In vitro digestion of nanoscale starch particles and evolution of thermal, morphological, and structural characteristics

Thermal stability and in vitro digestive behavior of Pickering emulsion stabilized by high-amylose starch nanocrystals

In this study, high-amylose starch (HAS) was processed using sulfuric acid-ultrasonic cross-linking to produce high-amylose starch nanocrystals (HASNC). These nanocrystals were used to stabilize Pickering emulsions and assess their effectiveness in encapsulating β-carotene. Normal starch nanocrystals (NSNC) were prepared similarly for comparison. The HASNC retained key HAS properties, such as heat and enzyme resistance, providing several advantages to HASNC-stabilized emulsions. First, after exposure to 100 °C heat and in vitro tests simulating the mouth and stomach, the HASNC-stabilized emulsions demonstrated significantly greater stability and higher β-carotene retention compared to the NSNC-stabilized emulsions. This enhanced stability is attributed to the lower gelatinization degree and increased resistance to α-amylase hydrolysis of HASNC, which provides stronger steric stabilization of the oil droplets. Second, during in vitro small intestine tests, the greater enzyme resistance of HASNC allowed for the formation of a denser barrier around the oil droplets, effectively preventing lipase and bile salts from contacting the oil droplets. This led to a reduced rate and extent of lipid digestion and facilitated a sustained-release effect. Consequently, HASNC, as a starch-based emulsifier, show great potential as an effective delivery system for the sustained release of bioactive compounds.

Enzymatically and chemically starch nanoparticles preparation using ultrasonication, precipitation and lyophilization post-treatments: Screening and characterization

Starch nanoparticles (SNPs) have been used in food emulsions as natural stabilizer and emulsifier. SNPs in colloidal form were produced using enzymatically, acidic and alkaline hydrolyses in combination to ultrasonication and precipitation methods. X-Ray diffraction test for produced SNPs indicated that enzymatically and acidic prepared SNPs had amorphous structure while, the resulted SNPs using alkaline hydrolysis had lower relatively crystallinity. Results indicated that, enzymatically prepared SNPs, had minimum particle size (225 ± 10 nm) and polydispersity index (0.472 ± 0.05), and maximum zeta potential (-26.3 ± 1 mV), antioxidant activity (3.36 ± 0.05 %) and specific surface area (1.8 ± 0.1 m2g-1). Transmission electron microscopy revealed that prepared SNPs had spherical shape and enzymatically prepared SNPs had mean particle size of <100 nm. SNPs in powder form were prepared using freeze drying (pressure and temperature of 100 Pa and - 70 °C). Atomic force microscopy results demonstrated that starch granules had smooth surface, with polyhedral shape and particle size ranging 5 to 25 μm, and after hydrolysis, SNPs had particle size in nanometer scale. Emulsion ability test indicated that oil separation time from the prepared emulsions containing 10 % (W/V) starch, and enzymatically, acidic and alkaline prepared SNPs powder were 41, 70, 82 and 101 s, respectively.

Addition of Canna edulis starch and starch nanoparticles to stabilized Pickering emulsions: In vitro digestion and fecal fermentation

Starch nanoparticles (SNPs) were prepared through acid hydrolysis of Canna edulis native starch and modified with octenyl succinic anhydride (OSA) to yield OS-starch and OS-SNPs. These modified particles were used to stabilize curcumin-loaded Pickering emulsions. Effects on gut microbiota during in vitro fecal fermentation were examined. The surface of OS-starch exhibits a porous structure, while OS-SNPs display layered grooves. OSA modification was confirmed by Fourier transform infrared spectroscopy (with peaks at 1728 cm-1 and 1573 cm-1) and proton nuclear magnetic resonance spectra (0.5-2 ppm). The degree of substitution for OS-starch and OS-SNPs is 0.0106 ± 0.0004 and 0.0079 ± 0.0003, respectively. Following modification, the crystallinity decreased from 35.69 ± 0.46 % (native starch) to 30.17 ± 0.70 % (OS-starch), SNPs decreased from 45.87 ± 0.89 % to 43.63 ± 0.64 % (OS-SNPs). Contact angles for OS-starch and OS-SNPs are 77.47 ± 1.78 and 55.57 ± 0.21, respectively. OS-SNPs exhibited superior emulsification properties compared to OS-starch, forming stable Pickering emulsions with pseudoplastic fluid behavior and enhanced curcumin storage protection over 14 days (60.88 ± 4.26 %) with controlled release. Stabilizing Pickering emulsions with OS-starch and OS-SNPs positively affected on gut microbiota and improved the intestinal environment, showing promise for their application in transportation systems and innovative prebiotic food formulations.

