•Structure and physicochemical properties for different modified starch-based nanoparticles were investigated.•OS-SSNP had small-sized particles with spherical shape compared to A-ISNP.•OS-SSNP formed a homogenous transparent solution exhibiting better stability than A-ISNP.•OS-SSNP was an effective particle emulsifier for Pickering-type emulsions.The molecular structure and physicochemical characteristions of different modified starch-based nanoparticle from maize varieties (octenylsuccinylation treated soluble starch nanoparticle, OS-SSNP, and acid treated insoluble starch nanoparticle, A-ISNP) were investigated. Compared to A-ISNP, OS-SSNP had small-sized particles with spherical shape. FT-IR analysis showed the similar characteristic absorption bands, except small new peaks after chemical treatment. OS-SSNP suspension was stable with a unimodal distribution regardless of pH used, whereas wider distribution peaks were observed for A-ISNP with the increase of pH. Moreover, OS-SSNP formed a homogenous transparent solution exhibiting better stability than A-ISNP, especially under acidic conditions. OS-SSNP was an effective particle emulsifier for long-term stability of emulsion. The rheological measurements showed the Newtonian flow behavior for OS-SSNP solution and the pseudoplastic behavior for A-ISNP, respectively. Results suggested that it was possible to employ OS-SSNP to produce Pickering-type emulsions with improved properties.Download high-res image (194KB)Download full-size image

•Soluble starch nanoparticle was treated by enzymatic degradation and esterification.•Dual-enzyme pretreatment increased the reaction efficiency of OSA modification.•Position of ester groups in OSA modified starch nanoparticle was elucidated.•Tailor-made OS-starch nanoparticle can improve the emulsion stability.The hypothesis of improving the esterification of sugary maize soluble starch through dual-enzyme pretreatment was investigated. Native starch nanoparticle (NSP) was enzymatically pretreated using β-amylase and transglucosidase (ESP) and then esterified with octenylsuccinic anhydride (OSA). The degree of substitution (DS), reaction efficiency (RE), molecular weight (Mw), molecular density (ρ) and in vitro digestibility were determined. Fourier transform infrared spectroscopy and confocal laser scanning microscopy were used to analyze starch particle and its OS derivatives. The emulsification properties of OS-NSP and OS-ESP were also compared. The results showed that dual-enzyme modification increased the DS and RE of OSA modified starch particle compared with the control. Enzymatic modification had a thinning effect at the surface of starch particle, resulting in lower Mw. The extent of reduction in ρ of OS-ESP was greater than that of OS-NSP. At equivalent DS, OSA modification of EPS was more effective than that of NPS in reducing digestibility. Also, there was brighter fluorescence spheres of OS-ESP in comparison to OS-NSP at equivalent DS, suggesting more OS groups were substituted on the chains near the branch points at less density areas. OS-ESP with higher DS (0.0197) had lower zeta-potential and average particle size for superior emulsion stabilization properties with high stability. The results revealed the OS-starch prepared under dual-enzyme pretreatment was a Pickering particle stabilizer for potential application in encapsulation and delivery of bioactive components.

•Characterisation of sugary maize soluble starch particles subjected to β-amylase degradation was assessed.•β-Amylase degradation had a thinning effect at the surface of soluble starch particle.•Enzyme treatment increased the quantity of shorter chains and α-1,6 linkages.•Modified soluble starch particle is a promising nano-constructed material.In this study, β-amylase degradation was used to modulate the fine structure and intestinal biodegradability of sugary maize soluble starch particles. The remnants from extended β-amylase degradation of soluble starch particles exhibited a resistance to the enzyme action, and the particle size ranged from 30 to 105 nm in diameter. The molecular weight distributions of enzyme treated starch particles and their debranched chain length distributions showed β-amylolysis had a thinning effect at the outmost surface of soluble starch particles, resulting in an increase of DP 2–5 chains through shortening of the external long chains. The percentage of α-1,6 linkages reached up to 14.1%. No significant changes occurred in the IR characteristic peaks of modified starch particles, and the primary chemical structure was preserved. The digestion behaviour showed that enzyme treated starch particle had a low digestion rate, which would help designing highly branched nano-particles as a potential delivery carrier for functional components.

