Pickering emulsifiers based on hydrophobically modified small granular starches Part II - Effects of modification on emulsifying capacity

Spatially selective catalysis of OSA starch for preparation of Pickering emulsions with high emulsification properties

The traditional strategies of chemical catalysis and biocatalysis for producing octenyl succinic anhydride modified starch can only randomly graft hydrophobic groups on the surface of starch, resulting in unsatisfactory emulsification performance. In this work, a lipase-inorganic hybrid catalytic system with multi-scale flower like structure is designed and applied to spatially selective catalytic preparation of ocenyl succinic anhydride modified starch. With the appropriate floral morphology and petal density, lipases distributed in the "flower center" can selectively catalyze the grafting of hydrophobic groups in a spatial manner, the hydrophobic groups are concentrated on one side of starch particles. The obtaining OSA starch exhibits excellent emulsifying property, and the pickering emulsion has good protective effect on the embedded curcumin. This work provides a direction for the development of high-performance starch-based emulsifiers for the food and pharmaceutical industries, which is of great significance for improving the preparation and emulsification theory research of modified starch.

Effects of synchronous intermissive multi-ultrasound and esterification dual modification on functionalities of starch and its emulsion stabilization ability

Dodecenylsuccinic anhydride (DDSA) has been widely used to obtain amphiphilic starches. In this study, we investigated the functionalities of synchronous intermissive multi-ultrasound-assisted esterified starch. Compared to native starch (NS), it was deduced that multi-ultrasound-modified starch (US), esterified starch (ES), and multi-ultrasound-assisted esterified starch (UES) exhibited increased viscosities but reduced gelatinization temperatures and thermal stabilities. The viscoelastic moduli, retrogradation behaviors and hydrophobicity of the ES and UES species significantly altered. Moreover, the results of structural characterization suggested that esterification reduced the molecular weight and structural order of starch, whereas the intermissive ultrasonication treatment did not aggravate the structural disruption of ES. Additionally, compared with NS and US, the emulsification abilities of the ES and UES specimens were improved, leading to the desirable effect of stabilizing astaxanthin. Overall, this study provides a method for preparing amphiphilic starch, which can be exploited as a potential emulsifier and emulsion stabilizer for bioactive compounds.

Effect of ultrasonic power on delivery of quercetin in emulsions stabilized using octenyl succinic anhydride (OSA) modified broken japonica rice starch

In this study, emulsions stabilized by octenyl succinic anhydride-modified broken japonica rice starch (OSA-BJRS) were prepared at different ultrasonic power intensities for the delivery, controlled release, and improved bioavailability of quercetin. The OSA-BJRS emulsions ultrasonicated at 400 W exhibited the highest encapsulation efficiency (89.37 %) and loading efficiency (58.34 %) of quercetin, the smallest volume-average droplet diameter (0.51 μm) and polydispersity index (0.19), the highest absolute value of the ζ-potential (26.73 mV), and the highest apparent viscosity and viscoelasticity. The oxidation stability, storage stability, thermal stability, and salt ion stability of the emulsions were also notably improved by the ultrasonication treatment. In addition, the results of the simulated in vitro digestion demonstrated that the ultrasonicated OSA-BJRS emulsions had an enhanced quercetin delivery performance and could stably transport quercetin to the small intestine for digestion. The OSA-BJRS emulsion ultrasonicated at 400 W exhibited the highest cumulative release rate (95.91 %) and the highest bioavailability (30.48 %) of quercetin. This suggests that OSA-BJRS emulsions prepared by ultrasonication can be considered effective delivery systems for hydrophobic functional components.

