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Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch
LWT - Food Science and Technology xxx (2015) 1e8
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Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch Phuong Lan Tran a, b, Dang Hai Dang Nguyen a, Viet Ha Do c, Young-Lim Kim c, Sunghoon Park d, Sang-Ho Yoo e, Suyong Lee e, Yong-Ro Kim c, * a
Department of Foodservice Management and Nutrition, Sangmyung University, Seoul, 110-743, Republic of Korea Department of Food Technology, An Giang University, An Giang, 076, Viet Nam Center for Food and Bioconvergence, Department of Biosystems and Biomaterials Science and Engineering, Seoul National University, Seoul, 151-742, Republic of Korea d Institute of Life Sciences and Resources and Graduate School of Biotechnology, Kyung Hee University, Yongin, 446-701, Republic of Korea e Department of Food Science and Technology, Sejong University, Seoul, 143-747, Republic of Korea b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 September 2014 Received in revised form 30 January 2015 Accepted 30 January 2015 Available online xxx
Jackfruit seed starch (JFSS) cultivated in Vietnam had a high amylose content (~44%). Differential scanning calorimetry thermogram of JFSS consisted of two separate endothermic peaks with distinct onset and conclusion temperatures. When JFSS was heated at 70 C, the first endothermic peak disappeared, whereas the second endotherm remained. The partially-gelatinized JFSS still possessed Atype X-ray diffraction pattern. SEM images showed that the rim of the starch granule at the hollow bottom of the bell shape first melted during the partial gelatinization at 70 C. Both native and partiallygelatinized JFSS produced soft and highly elastic gels, but their moduli differed slightly. Additionally, the partially-gelatinized JFSS was successfully used to produce genistinecycloamylose (CA) and amylose elysolecithin complexes with and without 4-a-glucanotransferase. Water sorption isotherms of partially gelatinized JFSS showed higher water-holding capacity than that of the native starch. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Jackfruit (Artocarpus heterophyllus Lam.) seed starch Partial gelatinization Differential scanning calorimetry Dynamic rheological properties Microstructures
1. Introduction Jackfruit (Artocarpus heterophyllus Lam.), which is widely cultivated in tropical countries including Vietnam, has edible bulbs of yellow flesh and seeds. Jackfruit seeds (8e15% of the total fruit weight) have fairly high carbohydrate and protein contents (Bobbio, El-Dash, Bobbio, & Rodrigues, 1978; Kabir, 1998; Kumar, Singh, Abidi, Upadhyay, & Singh, 1988; Singh, Kumar, & Singh, 1991). Jackfruit seeds also contain many minerals, lignans, isoflavones, saponins, and phytonutrients (James & Friday, 2010). Thus, jackfruit seeds are used as ingredients in many culinary preparations. The granules of jackfruit seed starch (JFSS) have bell shape and a smooth surface; the granule size ranges from 5 to 10 mm (Kittipongpatana & Kittipongpatana, 2011). JFSS has great potential in the food industry, especially for use as a thickener, stabilizer, and binding agent (Rengsutthi & Charoenrein, 2011).
* Corresponding author. Tel.: þ82 2 880 4607. E-mail address: [email protected] (Y.-R. Kim).
Recently, there have been several studies on the physicochemical properties of JFSS (Kittipongpatana & Kittipongpatana, 2011; Mukprasirt & Sajjaanantakul, 2004; Rengsutthi & Charoenrein, 2011; Tulyathan, Tananuwong, Songjinda, & Jaiboon, 2002). However, the properties of its different varieties appear to vary. Modified starches have been prepared by various techniques, such as enzymatic, chemical, and physical treatments and partial gelatinization, and have been used widely in the food and pharmaceutical industries (Abbas, Khalil, & Hussin, 2010). There are many processes for starch modification, one of which is hydrothermal treatment (Chung, Lim, & Lim, 2006). Traditionally, the preparation of partially-gelatinized starch was carried out with heat treatment of varying duration at the gelatinization temperature of the relevant starch. The characteristics of the resulting products varied, depending on the processing parameters such as the processing time and temperature. Difficulties in controlling the processing may lead to a degree of gelatinization that is higher than planned or desirable for the product. Partial gelatinization of starch provides a mixture of the properties of both native and fully gelatinized starches. Thus, partially-gelatinized
http://dx.doi.org/10.1016/j.lwt.2015.01.054 0023-6438/© 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Tran, P. L., et al., Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch, LWT - Food Science and Technology (2015), http://dx.doi.org/10.1016/j.lwt.2015.01.054
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P.L. Tran et al. / LWT - Food Science and Technology xxx (2015) 1e8
starch has been used as a binder and disintegrant. Moreover, after partial gelatinization treatment, starch transforms from an amorphous state to a more ordered or crystalline state that has different digestion properties, providing benefits for the dietary management of metabolic disorders (Chung et al., 2006). Preliminary tests of JFSS gelatinization indicated that it had unique gelatinization characteristics, with two endothermic peaks, each with a distinct onset temperature, which might make it possible to produce a product with unique qualities through temperature-controlled thermal processing. In this study, native and partially gelatinized Vietnamese JFSS were investigated to better understand their physicochemical properties and potential uses. 2. Materials and methods
connected in tandem and equilibrated at room temperature. The molecular weight of the samples was analyzed using the ASTRA software (ver. 4.90.07; Wyatt Technology), and the Berry extrapolation method was used for curve fitting with a dn/dc value of 0.146 mL/g. 2.4. Purification of thermostable 4-a-glucanotransferase (TAaGT) enzyme The 4-a-glucanotransferase gene, cloned by Park et al. (2007), encoded the TAaGT enzyme. The plasmid was expressed in E. coli MC1061, and the target enzyme was isolated using a nickelnitrilotriacetic acid (Ni-NTA) column (Qiagen, Hilden, Germany) (Park et al., 2007). The purity of TAaGT enzymes was confirmed by SDS-PAGE.
2.1. Isolation of starch Jackfruit seeds were purchased at a local market in An Giang, Vietnam. The seeds were washed, and the white aril was peeled off. Next, the thin brown spermoderm covers were removed following the method of Tulyathan et al. (2002). The JFSS was isolated by wetpowdering the raw material with 0.05 mol/L aqueous NaOH, screening the slurry through a 100-mm testing sieve, and subjecting it to centrifugation (8000 g, 15 min). The sediment was resuspended in distilled water and centrifuged again. The raw starch was washed four times with two volumes of ethanol to completely remove organic-soluble components, especially lipids, and was then washed several times more with distilled water until the starch was free of color. The starch was dried in an air oven at 40 ± 1 C until the final moisture content was <13%. 2.2. Isolation of amylose and amylopectin Amylose and amylopectin were isolated following the method of Song and Jane (2000) with slight modifications. The starch slurry (13.3 g/L) was heated and stirred in a water bath at 96 C for 1 h. The starch solution was filtered to remove insoluble residues, adjusted to pH 6.3 with phosphate buffer, autoclaved at 121 C for 1 h, and then boiled and stirred at 96 C for 2 h to disperse the starch molecules. One fifth volume of n-butyl alcohol was then added to the starch solution. The solution was cooled to room temperature over a period of 24e36 h. The amyloseebutyl alcohol complex crystals that formed and precipitated during cooling were separated by centrifugation (8700 g, 30 min). The solution was treated twice more with n-butyl alcohol to obtain residual amylose. The amylopectin remaining in the supernatant was obtained by precipitation with at least two volumes of ethanol, followed by centrifugation. The amylose content of the native starch of jackfruit seed was measured colorimetrically using Juliano's method (Juliano, 1971) based on amyloseeiodine complex formation, as described by Tran, Lee, and Park (2013). 2.3. Size exclusion chromatography-multi-angle laser scatteringrefractive index detection (SEC-MALLS-RI)
2.5. Preparation of partially gelatinized starch The JFSS was dispersed in distilled water (weight ratio of 3:7) at room temperature. Each batch of dispersion was heated and shaken at 70 C for 20, 30, or 60 min. The partially-gelatinized starch was cooled, and a double volume of ethanol was added with continuous stirring. Ethanol was then removed by centrifugation. The partially gelatinized JFSS was dried in an oven at 40 ± 1 C for 24 h and used for further analysis.
2.6. High-performance anion exchange chromatography (HPAEC) The amylopectin branch chains of the native and modified samples were debranched with isoamylase (Hyashibara Biochemical Labs, Okayama, Japan) in 50 mmol/L sodium acetate buffer (pH 4.3) at 60 C for 72 h. The amylopectin branch chain length distribution was analyzed using an HPAEC system (Dionex-300, Dionex, Sunnyvale, CA, USA) with a pulsed amperometric detector (ED40, Dionex). The system was equipped with a CarboPac PA-1 anion exchange column (4 250 mm, Dionex). The sample was eluted with a 10e70% (v/v) gradient of 600 mmol/L sodium acetate in 150 mmol/L sodium hydroxide at a flow rate of 1.0 mL/min (Park et al., 2007).
2.7. High-performance liquid chromatography (HPLC) The genistineCA complex formation of the JFSS treated with TAaGT in the presence of genistin was determined using a Waters 600S HPLC system with a 150 3.9-mm i.d. Nova-Pak C18 column and an SLC 200 UVevis detector (Samsung, Seoul, Korea) set at 254 nm. For the gradient solvent system, solvent A (water/formic acid, 100:0.1, v/v) and solvent B (100% acetonitrile) were used, with solvent B increasing gradually from 10 to 50% during a 20-min interval at a flow rate of 1 mL/min.
