1
Research Article
Selected physicochemical properties of starches isolated from 10 cassava varieties reveal novel industrial uses†
Gabriela Justamante Händel Schmitz1, Fernanda Helena Gonçalves PeroniOkita1, João Roberto Oliveira do Nascimento1,2, Raquel Bombarda Campanha5, Teresa Losada Valle4, Célia Maria Landi Franco3, Beatriz Rosana CordenunsiLysenko1,2,* 1
University of São Paulo, Department of Food Science and Experimental Nutrition, FCF, São Paulo, Brazil. 2 Food Research Center (FoRC–CEPID), São Paulo, Brazil 3 Universidade Estadual Paulista (UNESP), Department of Food Engineering and Technology of Food, São José do Rio Preto, SP, Brazil. 4 Agronomic Institute of the State of São Paulo, Campinas, Brazil. 5 Embrapa – Centro Nacional de Pesquisa e Agroenergia, Brasília, DF, Brazil *
Corresponding Author: Departamento de Alimentos e Nutrição Experimental, FCF, Universidade de São Paulo, Av. Lineu Prestes 580, Bloco 14, CEP 05508000, São Paulo — SP, Brazil, Tel.: +55 11 30913647; fax: +55 11 38154410.Tel: +55-11-30213647. E-mail:
[email protected] (Beatriz Rosana Cordenunsi-Lysenko)
†
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: [10.1002/star.201600272].
This article is protected by copyright. All rights reserved. Received: September 2, 2016 / Revised: December 1, 2016 / Accepted: December 1, 2016
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ABSTRACT
Although cassava is of great importance as a starch source for industrial purposes or food consumption, the evaluation of different varieties is an underinvestigated topic. Thus, in order to contribute to the identification of cassava starches more suitable for use and application in the food industry, this study aimed to analyze and compare the physicochemical properties of starches from 10 different cassava varieties of household consumption, industrial use and mixed use. In order to accomplish this goal, analyses were performed into the thermal and pasting properties, granule size and amylopectin branch chainlength distribution, amylose and phosphorus contents and scanning electron microscope (SEM) images of the starches. In addition, Principal Component Analysis (PCA) biplot was generated as one of the most useful methods to analyze multidimensional datasets with quantitative variables. Significant differences in phosphorus and amylose contents, branch-chain length distribution of amylopectin, starch granule diameter, gelatinization and retrogradation temperatures and pasting properties were obtained. Therefore, this study adds to the literature regarding the physicochemical properties of starches of these cassava varieties, contributing to improving their uses in the food industry by novel applications these starches, and adding and corroborating uses of some varieties studied.
KEYWORDS: Bitter cassava, Manihot esculenta Crantz, Physicochemical properties, Starch, Sweet cassava
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1 Introduction
Cassava (Manihot esculenta Crantz) is one of the most important sources of starch, which is extracted from the tuberous roots [1]. If properly extracted, the cassava starch has desirable characteristics for industrialized products, such as pure white color, low levels of fat and proteins, and a noncereal taste (FAO, 2016. http://faostat3.fao.org/browse/Q/QC/S). Nigeria, Thailand, Indonesia and Brazil are the largest world producers of cassava (FAO, 2016. http://faostat3.fao.org/browse/Q/QC/S). There are several varieties grown in the world but Brazil keeps the vast genetic diversity [2]. The varieties may largely differ regarding roots production, starch yield, starch content and palatability. They are classified as sweet cassavas, which have sensorial characteristics for household consumption and a low cyanogenic potential. In contrast, bitter cassavas are intended for flour and starch production due to their high cyanogenic potential [1, 3]. Therefore, there are many different cassava varieties employed for cooking or starch extraction, and the properties of the starch isolated from such a large diversity of varieties may differ. That is important because the quality of industrialized products made with cassava starch is influenced by several factors, such as the chemical composition, physicochemical properties, morphology, molecular structure, functional properties (paste viscosity and swelling) and thermal properties (gelatinization, retrogradation) of starch [4, 5, 6]. Extraction of cassava starch may be performed in backyard artisanal production units or large-scale fully-mechanized factories. Usually, the starch obtained from the tuberous roots is utilized as a native starch in food industry. In
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some cases, these starches are modified to be used in food products, or in the production of sweeteners, alcohol and monosodium glutamate [1, 7]. In the case of the wet starch from cassava, it may be fermented to produce the sour starch, a product used in industries to make cookies, breads and cakes. Furthermore, the sieved and cooked wet starch is used to prepare tapioca, a gluten-free homemade product that is quick and easy to prepare. It replaces wheat bread in the diet of individuals suffering from celiac disease, non-celiac gluten sensitivity or wheat allergy. The relevance of obtaining starches with particular properties from different cassava varieties may be exemplified by the spontaneous mutation of cassava that produces an amylose-free “waxy” starch [8]. “Waxy” starch has great advantages when used in frozen foods, because its gels have an excellent water retention capacity during defrosting, and no retrogradation or syneresis occurs during refrigeration or after the defrosting of gels. In addition, its gels are clearer and have a higher solubility and swelling power than commercial cassava starches [8]. Thus, in order to contribute to the identification of which cassava starches are more suitable for use and application in the food industry, this study aimed to analyze and compare the physicochemical properties of starch from 10 different cassava varieties of household consumption, industrial use and mixed use. Although cassava is of great importance as a starch source for industrial purposes or food consumption, the evaluation of different varieties is an under-investigated topic. Therefore, investigation into the relationship between the source varieties and the physicochemical properties of this tuberous root starch may contribute to increase its use and application in the
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food industry, which may be of special interest in the case of gluten-free or low glycemic index (GI) products intended for use by the celiac and diabetic population.
