency and
quality, have not been able to serve the majority of the population in a correct or satisfactory
manner. The formulation of the problem can be posed as a simple question but full of
importance in the development of the present investigation: Can biodegradable laminates be
elaborated using cassava starch? The purpose of this project is to contribute to the ecology with
the reduction of plastics, currently plastic has generated pollution and danger to the species that
inhabit the sea and land. Among its most common materials are polyethylene (PET), polyvinyl
chloride (PVC) and high and low density polyethylene, these have a long decomposition time
between 100 to 1000 years, which is why it has generated an increase in pollution in this way
producing an extreme accumulation of waste, to be more specific, a PVC material could go
through 10 generations to achieve its decomposition. Braga et al., (2018) The purpose of this
topic is to suggest an alternative to improve the problem of waste produced by plastics such as
plastic bags and many more everyday plastic products, considering the biodegradability time
of the product in which we are going to perform.
This project aims to improve or combat existing pollution due to plastic waste caused by
humans, increasingly producing the extinction of marine and terrestrial species among others
and the wearing out of the atmosphere with toxic gases thrown by plastics, This is why we are
looking for an alternative that contributes to improvements in the economic and environmental
field and this is how we will innovate an ecological product that will replace plastics by
biodegradable covers, common plastics is known by few that is one of the main pollutants
today.
As a general objective of the present research we set out: To obtain a plastic biofilm from
modified cassava starch, based on glycerin, celocell and other reagents with the respective
percentages of the mixtures, establishing temperature ranges determined in the procedure.
In order to be able to fulfill the proposed objective and the development of the research that
will lead us to satisfactory results, the following specific objectives are proposed:
• To obtain biodegradable plastic, varying the proportions of starch and plasticizers (15%;
85% - 20%; 80% - 25%; 75%), respectively.
• Determine the time of starch gelatinization for biofilm formation with respect to the
temperature variation established in the procedure ranging from seventy to eighty degrees
Celsius.
• To analyze qualitatively by observation, the characteristics of color and uniform
compactness of the different plastic biofilms formed by varying the process conditions.
• Characterize the physical properties of plastic biofilms in terms of elasticity, physical
resistance, biodegradability.
• To obtain biodegradable plastic casings by hot sealing or using thermal equipment.
94
The first plastic had its beginnings in the United States in 1860, when a prize was offered to
whoever could replace or substitute ivory to manufacture billiard bags. One of the winners was
John Hyatt, who was the inventor of celluloid, which in turn gave rise to the film industry.
By 1970, Leo Baekeland was the inventor of Bakelite, which was considered the first
thermosetting plastic; it was an insulating plastic, resistant to moderate heat, acids and water.
He was quickly recognized with this invention, and by 1930 scientists were creating the modern
polymers that currently dominate the industry. The plastic has a series of substances of similar
molecular structure and physical-chemical characteristics, these characteristics are determined
with the elasticity and flexibility during a temperature range and this is how it allows its
molding and adaptation to various forms. Plasticity is its eminent name, in which it is
considered effective in acquiring various forms, when subjected to heat directly, these give off
gases rich in dioxin, furans, carcinogenic hydrocarbons and compounds capable of suffocating
living beings. (Farias da Silva & Soares, 2021, p. 32)
Bioplastics refers to plastics made from plants or other materials in which they are not derived
from petroleum, as well as plastics derived from starch, cellulose and certain bacteria.
According to ''European Bioplastics'' these bioplastics are designated as ''polymers based on
renewable resources''.
Bioplastic is characterized by a naturally occurring plastic produced by a living organism and
biodegradable in nature, synthesized from renewable sources, so it hardly causes any further
pollution.
Déniz Mayor & Verona Martel, (2015) Bioplastics made from biodegradable material such as
corn starch, potato and cassava, are no problem for humans as it has a high energy content,
these bioplastic products marketed have 30 to 100% renewable materials. The use of renewable
biomass helps to combat climate change, unlike petroleum-derived plastic, which generates
massive greenhouse gases.
Bioplastics have disposable products that degrade in a period of one year, where the final
residue of the process is carbon dioxide, water and biomass generation, contrary to disposable
products made of common plastics that take 1,200 years to degrade, causing a cumulative
contamination of the ecosystem.
Cassava (Manihot esculenta Grantz) is a plant originated in South America is considered a root
rich in complex carbohydrates, mainly used for both human and animal consumption, ideal in
a balanced diet, is a healthy food in terms of its high content of vitamins C and B6 and minerals
such as potassium and magnesium, it is also used to obtain starch and other industrial uses.