2.8. Differential scanning calorimetry (DSC) Amylose and amylopectin of the JFSS were dissolved in 1 mol/L NaOH at 75 C and then neutralized with 1 mol/L HCl and diluted with 50 mmol/L NaNO3 to a final concentration of 5 g/L. The molecular weights of amylose and amylopectin were determined by SEC-MALLS (Dawn DSP, Wyatt Technology, Santa Barbara, CA, USA, and Waters 410, Bedford, MA, USA) at a constant flow rate of 0.4 mL/min in 100 mmol/L NaNO3 containing 0.2 g/L NaN3. Two columns, a Shodex OHpak SB-806 HQ (8.0 300 mm; Showa Denko) and a YMC-Pack-Diol 120G (8.0 300 mm; YMC), were
The thermal properties of the native and modified JFSS were determined using DSC (Seiko Instruments [SII] SSC/5200, Tokyo, Japan) after calibration with indium (156.6 C, 28.59 J/g) and tin (232.2 C, 60.62 J/g). A 2.5 mg sample and 7.5 mL distilled water were sealed hermetically in an aluminum pan. DSC thermogram was obtained while the pan was heated from 30 to 160 C at 10 C/ min. The test was carried out with a pan filled with distilled water as a reference, and analyses were performed in triplicate.
Please cite this article in press as: Tran, P. L., et al., Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch, LWT - Food Science and Technology (2015), http://dx.doi.org/10.1016/j.lwt.2015.01.054
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2.9. Rheological and pasting properties The paste/gel characteristics of the starch were determined using a dynamic rheological test, as described by Tran et al. (2013). The starch paste samples (5% starch content) heated in a boiling water bath for 30 min with stirring were loaded into a rheometer between parallel 40-mm diameter plates at a gap distance of 1 mm. After trimming off the overloaded portion of sample around the plates, a thin layer of silicon oil was applied to the open side of the sample to prevent moisture loss. A solvent trap was also used to minimize water loss during the measurements. All the measurements were conducted at 1% strain, which was within the linear viscoelastic region (data not shown). A time sweep test was conducted at a fixed frequency of 1 Hz by recording the storage (G0 ) and loss (G00 ) moduli continuously at 4 C as a function of time over 2 h. At the end of the gelation period, frequency sweep tests were performed over the range of 0.1e10 Hz. The pasting properties of the native and partially gelatinized JFSS were investigated using a Rapid Visco Analyzer (RVA 3D, Newport Scientific, Warriewood NSW, Australia). Samples of starch (3 g, 11.2% moisture content) were dispersed in 25 g distilled water in an aluminum canister. The starch slurry was initially mixed and then held at 50 C for 2 min, heated to 95 C at 12 C/min, held at 95 C for 2 min 30 s, cooled to 50 C, and finally held at 50 C for 2 min at 160 rpm. The parameters analyzed were pasting temperature, peak viscosity, final viscosity, breakdown viscosity, and setback viscosity. 2.10. Scanning electron microscopy (SEM) The samples were coated with gold using a magnetron sputter coater (Jeol, MSC-101) before being observed with the SEM (Jeol, JSM-5600LV) with a large field detector. The acceleration voltage was 5e15 kV under low vacuum mode (0.7e0.8 torr). Pictures were captured using automatic image capture software (SEM Control User Interface, ver. 2.11). 2.11. X-ray diffractometry (XRD) The XRD patterns were recorded using a powder X-ray diffractometer (D8 Advance, Bruker, Karlsruhe, Germany) with Cu-Ka radiation (l ¼ 1.5406 Å) and crystal graphite monochromator applied at a voltage of 40 kV and a 45 mA current. All the samples were analyzed in the 2q angle range of 5 e40 , and process parameters were set as follow: scan step size, 0.02 (2q); scan step time, 1 s.
known water activities (LiCl-0.11, K2CO3-0.48, NaCl-0.75, BaCl2jean, Blanchard, Jeantet, & Schuck, 2011). 0.90) at 25 C (Zhu, Me The samples were allowed to equilibrate for approximately 10 days until there was no discernible weight change (±0.001 g). The equilibrium moisture contents were measured and plotted against water activities of different salt solutions in desiccators. Each experiment was conducted in triplicate. 3. Results and discussion 3.1. Content and molecular weight of the amylose and amylopectin in the JFSS The JFSS from Vietnam had a relatively high apparent amylose content of 43.96%, compared to previously reported amylose contents of various JFSS cultivars from different regions (Bobbio et al., 1978; Dutta, Paul, Kalita, & Mahanta, 2011; Kittipongpatana & Kittipongpatana, 2011; Mukprasirt & Sajjaanantakul, 2004; Tongdang, 2008; Tulyathan et al., 2002). The molecular weights of amylose and amylopectin of the JFSS were measured to be (5.13 ± 0.36) 106 g mol1 and (2.22 ± 0.02) 107 g mol1, respectively, which were similar to those of water caltrop starch (Tran et al., 2013) and within the average ranges for amylose and amylopectin of cereal starches, while those of other JFSS varieties were not reported yet. Chung, Han, Yoo, Seib, and Lim (2008) and Jane and Chen (1992) reported that the molecular weight of amylose and amylopectin and amylopectin branch chain length had effects on the pasting properties of starches. 3.2. Amylopectin branch chain length distribution of the JFSS The amylopectin branch chain length distribution pattern of the JFSS was somewhat broad, with the highest peak at DP 13 and a shoulder at DP 18 (Fig. 1). Considering that the average chain length rez & (CL) of most amylopectins lies in the range of 17e26 (Pe Bertoft, 2010), the JFSS amylopectin had a fairly short average CL of 18.05. As suggested by Hanashiro, Abe and Hizukuri (1996), the amylopectin branch chains of the JFSS, up to approximately DP 60, was classified in four fractions: A, B1, B2, and B3 chains (Fig. 1). The proportion of A chain (DP 6e12) was 24.98%. The amount of this group has been correlated with the crystallinity type and average CL for various amylopectin samples (Hizukuri, 1985). Due to the short average CL, the JFSS had high A chain content in A-crystalline material. The amount of B1 chain (DP 13e24) was highest (50.10%), and the proportions of the B2 chain (DP 25e36) and B3 chain
2.12. Enzymatic modification of the JFSS supplemented with genistin
2.13. Moisture sorption isotherm Native JFSS, partially-gelatinized JFSS, partially-gelatinized JFSS with genistin, and partially-gelatinized JFSS with genistin treated with TAaGT, respectively, were weighted (0.5 ± 0.001 g) in disposable aluminum dishes (57 mm diameter) and placed inside desiccators that contained different saturated salt solutions with
5
B1
A
B2
B3
4
Relative peak area (%)
The JFSS was dispersed in 50 mmol/L TriseHCl buffer (pH 7.5) at a ratio of 1:3 and supplemented with genistin at a final concentration of 0.1 mM. The mixture was then treated with TAaGT (0.05 U/mg of substrate) at 70 C for 1 h. For the detection of the CAegenistin complex, the reaction mixture was treated with bamylase from Bacillus cereus using 0.3 U/mL of reaction mixture for 1 h at 40 C.
3
3
2
1
0 10
20
30
40
50
60
Degree of polymerization (DP)
Fig. 1. Branch chain length distribution of the JFSS amylopectin. A, DP 6e12; B, DP 12e24; B2, DP 25e36; and B3, DP > 37.
Please cite this article in press as: Tran, P. L., et al., Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch, LWT - Food Science and Technology (2015), http://dx.doi.org/10.1016/j.lwt.2015.01.054
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P.L. Tran et al. / LWT - Food Science and Technology xxx (2015) 1e8
(DP > 37) were 14.56% and 10.36%, respectively. Additionally, the area percentages of DPs in the A chain fraction were high in comparison with the other fractions (Fig. 1) and other starches (Hizukuri, 1985). 3.3. Thermal properties of native and partially gelatinized JFSS Thermal properties of the native and partially gelatinized JFSS (at 70 C for 1 h) were analyzed by DSC. The JFSS demonstrated two distinguishable endothermic peaks with distinct onset, peak, and conclusion temperatures: To ¼ 58.4 C, Tp ¼ 66.4 C for peak I and To ¼ 79 C, Tp ¼ 82.7 C for peak II (Table 1 and Fig. 2A). In contrast, JFSS from Thailand displayed only one endothermic peak (Kittipongpatana & Kittipongpatana, 2011; Mukprasirt & Sajjaanantakul, 2004; Tongdang, 2008). Both endothermic peaks completely disappeared when the sample was rescanned after heating up to 120 C (Fig. 2B), indicating that both endotherms were gelatinization peaks. When the JFSS sample was heat-treated at 70 C for 1 h, cooled to room temperature, and rescanned, the peak I completely disappeared and the endothermic peak II remained (Fig. 2C and Table 1). The results implied that the heat treatment at 70 C gelatinized a part of the JFSS whereas the rest parts remained ungelatinized. This also implied that there might be two different groups of crystalline structure that were located in either different starch granules or different compartments of the same granule. The degree of gelatinization of the partiallygelatinized JFSS, estimated from gelatinization enthalpies in Table 1, was approximately 53%.
