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Storage stability of encapsulated ascorbyl palmitate in normal and high amylose maize starches during pasting and spray dryin
Carbohydrate Polymers 216 (2019) 217–223
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Storage stability of encapsulated ascorbyl palmitate in normal and high amylose maize starches during pasting and spray dryin O.P. Bamidele, M.N. Emmambux
T
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Department of Consumer and Food Sciences, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
A R T I C LE I N FO
A B S T R A C T
Keywords: Encapsulation Spray drying High amylose maize starch Ascorbyl palmitate
This study determines storage stability and release of encapsulated ascorbyl palmitate in normal and high amylose maize starch by pasting and spray drying. The amount of ascorbyl palmitate released was analysed in the stored samples (dark cupboard, and under UV light at a temperature of 40 °C for 12 weeks) and their antioxidant activity determined. Storage of encapsulated ascorbyl palmitate at 40 °C under both dark and UV light conditions did not affect the amount release and the ability to scavenge the free radical (ABTS+). However, the antioxidant activity of free ascorbyl palmitate exponentially decreased at 40 °C under UV light condition. The analysed residues after α-amylase digestion of encapsulated ascorbyl palmitate showed some endothermic peaks, suggesting that amylose-lipids complexes formed were resistant to α-amylase digestion. Encapsulation of ascorbyl palmitate in maize starch may improve its storage stability under light (UV) conditions.
1. Introduction Storage stability of functional foods is considered a critical requirement before such food products are sold in the market. Storage stability is necessary to ensure the efficacy of the bioactive compounds in functional foods under different storage conditions and during the shelf life (Singh & Bakshi, 2000). The potency of ascorbyl palmitate has been found to reduce during storage conditions such as under light and in the presence of oxygen (Špiclin, Gašperlin, & Kmetec, 2001), also in stomach conditions (Yuan & Chen, 1998). Encapsulation of bioactive compounds have been found to improve their stability (Saénz, Tapia, Chávez, & Robert, 2009). Encapsulation of bioactive compounds are carried out with different methods. These methods can be categorised as (i) physical method for example Spray drying, (ii) physico-chemical method for example complex coacervation, hydrophobic interaction, cooling of emulsion, solvent removal, ionic gelation, extrusion cooking, electrospinning, and acid precipitation, (iii) chemical method for example in situ polymerization, interfacial polycondensation and interfacial cross-linking (Munin & Edwards-Lévy, 2011). Encapsulation by polymeric carriers is an approach widely used to preserve bioactive compounds. In addition to the preservation effects, it may control the release or delivery of the encapsulated or entrapped ingredients thereby improving their bioavailability in humans (Dima, Dima, & Iordăchescu, 2015). Encapsulation of an insoluble substance
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may improve its dispersion rate and storage stability, and this often may result in the bioavailability of the insoluble substance being enhanced (Dima et al., 2015). Encapsulation of bioactive compound such as genistein (Cohen, Orlova, Kovalev, Ungar, & Shimoni, 2008), flavour compounds (Jafari, Assadpoor, He, & Bhandari, 2008), phenolic compounds (Lalush, Bar, Zakaria, Eichler, & Shimoni, 2005) has been achieved with the use of normal and high amylose maize starch and other materials like fish oil. Kong and Ziegler (2014) encapsulated ascorbyl palmitate in amylose and high amylose maize starch by annealing (Heating of starch and amylose in aqueous ethanol at different temperature for 10 min) and use of DMSO (dimethyl sulphur oxide). They reported encapsulation of ascorbyl palmitate in both amylose and starch. Ascorbyl palmitate was also encapsulated in solid lipid nanoparticles (made from Glycery monostearate and paclitaxel (PTX) by Zhou et al. (2017). The encapsulation of ascorbyl palmitate in paclitaxel and solid lipid nanoparticle had a synergistic effect to suppress tumour cell growth murine B16F10 melanoma that had metastasized to the lungs of mice in suppressing tumour growth in murine B16F10-bearing mice and in eliminating cancer cells in the lungs as compared to the single drug alone. In our recent work, we have shown that ascorbyl palmitate was encapsulated in normal maize starch by formation of amylose-ascorbyl palmitate complexes after pasting at 90°C for 2 h (Bamidele, Duodu, & Emmambux, 2017). Ascorbyl palmitate was also encapsulated in both normal and high amylose maize starch during spray drying
Corresponding author. E-mail address: [email protected] (M.N. Emmambux).
https://doi.org/10.1016/j.carbpol.2019.04.022 Received 6 December 2018; Received in revised form 25 March 2019; Accepted 4 April 2019 Available online 09 April 2019 0144-8617/ © 2019 Elsevier Ltd. All rights reserved.
Carbohydrate Polymers 216 (2019) 217–223
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(185 ± 1°C) through the formation of amylose-ascorbyl palmitate complexes and entrapment in a starch matrix (Bamidele, Duodu, & Emmambux, 2019). Dries, Knaepen, Goderis, and Delcour, (2017) also encapsulated ascorbyl palmitate to form V-type granular cold-water swelling starch (GCWSS) using both maize and potato starches. Encapsulation enabled partial release of ascorbyl palmitate when hydrolysed with α-amylase for 180 min and this suggests that some of the encapsulated ascorbyl palmitate may reach the large intestine. Špiclin et al. (2001) reported stability of antioxidant activities of encapsulated ascorbyl palmitate in different micro-emulsion (Capric triglyceride, Mygliol 812 and Labrasol) during storage at 25 °C in a dark container. Best to our knowledge, there is no reported literature on stability during storage for encapsulated ascorbyl palmitate in maize starch that form amylose lipid complexes. Stability of other encapsulated bioactive compounds for example microencapsulated polyphenolic compounds that provide antioxidant properties during storage have been studied. Bakowska-Barczak and Kolodziejczyk (2011) studied the stability of microencapsulated black currant polyphenols during storage for 12 months at 8 °C and 25 °C. They reported that the antioxidant activity of released microencapsulated black currant polyphenol in maltoderin DE11 during 12 months storage at 8 °C and 25 °C in brown bottle was similar to natural black currant polyphenol before encapsulation, but those that were not encapsulated showed reduction in antioxidant activity. This shows that there was no degradation of the bioactive compounds (black currant polyphenol) during storage when compared with non-encapsulated black currant polyphenol that degraded during storage. Similarly, Luca, Cilek, Hasirci, Sahin, and Sumnu, (2014) determined the stability of encapsulated sour cherry phenolic compounds in mixture of maltodextrin and gum Arabic (8% maltodectrin to 2% gum Arabic) during storage at 43% relative humidity for 48 h and used in a food system. They reported a loss of 37% of antioxidant activity of non-encapsulated extracted crude phenolic compounds and 43% loss of antioxidant activities from extracted and purified non-encapsulated phenolic compounds during storage. In comparison, there was 10% loss of the antioxidant activities of extracted phenolic compounds and 15% loss of antioxidant activities of extracted purified phenolic compounds during storage when the phenolic compounds were microencapsulated. The degradation of free ascorbyl palmitate is due to the effects of the oxidative reaction catalyzed by a metal ion or light (Špiclin et al., 2001). Oxidative degradation occurs more in dilute systems, indicating that the initial concentration of the ascorbyl palmitate is an important factor that contributes to the extent of degradation (Carstensen, 2000). The storage stability of encapsulated ascorbyl palmitate through determination of antioxidant activity is required to assess the efficacy of the guest molecule (ascorbyl palmitate). This would also help elucidate the effect of different storage conditions on the shelf life and antioxidant activities of encapsulated ascorbyl palmitate. The hypothesis is that encapsulated ascorbyl palmitate in maize starches (normal and high amylose maize starch) is expected to be stable under light (UV) and dark condition at accelerated temperature of 40 °C because ascorbyl palmitate formed a amylose-ascorbyl palmitate complexes with amylose during pasting (Bamidele et al., 2017) or spray drying (Bamidele et al., 2019). The objective of this study was to determine the stability of free and encapsulated ascorbyl palmitate in both normal and high amylose maize starch before and after pasting and spray drying with accelerated storage condition (40 °C, either UV light or dark environment) after which the antioxidant activities of the released ascorbyl palmitate was investigated.
was procured from Ingredion Incorporated® (Westchester-USA). Ascorbyl palmitate (AP), (CAS 137-66-6), pancreatic α- amylase (EC No 232-565-6); Type VI-B from porcine pancreas, (CAS 8049-47-6, 19.6 units/mg) were purchased from Sigma- Aldrich (St. Louis, MO. USA). All other reagents were of analytical grade.
2. Materials and methods
Thermal properties of the residue obtained after digesting the encapsulated ascorbyl palmitate in maize starch (normal and high amylose maize starch) with α-amylase for 180 min and dried were analysed using a high-pressure Differential Scanning Calorimetry (DSC) system with STARe® software (HP DSC827e, Mettler Toledo, Greifensee, Switzerland) according to the method of Wokadala, Ray, & Emmambux.