Functionality differences between esterified and pregelatinized esterified starches simultaneously prepared by octenyl succinic anhydride modification and its application in dough

Octenyl succinic anhydride (OSA)-modified starches have gained widespread interest, but the modification can produce two starches with different states ignored. Herein, the two types of starches, esterified starch (ES) and pregelatinized esterified starch (PES), prepared by OSA modification were separated, and their structural and functional characteristics were comprehensively explored. Results showed that compared with native starch (NS), ES and PES exhibited high water-holding capacity, solubility, and swelling power and significantly decreased pasting temperature and thermal stability. Dynamic rheological tests illustrated that OSA modification changed the rheological behavior of starches. Fourier transform infrared spectroscopy confirmed that PES with higher degree of substitution showed more obvious ester carbonyl and carboxylate groups than ES. Laser confocal micro-Raman spectroscopy revealed that the short-range molecular order of ES, especially PES, decreased after modification. X-ray diffraction indicated that OSA modification disrupted the crystalline structure of starch, and that more amylose-lipid complex was formed in PES. Scanning electron microscopy showed that OSA modification eroded starchs surface and reduced its smoothness, and significantly disrupted PES integrity. ES and PES could be developed as food additives for retrogradation inhibition of dough. These results provide new insights into OSA modification and expand its functional application in foods.

Preparation and Physico-Chemical Characterization of OSA-Modified Starches from Different Botanical Origins and Study on the Properties of Pickering Emulsions Stabilized by These Starches

Native starch (NS) from different botanical origins (native rice/tapioca/oat starch, NRS/NTS/NOS) were hydrophobically modified by octenyl succinic anhydride (OSA), and the octenyl succinic (OS) groups were successfully introduced in the starch molecules which obtained OS-starch (OSRS, OSTS and OSOS) with different levels of modification (0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%) and degree of substitution (DS). The structural properties of the OS-starch, such as granule size, crystal, wettability and morphology were studied, and the OS-starch was used as particulate stabilizers to produce oil-in-water (O/W) Pickering emulsions. The emulsion index, droplet size distribution and microstructures of Pickering emulsions produced by different OS-starches were compared. OSA modification had almost no effect on the morphology or crystal structure types of three kinds of NS and OS-starch but markedly increased the contact angle and particle size distribution of OSRS, OSTS and OSOS. Esterification reaction of OSA and starch mainly occurred in amorphous regions of starch, and the OSA significantly improved the emulsifying capacity of OSRS, OSTS and OSOS granules and thus stabilized emulsions formed at higher levels (2.5% and 3.0%) of modification of OS-Starch exhibited better stability; the ability of OS-starch to stabilize Pickering emulsion was 3.0% OSRS > 3.0% OSOS > 3.0% OSTS, respectively. Observation and structural properties analysis of OS-starch granules and Pickering emulsion droplets showed that the number and thickness of the starch granules on the oil-water interface of the emulsion droplets increased with improvement of the OSA modification level, and an aggregation state was formed between the OS-starch granules, which was also enhanced with the OSA modification levels. These were all necessary for the Pickering emulsion stabilized by starch granules to remain in a steady state.

Advances in isolation, characterization, modification, and application of Chenopodium starch: A comprehensive review

The Chenopodium genus includes >250 species, among which only quinoa, pigweed, djulis, and kaniwa have been explored for starches. Chenopodium is a non-conventional and rich source of starch, which has been found effective in producing different classes of food. Chenopodium starches are characterized by their smaller granule size (0.4-3.5 μm), higher swelling index, shorter/lower gelatinization regions/temperature, good emulsifying properties, and high digestibility, making them suitable for food applications. However, most of the investigations into Chenopodium starches are in the primary stages (isolation, modification, and characterization), except for quinoa. This review comprehensively explores the major developments in Chenopodium starch research, emphasizing isolation, structural composition, functionality, hydrolysis, modification, and application. A critical analysis of the trends, limitations, and scope of these starches for novel food applications has also been provided to promote further scientific advancement in the field.

Enzymatically modified quinoa starch-based Pickering emulsion: Effect of enzymolysis and emulsifying conditions

Both the effects of enzymolysis condition on the microstructures and emulsifying property of enzymatic modified quinoa starch (EMQS) and the effects of emulsion formulation on the EMQS based emulsions were investigated. The emulsifying capacity (EC) and stability (ES) of EMQS were positive correlated with enzyme amount (0-2.4 % w/w_starch). The particle sizes of EMQS decreased and its hydrophobicity increased with increasing enzyme amount (0-2.4 % w/w_starch), which were the main reasons for the increasing emulsifying performance of EMQS. With the increasing starch concentration, the EC of the EMQS increased, the oil droplet size of the emulsion decreased. With the oil/water ratios ranging from 1:9 to 6:4, the emulsification index (EI) and oil droplet size of the emulsion increased. EMQS based emulsion had a relatively good stability in the pH range of 2-10. This study lays the foundation for the application of EMQS as a stable clean-label Pickering emulsifier.

