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Morphology and Characteristics of Starch Nanoparticles Self-Assembled via a

Rapid Ultrasonication Method for Peppermint Oil Encapsulation

Article  in  Journal of Agricultural and Food Chemistry · August 2017

DOI: 10.1021/acs.jafc.7b02938

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* UNKNOWN * | MPSJCA | JCA10.0.1465/W Unicode | jf-2017-02938a.3d (R3.6.i12 HF02:4458 | 2.0 alpha 39) 2016/10/28 09:46:00 | PROD-JCA1 | rq_9494237 | 9/14/2017 14:03:35 | 11 | JCA-DEFAULT

Article

pubs.acs.org/JAFC

1 Morphology and Characteristics of Starch Nanoparticles

2 Self-Assembled via a Rapid Ultrasonication Method for

3 Peppermint Oil Encapsulation

4 Chengzhen Liu,† Man Li,† Na Ji,† Jing Liu,‡ Liu Xiong,† and Qingjie Sun*,†
†
5 College of Food Science and Engineering, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District,
6 Qingdao, Shandong Province 266109, China
‡
7 Central Laboratory, Qingdao Agricultural University, 700 Changcheng Road, Chengyang District, Qingdao,
8 Shandong Province 266109, China
9 *
S Supporting Information

10 ABSTRACT: Starch nanoparticles (SNPs) and peppermint oil (PO)-loaded SNPs were fabricated via an ultrasonic bottom-up
11 approach using short linear glucan debranched from waxy maize starch. The effects of the glucan concentration, ultrasonic
12 irradiation time, and chain length on the SNPs’ characteristics were investigated. Under the optimal conditions, i.e., short linear
13 glucan concentration of 5% and ultrasonication time of 8−10 min, SNPs were successfully prepared. The as-prepared SNPs
14 showed good uniformity and an almost perfect spherical shape, with diameters of 150−200 nm. The PO-loaded SNPs also
15 exhibited regular shapes, with sizes of approximately 200 nm. The loading capacity, encapsulation efficiency, and yield of
16 PO-loaded SNPs were ∼25.5%, ∼87.7%, and ∼93.2%, respectively. After encapsulation, PO possessed enhanced stability against
17 thermal treatment (80 °C). The pseudo-first-order kinetics model accurately described the slow-release properties of PO from
18 SNPs. This new approach of fabricating SNPs is rapid, high yield, and nontoxic, showing great potential in the encapsulation and
19 sustained release of labile essential oils or other lipids.
20 KEYWORDS: short linear glucan, ultrasonic processing, essential oil, encapsulation

21

22
■ INTRODUCTION
Starch, as a naturally renewable and biodegradable biopolymer,
the nanometer scale after oxidation followed by ultrasonic
treatment for 3 h, with the particle size of SNPs ranging from 20
50
51

23 is one of the most abundant reserve carbohydrates, and it to 60 nm.8 Bel Haaj et al. reported on nanoparticles of 30−250 52

24 constitutes a fundamental material for food and nonfood use.1 nm in size prepared from waxy maize starch granules using a 53

25 Native starch granules exhibit a size of 1−100 μm, making them high-intensity ultrasonication method for more than 75 min.9 54

26 microscale granules. Starch is predominantly composed of linear In the published literature using the ultrasonication method, 55

27 amylose and branched amylopectin. In recent years, nanoscale the SNPs were all fabricated via a top-down process. In such a 56

28 starch particles have drawn considerable attention as novel and process, large starch granules can be gradually broken into nano- 57

29 biofunctional materials in diverse applications, including drug scale particles through a mechanical size-reduction process.10 58

30 (or bioactive substance) delivery carriers,2 film fillers,3 emulsion However, this top-down ultrasonication method consumes a 59

31 stabilizers, and fat replacers.4 In the past few decades, various great deal of energy and still has a long duration, on the time scale 60

32 techniques have been developed for the preparation of starch of hours. Alternatively, the bottom-up approach to preparing 61

33 nanoparticles (SNPs), including acid hydrolysis, mini-emulsion nanoparticles mainly relies on eliciting specific interactions 62

34 cross-linking, enzymatic treatment, and physical treatments.2 between molecules to drive an autonomous self-assembly pro- 63

35 Nevertheless, these methods are associated with environmental cess under appropriate conditions.11 This method makes it easy 64

36 pollution, low yields, or high energy costs.4 Recently, Sun et al. to quickly fabricate uniform nanoparticles compared with the 65

37 proposed a simple, environmentally friendly technique for top-down approach. To the best of our knowledge, there is no 66

38 obtaining SNPs by pullulanase debranching of waxy maize starch information on producing SNPs using a bottom-up approach 67

39 followed by recrystallization.5 Moreover, Qiu et al. developed combined with ultrasonication. 68

40 an easy method of preparing SNPs using nanoprecipitation of The linear unbranched amylose fraction of starch is known to 69

41 debranched waxy corn starch.6 Although these new methods form inclusion complexes with low-molecular-weight substances, 70

42 are green, simple, and scalable, a time-saving technique is still such as iodine, alcohols, lipids, and aromatic compounds.12 Meng 71

43 lacking. et al. prepared starch−palmitic acid complexes through heating 72

44 Ultrasonic technology has also been used to prepare SNPs combined with high pressure homogenization.13 Ocloo et al. 73

45 within a short duration of time. Ultrasonication generates ultra-

46 sonic cavitation in the solution and causes microbubbles. When Received: June 26, 2017
47 microbubbles collapse, high energy is released and converted Revised: August 27, 2017
48 to high pressure and high temperature.7 Sun et al. reported that Accepted: August 29, 2017
49 waxy corn starch granules are converted from the micrometer to Published: August 29, 2017