2 Materials and Methods
2.1 Materials
The tuberous roots of cassava (Manihot esculenta Crantz) landraces Cigana Preta, Vassourinha Paulista and Olho Junto, and the cultivars IAC 0601, IAC 12, IAC 13, IAC 14, IAC 576-70, IAC 90 and Caapora were obtained from the cassava germplasm bank of the Agronomic Institute of the State of São Paulo (IAC), located in the municipality of Pindorama-SP, Brazil (latitude 21°11'09''S, longitude 48°54'26''W and altitude 527 m). Some features of the 10 cassava varieties used in this study are presented in Table 1 (further information can be found in Schmitz et al. [9]). The plants of the 10 varieties were simultaneously cultivated in the same plantation under identical edaphoclimatic conditions, and all of the roots of five plants (biological replicates) of each variety were harvested at the end of one year on the same date (September 2010). Representative sections of the tuberous roots of the five individual plants of each variety were peeled, sliced, frozen in liquid N2 and pooled prior to storage at -80°C. Ethanol gradient grade for liquid chromatography
LiChrosolv®
(catalogue
number
1117274000),
Sodium
hydroxide pellets for analysis (0.02%) (catalogue number 1064691000) were obtained from Merck; Nitric acid ACS reagent (70%) (catalogue number
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438073), Ammonium metavanadate (99.996%) trace metals basis (catalogue number 573884), Ammonium molybdate tetrahydrate (99.98%) trace metals basis (catalogue number 431346), Potassium phosphate monobasic for molecular biology (≥98.0%) (catalogue number P9791), Sodium acetate anhydrous, for molecular biology (≥99%) (catalogue number S2889), isopropyl alcohol (≥99.7%) (catalogue number W292907) from Sigma-Aldrich; High purity Isoamylase from Pseudomonas sp. (catalogue number E-ISAMY) from Megazyme International Ireland Ltd.
2.2 Carbohydrate content
Starch from tuberous roots was enzymatically determined, as described by Areas and Lajolo [10]. Soluble sugars were extracted three times with 80% ethanol at 80ºC. After centrifugation, supernatants were mixed and ethanol was evaporated under vacuum using a speed-vac system. The soluble sugar content was analyzed by high pressure liquid chromatography with pulse amperometric detection (HPAEC-PAD, Dionex, Sunnyvale, CA, USA), using a PA1 column (Dionex, Sunnyvale, CA, USA) in an isocratic run of 18mM NaOH for 25 min, as described previously [11]. Total soluble sugars were determined as the sum of the glucose, fructose and sucrose values. Data on the amount of starch and soluble sugars in the tuberous roots were expressed on a fresh weight basis. All measurements were performed in triplicate.
2.3 Starch isolation
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The starch isolation procedure was performed from a pool of the tuberous roots of five plants (biological replicates) of each variety, according to methodology described by Bello-Pérez et al. [12]. Frozen tuberous roots were mixed in cold water (1 kg/1.5 L) in a domestic blender. The homogenate was filtered through Nylon-100 (100 µm mesh width); this process was repeated twice. The suspension containing the starch was refrigerated overnight and centrifuged for 5 min at 1000 g. The precipitated starch was washed three times in cold water and dried overnight in an oven.