The starch granules became more concave and wrinkled during heat processing (Fig. 3 BeD). At 70 C, starch granules did not show noticeable swelling, whereas amylose continuously leached out to cover starch granules and finally form lumps (Fig. 3D). 3.5. Pasting properties of native and partially gelatinized JFSS Pasting properties of the JFSS are summarized in Table 2 and compared with those of other starches previously reported. Even though pasting properties, especially peak viscosity, depend on experimental conditions such as solids content, direct comparison of published data in Table 2 requires extreme caution. This notwithstanding, some differences in the pasting properties of the JFSS were observed compared to other starches. The pasting temperature of the JFSS (64.2 C) was relatively low, just above that of potato starch (63.0 C), whereas peak viscosity was relatively high (3.8 Pa.s). Also, the final viscosity and setback of the JFSS were significantly high (5.2 Pa.s and 2.4 Pa.s, respectively), suggesting that the JFSS formed a highly viscous paste capable of forming a solid gel network. The pasting temperature and peak viscosity of partially gelatinized JFSS was slightly lower than that of the native starch. However, the partially gelatinized JFSS had higher final viscosity and setback values compared to those of the native sample (Table 2). Pasting profile depicted in Fig. 4 might provide
3.4. SEM image analysis of partially gelatinized JFSS The JFSS granules had mainly bell shapes and hollow bottoms, similar to other varieties of JFSS described in previous reports (Fig. 3A: arrow a) (Bobbio et al., 1978; Kittipongpatana & Kittipongpatana, 2011; Tongdang, 2008). The JFSS granular morphologies changed with heat treatment time at 70 C (20, 30, and 60 min) (Fig. 3 BeD). The outermost layers at the bottom of the bellshaped granules were hydrated, making the surface of the granules less smooth (Fig. 3B: arrow b), with the rim of the bell-shaped granules melting first probably due to the large specific surface (Fig. 3 BeC: arrow b) and faster penetration of water molecules. This might result in a low onset temperature of 59 C (peak I, Fig. 2A), whereas the upper part of the granule might gelatinize at a higher temperature, 79 C (peak II, Fig. 2A). However, this is a rough postulation based on qualitative microscopic observations. More intensive investigation will be required to clarify the above claims.
Table 1 Thermal properties of the native and modified JFSS. Native Peak 1 To ( C) Tp ( C) Tc ( C) DH (J g1) Peak 2 To ( C) Tp ( C) Tc ( C) DH (J g1) Peak 3 To ( C) Tp ( C) Tc ( C) DH (J g1)
58.4 66.4 74.3 5.64 79.0 82.7 88.5 5.68 e e e e
± ± ± ± ± ± ± ±
Partial Complex with GenistineCA gelatinizationa lysolecithin complex 0.26 0.10 0.30 0.05 0.20 0.10 0.27 0.02
e e e e 79.0 83.3 88.1 5.33 e e e e
± ± ± ±
0.15 0.20 0.00 0.01
e e e e 82.0 ± 0.17 84.8 ± 0.10 89.8 ± 0.10 6.59 ± 0.03 99.7 ± 0.10 106.7 ± 0.10 112.9 ± 0.00 5.23 ± 0.01
e e e e e e e e 88.7 92.7 97.8 8.05
± ± ± ±
0.20 0.25 0.10 0.01
To, onset temperature; Tp, peak temperature; Tc, conclusion temperature; e, not detected. a Partially gelatinized at 70 C for 1 h.
Fig. 2. Thermal property analysis of the JFSS samples. (A) Native JFSS, (B) native JFSS scanned a second time, (C) partially gelatinized JFSS, (D) mixture of partially gelatinized JFSS with lysolecithineamylose complex, (E) mixture of partially gelatinized JFSS with genistineCA complex.
Please cite this article in press as: Tran, P. L., et al., Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch, LWT - Food Science and Technology (2015), http://dx.doi.org/10.1016/j.lwt.2015.01.054
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5
Fig. 3. Scanning electron microscopy (SEM) images of (A) native JFSS and (B), (C), and (D) partially gelatinized JFSS at 70 C for 20, 30, or 60 min, respectively. Arrow a: concave and hollow region; arrow b: rough surface and partially gelatinized region; arrow c: ungelatinized granule partially covered with partially gelatinized starch.
some points to discuss in comparison with DSC thermograms (Fig. 2) and SEM micrograms (Fig. 3). The native JFSS showed a shoulder at the beginning of viscosity increase, which could indicate the existence of two different melting temperatures as seen in the DSC thermogram (Fig. 2A). As for the partially-gelatinized starch, the initial viscosity was slightly higher than that of control probably due to the partial amylose leaching and minor swelling of starch granules as evidenced in Fig. 3 and the viscosity increase was rather gradual making the shoulder less obvious. During the stage of the sharpest viscosity increase after the shoulder or gradual increase, both graphs overlapped, implying that swelling of starch granules was mainly governed by the second melting at above 80 C (Figs. 2 A and C). The fact that starch granules did not swell significantly after the heat treatment at 70 C (Fig. 3) could support this. As a result, partial gelatinization of the JFSS at 70 C converted
the gelatinization profile from bi-modal to uni-modal and modified the pasting profile that were characterized as lower breakdown thus improved stability and higher final viscosity. 3.6. Rheological properties of the JFSS Immediately after preparing native and partially-gelatinized JFSS paste samples (5% starch content) by heating in a boiling water bath for 1 h, respectively, dynamic rheological properties were measured at 4 C over time to investigate their gelation characteristics (Fig. 5 top). Both native and partially-gelatinized JFSS paste samples showed a relatively rapid increase in G0 and an almost constant G00 , thus a rapid decrease in d down to ~5 during the initial 50 min of gelation period at 4 C. Frequency sweep test conducted at the end of 2 h gelation period (Fig. 5 bottom) revealed
Table 2 Pasting properties of JFSS in comparison with other starches. Starch
Pasting temp. ( C)
Jackfruit seeda Partially gelatinized JFSSa,b Wheat Sweet potato Cassava Buckwheat Water caltrop Cowpea Acorn Corn Potato
64.2 58.7 66.5 66.9 68.4 _ 75.0 76.0 77.0 81.0 63.0
a b
± ± ± ± ±
0.07 0.06 0.07 0.30 0.10
± ± ± ± ±
0.00 0.00 0.00 0.00 0.00
Peak viscosity (Pa.s) 3.8 3.3 0.4 0.9 1.2 4.6 3.0 1.7 1.3 1.2 7.6
± ± ± ± ± ± ± ± ± ± ±
0.01 0.08 0.01 0.01 0.01 0.04 0.00 0.00 0.00 0.00 0.00
Breakdown (Pa.s) 1.3 0.9 0.2 0.5 0.7 2.4 1.0 0.6 0.5 0.4 6.0
± ± ± ± ± ± ± ± ± ± ±
0.02 0.01 0.02 0.00 0.00 0.04 0.00 0.00 0.00 0.00 0.00
Final viscosity (Pa.s) 5.2 5.5 0.5 0.6 0.7 0.4 6.5 2.2 1.5 1.2 2.5
± ± ± ± ± ± ± ± ± ± ±
0.06 0.05 0.02 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00
Setback (Pa.s) 2.4 2.8 0.3 0.5 0.8 1.8 4.5 1.1 0.8 0.5 0.8
± ± ± ± ± ± ± ± ± ± ±
0.05 0.08 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00
Reference This study This study (Li, Zhang, Wei, Zhang & Zhang, 2014) (Li, Zhang, Wei, Zhang & Zhang, 2014) (Li, Zhang, Wei, Zhang & Zhang, 2014) (Li et al., 2014) (Tran et al., 2013) (Won, Choi, Lim, Cho, & Lim, 2000) (Won et al., 2000) (Won et al., 2000) (Won et al., 2000)
Data are averages of triplicate values. Partially gelatinized at 70 C for 1 h.
Please cite this article in press as: Tran, P. L., et al., Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch, LWT - Food Science and Technology (2015), http://dx.doi.org/10.1016/j.lwt.2015.01.054
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Fig. 4. Pasting profile of (A) native and (B) partially gelatinized JFSS (10% starch content). A dotted line represents temperature program.
that G0 was almost independent of frequency maintaining fairly large different between G0 and G00 . The frequency independency and low phase angle indicated the JFSS gel was highly “solid-like (elastic)”. Generally, the amylose content of starch affects the
dynamic viscoelasticity of starch gel: starch with high amylose content normally shows high G0 (Lu et al., 2009). Even though the JFSS paste formed a solid gel after 50 min at 4 C, the G0 of the JFSS gel was surprisingly low (120e170 Pa) considering its high amylose content (~44%). This was obvious when compared to another high amylose tropical starch, water caltrop starch (amylose content was 47% and G0 of 5% gel formed at 20 C was ~1200 Pa) (Tran et al., 2013), and even to maize starch (amylose content was 27e28% and G0 of 6% gel formed at 25 C was ~800 Pa) (Loisel, MaacheRezzoug, Esneault, & Doublier, 2006). Although amylose content is an important factor for starch gelation, properties of starch dispersion/gel are not simply governed by its composition and molecular structures (Hermansson & Svegmark, 1996). Starch gel properties are determined by various physicochemical interactions such as the formation of continuous phase by leached amylose, aggregation of leached amylose, integrity and space-filling of dispersed swollen granules (Hermansson & Svegmark, 1996). These complex interactions might be modified in the partially-gelatinized JFSS, causing slightly different gel properties compared to those of the native JFSS as shown in Fig. 5. The rheological data obtained in this study were not enough to fully explain the complexity of the JFSS gel. Instead, rather practical information on the JFSS gel, the formation of soft but highly elastic gel, could benefit various industries searching for new starch materials.