2.2. Methods Samples were pasted as reported by Bamidele et al. (2017) and samples were spray dried as reported by Bamidele et al. (2019). The whole pasted and spray dried samples were used (the samples contained both bound and unbound [free] ascorbyl palmitate). The samples containing the highest amount of ascorbyl palmitate were selected for storage stability (50 mg AP/g normal maize starch pasted, 200 mg AP/g normal and high amylose maize starch spray dried). The residue obtained after hydrolysis of the samples (50 mg AP/g normal maize starch pasted, 200 mg AP/g normal and high amylose maize starch spray dried) with α- amylase enzyme for 180 min from the previous studies (Bamidele et al., 2017, 2019) were analysed for presence of amylose-lipid complexes. The sample that contained an equal amount of ascorbyl palmitate in maize starch (normal and high amylose maize starch) without pasting and spray drying was used as a control (i.e. they were manually mixed in dry form). 2.3. Storage stability analysis (UV light, dark conditions, and hightemperature storage) Encapsulated ascorbyl palmitate (unwashed) was stored under UV light (16 W/cm2) or in the dark cupboard at 40 °C. About 50 mg of each sample was weighed in weighing boat in triplicate and stored for 12 weeks. The ascorbyl palmitate released from the stored samples were analysed at two weeks interval to determine the antioxidant activities using the ABTS radical scavenging method. Ascorbyl palmitate was released by hydrolysing encapsulated ascorbyl palmitate in α-amylase enzyme at 37 °C for 180 min. Unpasted and unsprayed samples as controls were subjected to the same storage conditions. 2.4. ABTS+ radical scavenging activity of the ligand The ABTS + radical scavenging activity of the released ascorbyl palmitate form the stored samples (50 mg ascorbyl palmitate in normal maize starch, 200 mg ascorbyl palmitate in normal maize starch and 200 mg ascorbyl palmitate in high amylose maize starch before and after pasting and spray drying), were determined using the procedure described by Bamidele et al. (2017). In brief, 7 mM ABTS + radical stock solution was prepared by mixing equal volumes of ABTS solution (8 mg ABTS in 1 ml water) and 2.45 mM potassium persulphate solution (prepared in water). The mixture was allowed to stand in the dark at room temperature for 12–16 h before use. Trolox standard solutions in methanol (0, 50, 100, 200, 400, 600 and 800 μmol TE/g) were prepared. Fresh ABTS + radical cation working solution was prepared by diluting ABTS + radical cation stock solution with PBS (pH 6.9) in a ratio of 1:29. Absorbance at 750 nm was measured using a Multiscan FC microplate reader (Thermo Fisher Scientific Waltham, MA, USA). Standard calibration curve of change in absorbance (x-axis) against Trolox concentration (y-axis) was plotted. Antioxidant activity was measured and expressed as μmol Trolox Equivalent per gram of sample. 2.5. Differential scanning calorimetry
2.1. Materials Commercial maize starch was obtained from Tongaat Hullet® (Edenvale, South Africa) and High amylose maize starch (Hylon VII®) 218
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(2012). Indium (Tp = 156.6 °C, heat flow = 28.45 J g − 1) was used to calibrate the instrument. Samples (approximately 10 mg db) were weighed separately into a crucible and about 30 ml distilled water was added. The pan was sealed and equilibrated for 24 h at 25 °C and heated from 25 °C to 140 °C at a rate of 10 °C/min under pressure (4 MPa). The reference material was an empty pan. The melting transition of the endotherm peak (onset temperature (To), peak temperature (Tp) and enthalpy (ΔH) were determined.
stored in the dark cupboard at 40 °C are shown in Fig. 1 (supplementary Table 1). Selection of the concentration (50 mg AP/g normal maize starch pasted and 200 mg AP/g normal and high amylose maize starch) was based on our previous findings (Bamidele et al., 2017, 2019). Various concentrations (15 & 50 mg AP/g starch) were used when ascorbyl palmitate was pasted with normal maize starch at 90 °C for 2 h. After pasting, it was found that the 92% of 15 mg AP was bound and 67.3% of 50 mg AP was bound with normal maize starch. The normal maize starch cannot absorb more ascorbyl palmitate because of the limited amylose present in the normal maize starch (Bamidele et al., 2017). Normal maize starch was only used for pasting because high amylose maize starch requires higher pasting temperature (130 °C) (Bamidele et al., 2017). This is because the high amylose maize starch cannot completely gelatinized or dispersed at pasting temperature at about 90 °C (Case et al., 1998). In our previous study, 15, 50, 100, and 200 mg of AP was spray dried with both normal and high amylose starch at 185 ± 1 °C for 1 min (Bamidele et al., 2019). After spray drying, it was found that the amount ascorbyl palmitate bound with normal and high amylose maize starch reduced with increase in the concentration of ascorbyl palmitate added. The encapsulation of ascorbyl palmitate occurred by both formation of amylose-ascorbyl palmitate complexes and entrapment of ascorbyl palmitate in starch matrix (Bamidele et al., 2019). A high dose was used for high amylose maize starch because it can form more amylose-lipid complexes with ascorbyl palmitate as it contained about 61.7% amylose (Ocloo, Minnaar & Emmambux, 2016) compared to 28.9% amylose for normal maize starch (Wokadala, Ray, & Emmambux, 2012). Therefore, the concentration, 50 mg AP/g normal maize starch pasted and 200 mg AP/g normal and high amylose maize starch were selected to relate this current work with our two previous ones (Bamidele et al., 2017, 2019). At week zero, the antioxidant activities of ascorbyl palmitate released before pasting/spray drying that contained 50, 200 and 200 mg of ascorbyl palmitate in normal and high amylose maize starch were 16.7, 60.6 and 59.6 μmol TE/g respectively. The antioxidant activities of released ascorbyl palmitate were similar (P > 0.05) throughout the remaining weeks of storage under the dark condition. The antioxidant activities of the released ascorbyl palmitate from pasted and spray dried maize starches after hydrolysis with α-amylase were low compared with antioxidant activities of free ascorbyl palmitate under dark storage conditions (Fig. 1). The antioxidant activities at week zero were 10.4 μmol TE/g for sample that contained 50 mg ascorbyl palmitate in maize starch (pasted), 38.7 μmol TE/g for sample that contained 200 mg ascorbyl palmitate in maize starch (spray dried) and 36.2 μmol TE/g for sample that contained 200 mg ascorbyl palmitate in high amylose maize starch. There was no significant difference
2.6. Confocal laser scanning microscopy (CLSM) Nile Red (Sigma-Aldrich) was used to stain free ascorbyl palmitate in both pasted and spray dried unwashed samples. Also, the residue obtained by digesting the samples with α-amylase for 180 min was stained with Nile Red. Nile Red dye (1 mg) was dissolved in 100 ml absolute ethanol to give 0.01% w/v aliquot of Nile Red solution. Maize starches (normal and high amylose maize starch) containing ascorbyl palmitate before and after pasting and spray drying (approximately 5 mg dry basis) was suspended in 1 ml 30% (v/v) glycerol solution and Nile Red dye were added before viewing under a microscope. The microscope slide containing the sample was observed using a Zeiss LSM 510 META Confocal Laser Scanning Microscope (Zeiss SMT, Jena, Germany) at 20X magnification. Plane neoflar100x and Numerical aperture (N.A) 1.4 was used for the images. The picture size was 512 × 512 pixels. The excitation and emission spectra for Nile Red dye were 488 nm and 550 nm, respectively. 2.7. Statistical analysis All experiments were repeated three times. Data were analysed using IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp. One-way analysis of variance (ANOVA) was performed to determine significant differences due to antioxidant activities of released ascorbyl palmitate by α-amylase from encapsulated maize starches (normal and high amylose maize starch) during pasting and spray drying. The means were separated using the least significant difference (LSD) test. 3. Results and discussion 3.1. Storage stability (Dark/UV light conditions and high-temperature storage) The antioxidant activities of free (unpasted and unsprayed dried) and released ascorbyl palmitate from encapsulated ascorbyl palmitate in maize starches (normal and high amylose maize starch) that were
Fig. 1. Effect of storage condition (dark and 40 °C) for 12 weeks on antioxidant activities of ascorbyl palmitate before and after pasting and spray drying with maize starches (normal and high amylose maize starch) over a period. (30–180 min). AP is Ascorbyl palmitate Keys A is 50 mg AP/g normal maize starch before pasting B is 200 mg AP/g normal maize starch before spray drying C is 200 mg AP/g high amylose maize starch before spray drying D is 50 mg AP/g normal maize starch after pasting E is 200 mg AP/g normal maize starch after spray drying F is 200 mg AP/g high amylose maize starch after spray drying Error bars represent standard deviation
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Fig. 2. Effect of storage condition (UV light and 40 °C) for 12 weeks on antioxidant activities of ascorbyl palmitate before and after pasting and spray drying with maize starches (normal and high amylose maize starch) over a period.(30–180 min). AP is Ascorbyl palmitate Keys A is 50 mg AP/g normal maize starch before pasting B is 200 mg AP/g normal maize starch before spray drying C is 200 mg AP/g high amylose maize starch before spray drying D is 50 mg AP/g normal maize starch after pasting E is 200 mg AP/g normal maize starch after spray drying F is 200 mg AP/g high amylose maize starch after spray drying
degradation of free (before pasting and spray drying) ascorbyl palmitate (Fig. 3A–C) seems to follow the 1 st order kinetic reaction, showing a fast reaction rate. This is typical of oxidation of fat that is usually shows exponential degradation under light conditions (Špiclin et al., 2001). The antioxidant activity of ascorbyl palmitate released from the pasted and spray dried starches with ascorbyl palmitate stored under UV light for 12 weeks did not show a first order decrease. The antioxidant activities of the released ascorbyl palmitate for samples that contained 50 and 200 mg of ascorbyl palmitate in normal maize starch were 10.4 and 38.7 (μmol TE/g) while that of 200 mg ascorbyl palmitate in high amylose maize starch was 36.2 (μmol TE/g) at week zero (Fig. 3). There was no significant difference (P > 0.05) in reduction observed in the antioxidant activities during the storage period of 12 weeks, and this was also similar to those when stored in the dark condition. The stability of ascorbyl palmitate released from the encapsulated sample may be attributed to encapsulation that may have prevented photo-oxidation, and thus no degradation of ascorbyl palmitate. The reduction in antioxidant activities of ascorbyl palmitate stored under UV light observed after the sixth week may be due to oxidative degradation of ascorbyl palmitate to 2, 3-diketogulonic acid has reported by Giuffrida et al. (2007). Oxidative degradation has been reported to be facilitated by UV light, and this consequently speeds up the rate of oxidation of ascorbyl palmitate. In photo-oxidation, UV light is absorbed by ascorbyl palmitate thereby creating an electron-hole pair. Electron-hole pair generates free radicals (RO·) that can undergo secondary reactions to create more free radicals (Kondrakov et al., 2014).