•PLA was firstly reported in pickles including homemade and commercial ones.•The metabolic mechanism of PLA in pickles was elucidated.•This work may provide some new insights into preservation of fermented vegetables.Phenyllactic acid, a phenolic acid phytochemical with the antimicrobial activity, was rarely reported in food besides honey and sourdough. This study evidenced a new food source of phenyllactic acid and elucidated its metabolic mechanism. Phenyllactic acid naturally occurred in Chinese pickles with concentrations ranged from 0.02 to 0.30 mM in 23 pickle samples including homemade and commercial ones. Then, lactic acid bacteria capable of metabolizing phenyllactic acid were screened from each homemade pickle and a promising strain was characterized as Lactobacillus plantarum. Moreover, the investigation of the metabolic mechanism of phenyllactic acid in pickles suggested that the yield of phenyllactic acid was positively related to the content of phenylalanine in food, and the addition of phenylalanine as precursor substance could significantly promote the production of phenyllactic acid. This investigation could provide some insights into the accumulation of phenyllactic acid in pickle for long storage life.

•An extracellular homopolysaccharide with high molecular weight was obtained from Lactobacillus reuteri SK24.003.•The degradation temperature and melting point was 292.6 and 147.7 °C, respectively.•The glucan solution (3.0–9.0%, v/w) has opalescent, milky-white color.•The non-Newtonian pseudoplastic behavior was observed in exopolysaccharide solution.A water soluble exopolysaccharide was obtained from Lactobacillus reuteri SK24.003 and its rheological and structural properties were investigated. The polysaccharide yield reached around 40.8 g/L for 48 h of fermentation. The purified exopolysaccharide was an α-d-glucan with the molecular weight of 2.50 × 107 g/mol. Thermal analysis showed the exopolysaccharide broke down above 200 °C, the weight dramatically lost (around 53.0%) from 230 to 340 °C and the melting point was 147.7 °C with the enthalpy value of 78.4 J/g. The glucan solution (3.0–9.0%, v/w) has an opalescent, milky-white color and the concentration affected the depth of color. The viscosity increased rapidly with concentration in the range of 3.0–20% (w/v) with relatively high viscosity as well as poor solubility at a concentration higher than 20% (w/v). The solution also exhibited the non-Newtonian pseudoplastic behavior with increasing shear rate from 0.01 to 100 l/s. This glucan had a high viscosity in solution and this could make it suitable for usage as gum substitute in some processing food.

•A reduced digestible soluble starch particle was obtained using dual-enzymes modification.•Dual-enzymatic treatment increased the percentage of both DP 2–5 chains and α-1,6 linkages.•Modified soluble starch particle is a promising nano-constructed carrier for functional foods.Sugary maize soluble starch particles were modified by using a combined β-amylase and transglucosidase reaction, and their molecular fine structure and susceptibility to digestive enzymes were investigated. After the dual enzyme treatment, the molecular weight of starch particle decreased from 2.08 × 107 to 0.96 × 107 g/mol accompanied by the appearance of DP 2–5 chains and the degradation of DP > 12 chains, and the percentage of α-1,6 linkages increased from 8.1 to 21.7%. The digestion behaviour of enzyme-treated starch was correlated with the quantity of shorter chains and increased α-1,6 linkages. The data revealed that maize soluble starches subjected to a combined β-amylase and transglucosidase treatment for 60 min or greater, produced novel, highly branched nano-particles with slow digestion and resistance characteristics, which could be used as a potential delivery carrier for functional food components.

•Starch digestibility would be reduced by formulating the green tea extract into real foods.•Fluorescence quenching effect of α-amylase by green tea extract is a consequence of static quenching mechanism.•Epicatechin gallate presented stronger affinity with more number of amino acid residues involved in amylase binding.This study evaluated the inhibitory effects of the green tea extract on human pancreatic α-amylase activity and its molecular mechanism. The green tea extract was composed of epicatechin (59.2%), epigallocatechin gallate (14.6%) and epicatechin gallate (26.2%) as determined by HPLC analysis. Enzyme activity measurement showed that % inhibition and IC50 of the green tea extract (10%, based on starch) were 63.5% and 2.07 mg/ml, respectively. The Michaelis–Menten constant remained unchanged but the maximal velocity decreased from 0.43 (control) to 0.07 mg/(ml × min) (4 mg/ml of the green tea extract), indicating that the green tea extract was an effective inhibitor against α-amylase with a non-competitive mode. The fluorescence data revealed that the green tea extract bound with α-amylase to form a new complex with static quenching mechanism. Docking study showed the epicatechin gallate in the green tea extract presented stronger affinity than epigallocatechin gallate, with more number of amino acid residues involved in amylase binding with hydrogen bonds and Van der Waals forces. Thus, the green tea extract could be used to manipulate starch digestion for potential health benefits.

