2. Materials and Methods
2.1. Materials
The main raw material for this study was cassava (Manihot esculenta), sourced from the Hawassa Agricultural Research Center (HARC) in Ethiopia. Situated at an altitude of 1700 meters, HARC provided cassava samples, which were carefully processed through washing, manual peeling, and thorough rinsing with distilled water to remove debris. These steps ensured the cassava roots were clean and prepared for subsequent starch extraction, forming the basis for film production. A variety of chemicals and reagents supported the cassava starch analysis, focusing on measuring the film's physical and chemical properties. Potassium hydroxide (KOH) and sodium hydroxide (NaOH) were used for determining crude fiber, fat, and amylose content. Additional chemicals, such as boric acid, hydrochloric acid, sulfuric acid, potassium sulfate, and copper sulfate, were essential for assessing crude protein, fiber, and nitrogen content. Other reagents, including 99% ethanol, glacial acetic acid, iodine, and potassium iodide, aided in evaluating amylose and amylopectin. Glycerol served as a plasticizer in the film-forming process, sunflower oil was utilized for oil absorption tests, and sodium chloride was applied in water vapor transmission rate (WVTR) experiments. The study employed a range of instruments for experimental analysis, including an oven (Thermostatic drier), muffle furnace, and texture analyzer instrument facilitated measurements of chemical properties, film thickness, and material strength.
2.2. Methods
2.2.1. Extraction of Cassava Starch
Cassava starch was extracted according to the method defined by Chisenga et al.
[8] | S. M. Chisenga, T. S. Workneh, G. Bultosa, and M. Laing, “Characterization of physicochemical properties of starches from improved cassava varieties grown in Zambia,” vol. 4, pp. 939–966, 2019, https://doi.org/10.3934/agrfood.2019.4.939 |
[8]
with slight modifications. The cassava roots were taken to the laboratory immediately after harvesting. They were thoroughly cleaned, peeled, chopped into small pieces, and then blended. The resulting pulp was combined with clean water in a 1:10 ratio, meaning the volume of water was ten times greater than that of the pulp. This mixture was well-stirred and then filtered through cloth. The liquid obtained was allowed to settle, and the clear liquid on top was carefully poured off, while the remaining residue was rinsed. The starch was rinsed with distilled water and, after further decanting, left to dry on aluminum trays in sunlight for 48 hours at room temperature. This process ensures the starch reaches its minimum moisture content. Once dried, it was stored in airtight plastic containers at room temperature. Additionally, samples from both types were preserved at room temperature for future analysis.
2.2.2. Characterization of Starch
(i). Moisture Content
Moisture content in both verities of cassava starch was measured based on methods developed by Nuwamanya et al.
[6] | E. Nuwamanya, Y. Baguma, N. Emmambux, and J. Taylor, “Physicochemical and functional characteristics of cassava starch in Ugandan varieties and their progenies,” J. Plant Breed. Crop Sci., vol. 2, no. 1, pp. 1–11, 2010. |
[6]
with minor modification. In this procedure, 3-gram samples of dried cassava starch were weighed and heated in an oven at 130°C for 3 hours. The moisture content was determined by calculating the percentage weight loss relative to the original wet weight of the sample. The moisture content was then calculated using the following Equation (
1).
where Wi is the sample's initial weight prior to drying, MC is its moisture content, and Wf is its final weight following drying.
(ii). Total Ash Content
To determine the total ash content, we used a modified version of the method described by Chisenga et al.
[8] | S. M. Chisenga, T. S. Workneh, G. Bultosa, and M. Laing, “Characterization of physicochemical properties of starches from improved cassava varieties grown in Zambia,” vol. 4, pp. 939–966, 2019, https://doi.org/10.3934/agrfood.2019.4.939 |
[8]
. Samples weighing 3 grams each were placed in crucibles and heated in a muffle furnace at 550°C for 3 hours. The percentage of total ash (dry weight basis) was calculated using Equation (
2).
(2)
where W stands for empty crucible weight in grams, W1 for crucible weight plus dry sample material, and W2 for crucible weight plus ash.
(iii). Crude Fiber Content
To determine the crude fiber content, we followed the AOAC Official Method 962.09
[9] | AOAC, “AOAC: Association of Analaytical Chemists,” vol. 1, no. Volume 1, 2000. |
[9]
. The crude fiber content was calculated by using Equation (
3).
(3)
where W1 is the weight of the dried crucible with fiber. W2 = crucible weight with ash Ws = Dry weight of the sample.
(iv). Crude Fat Content
The fat content was calculated by the method previously explained by Nielsen
. Petroleum ether was used with a Soxhlet apparatus to extract the fat from the sample. Extraction thimbles were filled with samples. The Soxhlet extraction chamber was filled with the thimbles containing the sample. Petroleum ether is used to wash the fat into the extraction flasks. After removing the extraction flasks from the extraction chamber, they are put in the drying oven along with the extraction beaker, and they are allowed to air dry for 30 minutes at 100°C overnight. After cooling in a desiccator, weigh the beaker. Finally, the fat content was calculated by using equations (
4) and (
5).
(4)
(5)
(v). Crude Protein and Nitrogen Content
To determine the crude protein content, we followed the AOAC Official Method 976.05
[9] | AOAC, “AOAC: Association of Analaytical Chemists,” vol. 1, no. Volume 1, 2000. |
[9]
. The percentage of nitrogen was calculated using Equation (
6).