(P > 0.05) in the antioxidant activities of all the samples at the beginning and after the 12th week of storage under dark conditions. The stability of free ascorbyl palmitate stored in dark cupboard at 40 °C observed in this research may be due to the absence of UV light and little amount of oxygen, which cannot cause detectable oxidative degradation of free ascorbyl palmitate. In addition, the ability of ascorbyl palmitate to withstand higher temperature contributed to the stability of free ascorbyl palmitate during storage (Gwo, Flick, Dupuy, Ory, & Baran, 1985). This result was similar to the result of Alborzi, Lim, and Kakuda, (2013) who reported stability of encapsulated folic acid (in mixture of low viscosity sodium alginate pectin and medium viscosity sodium alginate pectin) stored in the dark condition at pH 3 and 25 °C temperature for 41 days. Fig. 2 (supplementary Table 2) shows the antioxidant activities of free (non-encapsulated: before pasting/spray drying) and the released ascorbyl palmitate from encapsulated ascorbyl palmitate in normal and high amylose maize starch stored under UV light at 40 °C. The antioxidant activities of the free ascorbyl palmitate were higher than that of the released ascorbyl palmitate after enzymatic hydrolysis of encapsulated ligand at week zero. The release ascorbyl palmitate from unpasted that contained 50 mg ascorbyl palmitate stored under light condition (UV light) lost its antioxidant activity after 6 weeks of storage. The samples that contained 200 mg of free ascorbyl palmitate in maize starches (normal and high amylose maize starch before spray drying) stored under the same condition (UV light) had negligible scavenging power by the 12th week of storage (0.4 μmol TE/g) compared to a high scavenging power at week zero (60.6 μmol TE/g). The
Fig. 3. DSC thermogram of residues obtained after hydrolysing encapsulated AP in maize starches (normal and high amylose maize starch) with α-amylase enzyme for 180 min. AP = Ascorbyl Palmitate Keys A is control sample (residue obtained from normal maize starch pasted without ascorbyl palmitate) B is residue obtained from enzymatic hydrolysis of 50 mg AP/g normal maize starch pasted C is residue obtained from enzymatic hydrolysis 200 mg AP/g normal maize starch spray dried D is residue obtained from enzymatic hydrolysis 200 mg AP/g high amylose maize starch spray dried
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Encapsulation of ascorbyl palmitate in normal and high amylose maize starch may prevent photo-oxidation reaction of ascorbyl palmitate in starch by preventing the absorption of UV light and preventing the creation of electron-hole pair. This is because ascorbyl palmitate has formed complexes with amylose during pasting and spray drying. The fatty acid moiety of ascorbyl palmitate is trapped inside the amylose helical structure and is not available for interaction with UV light. Bamidele et al. (2017, 2019) reported that the antioxidant activities of the released ascorbyl palmitate are directly proportional to the amount released. The antioxidant activities of released ascorbyl palmitate from encapsulated ascorbyl palmitate during pasting and stored under dark and UV light conditions were 9.4 & 9.5 μmol TE/g. This result was similar to the report of Bamidele et al. (2017) reported that the antioxidant activity of ascorbyl palmitate released from pasted unwashed sample was 9.6 μmol TE/g. The antioxidant activity of released ascorbyl palmitate from unwashed spray dried samples stored under dark and UV light at 40 °C were 39.2 & 35.4 μmol TE/g, and 39.6 & 36.5 μmol TE/g respectively. The results were also similar to Bamidele et al. (2019) who found that the antioxidant activity of released ascorbyl palmitate from encapsulated ascorbyl palmitate was 40.4 μmol TE/g from normal maize starch and 37.4 μmol TE/g from high normal maize starch. This suggests that similar amount of ascorbyl palmitate were released in the current shelf life study compared to those reported by Bamidele et al. (2017, 2019) During incubation time (180 min) with the α-amylase enzyme, there seems to be a limited release of ascorbyl palmitate. It has been reported that amylose-lipid complexes are resistant to α-amylase digestion (Eerlingen & Delcour, 1995). Bound ascorbyl palmitate is expected to be released in the large intestine by microbial fermentation in the large intestine (William et al., 2001). Louis, Scott, Duncan, and Flint, (2007) reported that non-digestible components such as resistance starch that escape digestion by the endogenous enzymes in upper gastrointestinal tract becomes available as substrates in the large intestine for microbial fermentation. The antioxidant activities for week zero of the sample that contained 200 mg ascorbyl palmitate in spray-dried normal and high amylose starch differed despite having the same amount of ascorbyl palmitate. This may be due to more formation of amylose-lipid complexes by high amylose maize starch due to higher content of amylose present in the maize. Ocloo et al. (2016) reported the amylose content of high amylose maize starch (HYLON VII) to be 62%. They reported an increase in second peak viscosity when stearic acid was pasted with high amylose maize. The DSC results of our previous study (Bamidele et al., 2019) also showed higher enthalpy (ΔH) (5.9 J/g) for amyloselipid complexes formed with high amylose maize starch than amyloselipid complexes formed with normal maize starch (3.5 J/g). The higher enthalpy suggests higher amount of complex formed during spray drying of high amylose maize starch with ascorbyl palmitate compared normal maize starch.
Table 1 Endothermic peak value of residues of encapsulated AP in normal and high amylose maize starch after hydrolysis with α-amylase enzyme for 180 min. Samples
To °C
Tp °C
Tc °C
ΔH (J/g)
A B C D
ND 90.3a ± 0.5 91.4b ± 0.3 91.5b ± 0.4
ND 97.7a ± 0.3 98.9b ± 0.4 99.2b ± 0.5
ND 102.1a ± 0.7 109.4b ± 0.9 109.8b ± 1.1
ND 2.2a ± 0.2 4.9b ± 0.3 4.9b ± 0.3
Values within same columns with different letters are significantly different (p < 0.05). ND is not detected, AP- Ascorbyl palmitate. Keys A is control sample (residue obtained from normal maize starch pasted without ascorbyl palmitate). B is residue obtained from enzymatic hydrolysis of 50 mg AP/g normal maize starch pasted. C is residue obtained from enzymatic hydrolysis 200 mg AP/g normal maize starch spray dried. D is residue obtained from enzymatic hydrolysis 200 mg AP/g high amylose maize starch spray dried.
temperature of 99.2 °C and enthalpy of 4.9 J/g. All the residue samples obtained after α-amylase hydrolysis for 180 min of encapsulated ascorbyl palmitate in normal maize starch during pasting and encapsulated ascorbyl palmitate in both normal and high amylose maize starch during spray drying, showed type I amyloselipid complexes. Amylose-lipid complexes is formed due to hydrophobic interaction within the helical cavity of amylose and hydrocarbon chain of lipid compounds (Immel & Lichtenthaler, 2000). The amylose chain shows a characteristic turn (natural twist) giving a helical adaptation with six anhydroglucose unit per turn. When the fatty acid ester (ascorbyl palmitate) was added to the system during pasting or spray drying, the hydrocarbon chain of palmitate part of ascorbyl palmitate can enter hydrophobic cavity to form amylose-ascorbyl palmitate complexes. Type I amylose lipid complexes are formed at 60 °C and have melting temperatures of about 98 °C (Biliaderis & Galloway, 1989). Other authors also found the melting of type I amylose lipidcomplexes at 100 °C (Biliaderis, Page, Slade, & Sirett, 1985; Biliaderis & Galloway, 1989). The melting endotherms at 98–99? C (Fig. 3 and Table 1) thus showed the presence of type I amylose-lipids complexes in the residues obtained after enzymatic hydrolysis of starch used to encapsulate ascorbyl palmitate. Amylose-lipid complexes type II was formed when normal maize starch was pasted with ascorbyl palmitate (Bamidele et al., 2017). This was attributed to long pasting time and has been reported by Wokadala et al. (2012). Amylose-lipid complexes type I was observed in the residue obtained after hydrolysing the pasted sample containing 50 mg AP/g normal maize starch and spray dried samples containing 200 mg AP/g in normal and high amylose maize starch. Amylose-lipid complexes type I observed in the residues may be attributed to the effect of the α-amylase enzyme that has converted type II amylose-lipid complexes to type I amylose-lipid complexes. This may be possible because of the prolonged incubation time (180 min) of amylose-lipid complexes type II with the α-amylase enzyme, which attacked the exposed α-1-4 glycosidic bond present in the amorphous region of type II amyloselipid complexes. Obiro, Sinha Ray, and Emmambux, (2012) and Gelders, Duyck, Goesaert, and Delcour, (2005) showed the postulated diagram of V-amylose type II complex morphology. They suggested that type II amylose-lipid complexes occurred as semi-crystalline structure linked by amorphous region. The amylose lipid complexes as type II are rod like structures parallel to each other and linked at the end of the rod by amorphous region to form a higher molecular order structure with higher melting point. It can be postulated that the bonds (α-1-4 glycosidic bond) of the amylose molecule is exposed in the amorphous region, thus they are hydrolysed by the enzyme (α-amylase) during incubation to disturb the higher molecular order structure, thereby
3.2. Differential scanning calorimetry of residue from digested samples Fig. 3 and Table 1 show the results of differential scanning calorimetry of the residues obtained after enzymatic hydrolysis of pasted and spray dried starches with ascorbyl palmitate. All the residues obtained from the hydrolysed samples (50 mg AP/g starch, pasted, 200 mg AP/g normal maize starch spray dried and 200 mg AP/ g high amylose maize starch spray dried) showed one endothermic peak except the control sample (no peak) without ascorbyl palmitate. The residue obtained from a sample that contained 50 mg ascorbyl palmitate pasted with normal maize starch has one endothermic peak with a peak temperature of 97.7 °C and enthalpy of 2.2 J/g. The residue obtained from a sample that contained 200 mg ascorbyl palmitate spray dried with normal maize starch has the peak temperature of 98.9 °C and enthalpy of 4.9 J/g. The residue obtained from spray-dried sample containing 200 mg ascorbyl palmitate in high amylose maize starch has the peak 221
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Fig. 4. CLSM images of washed (pasted and spray dried) samples, and residues obtained from digested encapsulated AP in starches (native maize starch and high amylose maize starch) using α-amylase enzyme. Each bar- 20X, Y is starch matrix and X is ascorbyl palmitate AP- Ascorbyl palmitate NMS – Normal maize starch HAMS – High amylose maize starch
UV light conditions at 40 °C, but free ascorbyl palmitate (Non-encapsulated) is degraded under UV light in respect to their antioxidant activities. The rate of starch hydrolysis of encapsulated ascorbyl palmitate in maize starches (normal maize starch and high amylose maize starch) is partial and the residue from the entire hydrolysed sample still contain some ascorbyl palmitate.