The structure and properties of bioengineered (1→3)(1→6)-α-d-glucan subjected to endodextranase treatment were investigated. Upon enzyme treatment, OD220 and Mw decreased substantially during the first 60 min and thereafter slowed as the modification progressed. Compared to the native glucan, the modified sample solution had a lighter opalescent, bluish-white color. The morphological analysis revealed that bioengineered glucan produced quite a few small particles after hydrolysis. The molecular weight distribution curve gradually shifted to the low Mw region with a significant broadening distribution, and the chain hydrolysis reaction followed a combination of zeroth- and first-order processes. The NMR results showed some specific α-1,6 linkages of glucan chains were cleaved with enzyme treatment. The viscosity of modified glucan solution was markedly reduced, and the Newtonian plateaus were also observed at high shear rates (10–100 1/s). The above results suggested that the modified (1→3)(1→6)-α-d-glucan showed a tailor-made solution character similar to that of arabic gum and would be used as a novel food gum substitute in the design of artificial carbohydrate-based foods.

The molecular structure and its relationship to in vitro fermentation properties of α-d-glucan from Lactobacillus reuteri SK24.003 were investigated in this study. The chain structure was elucidated by 2D NMR spectroscopy and a possible repeating unit was deduced. During in vitro fecal fermentation, the relatively low initial bacterial population was observed during first 6 h incubation and small increase for α-d-glucan for 12–48 h incubation. A significant decrease in pH (approximately 2.0) was observed for fecal microbiota exposed to α-d-glucan. Acetic acid, propionic acid, n-butyric acid along with total short-chain fatty acid (SCFA) increased upon incubation, and d-glucan was initially fermented well resulting in the higher production of SCFA at 12 h. The n-butyric acid value at 48 h fermentation (1.29 mM) was higher than that of some commercial prebiotic oilosaccharides. These results suggested that α-d-glucan might be efficiently utilized by gut bacteria and may have a positive effect for gastrointestinal health.

•Water-soluble glucopolysaccharide was obtained from sugary maize mutant.•The glucopolysaccharide exhibited a nanoparticle size with the range of 30–80 nm.•The polysaccharide was composed of an α-1,4 backbone and an α-1,6 branched structure.•Digestibility of polysaccharide was influenced by granule size and molecular fine structure.The structure and digestibility of endosperm water-soluble α-glucans from different sugary-1 maize mutants (Zhongtian 8#, Zhongtian 2# and Pintian 8#) were investigated. The yield of pure glucan was in the range of 25.91–34.38%. The α-glucan belonged to a typical native nano-scale particle and the average particle size was in the following order: Zhongtian 8# >Pintian 8# >Zhongtian 2#. The weight-average molar mass of glucans ranged from 1.69 to 2.08 × 107 g/mol. The branch densities and α-1,6 linkages of Zhongtian 8#, Zhongtian 2# and Pintian 8#, were 8.60%, 8.77% and 9.51%, 7.71%, 6.58% and 6.81%, respectively. The resistant starch (10.06%) of Pintian 8# was lower than other two cultivars. The study showed that water-soluble glucan exhibited α-1,4-linked backbone with α-1,6 branch sites and digestibility was influenced by granule size, ratio of α-1,4 to α-1,6 linkages, molecular fine structure in this set of sugary maize mutants.

•Partially maltogenic α-amylase treatment increased the content of slowly digestible starch.•The mechanism of slowly digestible character of starch was revealed.•Maize starch modified using maltogenic α-amylase for 6 h showed a higher SDS content (approximately 20%).In this study, maltogenic α-amylolysis was used to modulate the fine structure of starch responsible for the slow digestion property. The normal maize starch was treated using maltogenic α-amylase for 6 h and showed an increase of slowly digestible starch from 11.1% to 19.6%. Compared to the control starch, the iodine binding analysis showed that the wavelength of maximum absorption and the absorbance was substantially reduced with initial maltogenic α-amylase treatment. The maltogenic α-amylolysis decreased in molecular weight from 32.5 × 107 to 9.0 × 104 g/mol and increased in the number of shorter chains (DP < 13) from 25.5% to 44.8%, which was also accompanied by a reduction of longer chains (DP > 13). The increase in the amount of shorter chains was attributed to the slow digestion property of starch. These results suggest that the normal maize starches modified with partial maltogenic α-amylolysis produced new, fine structures with slow digestible characteristics.