(6)
Given that the molecular weight of nitrogen is 14.00, the volume of HCl in liters used until the titration endpoint is V, and the normality of HCl is usually about 0.1N, along with the molecular weight of nitrogen represented as MW
n and an acid factor of 1, the conversion of nitrogen percentage to protein percentage can be determined using Equation (
7) with the appropriate conversion factors.
(vi). Carbohydrate
According to Saleh et al.
[11] | A. Saleh, A. A. Mohamed, M. S. Alamri, S. Hussain, A. A. Qasem, and M. A. Ibraheem, “Effect of different starches on the rheological, sensory and storage attributes of non-fat set yogurt,” Foods, vol. 9, no. 1, 2020, https://doi.org/10.3390/foods9010061 |
[11]
, the method of difference was used to determine the starches' carbohydrate content. The residual will be the total carbohydrate content after the percentages of the sample's moisture, crude fiber, ash, and protein content are subtracted from 100%. Consequently, the starch samples' total carbohydrate content was calculated by Equation (
8).
(8)
(vii). Amylose and Amylopectin Content
The procedure outlined by Hassan et al.
[12] | L. G. Hassan et al., “Extraction and Characterisation of Starches from Four Varieties of Mangifera indica Seeds,” vol. 3, no. 6, pp. 16–23, 2013. |
[12]
was used. Consequently, to gelatinize the starch, a 0.10-gram sample was mixed with sodium hydroxide and ethanol and heated. Following cooling, acetic acid and iodine solution were added to dilute the mixture. Using a spectrophotometer, the absorbance at 620 nm was determined. Equations (
9) and (
10), respectively, were used to calculate the amounts of amylose and amylopectin.
(9)
(10)
(viii). Swelling Power
The techniques outlined by Hefnawy et al.
[13] | T. H. Hefnawy, L. M. M. El-maghraby, M. M. Abd-rabou, and A. Y. El-khateeb, “Modification of yellow corn starch acetylation by acetic anhydride,” vol. 20, no. 2, pp. 9125–9132, 2020. |
[13]
were used to calculate swelling power. For 30 minutes, 0.1 g samples were heated in a water bath with 10 ml of distilled water at 60°C while being constantly stirred. For fifteen minutes, the samples were centrifuged at 1600 rpm. Equation (
11) was used to weight and compute the precipitated portion.
(11)
(ix). Water Solubility
The techniques explained by Hassan et al.
[12] | L. G. Hassan et al., “Extraction and Characterisation of Starches from Four Varieties of Mangifera indica Seeds,” vol. 3, no. 6, pp. 16–23, 2013. |
[12]
were used to determine water solubility. The 0.5 g samples were heated for 30 minutes without mixing in a 10 ml distilled water bath at 60°C. For ten minutes, the samples were centrifuged at 1600 rpm. Five milliliters of the supernatant were separated, dried, weighed, and computed using the Equation (
12).
(12)
(x). Water Absorption Capacity
The approach outlined by El-Safy
was used to determine the starch's capacity to absorb water. One gram of the starch sample was combined with 10 milliliters of distilled water in a beaker. The mixture was stirred for five minutes using a magnetic stirrer. Following this, the suspension was subjected to centrifugation at 3600 rpm for 30 minutes. The volume of the resulting supernatant was measured using a 10-milliliter graduated cylinder. The water absorption was determined by subtracting the supernatant volume from the initial volume of water added.
2.2.3. Oil Absorption Capacity of Starch
The starch samples' ability to absorb oil was assessed using the techniques previously detailed by Eltayeb et al.
[15] | A. R. S. M. Eltayeb, A. O. Ali, and R. Haron, “The chemical composition of pigeon pea (Cajanus cajana) seed and functional properties of protein isolate,” Pakistan Journal of Nutrition, vol. 9, no. 11. pp. 1069–1073, 2010. https://doi.org/10.3923/pjn.2010.1069.1073 |
[15]
. Thus, to measure oil absorption, 10 milliliters of sunflower oil were mixed with 1 gram of the sample and stirred for 5 minutes. The mixture was then centrifuged to separate the oil. The remaining oil volume was measured, and the difference between the initial and final oil volumes was used to calculate the oil absorption capacity in milliliters of oil per gram of starch.
2.2.4. Pasting Properties of Starch
The pasting properties of starches were evaluated using a Rapid Visco Analyzer (RVA), following the method described by Ikegwu et al.
[16] | O. J. Ikegwu, V. N. Nwobasi, M. O. Odoh, and N. U. Oledinma, “Evaluation of the pasting and some functional properties of starch isolated from some improved cassava varieties in Nigeria,” Electron. J. Environ. Agric. Food Chem., vol. 8, no. 8, pp. 657–665, 2009, https://doi.org/10.5897/AJB09.161 |
[16]
with slight modifications. Consequently, 2 g of the samples and 25 g of distilled water were combined to create a mixture. After adjusting the starches' starting moisture content, the time-temperature profile was set up to keep the system at 50°C for one minute and heat it from 50 to 95°C in three minutes and forty-two seconds. Following three minutes and thirty seconds at 95°C, the sample was cooled to 50°C for four minutes and forty-eight seconds, and it was then maintained at that temperature for two minutes. The pasting profile was used to read the peak viscosity, trough, breakdown, final viscosity, setback, peak duration, and pasting temperature with the aid of the thermocline for Windows software.
2.3. Development of Packaging Film
Packaging films were prepared using a casting technique, based on the methodology outlined by Adamu et al.
with some modifications. This method involved mixing 5 g of starch with 70 ml of water and 40 g of glycerol for every 100 g of starch to make film-forming solutions (FFS). At room temperature, this mixture was constantly swirled for ten minutes. To create a homogenous, bubble-free filmogenic solution, the resultant suspension was then heated on a hot plate from room temperature to around 70°C while being agitated. To create transparent and flexible films, the FFS was put into petri dishes and dried for 24 hours at 50°C in an oven (700 LT, Italy). The films were gently removed from the petri dishes and ready for additional characterization after being allowed to cool for two days.