leading to type I amylose-lipid complexes observed in the residues of the hydrolysed samples. 3.3. Confocal laser scanning microscopy The confocal laser scanning micrograph (CLSM) of the samples (200 mg ascorbyl palmitate in normal maize starch and 200 mg ascorbyl palmitate in high amylose starch) before enzymatic hydrolysis fluorescence while after enzymatic hydrolysis showed no fluorescence (Fig. 4). Fluorescence observed before enzymatic hydrolysis may be due to the interaction between ascorbyl palmitate that was trapped in the starch matrix and Nile Red dye used to stain the sample. The absence of fluorescence from the same sample (residue of 200 mg ascorbyl palmitate in normal and high amylose starch) after enzymatic hydrolysis may be attributed to unavailability of ascorbyl palmitate to interact with Nile Red dye used to stain the sample. Nile red interacts with the free fatty acid component of ascorbyl palmitate. However, this was not the case in this study for the non-hydrolysed residues as the fatty acid component of ascorbyl palmitate was probably inside the amylose helical structure. In other studies, Bamidele et al. (2019) reported fluorescence when Nile red dye was added to a mixture maize starch and ascorbyl palmitate before spray drying. This was due to availability of free ascorbyl palmitate to Nile Red dye after spray drying and the free ascorbyl palmitate was washed off, there was no fluorescence of ascorbyl palmitate because of the complexation of ascorbyl palmitate with amylose to form amylose-ascorbyl palmitate complexes or the ascorbyl palmitate was physically entrapped. The DSC and CLSM results show that the residue obtained from the hydrolysed encapsulated ascorbyl palmitate, which is inferred to reach the large intestine after escaping the upper gastrointestinal tract, contains ascorbyl palmitate. This could provide potential health benefit due to the antioxidant properties of ascorbyl palmitate. The report of Williams, Verstegen, Tamminga, and 2001 reported that fermentation of resistant starch (e.g. amylose-lipid complexes) in the large intestine by the microflora is possible since some of the undigested dietary components will move from the small intestine into the large intestine.
Acknowledgements The authors would like to acknowledge the National Research Foundation (NRF) and DST/NRF Centre of Excellence in Food Security and University of Pretoria for funding the research work. Appendix A. Supplementary data Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.carbpol.2019.04.022. References Alborzi, S., Lim, L. T., & Kakuda, Y. (2013). Encapsulation of folic acid and its stability in sodium alginate-pectin-poly (ethylene oxide) electrospun fibres. Journal of Microencapsulation, 30(1), 64–71. Bakowska-Barczak, A. M., & Kolodziejczyk, P. P. (2011). Black currant polyphenols: Their storage stability and microencapsulation. Industrial Crops and Products, 34(2), 1301–1309. Bamidele, O. P., Duodu, K. G., & Emmambux, M. N. (2017). Encapsulation and antioxidant activity of ascorbyl palmitate with maize starch during pasting. Carbohydrate Polymers, 166, 202–208. Bamidele, O. P., Duodu, K. G., & Emmambux, M. N. (2019). Encapsulation and antioxidant activity of ascorbyl palmitate with normal and high amylose maize starch by spray drying. Food Hydrocolloids, 86, 124–133. Biliaderis, C. G., & Galloway, G. (1989). Crystallization behavior of amylose-V complexes: Structure-property relationships. Carbohydrate Research, 189, 31–48. Biliaderis, C. G., Page, C. M., Slade, L., & Sirett, R. R. (1985). Thermal behavior of amylose-lipid complexes. Carbohydrate Polymers, 5(5), 367–389. Carstensen, J. T. (2000). Oxidation in solution. In J. T. Carstensen, & C. T. Rhodes (Eds.). Drug stability, principles, and practices (pp. 113–131). New York: Dekker. Case, S. E., Capitani, T., Whaley, J. K., Shi, Y. C., Trzasko, P., Jeffcoat, R., et al. (1998). Physical properties and gelation behavior of a low-amylopectin maize starch and other high-amylose maize starches. Journal of Cereal Science, 27(3), 301–314. 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, 4212–4218. Dima, Ş., Dima, C., & Iordăchescu, G. (2015). Encapsulation of functional lipophilic food and drug biocomponents. Food Engineering Reviews, 7, 417–438. Dries, D. M., Knaepen, L., Goderis, B., & Delcour, J. A. (2017). Encapsulation of the antioxidant ascorbyl palmitate in V-type granular cold-water swelling starch affects the properties of both. Carbohydrate Polymers, 165, 402–409.
4. Conclusions Encapsulated ascorbyl palmitate by formation of amylose lipid inclusion complexes makes the ligand stable when stored in the dark and 222
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of encapsulated sour cherry phenolic compounds prepared from micro-and nanosuspensions. Food and Bioprocess Technology, 7(1), 204–211. Munin, A., & Edwards-Lévy, F. (2011). Encapsulation of natural polyphenolic compounds; a review. Pharmaceutics, 3(4), 793–829. Obiro, W. C., Sinha Ray, S., & Emmambux, M. N. (2012). V-amylose structural characteristics, methods of preparation, significance, and potential applications. Food Reviews International, 28, 412–438. Ocloo, F. C., Minnaar, A., & Emmambux, N. M. (2016). Effects of stearic acid and gamma irradiation, alone and in combination, on pasting properties of high amylose maize starch. Food Chemistry, 190, 12–19. Saénz, C., Tapia, S., Chávez, J., & Robert, P. (2009). Microencapsulation by spray drying of bioactive compounds from cactus pear (Opuntia ficus-indica). Food Chemistry, 114(2), 616–622. Singh, S., & Bakshi, M. (2000). Stress test to determine the inherent stability of drugs. Pharmaceutical Technology, 4, 1–14. Špiclin, P., Gašperlin, M., & Kmetec, V. (2001). Stability of ascorbyl palmitate in topical microemulsions. International Journal of Pharmaceutics, 222, 271–279. Williams, B. A., Verstegen, M. W., & Tamminga, S. (2001). Fermentation in the large intestine of single-stomached animals and its relationship to animal health. Nutrition Research Reviews, 14(2), 207–228. Wokadala, O. C., Ray, S. S., & Emmambux, M. N. (2012). The occurrence of amylose-lipid complexes in teff and maize starch biphasic pastes. Carbohydrate Polymers, 90, 616–622. Yuan, J. P., & Chen, F. (1998). Degradation of ascorbic acid in aqueous solution. Journal of Agricultural and Food Chemistry, 46(12), 5078–5082. Zhou, M., Li, X., Li, Y., Yao, Q. E., Ming, Y., Li, Z., et al. (2017). Ascorbyl palmitateincorporated paclitaxel-loaded composite nanoparticles for synergistic anti-tumoral therapy. Drug Delivery, 24(1), 1230–1242.
Eerlingen, R. C., & Delcour, J. A. (1995). Formation, analysis, structure, and properties of type III enzyme resistant starch. Journal of Cereal Science, 22, 129–138. Gelders, G. G., Duyck, J. P., Goesaert, H., & Delcour, J. A. (2005). Enzyme and acid resistance of amylose-lipid complexes differing in amylose chain length, lipid and complexation temperature. Carbohydrate Polymers, 60, 379–389. Giuffrida, F., Destaillats, F., Egart, M. H., Hug, B., Golay, P. A., Skibsted, L. H., et al. (2007). Activity and thermal stability of antioxidants by differential scanning calorimetry and electron spin resonance spectroscopy. Food Chemistry, 101, 1108–1114. Gwo, Y. Y., Flick, G. J., Jr., Dupuy, H. P., Ory, R. L., & Baran, W. L. (1985). Effect of ascorbyl palmitate on the quality of frying fats for deep frying operations. Journal of the American Oil Chemists’ Society, 62, 1666–1671. Immel, S., & Lichtenthaler, F. W. (2000). The hydrophobic topographies of amylose and its blue iodine complex. Starch-Stärke, 52(1), 1–8. Jafari, S. M., Assadpoor, E., He, Y., & Bhandari, B. (2008). Encapsulation efficiency of food flavours and oils during spray drying. Drying Technology, 26, 816–835. Kondrakov, A. O., Ignatev, A. N., Frimmel, F. H., Bräse, S., Horn, H., & Revelsky, A. I. (2014). Formation of genotoxic quinones during bisphenol A degradation by TiO 2 photocatalysis and UV photolysis: A comparative study. Applied Catalysis B, Environmental, 160, 106–114. Kong, L., & Ziegler, G. R. (2014). Molecular encapsulation of ascorbyl palmitate in preformed V-type starch and amylose. Carbohydrate Polymers, 111, 256–263. Lalush, I., Bar, H., Zakaria, I., Eichler, S., & Shimoni, E. (2005). Utilization of amylose−Lipid complexes as molecular nanocapsules for conjugated linoleic acid. Biomacromolecules, 6, 121–130. Louis, P., Scott, K. P., Duncan, S. H., & Flint, H. J. (2007). Understanding the effects of diet on bacterial metabolism in the large intestine. Journal of Applied Microbiology, 102, 1197–1208. Luca, A., Cilek, B., Hasirci, V., Sahin, S., & Sumnu, G. (2014). Storage and baking stability
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Storage stability of encapsulated ascorbyl palmitate in normal and high amylose maize starches during pasting and spray dryin O.P. Bamidele, M.N. Emmambux
T
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Department of Consumer and Food Sciences, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
A R T I C LE I N FO
A B S T R A C T
Keywords: Encapsulation Spray drying High amylose maize starch Ascorbyl palmitate
This study determines storage stability and release of encapsulated ascorbyl palmitate in normal and high amylose maize starch by pasting and spray drying. The amount of ascorbyl palmitate released was analysed in the stored samples (dark cupboard, and under UV light at a temperature of 40 °C for 12 weeks) and their antioxidant activity determined. Storage of encapsulated ascorbyl palmitate at 40 °C under both dark and UV light conditions did not affect the amount release and the ability to scavenge the free radical (ABTS+). However, the antioxidant activity of free ascorbyl palmitate exponentially decreased at 40 °C under UV light condition. The analysed residues after α-amylase digestion of encapsulated ascorbyl palmitate showed some endothermic peaks, suggesting that amylose-lipids complexes formed were resistant to α-amylase digestion. Encapsulation of ascorbyl palmitate in maize starch may improve its storage stability under light (UV) conditions.