3.7. Powder XRD patterns of native and partially gelatinized JFSS Powder XRD patterns of native, partially-gelatinized (at 70 C for 1 h), and fully-gelatinized JFSS were obtained to investigate their crystalline structures (Fig. 6). The native JFSS showed a typical A-type crystallinity pattern with prominent diffraction peaks at Bragg angles (2q) of 15 , 17, 18 , 23 , which was in agreement with previous reports (Kittipongpatana & Kittipongpatana, 2011; Tulyathan et al., 2002). Partial gelatinization of the JFSS at 70 C fairly diminished the crystallinity peaks. However, partial crystallinity with A-type pattern still remained after heat treatment at 70 C, which was more obvious when compared to the XRD pattern of the fully-gelatinized JFSS. Remaining partial crystallinity after heat treatment at 70 C could be related to the relatively wellconserved granular integrity of the partially-gelatinized JFSS without significant swelling as shown in Fig. 3.
Fig. 5. Dynamic rheological properties of the JFSS gel (5% starch content) obtained from time sweep (top) and frequency sweep (bottom) tests at 4 C: (A) G0 of native JFSS, (B) G0 of partially gelatinized JFSS, (C) G00 of native JFSS, (D) G00 of partially gelatinized JFSS, (E) phase angle (d) of native JFSS, (F) d of partially gelatinized JFSS.
Fig. 6. Powder X-ray diffraction patterns of (A) native, (B) partially-gelatinized, and (C) fully-gelatinized JFSS.
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Fig. 7. HPLC analysis of genistineCA complex formation in the partially gelatinized JFSS treated with TAaGT. (A) Before and (B) after b-amylase treatment in which 1, genistin; 2, glycosylegenistin; 3, maltosylegenistin; 4, maltotriosylegenistin; 5, maltotetraosylegenistin; 6, maltopentosylegenistin were added; 7, CA-genistin complex.
3.8. Formation of inclusion complexes with partially gelatinized JFSS The JFSS was treated with TAaGT at 70 C for 1 h in the presence of 0.1 mmol/L genistin so that the enzyme acted on the partially gelatinized JFSS. The HPLC chromatogram showed that a genistineCA complex was produced (Fig. 7A). The formation of genistineCA was then confirmed by treatment with b-amylase; in the HPLC chromatogram, peaks from 6 upward decreased, whereas peaks 2 and 3 increased (Li et al., 2005). This indicated that the transfer product composed of different (glycosyl)n-genistin complexes hydrolyzed gradually (Fig. 7B). To investigate complex formation between lysolecithin and amylose of the partially gelatinized JFSS, a DSC pan containing the JFSS and lysolecithin was heated and held at 75 C for 15 min. The second DSC run demonstrated that the first peak appearing in the range of 58.4e74.4 C in native starch disappeared completely, whereas the second peak remained, with a slight shift of onset temperature from 79 to 82 C. The peak that appeared in the 100e115 C temperature range represented the lysolecithineamylose complex that was formed between amylose released from the partially gelatinized starch and lysolecithin (Fig. 2D). However, in the case of pretreatment with genistin and TAaGT at 70 C, the onset and conclusion temperatures were shifted to 88.7 C and 97.8 C, respectively (Fig. 2E). These unimodal endothermic peaks might include genistineCA complex and ungelatinized starch. The peak melting temperature of the lysolecithineamylose complex was 106.7 C, whereas that of genistineCA was 92.7 C. The difference in the peak melting temperature of the inclusion complex was presumably due to the interaction between host and guest molecules and also the status of the complexes. The genistin-CA complex could protect of the guest molecule from oxidation, heat, and low pH in a food matrix and may prevent its early release in the gastrointestinal tract, as reported by Cohen, Orlova, Kovalev, Ungar, and Shimoni (2008).
3.9. Water sorption isotherm of partially gelatinized JFSS Water sorption isotherms of native, partially gelatinized, and genistineCA complex-containing JFSS are shown in Fig. 8. The shapes of all four sorption isotherms belonged to the category of type II isotherm among Brunauer's five basic forms of adsorption isotherms. Many biological and food materials shows this pattern of isotherm that can be characterized using BET or GAB models (Roos, 1995). At low water activity region (<0.3), the equilibrium moisture content of the partially gelatinized JFSS was not different from that of native starch. However, in the region of high water activity (>0.4), the equilibrium moisture content of the products containing
Fig. 8. Sorption isotherm of JFSS samples. , native starch; , partially gelatinized starch; , partially gelatinized starch with genistin; , partially gelatinized starch with genistin treated with TAaGT.
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partially gelatinized starch was significantly higher than that of native starch. For instance, at 15 g water/100 g total (general dry products), the partially gelatinized starch products had water activity of ~0.6 significantly lower than that of the native starch (~0.8). The partial gelatinization process could be a useful technology to lower the water activity of food or pharmaceutical products without adding sweetness. It should also be stressed that, if exposed to the same relative humidity (water activity), the partially gelatinized JFSS would adsorb or absorb more moisture to give a higher equilibrium moisture content. 3.10. Conclusions The Vietnamese JFSS had a high amylose content and fairly low amylopectin average chain length. Due to its unique molecular structure, the gelatinized JFSS formed a highly soft and elastic gel. The JFSS showed two separate DSC endotherms of similar enthalpies. The partial gelatinization of the JFSS at 70 C completely removed the first endotherm while maintaining relatively high crystallinity and granular integrity. The partially-gelatinized JFSS showed only a slight change in pasting profile compared to that of the native JFSS. Additionally, the partially-gelatinized JFSS was successfully used to enzymatically produce genistinecycloamylose (CA) complex. Water sorption isotherms of the partially gelatinized JFSS showed higher water-holding capacity than that of the native starch. Unique physicochemical properties of the Vietnamese JFSS and the temperature-controlled partial gelatinization of the JFSS could benefit various industries searching for new starch materials. Acknowledgments This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF-2012R1A2A2A01014594). References Abbas, K. A., Khalil, S. K., & Hussin, A. S. M. (2010). Modified starches and their usages in selected food products: a review study. Journal of Agricultural Science, 2, 90e100. Bobbio, F. O., El-Dash, A. A., Bobbio, P. A., & Rodrigues, L. R. (1978). Isolation and characterization of the physicochemical properties of the starch of jackfruit seeds (Artocarpus heterophyllus). Cereal Chemistry Journal, 55, 505e511. Chung, J. H., Han, J. A., Yoo, B., Seib, P. A., & Lim, S. T. (2008). Effects of molecular size and chain profile of waxy cereal amylopectins on paste rheology during retrogradation. Carbohydrate Polymers, 71, 365e371. Chung, H. J., Lim, H. S., & Lim, S. T. (2006). Effect of partial gelatinization and retrogradation on the enzymatic digestion of waxy rice starch. Journal of Cereal Science, 43, 353e359. Cohen, R., Orlova, Y., Kovalev, M., Ungar, Y., & Shimoni, E. (2008). Structural and functional properties of amylose complexes with genistein. Journal of Agricultural and Food Chemistry, 56, 4212e4218. Dutta, H., Paul, S. K., Kalita, D., & Mahanta, C. L. (2011). Effect of acid concentration and treatment time on acidealcohol modified jackfruit seed starch properties. Food Chemistry, 128, 284e291. Hanashiro, I., Abe, J. I., & Hizukuri, S. (1996). A periodic distribution of the chain length of amylopectin as revealed by high-performance anion-exchange chromatography. Carbohydrate Research, 283, 151e159. Hermansson, A. M., & Svegmark, K. (1996). Developments in the understanding of starch functionality. Trends in Food Science & Technology, 7, 345e353.