•Biosynthesis of plant steryl laurate using salt hydrate pairs in non-aqueous media was assessed.•Lipase-reaction followed Michaelis–Menten equation with a Ping–Pong Bi–Bi mechanism.•Structures of plant steryl laurate were confirmed by FT-IR and UPLC–MS/MS.•The plant steryl laurate showed good cholesterol-lowering properties in experimental mice.The objective of this work was to produce plant steryl esters with lipase-catalysed esterification using salt hydrate pairs in n-hexane and study its cholesterol-lowering properties. The optimum reaction conditions investigated were the lipase variety (Candida rugosa lipase), fatty acid variety (laurate acid), water activity (aw = 0.764 [Na2SO4/Na2SO4·10H2O]), temperature (45 °C), and enzyme load (10%). The following kinetic parameters were determined: Vmax = 18.41 mmol/min/mg; KA,acid = 0.00407 M; KB,sterol = 0.00447 M; KiA,acid = 0.00205 M; KiB,sterol = 0.00865 M. These data showed that the bioreaction followed the Michaelis–Menten equation with a Ping–Pong Bi–Bi mechanism. FT-IR and MS analyse were adopted to confirm the chemical structure of synthesized plant steryl laurate. Compared with plant sterols, the isolated plant steryl laurate had low melting temperature and higher solubility. The cholesterol-lowering property of plant steryl laurate was also evaluated and demonstrated to decrease serum total cholesterol and low-density lipoprotein cholesterol.

•Grape skin extract is characterised as resveratrol-3-O-glucoside.•Grape skin extract presents good affinity to bind to human α-amylase.•Fluorescence quenching effect of α-amylase by grape skin extract is a consequence of static quenching mechanism.•Grape skin extract interacted with side chain of Asp300 with hydrogen bonds and Van der Waals forces.The objective of this work was to evaluate the structure–function relationship between grape skin extract and human α-amylase. The grape skin extract was characterised as resveratrol-3-O-glucoside by RP-HPLC–ESI-MS, which showed strong inhibition towards α-amylase and the IC50 value was 1.35 mg/ml. The kinetic results demonstrated grape skin extract obeyed the non-competitive mode against amylase. Fluorescence data revealed the ability of grape skin binding to amylase belonged to static quenching mechanism with a complex formation and there was only one binding site in α-amylase for grape skin extract. Docking study showed a best pose with total energy value of −118.3 kJ/mol and grape skin extract interacted with side chain of Asp300 with hydrogen bonds and Van der Waals forces. This preliminary observation provides the basis for further evaluation of the suitability of grape skin extract as natural inhibitor with potential health benefits.

•A neutral exopolysaccharide was obtained from Lactobacillus reuteri SK24.003.•Monosaccharide composition analysis confirmed that exopolysaccharide consisted of glucose residues only.•The polysaccharide possessed predominantly α-(1→4) glycosidic linkages, with fewer α-(1→6) glycosidic linkages and α-(1→4,6) branching points.•A promising application of exopolysaccharide was provided.The structural features of a neutral extracellular glucan derived from Lactobacillus reuteri SK24.003 were investigated. Colonies of the strain SK24.003 exhibited a creamy and slimy morphological appearance on MRS solid medium and were identified as L. reuteri via 16S rDNA sequence analysis. The exopolysaccharide produced from sucrose was composed exclusively of glucose, and the weight-average molecular weight was 4.31 × 107 g/mol. The polysaccharide exhibited an α-(1→4) backbone with an α-(1→6) branch at every fourth residue, as deduced from both NMR and GC–MS data. The exopolysaccharide acted as a natural steel corrosion inhibitor. The results suggested that a novel α-glucan produced by L. reuteri SK24.00 could be broadly used in food and material field.

•Partially β-amylase treatment increased the content of slowly digestible starch.•Slow digestion property was influenced by shorter chain fraction and α-1, 6 linkages of starch.•A maximum SDS content (24.38%) was obtained using β-amylolysis over 2 h.In this study, partial β-amylolysis was used to modulate the starch fine structure responsible for the slow digestion property of starch. Normal maize starch modified using β-amylase for 2 h showed an increase of slowly digestible starch from 11.16% to 24.38%. The β-amylase treatment increased the amylose content from 28.4% to 32.5%, decreased the molecular weight from 32.5 × 107 to 3.8 × 105 g/mol and increased the number of shorter chains (DP < 13) from 25.5% to 41.1%, accompanied by a reduction of longer chains (DP > 13). 1H NMR spectra showed an increase of α-1,6 linkages from 7.4% to 10.1% in the enzyme treated starches. Both the increase in the amount of shorter chains and the increase in α-1,6 linkages were attributed to the slow digestion property of starch. These results suggest that starches treated with partial β-amylolysis retain a branched structure and slow digestibility.