1. Introduction Storage stability of functional foods is considered a critical requirement before such food products are sold in the market. Storage stability is necessary to ensure the efficacy of the bioactive compounds in functional foods under different storage conditions and during the shelf life (Singh & Bakshi, 2000). The potency of ascorbyl palmitate has been found to reduce during storage conditions such as under light and in the presence of oxygen (Špiclin, Gašperlin, & Kmetec, 2001), also in stomach conditions (Yuan & Chen, 1998). Encapsulation of bioactive compounds have been found to improve their stability (Saénz, Tapia, Chávez, & Robert, 2009). Encapsulation of bioactive compounds are carried out with different methods. These methods can be categorised as (i) physical method for example Spray drying, (ii) physico-chemical method for example complex coacervation, hydrophobic interaction, cooling of emulsion, solvent removal, ionic gelation, extrusion cooking, electrospinning, and acid precipitation, (iii) chemical method for example in situ polymerization, interfacial polycondensation and interfacial cross-linking (Munin & Edwards-Lévy, 2011). Encapsulation by polymeric carriers is an approach widely used to preserve bioactive compounds. In addition to the preservation effects, it may control the release or delivery of the encapsulated or entrapped ingredients thereby improving their bioavailability in humans (Dima, Dima, & Iordăchescu, 2015). Encapsulation of an insoluble substance
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may improve its dispersion rate and storage stability, and this often may result in the bioavailability of the insoluble substance being enhanced (Dima et al., 2015). Encapsulation of bioactive compound such as genistein (Cohen, Orlova, Kovalev, Ungar, & Shimoni, 2008), flavour compounds (Jafari, Assadpoor, He, & Bhandari, 2008), phenolic compounds (Lalush, Bar, Zakaria, Eichler, & Shimoni, 2005) has been achieved with the use of normal and high amylose maize starch and other materials like fish oil. Kong and Ziegler (2014) encapsulated ascorbyl palmitate in amylose and high amylose maize starch by annealing (Heating of starch and amylose in aqueous ethanol at different temperature for 10 min) and use of DMSO (dimethyl sulphur oxide). They reported encapsulation of ascorbyl palmitate in both amylose and starch. Ascorbyl palmitate was also encapsulated in solid lipid nanoparticles (made from Glycery monostearate and paclitaxel (PTX) by Zhou et al. (2017). The encapsulation of ascorbyl palmitate in paclitaxel and solid lipid nanoparticle had a synergistic effect to suppress tumour cell growth murine B16F10 melanoma that had metastasized to the lungs of mice in suppressing tumour growth in murine B16F10-bearing mice and in eliminating cancer cells in the lungs as compared to the single drug alone. In our recent work, we have shown that ascorbyl palmitate was encapsulated in normal maize starch by formation of amylose-ascorbyl palmitate complexes after pasting at 90°C for 2 h (Bamidele, Duodu, & Emmambux, 2017). Ascorbyl palmitate was also encapsulated in both normal and high amylose maize starch during spray drying
Corresponding author. E-mail address: [email protected] (M.N. Emmambux).
https://doi.org/10.1016/j.carbpol.2019.04.022 Received 6 December 2018; Received in revised form 25 March 2019; Accepted 4 April 2019 Available online 09 April 2019 0144-8617/ © 2019 Elsevier Ltd. All rights reserved.
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(185 ± 1°C) through the formation of amylose-ascorbyl palmitate complexes and entrapment in a starch matrix (Bamidele, Duodu, & Emmambux, 2019). Dries, Knaepen, Goderis, and Delcour, (2017) also encapsulated ascorbyl palmitate to form V-type granular cold-water swelling starch (GCWSS) using both maize and potato starches. Encapsulation enabled partial release of ascorbyl palmitate when hydrolysed with α-amylase for 180 min and this suggests that some of the encapsulated ascorbyl palmitate may reach the large intestine. Špiclin et al. (2001) reported stability of antioxidant activities of encapsulated ascorbyl palmitate in different micro-emulsion (Capric triglyceride, Mygliol 812 and Labrasol) during storage at 25 °C in a dark container. Best to our knowledge, there is no reported literature on stability during storage for encapsulated ascorbyl palmitate in maize starch that form amylose lipid complexes. Stability of other encapsulated bioactive compounds for example microencapsulated polyphenolic compounds that provide antioxidant properties during storage have been studied. Bakowska-Barczak and Kolodziejczyk (2011) studied the stability of microencapsulated black currant polyphenols during storage for 12 months at 8 °C and 25 °C. They reported that the antioxidant activity of released microencapsulated black currant polyphenol in maltoderin DE11 during 12 months storage at 8 °C and 25 °C in brown bottle was similar to natural black currant polyphenol before encapsulation, but those that were not encapsulated showed reduction in antioxidant activity. This shows that there was no degradation of the bioactive compounds (black currant polyphenol) during storage when compared with non-encapsulated black currant polyphenol that degraded during storage. Similarly, Luca, Cilek, Hasirci, Sahin, and Sumnu, (2014) determined the stability of encapsulated sour cherry phenolic compounds in mixture of maltodextrin and gum Arabic (8% maltodectrin to 2% gum Arabic) during storage at 43% relative humidity for 48 h and used in a food system. They reported a loss of 37% of antioxidant activity of non-encapsulated extracted crude phenolic compounds and 43% loss of antioxidant activities from extracted and purified non-encapsulated phenolic compounds during storage. In comparison, there was 10% loss of the antioxidant activities of extracted phenolic compounds and 15% loss of antioxidant activities of extracted purified phenolic compounds during storage when the phenolic compounds were microencapsulated. The degradation of free ascorbyl palmitate is due to the effects of the oxidative reaction catalyzed by a metal ion or light (Špiclin et al., 2001). Oxidative degradation occurs more in dilute systems, indicating that the initial concentration of the ascorbyl palmitate is an important factor that contributes to the extent of degradation (Carstensen, 2000). The storage stability of encapsulated ascorbyl palmitate through determination of antioxidant activity is required to assess the efficacy of the guest molecule (ascorbyl palmitate). This would also help elucidate the effect of different storage conditions on the shelf life and antioxidant activities of encapsulated ascorbyl palmitate. The hypothesis is that encapsulated ascorbyl palmitate in maize starches (normal and high amylose maize starch) is expected to be stable under light (UV) and dark condition at accelerated temperature of 40 °C because ascorbyl palmitate formed a amylose-ascorbyl palmitate complexes with amylose during pasting (Bamidele et al., 2017) or spray drying (Bamidele et al., 2019). The objective of this study was to determine the stability of free and encapsulated ascorbyl palmitate in both normal and high amylose maize starch before and after pasting and spray drying with accelerated storage condition (40 °C, either UV light or dark environment) after which the antioxidant activities of the released ascorbyl palmitate was investigated.
was procured from Ingredion Incorporated® (Westchester-USA). Ascorbyl palmitate (AP), (CAS 137-66-6), pancreatic α- amylase (EC No 232-565-6); Type VI-B from porcine pancreas, (CAS 8049-47-6, 19.6 units/mg) were purchased from Sigma- Aldrich (St. Louis, MO. USA). All other reagents were of analytical grade.
2. Materials and methods
Thermal properties of the residue obtained after digesting the encapsulated ascorbyl palmitate in maize starch (normal and high amylose maize starch) with α-amylase for 180 min and dried were analysed using a high-pressure Differential Scanning Calorimetry (DSC) system with STARe® software (HP DSC827e, Mettler Toledo, Greifensee, Switzerland) according to the method of Wokadala, Ray, & Emmambux.