Hizukuri, S. (1985). Relationship between the distribution of the chain length of amylopectin and the crystalline structure of starch granules. Carbohydrate Research, 141, 295e306. James, O., & Friday, E. T. (2010). Phytochemical composition, bioactivity and wound healing potential of Euphorbia heterophylla (Euphorbiaceae) leaf extract. International Journal of Pharmaceutical Biomedical Research, 1, 54e63. Jane, J. L., & Chen, J. F. (1992). Effect of amylose molecular size and amylopectin branch chain length on paste properties of starch. Cereal Chemistry, 69, 60e65. Juliano, B. O. (1971). A simplified assay for milled-rice amylose. Cereal Science Today, 16, 334e338. Kabir, S. (1998). Jacalin: a jackfruit (Artocarpus heterophyllus) seed-derived lectin of versatile applications in immunobiological research. Journal of Immunological Methods, 212, 193e211. Kittipongpatana, O. S., & Kittipongpatana, N. (2011). Preparation and physicochemical properties of modified jackfruit starches. LWT e Food Science and Technology, 44, 1766e1773. Kumar, S., Singh, A. B., Abidi, A. B., Upadhyay, R. G., & Singh, A. (1988). Proximate composition of jackfruit seeds. Journal of Food Science and Technology, 25, 141e152. Li, W., Cao, F., Fan, J., Ouyang, S., Luo, Q., Zheng, J., et al. (2014b). Physically modified common buckwheat starch and their physicochemical and structural properties. Food Hydrocolloids, 40, 237e244. Li, D., Roh, S. A., Shim, J. H., Mikami, B., Baik, M. Y., Park, C. S., et al. (2005). Glycosylation of genistin into soluble inclusion complex form of cyclic glucans by enzymatic modification. Journal of Agricultural and Food Chemistry, 53, 6516e6524. Li, S., Zhang, Y., Wei, Y., Zhang, W., & Zhang, B. (2014a). Thermal, pasting and gel textural properties of commercial starches from different botanical sources. Bioprocessing Biotechniques, 4, 100016. Loisel, C., Maache-Rezzoug, Z., Esneault, C., & Doublier, J. L. (2006). Effect of hydrothermal treatment on the physical and rheological properties of maize starch. Journal of Food Engineering, 73, 45e54. Lu, Z. H., Sasaki, T., Li, Y. Y., Yoshihashi, T., Li, L. T., & Kohyama, K. (2009). Effect of amylose content and rice type on dynamic viscoelasticity of a composite rice starch gel. Food Hydrocolloids, 23, 1712e1719. Mukprasirt, A., & Sajjaanantakul, K. (2004). Physico-chemical properties of flour and starch from jackfruit seeds (Artocarpus heterophyllus Lam.) compared with modified starches. International Journal of Food Science & Technology, 39, 271e276. Park, J. H., Kim, H. J., Kim, Y. H., Cha, H., Kim, Y. W., Kim, T. J., et al. (2007). The action mode of Thermus aquaticus YT-1 4-a-glucanotransferase and its chimeric enzymes introduced with starch-binding domain on amylose and amylopectin. Carbohydrate Polymers, 67, 164e173. rez, S., & Bertoft, E. (2010). The molecular structures of starch components and Pe their contribution to the architecture of starch granules: a comprehensive re€rke, 62, 389e420. view. Starch/Sta Rengsutthi, K., & Charoenrein, S. (2011). Physico-chemical properties of jackfruit seed starch (Artocarpus heterophyllus) and its application as a thickener and stabilizer in chilli sauce. LWT e Food Science and Technology, 44, 1309e1313. Roos, Y. H. (1995). Phase transitions in foods. San Diego: Academic Press Inc (Chapter 4). Singh, A., Kumar, S., & Singh, I. S. (1991). Functional properties of jackfruit seed flour. Lebensmittel-Wissenschaft und-Technologie, 24, 373e374. Song, Y., & Jane, J. (2000). Characterization of barley starches of waxy, normal, and high amylose varieties. Carbohydrate Polymers, 41, 365e377. Tongdang, T. (2008). Some properties of starch extracted from three Thai aromatic €rke, 60, 199e207. fruit seeds. Starch/Sta Tran, P. L., Lee, J. S., & Park, K. H. (2013). Molecular structure and rheological character of high-amylose water caltrop (Trapa bispinosa Roxb.) starch. Food Science and Biotechnology, 22, 979e985. Tulyathan, V., Tananuwong, K., Songjinda, P., & Jaiboon, N. (2002). Some physicochemical properties of jackfruit (Artocarpus heterophyllus Lam) seed flour and starch. Science Asia, 28, 37e41. Won, S. Y., Choi, W. S., Lim, H. S., Cho, K. Y., & Lim, S. T. (2000). Viscoelasticity of cowpea starch gels. Cereal Chemistry, 77, 309e314. jean, S., Blanchard, E., Jeantet, R., & Schuck, P. (2011). Prediction of dry Zhu, P., Me mass glass transition temperature and the spray drying behaviour of a concentrate using a desorption method. Journal of Food Engineering, 105, 460e467.
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Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch Phuong Lan Tran a, b, Dang Hai Dang Nguyen a, Viet Ha Do c, Young-Lim Kim c, Sunghoon Park d, Sang-Ho Yoo e, Suyong Lee e, Yong-Ro Kim c, * a
Department of Foodservice Management and Nutrition, Sangmyung University, Seoul, 110-743, Republic of Korea Department of Food Technology, An Giang University, An Giang, 076, Viet Nam Center for Food and Bioconvergence, Department of Biosystems and Biomaterials Science and Engineering, Seoul National University, Seoul, 151-742, Republic of Korea d Institute of Life Sciences and Resources and Graduate School of Biotechnology, Kyung Hee University, Yongin, 446-701, Republic of Korea e Department of Food Science and Technology, Sejong University, Seoul, 143-747, Republic of Korea b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 September 2014 Received in revised form 30 January 2015 Accepted 30 January 2015 Available online xxx
Jackfruit seed starch (JFSS) cultivated in Vietnam had a high amylose content (~44%). Differential scanning calorimetry thermogram of JFSS consisted of two separate endothermic peaks with distinct onset and conclusion temperatures. When JFSS was heated at 70 C, the first endothermic peak disappeared, whereas the second endotherm remained. The partially-gelatinized JFSS still possessed Atype X-ray diffraction pattern. SEM images showed that the rim of the starch granule at the hollow bottom of the bell shape first melted during the partial gelatinization at 70 C. Both native and partiallygelatinized JFSS produced soft and highly elastic gels, but their moduli differed slightly. Additionally, the partially-gelatinized JFSS was successfully used to produce genistinecycloamylose (CA) and amylose elysolecithin complexes with and without 4-a-glucanotransferase. Water sorption isotherms of partially gelatinized JFSS showed higher water-holding capacity than that of the native starch. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Jackfruit (Artocarpus heterophyllus Lam.) seed starch Partial gelatinization Differential scanning calorimetry Dynamic rheological properties Microstructures
1. Introduction Jackfruit (Artocarpus heterophyllus Lam.), which is widely cultivated in tropical countries including Vietnam, has edible bulbs of yellow flesh and seeds. Jackfruit seeds (8e15% of the total fruit weight) have fairly high carbohydrate and protein contents (Bobbio, El-Dash, Bobbio, & Rodrigues, 1978; Kabir, 1998; Kumar, Singh, Abidi, Upadhyay, & Singh, 1988; Singh, Kumar, & Singh, 1991). Jackfruit seeds also contain many minerals, lignans, isoflavones, saponins, and phytonutrients (James & Friday, 2010). Thus, jackfruit seeds are used as ingredients in many culinary preparations. The granules of jackfruit seed starch (JFSS) have bell shape and a smooth surface; the granule size ranges from 5 to 10 mm (Kittipongpatana & Kittipongpatana, 2011). JFSS has great potential in the food industry, especially for use as a thickener, stabilizer, and binding agent (Rengsutthi & Charoenrein, 2011).
* Corresponding author. Tel.: þ82 2 880 4607. E-mail address: [email protected] (Y.-R. Kim).
Recently, there have been several studies on the physicochemical properties of JFSS (Kittipongpatana & Kittipongpatana, 2011; Mukprasirt & Sajjaanantakul, 2004; Rengsutthi & Charoenrein, 2011; Tulyathan, Tananuwong, Songjinda, & Jaiboon, 2002). However, the properties of its different varieties appear to vary. Modified starches have been prepared by various techniques, such as enzymatic, chemical, and physical treatments and partial gelatinization, and have been used widely in the food and pharmaceutical industries (Abbas, Khalil, & Hussin, 2010). There are many processes for starch modification, one of which is hydrothermal treatment (Chung, Lim, & Lim, 2006). Traditionally, the preparation of partially-gelatinized starch was carried out with heat treatment of varying duration at the gelatinization temperature of the relevant starch. The characteristics of the resulting products varied, depending on the processing parameters such as the processing time and temperature. Difficulties in controlling the processing may lead to a degree of gelatinization that is higher than planned or desirable for the product. Partial gelatinization of starch provides a mixture of the properties of both native and fully gelatinized starches. Thus, partially-gelatinized
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starch has been used as a binder and disintegrant. Moreover, after partial gelatinization treatment, starch transforms from an amorphous state to a more ordered or crystalline state that has different digestion properties, providing benefits for the dietary management of metabolic disorders (Chung et al., 2006). Preliminary tests of JFSS gelatinization indicated that it had unique gelatinization characteristics, with two endothermic peaks, each with a distinct onset temperature, which might make it possible to produce a product with unique qualities through temperature-controlled thermal processing. In this study, native and partially gelatinized Vietnamese JFSS were investigated to better understand their physicochemical properties and potential uses. 2. Materials and methods
connected in tandem and equilibrated at room temperature. The molecular weight of the samples was analyzed using the ASTRA software (ver. 4.90.07; Wyatt Technology), and the Berry extrapolation method was used for curve fitting with a dn/dc value of 0.146 mL/g. 2.4. Purification of thermostable 4-a-glucanotransferase (TAaGT) enzyme The 4-a-glucanotransferase gene, cloned by Park et al. (2007), encoded the TAaGT enzyme. The plasmid was expressed in E. coli MC1061, and the target enzyme was isolated using a nickelnitrilotriacetic acid (Ni-NTA) column (Qiagen, Hilden, Germany) (Park et al., 2007). The purity of TAaGT enzymes was confirmed by SDS-PAGE.
2.1. Isolation of starch Jackfruit seeds were purchased at a local market in An Giang, Vietnam. The seeds were washed, and the white aril was peeled off. Next, the thin brown spermoderm covers were removed following the method of Tulyathan et al. (2002). The JFSS was isolated by wetpowdering the raw material with 0.05 mol/L aqueous NaOH, screening the slurry through a 100-mm testing sieve, and subjecting it to centrifugation (8000 g, 15 min). The sediment was resuspended in distilled water and centrifuged again. The raw starch was washed four times with two volumes of ethanol to completely remove organic-soluble components, especially lipids, and was then washed several times more with distilled water until the starch was free of color. The starch was dried in an air oven at 40 ± 1 C until the final moisture content was <13%. 2.2. Isolation of amylose and amylopectin Amylose and amylopectin were isolated following the method of Song and Jane (2000) with slight modifications. The starch slurry (13.3 g/L) was heated and stirred in a water bath at 96 C for 1 h. The starch solution was filtered to remove insoluble residues, adjusted to pH 6.3 with phosphate buffer, autoclaved at 121 C for 1 h, and then boiled and stirred at 96 C for 2 h to disperse the starch molecules. One fifth volume of n-butyl alcohol was then added to the starch solution. The solution was cooled to room temperature over a period of 24e36 h. The amyloseebutyl alcohol complex crystals that formed and precipitated during cooling were separated by centrifugation (8700 g, 30 min). The solution was treated twice more with n-butyl alcohol to obtain residual amylose. The amylopectin remaining in the supernatant was obtained by precipitation with at least two volumes of ethanol, followed by centrifugation. The amylose content of the native starch of jackfruit seed was measured colorimetrically using Juliano's method (Juliano, 1971) based on amyloseeiodine complex formation, as described by Tran, Lee, and Park (2013). 2.3. Size exclusion chromatography-multi-angle laser scatteringrefractive index detection (SEC-MALLS-RI)
2.5. Preparation of partially gelatinized starch The JFSS was dispersed in distilled water (weight ratio of 3:7) at room temperature. Each batch of dispersion was heated and shaken at 70 C for 20, 30, or 60 min. The partially-gelatinized starch was cooled, and a double volume of ethanol was added with continuous stirring. Ethanol was then removed by centrifugation. The partially gelatinized JFSS was dried in an oven at 40 ± 1 C for 24 h and used for further analysis.
