Effect of amyloglucosidase hydrolysis on the multi-scale supramolecular structure of corn starch

Differential impacts of porous starch versus its octenyl succinic anhydride-modified counterpart on naringin encapsulation, solubilization, and in vitro release

The aim of this work was to evaluate the potentials of porous starch (PS) and its octenyl succinic anhydride modified product (OSAPS) as efficient carriers for loading naringin (NA), focusing on encapsulation efficiency (EE, the percentage of adsorbed naringin relative to its initial amount), drug loading (DL, the percentage of naringin in the complex), structural alterations, solubilization and in vitro release of NA using unmodified starch (UMS) and NA as controls. Both the pore diameter and SBET value of PS decreased after esterification with OSA, and a thinner strip-shaped NA (∼145 nm) was observed in the OSAPS-NA complex and (∼150 nm) in the PS-NA complex. OSAPS exhibited reduced short-range ordered structure, as indicated by a lower R1047/1022 (0.73) compared to PS (0.77). Meanwhile, lowest crystallinity (12.81 %) of NA was found in OSAPS-NA. OSAPS-NA exhibited higher EE and DL for NA than PS-NA and a significant increase in NA saturated solubility in deionized water (by 11.63-fold) and simulated digestive fluids (by 24.95-fold) compared to raw NA. OSAPS contained higher proportions of slowly digestible starch and exhibited a lower digestion rate compared to PS, resulting in a longer time for NA release from its complex during the digestion.

Based on proteomics probing into the deterioration mechanism of pork batter gel caused by different cooking temperatures

The purpose of this experiment was to explore the influence of different cooking temperatures on the deterioration characteristics of pork batter gel by using proteomics, gel electrophoresis, size and chemical bond of aggregates. The results showed that the protein molecules of the pork batter gel was degraded during heating cooking and the protein aggregates were composed of many degraded protein fragments; compared with the control group 75 °C (0 min), the significant degradation of cytoskeleton showed at 110 °C (30 min) and 121 °C (30 min) and the significant degradation of myosin complexonly appeared at 121 °C (30 min). As the heating temperature points increased, compared with the control group 75 °C (0 min), the different temperatures could promote the separation of metal ions with proteins especially at 110 °C (30 min) and 121 °C (30 min), which could ultimately influence quality of pork batter gel by the size of particle. As the increase of heating temperature points, the recombination of aggregates composed of different proteins was not conducive to the retention of capillary water, which reduced the texture of pork batter gel. This research provided theoretical support for improving the process property of the meat products.

Porous corn starch granules as effective host matrices for encapsulation and sustained release of curcumin and resveratrol

Type 2 Diabetes Mellitus (T2DM) is a carbohydrate-rich diet-regulated ailment with carbohydrates digested and absorbed rapidly. Hence, modulating carbohydrate digestion is warranted; to this end, polyphenols from plant sources are handy. However, polyphenols' instability and low bioavailability limit their wholesome use, and thus, encapsulating them into an inexpensive and suitable wall material would be the best strategy. Herein, the potential of porous starch granules is demonstrated. Curcumin and resveratrol were chosen as the test polyphenols due to their proven health benefits, and porous corn starch granules were chosen as the wall material. Porous corn starch granules were prepared through enzymatic modification with 11, 22, and 33 units of amyloglucosidase at three reaction times of 2, 4, and 6 h. The polyphenols were loaded at 100, 200, and 500 mg concentrations in 1 g of starch for 21 days and were characterized through Scanning Electron Microscope (SEM) and Fourier Transform Infrared spectroscopy (FTIR) analyses. The encapsulation efficiency was determined, the rate of starch digestion was calculated through the Englyst test, and polyphenols' in vitro release behavior in gastric and intestinal fluids was measured. Results suggest that 33 enzyme units for a 2 h reaction time were optimal for forming spherical-oval pores on corn starch granules with the maximum encapsulation efficiency of 80.16 % and 88.33 % for curcumin and resveratrol, respectively. The FTIR results suggest the entrapment of polyphenols inside the starch matrix. The inclusion significantly reduced starch digestion and increased the percentage of resistant starch up to 41.11 % and 66.36 % with curcumin and resveratrol, respectively. The in vitro release behavior demonstrated good stability in the simulated gastric fluids and sustained release in simulated intestinal fluids. The encapsulated polyphenols showed a complex Fickian type of diffusion mechanism. Overall, the results suggest that porous corn starch granules could be a potential delivery system for curcumin and resveratrol and will aid in developing novel functional foods to address the T2DM concerns.