© XXXX American Chemical Society A DOI: 10.1021/acs.jafc.7b02938

J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

74 reported that amylose−lipid complexes are formed during S-SLG, or L-SLG powders were dispersed in ultrapure water with 120
75 pasting of high amylose maize starch with stearic acid under various concentrations (1, 5, and 10%, w/v, respectively) and autoclaved 121
76 pressure.14 Moreover, Qiu et al. reported that essential oils are at 121 °C. After cooling to room temperature, each aqueous solution 122
was irradiated with a high-intensity ultrasonic horn (JY 92-IIN, 123
77 encapsulated in SNPs prepared by short glucan chains.15 Natural
20−25 kHz, 990 W/cm2) operating at 10% efficiency for different 124
78 essential oils, a concentrated aromatic hydrophobic liquid, are lengths of time (5, 8, and 10 min). The formed nanoparticle suspension 125
79 widely used in perfumes, cosmetics, food and drink, and was allowed to cool to room temperature to determine the morphology 126
80 medicines. However, low water solubility, high volatility, and and particle size. The suspension was centrifuged at 10,000 g for 10 min, 127
81 strong odor limit their applications.16 To overcome these and then the sediments were lyophilized for 48 h to obtain dry powders. 128
82 drawbacks, various encapsulation techniques have been studied. For the preparation of PO-loaded SNPs, the cooked SLG solution 129
83 Lv et al. have prepared jasmine essential oil nanocapsules by (5%, w/v) containing PO (4.5% w/w, percentage of SLG) was irradiated 130
84 gelatin and gum arabic based complex coacervation.17 de Oliveira with a high-intensity ultrasonic horn for 8 min (primary SLG and 131

85 et al. have successfully fabricated nanoparticles of alginate/ L-SLG) or 10 min (S-SLG). The nanoparticle suspensions were then 132
centrifuged at 10,000 g for 20 min with ultrafiltration centrifuge tubes 133
86 cashew gum for encapsulation of Lippia sidoides essential oil via and a molecular weight cutoff of 5 kDa. The supernatant was removed 134
87 spray-drying.18 Although some progress has been made, it is still and the sediments were washed with ethanol and then washed three 135
88 urgent to develop facile and fast approaches for loading the times with water by centrifugation (10,000 g, 20 min). The supernatants 136
89 fragile essential oils. were collected for calculations of the encapsulation efficiency (EE) 137
90 The main objective of this work is to develop a facile, rapid and loading capacity (LC) of PO in the SNPs. The sediments were 138
91 approach for fabricating SNPs via an ultrasonic bottom-up lyophilized for 48 h to obtain dry powders for further analyses. 139
92 method employing various chain lengths of short linear glucan Encapsulation efficiency and loading capacity. The PO 140
93 (SLG). The encapsulation and release properties of peppermint content was calculated using an ultraviolet−visible (UV−vis) 141
spectrometer (290 nm) and a standard calibration curve that was 142
94 oil (PO)-loaded SNPs are also investigated.

■
plotted against the different concentrations of PO. The EE and LC of 143
PO in SNPs were calculated using eqs 1 and 2, respectively.20 144
95 MATERIALS AND METHODS
EE (%) = (total content of PO (mg)
96 Materials. Waxy maize starch (approximately 2% amylose and 98%
97 amylopectin) was supplied by Tianjin Tingfung Starch Development − content of PO in supernatant (mg))
98 Co., Ltd. (Tianjin, China). PO was obtained from Spectrum Chemicals
99 & Laboratory Products (Gardena, CA). Pullulanase (E.C.3.2.1.41, 6000 /total content of PO (mg) × 100 (1) 145
100 ASPU/g, 1.15 g/mL) was purchased from Novozymes Investment Co.,
101 Ltd. (Beijing, China). All reagents used were of analytical grade. LC (%) = (total content of PO (mg)
102 Preparation of short linear glucan from starch. Three types of
103 SLGs with different chain lengths were prepared to investigate the − content of PO in supernatant (mg))
104 formation of SNPs using the ultrasonication method. Primary SLG was /total weight of dry PO‐loaded SNPs × 100 (2) 146
105 prepared by debranching waxy maize starch according to the method of
106 Liu et al. with some modifications.19 First, waxy maize starch was Chain length distributions. Chain length distributions of SLG 147
107 dispersed in disodium hydrogen phosphate and citric acid buffer were analyzed using a high-performance size-exclusion chromatography 148
108 solution (pH 4.6) for fully gelatinization and debranched with (HPSEC) system. HPSEC was carried out according to the method 149
109 pullulanase at 58 °C for 8 h without stirring. Then, the obtained linear of Patindol et al., with some modifications.21 The SLG powder was 150
110 starch molecule solution was precipitated using 4× absolute alcohol dispersed in ultrapure water (1‰ w/v) and then autoclaved at 121 °C 151
111 (solution: absolute alcohol, v/v) at room temperature (25 °C), washed for 30 min. An aliquot (100 μL) of solution was filtered through a filter 152
112 three times with distilled water until a neutral pH was achieved, membrane (0.22 μm pore size). The filtrate was used for chain length 153
113 and freeze-dried at −86 °C for 48 h to obtain primary SLG powder. distributions analysis. Pullulan standards (Mw 342, 1,320, 6,200, 10,600, 154
114 To further fractionate the SLG into two components, absolute ethanol 21,700) were used as references for the determination of the SLG 155
115 (solution: ethanol = 1:3, v/v) was added to fully cooked SLG solutions powder’s chain length. 156
116 at ambient temperature. The supernatant and precipitation were freeze- Transmission electron microscopy (TEM). The morphology 157
117 dried to obtain short SLG (S-SLG) and long SLG (L-SLG), respectively. and size of the SNPs and PO-loaded SNPs were analyzed with a 158
118 Preparation of starch nanoparticles. SNPs were fabricated using Hitachi 7700 transmission electron microscope (Tokyo, Japan) at an 159
119 the ultrasonication method as illustrated in Scheme 1. The primary SLG, acceleration voltage of 80 kV. A droplet (about 10 μL) of SNP or 160

Scheme 1. Schematic Diagram of the Fabrication of Starch Nanoparticles (SNPs) and Peppermint Oil (PO)-Loaded SNPs via an
Ultrasonic Bottom-up Method Employing Various Chain Lengths of Short Linear Glucan (SLG)

B DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

Figure 1. Chain length distributions of primary short linear glucan (SLG) (A), short SLG (S-SLG) (B), and long SLG (L-SLG) (C). SC: standard curve.
DP: degree of polymerization. F1 and F2 represent small and large molecular weight fractions, respectively.