The Fabrication and Characterization of Pickering Emulsion Gels Stabilized by Sorghum Flour

Pickering emulsion gels have potential application as solid fat substitutes and nutraceutical carriers in foods, but a safe and easily available food-derived particle emulsifier is the bottleneck that limits their practical application. In this study, the function of sorghum flour as a particle emulsifier to stabilize the oil-in-water (O/W) Pickering emulsion gels with medium chain triglycerides (MCT) in the oil phase was introduced. Sorghum flour had suitable size distribution (median diameter, 21.47 μm) and wettability (contact angle, 38°) and could reduce the interfacial tension between MCT and water. The oil phase volume fraction (φ) and the addition amount of sorghum flour (c) had significant effects on the formation of Pickering emulsion gels. When c ≥ 5%, Pickering emulsion gels with φ = 70% could be obtained. Microstructure analysis indicated that sorghum flour not only played an emulsifying role at the O/W interface but also prevented oil droplets from coalescing through its viscous effect in the aqueous phase. With increases in c, the droplet size of the emulsion gel decreased, its mechanical properties gradually strengthened, and its protective effect on β-carotene against UV irradiation also improved.

Whey Protein Isolate Nanofibers Prepared by Subcritical Water Stabilized High Internal Phase Pickering Emulsion to Deliver Curcumin

This study aimed to design a Pickering emulsion (PE) stabilized by whey protein isolate nanofibers (WPINs) prepared with subcritical water (SW) to encapsulate and prevent curcumin (Cur) degradation. Cur-loaded WPINs–SW stabilized PE (WPINs–SW–PE) and hydrothermally prepared WPINs stabilized PE (WPINs–H–PE) were characterized using the particle size, zeta potential, Congo Red, CD, and TEM. The results indicated that WPINs–SW–PE and WPINs–H–PE showed regular spherical shapes with average lengths of 26.88 ± 1.11 μm and 175.99 ± 2.31 μm, and zeta potential values were −38.00 ± 1.00 mV and −34.60 ± 2.03 mV, respectively. The encapsulation efficiencies of WPINs–SW–PE and WPINs–H–PE for Cur were 96.72 ± 1.05% and 94.07 ± 2.35%. The bio-accessibility of Cur of WPINs–SW–PE and WPINs–H–PE were 57.52 ± 1.24% and 21.94 ± 2.09%. In addition, WPINs–SW–PE had a better loading effect and antioxidant activities compared with WPINs–H–PE. SW could be a potential processing method to prepare a PE, laying the foundation for the subsequent production of functional foods.

Ferulic acid loaded pickering emulsions stabilized by resistant starch nanoparticles using ultrasonication: Characterization, in vitro release and nutraceutical potential

The use of starch based nanoparticles have gained momentum in stabilizing pickering emulsions for it's numerous advantages. In present study resistant starch (RS) was isolated from lotus stem using enzymatic digestion and subjected to nanoprecipitation and ultrasonication to yield resistant starch nanoparticles (RSN). RSN of varying concentrations (2%, 10% and 20%) were used to stabilize the flax seed-oil water mixture to form pickering emulsions. The emulsions were used to nanoencapsulate ferulic acid (FA) - a well known bioactive via ultrasonication. The emulsions were lyophilized to form FA loaded lyophilized pickering emulsion (FA-LPE). The FA-LPE (2%, 10 % and 20%) were characterized using dynamic light scattering (DLS), light microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and attenuated total reflectance fourier transform infra-spectroscopy (ATR-FTIR). AFM showed FA-LPE as spherical droplets embedded in the matrix with maximum peak height of 8.47 nm and maximum pit height of 1.69 nm. SEM presented FA-LPE as an irregular and continuous surface having multiple folds and holes. The ATR-FTIR spectra of all the samples displayed peaks of C = C aromatic rings of FA at 1600 cm^-1 and 1439 cm^-1, signifying successful encapsulation. In vitro release assay displayed more controlled release of FA from FA-LPE (20%). Bioactivity of FA-LPE was evaluated in terms of anti-cancer, anti-diabetic, angiotensin converting enzyme (ACE) inhibition and prevention against oxidative damage under simulated gastro-intestinal conditions (SGID). The bioactivity of FA-LPE (20%) was significantly higher than FA-LPE (2%) and FA-LPE (10%). Key findings reveal that pickering emulsions can prevent FA under harsh SGID conditions and provide an approach to facilitate the design of pickering emulsions with high stability for nutraceutical delivery in food and supplement products.