Comparison of anti-allergic activities of different types of lotus seed resistant starch in OVA-induced mouse model

Currently, evidence from observational studies suggests dietary fiber intake may be associated with decreased risk of food allergy. As a type of dietary fiber, resistant starch was also widely reported to possess anti-allergic properties. However, there is a relative paucity of studies assessing the influence of resistant starch types on their anti-allergic activity and its possible underlying mechanisms. In the current study, the anti-allergic effects of RS3-type (retrograded starch), RS4-type (chemically modified starch, cross-bonded), and RS5-type (starch-palmitic acid complex) of lotus seed resistant starch were evaluated in the OVA (100 mg/kg)-induced food allergic mice model. The results showed that oral administration of RS3 or RS4 lotus seed resistant starch (0.3 g/100 g b.w.) for 25 days significantly improved adverse symptoms of food allergy such as weight loss, increases in allergy symptom score and diarrhea rate; with significant reduction of serum specific antibody IgE, TNF-α, IL-4 levels and improved Th1/Th2 balance being observed. The mechanism may involve the regulation of lotus seed resistant starch on intestinal flora and the metabolites short-chain fatty acids and bile acids. Taken together, the findings may enhance understanding towards ameliorative effects of resistant starch on food allergy, and offer valuable insights for the exploration of novel anti-allergic bioactive compounds.

Effect of different drying methods on the structure and properties of porous starch

In order to investigate the effects of different drying methods on the properties of porous starch. The present study used four drying methods, namely hot air drying (HD), spray drying (SPD), vacuum freeze drying (FD) and supercritical carbon dioxide drying (SCD) to prepare maize and kudzu porous starch. Findings indicated that the physicochemical properties (e.g., morphology, crystallinity, enthalpy value, porosity, surface area and water absorption capacity as well as dye absorption capacity, particle size) of porous starch were significantly affected by the drying method. Compared with other samples, SCD-treated porous starch exhibited the highest surface areas of the starch (2.943 and 3.139 m2/g corresponding to kudzu and maize, respectively), amylose content (22.02 % and 16.85 % corresponding to kudzu and maize, respectively), MB and NR absorption capacity (90.63 %, 100.26 % and 90.63 %, 100.26 %, corresponding to kudzu ad maize, respectively), and thermal stability, whereas HD-treated porous starch showed the highest water-absorption capacity (123.8 % and 131.31 % corresponding to kudzu and maize, respectively). The dye absorption of the maize and kudzu porous starch was positively correlated with surface area, according to Pearson's correlation analysis. Therefore, in this study, our aim was to explore the effects of different drying methods on the Structure and properties of porous starch, and provide reference for selecting the best drying method for its application in different fields.

Physicochemical properties of a novel chestnut porous starch nanoparticle

A novel chestnut porous starch nanoparticle (PSNP) was successfully synthesized, combining the properties of starch nanoparticle (SNP) and porous starch. The SNP obtained through ultrasonic and acid hydrolysis, exhibited a smaller particle size (173.9 nm) and a higher specific surface area (SSA) compared to native starch. After the synergistic hydrolysis by α-amylase and glucoamylase, the porous structure appeared on the surface of SNP. The prepared PSNP had a size of 286.3 nm and the highest SSA. In the adsorption experiments, PSNP showed higher capacities for adsorbing water, oil and methylene blue (MB) compared to other samples. The acid and enzymatic treatments resulted in a decrease in the levels of total starch content and amylose ratio. Furthermore, the treatments increased the levels of relative crystallinity (RC) and solubility, while decreasing the short-range ordered structure and swelling ratio at high temperatures. It was observed that the SSA of starch granules positively correlated with the MB and water adsorption capacity (WAC), solubility, and RC. These findings highlight the potential of the novel PSNP as an efficient adsorbent for bioactive substances and dyes.

Hydrothermal processes and simultaneous enzymatic hydrolysis in the production of modified cassava starches with porous-surfaces

The amylolytic action of α-amylase and amyloglucosidase has been directly implemented in native cassava starches for the formation of cassava microporous granules with unsatisfactory results, however, its incidence in hydrothermally treated granules has never been evaluated. The effect of hydrothermal processes and simultaneous enzymatic hydrolysis on the physicochemical, morphological and structural properties of native cassava starch was evaluated. Native cassava starch presented a rigid, smooth surface, and was exempt from porosities, whereas hydrothermal processes altered the semicrystalline order and increasing the size and number of pores and increasing the size (4.11 ± 0.09 nm) and volume of pores (0.82 ± 0.00 cm3/g × 10-3). The hydrothermal action followed by enzymatic processes with α-amylase and amyloglucosidase, augmented the processes of internal degradation (endo-erosion) and pore widening (exo-erosion), improving the hydrophilic properties compared to the hydrothermal treatment. Likewise, the hydrothermally process followed by enzymatic hydrolysis for 24 h (HPS + EMS-24) increased the degradation of the amorphous lamellae, consistent with a significant decrease in amylose content. This same dual treatment increased the pore size at 17.68 ± 0.13 nm relative to the native counterpart; therefore, they are considered an effective method in the development of modified cassava starches with porous surfaces.