2.4. Characterization of the Packaging Film
2.4.1. Moisture Content
The technique outlined by Costa et al.
[18] | M. J. Costa, M. J. Costa, M. A. Cerqueira, H. A. Ruiz, and C. Fougnies, “Effect on physicochemical properties Use of wheat bran arabinoxylans in chitosan-based films : Effect on physicochemical properties,” Ind. Crop. Prod., vol. 66, no. April, pp. 305–311, 2015, https://doi.org/10.1016/j.indcrop.2015.01.003 |
[18]
was used to determine the films' moisture content (MC). Approximately 50 mg of film will be dried using this procedure for 24 hours at 105°C (until the equilibrium weight). Equation (
13) can be used to determine the sample's weight loss and moisture content.
(13)
where Mi and Mf are the masses of the original and dried samples, respectively, and Mi-Mf is the weight loss of the samples.
2.4.2. Film Thickness
The thickness of the film was measured with an electronic digital micrometer (Mitutoyo Co., Japan). A calibrated digital micrometer was used to measure the dry film thicknesses with a precision of 0.01 mm. The final thickness of the film is calculated using the mean thickness value, which was obtained from random measurements taken at five different film positions.
2.4.3. Tensile Strength and Percentage Elongation at Break
The elongation at break (EB) and tensile strength (TS) of edible films were measured using a texture analyzer (TA Plus) following the ASTM D882-02 standard protocol. Film samples were cut into rectangular strips measuring 100 mm in length and 15 mm in width. During testing, the strips were clamped between grips with an initial separation of 50 mm, and force-deformation data was recorded as the samples were stretched at a speed of 10 mm/min. The thickness and width of the film samples were manually input into the connected computer system. The analyzer's software, pre-installed by the manufacturer, automatically calculated the TS and EB values. Young's modulus was derived from the strain-stress curves. Each type of starch film was tested five times per specimen from two different films, and the most accurate results were selected.
2.4.4. Water Solubility
Film solubility was measured using a variation of the technique outlined by Ojo Mofoluwaso Olufunmilola
[19] | A. J. S. and I. B. D. Ojo Mofoluwaso Olufunmilola, “Effects of plasticizer concentration and mushroom (pleurotus pulmonarius) flour inclusion on the sensory, mechanical and barrier properties of cassava starch based edible films,” vol. 7, no. 3, pp. 47–62, 2019. |
[19]
. To determine the dry film mass, the film samples are precisely weighed after being cut into 4.0 cm
2 square pieces. The films are kept at room temperature in test beakers with 50 milliliters of distilled water for twenty-four hours while being slowly stirred mechanically with a shaker. After being filtered out of the water, the samples are dried in an electrical oven set at 105 degrees Celsius for 24 hours. The water-soluble stuff was calculated as a percentage of the initial weight using the weight difference. Equation (
14) is used to determine the film's percentage solubility.
(14)
2.4.5. Color of the Film
The color of the film was examined using the Commission Internationale d'Eclairage (CIE) standard colorimetric measuring scale
[20] | L. Ballesteros-Mártinez, C. Pérez-Cervera, and R. Andrade-Pizarro, “Effect of glycerol and sorbitol concentrations on mechanical, optical, and barrier properties of sweet potato starch film,” NFS J., vol. 20, pp. 1–9, 2020, https://doi.org/10.1016/j.nfs.2020.06.002 |
[20]
. A Spectrophotometer (CM-600d) was used to measure the color of the edible films by measuring the values of L*, a*, and b*. The color of the films was evaluated following the ASTM D2244-02 standard, utilizing the D65 standard illuminant and a 10-degree viewing angle. Prior to measurement, the colorimeter was calibrated using standard black and white plates. Film samples were positioned appropriately to assess their color properties. Calibration was performed with a standard white plate (L = 94.64, a = -0.72, b = 1.7). The color difference between the samples was determined using Equation (
15).
where the white plate color standard, which serves as the film background, and the sample color parameter differ by L, a, and b.
2.4.6. Transparency of the Film
As previously mentioned by Immanuel
[21] | G. Immanuel, “Development and Performance Evaluation of Edible Film By Using Cassava Starch,” no. October, 2018. |
[21]
, the UV–Vis spectrophotometer (UVD 3200, Labomed, Inc.) was used to measure the films' transparency (in terms of opacity) at a wavelength of 600 nm. To record the absorbance spectrum, the samples were chopped into rectangular pieces and put straight into the cuvette. The empty cuvette served as the reference value for all measurements. Equation (
16) was used to determine the opacity value of each film.
In this case, Abs600 = Absorbance at 600 nm, x = Film Thickness (mm).
2.4.7. Water Vapor Transmission Rate
The water vapor transmission rate was measured using the Desiccant Method, as outlined by Syarifuddin et al.
[22] | A. Syarifuddin, Hasmiyani, A. Dirpan, and M. Mahendradatta, “Physical, mechanical, and barrier properties of sodium alginate/gelatin emulsion based-films incorporated with canola oil,” IOP Conf. Ser. Earth Environ. Sci., vol. 101, no. 1, 2017, https://doi.org/10.1088/1755-1315/101/1/012019 |
[22]
with minor modifications. Cassava starch edible films were placed on petri dishes with anhydrous calcium chloride as a desiccant. After sealing, cups were weighed and placed in a desiccator with 70% NaCl. Weights were recorded at set intervals, and the transmission rate was calculated from the weight change and film area. For every sample, the average of three measurement replications was provided. Equation (
17) was used to get the water vapor transmission rate.
where A is the film's exposed surface area (m2) and ∆m/∆t is the moisture gain weight per time (g/h).