2.2. Methods Samples were pasted as reported by Bamidele et al. (2017) and samples were spray dried as reported by Bamidele et al. (2019). The whole pasted and spray dried samples were used (the samples contained both bound and unbound [free] ascorbyl palmitate). The samples containing the highest amount of ascorbyl palmitate were selected for storage stability (50 mg AP/g normal maize starch pasted, 200 mg AP/g normal and high amylose maize starch spray dried). The residue obtained after hydrolysis of the samples (50 mg AP/g normal maize starch pasted, 200 mg AP/g normal and high amylose maize starch spray dried) with α- amylase enzyme for 180 min from the previous studies (Bamidele et al., 2017, 2019) were analysed for presence of amylose-lipid complexes. The sample that contained an equal amount of ascorbyl palmitate in maize starch (normal and high amylose maize starch) without pasting and spray drying was used as a control (i.e. they were manually mixed in dry form). 2.3. Storage stability analysis (UV light, dark conditions, and hightemperature storage) Encapsulated ascorbyl palmitate (unwashed) was stored under UV light (16 W/cm2) or in the dark cupboard at 40 °C. About 50 mg of each sample was weighed in weighing boat in triplicate and stored for 12 weeks. The ascorbyl palmitate released from the stored samples were analysed at two weeks interval to determine the antioxidant activities using the ABTS radical scavenging method. Ascorbyl palmitate was released by hydrolysing encapsulated ascorbyl palmitate in α-amylase enzyme at 37 °C for 180 min. Unpasted and unsprayed samples as controls were subjected to the same storage conditions. 2.4. ABTS+ radical scavenging activity of the ligand The ABTS + radical scavenging activity of the released ascorbyl palmitate form the stored samples (50 mg ascorbyl palmitate in normal maize starch, 200 mg ascorbyl palmitate in normal maize starch and 200 mg ascorbyl palmitate in high amylose maize starch before and after pasting and spray drying), were determined using the procedure described by Bamidele et al. (2017). In brief, 7 mM ABTS + radical stock solution was prepared by mixing equal volumes of ABTS solution (8 mg ABTS in 1 ml water) and 2.45 mM potassium persulphate solution (prepared in water). The mixture was allowed to stand in the dark at room temperature for 12–16 h before use. Trolox standard solutions in methanol (0, 50, 100, 200, 400, 600 and 800 μmol TE/g) were prepared. Fresh ABTS + radical cation working solution was prepared by diluting ABTS + radical cation stock solution with PBS (pH 6.9) in a ratio of 1:29. Absorbance at 750 nm was measured using a Multiscan FC microplate reader (Thermo Fisher Scientific Waltham, MA, USA). Standard calibration curve of change in absorbance (x-axis) against Trolox concentration (y-axis) was plotted. Antioxidant activity was measured and expressed as μmol Trolox Equivalent per gram of sample. 2.5. Differential scanning calorimetry
2.1. Materials Commercial maize starch was obtained from Tongaat Hullet® (Edenvale, South Africa) and High amylose maize starch (Hylon VII®) 218
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(2012). Indium (Tp = 156.6 °C, heat flow = 28.45 J g − 1) was used to calibrate the instrument. Samples (approximately 10 mg db) were weighed separately into a crucible and about 30 ml distilled water was added. The pan was sealed and equilibrated for 24 h at 25 °C and heated from 25 °C to 140 °C at a rate of 10 °C/min under pressure (4 MPa). The reference material was an empty pan. The melting transition of the endotherm peak (onset temperature (To), peak temperature (Tp) and enthalpy (ΔH) were determined.
stored in the dark cupboard at 40 °C are shown in Fig. 1 (supplementary Table 1). Selection of the concentration (50 mg AP/g normal maize starch pasted and 200 mg AP/g normal and high amylose maize starch) was based on our previous findings (Bamidele et al., 2017, 2019). Various concentrations (15 & 50 mg AP/g starch) were used when ascorbyl palmitate was pasted with normal maize starch at 90 °C for 2 h. After pasting, it was found that the 92% of 15 mg AP was bound and 67.3% of 50 mg AP was bound with normal maize starch. The normal maize starch cannot absorb more ascorbyl palmitate because of the limited amylose present in the normal maize starch (Bamidele et al., 2017). Normal maize starch was only used for pasting because high amylose maize starch requires higher pasting temperature (130 °C) (Bamidele et al., 2017). This is because the high amylose maize starch cannot completely gelatinized or dispersed at pasting temperature at about 90 °C (Case et al., 1998). In our previous study, 15, 50, 100, and 200 mg of AP was spray dried with both normal and high amylose starch at 185 ± 1 °C for 1 min (Bamidele et al., 2019). After spray drying, it was found that the amount ascorbyl palmitate bound with normal and high amylose maize starch reduced with increase in the concentration of ascorbyl palmitate added. The encapsulation of ascorbyl palmitate occurred by both formation of amylose-ascorbyl palmitate complexes and entrapment of ascorbyl palmitate in starch matrix (Bamidele et al., 2019). A high dose was used for high amylose maize starch because it can form more amylose-lipid complexes with ascorbyl palmitate as it contained about 61.7% amylose (Ocloo, Minnaar & Emmambux, 2016) compared to 28.9% amylose for normal maize starch (Wokadala, Ray, & Emmambux, 2012). Therefore, the concentration, 50 mg AP/g normal maize starch pasted and 200 mg AP/g normal and high amylose maize starch were selected to relate this current work with our two previous ones (Bamidele et al., 2017, 2019). At week zero, the antioxidant activities of ascorbyl palmitate released before pasting/spray drying that contained 50, 200 and 200 mg of ascorbyl palmitate in normal and high amylose maize starch were 16.7, 60.6 and 59.6 μmol TE/g respectively. The antioxidant activities of released ascorbyl palmitate were similar (P > 0.05) throughout the remaining weeks of storage under the dark condition. The antioxidant activities of the released ascorbyl palmitate from pasted and spray dried maize starches after hydrolysis with α-amylase were low compared with antioxidant activities of free ascorbyl palmitate under dark storage conditions (Fig. 1). The antioxidant activities at week zero were 10.4 μmol TE/g for sample that contained 50 mg ascorbyl palmitate in maize starch (pasted), 38.7 μmol TE/g for sample that contained 200 mg ascorbyl palmitate in maize starch (spray dried) and 36.2 μmol TE/g for sample that contained 200 mg ascorbyl palmitate in high amylose maize starch. There was no significant difference
2.6. Confocal laser scanning microscopy (CLSM) Nile Red (Sigma-Aldrich) was used to stain free ascorbyl palmitate in both pasted and spray dried unwashed samples. Also, the residue obtained by digesting the samples with α-amylase for 180 min was stained with Nile Red. Nile Red dye (1 mg) was dissolved in 100 ml absolute ethanol to give 0.01% w/v aliquot of Nile Red solution. Maize starches (normal and high amylose maize starch) containing ascorbyl palmitate before and after pasting and spray drying (approximately 5 mg dry basis) was suspended in 1 ml 30% (v/v) glycerol solution and Nile Red dye were added before viewing under a microscope. The microscope slide containing the sample was observed using a Zeiss LSM 510 META Confocal Laser Scanning Microscope (Zeiss SMT, Jena, Germany) at 20X magnification. Plane neoflar100x and Numerical aperture (N.A) 1.4 was used for the images. The picture size was 512 × 512 pixels. The excitation and emission spectra for Nile Red dye were 488 nm and 550 nm, respectively. 2.7. Statistical analysis All experiments were repeated three times. Data were analysed using IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp. One-way analysis of variance (ANOVA) was performed to determine significant differences due to antioxidant activities of released ascorbyl palmitate by α-amylase from encapsulated maize starches (normal and high amylose maize starch) during pasting and spray drying. The means were separated using the least significant difference (LSD) test. 3. Results and discussion 3.1. Storage stability (Dark/UV light conditions and high-temperature storage) The antioxidant activities of free (unpasted and unsprayed dried) and released ascorbyl palmitate from encapsulated ascorbyl palmitate in maize starches (normal and high amylose maize starch) that were
Fig. 1. Effect of storage condition (dark and 40 °C) for 12 weeks on antioxidant activities of ascorbyl palmitate before and after pasting and spray drying with maize starches (normal and high amylose maize starch) over a period. (30–180 min). AP is Ascorbyl palmitate Keys A is 50 mg AP/g normal maize starch before pasting B is 200 mg AP/g normal maize starch before spray drying C is 200 mg AP/g high amylose maize starch before spray drying D is 50 mg AP/g normal maize starch after pasting E is 200 mg AP/g normal maize starch after spray drying F is 200 mg AP/g high amylose maize starch after spray drying Error bars represent standard deviation
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Fig. 2. Effect of storage condition (UV light and 40 °C) for 12 weeks on antioxidant activities of ascorbyl palmitate before and after pasting and spray drying with maize starches (normal and high amylose maize starch) over a period.(30–180 min). AP is Ascorbyl palmitate Keys A is 50 mg AP/g normal maize starch before pasting B is 200 mg AP/g normal maize starch before spray drying C is 200 mg AP/g high amylose maize starch before spray drying D is 50 mg AP/g normal maize starch after pasting E is 200 mg AP/g normal maize starch after spray drying F is 200 mg AP/g high amylose maize starch after spray drying
degradation of free (before pasting and spray drying) ascorbyl palmitate (Fig. 3A–C) seems to follow the 1 st order kinetic reaction, showing a fast reaction rate. This is typical of oxidation of fat that is usually shows exponential degradation under light conditions (Špiclin et al., 2001). The antioxidant activity of ascorbyl palmitate released from the pasted and spray dried starches with ascorbyl palmitate stored under UV light for 12 weeks did not show a first order decrease. The antioxidant activities of the released ascorbyl palmitate for samples that contained 50 and 200 mg of ascorbyl palmitate in normal maize starch were 10.4 and 38.7 (μmol TE/g) while that of 200 mg ascorbyl palmitate in high amylose maize starch was 36.2 (μmol TE/g) at week zero (Fig. 3). There was no significant difference (P > 0.05) in reduction observed in the antioxidant activities during the storage period of 12 weeks, and this was also similar to those when stored in the dark condition. The stability of ascorbyl palmitate released from the encapsulated sample may be attributed to encapsulation that may have prevented photo-oxidation, and thus no degradation of ascorbyl palmitate. The reduction in antioxidant activities of ascorbyl palmitate stored under UV light observed after the sixth week may be due to oxidative degradation of ascorbyl palmitate to 2, 3-diketogulonic acid has reported by Giuffrida et al. (2007). Oxidative degradation has been reported to be facilitated by UV light, and this consequently speeds up the rate of oxidation of ascorbyl palmitate. In photo-oxidation, UV light is absorbed by ascorbyl palmitate thereby creating an electron-hole pair. Electron-hole pair generates free radicals (RO·) that can undergo secondary reactions to create more free radicals (Kondrakov et al., 2014).