2.4 Determination of the total phosphorus content of starch
The determination of the total phosphorus content of starch of cassava varieties was determined according to the method by Smith and Caruso [13]. Isolated starch (1 g) was mixed with ethanol and carbonized in a muffle furnace at 550-600ºC for 3 h. Samples were cooled at room temperature (RT), and 2 mL of diluted HNO3 (1:2) was added to the tube. The tube was then mixed well, covered, and incubated in a boiling-water bath for 30 min. The suspension was transferred to a 50 mL volumetric flask. Then, 1.5 mL of 0.25% ammonium vanadate and 1.5 mL of 5% ammonium molybdate were added and mixed well. Water was added to the mark and kept at RT for 30 min. A standard curve of phosphorus was prepared using KH2PO4 (at 1, 2, 3, 4 and 5 µg/mL) and realized concomitantly with the sample. The absorbance of the standard curve and samples was read at 355 nm against a reagent blank. All measurements were performed in triplicate.
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2.5 Amylose content
The amylose content was determined using an enzymatic method from Megazyme (Kit K-AMYL 04/06, Megazyme International Ireland Ltd., Wicklow, Ireland). All measurements were performed in duplicate.
2.6 Amylopectin branch chain-length distribution
The starch was debranched using isoamylase from Pseudomonas sp. (Megazyme International Ireland Ltd., Ireland), according to the procedure described by Wong and Jane [14]. The branch chain-length distribution of amylopectin was analyzed and calculated using a high-performance anion exchange chromatograph equipped with a pulsed amperometric detector (HPAEC-PAD, ICS 3000, Dionex, Sunnyvale, CA, USA). The debranched samples were filtered (0.22 µm membrane) and automatically injected into the HPAEC-PAD system (20 µL sample loop). The flow rate was 0.8 mL/min at 40oC. All eluents were prepared with ultrapure water (18 mΩ.cm) with N2 sparging. Eluent A was 150 mM NaOH, and eluent B was 500 mM sodium acetate and 150 mM NaOH. The side chains of amylopectin were separated using a Dionex CarboPacTM PA-100 guard column (4 x 50 mm) and a Dionex CarboPacTM PA-100 column (4 x 250 mm). The gradient of eluent B was 28 % at 0 min, 40 % at 15 min, and 72 % at 105 min. A maltodextrin mixture (DP 1-7) was used for identifying the homologous series of chain lengths. The data were analyzed using the Chromeleon software, version 6.8 (Dionex Corporation, USA). The analysis was performed in duplicate.
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2.7 Analysis of starch size distribution Starch size distribution and average diameter were determined using a Malvern-Mastersizer 2000 version 5.54 instrument (Malvern Instruments Ltd., Malvern, UK). The starch concentration was approximately 0.2 mg/mL (in isopropyl alcohol). In order to guarantee homogeneity, the samples were treated with soft ultrasound radiation during the experiment. All measurements were performed in duplicate.
2.8 Scanning electron microscopy (SEM)
The samples were fixed in stubs in a double face tape and coated with a 10
nm-thick
platinum
layer
in
a
Bal-tec
MED-020
Coating
System
(Kettleshulme, UK). The samples were analyzed in a FEI Quanta 600 FEG Scanning Electron Microscope (SEM; FEI Company, Oregon, USA). SEM observations were performed in the secondary electron mode operating at 5 kV.
2.9 Pasting properties
Pasting properties of starches were obtained using a Rapid Visco Analyser (RVA-4, Newport Scientific, Australia). A starch suspension (9%, dsb, w/w; 28 g total weight) was equilibrated at 30°C for 1 min, heated to 95°C at a rate of 6°C/min, held at 95°C for 5.5min, cooled down to 50°C at a rate of 6°C/min, and finally held at 50°C for 2 min. The suspensions were stirred at 160 rpm throughout the experiment. All determinations were performed in duplicate.
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2.10 Thermal properties Gelatinization and retrogradation properties of starches were determined using a differential scanning calorimeter (DSC-Pyris 1, Perkin Elmer, Norwalk, CT), as described by Peroni et al. [15]. Starch samples (2 mg, dry basis) were weighed in aluminum pans, mixed with distilled water (6 µL) and sealed. The samples were kept at RT for 2-3 h to equilibrate and were then scanned at a rate of 10°C/min over a temperature range of 25-100°C. An empty pan was used as a reference. Gelatinized samples were stored at 4°C for 7 days. The samples were analyzed for starch retrogradation using the same instrument and parameters. All measurements were performed in triplicate.