Application of small angle scattering (SAS) in structural characterisation of casein and casein-based products during digestion

In recent years, small and ultra-small angle scattering techniques, collectively known as small angle scattering (SAS) have been used to study various food structures during the digestion process. These techniques play an important role in structural characterisation due to the non-destructive nature (especially when using neutrons), various in situ capabilities and a large length scale (of 1 nm to ∼20 μm) they cover. The application of these techniques in the structural characterisation of dairy products has expanded significantly in recent years. Casein, a major dairy protein, forms the basis of a wide range of gel structures at different length scales. These gel structures have been extensively researched utilising scattering techniques to obtain structural information at the nano and micron scale that complements electron and confocal microscopy. Especially, neutrons have provided opportunity to study these gels in their natural environment by using various in situ options. One such example is understanding changes in casein gel structures during digestion in the gastrointestinal tract, which is essential for designing personalised food structures for a wide range of food-related diseases and improve health outcomes. In this review, we present an overview of casein gels investigated using small angle and ultra-small angle scattering techniques. We also reviewed their digestion using newly built setups recently employed in various research. To gain a greater understanding of micro and nano-scale structural changes during digestion, such as the effect of digestive juices and mechanical breakdown on structure, new setups for semi-solid food materials are needed to be optimised.

Revealing the reasons for the pasting property changes of rice during aging from the perspective of starch granule disaggregation

BACKGROUND

The pasting properties of rice change markedly after aging, although the mechanism for this still remains unknown. Aged and fresh rice grains were ground and the flours were fractionated by particle size, and then the pasting properties, particle size distribution and microscopic morphology of the heated flour fractions were evaluated.

RESULTS

Compared to the corresponding fresh flour fractions with the same particle size, a lower peak viscosity for those aged flour fractions from 80 μm to 450 μm and a higher peak viscosity for those aged flour fractions from 20 μm to 60 μm were observed. The amounts of smaller particles disaggregated from the aged flour fractions were significantly less and the separated entities were always larger than the corresponding fresh rice fractions.

CONCLUSION

Disaggregation difficulty of starch granules was the reason for the changes in the pasting properties of rice after aging. This finding is helpful for understanding rice aging mechanisms and regulating eating quality of rice flour as an ingredient. © 2022 Society of Chemical Industry.

Effects of high-speed shear and double-enzymatic hydrolysis on the structural and physicochemical properties of rice porous starch

This study aimed to investigate the physicochemical properties of the rice porous starch (HSS-ES) prepared by high-speed shear combined with double-enzymatic (α-amylase and glucoamylase) hydrolysis, and to reveal their mechanism. The analyses of ¹H NMR and amylose content showed that high-speed shear changed the molecular structure of starch and increased the amylose content (up to 20.42 ± 0.04 %). FTIR, XRD and SAXS spectra indicated that high-speed shear did not change the starch crystal configuration but caused a decrease in short-range molecular order and relative crystallinity (24.42 ± 0.06 %), and a loose semi-crystalline lamellar, which were beneficial to the followed double-enzymatic hydrolysis. Therefore, the HSS-ES displayed a superior porous structure and larger specific surface area (2.962 ± 0.002 m²/g) compared with double-enzymatic hydrolyzed porous starch (ES), resulting in the increase of water and oil absorption from 130.79 ± 0.50 % and 109.63 ± 0.71 % to 154.79 ± 1.14 % and 138.40 ± 1.18 %, respectively. In vitro digestion analysis showed that the HSS-ES had good digestive resistance derived from the higher content of slowly digestible and resistant starch. The present study suggested that high-speed shear as an enzymatic hydrolysis pretreatment significantly enhanced the pore formation of rice starch.