Resveratrol loaded Pickering emulsions stabilized by OSA modified rice starch granules

Resveratrol is a photosensitive, bioactive molecule which has received increasing research interest during the past decade for its antioxidant properties. However, it has low solubility in water or common triglyceride oils. Resveratrol solubilization in oil can only be achieved in essential oils, such as flavour oils, but the stability of emulsions produced with this type of oils is low as they are prone to creaming phenomena and Oswald ripening. In this study, resveratrol was first dissolved in orange oil which was mixed into a medium-chain triglyceride (Miglyol) at different ratios and used as the internal phase of oil-in-water emulsions (O/W). The emulsions were stabilized by octenyl succinic anhydride (OSA) modified rice starch granules using two different ratios of starch particle:oil to study the influence of interfacial coverage on the final emulsion droplet size and emulsion stability. The results of this study indicated that stable Pickering emulsions could be prepared using OSA-modified rice starch granules even at partial coverage conditions. Emulsions prepared at an oil fraction of 0.5 using 30% v/v mixture of orange oil in Miglyol as the dispersed phase seemed to be an appropriate resveratrol carrier system, obtaining encapsulation efficiency values close to 90% which results in emulsions with a resveratrol concentration of 8.45 mg/L. Hence, the emulsions prepared are suitable for food fortification applications.

Evaluation of Changes in Protein Quality of High-Pressure Treated Aqueous Aquafaba

Chickpea cooking water (CCW), known as aquafaba, has potential as a replacement for egg whites due to its emulsion and foaming properties which come from the proteins and starch that leach out from chickpeas into the cooking water. High pressure (HP) processing has the ability to modify the functional characteristics of proteins. It is hypothesized that HP processing could favorably affect the functional properties of CCW proteins by influencing their structure. The objective of this study to evaluate the effect of HP treatment on the associated secondary structure, emulsion properties and thermal characteristics of CCW proteins. A central composite rotatable design is used with pressure level (227-573 MPa) and treatment time (6-24 min) as HP variables, and concentration of freeze dried CCW aquafaba powder (11-29%) as product variable, and compared to untreated CCW powder. HP improves aquafaba emulsion properties compared to control sample. HP reduces protein aggregates by 33.3%, while β-sheets decreases by 4.2-87.6% in which both correlated to increasing protein digestibility. α-helices drops by 50%. It affects the intensity of some HP treated samples, but not the trend of bands in most of them. HP treatment decreases Td and enthalpy because of increasing the degree of denaturation.

Structure and physicochemical properties of amphiphilic agar modified with octenyl succinic anhydride

A novel amphiphilic agar with high transparency and freeze-thaw stability was prepared using octenyl succinic anhydride (OSA). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed that the hydrophobic OS groups were successfully introduced in OSA-modified agar (OSAR) backbone. The OSAR showed higher emulsion stability and oil loading capacity than the native agar (NA). Compared with gel transparency (47.1 %), syneresis (42.1 %) of NA, OSAR exhibited high gel transparency (80 %) and low syneresis (3.3 %) when the degree of substitution (DS) was 0.06 and 0.12, respectively. Meanwhile, the OSAR showed a decreased interface tension and average molecular weight after modification. Thermogravimetric analysis indicated the thermal stability of OSAR was decreased, while texture profile analysis showed the springiness of the OSAR gel was enhanced. Dynamic rheology measurements revealed the OSAR with low gel strength displayed more liquid-like properties. Moreover, the OSAR exhibited lower turbidity and melting temperatures than the NA.