2.6. High-performance anion exchange chromatography (HPAEC) The amylopectin branch chains of the native and modified samples were debranched with isoamylase (Hyashibara Biochemical Labs, Okayama, Japan) in 50 mmol/L sodium acetate buffer (pH 4.3) at 60 C for 72 h. The amylopectin branch chain length distribution was analyzed using an HPAEC system (Dionex-300, Dionex, Sunnyvale, CA, USA) with a pulsed amperometric detector (ED40, Dionex). The system was equipped with a CarboPac PA-1 anion exchange column (4 250 mm, Dionex). The sample was eluted with a 10e70% (v/v) gradient of 600 mmol/L sodium acetate in 150 mmol/L sodium hydroxide at a flow rate of 1.0 mL/min (Park et al., 2007).
2.7. High-performance liquid chromatography (HPLC) The genistineCA complex formation of the JFSS treated with TAaGT in the presence of genistin was determined using a Waters 600S HPLC system with a 150 3.9-mm i.d. Nova-Pak C18 column and an SLC 200 UVevis detector (Samsung, Seoul, Korea) set at 254 nm. For the gradient solvent system, solvent A (water/formic acid, 100:0.1, v/v) and solvent B (100% acetonitrile) were used, with solvent B increasing gradually from 10 to 50% during a 20-min interval at a flow rate of 1 mL/min.
2.8. Differential scanning calorimetry (DSC) Amylose and amylopectin of the JFSS were dissolved in 1 mol/L NaOH at 75 C and then neutralized with 1 mol/L HCl and diluted with 50 mmol/L NaNO3 to a final concentration of 5 g/L. The molecular weights of amylose and amylopectin were determined by SEC-MALLS (Dawn DSP, Wyatt Technology, Santa Barbara, CA, USA, and Waters 410, Bedford, MA, USA) at a constant flow rate of 0.4 mL/min in 100 mmol/L NaNO3 containing 0.2 g/L NaN3. Two columns, a Shodex OHpak SB-806 HQ (8.0 300 mm; Showa Denko) and a YMC-Pack-Diol 120G (8.0 300 mm; YMC), were
The thermal properties of the native and modified JFSS were determined using DSC (Seiko Instruments [SII] SSC/5200, Tokyo, Japan) after calibration with indium (156.6 C, 28.59 J/g) and tin (232.2 C, 60.62 J/g). A 2.5 mg sample and 7.5 mL distilled water were sealed hermetically in an aluminum pan. DSC thermogram was obtained while the pan was heated from 30 to 160 C at 10 C/ min. The test was carried out with a pan filled with distilled water as a reference, and analyses were performed in triplicate.
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2.9. Rheological and pasting properties The paste/gel characteristics of the starch were determined using a dynamic rheological test, as described by Tran et al. (2013). The starch paste samples (5% starch content) heated in a boiling water bath for 30 min with stirring were loaded into a rheometer between parallel 40-mm diameter plates at a gap distance of 1 mm. After trimming off the overloaded portion of sample around the plates, a thin layer of silicon oil was applied to the open side of the sample to prevent moisture loss. A solvent trap was also used to minimize water loss during the measurements. All the measurements were conducted at 1% strain, which was within the linear viscoelastic region (data not shown). A time sweep test was conducted at a fixed frequency of 1 Hz by recording the storage (G0 ) and loss (G00 ) moduli continuously at 4 C as a function of time over 2 h. At the end of the gelation period, frequency sweep tests were performed over the range of 0.1e10 Hz. The pasting properties of the native and partially gelatinized JFSS were investigated using a Rapid Visco Analyzer (RVA 3D, Newport Scientific, Warriewood NSW, Australia). Samples of starch (3 g, 11.2% moisture content) were dispersed in 25 g distilled water in an aluminum canister. The starch slurry was initially mixed and then held at 50 C for 2 min, heated to 95 C at 12 C/min, held at 95 C for 2 min 30 s, cooled to 50 C, and finally held at 50 C for 2 min at 160 rpm. The parameters analyzed were pasting temperature, peak viscosity, final viscosity, breakdown viscosity, and setback viscosity. 2.10. Scanning electron microscopy (SEM) The samples were coated with gold using a magnetron sputter coater (Jeol, MSC-101) before being observed with the SEM (Jeol, JSM-5600LV) with a large field detector. The acceleration voltage was 5e15 kV under low vacuum mode (0.7e0.8 torr). Pictures were captured using automatic image capture software (SEM Control User Interface, ver. 2.11). 2.11. X-ray diffractometry (XRD) The XRD patterns were recorded using a powder X-ray diffractometer (D8 Advance, Bruker, Karlsruhe, Germany) with Cu-Ka radiation (l ¼ 1.5406 Å) and crystal graphite monochromator applied at a voltage of 40 kV and a 45 mA current. All the samples were analyzed in the 2q angle range of 5 e40 , and process parameters were set as follow: scan step size, 0.02 (2q); scan step time, 1 s.
known water activities (LiCl-0.11, K2CO3-0.48, NaCl-0.75, BaCl2jean, Blanchard, Jeantet, & Schuck, 2011). 0.90) at 25 C (Zhu, Me The samples were allowed to equilibrate for approximately 10 days until there was no discernible weight change (±0.001 g). The equilibrium moisture contents were measured and plotted against water activities of different salt solutions in desiccators. Each experiment was conducted in triplicate. 3. Results and discussion 3.1. Content and molecular weight of the amylose and amylopectin in the JFSS The JFSS from Vietnam had a relatively high apparent amylose content of 43.96%, compared to previously reported amylose contents of various JFSS cultivars from different regions (Bobbio et al., 1978; Dutta, Paul, Kalita, & Mahanta, 2011; Kittipongpatana & Kittipongpatana, 2011; Mukprasirt & Sajjaanantakul, 2004; Tongdang, 2008; Tulyathan et al., 2002). The molecular weights of amylose and amylopectin of the JFSS were measured to be (5.13 ± 0.36) 106 g mol1 and (2.22 ± 0.02) 107 g mol1, respectively, which were similar to those of water caltrop starch (Tran et al., 2013) and within the average ranges for amylose and amylopectin of cereal starches, while those of other JFSS varieties were not reported yet. Chung, Han, Yoo, Seib, and Lim (2008) and Jane and Chen (1992) reported that the molecular weight of amylose and amylopectin and amylopectin branch chain length had effects on the pasting properties of starches. 3.2. Amylopectin branch chain length distribution of the JFSS The amylopectin branch chain length distribution pattern of the JFSS was somewhat broad, with the highest peak at DP 13 and a shoulder at DP 18 (Fig. 1). Considering that the average chain length rez & (CL) of most amylopectins lies in the range of 17e26 (Pe Bertoft, 2010), the JFSS amylopectin had a fairly short average CL of 18.05. As suggested by Hanashiro, Abe and Hizukuri (1996), the amylopectin branch chains of the JFSS, up to approximately DP 60, was classified in four fractions: A, B1, B2, and B3 chains (Fig. 1). The proportion of A chain (DP 6e12) was 24.98%. The amount of this group has been correlated with the crystallinity type and average CL for various amylopectin samples (Hizukuri, 1985). Due to the short average CL, the JFSS had high A chain content in A-crystalline material. The amount of B1 chain (DP 13e24) was highest (50.10%), and the proportions of the B2 chain (DP 25e36) and B3 chain
2.12. Enzymatic modification of the JFSS supplemented with genistin
2.13. Moisture sorption isotherm Native JFSS, partially-gelatinized JFSS, partially-gelatinized JFSS with genistin, and partially-gelatinized JFSS with genistin treated with TAaGT, respectively, were weighted (0.5 ± 0.001 g) in disposable aluminum dishes (57 mm diameter) and placed inside desiccators that contained different saturated salt solutions with
5
B1
A
B2
B3
4
Relative peak area (%)
The JFSS was dispersed in 50 mmol/L TriseHCl buffer (pH 7.5) at a ratio of 1:3 and supplemented with genistin at a final concentration of 0.1 mM. The mixture was then treated with TAaGT (0.05 U/mg of substrate) at 70 C for 1 h. For the detection of the CAegenistin complex, the reaction mixture was treated with bamylase from Bacillus cereus using 0.3 U/mL of reaction mixture for 1 h at 40 C.
3
3
2
1
0 10
20
30
40
50
60
Degree of polymerization (DP)
Fig. 1. Branch chain length distribution of the JFSS amylopectin. A, DP 6e12; B, DP 12e24; B2, DP 25e36; and B3, DP > 37.