2.11 Multivariate statistical analysis
The data concerning all the features of the 10 cassava varieties were subjected to multivariate analysis via Principal Component Analysis (PCA) biplot with the assistance of XLSTAT-MX (XLSTAT, NY, USA) software. For this analysis, the correlation matrix was used and data standardization was performed by mean.
3 Results
Differences in starch and soluble sugars in the tuberous roots of the 10 cassava varieties were observed (Table 2). Among all varieties, the tuberous root of IAC 06-01, a variety commonly used in household consumption, was one
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of the richest in soluble sugars; however, this variety showed the lowest starch content. In contrast, IAC 90 was one of the richest in starch and consequently was one of the lowest in soluble sugars content. This is in agreement with the use of this variety for industrial starch production. SEM images of starches are shown in Figure 1. The images observed at high-magnification indicated that granules of starch of different cassava varieties presented rounded and slightly flattened surfaces, with exception of Caapora, which had a predominantly rounded shape. The average diameter varied from 11.812 m (Vassourinha Paulista) to 17.092 m (Caapora) (Table 2 and Figure 1). Vassourinha had the highest phosphorus content and the lowest average diameter of starch granules (11.812 m). In contrast, IAC 13 presented the lowest phosphorus content. In addition, IAC 576-70 and IAC 06-01 had the highest amylose content (24.34 % and 22.78 %, respectively) while Olho Junto and Cigana Preta revealed the lowest contents (14.80 % and 15.88 %, respectively; Table 2). Pasting properties are presented in Figure 2. Peak viscosity varied from 172 to 286 RVU for Olho Junto and IAC 576-70 starches, respectively. Pasting temperature varied from 62 °C for IAC 12 to 68 °C for IAC 90 starches. Olho Junto showed the lowest setback (26.8 RVU), while Cigana Preta and IAC 12 the highest (81.7 and 79.8 RVU, respectively). The gelatinization temperatures onset (To), peak temperature (Tp), conclusion (Tc), ∆Tgel, and enthalpy (∆H) are presented in Tables 3 . Thermal properties of cassava starches indicated that IAC 90 had the highest gelatinization temperatures (To, Tp and Tc; ). In contrast, Olho Junto and IAC 12
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indicated the lowest To and Tp of gelatinization. The first one had the more significant ∆T. Furthermore, Vassourinha showed the lowest Tc, ∆T and ∆H. Retrogradation temperatures (To, Tp and Tc), ∆H and percentage of retrogradation (%R) are presented in Table 4. IAC 576-70 and Caapora showed the highest temperatures, while Cigana Preta and IAC 90 presented the lowest values. IAC 90 showed the more significant values of ∆H and %R, while IAC 06-01 had the lowest %R. In the same way, the branch-chain length distribution of amylopectin of cassava starches were similar among the cassava varieties studied, and there was no significant difference among values regarding the degree of polymerization (DP) ≥37 and the average degree of polymerization (Table 5). The features of the 10 cassava varieties studied in this work were evaluated by PCA biplot analysis (Figure 3). The separation of the varieties seemed to be well correlated to some physicochemical properties of the investigated starches. Principal Component 1 (PC1) allowed the separation of the varieties Vassourinha Paulista and Olho Junto in the first square, which correlated with retrogradation temperatures (To, Tp, Tc), phosphorous content, soluble sugar content and branch-chain length distribution of amylopectin (DP 6-12, DP 13-24, DP 25-36). Furthermore, in the third square, PCA allowed the segregation of the samples IAC 06-01, IAC 576-70, Caapora and IAC 12, which were associated with some parameters of the gelatinization of starches (∆T and ∆H), and with the average diameter and size distribution (90 and 10%) of starch granules. Principal Component 2 (PC2) allowed the separation of IAC 14 and Cigana Preta in the second square, to which long B3-chains (DP 37) of amylopectin and the temperatures of gelatinization (To and Tp) are highly
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related. In contrast, the segregation of IAC 13 and IAC 90 was observed in the fourth square; the percentage of retrogradation (%R), Tc of gelatinization and ∆H of retrogradation were associated with these varieties.