2.4.8. Water Absorption of the Film
The water absorption (WA) test was conducted following the ASTM D-570-98 standard. Film samples were first dried at 40°C for 24 hours, cooled in a desiccator, and then cut into 2.5 x 2.5 cm squares. The samples were initially weighed in their air-dried state (W
1) and then immersed in distilled water in a petri dish at room temperature for 24 hours. After soaking, the samples were removed, gently blotted with a dry towel to remove surface water, and reweighed (W
2). The difference between the initial and final weights was determined using Equation (
18), as outlined below.
(18)
where the weights of the wet and air-dried samples are represented by W2 and W1, respectively. For each type of film, measurements were taken three times, and the average value was computed.
3. Results
3.1. Proximate Composition of Starches
The proximate composition of starches from the cassava varieties Kello and Qulle is shown in
Table 1. The results reveal important insights that can significantly influence the development of biodegradable food packaging films. Starch's functional properties, such as moisture content, ash, fat, protein, crude fiber, and total carbohydrate, directly impact its performance as a biopolymer. By understanding these characteristics, researchers can optimize the formulation of starch-based films to enhance their mechanical properties, biodegradability, and overall suitability for food packaging applications.
Moisture content is a crucial factor in the formulation of biodegradable films, as it affects the film's mechanical strength and barrier properties. The moisture levels of Kello (11.04%) and Qulle (10.6%) are lower than those reported in previous studies, indicating a potentially more stable film that could resist microbial degradation during storage. Lower moisture content can also enhance the film's shelf life, making it a suitable candidate for food packaging, where durability and protection from environmental factors are essential.
The ash content, which reflects the mineral composition of the starch, plays a role in the film's thermal and mechanical properties. Kello’s ash content (1.01%) is higher than that of Qulle (0.13%), suggesting that Kello could contribute additional mineral content to the film, potentially improving its structural integrity. Both varieties fall below the 1.5% threshold observed in previous studies, indicating they are low in minerals, which is beneficial for maintaining the uniformity and flexibility of the packaging film. This characteristic can lead to a more homogenous film structure that is less prone to brittleness.
Furthermore, the low fat and protein content in both varieties implies minimal interference with the film's formation and performance. The total carbohydrate content, particularly high in both Kello (86.45%) and Qulle (88.7%), indicates a strong potential for film formation, as carbohydrates are the primary polymers used in biodegradable packaging. The very low crude fiber content further suggests that these starches would produce smooth films that are not only aesthetically pleasing but also functional in terms of barrier properties. Generally, we can say that the proximate composition of these cassava starches highlights their potential for developing effective biodegradable food packaging films, aligning with current sustainability goals in the packaging industry.
Table 1. Proximate composition of the extracted starches.
Proximate analysis | Results from this study (%) | Previous study |
Kello | Qulle | Result (%) | Reference |
Moisture | 11.04 | 10.6 | 14.04 – 16.66 | [24] | O. Ayetigbo, S. Latif, and A. Abass, “Comparing Characteristics of Root, Flour and Starch of Biofortified Yellow-Flesh and White-Flesh Cassava Variants, and Sustainability Considerations : A Review,” pp. 1–32, 2018, https://doi.org/10.3390/su10093089 |
[24] |
Ash | 1.01 | 0.13 | <1.5 | [24] | O. Ayetigbo, S. Latif, and A. Abass, “Comparing Characteristics of Root, Flour and Starch of Biofortified Yellow-Flesh and White-Flesh Cassava Variants, and Sustainability Considerations : A Review,” pp. 1–32, 2018, https://doi.org/10.3390/su10093089 |
[24] |
Fat | 0.11 | 0.13 | 0.37 | [25] | C. E. Chinma, C. C. Ariahu, and J. S. Alakali, “Effect of temperature and relative humidity on the water vapour permeability and mechanical properties of cassava starch and soy protein concentrate based edible films,” vol. 52, no. April, pp. 2380–2386, 2015, https://doi.org/10.1007/s13197-013-1227-0 |
[25] |
Protein | 0.51 | 0.35 | 0.28 - 0.52 | [26] | M. H. A. and Hasmadi, M., Harlina, L., Jau-Shya, L., Mansoor, A. H., Jahurul and M.. Zainol, “Physicochemical and functional properties of cassava flour grown in different,” vol. 4, no. August, pp. 991–999, 2020. |
[26] |
Crude fiber | 0.01 | 0.09 | 1.17 - 2.31 | [27] | Agyepong, “Extraction of cassava (manihot esculenta cranz) starch with the aid of pectolytic enzymes from saccharomyces cerevisiae : effects of cassava varietal differences on the process.,” no. Atcc 52712, 2013. |
[27] |
Total carbohydrate | 86.45 | 88.7 | 83.92 - 85.55 | [27] | Agyepong, “Extraction of cassava (manihot esculenta cranz) starch with the aid of pectolytic enzymes from saccharomyces cerevisiae : effects of cassava varietal differences on the process.,” no. Atcc 52712, 2013. |
[27] |
3.1.1. Swelling Power of the Starch
Table 2 presents the results of the swelling power analysis for starches from two cassava varieties. The variation in swelling power between the two types could be attributed to factors such as starch granule size, the degree of interaction between crystalline and amorphous regions, and the molecular composition of amylose and amylopectin. Kello starch exhibits a greater swelling power, likely due to its lower amylose content compared to Qulle starch. The study conducted by Cornejo-ramírez et al.