A Novel Starch from Talisia floresii Standl Seeds: Characterization of Its Physicochemical, Structural and Thermal Properties

Colok seed (Talisia floresii Standl) represents 80% of the total fruit weight and is obtained from trees that grow mainly in Yucatan Peninsula. The aim of this work was the physicochemical characterization from colok starch seeds as an alternative to conventional sources and to identify its characteristics for potential applications in different industrial sectors. Starch yield was 42.1% with low levels of lipids, ashes and fibers. The amylose content was 33.6 ± 1.15%. The gelatinization temperature was 85 ± 0.25 °C. Color analysis resulted in a starch with an intermediate luminosity, reflecting a dark color. Finally, in morphology, starch granule exhibited an average size of 18.7 μm, spherical, uniform and without fractures. Overall results demonstrated that isolated colok starch can be used in food products that require high processing temperatures, such as sauces, cookies, noodles, bread and food packages.

Physical modification of maize starch by gelatinizations and cold storage

The effects of gelatinization at three selected temperatures (DSC characteristic peaks temperature: TO, TP, and TC) and subsequent cold storage (CS) treatment on structural characteristics, pasting, and rheological properties of maize starch (MS) were investigated. The pasting, rheological properties of MS was changed with the increase of gelatinization temperature from TO to TC, but were not further significantly changed if the gelatinization temperature was higher than TC. Pasting and thermal properties analysis suggested that gelatinization at TC (TC treatment) significantly increased the gelatinization and pasting temperature of MS. Moreover, TC treatment decreased breakdown viscosity by 8.49 times and setback viscosity by 2.53 times. Dynamic rheological measurements revealed that the TC treatment caused the lower G' and G" of MS, and decreased the thickening coefficient by 55.17 %. These results indicated that TC treatment could enhance the thermal stability properties of MS, inhibiting the shear and short-term retrogradation, the shear-thinning behavior of MS. Interestingly, the CS treatment further inhibited the shear and short-term retrogradation and the shear-thinning behavior of MS. The leaked starch molecules aggregate to form a harder structure after gelatinization and starch molecules were further aggregated after CS treatment, these all were hypothesized to be responsible for these results.

Impact of Cassava Starch Varieties on the Physiochemical Change during Enzymatic Hydrolysis

The enzymatic modification of starch extends its industrial use to flavor delivery and probiotic encapsulants, among other uses. However, it is not known how starch from different cassava varieties responds to enzymatic hydrolysis. Starches from two Ecuadorian cassava varieties (INIAP 650, an edible starch, and INIAP 651, an industrial starch) were partially modified at three enzymatic hydrolysis degrees (0%, 30%, and 50%), and their physicochemical properties were assessed. The structural analysis revealed that both varieties showed progressive structural damage as hydrolysis increases, probably due to exo-hydrolysis. However, deeper pores were observed in INIAP 651 with the SEM analysis. The crystallinity percentage obtained by XRD analyses remained constant in INIAP 651 and decreased (by 26%) in INIAP 650 (p < 0.05). In addition, the amylose−lipid complex index in INIAP 650 remained constant, while INIAP 651 increased (p < 0.05) at 30% hydrolysis (by 93%). In both varieties, hydrolysis increased (p < 0.05) the water holding capacity (WHC) (by 10−14%) and the water binding capacity (WBC) (by 16%), but 50% hydrolysis of INIAP 650 was needed to significantly affect these properties. No differences were observed in the varieties’ thermal properties. Regarding the rheological properties, the variety did not influence the changes in the storage module (G′) and the loss modulus (G″) with the hydrolysis (p > 0.05). However, the phase angle decreased significantly (p < 0.05) with the hydrolysis, being higher in the INIAP 650 variety than in the INIAP 651 variety. In general, the results indicate that the variety affects the response of the starch granule to enzymatic hydrolysis (noticeable in the principal component analysis, PCA) and opens up the possibility to modulate starch properties.

Heat-moisture modified blue wheat starch: Physicochemical properties modulated by its multi-scale structure

Blue wheat starch was modified by heat-moisture treatment (HMT) with varying moisture contents (MCs). Changes in physicochemical properties were evaluated on the basis of its multi-scale structure. Following HMTs with MC below 30 %, the starch remained brighter and presented total phenolics content up to 0.20 mg/g. As treating MC increased, structural disruptions became more pronounced, which were characterized by crystallinity loss, lamellae's loosening, hydrogen bonding breakage, and debranching. Furthermore, HMTs decreased the proportion of external A chains of amylopectin. Concomitantly, modified starches showed progressively increased transition temperatures but decreased enthalpy values. Despite the swelling power decrease, HMTs with MC of 15 % showed markedly higher peak viscosity than control, as a result of the more compact semi-crystalline lamellae and homogenous electron distribution. Besides, all HMT-starches showed lowered breakdown and setback. This novel modified starch would be promising ingredients for modulating the viscoelasticity of healthy anti-staling staple foods.