4 Discussion
The structural and physicochemical characteristics of starch granules are related to their botanical sources. Granules with different sizes vary from submicron size to more than 100 microns [16]. Morphology and shapes vary from spherical, oval, polygonal, or dome-shaped to elongated [17]. Starch structural characteristics such as amylose content, the branch chain length distribution of amylopectin, phosphate monoester, phospholipids and lipid contents, shape and size of the granules affect their functional properties [18, 19]. Amylopectin content contributes to granule swelling and amylose and lipid contents seem to inhibit it. Moreover, phosphorous is an important noncarbohydrate component of starch that contributes to increase paste viscosity and lightness, and to decrease retrogradation [16, 20]. Thus, several properties of the starches isolated from 10 cassava varieties were evaluated. PC1 segregated Vassourinha and Olho Junto in the first square (Figure 3), and despite the starch granules from Vassourinha variety presenting the smallest size, this variety showed a high correlation in PCA with phosphorus content (Table 2) and a high proportion of intermediate and long branch-chain of amylopectin (Table 5). These starch granule characteristics are important to the frozen food industry and to the production of pudding and gumdrops, for instance, due to the starch of this variety contributing to the production of a
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clear and rigid starch pastes, as verified by the peak viscosity for this cultivar (238 RVU) in Figure 2. In addition, it can also be used in household consumption and for flour production (Table 1). As reported by Peroni et al. [15], low values of phosphorous content were found in cassava starch. In the case of Olho Junto, the proportions of short branch-chain of amylopectin (DP 612) and temperatures of retrogradation (To and Tp) were closely related. Thus, high proportion of short branch-chain of amylopectin (Table 5) contributes to decrease the temperature of gelatinization and pasting temperature (Table 3, Figure 2), a very important property in starch characterization, which is a feature of the starch type and suggests heterogeneity in the granule population. Due to the decrease in gelatinization temperature indicating a decline in the necessary energy to melt the crystals of amylopectin, the starch obtained from the Olho Junto variety may be used to produce instantaneous products, such as dried soup powder. The low setback shown for Olho Junto starch is related to the low amylose content (Table 2, Figure 2). PC2 allowed the separation of IAC 14 and Cigana Preta (Figure 3), two cassava varieties intended for industrial use: the former for the production of starch and the second for flour. These varieties were highly correlated with the long branch-chain of amylopectin (DP ≥ 37), temperature of gelatinization (To and Tp), average degree of polymerization and starch content. According to Hanashiro, Abe and Hizukuri [21], branch-chain length distribution can be divided into fractions when analyzed by high-performance anion-exchange chromatography with pulsed amperometric detection: fa, DP 6-12; fb1, DP 1324; fb2, DP 25-36; fb3, DP ≥ 37. These fractions, fa, fb1, fb2 and fb3, correspond to A-chains (external short chains), B1, B2 and long B3-chains,
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respectively. The high degree of polymerization and long branch-chain of amylopectin increase the gelatinization temperature, resulting in an increased temperature necessary for the melting the crystals of the starch granules, as reported by Jane et al. [18]. Moreover, the starches obtained from Cigana Preta and IAC 14 can be useful in processed and cold stored foods due to their low amylose content (Table 2). During cold storage, the reorganization of the starch molecules could result in syneresis, affecting the functional properties and thermal stability [6]. In this regard, Nwokocha et al. [5] reported high freezethaw stability of cassava starch paste when compared to that of cocoyam. They related that the lower freeze-thaw stability of cocoyam starch is due to a higher amylose content and retrogradation tendency and to a smaller granule size. In agreement with the previous observation by Peroni et al. [15], which found similar values for granule size, the cassava varieties IAC 06-01, IAC 57670, IAC 12 and Caapora showed that 90% of granules had diameters above 21 µm (Table 2). This fact explains the high ∆T and ∆H of gelatinization, whereas the average diameter of starch granules is associated with the energy necessary for melting the helices of starch, because large granules need more energy for melting. In contrast to the report by Nwokocha et al. [5], who observed granules of cassava starches with intermediate sizes, ranging from 2.81 to 14.03 µm, with a round shape and smooth surfaces, the wider gelatinization range (∆T) observed in these varieties suggests a greater heterogeneity of crystallites within the starch granules. In addition, among all the cassava varieties, IAC 576-70 showed the highest amylose content and significant starch content (Table 2). These features could generate a strong paste and a probable low viscosity peak.