In Ecuador, it is grown in the tropics and is located in all provinces of the country, including
the Galapagos. It is cultivated by small producers of low economic income, since it is produced
in poor soils or marginal lands. It requires little fertilizer, pesticides and water. It is a
Mendieta, Bonilla 2022
October - December vol. 1. Num. 15, 2022
subsistence crop because of its high calorie production per unit area, the amount of labor
required for cultivation, the stability of its yields and the long potential harvest period (8 to 24
months after planting). As a cheap source of calories, it is well received by rural and urban
consumers and is considered a priority product for food security.
The use of this plant is characterized by the consumption of its root, in which a large amount
of components are accumulated, among them starch is found naturally, and this happens when
the plant stores energy by assimilation of atmospheric carbon through the chlorophyll present
in the leaves. (Ortega-García et al., 2021 p. 32)
The chemical composition of cassava is basically amylase and amylopectin, 2 carbohydrates
of very different structure, these are the functional properties of starch.
The chemical composition of cassava root varies greatly in its composition and consists of 64-
72% starch and 4% sugars. It is understood that it has 71% sucrose, 13% glucose, 9% fructose
and 3% maltose, contains (1-2%) of proteins, lipids 0.5% and does not contain vitamins.
Gomez-Gamez et al., (2020) Cassava lacks proteins and fats, but it is very rich in complex
carbohydrates and a very good source of vitamin B and C. A nutritional table of cassava is
described below.
Materials and methods
In accordance with the research method, the present work is of a descriptive-experimental
type used for the elaboration process of biodegradable casings from modified cassava starch,
which will be used to establish the different percentage compositions with the purpose of
determining the correct and indicated mixture for the elaboration of the casings.
For the elaboration of biodegradable casings from modified cassava starch, the following
steps will be followed, which consist of selecting the raw material, weighing, drying, sieving,
mixing with plasticizers and other reagents and finally drying to obtain the biofilm, then
laboratory tests will be carried out for physicochemical and mechanical tests.
The raw material (cassava starch) came from the province of Manabí, the reagents and
materials were obtained from commercial houses in the city of Guayaquil and the physical and
chemical analyses were carried out in the laboratory in the city of Guayaquil.
96
Table 1. Materials and Equipment
MATERIALS AND EQUIPMENT
SUBSTANCES
Cassava starch
Distilled water
Acetic acid 5%.
Boric acid
Sodium chloride
Celocell
Glycerin
Ethanol
Sodium hydroxide 0.1 N
Mineral oil
Xanthan gum
Prepared by: Mendieta &Bonilla, 2022.
For the production of biodegradable casings from modified cassava starch, preliminary tests
were carried out to determine the best percentage of starch to use in the production of
biodegradable casings. For the preliminary tests, cassava starch was used with the following
concentrations (15%; 20%; 25% starch). The 3 mixtures plus plasticizers with different
percentages were tested.
Table 2. Percentages of Mixtures
Water: 80ml
Samples
% Cassava starch
Plasticizers
1
Prepared by: Mendieta &Bonilla, 2022.
Regarding the techniques and instruments used for the development of the research, the
experimental procedure is established in steps and sequences at laboratory level and as
instruments the number of experimental tests with their respective results, as detailed:
Cassava starch washing
The native cassava starch is washed with distilled water and mixed with a glass stirrer until a
homogeneous solution is achieved, then the aqueous mixture is passed through the centrifuge
equipment to accelerate its sedimentation with operating conditions of 2600 rpm for 15
Mendieta, Bonilla 2022
October - December vol. 1. Num. 15, 2022
minutes, this process must be repeated three times to ensure that the starch is free of
contaminants.
Then it is filtered with a vacuum pump to ensure the separation of the 2 phases and thus extract
as much water as possible, finally, it enters a tray oven at a temperature of 35 C for 12 hours
and the starch must be expanded uniformly, and finally the particle size is reduced by passing
the starch through some sieves, i.e. meshes, thus bringing it to a uniform particle size of
0.297mm.
Modification of cassava starch
The chemical modification of starch allows it to change its structure modifying its properties,
in this process it is required to keep controlled variables such as: temperature, pH, amount of
reagent, reaction time, this method is related to the substitution of the hydrogens present in the
hydroxyl groups of the amylose molecule, with these modifications achieves a product with
better characteristics increasing its resistance, permeability, compatibility with some
hydrophobic products, this method consists of performing it prior to start the process of
obtaining the biofilm, the modification is made through to the starch molecule through
acylation. (Neto et al., 2021) aetylation has been developed from the esterification of starch
with acetic acid, the type of acetylation is according to the one required i.e. (GS) the low, it is
used in the food industry for its properties of durability, consistency, texture and (GH) is the
high degree of substitution, and is used for the replacement of thermoplastics.