How Does Starch Structure Impact Amylolysis? Review of Current Strategies for Starch Digestibility Study

In vitro digestibility of starch is a common analysis in human nutrition research, and generally consists of performing the hydrolysis of starch by α-amylase in specific conditions. Similar in vitro assays are also used in other research fields, where different methods can be used. Overall, the in vitro hydrolysis of native starch is a bridge between all of these methods. In this literature review, we examine the use of amylolysis assays in recent publications investigating the complex starch structure-amylolysis relation. This review is divided in two parts: (1) a brief review of the factors influencing the hydrolysis of starch and (2) a systematic review of the experimental designs and methods used in publications for the period 2016–2020. The latter reports on starch materials, factors investigated, characterization of the starch hydrolysis kinetics and data analysis techniques. This review shows that the dominant research strategy favors the comparison between a few starch samples most frequently described through crystallinity, granule type, amylose and chain length distribution with marked characteristics. This strategy aims at circumventing the multifactorial aspect of the starch digestion mechanism by focusing on specific features. An alternative strategy relies on computational approaches such as multivariate statistical analysis and machine learning techniques to decipher the role of each factor on amylolysis. While promising to address complexity, the limited use of a computational approach can be explained by the small size of the experimental datasets in most publications. This review shows that key steps towards the production of larger datasets are already available, in particular the generalization of rapid hydrolysis assays and the development of quantification approaches for most analytical results.

Starch-based materials encapsulating food ingredients: Recent advances in fabrication methods and applications

Encapsulation systems have gained significant interest in designing innovative foods, as they allow for the protection and delivery of food ingredients that have health benefits but are unstable during processing, storage and in the upper gastrointestinal tract. Starch is widely available, cheap, biodegradable, edible, and easy to be modified, thus highly suitable for the development of encapsulants. Much efforts have been made to fabricate various types of porous starch and starch particles using different techniques (e.g. enzymatic hydrolysis, aggregation, emulsification, electrohydrodynamic process, supercritical fluid process, and post-processing drying). Such starch-based systems can load, protect, and deliver various food ingredients (e.g. fatty acids, phenolic compounds, carotenoids, flavors, essential oils, irons, vitamins, probiotics, bacteriocins, co-enzymes, and caffeine), exhibiting great potentials in developing foods with tailored flavor, nutrition, sensory properties, and shelf-life. This review surveys recent advances in different aspects of starch-based encapsulation systems including their forms, manufacturing techniques, and applications in foods.

Modulating layer-by-layer assembled sodium alginate-chitosan film properties through incorporation of cellulose nanocrystals with different surface charge densities

In this work, 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanocrystals (TOCNs) were loaded into sodium alginate/chitosan multilayer film as nanofillers to investigate the modulation of the surface charge density of TOCNs on the film properties. First, the surface charge density of TOCNs was controlled by adjusting the carboxyl content and morphological size by varying the oxidant dosage. After oxidation, TOCN with higher surface charge density was observed to display a higher crystallinity, a more open internal structure, a better dispersibility and a slightly weaker thermal stability. In addition, a 15-layer film composed of sodium alginate and chitosan, called (SA/CH)₁₅, was constructed by layer-by-layer assembly. Both in situ deposition monitoring and free-standing multilayer film formation indicated that TOCNs relied on strong electrostatic interactions and hydrogen bonding to achieve a compact and uniform interlayer and a thinner thickness of (SA/CH)₁₅, which was more evident at a high surface charge density. The addition of TOCNs also enhanced the mechanical properties, thermal stability, hydrophobicity, and barrier properties of (SA/CH)₁₅. In particular, the resulting sodium alginate/chitosan multilayer film exhibited an improved packaging performance when nanocomposite was performed using TOCN with a surface charge density of 3.22 ± 0.11 e nm^-2.