Digestion kinetics and molecular structural evolution during in vitro digestion of green banana (cv. Giant Cavendish) starch nanoparticles

Knowledge of digestion mechanism of starch nanoparticles are crucial for their utilization and potential applications. In this study, molecular structural evolution and digestion kinetics of starch nanoparticles from green banana (GBSNPs) during digestion (0-180 min) was investigated. Distinctive topographic changes of the GBSNPs during digestion with decreased particle size and increased surface roughness were detected. The GBSNPs showed markedly decreased average molecular weight and polydispersity in the initial digestion phase (0-20 min), and these two structural characteristics remained nearly unchanged thereafter. The GBSNPs exhibited a B-type polymorph throughout digestion, while their crystallinity decreased with increasing digestion duration. The infrared spectra revealed that the initial digestion phase led to the increased absorbance ratios 1047/1022 and 1047/1035 cm^-1, reflecting the markedly increased short-range molecular order that was substantiated by the blue-shifting of COH-bending band. Logarithm of slope analysis of digestogram revealed that the GBSNPs were digested by a two-phase process that reflected the surface barrier effect exerted by the increased short-range order. The short-range molecular order strengthening induced from the initial digestion phase was responsible for the increased enzymatic resistance. The results can help to elucidate the gastrointestinal fate of starch nanoparticles for their potential applications as health-promoting ingredients.

Effects of Debranching Conditions and Annealing Treatment on the Formation of Starch Nanoparticles and Their Physicochemical Characteristics

Starch nanoparticles (SNPs) have unique attributes that make them suitable for specific applications. In this study, we assessed the optimum conditions for the fabrication of SNPs from the rice starches of low- (TCSG2) and medium-amylose rice lines (TK11) using pullulanase debranching combined with annealing treatment and evaluated their physicochemical and digestion properties. The highest crystalline SNP percent recoveries of 15.1 and 11.7% were obtained from TK11 and TCSG2, respectively, under the following debranching conditions: 540-630 NPUN/g, pH 5.0, 60 °C, and 12 h. The percent recovery of the crystalline SNPs by the combined modification of the debranching and the annealing treatment with an extended annealing incubation prepared from TK11 and TCSG2 was significantly increased to 25.7 and 23.8%, respectively. The modified starches from TK11 had better percent recovery of the crystalline SNPs than those from TCSG2. They exhibited a higher weight-average molecular weight (Mw) and a broader/bimodal molecular weight distribution with a higher polydispersity (PDI) (Mw = 92.76-92.69 kDa; PDI = 4.4) than those from TCSG2 (Mw = 7.13-7.15 kDa; PDI = 1.7). Compared to the native counterparts, the color analyses showed that the modified starches from TK11 and TCSG2 exhibited decreased brightness (L*)/whiteness index (WI) values with marked color difference values (∆E) ranging between 6.32 and 9.39 and 10.67 and 11.32, respectively, presumably due to the protein corona formed on the surface of SNPs which induced the browning reaction during the treatments. The pasting properties revealed that the modified starches displayed restricted swelling power with extremely low pasting viscosities, reflecting that they were highly thermally stable. The modified starches, especially those treated with an extended annealing incubation, exhibited marked decreases in the rate and extent of digestion and estimated glycemic index due to the honeycomb-like agglomerates comprising an assembly of densely packed SNPs. The results could provide helpful information for the preparation and characterization of the crystalline SNPs for potential applications such as emulsion stabilizers for Pickering emulsion and health-promoting ingredients.