[28] | Z. N. Shaimerdenov et al., “Fibre Extraction from Oilseed Flax Straw for Various Technical Applications,” Int. J. Adv. Sci. Technol., vol. 29, no. 7, pp. 1395–1407, 2020. |
[28]
, indicates that starches with a low amylose concentration are thought to have a higher swelling capacity.
Table 2. Swelling power of starches.
S/No | Samples | Swelling power (g/g) |
1 | Qulle | 5.31 |
2 | Kello | 7.46 |
The swelling power values obtained in this study align with findings from Chisenga et al. (2019), who reported that the swelling powers (g/g) of cassava starches from six different varieties ranged from 2.22 to 15.63 g/g at temperatures between 50°C and 90°C. However, the results in this study were slightly lower than those reported in earlier research. For instance, Charles et al.
[29] | A. L. Charles, Y. H. Chang, W. C. Ko, K. Sriroth, and T. C. Huang, “Influence of amylopectin structure and amylose content on the gelling properties of five cultivars of cassava starches,” J. Agric. Food Chem., vol. 53, no. 7, pp. 2717–2725, 2004, https://doi.org/10.1021/jf048376+ |
[29]
found swelling power values reaching as high as 27.2 to 42.3 g/g, while Onitilo et al.
[30] | V. F. Abioye, I. A. Adeyemi, B. A. Akinwande, P. Kulakow, and B. Maziya-Dixon, “Effect of steam cooking and storage time on the formation of resistant starch and functional properties of cassava starch,” Cogent Food Agric., vol. 3, no. 1, p. 1296401, 2017, https://doi.org/10.1080/23311932.2017.1296401 |
[30]
reported values between 9.0 and 16.9 g/g at 80°C. Additionally, the swelling power values in this research were lower than those of corn starch (4–18 g/g) and significantly lower than potato starch (42–168 g/g) as noted by Ayetigbo et al
. Swelling power is crucial for characterizing starches, reflecting their solubilization potential and non-covalent interactions, which affect the quality of cassava roots for consumption and their industrial applications
[6] | E. Nuwamanya, Y. Baguma, N. Emmambux, and J. Taylor, “Physicochemical and functional characteristics of cassava starch in Ugandan varieties and their progenies,” J. Plant Breed. Crop Sci., vol. 2, no. 1, pp. 1–11, 2010. |
[6]
.
3.1.2. Water Absorption Capacity
Table 3 shows the results for the two cassava starches' capacity to absorb water. When starch granules are combined with water, their physical characteristics and composition are known to affect their ability to absorb water
[31] | O. O. Oladunmoye, O. C. Aworh, B. Maziya‐Dixon, O. L. Erukainure, and G. N. Elemo, “Chemical and functional properties of cassava starch, durum wheat semolina flour, and their blends,” Food Sci. Nutr., vol. 2, no. 2, pp. 132–138, 2014, https://doi.org/10.1002/fsn3.83 |
[31]
. The integrity of starch in an aqueous dispersion can be determined by measuring the volume it occupies after swelling in excess water.
Table 3. Water absorption capacities of starches.
S/No | Samples | Water absorption capacity (g/g) |
1 | Qulle | 24.753 |
2 | Kello | 9.628 |
The variation in water absorption capacity (WAC) observed in the table indicates differences in hydrogen bonding among the starches, influenced by their size, shape, structural features, and water binding sites. These differences may also stem from variations in starch content or how their granules interact with water
. A higher WAC suggests a looser starch polymer structure, while a lower value indicates a more compact molecular structure
. For example, Chinma
[32] | P. Chukwuka and E. Z. E. Ida, “Determination of the Proximate Composition and Amylose Content of New Rice for Africa (NERICA) Flour,” 2020. |
[32]
reported a WAC of 18.0 g/g for cassava starch. The increased WAC in cassava starch may be linked to the abundance of polar amino acids, which facilitate water interaction. Compared to other samples, cassava starch exhibits a higher WAC, potentially due to its greater carbohydrate content
[32] | P. Chukwuka and E. Z. E. Ida, “Determination of the Proximate Composition and Amylose Content of New Rice for Africa (NERICA) Flour,” 2020. |
[32]
. While food materials often absorb water based on protein content, the low protein levels in cassava starch suggest that WAC is primarily due to the loose association of amylose and amylopectin molecules
[33] | J. Eke-ejiofor, “Functional properties of starches, physico-chemical and rheological properties of glucose syrup made from cassava and research article functional properties of starches,” no. June, 2015. |
[33]
.
3.1.3. Oil Absorption Capacity
Table 4 highlights the oil absorption capacity of starches from the two cassava varieties. Oils can interact with amylose to form complexes, which hinder starch granule swelling and complicate gelatinization. Consequently, the interaction between oil and starch is likely to influence the starch's physical properties
[31] | O. O. Oladunmoye, O. C. Aworh, B. Maziya‐Dixon, O. L. Erukainure, and G. N. Elemo, “Chemical and functional properties of cassava starch, durum wheat semolina flour, and their blends,” Food Sci. Nutr., vol. 2, no. 2, pp. 132–138, 2014, https://doi.org/10.1002/fsn3.83 |
[31]
.
Table 4. Oil absorption capacity.
S/No | Samples | Oil absorption capacity (g/g) |
1 | Qulle | 21.81 |
2 | Kello | 19.84 |
The oil absorption capacities measured in this study were lower than those reported for bean starches (2.42–3.35 g/g) by Olu-owolabi et al.