For the modification process, distilled water is added to hydrate the starch, then 5% acetic acid
(modifying agent) is added drop by drop to react with the starch, the pH of the mixture should
be maintained at 8-8.5 to achieve the indicated pH, the catalyst (NaOH) is added and then the
starch should be washed with water to remove excess modifying agent, centrifuged to remove
excess moisture for 10 minutes and placed in an oven at 40°C for 8 hours.
℃
for 8 hours.
Modified cassava starch drying
The acetylation process is taken to a centrifuge to remove excess moisture for 15 minutes, at a
temperature of 15
℃"
and at a speed of 2600 rpm, then it is placed in a tray oven at 35°C for a
period of 8 hours, extending the syrup to a temperature of 35°C.
℃
for a time of 8 hours
spreading the starch in the tray so that the drying is uniformly (Wichmann et al., 2022)
The gelatinization temperature of the cassava starch is 62-73
℃
and with the modified starch
it was 70-90
℃
i.e. the water retention capacity and the deformation of the material increases.
Biofilm processing
For the development of the biofilm, four premixes are prepared in order to speed up the method
of obtaining the material; the importance of these premixes is to avoid clusters during the
homogenization process.
98
First premix
The first premix is the modified starch together with distilled water, which is agitated in a
heating plate at 25
℃
at a speed of 150 rpm for 30 min.
Second premix
The second premix is the celocell together with the distilled water with agitation of 250 rpm,
to 40
℃
for 5 minutes under these conditions the whole process is maintained.
Third premix
This third premix consists of NaCl and Boric Acid, these are proceeded to weigh before and to
have it reserved until the moment to add it, its agitation is during 5 minutes at a temperature of
38°C, and then it is added to the mixture.
℃
.
Fourth premix
Then the glycerin is added to the distilled water for 5 minutes at a temperature of 40°C, then
the ethanol is added to dissolve the granules.
℃
After this, ethanol is added to dissolve the
granules, after 2 minutes a lubricant is added, which in this case is a mineral oil or it can be
stearic acid.
Fifth premix
At the moment that the polymerization reaction takes place, the fifth premix is made, which is
ethanol together with distilled water.
Sixth premix
The Xanthan gum and distilled water are added, which must be agitated for 5 minutes at a
temperature of 40°C, then 2 minutes after adding the fourth mixture the lubricating oil is
added.
℃
After 2 minutes of adding the fourth mixture, the lubricating oil is added, after having
all the premixes in optimal conditions to develop a united of all the mixtures.
Lubricant is added to the mixture as it serves as a lubricant for the biofilm, the drying of the
material should be in an oven at a maximum temperature of 110°C for 6 to 18 hours.
℃
A
release agent is used to avoid deformation of the biofilm at the time of drying. ASTM standards
indicate that the thickness of the biofilm should be less than 1-0 mm (0.04 inches) in order to
be able to perform mechanical tests.
Formulas were used as instruments for the evaluation of physical-mechanical properties such
as: sensory analysis, as well as the most important organoleptic aspects such as: texture,
flexibility, resistance.
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October - December vol. 1. Num. 15, 2022
Others such as thickness determination, moisture content determination, bioplastic yield, pH,
product temperature, tensile strength test, biodegradability determination, biofilm weight loss,
solubility.
Result
Table 3. Sensory analysis for the biofilm
Organoleptic aspects
Appearance
Texture
Flexibility
Resistance
Points
Sample 1
Translucent
Lisa
Flexible
Fort
5
Sample 2
Translucent
Lisa
Flexible
Fort
5
Sample 3
Translucent
Lisa
Unflexible
Fort
Prepared by: Mendieta & Bonilla, 2022
Table 4: Thickness of the biofilm
Bioplastic
Replicas
Thickness (mm)
Sample 1
1
0,365
0,290
0,330
0,415
Average
0,350
Sample 2
1
0,815
0,915
0,995
1,045
Average
0,94
100
Sample 3
1
1,760
1,832
1,780
1,795
Average
1,792
Prepared by: Mendieta & Bonilla, 2022
Table 5: Moisture content
Table 6: Bioplastic preparation yields
Sample 1 (g)
Sample 2 (g)
Sample 3 (g)
Starch
20,0
Sodium chloride
1,5
1,5
1,5
Celocell
2,0
2,0
2,0
Boric Acid
0,3
0,3
0,3
Bioplastic
Weights
Value (g)
Average Moisture %
Average Humidity %
Average Humidity %
Average Humidity
Sample 1
1
16,852
11,11
16,951
16,940
Sample 2
1
16,852
13,86
16,953
16,939
Sample 3
1
16,858
15,00
16,958
16,943
Mendieta, Bonilla 2022
October - December vol. 1. Num. 15, 2022
Xanthan gum
0,3
0,3
0,3
Ethanol
15,0
15,0
Glycerin
6,0
6,0
6,0
Mineral oil
3,0
3,0
3,0
Water
Initial mass
138,1
148,1
158,1
Final mass
124,08
132,06
133,78
Performance
89,85
89,17
84,62
Prepared by: Mendieta & Bonilla, 2022
Table 7: Tensile strength
Bioplastic
Test tubes
Maximum
elongation cm
Max.