Starch Nanoparticles: Preparation, Properties and Applications

Starch as a natural polymer is abundant and widely used in various industries around the world. In general, the preparation methods for starch nanoparticles (SNPs) can be classified into 'top-down' and 'bottom-up' methods. SNPs can be produced in smaller sizes and used to improve the functional properties of starch. Thus, they are considered for the various opportunities to improve the quality of product development with starch. This literature study presents information and reviews regarding SNPs, their general preparation methods, characteristics of the resulting SNPs and their applications, especially in food systems, such as Pickering emulsion, bioplastic filler, antimicrobial agent, fat replacer and encapsulating agent. The aspects related to the properties of SNPs and information on the extent of their utilisation are reviewed in this study. The findings can be utilised and encouraged by other researchers to develop and expand the applications of SNPs.

Influence of native cellulose, microcrystalline cellulose and soluble cellodextrin on inhibition of starch digestibility

Cellulose is a major component of dietary fiber and it is proved to influence starch digestibility. The effects of native cellulose (NC), microcrystalline cellulose (MC), soluble cellodextrin (SC) on starch digestion have not been clearly elucidated. In this study, three types of cellulose with representative molecular weights (NC, 422500 Da; MC, 27750 Da; SC, 2202 Da) were prepared and their effects on starch digestion, glucose diffusion, α-amylase and amyloglucosidase activity were compared. The results suggested SC inhibited starch digestibility to a greater degree than those of NC and MC. When addition of SC reached 3 %, rapidly digestible starch proportion decreased from 31.2 % to 11.3 % and resistant starch proportion increased from 15.0 % to 58.0 %. Notably, hindrance effects of SC on glucose diffusion were higher than those of NC and MC. Moreover, SC reduced activity of α-amylase and amyloglucosidase to a larger extent than those of MC and NC. With the effect of starch digestion inhibition, NC, MC and SC could be utilized as functional food ingredients. Especially, the soluble property and the highest starch digestion inhibition ability of SC favors its application in food industry.

Understanding the aggregation structure, digestive and rheological properties of corn, potato, and pea starches modified by ultrasonic frequency

Corn starch (CS), potato starch (PtS), and pea starch (PS) were modified by ultrasonic frequency (codes as UFCS, UFPtS and UFPS), and changes in aggregation structure, digestibility and rheology were investigated. For UFCS, the apparent amylose content and gelatinization enthalpy (∆H) decreased, while the R1047/1022 values and relative crystallinity (RC) increased under lower ultrasonic frequencies (20 kHz and 25 kHz). For UFPtS, the apparent amylose content, R1047/1022 values and RC increased, while the ∆H decreased under a higher ultrasonic frequency (28 kHz). For UFPS, the apparent amylose content, R1047/1022 values, RC, ∆H decreased at 20 kHz, 25 kHz and 28 kHz. Cracks were observed on the surface of UFCS, UFPtS and UFPS. These aggregation structure changes increased the resistant starch content to 31.11% (20 kHz) and 26.45% (25 kHz) for UFCS and to 39.68% (28 kHz) for UFPtS, but decreased the resistant starch content to 18.46% (28 kHz) for UFPS. Consistency coefficient, storage modulus, and loss modulus of UFCS, UFPtS and UFPS increased, while the flow behavior index and damping factor decreased. Results indicated that CS, PtS and PS had diverse digestion and rheology behaviors after ultrasonic frequency modification, which fulfilled different demands in starch-based products.

Starch-lipid interaction alters the molecular structure and ultimate starch bioavailability: A comprehensive review