[34] | R. S. K. and P. R. R. E. NUWAMANYA, Y. BAGUMA1, “Quantification of starch physicochemical characteristics in a cassava,” vol. 16, no. 3, pp. 191–202, 2009. |
[34]
. Eke-Ejiofor
[35] | N. C. Amuzie, N. N.,*Obasi, N. E., & Unamma, “Physicochemical and Pasting Properties of Starch Extracted From Four Improved Cassava Varieties,” vol. 3, no. 1, pp. 11–22, 2017. |
[35]
found cassava starch to have an oil absorption capacity of 1.0 g/g. However, the values from this study were higher than those reported by Ezeocha and Okafor
, who noted ranges of 9.20–11.30 g/g for cassava and potato starches. Starch's oil absorption capacity indicates its emulsifying ability, enhancing mouthfeel and flavor retention. This capacity is influenced by the lipophilic properties of starch molecules and factors like amino acid content and protein structure
[37] | M. O. Onitilo, L. O. Sanni, O. B. Oyewole, and B. Maziya-Dixon, “Physicochemical and functional properties of sour starches from different cassava varieties,” Int. J. Food Prop., vol. 10, no. 3, pp. 607–620, 2007, https://doi.org/10.1080/10942910601048994 |
[37]
.
3.1.4. Water Solubility
The solubility of starch in water can be used to assess the number of interactions between starch chains in the crystalline and amorphous domains. Granular and molecular structural variations among the starches may be the cause of the variations in starch solubility shown in
Table 5.
Table 5. Water solubility of the extracted starches.
S/No | Samples | Water solubility (%) |
1 | Qulle | 36.80 |
2 | Kello | 31.52 |
Cassava starch solubility values in this study were found to be aligning with previous reports of 1.62–71.15%
[8] | S. M. Chisenga, T. S. Workneh, G. Bultosa, and M. Laing, “Characterization of physicochemical properties of starches from improved cassava varieties grown in Zambia,” vol. 4, pp. 939–966, 2019, https://doi.org/10.3934/agrfood.2019.4.939 |
[8]
. Starch solubility is positively correlated with amylose content, as higher amylose levels enhance solubility. Qulle starch, which contains more amylose than Kello starch, demonstrates greater solubility. The solubility of starch reflects the extent of intermolecular cross-linking within its granules. Compared to other tuber crops, cassava starch exhibits higher solubility, partly due to its pronounced swelling during gelatinization. This behavior is influenced by factors such as swelling power and the presence of components like phosphorus
[38] | A. Ali, T. A. Wani, I. A. Wani, and F. A. Masoodi, “Comparative study of the physico-chemical properties of rice and corn starches grown in Indian temperate climate,” J. Saudi Soc. Agric. Sci., vol. 15, no. 1, pp. 75–82, 2016, https://doi.org/10.1016/j.jssas.2014.04.002 |
[38]
.
3.1.5. Amylose and Amylopectin
Table 6 shows the amount of amylose and amylopectin in the separated cassava starches. The main causes of the variations in amylose and amylopectin content in cassava are variations in genotype or variety
[39] | B. I. Olu-owolabi, T. A. Afolabi, and K. O. Adebowale, “Pasting, Thermal, Hydration, and Functional Properties of Annealed and Heat-Moisture Treated Starch of Sword Bean (Canavalia gladiata),” vol. 2912, 2011, https://doi.org/10.1080/10942910903160331 |
[39]
. Amylose and amylopectin are the two main components of starch, a complex carbohydrate found in plants. They are both polysaccharides composed of glucose units, but they differ significantly in their structure and properties. It is classified as waxy starch when the amylose percentage is 0 –2% and as semi-waxy starch when the amylose content is 3–15%. Additionally, normal or regular starch is defined as having an amylose value of 15–35% and greater than 40%
[8] | S. M. Chisenga, T. S. Workneh, G. Bultosa, and M. Laing, “Characterization of physicochemical properties of starches from improved cassava varieties grown in Zambia,” vol. 4, pp. 939–966, 2019, https://doi.org/10.3934/agrfood.2019.4.939 |
[8]
. As a result, the cassava starch types in the current study can be categorized as regular or normal starches.
Table 6. Amylose and amylopectin content of the starches.
Parameters | Results from this study (%) | Results from previous study |
Kello | Qulle | Result | Reference |
Amylose content | 18.15±0.01 | 25.29±0.01 | 14.20 – 25.31 | [39] | B. I. Olu-owolabi, T. A. Afolabi, and K. O. Adebowale, “Pasting, Thermal, Hydration, and Functional Properties of Annealed and Heat-Moisture Treated Starch of Sword Bean (Canavalia gladiata),” vol. 2912, 2011, https://doi.org/10.1080/10942910903160331 |
[39] |
Amylopectin | 78.23±0.99 | 74.71 ±0.99 | 74.69 – 85.80 | [39] | B. I. Olu-owolabi, T. A. Afolabi, and K. O. Adebowale, “Pasting, Thermal, Hydration, and Functional Properties of Annealed and Heat-Moisture Treated Starch of Sword Bean (Canavalia gladiata),” vol. 2912, 2011, https://doi.org/10.1080/10942910903160331 |
[39] |
The amylose content in Kello starch (18.15%) was lower than that in Qulle starch (25.29%). This suggests that Kello starch may have a softer texture and lower gel strength compared to Qulle starch. Additionally, the amylopectin content in Kello starch (78.23%) was higher than that in Qulle starch (74.71%). This indicates that Kello starch may have a higher viscosity and better water-holding capacity. The results obtained in this study are generally consistent with previous reports, which have shown a wide range of amylose and amylopectin contents in different starch sources. The variation in these contents can be attributed to factors such as plant variety, growing conditions, and processing methods.