161 PO-loaded SNP suspension was diluted (5:1000) with ultrapure and rate were 4−40° (2θ) and 1.0°/min, respectively. The relative 185
162 water and drop-cast onto a carbon-coated copper grid (400 meshes) crystallinity (RC) of each sample was quantitatively calculated following 186
163 and lyophilized for more than 6 h to obtain dry samples for further Kim’s method, as follows: RC = Ac/(Aa + Ac), where Ac is the crystal- 187
164 observation. line area and Aa is the amorphous area.23 188
165 Dynamic light scattering (DLS). The particle size distributions of Fourier transform infrared (FTIR) spectroscopy. The SNPs and 189
166 SNPs and PO-loaded SNPs were determined using the dynamic light PO-loaded SNPs were mixed with potassium bromide (KBr) powder at 190
167 scattering (DLS) technique with a Zetasizer Nano ZS90 (Malvern, UK). a ratio of 1:100 (sample: KBr, w/w). These admixtures were ground into 191
168 The intensity of light scattered was monitored at 90° angle. The SNP or fine powders and then compressed into thin disk-shaped pellets. 192
169 PO-loaded SNP suspensions were diluted to a concentration of approxi- The pellets were analyzed using a Fourier transform infrared (FTIR) 193
170 mately 1 mg/mL with ultrapure water to avoid multiple scattering spectrometer (Tensor 27, Bruker, Germany) with a mercury cadmium 194

171 effects, and placed into the measurement chamber. Then, they were telluride detector. The FTIR spectra were obtained over the wave- 195

172 equilibrated at 25 ± 1 °C prior to analysis. number range of 400 to 4000 cm−1 at a resolution of 2 cm−1, and the 196
total number of scans was 32. 197
173 Differential scanning calorimetry (DSC). The thermal prop-
The release profile of peppermint oil. The release profile of 198
174 erties of SNPs and PO-loaded SNPs were measured using a differen-
PO-loaded SNPs in a hot water bath was determined according to the 199
175 tial scanning calorimeter (DSC 1, Mettler-Toledo International Inc., method of Dong et al.24 PO-loaded SNPs (10 mg) after lyophilized for 200
176 Switzerland). Three milligram samples (dry basis) with excess water 48 h were directly dispersed in 50 mL of distilled water. The suspensions 201
177 (1:2) were sealed in an aluminum pan. DSC was performed from were divided into five portions and then put in an 80 °C water bath at a 202
178 25 to 125 °C at a heating rate of 10 °C/min.22 The onset (To), peak stirring speed of 150 rpm. Portions were taken out at 30, 60, 90, 120, and 203
179 (Tp), and conclusion temperatures (Tc), and enthalpy change of 150 min and filtered with a filter membrane (Mw = 3.5 kDa) with 204
180 gelatinization (ΔH) of the samples were recorded. The ΔH values were distilled water. The obtained residue was distilled using a Clevenger- 205
181 calculated using the dry weight. type apparatus. Cumulative release (%) of the PO-loaded SNPs in the 206
182 X-ray diffraction (XRD). The crystalline structure of SNPs and 80 °C water bath was determined according to the following formula: 207
183 PO-loaded SNPs were determined by an X-ray diffractometer
184 (D8-ADVANCE, Bruker AXS Model, Germany). The scanning range Cumulative release (%) = (1 − V2/ V1) × 100 (3) 208

C DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

Figure 2. Transmission electron microscopy (TEM) images of starch nanoparticles (SNPs) prepared by primary short linear glucan (SLG) at
concentrations of 1% (w/v) (A), 5% (w/v) (B), and 10% (w/v) (C). Particle size distributions of SNPs were determined by dynamic light scattering
(DLS) (D).

209 where V1 is the initial content of PO and V2 is the content of PO result, S-SLG was retained in the supernatant due to its higher 233
210 obtained from filter residue. solubility, and L-SLG was precipitated due to its lower solubility 234
211 Statistical analysis. All experiments were conducted in triplicate. in the aqueous ethanol solution. Through a series of experiments, 235
212 The experimental data were subjected to statistical analysis with
213 SPSS 17.0 software (SPSS Inc., Chicago, USA). Duncan’s multiple range
primary SLG was fractionated into S-SLG and L-SLG with the 236

214 tests were also applied to determine the difference of means from ethanol to water ratio of 3:1 (v/v). 237
215 the analysis of variance (ANOVA), using a significance test level of 5% Chain length distributions of primary SLG, S-SLG, and L-SLG 238
216 (p < 0.05). samples are shown in Figure 1, and the composition percentages 239

217

218
■ RESULTS AND DISCUSSION
Chain length distributions of short linear glucan. The
are calculated in Table S1. The major population of SLG, with a
low degree of polymerization (DP), was labeled F1; the rest,
which had a high DP, was labeled F2. Compared with S-SLG, the
240
241
242

219 alcohol precipitation method is commonly used to separate contents of minor components of F2 were somewhat higher in 243