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(DP > 37) were 14.56% and 10.36%, respectively. Additionally, the area percentages of DPs in the A chain fraction were high in comparison with the other fractions (Fig. 1) and other starches (Hizukuri, 1985). 3.3. Thermal properties of native and partially gelatinized JFSS Thermal properties of the native and partially gelatinized JFSS (at 70 C for 1 h) were analyzed by DSC. The JFSS demonstrated two distinguishable endothermic peaks with distinct onset, peak, and conclusion temperatures: To ¼ 58.4 C, Tp ¼ 66.4 C for peak I and To ¼ 79 C, Tp ¼ 82.7 C for peak II (Table 1 and Fig. 2A). In contrast, JFSS from Thailand displayed only one endothermic peak (Kittipongpatana & Kittipongpatana, 2011; Mukprasirt & Sajjaanantakul, 2004; Tongdang, 2008). Both endothermic peaks completely disappeared when the sample was rescanned after heating up to 120 C (Fig. 2B), indicating that both endotherms were gelatinization peaks. When the JFSS sample was heat-treated at 70 C for 1 h, cooled to room temperature, and rescanned, the peak I completely disappeared and the endothermic peak II remained (Fig. 2C and Table 1). The results implied that the heat treatment at 70 C gelatinized a part of the JFSS whereas the rest parts remained ungelatinized. This also implied that there might be two different groups of crystalline structure that were located in either different starch granules or different compartments of the same granule. The degree of gelatinization of the partiallygelatinized JFSS, estimated from gelatinization enthalpies in Table 1, was approximately 53%.
The starch granules became more concave and wrinkled during heat processing (Fig. 3 BeD). At 70 C, starch granules did not show noticeable swelling, whereas amylose continuously leached out to cover starch granules and finally form lumps (Fig. 3D). 3.5. Pasting properties of native and partially gelatinized JFSS Pasting properties of the JFSS are summarized in Table 2 and compared with those of other starches previously reported. Even though pasting properties, especially peak viscosity, depend on experimental conditions such as solids content, direct comparison of published data in Table 2 requires extreme caution. This notwithstanding, some differences in the pasting properties of the JFSS were observed compared to other starches. The pasting temperature of the JFSS (64.2 C) was relatively low, just above that of potato starch (63.0 C), whereas peak viscosity was relatively high (3.8 Pa.s). Also, the final viscosity and setback of the JFSS were significantly high (5.2 Pa.s and 2.4 Pa.s, respectively), suggesting that the JFSS formed a highly viscous paste capable of forming a solid gel network. The pasting temperature and peak viscosity of partially gelatinized JFSS was slightly lower than that of the native starch. However, the partially gelatinized JFSS had higher final viscosity and setback values compared to those of the native sample (Table 2). Pasting profile depicted in Fig. 4 might provide
3.4. SEM image analysis of partially gelatinized JFSS The JFSS granules had mainly bell shapes and hollow bottoms, similar to other varieties of JFSS described in previous reports (Fig. 3A: arrow a) (Bobbio et al., 1978; Kittipongpatana & Kittipongpatana, 2011; Tongdang, 2008). The JFSS granular morphologies changed with heat treatment time at 70 C (20, 30, and 60 min) (Fig. 3 BeD). The outermost layers at the bottom of the bellshaped granules were hydrated, making the surface of the granules less smooth (Fig. 3B: arrow b), with the rim of the bell-shaped granules melting first probably due to the large specific surface (Fig. 3 BeC: arrow b) and faster penetration of water molecules. This might result in a low onset temperature of 59 C (peak I, Fig. 2A), whereas the upper part of the granule might gelatinize at a higher temperature, 79 C (peak II, Fig. 2A). However, this is a rough postulation based on qualitative microscopic observations. More intensive investigation will be required to clarify the above claims.
Table 1 Thermal properties of the native and modified JFSS. Native Peak 1 To ( C) Tp ( C) Tc ( C) DH (J g1) Peak 2 To ( C) Tp ( C) Tc ( C) DH (J g1) Peak 3 To ( C) Tp ( C) Tc ( C) DH (J g1)
58.4 66.4 74.3 5.64 79.0 82.7 88.5 5.68 e e e e
± ± ± ± ± ± ± ±
Partial Complex with GenistineCA gelatinizationa lysolecithin complex 0.26 0.10 0.30 0.05 0.20 0.10 0.27 0.02
e e e e 79.0 83.3 88.1 5.33 e e e e
± ± ± ±
0.15 0.20 0.00 0.01
e e e e 82.0 ± 0.17 84.8 ± 0.10 89.8 ± 0.10 6.59 ± 0.03 99.7 ± 0.10 106.7 ± 0.10 112.9 ± 0.00 5.23 ± 0.01
e e e e e e e e 88.7 92.7 97.8 8.05
± ± ± ±
0.20 0.25 0.10 0.01
To, onset temperature; Tp, peak temperature; Tc, conclusion temperature; e, not detected. a Partially gelatinized at 70 C for 1 h.
Fig. 2. Thermal property analysis of the JFSS samples. (A) Native JFSS, (B) native JFSS scanned a second time, (C) partially gelatinized JFSS, (D) mixture of partially gelatinized JFSS with lysolecithineamylose complex, (E) mixture of partially gelatinized JFSS with genistineCA complex.
Please cite this article in press as: Tran, P. L., et al., Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch, LWT - Food Science and Technology (2015), http://dx.doi.org/10.1016/j.lwt.2015.01.054
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Fig. 3. Scanning electron microscopy (SEM) images of (A) native JFSS and (B), (C), and (D) partially gelatinized JFSS at 70 C for 20, 30, or 60 min, respectively. Arrow a: concave and hollow region; arrow b: rough surface and partially gelatinized region; arrow c: ungelatinized granule partially covered with partially gelatinized starch.
some points to discuss in comparison with DSC thermograms (Fig. 2) and SEM micrograms (Fig. 3). The native JFSS showed a shoulder at the beginning of viscosity increase, which could indicate the existence of two different melting temperatures as seen in the DSC thermogram (Fig. 2A). As for the partially-gelatinized starch, the initial viscosity was slightly higher than that of control probably due to the partial amylose leaching and minor swelling of starch granules as evidenced in Fig. 3 and the viscosity increase was rather gradual making the shoulder less obvious. During the stage of the sharpest viscosity increase after the shoulder or gradual increase, both graphs overlapped, implying that swelling of starch granules was mainly governed by the second melting at above 80 C (Figs. 2 A and C). The fact that starch granules did not swell significantly after the heat treatment at 70 C (Fig. 3) could support this. As a result, partial gelatinization of the JFSS at 70 C converted
the gelatinization profile from bi-modal to uni-modal and modified the pasting profile that were characterized as lower breakdown thus improved stability and higher final viscosity. 3.6. Rheological properties of the JFSS Immediately after preparing native and partially-gelatinized JFSS paste samples (5% starch content) by heating in a boiling water bath for 1 h, respectively, dynamic rheological properties were measured at 4 C over time to investigate their gelation characteristics (Fig. 5 top). Both native and partially-gelatinized JFSS paste samples showed a relatively rapid increase in G0 and an almost constant G00 , thus a rapid decrease in d down to ~5 during the initial 50 min of gelation period at 4 C. Frequency sweep test conducted at the end of 2 h gelation period (Fig. 5 bottom) revealed
Table 2 Pasting properties of JFSS in comparison with other starches. Starch
Pasting temp. ( C)
Jackfruit seeda Partially gelatinized JFSSa,b Wheat Sweet potato Cassava Buckwheat Water caltrop Cowpea Acorn Corn Potato
64.2 58.7 66.5 66.9 68.4 _ 75.0 76.0 77.0 81.0 63.0
a b
± ± ± ± ±
0.07 0.06 0.07 0.30 0.10
± ± ± ± ±
0.00 0.00 0.00 0.00 0.00
Peak viscosity (Pa.s) 3.8 3.3 0.4 0.9 1.2 4.6 3.0 1.7 1.3 1.2 7.6
± ± ± ± ± ± ± ± ± ± ±
0.01 0.08 0.01 0.01 0.01 0.04 0.00 0.00 0.00 0.00 0.00
Breakdown (Pa.s) 1.3 0.9 0.2 0.5 0.7 2.4 1.0 0.6 0.5 0.4 6.0
± ± ± ± ± ± ± ± ± ± ±
0.02 0.01 0.02 0.00 0.00 0.04 0.00 0.00 0.00 0.00 0.00
Final viscosity (Pa.s) 5.2 5.5 0.5 0.6 0.7 0.4 6.5 2.2 1.5 1.2 2.5
± ± ± ± ± ± ± ± ± ± ±
0.06 0.05 0.02 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00
Setback (Pa.s) 2.4 2.8 0.3 0.5 0.8 1.8 4.5 1.1 0.8 0.5 0.8
± ± ± ± ± ± ± ± ± ± ±
0.05 0.08 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00
Reference This study This study (Li, Zhang, Wei, Zhang & Zhang, 2014) (Li, Zhang, Wei, Zhang & Zhang, 2014) (Li, Zhang, Wei, Zhang & Zhang, 2014) (Li et al., 2014) (Tran et al., 2013) (Won, Choi, Lim, Cho, & Lim, 2000) (Won et al., 2000) (Won et al., 2000) (Won et al., 2000)
Data are averages of triplicate values. Partially gelatinized at 70 C for 1 h.