3.1.6. Pasting Behavior of the Starch
Table 7 summarizes the pasting properties of starch from two cassava varieties: Qulle and Kello. The peak viscosity (PV) for Qulle starch is 1551.0 cP, which is slightly lower than Kello's PV of 1612.0 cP, indicating that Kello starch can achieve a higher viscosity when heated. The trough viscosity (TV) for Qulle is 869.0 cP, while Kello's TV is marginally lower at 844.0 cP. This suggests that both varieties retain a similar ability to maintain viscosity, although Qulle has a slight advantage in this aspect. The breakdown viscosity (BV) shows that Qulle has a BV of 692.0 cP compared to Kello's 777.0 cP, which indicates that Qulle starch is somewhat more stable during cooking, as lower breakdown values suggest less viscosity loss upon cooling.
The final viscosity (FV) is higher for Qulle at 1345.0 cP compared to Kello's 1286.0 cP, indicating that Qulle starch can form a stronger gel upon cooling. The setback viscosity (SB) is also slightly higher for Qulle (486.0 cP) than Kello (463.0 cP), which reflects its ability to retain viscosity over time, contributing to a more desirable textural quality in applications. The pasting temperature (PT) for both varieties is similar, with Qulle at 68.40°C and Kello at 67.95°C, indicating that both starches gelatinize at comparable temperatures. The peak time for both varieties is also close, with Qulle at 5 minutes and Kello at 4.87 minutes, suggesting that they require similar times to reach peak viscosity. Generally, while both starches exhibit favorable pasting properties, Qulle starch demonstrates slightly better stability and gel strength than Kello.
Table 7. Pasting properties of starches.
Samples | PV (cP) | TV (cP) | BV (cP) | FV (cP) | SB (cP) | PT (OC) | Peak time (min) |
Qulle | 1551.0 | 869.0 | 692.0 | 1345.0 | 486.0 | 68.40 | 5.0 |
Kello | 1612.0 | 844.0 | 777.0 | 1286.0 | 463.0 | 67.95 | 4.67 |
Where: TV: Trough (minimum viscosity) (cP), PV: Peak viscosity (cP), SB: Setback (cP), FV: Final viscosity (cP), BV: Breakdown viscosity, and PT: Pasting temperature ().
3.2. Characterization of the Packaging Film
3.2.1. Moisture Content
Moisture content is a critical parameter in the characterization of films, as it directly influences their physical and mechanical properties. A higher moisture content can lead to increased flexibility and softness, but it can also compromise the film's strength and durability. Conversely, a lower moisture content can result in brittleness and cracking. In
Table 8, the Kello variety exhibits a slightly higher moisture content (11.53%) compared to the Qulle variety (10.52%). This difference might not be substantial enough to cause significant variations in the films' performance under standard conditions. However, it could become more relevant in environments with fluctuating humidity or when the films are subjected to extreme temperatures. Further analysis, such as moisture absorption and desorption studies, would be necessary to fully understand the implications of this moisture content difference on the films' long-term behavior.
Table 8. Moisture content results of the films.
S/No | Samples | Moisture content values (%) |
1 | Kello | 11.53 |
2 | Qulle | 10.52 |
3.2.2. Color of the Packaging Film
Color perception in films is a complex phenomenon influenced by various factors, including the film's composition, thickness, and the specific wavelengths of light it absorbs and reflects. When light interacts with a film, certain wavelengths are absorbed while others are transmitted or reflected. The combination of these reflected wavelengths determines the perceived color. Color plays a crucial role in packaging for several reasons. It can evoke emotions, influence consumer perceptions, and even impact product sales. For example, red can be associated with energy and excitement, while blue might convey trust and reliability. Additionally, color can be used to differentiate products and make them stand out on store shelves.
Table 9 shows significant differences in the color parameters between the Kello and Qulle varieties. The L* value, representing lightness, is considerably higher for Kello (90.14) compared to Qulle (45.02), indicating a lighter appearance. The a* and b* values, related to red-green and yellow-blue axes, respectively, also differ significantly. Kello has an a* value of -0.92, while Qulle's a* value is -0.39, suggesting a slightly more reddish hue for Kello. Similarly, Kello's b* value of 1.61 indicates a more yellowish tone compared to Qulle's -1.12. These differences in color parameters could be attributed to variations in the film's composition or manufacturing processes. Understanding these color differences is essential for packaging design, as they can impact the overall visual appeal and consumer perception of the product.
Table 9. Assessment of the color of the films.
Parameters | | Samples | |
Samples | Reference | Kello | Qulle |
L* | 90.14 | 45.020.51 | 46.520.12 |
a* | -0.92 | -0.390.10 | -0.450.02 |
b* | 1.61 | -1.120.86 | -3.170.19 |
E* | | 44.29 | 45.36 |
Chroma (C*) | | 2.68 | 4.50 |
3.2.3. Film Transparency
Transparency in packaging film refers to its ability to allow light to pass through. It's a crucial property for many packaging applications, as it can enhance product visibility, create a sense of freshness, and even influence consumer perceptions. For example, clear packaging can make products look more appealing and inviting, while opaque packaging can suggest a premium or exclusive quality.
Table 10 shows that both the Kello and Qulle varieties have relatively high transparency levels, with values of 12.72% and 13.10%, respectively. These values suggest that both films are reasonably transparent, allowing a certain amount of light to pass through.