(P > 0.05) in the antioxidant activities of all the samples at the beginning and after the 12th week of storage under dark conditions. The stability of free ascorbyl palmitate stored in dark cupboard at 40 °C observed in this research may be due to the absence of UV light and little amount of oxygen, which cannot cause detectable oxidative degradation of free ascorbyl palmitate. In addition, the ability of ascorbyl palmitate to withstand higher temperature contributed to the stability of free ascorbyl palmitate during storage (Gwo, Flick, Dupuy, Ory, & Baran, 1985). This result was similar to the result of Alborzi, Lim, and Kakuda, (2013) who reported stability of encapsulated folic acid (in mixture of low viscosity sodium alginate pectin and medium viscosity sodium alginate pectin) stored in the dark condition at pH 3 and 25 °C temperature for 41 days. Fig. 2 (supplementary Table 2) shows the antioxidant activities of free (non-encapsulated: before pasting/spray drying) and the released ascorbyl palmitate from encapsulated ascorbyl palmitate in normal and high amylose maize starch stored under UV light at 40 °C. The antioxidant activities of the free ascorbyl palmitate were higher than that of the released ascorbyl palmitate after enzymatic hydrolysis of encapsulated ligand at week zero. The release ascorbyl palmitate from unpasted that contained 50 mg ascorbyl palmitate stored under light condition (UV light) lost its antioxidant activity after 6 weeks of storage. The samples that contained 200 mg of free ascorbyl palmitate in maize starches (normal and high amylose maize starch before spray drying) stored under the same condition (UV light) had negligible scavenging power by the 12th week of storage (0.4 μmol TE/g) compared to a high scavenging power at week zero (60.6 μmol TE/g). The
Fig. 3. DSC thermogram of residues obtained after hydrolysing encapsulated AP in maize starches (normal and high amylose maize starch) with α-amylase enzyme for 180 min. AP = Ascorbyl Palmitate Keys A is control sample (residue obtained from normal maize starch pasted without ascorbyl palmitate) B is residue obtained from enzymatic hydrolysis of 50 mg AP/g normal maize starch pasted C is residue obtained from enzymatic hydrolysis 200 mg AP/g normal maize starch spray dried D is residue obtained from enzymatic hydrolysis 200 mg AP/g high amylose maize starch spray dried
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Encapsulation of ascorbyl palmitate in normal and high amylose maize starch may prevent photo-oxidation reaction of ascorbyl palmitate in starch by preventing the absorption of UV light and preventing the creation of electron-hole pair. This is because ascorbyl palmitate has formed complexes with amylose during pasting and spray drying. The fatty acid moiety of ascorbyl palmitate is trapped inside the amylose helical structure and is not available for interaction with UV light. Bamidele et al. (2017, 2019) reported that the antioxidant activities of the released ascorbyl palmitate are directly proportional to the amount released. The antioxidant activities of released ascorbyl palmitate from encapsulated ascorbyl palmitate during pasting and stored under dark and UV light conditions were 9.4 & 9.5 μmol TE/g. This result was similar to the report of Bamidele et al. (2017) reported that the antioxidant activity of ascorbyl palmitate released from pasted unwashed sample was 9.6 μmol TE/g. The antioxidant activity of released ascorbyl palmitate from unwashed spray dried samples stored under dark and UV light at 40 °C were 39.2 & 35.4 μmol TE/g, and 39.6 & 36.5 μmol TE/g respectively. The results were also similar to Bamidele et al. (2019) who found that the antioxidant activity of released ascorbyl palmitate from encapsulated ascorbyl palmitate was 40.4 μmol TE/g from normal maize starch and 37.4 μmol TE/g from high normal maize starch. This suggests that similar amount of ascorbyl palmitate were released in the current shelf life study compared to those reported by Bamidele et al. (2017, 2019) During incubation time (180 min) with the α-amylase enzyme, there seems to be a limited release of ascorbyl palmitate. It has been reported that amylose-lipid complexes are resistant to α-amylase digestion (Eerlingen & Delcour, 1995). Bound ascorbyl palmitate is expected to be released in the large intestine by microbial fermentation in the large intestine (William et al., 2001). Louis, Scott, Duncan, and Flint, (2007) reported that non-digestible components such as resistance starch that escape digestion by the endogenous enzymes in upper gastrointestinal tract becomes available as substrates in the large intestine for microbial fermentation. The antioxidant activities for week zero of the sample that contained 200 mg ascorbyl palmitate in spray-dried normal and high amylose starch differed despite having the same amount of ascorbyl palmitate. This may be due to more formation of amylose-lipid complexes by high amylose maize starch due to higher content of amylose present in the maize. Ocloo et al. (2016) reported the amylose content of high amylose maize starch (HYLON VII) to be 62%. They reported an increase in second peak viscosity when stearic acid was pasted with high amylose maize. The DSC results of our previous study (Bamidele et al., 2019) also showed higher enthalpy (ΔH) (5.9 J/g) for amyloselipid complexes formed with high amylose maize starch than amyloselipid complexes formed with normal maize starch (3.5 J/g). The higher enthalpy suggests higher amount of complex formed during spray drying of high amylose maize starch with ascorbyl palmitate compared normal maize starch.
Table 1 Endothermic peak value of residues of encapsulated AP in normal and high amylose maize starch after hydrolysis with α-amylase enzyme for 180 min. Samples
To °C
Tp °C
Tc °C
ΔH (J/g)
A B C D
ND 90.3a ± 0.5 91.4b ± 0.3 91.5b ± 0.4
ND 97.7a ± 0.3 98.9b ± 0.4 99.2b ± 0.5
ND 102.1a ± 0.7 109.4b ± 0.9 109.8b ± 1.1
ND 2.2a ± 0.2 4.9b ± 0.3 4.9b ± 0.3
Values within same columns with different letters are significantly different (p < 0.05). ND is not detected, AP- Ascorbyl palmitate. Keys A is control sample (residue obtained from normal maize starch pasted without ascorbyl palmitate). B is residue obtained from enzymatic hydrolysis of 50 mg AP/g normal maize starch pasted. C is residue obtained from enzymatic hydrolysis 200 mg AP/g normal maize starch spray dried. D is residue obtained from enzymatic hydrolysis 200 mg AP/g high amylose maize starch spray dried.
temperature of 99.2 °C and enthalpy of 4.9 J/g. All the residue samples obtained after α-amylase hydrolysis for 180 min of encapsulated ascorbyl palmitate in normal maize starch during pasting and encapsulated ascorbyl palmitate in both normal and high amylose maize starch during spray drying, showed type I amyloselipid complexes. Amylose-lipid complexes is formed due to hydrophobic interaction within the helical cavity of amylose and hydrocarbon chain of lipid compounds (Immel & Lichtenthaler, 2000). The amylose chain shows a characteristic turn (natural twist) giving a helical adaptation with six anhydroglucose unit per turn. When the fatty acid ester (ascorbyl palmitate) was added to the system during pasting or spray drying, the hydrocarbon chain of palmitate part of ascorbyl palmitate can enter hydrophobic cavity to form amylose-ascorbyl palmitate complexes. Type I amylose lipid complexes are formed at 60 °C and have melting temperatures of about 98 °C (Biliaderis & Galloway, 1989). Other authors also found the melting of type I amylose lipidcomplexes at 100 °C (Biliaderis, Page, Slade, & Sirett, 1985; Biliaderis & Galloway, 1989). The melting endotherms at 98–99? C (Fig. 3 and Table 1) thus showed the presence of type I amylose-lipids complexes in the residues obtained after enzymatic hydrolysis of starch used to encapsulate ascorbyl palmitate. Amylose-lipid complexes type II was formed when normal maize starch was pasted with ascorbyl palmitate (Bamidele et al., 2017). This was attributed to long pasting time and has been reported by Wokadala et al. (2012). Amylose-lipid complexes type I was observed in the residue obtained after hydrolysing the pasted sample containing 50 mg AP/g normal maize starch and spray dried samples containing 200 mg AP/g in normal and high amylose maize starch. Amylose-lipid complexes type I observed in the residues may be attributed to the effect of the α-amylase enzyme that has converted type II amylose-lipid complexes to type I amylose-lipid complexes. This may be possible because of the prolonged incubation time (180 min) of amylose-lipid complexes type II with the α-amylase enzyme, which attacked the exposed α-1-4 glycosidic bond present in the amorphous region of type II amyloselipid complexes. Obiro, Sinha Ray, and Emmambux, (2012) and Gelders, Duyck, Goesaert, and Delcour, (2005) showed the postulated diagram of V-amylose type II complex morphology. They suggested that type II amylose-lipid complexes occurred as semi-crystalline structure linked by amorphous region. The amylose lipid complexes as type II are rod like structures parallel to each other and linked at the end of the rod by amorphous region to form a higher molecular order structure with higher melting point. It can be postulated that the bonds (α-1-4 glycosidic bond) of the amylose molecule is exposed in the amorphous region, thus they are hydrolysed by the enzyme (α-amylase) during incubation to disturb the higher molecular order structure, thereby
3.2. Differential scanning calorimetry of residue from digested samples Fig. 3 and Table 1 show the results of differential scanning calorimetry of the residues obtained after enzymatic hydrolysis of pasted and spray dried starches with ascorbyl palmitate. All the residues obtained from the hydrolysed samples (50 mg AP/g starch, pasted, 200 mg AP/g normal maize starch spray dried and 200 mg AP/ g high amylose maize starch spray dried) showed one endothermic peak except the control sample (no peak) without ascorbyl palmitate. The residue obtained from a sample that contained 50 mg ascorbyl palmitate pasted with normal maize starch has one endothermic peak with a peak temperature of 97.7 °C and enthalpy of 2.2 J/g. The residue obtained from a sample that contained 200 mg ascorbyl palmitate spray dried with normal maize starch has the peak temperature of 98.9 °C and enthalpy of 4.9 J/g. The residue obtained from spray-dried sample containing 200 mg ascorbyl palmitate in high amylose maize starch has the peak 221
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Fig. 4. CLSM images of washed (pasted and spray dried) samples, and residues obtained from digested encapsulated AP in starches (native maize starch and high amylose maize starch) using α-amylase enzyme. Each bar- 20X, Y is starch matrix and X is ascorbyl palmitate AP- Ascorbyl palmitate NMS – Normal maize starch HAMS – High amylose maize starch
UV light conditions at 40 °C, but free ascorbyl palmitate (Non-encapsulated) is degraded under UV light in respect to their antioxidant activities. The rate of starch hydrolysis of encapsulated ascorbyl palmitate in maize starches (normal maize starch and high amylose maize starch) is partial and the residue from the entire hydrolysed sample still contain some ascorbyl palmitate.