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Fig. 4. Pasting profile of (A) native and (B) partially gelatinized JFSS (10% starch content). A dotted line represents temperature program.
that G0 was almost independent of frequency maintaining fairly large different between G0 and G00 . The frequency independency and low phase angle indicated the JFSS gel was highly “solid-like (elastic)”. Generally, the amylose content of starch affects the
dynamic viscoelasticity of starch gel: starch with high amylose content normally shows high G0 (Lu et al., 2009). Even though the JFSS paste formed a solid gel after 50 min at 4 C, the G0 of the JFSS gel was surprisingly low (120e170 Pa) considering its high amylose content (~44%). This was obvious when compared to another high amylose tropical starch, water caltrop starch (amylose content was 47% and G0 of 5% gel formed at 20 C was ~1200 Pa) (Tran et al., 2013), and even to maize starch (amylose content was 27e28% and G0 of 6% gel formed at 25 C was ~800 Pa) (Loisel, MaacheRezzoug, Esneault, & Doublier, 2006). Although amylose content is an important factor for starch gelation, properties of starch dispersion/gel are not simply governed by its composition and molecular structures (Hermansson & Svegmark, 1996). Starch gel properties are determined by various physicochemical interactions such as the formation of continuous phase by leached amylose, aggregation of leached amylose, integrity and space-filling of dispersed swollen granules (Hermansson & Svegmark, 1996). These complex interactions might be modified in the partially-gelatinized JFSS, causing slightly different gel properties compared to those of the native JFSS as shown in Fig. 5. The rheological data obtained in this study were not enough to fully explain the complexity of the JFSS gel. Instead, rather practical information on the JFSS gel, the formation of soft but highly elastic gel, could benefit various industries searching for new starch materials.
3.7. Powder XRD patterns of native and partially gelatinized JFSS Powder XRD patterns of native, partially-gelatinized (at 70 C for 1 h), and fully-gelatinized JFSS were obtained to investigate their crystalline structures (Fig. 6). The native JFSS showed a typical A-type crystallinity pattern with prominent diffraction peaks at Bragg angles (2q) of 15 , 17, 18 , 23 , which was in agreement with previous reports (Kittipongpatana & Kittipongpatana, 2011; Tulyathan et al., 2002). Partial gelatinization of the JFSS at 70 C fairly diminished the crystallinity peaks. However, partial crystallinity with A-type pattern still remained after heat treatment at 70 C, which was more obvious when compared to the XRD pattern of the fully-gelatinized JFSS. Remaining partial crystallinity after heat treatment at 70 C could be related to the relatively wellconserved granular integrity of the partially-gelatinized JFSS without significant swelling as shown in Fig. 3.
Fig. 5. Dynamic rheological properties of the JFSS gel (5% starch content) obtained from time sweep (top) and frequency sweep (bottom) tests at 4 C: (A) G0 of native JFSS, (B) G0 of partially gelatinized JFSS, (C) G00 of native JFSS, (D) G00 of partially gelatinized JFSS, (E) phase angle (d) of native JFSS, (F) d of partially gelatinized JFSS.
Fig. 6. Powder X-ray diffraction patterns of (A) native, (B) partially-gelatinized, and (C) fully-gelatinized JFSS.
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Fig. 7. HPLC analysis of genistineCA complex formation in the partially gelatinized JFSS treated with TAaGT. (A) Before and (B) after b-amylase treatment in which 1, genistin; 2, glycosylegenistin; 3, maltosylegenistin; 4, maltotriosylegenistin; 5, maltotetraosylegenistin; 6, maltopentosylegenistin were added; 7, CA-genistin complex.
3.8. Formation of inclusion complexes with partially gelatinized JFSS The JFSS was treated with TAaGT at 70 C for 1 h in the presence of 0.1 mmol/L genistin so that the enzyme acted on the partially gelatinized JFSS. The HPLC chromatogram showed that a genistineCA complex was produced (Fig. 7A). The formation of genistineCA was then confirmed by treatment with b-amylase; in the HPLC chromatogram, peaks from 6 upward decreased, whereas peaks 2 and 3 increased (Li et al., 2005). This indicated that the transfer product composed of different (glycosyl)n-genistin complexes hydrolyzed gradually (Fig. 7B). To investigate complex formation between lysolecithin and amylose of the partially gelatinized JFSS, a DSC pan containing the JFSS and lysolecithin was heated and held at 75 C for 15 min. The second DSC run demonstrated that the first peak appearing in the range of 58.4e74.4 C in native starch disappeared completely, whereas the second peak remained, with a slight shift of onset temperature from 79 to 82 C. The peak that appeared in the 100e115 C temperature range represented the lysolecithineamylose complex that was formed between amylose released from the partially gelatinized starch and lysolecithin (Fig. 2D). However, in the case of pretreatment with genistin and TAaGT at 70 C, the onset and conclusion temperatures were shifted to 88.7 C and 97.8 C, respectively (Fig. 2E). These unimodal endothermic peaks might include genistineCA complex and ungelatinized starch. The peak melting temperature of the lysolecithineamylose complex was 106.7 C, whereas that of genistineCA was 92.7 C. The difference in the peak melting temperature of the inclusion complex was presumably due to the interaction between host and guest molecules and also the status of the complexes. The genistin-CA complex could protect of the guest molecule from oxidation, heat, and low pH in a food matrix and may prevent its early release in the gastrointestinal tract, as reported by Cohen, Orlova, Kovalev, Ungar, and Shimoni (2008).
3.9. Water sorption isotherm of partially gelatinized JFSS Water sorption isotherms of native, partially gelatinized, and genistineCA complex-containing JFSS are shown in Fig. 8. The shapes of all four sorption isotherms belonged to the category of type II isotherm among Brunauer's five basic forms of adsorption isotherms. Many biological and food materials shows this pattern of isotherm that can be characterized using BET or GAB models (Roos, 1995). At low water activity region (<0.3), the equilibrium moisture content of the partially gelatinized JFSS was not different from that of native starch. However, in the region of high water activity (>0.4), the equilibrium moisture content of the products containing
Fig. 8. Sorption isotherm of JFSS samples. , native starch; , partially gelatinized starch; , partially gelatinized starch with genistin; , partially gelatinized starch with genistin treated with TAaGT.
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partially gelatinized starch was significantly higher than that of native starch. For instance, at 15 g water/100 g total (general dry products), the partially gelatinized starch products had water activity of ~0.6 significantly lower than that of the native starch (~0.8). The partial gelatinization process could be a useful technology to lower the water activity of food or pharmaceutical products without adding sweetness. It should also be stressed that, if exposed to the same relative humidity (water activity), the partially gelatinized JFSS would adsorb or absorb more moisture to give a higher equilibrium moisture content. 3.10. Conclusions The Vietnamese JFSS had a high amylose content and fairly low amylopectin average chain length. Due to its unique molecular structure, the gelatinized JFSS formed a highly soft and elastic gel. The JFSS showed two separate DSC endotherms of similar enthalpies. The partial gelatinization of the JFSS at 70 C completely removed the first endotherm while maintaining relatively high crystallinity and granular integrity. The partially-gelatinized JFSS showed only a slight change in pasting profile compared to that of the native JFSS. Additionally, the partially-gelatinized JFSS was successfully used to enzymatically produce genistinecycloamylose (CA) complex. Water sorption isotherms of the partially gelatinized JFSS showed higher water-holding capacity than that of the native starch. Unique physicochemical properties of the Vietnamese JFSS and the temperature-controlled partial gelatinization of the JFSS could benefit various industries searching for new starch materials. Acknowledgments This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF-2012R1A2A2A01014594). References Abbas, K. A., Khalil, S. K., & Hussin, A. S. M. (2010). Modified starches and their usages in selected food products: a review study. Journal of Agricultural Science, 2, 90e100. Bobbio, F. O., El-Dash, A. A., Bobbio, P. A., & Rodrigues, L. R. (1978). Isolation and characterization of the physicochemical properties of the starch of jackfruit seeds (Artocarpus heterophyllus). Cereal Chemistry Journal, 55, 505e511. Chung, J. H., Han, J. A., Yoo, B., Seib, P. A., & Lim, S. T. (2008). Effects of molecular size and chain profile of waxy cereal amylopectins on paste rheology during retrogradation. Carbohydrate Polymers, 71, 365e371. Chung, H. J., Lim, H. S., & Lim, S. T. (2006). Effect of partial gelatinization and retrogradation on the enzymatic digestion of waxy rice starch. Journal of Cereal Science, 43, 353e359. Cohen, R., Orlova, Y., Kovalev, M., Ungar, Y., & Shimoni, E. (2008). Structural and functional properties of amylose complexes with genistein. Journal of Agricultural and Food Chemistry, 56, 4212e4218. Dutta, H., Paul, S. K., Kalita, D., & Mahanta, C. L. (2011). Effect of acid concentration and treatment time on acidealcohol modified jackfruit seed starch properties. Food Chemistry, 128, 284e291. Hanashiro, I., Abe, J. I., & Hizukuri, S. (1996). A periodic distribution of the chain length of amylopectin as revealed by high-performance anion-exchange chromatography. Carbohydrate Research, 283, 151e159. Hermansson, A. M., & Svegmark, K. (1996). Developments in the understanding of starch functionality. Trends in Food Science & Technology, 7, 345e353.
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Please cite this article in press as: Tran, P. L., et al., Physicochemical properties of native and partially gelatinized high-amylose jackfruit (Artocarpus heterophyllus Lam.) seed starch, LWT - Food Science and Technology (2015), http://dx.doi.org/10.1016/j.lwt.2015.01.054