220 polysaccharides from their aqueous solution due to its simplicity, primary SLG and L-SLG, which were considered to represent 244
221 rapidity, easy scalability, and cost effectiveness. The precipitation amylopectin that was not fully debranched. The peak DP value of 245
222 levels of polysaccharides at different concentrations of ethanol primary SLG was 13.5, with a shoulder peak at DP 30, and 246
223 present different characteristics, including polymer recovery, the relative content of F1 was 97.4 ± 0.71% (Table S1). After 247
224 chemical composition, molecular weight, and morphological fractionation with 3× absolute alcohol (solution: absolute 248
225 appearance. In Liu et al.’s study, water-soluble polysaccharide alcohol = 1:3, v/v), the S-SLG obtained from supernatant 249
226 was isolated and purified from Achatina f ulica by papain enzy- contained only one main peak (DP 9.5), which made up 78.1 ± 250
227 molysis and alcohol precipitation.25 In Wang et al.’s experiment, 0.58% (Table S1). In contrast, the L-SLG obtained from the 251
228 solvent extraction (water and alcohol) and organic solvent precipitate had a main peak (DP 15.1) with a shoulder peak 252
229 fractional extraction were used to extract crude polysaccharides (DP 30). Hanashiro et al. categorized amylopectin branch chains 253
230 from the dried pumpkin pulp.26 into several types with their corresponding DP values, as follows: 254
231 In the present study, we added ethanol to the primary SLG A chain (DP 6−12), B1 chain (DP 13−24), B2 chain (DP 25−36), 255
232 aqueous solution to obtain various chain lengths of SLG; as a and B3+ chain (DP 37−65).27 In our work, primary SLG was a 256

D DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

Figure 3. Transmission electron microscopy (TEM) images of starch nanoparticles (SNPs) prepared at ultrasound irradiation times of 5 min (A, E, and
I), 8 min (B, F, and J), and 10 min (C, G, and K). Particle size distributions of SNPs were measured using dynamic light scattering (DLS) (D, H, and I).

257 mixture of debranched waxy maize starch with different DP values, nonuniform in size and distribution. When the SLG content was 269
258 mainly including A chains and B chains (B1 and B2). increased up to 5%, the obtained SNPs had a uniform, compact, 270
259 Effects of short linear glucan concentration. To smooth spherical shape, with diameters of 150−200 nm. The size 271
260 investigate the effect of SLG concentration on SNP formation, distribution of SNPs determined by DLS showed only one peak, 272
261 we used primary SLG for self-assembly under ultrasonic treat- which was consistent with the TEM result. A further increment in 273
262 ment. The morphology and mean size of SNPs prepared at the SLG concentration to 10% resulted in the formation of 274
263 different SLG concentrations were determined by transmission large and aggregated particles (200−300 nm). Furthermore, 275
264 electron microscopy (TEM) and DLS (Figure 2). When the the DLS result showed two separated peaks, with the bigger 276
265 concentration was 1%, SLG self-assembled to form small, one belonging to the micron level. Therefore, 5% SLG solution 277
266 irregular, spherical nanoparticles with a size ranging from 10 to was the optimum concentration to produce uniform SNPs 278
267 150 nm, and no agglomeration occurred. Moreover, the result of for subsequent studies. Similarly, Hebeish et al. found that 279
268 DLS showed two separated peaks, indicating that SNPs were increasing the concentration of native maize starch had a major 280

E DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

281 adverse effect on the formation of monodispersity of the nano- Table 1. Encapsulation Efficiency (EE) and Loading Capacity
282 particles.28 (LC) of Peppermint Oil (PO)-Loaded Starch Nanoparticles
283 Effect of ultrasonic irradiation time. Various ultrasonic (SNPs)a
284 irradiation times were employed to determine their effect on the
SNPs EE (%) LC (%) Yield (%)
285 morphology and particle size of SNPs prepared by different
286 SLGs. Figures 3A−C, E−G, and I−K show the TEM images of SLG 82.9 ± 0.54 b 25.1 ± 0.14 b 86.2 ± 0.24 b
287 primary SLG, S-SLG, and L-SLG nanoparticles, respectively, S-SLG 74.5 ± 0.35 c 21.3 ± 0.17 c 81.8 ± 0.32 c
288 prepared at irradiation times of 5, 8, and 10 min. The mor- L-SLG 87.7 ± 0.38 a 25.5 ± 0.21 a 93.2 ± 0.36 a
289 phology and size of primary SLG and L-SLG nanoparticles
a
Values presented as mean ± SD indicate the replicates of three
290 evolved with the same change tendency as a function of time. experiments. Values with different letters (a, b, c, and d) are signifi-
291 With increasing irradiation time, the diameter of the aggregates cantly different (p < 0.05). SLG, S-SLG, and L-SLG: peppermint oil
292 increased correspondingly. After ultrasonic processing for 5 min, (PO)-loaded primary short linear glucan (SLG) nanoparticles, short
SLG nanoparticles, and long SLG nanoparticles, respectively.
293 the sizes of primary SLG (Figure 3A) and L-SLG (Figure 3I)
294 nanoparticles were 100 and 150 nm, respectively. As self-
295 assembling continued (Figure 3B and J), monodisperse method.31 de Oliveira et al. reported that essential oil- 344
296 nanoparticles with regular shapes (200 nm) were formed. encapsulated alginate/cashew gum nanoparticles were success- 345
297 It was noted that the SNP aggregates were formed after fully prepared via spray-drying, and the encapsulated oil levels 346
298 ultrasonication for 10 min (Figure 3C and K). As for S-SLG, only varied from 1.9% to 4.4%, with an EE of up to 55%.18 The ultra- 347
299 small portions of nanoparticles were formed after treatment for sonic bottom-up approach seems to be the best among those 348
300 5 min. Nanoparticles of irregular shape were formed following used to prepare nanocarriers in terms of the EE and LC of 349
301 sonication for 8 min. Significantly, S-SLG took a somewhat long essential oil loading. 350
302 period (10 min) to form compact nanoparticles with a spherical Characteristics of starch nanoparticles and pepper- 351
303 morphology; the size of the SNPs was determined to be 150 nm. mint oil-loaded starch nanoparticles. The morphology and 352
304 Referring to the DLS measurement, the particles size was particle size of PO-loaded SNPs are shown in Figure 4. 353
305 rather larger than that revealed by TEM observation. For the After encapsulation, the nanoparticles remained spherical, with 354
306 primary SLG sample, the particle size of formed SNPs increased a size of around 200 nm for all three samples (Figure 4A, C, 355
307 from 100 to 2,000 nm (Figure 3D) as irradiation time increased and E). PO incorporation led to the formation of particles with 356
308 from 5 to 10 min, which could have occurred because more slightly larger diameters from the DLS results (Figure 4B, D, 357
309 energy provided by ultrasonication made the SNPs grow and and F). Bilenler et al. also reported that the dimensions of 358
310 then aggregate. The DLS results also showed that S-SLG and essential oil-loaded zein particles are greater than that of blank 359
311 L-SLG nanoparticles exhibited increased size with increasing zein particles.32 360
312 irradiation time. These results suggested that the shapes and sizes The thermal properties. The thermal properties of SNPs 361
313 of SNPs produced via ultrasonication were highly influenced obtained using the ultrasonic process were determined by DSC. 362
314 by irradiation time. Abbas et al. also reported an increase in the The SNPs prepared by primary SLG, S-SLG, and L-SLG 363
315 mean size of sodium chloride particles by applying sonication all showed one endotherm, with temperature ranges of 64.0− 364
316 within 20 min.29 94.3 °C, 50.3−81.1 °C, and 75.1−97.6 °C, respectively, as 365
317 The above results suggested that SLG could rapidly form depicted in Figure 5A. However, primary SLG did not show an 366
318 nanoscale starch particles with a size of around 200 nm via the endothermic peak, reflecting its mainly amorphous structure. 367
319 ultrasonic bottom-up method. To explore the application of Furthermore, the melting temperature of SNPs was positively 368
320 these newly developed SNPs as a nanocarrier, PO was used as a correlated with the DP of SLG. This behavior was probably due 369
321 model substance to be loaded into SNPs. The morphological to the more perfect crystal structure formed by SLG with a higher 370
322 characteristics, crystal structure, EE, LC, and release profile of the DP value, which requires a higher temperature to dissociate 371
323 resulting SNPs were investigated. the crystallization. It has been reported that a minimum chain 372
324 Encapsulation efficiency and loading capacity. The length of DP 10 is required for double helix formation in a pure 373
325 effects of various SLG chain lengths on the EE and LC of PO in oligosaccharide solution.33 374
326 SNPs were measured. As shown in Table 1, the EE of the three The thermal properties of PO-loaded SNPs are shown in 375
327 PO-loaded SNPs dropped from 87.7% to 74.5% with decreasing Figure 5B. The melting temperature ranges of primary SLG and 376
328 chain lengths from DP 15.1 to DP 9.5. The LC of the primary L-SLG with PO were about 79.7−106.9 °C and 83.6−110.0 °C, 377
329 SLG (DP 13.5) and L-SLG (DP 15.1) nanoparticles was higher respectively. The addition of PO resulted in a further increase of 378
330 than that of the S-SLG (DP 9.5) nanoparticles. The yield of the the Tp in SNPs. The shift to the higher temperature and wider 379
331 PO-loaded SNPs increased from approximately 81.8% to 93.2% range for melting indicated that a more crystalline structure of 380
332 with the increase of the SLG chain lengths. The results suggested the V-type complexes was formed by primary SLG or L-SLG with 381
333 that the EE and LC values of the PO-loaded SNPs were enhanced PO. Similar results have been reported by Jane, who stated 382
334 as the SLG chain lengths increased. With a high EE of that the semicrystalline amylose inclusion complexes melt at 383
335 74.5−87.7% and high LC of 21.3−25.5%, the prepared SNPs 100−125 °C.34 The same trend was noted by Maphalla et al. and 384
336 could be a potential carrier for essential oils. In a previous work, Ai et al., who showed that the addition of lipid to starch increased 385
337 the Lippia sidoides essential oil was encapsulated by a chitosan the melting temperature.35 However, the SNPs fabricated by 386
338 and “angico” gum matrix, with LC between 3% and 7% and EE in S-SLG and PO had two endothermic peaks, with temperature 387
339 the range 16−77%.30 ranges of about 48.0 °C−79.8 °C and 91.3−98.3 °C. This may be 388
340 In general, the PO-loaded SNPs fabricated using the ultrasonic attributed to the formation of a double-helix structure by SLG 389
341 bottom-up method generated higher LC, EE, and encapsulation self-assembly and a single-helix structure between SLG and PO 390
342 yields compared to the polycaprolactone-coated nanocapsules in the first and second peaks, respectively. Recently, Le-Bail 391
343 incorporated with the essential oil by the emulsion-diffusion reported that the thermogram obtained from amylose complexes 392

F DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

Figure 4. Transmission electron microscopy (TEM) images and dynamic light scattering (DLS) analyses of peppermint oil (PO)-loaded primary short
linear glucan (SLG) (A, B), short SLG (S-SLG) (C, D), and long SLG (L-SLG) nanoparticles (NPs) (E, F), respectively.

393 with linoleic acid has a complex shape with two endotherms, the the X-ray diffraction (XRD) patterns of the three SNP samples. 399
394 first at 87 °C and the second at 106 °C.36 The XRD results showed that the SNPs were characteristic of the 400
395 X-ray diffraction analysis (XRD). The RCs of SNPs formed B-type, with strong peaks at 2θ of 17°, 22°, and a weak peak 401
396 by primary SLG, S-SLG, and L-SLG were also measured. The RC at 24° (Figure 6A). This was consistent with a previous report 402
397 value of primary SLG was about 6%, indicating that it had an stating that recrystallized nanoscale starch particle samples prepared 403
398 almost amorphous structure. There was no difference between from proso millet starch displayed a typical B-type crystalline 404

G DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

Figure 5. Differential scanning calorimetry (DSC) thermal profiles of starch nanoparticles (SNPs) (A) and peppermint oil (PO)-loaded SNPs (B).

Figure 6. X-ray patterns of starch nanoparticles (SNPs) (A) and peppermint oil (PO)-loaded SNPs (B). RC: relative crystallinity.