Investigation of food microstructure and texture using atomic force microscopy: A review

We review recent applications of atomic force microscopy (AFM) to characterize microstructural and textural properties of food materials. Based on interaction between probe and sample, AFM can image in three dimensions with nanoscale resolution especially in the vertical orientation. When the scanning probe is used as an indenter, mechanical features such as stiffness and elasticity can be analyzed. The linkage between structure and texture can thus be elucidated, providing the basis for many further future applications of AFM. Microstructure of simple systems such as polysaccharides, proteins, or lipids separately, as characterized by AFM, is discussed. Interaction of component mixtures gives rise to novel properties in complex food systems due to development of structure. AFM has been used to explore the morphological characteristics of such complexes and to investigate the effect of such characteristics on properties. Based on insights from such investigations, development of food products and manufacturing can be facilitated. Mechanical analysis is often carried out to evaluate the suitability of natural or artificial materials in food formulations. The textural properties of cellular tissues, food colloids, and biodegradable films can all be explored at nanometer scale, leading to the potential to connect texture to this fine structural level. More profound understanding of natural food materials will enable new classes of fabricated food products to be developed.

The architecture of starch blocklets follows phyllotaxic rules

The starch granule is Nature’s way to store energy in green plants over long periods. Irrespective of their origins, starches display distinct structural features that are the fingerprints of levels of organization over six orders of magnitude. We hypothesized that Nature retains hierarchical material structures at all levels and that some general rules control the morphogenesis of these structures. We considered the occurrence of a «phyllotaxis» like features that would develop at scales ranging from nano to micrometres, and developed a novel geometric model capable of building complex structures from simple components. We applied it, according to the Fibonacci Golden Angle, to form several Golden Spirals, and derived theoretical models to simulate scattering patterns. A GSE, constructed with elements made up of parallel stranded double-helices, displayed shapes, sizes and high compactness reminiscent of the most intriguing structural element: the ‘blocklet’. From the convergence between the experimental findings and the theoretical construction, we suggest that the «phyllotactic» model represents an amylopectin macromolecule, with a high molecular weight. Our results offer a new vision to some previous models of starch. They complete a consistent description of the levels of organization over four orders of magnitude of the starch granule.

Purification, Preliminary Structural Characterization, and In Vitro Inhibitory Effect on Digestive Enzymes by β-Glucan from Qingke (Tibetan Hulless Barley)

Background and Objective. Qingke (Tibetan hulless barley, Hordeum vulgare L.) contains a high content of β-glucan among all the cereal varieties. Although β-glucan has multiple physiological functions, the physiological function of qingke β-glucan was few studied. In this study, the β-glucan was isolated, purified, determined the structural characterization, and measured the inhibitory activity to enzymes correlating blood sugar and lipid. Methods. β-Glucan was isolated from enzymatic aqueous extract of qingke by using deproteinization, decolorization, DEAE-52 column chromatography, and sepharose CL-4B agarose gel column chromatography. The structure of the β-glucan was determined using FT-IR and 13C-NMR spectra analysis, and molecular mass by use of HPSEC-dRI-LS. The kinematic viscosity was measured. The inhibitory effects of this β-glucan on four enzymes were investigated. Results. This β-glucan had a uniform molecular weight of 201,000 Da with β-(1⟶4) as the main chain and β-(1⟶3) as a side chain. The β-glucan presented a relatively strong inhibitory activity on α-glucosidase, moderate inhibition on invertase, and a weak inhibition on α-amylase, whereas it did not inhibit lipase. Conclusion. The study indicates that the enzymatic β-glucan from qingke has the potential as natural auxiliary hypoglycemic additives in functional medicine or foods.

Interfacial Structures of Droplet-Stabilized Emulsions Formed with Whey Protein Microgel Particles as Revealed by Small- and Ultra-Small-Angle Neutron Scattering

Droplet-stabilized emulsions (DSEs) were made from oil droplets coated with whey protein microgel (WPM) particles. The WPM particles with z-average hydrodynamic diameters of 270.9 ± 4.7 and 293.8 ± 6.7 nm were obtained by heating whey proteins with 10 mM phosphate buffer, pH 5.9 (-PB) and no buffer (-NPB), respectively. The primary emulsions coated by WPM-NPB and WPM-PB particles had mass fractal dimensions of ∼2.75, as determined by small- and ultra-small-angle neutron scattering (SANS and USANS). The size of the subsequently formed DSEs (D₃₂ ≈ 7-23 μm), which were stabilized by the primary emulsion droplets, made with either WPM-NPB (termed DSE-NPB) or WPM-PB (termed DSE-PB) was dependent on the concentration of the primary emulsion (10-60 wt %) in the aqueous phase. At the DSE-NPB interface, the adsorbed primary emulsion droplets formed a fractal network with a surface fractal dimension of about 3, indicating a rough interfacial layer. Combined SANS and USANS allowed a comprehensive understanding of the multilength scale structures from WPM particles to DSEs.