Table 10. Transparency of the films.
S/No | Samples | Transparency (%) |
1 | Kello | 12.72 |
2 | Qulle | 13.10 |
However, a slight difference exists, with the Qulle variety exhibiting slightly higher transparency than the Kello variety. This difference might be attributed to variations in the film's composition or manufacturing process, such as the presence of additives or variations in thickness. While the difference is small, it could be relevant in applications where even subtle variations in transparency can impact the overall appearance and perceived quality of the packaged product.
Figure 1. Appearance of the developed film.
3.2.4. Film Thickness
Film thickness is a critical property that affects the physical and mechanical characteristics of packaging films. It influences factors such as strength, barrier properties, and overall performance. A thicker film can provide better protection against punctures and tears, but it may also be less flexible and more costly. Conversely, a thinner film can be more pliable and economical, but it may compromise durability and product protection.
Table 11 shows that the Kello variety has a slightly thicker average thickness of 0.12 mm compared to the Qulle variety, which measures 0.11 mm.
Table 11. Results of film thickness.
S/No | Samples | Thickness (mm) |
1 | Kello | 0.12±0.02 |
2 | Qulle | 0.11±0.03 |
While this difference might seem small, it could be significant depending on the specific application and the desired balance between strength and flexibility. For example, a thicker film might be preferable for packaging heavy or sharp products, while a thinner film could be more suitable for applications requiring a lightweight and flexible material.
Figure 2. Film thickness measurement using digital micrometer.
3.2.5. Mechanical Properties of Films
(i). Tensile Strength
Tensile strength evaluates a material's ability to withstand breaking under tension. The Kello variety has a tensile strength of 14.634 MPa, whereas the Qulle variety shows a slightly higher tensile strength of 15.952 MPa. This suggests that the Qulle variety is better able to resist tearing or breaking when subjected to pulling forces. The values for tensile strength of both samples are shown in
Table 12.
Table 12. Summary for mechanical properties of the films.
S/No | Samples | TS (MPa) | E (%) | Y (MPa) |
1 | Kello | 14.634 | 75.417 | 22.457 |
2 | Qulle | 15.952 | 60.252 | 32.351 |
(ii). Elongation (E)
Percent elongation indicates a material's ability to stretch before breaking. As it indicates in
Table 12, Kello variety has a higher percent elongation of 75.417%, meaning it can stretch more before failing. In contrast, the Qulle variety has a percent elongation of 60.252%, indicating a lower degree of elasticity.
(iii). Young’s Modulus (Y)
Young's modulus is a measure of a material's stiffness. A higher Young's modulus indicates a stiffer material, while a lower value suggests a more flexible one. As shown in
Table 12, Qulle variety has a higher Young's modulus of 32.351 MPa compared to the Kello variety's 22.457 MPa. This suggests that the Qulle variety is stiffer and less likely to deform under stress.
3.2.6. Water Absorption
The results indicate in
Table 13 shows that both Qulle and Kello films exhibited significant water absorption, with Kello demonstrating a slightly higher capacity (31.18%) compared to Qulle (28.09%). This suggests that both films are hydrophilic, meaning they have an affinity for water. The observed difference in water absorption between the two films could be attributed to factors such as the chemical composition, molecular structure, or processing conditions used in their production. Further analysis and comparison with other materials would be necessary to draw definitive conclusions about the implications of these water absorption properties for specific applications. Understanding the water absorption behavior of these films is crucial for assessing their suitability in various environments, particularly those with high humidity or direct exposure to water.
Table 13. Water absorption of the film.
S/No | Samples | Water Absorption (%) |
1 | Qulle | 28.09 |
2 | Kello | 31.18 |
3.2.7. Water Vapor Transmission Rate
The results show in
Table 14 indicates that both Kello and Qulle films exhibit relatively low water vapor transmission rates (WVTR), with Kello having a slightly lower WVTR of 0.114 g/h.m
2 compared to Qulle's 0.121 g/h.m
2. This indicates that both films offer a moderate barrier against the passage of water vapor. However, further evaluation against specific standards or requirements would be necessary to assess their performance in different applications. Factors such as the thickness, density, and chemical composition of the films likely influence their WVTR. Additionally, the environmental conditions, including temperature and humidity, can affect the rate of water vapor transmission. Understanding the WVTR of these films is important for applications where moisture control is critical, such as packaging, construction materials, or medical devices.
Table 14. Water vapor transmission rate of the film.
S/No | Variety | water vapor transmission rate WVTR (g/h.m2) |
1 | Kello | 0.114 |
2 | Qulle | 0.121 |
3.2.8. Water Solubility of the Film
The water solubility results in
Table 15 for the films made from Qulle and Kello show notable differences, with Qulle exhibiting a higher solubility of 29.15% compared to Kello's 27.28%. This variation may be attributed to differences in their chemical compositions, where Qulle may contain more hydrophilic groups, leading to greater interaction with water. Additionally, the morphological characteristics of the films—such as crystallinity—could influence how water penetrates and affects their structural integrity. In terms of applications, the higher solubility of Qulle suggests it could be advantageous for uses requiring rapid disintegration in water, like biodegradable packaging or controlled release systems. Conversely, Kello's lower solubility may make it preferable for applications needing moisture resistance, such as protective coatings. Understanding these solubility characteristics is crucial for optimizing material selection based on specific environmental and performance requirements.
Table 15. Water solubility results.
S/No | Samples | Water solubility (%) |
1 | Qulle | 29.15 |
2 | Kello | 27.28 |