405 structure with the main diffraction peaks at 2θ = 5.6°, 17.1°, 22.5°, formation of SNPs, further studies were carried out using 427
406 and 24.3°.37 The RCs of SNPs increased remarkably (from 23.5 ± FTIR. The spectra of the SNPs showed a characteristic peak 428
407 0.9 to 31.6 ± 1.5%) with the increasing SLG chain lengths. around 3400 cm−1 that may be assigned to inter- and intra- 429
408 In contrast to the B-type diffraction pattern of bare SNPs, molecular hydrogen-bonded hydroxyl groups (Figure 7A). 430
409 the PO-loaded SNPs exhibited a distinct V-type single-helix A small peak at 2930 cm−1 was attributed to the C−H stretching 431
410 crystalline structure (Figure 6B). The characteristic diffraction vibrations. The peak at 1640 cm−1 was a feature of tightly bound 432
411 peaks of PO-loaded L-SLG nanoparticles were at 2θ = 7.5°, water present in the nanoparticles. Similarly, the characteristic 433
412 13.1°, and 20.3°. Similarly, the main reflections of PO-loaded bands of FTIR spectra of primary SLG were identical to those of 434
413 SNPs obtained by primary SLG at 2θ were about 7.5°, 12.4°, the SNPs. However, the band of SNPs decreased in intensity 435
414 and 19.5°. However, the PO-loaded S-SLG nanoparticles had when compared with primary SLG due to inter- and intra- 436
415 two weak peaks at 2θ of about 16.0° and 22.1°. The RCs of molecularly bound hydroxyl groups. These results were 437
416 PO-loaded S-SLG, primary SLG, and L-SLG nanoparticles were comparable to the findings of a recent report, which showed 438
417 24.3 ± 1.7%, 31.4 ± 1.4%, and 36.2 ± 2.4%, respectively, which that the OH stretching band at 3435.7 cm−1 in SNPs decreased in 439
418 were higher (p < 0.05) than the corresponding RCs of bare SNPs. intensity compared to that in the native maize starch.28 440
419 These results proved that SLG had the capability to form a FTIR spectroscopy was further applied to study the inter- 441
420 V-type single-helical structure with essential oils under ultrasonic actions between PO and SNPs in PO-loaded SNPs. Compared to 442
421 treatments. Le-Bail et al. demonstrated that V-amylose forms bare SNPs, the characteristic peak of PO-loaded SNPs shifted 443
422 helices with hydrophobic helical cavities; they suggested that toward a shorter frequency (around 3937 cm−1), which indicated 444
423 these helices could entrap the guest molecules to various that there were stronger intermolecular hydrogen bonds between 445
424 extents.36 PO and SLG, as observed by Qiu et al. in a similar study. These 446
425 Fourier transform infrared (FTIR) spectroscopic study. authors reported that characteristic bands at 3000−3700 cm−1 in 447
426 To investigate the interactions that occurred during the the SNPs-menthone spectrum shift to a shorter wavelength, 448

H DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

Figure 7. Fourier transform infrared (FTIR) spectra of starch nanoparticles (SNPs) (A) and peppermint oil (PO)-loaded SNPs (B).

Figure 8. Release profile (A) of peppermint oil (PO) from primary short linear glucan (SLG), short SLG (S-SLG), and long SLG (L-SLG) nanoparticles
(NPs) in hot water at 80 °C and fitted by the pseudo-first-order kinetic model (B).

449 indicating stronger hydrogen bonding between the hydroxyls of release amount. Approximately 33% of the PO was released 467
450 SLG and menthone in the menthone-loaded SNPs.15 The PO from the S-SLG nanoparticles after incubation for 150 min. 468
451 characteristic bands, particularly those of aromatic compounds In contrast, the primary SLG and L-SLG nanoparticles released 469
452 (at 2960, 1440, 1580, and 1600 cm−1), exhibited low intensity or about 28% and 27% of the PO, respectively, after 150 min of 470
453 disappeared. The changes in the FTIR spectra on PO-loaded incubation. 471
454 SNPs can be explained by the complex formation between SLG To understand the PO release process, the most common 472
455 and PO. pseudo-first-order kinetics model was used to analyze PO release 473
456 Release profile of peppermint oil−loaded starch in solution. The equation was expressed as follows: 474
457 particles at high temperature. The release behavior of Qt = Qe(1 − exp(−kt )) (4) 475
458 PO-loaded SNPs under heating conditions was further evaluated.
−1
459 Compared to pure PO (data not shown), the cumulative release where k is the rate constant of pseudo-first-order release (min ), 476
460 amount of PO in SNPs markedly decreased (Figure 8A). It was Qe is the maximal release amount of PO at an infinite time, and 477
461 observed that PO released from the three PO-loaded SNPs Qt is the cumulative release amount of PO at time t. 478
462 reached a level of maximal release (plateau) around 120 min. The fitting results of the release profiles and kinetic model 479
463 The decrease in cumulative release of PO can probably be parameters of PO from the SNPs are shown in Figure 8B 480
464 attributed to the compact SNPs formation between SLG and and Table S3, respectively. The best correlation coefficient 481
465 PO. Compared to the other two types of PO-loaded SNPs, the (R2 > 0.99) was obtained for the kinetic model. Here, PO-loaded 482
466 PO-loaded S-SLG nanoparticles showed a slightly higher S-SLG nanoparticles exhibited a high maximal release amount. 483

I DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

484 In contrast, low release of SNPs and L-SLG nanoparticles was (6) Qiu, C.; Yang, J.; Ge, S.; Chang, R.; Xiong, L.; Sun, Q. Preparation 543
485 observed. In the whole release profile, it could be observed that and characterization of size-controlled starch nanoparticles based on 544
486 PO-loaded SNPs displayed a noticeably low release property, short linear chains from debranched waxy corn starch. LWT - Food 545
487 indicating that they are stable against high temperature. This Science and Technology 2016, 74, 303−310. 546
488 result suggested that SNPs may be effective carriers for essential (7) Yariv, I.; Lipovsky, A.; Gedanken, A.; Lubart, R.; Fixler, D. 547
Enhanced pharmacological activity of vitamin B(1)(2) and penicillin as 548
489 oil or other hydrophobic substances.
nanoparticles. Int. J. Nanomed. 2015, 10, 3593−601. 549
490 In conclusion, the current study presented the formation of (8) Sun, Q.; Fan, H.; Xiong, L. Preparation and characterization of 550
491 SNPs via an ultrasonic bottom-up approach using different SLG starch nanoparticles through ultrasonic-assisted oxidation methods. 551
492 chain lengths. The new method was also used to encapsulate PO Carbohydr. Polym. 2014, 106, 359−364. 552
493 into SNPs, which showed a rapid process at a minute time (9) Bel Haaj, S.; Magnin, A.; Petrier, C.; Boufi, S. Starch nanoparticles 553
494 scale (5 or 8 min), high LC of 25.5%, and high EE of 87.7%. formation via high power ultrasonication. Carbohydr. Polym. 2013, 92 554
495 The as-prepared nanoparticles and PO-loaded SNPs exhibited (2), 1625−1632. 555
496 spherical shapes with smooth surfaces. Particle sizes were in the (10) Li, Z.; Jiang, H.; Xu, C.; Gu, L. A review: Using nanoparticles to 556
497 range 150−220 nm, with no aggregates. Compared with SNPs, enhance absorption and bioavailability of phenolic phytochemicals. Food 557
498 PO-loaded SNPs exhibited increased crystallinity, as determined Hydrocolloids 2015, 43, 153−164. 558
499 via XRD analysis. The thermal analysis and X-ray studies (11) Thiruvengadathan, R.; Korampally, V.; Ghosh, A.; Chanda, N.; 559
500 provided evidence that the PO-loaded SNPs formed the V-type Gangopadhyay, K.; Gangopadhyay, S. Nanomaterial processing using 560
501 of crystallinity. Encapsulation of POs in the SNPs greatly slowed self-assembly-bottom-up chemical and biological approaches. Rep. Prog. 561

502 their release in hot water. The present approach has the Phys. 2013, 76 (6), 066501. 562
(12) Rondeau-Mouro, C.; Bail, P. L.; Buléon, A. Structural 563
503 advantage of being rapid, presenting a higher yield, and not
investigation of amylose complexes with small ligands: inter- or intra- 564
504 requiring any chemical treatment. The knowledge obtained from helical associations? Int. J. Biol. Macromol. 2004, 34 (5), 251−257. 565
505 this study will be helpful in the design and development of new (13) Meng, S.; Ma, Y.; Sun, D.-W.; Wang, L.; Liu, T. Properties of 566
506 strategies to encapsulate essential oils. Essential oil-loaded SNPs starch-palmitic acid complexes prepared by high pressure homoge- 567
507 can be used for applications in medicine, functional foods, and nization. J. Cereal Sci. 2014, 59 (1), 25−32. 568
the cosmetics field.

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508 (14) Ocloo, F. C.; Minnaar, A.; Emmambux, N. M. Effects of stearic 569
acid and gamma irradiation, alone and in combination, on pasting 570
509 ASSOCIATED CONTENT properties of high amylose maize starch. Food Chem. 2016, 190, 12−9. 571
510 *
S Supporting Information (15) Qiu, C.; Chang, R.; Yang, J.; Ge, S.; Xiong, L.; Zhao, M.; Li, M.; 572
511 The Supporting Information is available free of charge on the Sun, Q. Preparation and characterization of essential oil-loaded starch 573
512 ACS Publications website at DOI: 10.1021/acs.jafc.7b02938. nanoparticles formed by short glucan chains. Food Chem. 2017, 221, 574
1426−1433. 575
513 Data of chain length distributions, data of DSC, and kinetic (16) Liang, R.; Xu, S.; Shoemaker, C. F.; Li, Y.; Zhong, F.; Huang, Q. 576
514 model parameters (PDF) Physical and antimicrobial properties of peppermint oil nanoemulsions. 577

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J. Agric. Food Chem. 2012, 60 (30), 7548−7555. 578
515 AUTHOR INFORMATION (17) Lv, Y.; Yang, F.; Li, X.; Zhang, X.; Abbas, S. Formation of heat- 579
resistant nanocapsules of jasmine essential oil via gelatin/gum arabic 580
516 Corresponding Author
based complex coacervation. Food Hydrocolloids 2014, 35, 305−314. 581
517 *Tel: +86-0532-88030448. Fax: +86-0532-88030449. E-mail: (18) de Oliveira, E. F.; Paula, H. C.; de Paula, R. C. Alginate/cashew 582
518 phdsun@163.com (Qingjie Sun). gum nanoparticles for essential oil encapsulation. Colloids Surf., B 2014, 583
519 ORCID 113, 146−151. 584
520 Qingjie Sun: 0000-0002-7371-1052 (19) Liu, C.; Qin, Y.; Li, X.; Sun, Q.; Xiong, L.; Liu, Z. Preparation and 585
characterization of starch nanoparticles via self-assembly at moderate 586
521 Notes
temperature. Int. J. Biol. Macromol. 2016, 84, 354−360. 587
The authors declare no competing financial interest.

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522
(20) Liu, C.; Ge, S.; Yang, J.; Xu, Y.; Zhao, M.; Xiong, L.; Sun, Q. 588
Adsorption mechanism of polyphenols onto starch nanoparticles and 589
523 ACKNOWLEDGMENTS enhanced antioxidant activity under adverse conditions. J. Funct. Foods 590
524 The study was supported by the National Natural Science 2016, 26, 632−644. 591
Foundation, China (Grant No. 31671814). (21) Patindol, J. A.; Gonzalez, B. C.; Wang, Y.-J.; McClung, A. M.