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However, this variety showed the highest peak viscosity among the cassava starches studied (Figure 2). In comparison with others varieties, the physicochemical properties of IAC 576-70 are inappropriate for industrial use. IAC 12 and Caapora showed similar pasting properties as observed in Figure 2. Furthermore, as described before, they were correlated with the ∆T and ∆H of gelatinization and the average diameter of starch granules. Thus, these features may lead to a higher hot viscosity, improving the quality of some homemade products, such as tapiocas. Because the amylose content is related to gelatinization and retrogradation properties, affecting food processing and quality, it is quite important to assess the amylose content of the starch. The cassava variety IAC 90 separated in the fourth square by PC2 was correlated with the percentage of retrogradation (%R), Tc of gelatinization and ∆H of retrogradation. The highest Tc regarding this variety (Table 3) indicates heterogeneous crystals, and this fact justifies the high energy necessary to merge the helices. Furthermore, the highest %R observed to IAC 90 starch in comparison to other varieties studied (Table 4) become it less appropriated for frozen products due to its tendency of syneresis. This is a limiting property of the starch obtained from that variety, which is intended for industrial purposes (starch and flour production). IAC 13 also showed significant %R (Table 4) and low starch content (Table 2), and this justifies its use just for flour production. The application of a given type of starch is determined by its physicochemical properties. Starches isolated from different botanical sources differ in the amylose/amylopectin ratio and structure, length and degree of branching and the arrangement of these constituents within the starch granules [22-24]. According to Flores et al. [25], cassava starch became very useful in
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food industry because it has some inherent properties that are in high demand, such as high transparency of paste, and suitability for developing sauces for ready-to-eat foods, desserts, puddings, soups, fillings and gums due to its high viscosity.
5 Conclusions
The new information on the physicochemical properties of starches isolated from 10 cassava varieties may be useful for their application in the food industry. Due to large amount of data, PCA biplot analysis really contributed to a better visualization and understanding of the relations among the cassava varieties and their starches properties. In relation to novel uses, the starch from Vassourinha, a variety intended for household consumption and flour production, may also be of interest of the frozen food industry or to the production of pudding and gumdrops. Moreover, the low amylose content of starches from IAC 14 and Cigana Preta, a variety only exploited for flour production, can be used in processed and cold stored foods. Interestingly, Olho Junto starch may be used in the production of instantaneous products, while the high hot viscosity of IAC 12 and Caapora starches, which are varieties already used in starch production, are also appropriate to make homemade products. Finally, the data showed in this study corroborate that the application of some cassava varieties, such as the physicochemical properties of the starch of IAC 576-70, a variety used only for household consumption, are inappropriate for industrial use, in comparison with other varieties.
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6 References
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[13] Smith, R. J., Caruso, J. L. Determination of phosphorus. Chem Anal 1964, 4, 42-46.
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Figure legends
Figure 1. SEM images of cassava starches at two different magnifications.
Figure 2. Viscosity profiles of cassava starches measured by a rapid visco analyser. (-●-) IAC 576-70; (-▲-) IAC 14; (-▼-) IAC 90; (-■-) Olho Junto; (-♦-) Vassourinha Paulista; (-○-) Caapora; (-∆-) Cigana Preta; (- -) IAC 12;(-□-), IAC 13; (-◊-) IAC 06-01; (-─-) temperature.
Figure 3. Principal component analysis BIPLOT of the means of the values of features of cassava varieties using XLSTAT software. The first (PC1) and second (PC2) principal components are expressed as percentages of the variability. The samples of Cigana Preta (CIG), IAC 13 (13), IAC 12 (12), IAC 14 (14), Caapora (CAAP), IAC 90 (90), Olho Junto (OJ), IAC 06-01 (06-01), IAC 576-70 (576-70) and Vassourinha Paulista (VASS) are represented by the squares, whereas the features of cassava varieties are indicated by dots. Soluble sugars (SS), amylose content (AC), average diameter (AD), size distribution (10%) (SD10), size distribution (90%) (SD90), gelatinization (T0) (GT0), gelatinization (TP) (GTP), gelatinization (TC) (GTC), gelatinization (∆T) (G∆T), gelatinization (∆H) (G∆H), retrogradation (T0) (RT0), retrogradation (TP) (RTP), retrogradation (TC) (RTC), retrogradation (∆H) (R∆H), %R (%R), DP 612 (DP (6-12)), DP 13-24 (DP(13-24)), DP 25-36 (DP(25-36)), DP≥37 (DP37), average DP (ADP), highest detectable DP (HDDP).
Conflicts of interest The authors declare no competing financial interests.
23
24
Tables. Table 1. Attributes of the ten cassava varieties.