leading to type I amylose-lipid complexes observed in the residues of the hydrolysed samples. 3.3. Confocal laser scanning microscopy The confocal laser scanning micrograph (CLSM) of the samples (200 mg ascorbyl palmitate in normal maize starch and 200 mg ascorbyl palmitate in high amylose starch) before enzymatic hydrolysis fluorescence while after enzymatic hydrolysis showed no fluorescence (Fig. 4). Fluorescence observed before enzymatic hydrolysis may be due to the interaction between ascorbyl palmitate that was trapped in the starch matrix and Nile Red dye used to stain the sample. The absence of fluorescence from the same sample (residue of 200 mg ascorbyl palmitate in normal and high amylose starch) after enzymatic hydrolysis may be attributed to unavailability of ascorbyl palmitate to interact with Nile Red dye used to stain the sample. Nile red interacts with the free fatty acid component of ascorbyl palmitate. However, this was not the case in this study for the non-hydrolysed residues as the fatty acid component of ascorbyl palmitate was probably inside the amylose helical structure. In other studies, Bamidele et al. (2019) reported fluorescence when Nile red dye was added to a mixture maize starch and ascorbyl palmitate before spray drying. This was due to availability of free ascorbyl palmitate to Nile Red dye after spray drying and the free ascorbyl palmitate was washed off, there was no fluorescence of ascorbyl palmitate because of the complexation of ascorbyl palmitate with amylose to form amylose-ascorbyl palmitate complexes or the ascorbyl palmitate was physically entrapped. The DSC and CLSM results show that the residue obtained from the hydrolysed encapsulated ascorbyl palmitate, which is inferred to reach the large intestine after escaping the upper gastrointestinal tract, contains ascorbyl palmitate. This could provide potential health benefit due to the antioxidant properties of ascorbyl palmitate. The report of Williams, Verstegen, Tamminga, and 2001 reported that fermentation of resistant starch (e.g. amylose-lipid complexes) in the large intestine by the microflora is possible since some of the undigested dietary components will move from the small intestine into the large intestine.
Acknowledgements The authors would like to acknowledge the National Research Foundation (NRF) and DST/NRF Centre of Excellence in Food Security and University of Pretoria for funding the research work. Appendix A. Supplementary data Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.carbpol.2019.04.022. References Alborzi, S., Lim, L. T., & Kakuda, Y. (2013). Encapsulation of folic acid and its stability in sodium alginate-pectin-poly (ethylene oxide) electrospun fibres. Journal of Microencapsulation, 30(1), 64–71. Bakowska-Barczak, A. M., & Kolodziejczyk, P. P. (2011). Black currant polyphenols: Their storage stability and microencapsulation. Industrial Crops and Products, 34(2), 1301–1309. Bamidele, O. P., Duodu, K. G., & Emmambux, M. N. (2017). Encapsulation and antioxidant activity of ascorbyl palmitate with maize starch during pasting. Carbohydrate Polymers, 166, 202–208. Bamidele, O. P., Duodu, K. G., & Emmambux, M. N. (2019). Encapsulation and antioxidant activity of ascorbyl palmitate with normal and high amylose maize starch by spray drying. Food Hydrocolloids, 86, 124–133. Biliaderis, C. G., & Galloway, G. (1989). Crystallization behavior of amylose-V complexes: Structure-property relationships. Carbohydrate Research, 189, 31–48. Biliaderis, C. G., Page, C. M., Slade, L., & Sirett, R. R. (1985). Thermal behavior of amylose-lipid complexes. Carbohydrate Polymers, 5(5), 367–389. Carstensen, J. T. (2000). Oxidation in solution. In J. T. Carstensen, & C. T. Rhodes (Eds.). Drug stability, principles, and practices (pp. 113–131). New York: Dekker. Case, S. E., Capitani, T., Whaley, J. K., Shi, Y. C., Trzasko, P., Jeffcoat, R., et al. (1998). Physical properties and gelation behavior of a low-amylopectin maize starch and other high-amylose maize starches. Journal of Cereal Science, 27(3), 301–314. 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, 4212–4218. Dima, Ş., Dima, C., & Iordăchescu, G. (2015). Encapsulation of functional lipophilic food and drug biocomponents. Food Engineering Reviews, 7, 417–438. Dries, D. M., Knaepen, L., Goderis, B., & Delcour, J. A. (2017). Encapsulation of the antioxidant ascorbyl palmitate in V-type granular cold-water swelling starch affects the properties of both. Carbohydrate Polymers, 165, 402–409.
4. Conclusions Encapsulated ascorbyl palmitate by formation of amylose lipid inclusion complexes makes the ligand stable when stored in the dark and 222
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of encapsulated sour cherry phenolic compounds prepared from micro-and nanosuspensions. Food and Bioprocess Technology, 7(1), 204–211. Munin, A., & Edwards-Lévy, F. (2011). Encapsulation of natural polyphenolic compounds; a review. Pharmaceutics, 3(4), 793–829. Obiro, W. C., Sinha Ray, S., & Emmambux, M. N. (2012). V-amylose structural characteristics, methods of preparation, significance, and potential applications. Food Reviews International, 28, 412–438. Ocloo, F. C., Minnaar, A., & Emmambux, N. M. (2016). Effects of stearic acid and gamma irradiation, alone and in combination, on pasting properties of high amylose maize starch. Food Chemistry, 190, 12–19. Saénz, C., Tapia, S., Chávez, J., & Robert, P. (2009). Microencapsulation by spray drying of bioactive compounds from cactus pear (Opuntia ficus-indica). Food Chemistry, 114(2), 616–622. Singh, S., & Bakshi, M. (2000). Stress test to determine the inherent stability of drugs. Pharmaceutical Technology, 4, 1–14. Špiclin, P., Gašperlin, M., & Kmetec, V. (2001). Stability of ascorbyl palmitate in topical microemulsions. International Journal of Pharmaceutics, 222, 271–279. Williams, B. A., Verstegen, M. W., & Tamminga, S. (2001). Fermentation in the large intestine of single-stomached animals and its relationship to animal health. Nutrition Research Reviews, 14(2), 207–228. Wokadala, O. C., Ray, S. S., & Emmambux, M. N. (2012). The occurrence of amylose-lipid complexes in teff and maize starch biphasic pastes. Carbohydrate Polymers, 90, 616–622. Yuan, J. P., & Chen, F. (1998). Degradation of ascorbic acid in aqueous solution. Journal of Agricultural and Food Chemistry, 46(12), 5078–5082. Zhou, M., Li, X., Li, Y., Yao, Q. E., Ming, Y., Li, Z., et al. (2017). Ascorbyl palmitateincorporated paclitaxel-loaded composite nanoparticles for synergistic anti-tumoral therapy. Drug Delivery, 24(1), 1230–1242.
Eerlingen, R. C., & Delcour, J. A. (1995). Formation, analysis, structure, and properties of type III enzyme resistant starch. Journal of Cereal Science, 22, 129–138. Gelders, G. G., Duyck, J. P., Goesaert, H., & Delcour, J. A. (2005). Enzyme and acid resistance of amylose-lipid complexes differing in amylose chain length, lipid and complexation temperature. Carbohydrate Polymers, 60, 379–389. Giuffrida, F., Destaillats, F., Egart, M. H., Hug, B., Golay, P. A., Skibsted, L. H., et al. (2007). Activity and thermal stability of antioxidants by differential scanning calorimetry and electron spin resonance spectroscopy. Food Chemistry, 101, 1108–1114. Gwo, Y. Y., Flick, G. J., Jr., Dupuy, H. P., Ory, R. L., & Baran, W. L. (1985). Effect of ascorbyl palmitate on the quality of frying fats for deep frying operations. Journal of the American Oil Chemists’ Society, 62, 1666–1671. Immel, S., & Lichtenthaler, F. W. (2000). The hydrophobic topographies of amylose and its blue iodine complex. Starch-Stärke, 52(1), 1–8. Jafari, S. M., Assadpoor, E., He, Y., & Bhandari, B. (2008). Encapsulation efficiency of food flavours and oils during spray drying. Drying Technology, 26, 816–835. Kondrakov, A. O., Ignatev, A. N., Frimmel, F. H., Bräse, S., Horn, H., & Revelsky, A. I. (2014). Formation of genotoxic quinones during bisphenol A degradation by TiO 2 photocatalysis and UV photolysis: A comparative study. Applied Catalysis B, Environmental, 160, 106–114. Kong, L., & Ziegler, G. R. (2014). Molecular encapsulation of ascorbyl palmitate in preformed V-type starch and amylose. Carbohydrate Polymers, 111, 256–263. Lalush, I., Bar, H., Zakaria, I., Eichler, S., & Shimoni, E. (2005). Utilization of amylose−Lipid complexes as molecular nanocapsules for conjugated linoleic acid. Biomacromolecules, 6, 121–130. Louis, P., Scott, K. P., Duncan, S. H., & Flint, H. J. (2007). Understanding the effects of diet on bacterial metabolism in the large intestine. Journal of Applied Microbiology, 102, 1197–1208. Luca, A., Cilek, B., Hasirci, V., Sahin, S., & Sumnu, G. (2014). Storage and baking stability
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