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525 592
Starch fine structure and physicochemical properties of specialty rice for 593
526 REFERENCES canning. J. Cereal Sci. 2007, 45 (2), 209−218. 594
527 (1) Bahrani, S. A.; Loisel, C.; Rezzoug, S. A.; Cohendoz, S.; Buleon, A.; (22) Sun, Q.; Li, G.; Dai, L.; Ji, N.; Xiong, L. Green preparation and 595
528 Maache-Rezzoug, Z. Physicochemical and crystalline properties of characterisation of waxy maize starch nanoparticles through enzymolysis 596
529 standard maize starch hydrothermally treated by direct steaming. and recrystallisation. Food Chem. 2014, 162 (11), 223−228. 597
530 Carbohydr. Polym. 2017, 157, 380−390. (23) Kim, H. Y.; Park, D. J.; Kim, J. Y.; Lim, S. T. Preparation of 598
531 (2) Le Corre, D.; Angellier-Coussy, H. Preparation and application of crystalline starch nanoparticles using cold acid hydrolysis and 599
532 starch nanoparticles for nanocomposites: A review. React. Funct. Polym. ultrasonication. Carbohydr. Polym. 2013, 98 (1), 295−301. 600
533 2014, 85, 97−120. (24) Dong, Z.; Ma, Y.; Hayat, K.; Jia, C.; Xia, S.; Zhang, X. Morphology 601
534 (3) Liu, C.; Jiang, S.; Zhang, S.; Xi, T.; Sun, Q.; Xiong, L. and release profile of microcapsules encapsulating peppermint oil by 602
535 Characterization of edible corn starch nanocomposite films: The effect complex coacervation. J. Food Eng. 2011, 104 (3), 455−460. 603
536 of self-assembled starch nanoparticles. Starch - Stärke 2016, 68 (3−4), (25) Liu, J.; Shang, F.; Yang, Z.; Wu, M.; Zhao, J. Structural analysis of a 604
537 239−248. homogeneous polysaccharide from Achatina fulica. Int. J. Biol. Macromol. 605
538 (4) Kim, H. Y.; Park, S. S.; Lim, S. T. Preparation, characterization and 2017, 98, 786−792. 606
539 utilization of starch nanoparticles. Colloids Surf., B 2015, 126, 607−20. (26) Wang, S.; Lu, A.; Zhang, L.; Shen, M.; Xu, T.; Zhan, W.; Jin, H.; 607
540 (5) Sun, Q.; Li, G.; Dai, L.; Ji, N.; Xiong, L. Green preparation and Zhang, Y.; Wang, W. Extraction and purification of pumpkin 608
541 characterisation of waxy maize starch nanoparticles through enzymolysis polysaccharides and their hypoglycemic effect. Int. J. Biol. Macromol. 609
542 and recrystallisation. Food Chem. 2014, 162, 223−228. 2017, 98, 182−187. 610

J DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX
 Journal of Agricultural and Food Chemistry Article

611 (27) Hanashiro, I.; Abe, J. I.; Hizukuri, S. A periodic distribution of the
612 chain length of amylopectin as revealed by high-performance anion-
613 exchange chromatography. Carbohydr. Res. 1996, 283 (10), 151−159.
614 (28) Hebeish, A.; El-Rafie, M. H.; El-Sheikh, M. A.; El-Naggar, M. E.
615 Ultra-Fine Characteristics of Starch Nanoparticles Prepared Using
616 Native Starch With and Without Surfactant. J. Inorg. Organomet. Polym.
617 Mater. 2014, 24 (3), 515−524.
618 (29) Abbas, A.; Srour, M.; Tang, P.; Chiou, H.; Chan, H.-K.;
619 Romagnoli, J. A. Sonocrystallisation of sodium chloride particles for
620 inhalation. Chem. Eng. Sci. 2007, 62 (9), 2445−2453.
621 (30) Paula, H. C. B.; Sombra, F. M.; Cavalcante, R. d. F.; Abreu, F. O.
622 M. S.; de Paula, R. C. M. Preparation and characterization of chitosan/
623 cashew gum beads loaded with Lippia sidoides essential oil. Mater. Sci.
624 Eng., C 2011, 31 (2), 173−178.
625 (31) Pinto, N. d. O. F.; Rodrigues, T. H. S.; Pereira, R. d. C. A.; Silva, L.
626 M. A. e.; Cáceres, C. A.; Azeredo, H. M. C. d.; Muniz, C. R.; Brito, E. S.
627 d.; Canuto, K. M. Production and physico-chemical characterization of
628 nanocapsules of the essential oil from Lippia sidoides Cham. Ind. Crops
629 Prod. 2016, 86, 279−288.
630 (32) Bilenler, T.; Gokbulut, I.; Sislioglu, K.; Karabulut, I. Antioxidant
631 and antimicrobial properties of thyme essential oil encapsulated in zein
632 particles. Flavour Fragrance J. 2015, 30 (5), 392−398.
633 (33) Abell, A. D.; Ratcliffe, M. J.; Gerrard, J. Ascorbic acid-based
634 inhibitors of α-amylases. Bioorg. Med. Chem. Lett. 1998, 8 (13), 1703−
635 1706.
636 (34) Jane, J. L. Structural Features of Starch Granules II[M]//. Starch.
637 Elsevier Inc. 2009, 193−236.
638 (35) (a) Maphalla, T. G.; Emmambux, M. N. Functionality of maize,
639 wheat, teff and cassava starches with stearic acid and xanthan gum.
640 Carbohydr. Polym. 2016, 136, 970−978. (b) Ai, Y.; Hasjim, J.; Jane, J. L.
641 Effects of lipids on enzymatic hydrolysis and physical properties of
642 starch. Carbohydr. Polym. 2013, 92 (1), 120−127.
643 (36) Le-Bail, P.; Houinsou-Houssou, B.; Kosta, M.; Pontoire, B.; Gore,
644 E.; Le-Bail, A. Molecular encapsulation of linoleic and linolenic acids by
645 amylose using hydrothermal and high-pressure treatments. Food Res. Int.
646 2015, 67, 223−229.
647 (37) Sun, Q.; Gong, M.; Li, Y.; Xiong, L. Effect of retrogradation time
648 on preparation and characterization of proso millet starch nanoparticles.
649 Carbohydr. Polym. 2014, 111, 133−138.

K DOI: 10.1021/acs.jafc.7b02938
J. Agric. Food Chem. XXXX, XXX, XXX−XXX

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