Variety
Use or application
Peel color
Pulp color
Carotenoids content (mg/kg)
Cyanogenic potential
Cigana Preta
F
Dark
White
~20
High
IAC 13
F
Clear
White
~20
Low
IAC 12
S
Dark
White
~20
Low
IAC 14
S
Dark
White
~20
N/A
Caapora
FS
Clear
White
~20
High
IAC 90
FS
Clear
White
~20
N/A
Olho Junto
FS
Dark
White
~20
High
IAC 06-01
H
Dark
Yellow
~1200
Low
IAC 576-70
H
Dark
Cream/Yellow
~400
Low
Vassourinha Paulista
FH
Dark
White
~20
Low
F: Flour production; S: Starch production; FS: Flour and Starch production; H: Household consumption; FH: Flour and Household consumption. N/A: Not available. Source: (www.iac.sp.gov.br/; www.embrapa.br/)
25
Table 2. Starch content, soluble sugars (tuberous roots of cassava varieties), phosphorus content, amylose content, average diameter and size distribution (tuberous roots starches). Starch content
Phosphorus content (%)
Amylose content Average diameter (%) (m)
Size distribution (%)
(g/100g)
Soluble sugars (g/100g)
Cigana Preta
32.33 ± 2.68 ab
4.21 ± 0.51 b
0.00919 ± 0.0001
15.88
12.575
18.506
7.587
IAC 13
28.28 ± 1.62 be
2.72 ± 0.06 cd
0.00342 ± 0.0001
19.90
13.459
19.746
8.138
IAC 12
32.41 ± 1.38 ab
1.84 ± 0.82 de
0.00561 ± 0.001
19.21
14.712
21.644
8.877
IAC 14
35.24 ± 1.53 a
3.61 ± 0.11 bc
0.00539 ± 0.0001
16.50
14.102
20.751
8.492
Caapora
29.93 ± 1.27 bd
2.66 ± 0.37 cd
0.00698 ± 0.001
16.57
17.092
25.060
10.374
IAC 90
35.37 ± 1.16 a
0.97 ± 0.21 e
0.00538 ± 0.001
19.77
13.506
19.523
8.385
Olho Junto
25.39 ± 1.06 e
2.78 ± 0.44 cd
0.00783 ± 0.001
14.80
14.941
21.960
9.028
IAC 06-01
17.28 ± 0.47 f
5.78 ± 0.53 a
0.00626 ± 0.001
22.78
15.823
23.264
9.537
IAC 576-70
31.72 ± 1.13 abc
4.08 ± 0.08 b
0.00861 ± 0.002
24.34
14.545
21.380
8.767
Vassourinha Paulista 27.80 ± 0.97 cde
6.39 ± 0.38 a
0.00932 ± 0.0001
17.01
11.812
17.606
6.935
Variety
90% (m)
Values with the same letter in the same column are not significantly different at p>0.05.
10% (m)
26
Table 3. Thermal properties of cassava starches.
Variety
Gelatinization temperatures (°C) To
Tp
∆T
Tc
∆Hgel (J/g)
Cigana Preta
57.2 ± 0.0 ab
61.7 ± 0.2 bc
66.9 ± 0.3 bc
9.7
14.2 ± 0.2 bc
IAC 13
57.2 ± 0.1 ab
61.2 ± 0.1 c
66.5 ± 0.1 bc
9.3
13.6 ± 0.3 cde
IAC 12
52.0 ± 0.5 e
57.9 ± 0.2 f
64.0 ± 0.1 e
12.0
13.4 ± 0.1 de
IAC 14
56.4 ± 0.3 b
61.4 ± 0.0 bc
66.4 ± 0.0 c
10.0
13.5 ± 0.2 cde
Caapora
54.3 ± 0.1 cd
61.0 ± 0.1 c
67.4 ± 0.2 b
13.1
14.0 ± 0.1 cd
IAC 90
58.2 ± 0.2 a
63.3 ± 0.1 a
69.2 ± 0.2 a
11.0
13.6 ± 0.2 cde
Olho Junto
49.2 ± 0.5 f
58.8 ± 0.1 ef
65.1 ± 0.1 d
15.9
14.9 ± 0.1 ab
IAC 06-01
52.0 ± 0.1 e
61.3 ± 0.1 c
67.0 ± 0.3 bc
14.9
15.1 ± 0.2 a
IAC 576-70
53.5 ± 0.7 d
62.3 ± 0.7 b
67.3 ± 0.7 bc
13.9
13.0 ± 0.2 e
Vassourinha Paulista
55.0 ± 0.0 c
59.2 ± 0.1 de
63.5 ± 0.0 e
8.5
11.9 ± 0.0 f
Values with the same letter lower case in the same column are not significantly different at p>0.05; *
To = onset temperature, Tp = peak temperature, Tc = conclusion temperature, ∆T = Tc - To, ∆Hgel = enthalpy change.