Starch bioavailability which results in eliciting postprandial glycaemic response, is a trait of great significance and is majorly influenced by the physical interaction among the matrix components governed by their molecular structure as well as dynamics. Among physical interactions limiting starch bioavailability, starch and any guest molecules like lipid interact together to alter the molecular structure into a compact V-type arrangement endorsing the processed crystallinity, thus limiting carbolytic enzymatic digestion and further bioavailability. Considering the importance of starch-lipid dynamics affecting bioavailability, intensive research based on endogenous (internal lipids which are embedded into the food matrix) as well as exogenous (those are added from outside into the food matrix during processing like cooking) lipids have been carried out, endorsing physical interactions at colloidal and microstructural levels. The shared insights on such binary (starch-lipid) interactions revealed the evolution of characterization techniques as well as their role on altering the functional and nutritional value. It is very much vital to have a thorough understanding about the mechanisms on the molecular level to make use of these matrix interactions in the most efficient way, while certain basic questions are still remaining unaddressed. Do starch - lipid complexation affects the ultimate starch bioavailability? If so, then whether such complexation ability depends on amylose - fatty acid/lipid content? Whether the complexation is influenced further by fatty acid type/concentration/chain length or saturation? Further comprehending this, whether the altered bioavailability by binary (starch-lipid) could further be affected by ternary (starch-lipid-protein) and quaternary (starch-lipid-protein-phenolics) interactions are also discussed in this comprehensive review.

Starch nanoparticles prepared by enzymatic hydrolysis and self-assembly of short-chain glucans

Enzymatic hydrolysis and self-assembly are considered promising methods for preparation of starch nanoparticles (SNPs) because they are environmentally friendly, and time- and cost-effective. These methods are based on the self-assembly of short-chain glucans released from the α-1,6 bonds in amylopectin. Since their discovery, many studies have described the structural and physicochemical properties of self-assembled SNPs. Self-assembled SNPs can be prepared by two methods: using only the soluble portion containing the short-chain glucans, or using the whole hydrolyzate including both insoluble and soluble fractions. Although the structural and physical properties of self-assembled SNPs can be attributed to the composition of the hydrolyzates that participate in self-assembly, this aspect has not yet been discussed. This review focuses on SNPs self-assembled with only soluble short-chain glucans and addresses their characteristics, including formation mechanisms as well as structural and physicochemical properties, compared with SNPs prepared with total hydrolyzates.

In vitro inhibition of pancreatic α-amylase by spherical and polygonal starch nanoparticles

Nanoparticles are novel and fascinating materials for tuning the activities of enzymes.

Preparation of Hollow Biopolymer Nanospheres Employing Starch Nanoparticle Templates for Enhancement of Phenolic Acid Antioxidant Activities

Phenolic acids have been extensively studied because of their bioactive properties and disease prevention and control capacities. However, undesired odors and taste, low aqueous solubility, and thermal and ultraviolet (UV) light instability severely restrict their application. The aim of this work was to evaluate the enhancement in antioxidative activities of phenolic acids in hollow nanospheres and their stability in terms of their antioxidative activities under harsh conditions. For the first time, we have successfully fabricated hollow short linear glucan (SLG)@gum arabic (GA) nanospheres and hollow in situ SLG/GA hybrid nanospheres by removing the sacrificial starch nanoparticle templates through α-amylase treatment and Ostwald ripening. These two hollow nanospheres had a huge cavity area for the encapsulation of phenolic acids, and their loading capacities were >20%. Furthermore, they can be used as nanoreactors to immobilize phenolic acids, enhance their antioxidative activities, and improve their stability when exposed to high salt concentrations, UV light, or heat treatments.

Designing biopolymer microgels to encapsulate, protect and deliver bioactive components: Physicochemical aspects

Biopolymer microgels have considerable potential for their ability to encapsulate, protect, and release bioactive components. Biopolymer microgels are small particles (typically 100nm to 1000μm) whose interior consists of a three-dimensional network of cross-linked biopolymer molecules that traps a considerable amount of solvent. This type of particle is also sometimes referred to as a nanogel, hydrogel bead, biopolymer particles, or microsphere. Biopolymer microgels are typically prepared using a two-step process involving particle formation and particle gelation. This article reviews the major constituents and fabrication methods that can be used to prepare microgels, highlighting their advantages and disadvantages. It then provides an overview of the most important characteristics of microgel particles (such as size, shape, structure, composition, and electrical properties), and describes how these parameters can be manipulated to control the physicochemical properties and functional attributes of microgel suspensions (such as appearance, stability, rheology, and release profiles). Finally, recent examples of the utilization of biopolymer microgels to encapsulate, protect, or release bioactive agents, such as pharmaceuticals, nutraceuticals, enzymes, flavors, and probiotics is given.