The octenylsuccinic groups in esterification-modified sugary maize soluble starches with a low (0.0191) or high (0.0504) degree of substitution (DS) were investigated by amyloglucosidase hydrolysis followed by a combination of chemical and physical analysis. The results showed the zeta-potential remained at approximately the same value regardless of excessive hydrolysis. The weight-average molecular weight decreased rapidly and reached 1.22 × 107 and 1.60 × 107 g/mol after 120 min for low-DS and high-DS octenylsuccinic anhydride (OSA) modified starch, respectively. The pattern of z-average radius of gyration as well as particle size change was similar to that of Mw, and z-average radius of gyration decreased much more slowly, especially for high-DS OSA starch. Compared to native starch, two characteristic absorption peaks at 1726.76 and 1571.83 cm–1 were observed in FT-IR spectra, and the intensity of absorption peaks increased with increasing DS. The NMR results showed that OSA starch had several additional peaks at 0.8–3.0 ppm and a shoulder at 5.56 ppm for OSA substituents, which were grafted at O-2 and O-3 positions in soluble starch. The even distribution of OSA groups in the center area of soluble starch particle has been directly shown under CLSM. Most substitutions were located near branching points of soluble starch particles for a low-DS modified starch, whereas the substituted ester groups were located near branching points as well as at the nonreducing ends in OSA starch with a high DS.

•Theaflavins presents good affinity to bind to human α-Amylase.•Theaflavins interacted with side chain of Asp300 with hydrogen bonds and van der waals forces.•The galloylated theaflavin has higher binding affinity with α-Amylase than non-galloylated theaflavin.The relationship between structure and activity of theaflavins against human pancreatic α-Amylase was investigated by in vitro and in silico methods. The IC50 and total energy value showed that inhibitory effects followed the order: theaflavin-3, 3’-di-O-gallate > theaflavin-3’-O-gallate > theaflavin-3-O-gallate > theaflavin. Inhibitory activity was depended on hydroxyl groups and galloyl moieties of theaflavins to interact with the catalytic residues of the active site of α-Amylase by hydrogen bonds and π–π (aromatic–aromatic) interactions. The galloylated theaflavin has higher binding affinity with α-Amylase than non-galloylated theaflavin. The study showed that theaflavins might act as natural enzyme inhibitors with potential health benefits, which provide a foundation for designing novel functional food for effective controlling of starch digestion and postprandial glucose levels.

Starches isolated from two types of Cynanchum auriculatum Royle ex Wight roots grown in China (BW 201001 and HSW 6-18) were investigated and compared to commercial potato starch. The protein, lipid, ash and amylose content of BW 201001 and HSW 6-18 starches were 0.12%, 0.15%, 0.16%, 17.48%, and 0.15%, 0.13%, 0.11%, 21.10%, respectively. The starch granules were irregular with a round or polygonal shape and a size ranging between 5 and 15 μm. Compared to HSW 6-18 starch, BW 201001 starch had a higher solubility, water binding capacity, average chain length, and proportion of B1 chains, and a lower swelling power, syneresis, and proportion of A chains. Both starches showed the characteristic B type X-ray pattern. The degree of crystallinity and R(1047/1022) of BW 201001 and HSW 6-18 were 43.03%, 0.50, and 38.78%, 0.42, respectively. Gelatinisation temperatures followed the order of BW 201001 > HSW 6-18. The peak viscosity, setback, and final viscosity of BW 201001 were lower than those of HSW 6-18 starch. Both starches exhibited lower RDS and higher RS, which was related to their crystal and molecular structures.Highlights► Characteristics of Cynanchum auriculatum Royle ex Wight starches were assessed. ► Physicochemical properties and nutritional fractions varied from different cultivars. ► Structural variations among starches influenced their properties. ► Digestibility were dependent on crystal structure and long-chain amylopectin.