27
Table 4. Thermal properties of retrograded cassava starches. Retrogradation temperatures (°C) Variety
To
Tp
Tc
∆Hret (J/g)
%R
3.2 ± 0.2 bc
23
3.6 ± 0.4 ab
26
Cigana Preta
41.2 ± 0.5 g
52.8 ± 0.0 c
59.6 ± 0.0 bc
IAC 13
45.0 ± 1.4 ef
53.5 ± 0.5 bc
60.3 ± 0.2
IAC 12
47.4 ± 0.1 cd
53.1 ± 0.0 bc
59.4 ± 0.3 c
2.6 ± 0.3 bcd
20
IAC 14
47.6 ± 0.9 bcd
53.8 ± 0.0 b
59.8 ± 0.2 abc
2.1 ± 0.2 d
16
Caapora
49.9 ± 0.3 ab
56.0 ± 0.2 a
60.5 ± 0.1 a
3.0 ± 0.2 bcd
21
IAC 90
41.8 ± 0.3 g
52.8 ± 0.0 c
59.8 ± 0.2 abc
4.4 ± 0.3 a
32
Olho Junto
46.1 ± 0.2 de
53.8 ± 0.0 b
59.4 ± 0.3 c
2.7 ± 0.1 bcd
19
IAC 06-01
48.5 ± 0.7 abcd
52.8 ± 0.0 c
59.9 ± 0.1 abc
2.2 ± 0.0 cd
15
IAC 576-70
50.1 ± 0.5 a
55.6 ± 0.5 a
60.6 ± 0.3 a
2.5 ± 0.2 cd
19
49.5 ± 0.1 abc
53.2 ± 0.1 bc
59.8 ± 0.2 abc
2.3 ± 0.4 cd
19
Vassourinha Paulista
ab
Values with the same letter lower case in the same column are not significantly different at p>0.05; *
To = onset temperature, Tp = peak temperature, Tc = conclusion temperature, ∆Hret = enthalpy change; % R = [(∆Hret / ∆Hgel)x 100]
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Table 5. Branch-chain length distribution of amylopectin of cassava starches.
DP ≥ 37
Average DP
Highest detectable DP
Branch-chain length distribution (%) Variety DP 6-12
DP 13-24
DP 25-36
Cigana Preta
31.4 ± 0.1 abc
46.6 ± 0.3 abc
11.9 ± 0.1 d
10.1 ± 0.2 a
19.3 ± 0.1 a
81
IAC 13
31.5 ± 0.2 abc
46.1 ± 0.2 bcd
12.1 ± 0.1 bcd
10.2 ± 0.3 a
19.4 ± 0.1 a
86
IAC 12
32.1 ± 0.2 a
45.9 ± 0.1 cd
12.2 ± 0.1 bcd
9.8 ± 0.2 a
19.2 ± 0.1 a
79
IAC 14
31.3 ± 0.2 abc
46.4 ± 0.2 abcd
12.1 ± 0.1 cd
10.3 ± 0.3 a
19.4 ± 0.1 a
82
Caapora
30.9 ± 0.2 cd
46.9 ± 0.1 a
12.2 ± 0.0 bcd
10.0 ± 0.4 a
19.4 ± 0.1 a
79
IAC 90
30.3 ± 0.2 d
46.9 ± 0.1 ab
12.3 ± 0.1 abcd
10.5 ± 0.2 a
19.6 ± 0.1 a
78
Olho Junto
31.9 ± 0.3 ab
45.7 ± 0.1 d
12.6 ± 0.1 a
9.9 ± 0.2 a
19.3 ± 0.1 a
76
IAC 06-01
31.9 ± 0.3 ab
46.0 ± 0.0 bcd
12.0 ± 0.1 cd
10.1 ± 0.2 a
19.3 ± 0.1 a
79
IAC 576-70
31.0 ± 0.2 bcd
46.3 ± 0.1 abcd
12.4 ± 0.1 ab
10.2 ± 0.2 a
19.5 ± 0.1 a
81
Vassourinha Paulista
31.2 ± 0.2 abcd
46.0 ± 0.1 bcd
12.4 ± 0.0 ab
10.3 ± 0.2 a
19.5 ± 0.1 a
82
Values with the same letter in the same column are not significantly different at p>0.05. DP: degree of polymerization
Figure 1.
Figure 2.
Figure 3.