Starch nanocrystals as the particle emulsifier to stabilize caprylic/capric triglycerides-in-water emulsions

Starch nanocrystals (SNCs) grafted with octenyl succinic anhydride (OSA) were used to stabilize caprylic/capric triglycerides (GTCC)-in-water emulsions. The morphology and viscoelasticity of emulsions were studied in terms of particle loadings and degrees of substitution (DSs). It is found that the emulsifying capacities of SNCs increase with increased DSs. Both the pristine SNC and modified ones can be well used to stabilize emulsions, whereas the emulsification follows different mechanisms. The platelet-like structure of SNCs, together with its improved amphiphilicity after surface treatments, are important to the formation and evolution of droplet clusters. The deformation and relaxation of those clusters result in weak flow overshoots and strong thixotropy in different shear flow fields, which favor storage and applications of GTCC-in-water emulsions as hydrocolloids. The mechanisms were then discussed in terms of rigidity of SNC and relaxations of clusters. This work proposes a promising application of SNC in food and cosmetic industries.

Chitin Pickering Emulsion for Oil Inclusion in Composite Films

A film containing a stable and well-dispersed hydrophobic phase in a surfactant-free bio-based hydrophilic matrix is proposed. In this study, an aqueous suspension of rod-like chitin nanocrystals (ChiNCs), mixed with paraffin oil, form an oil-in-water Pickering emulsion with a droplet diameter of 3 μm. These emulsions mixed with a 5 wt% starch solution formed homogeneous composite films by solvent casting. Various amounts of emulsion were incorporated, leading to self-supported films with a volume of oil as high as 45 vol%, with less than 1% of ChiNCs. This model inclusion system leads to droplets homogeneously dispersed throughout the composite films, as revealed by microscopy (SEM and CLSM) with mechanical properties controlled by the matrix. Finally, the droplets were easily released from the matrix by enzymatic hydrolysis. This easy-to-implement transparent film proved to be a good candidate when it is desirable to disperse a poor water-soluble component in a hydrophilic edible matrix.

Starch granule stabilized Pickering emulsions: an 8-year stability study

BACKGROUND

Pickering emulsions are known to have advantages over conventional emulsions, in particular, improved and long-term stability against coalescence. This research is an eight-year stability investigation of oil-in-water Pickering emulsions stabilized by quinoa starch granules modified by octenyl succinic anhydride (OSA). Two different concentrations of starch (i.e. 200 and 600 mg mL^-1 based on oil) were used at oil fraction (ϕ) of 0.1. The emulsions were prepared using a high-pressure homogenizer. The emulsions were stored in a refrigerator (at 6 °C) and evaluated using particle size analyzer over the storage period and light microscopy at the end of the storage period.

RESULTS

Starch granule stabilized Pickering emulsions produced by a high-pressure homogenizer displayed remarkable storage stability over the eight years with no indication of coalescence. In addition, the results showed that increasing the concentration of starch granules resulted in a decrease in droplet sizes. The sizes measured by the particle size analyzer showed a decline over the storage period which was due to dissociation of some networks of aggregated droplets that, in addition to representing smaller droplet sizes, resulted in the release of free and unbound starch entrapped in these networks.

CONCLUSIONS

This study showed that Pickering emulsions produced by OSA modified starch granules from quinoa can be used in practical applications for the development of highly stable formulations when prolonged storage is required. © 2020 Society of Chemical Industry.

Starch nanoparticles modified with styrene oxide and their use as Pickering stabilizers

Starch nanoparticles (SNP) were modified with styrene oxide (STO) and successfully used as Pickering stabilizers in miniemulsion and emulsion polymerization.

Ultra-stable Pickering emulsion stabilized by a natural particle bilayer

An all-natural Pickering emulsion with a Janus interface of particle bilayer is prepared, which has unprecedented stability.