elongation
Minimum Effort
cm
Minimum
Effort (%)
Sample 1
1
12,567
9,033
12,7
9,1
Sample 2
1
16,4
16,533
15,4
15,467
16,6
15,5
16,6
15,5
Sample 3
1
18,2
18,367
16,9
17,00
18,4
18,5
17,1
102
Table 8: Biodegradability
Bioplastic
Day
Weight loss
% Average weight loss
Sample 1
0
0,1815
66,57
5
0,3136
0,6321
0,7028
0,8724
0,9723
0,985
Sample 2
0
0,1334
50,53
5
0,2286
0,3251
0,4272
0,5632
0,7981
1,0618
Sample 3
0
0,1436
43,87
5
0,1652
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October - December vol. 1. Num. 15, 2022
0,2181
0,3382
0,5943
0,7482
0,86312
Table 9: Bioplastic Solubility
As a contribution to the research for the elaboration of bioplastics from modified cassava
starch, new techniques can be tested such as:
Modifying the process for obtaining the chemically modified cassava starch, by any other
process different from the acylation process, or modifying the concentrations of the substances
involved in the acylation method.
Solubility (%)
Cold distilled water
Hot distilled water
Hot drinking water
Sample 1
0,96"
4,02"
92,836
Sample 2
0,022
3,418
92,341
Sample 3
0,073
3,223
89,612
104
With 4% acetic acid within the acylation method in the process of chemically modified cassava
starch will better % yields be obtained?
We can establish the variation modification of the different samples involved in the formulation
for obtaining bioplastics, with respect to the % of cassava starch and % of plasticizers, with a
different result from those of the present research in samples 1,2,3.
With the mixture of 60% plasticizer and 15% cassava starch, will better results than the present
research be obtained in the elaboration of the bioplastic?
In order to obtain the biofilm, it is proposed to modify the control parameters such as
temperature, number of RPM in the agitation, as well as the concentrations of the reagents
involved in the different premixes.
With the modification in the concentrations of NaCl and boric acid, as well as in the time and
temperature different from the present investigation, better results will be obtained in the
elaboration of the biofilm.
Conclusions
The formulations for the elaboration of biodegradable casings of which the sensory analysis
determined the best results with sample 1, whose value with the addition of plasticizers was
75%, this statement was confirmed by the analysis carried out through the surface of responses
to the maximum stress values with a percentage of 39.12%. Sample 1 also presented the best
conditions for development due to its properties of degradation, elasticity, flexibility, with a
smooth texture and strong resistance. We can determine that the gelatinization temperature is
found in a range of 67-73
℃
The pH is a very important factor at the moment of gelatinization,
it influences in the elaboration of strong acid media, producing masses that are not very stable,
weak and damaging their structures, therefore it is necessary to modify it until it reaches a pH
of a strong base medium for the correct elaboration of the casings.
The yield of sample 1 is 89.85% due to the viscous mass that is formed, where it adheres to the
walls of the beaker producing losses in the development of the bioplastic, however, it is an
acceptable value.
0,001746𝑀𝑃𝑎
The moisture content is 11.11%, the solubility of the sample
in hot drinking water is 92.836% and in terms of biodegradation there was a loss of weight of
66.57%. With all the analyses obtained for the application of the product elaborated with
cassava starch, it should be used with a product that does not require a very high strength
resistance as indicated in the results and that should not be exposed to very high temperature
humidity, especially if it exceeds 60 minutes. The thickness obtained from sample 1 is not
within the range indicated in the standards, but this confirms that the less grams of starch used,
the better the characteristics will be.
Mendieta, Bonilla 2022
October - December vol. 1. Num. 15, 2022
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