In this study, the molecular structure of acid-treated waxy maize starch residues was investigated, and the in vitro digestibility of the residues with 2.2 N HCl at 35 °C for different time periods, was assessed. The granular appearance of waxy maize starch was destroyed and small fractions formed aggregates. A change in chain-length distribution profiles occurred with the degradation of shortest A chains and long B chains in amylopectin. The rise in the ratio of absorbance height at 1047 cm−1 to the height at 1022 cm−1, the intensities of major peaks, Xc, Tp, Tc, and ΔH were observed during mild acid hydrolysis, but the X-ray diffraction patterns displayed A-type for all starches. The amount of rapidly digestible starch increased, whereas the amounts of slowly digestible and resistant starch decreased. These results demonstrate that the amorphous regions of starch granules, including the shortest A chains and long B chains, are preferentially hydrolysed and affect the slow digestion and resistance properties of waxy maize starch.Research highlights► Amorphous regions of starch granules is preferentially acid degraded. ► Shortest A chains and long B chains affect the digestion properties of starch. ► Slowly digestible starch mainly consists of amorphous and ordered crystalline regions.

It is well known that high hydrostatic pressure (HHP) treatment will increase the shelf life of different fruit. However, texture changes associated with these responses are not well understood in vegetables. The objective of this work was to study the effects of HHP treatment on quality and lignification of minimally processed water bamboo shoots cultivated in China. Water bamboo shoots were exposed to HHP treatment for 10 min at room temperature (25 °C) and then stored for 7 days at 4 °C. Firmness, lignin and cellulose contents, and enzyme activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD), were investigated during storage. An increase in firmness of water bamboo shoots was observed, and this increase after harvest was positively correlated with higher lignin and cellulose contents, r = 0.96, P < 0.05; r = 0.98, P < 0.01 respectively. Accumulation of lignin in flesh tissue was also positively correlated with activities of PAL and POD, r = 0.97, P < 0.01; r = 0.90, P < 0.05 respectively. PAL and POD activities showed a persistent rise over the whole 7 days. HHP treatment resulted in lower firmness, delayed activities of PAL and POD, and retardation of lignin and cellulose accumulation. These studies showed that HHP might be an efficient nonthermal alternative for extended shelf life of water bamboo shoots.Research highlights▶ HPP increase the shelf life of water bamboo shoots. ▶ HPP treatment lessens the firmness, activities of PAL and POD. ▶ HPP delays the lignin and cellulose accumulation.

•Biological macromolecule delivery system has gained increasing interest recently.•They may be formed by coacervation, electrostatic interaction and crosslinking.•Several novel materials for preparing delivery systems are introduced.•Desired functionality can be realized by using these delivery systems.There is a growing interest in using biological macromolecules based delivery systems such as hydrogels, nanoparticles, and coacervates to encapsulate, protect and release hydrophobic nutraceuticals in order to achieve desired functionality. In this article, we reviewed recent progress in the fabrication and functional performance of delivery systems based on these macromolecules. Physicochemical characteristics of macromolecules such as proteins and carbohydrates used as building blocks are discussed. In particular, some novel macromolecules are introduced. An overview of strategies for fabricating biological macromolecule delivery systems is given. Potential benefits of certain biological macromolecules based delivery system are highlighted. At last, we summarized potential challenges for future development of biological macromolecules based delivery systems.

•O/W emulsions were prepared using different hydrophobic maize starches as stabilizers.•Rheological properties, microstructure and physical stability of the emulsions were investigated.•An emulsion with high stability could be prepared using OS-SMSS.•Schematic models of emulsions stabilized by different hydrophobic starches were illustrated.The molecular structure, rheological properties, microstructure and physical stability of oil-in-water emulsions using octenyl succinic-sugary maize soluble starch (OS-SMSS) were investigated and compared with two commercial OS-starches (HI-CAP 100 and Purity Gum 2000). The degree of substitution (DS), weight-average molecular weight (Mw) and z-root mean square radius of gyration (Rz) of OS-SMSS, HI-CAP 100 and Purity Gum 2000 were 0.0050, 223.4 × 105 g/mol and 38.8 nm, 0.0037, 9.6 × 105 g/mol and 29.3 nm, and 0.0031, 31.3 × 105 g/mol and 39.6 nm, respectively. FT-IR spectra showed two new absorption bands at 1725 and 1570 cm−1 from OS ester linkage in all tested samples. The emulsion with OS-SMSS exhibited a pseudoplastic behavior over the whole shear rate range, whereas other two emulsions showed a similar Newtonian fluid. All hydrophobic starch stabilized emulsions satisfied the Herschel–Bulkley model. All emulsions displayed storage modulus (G′) was higher than loss modulus (G″), and only G′ and G″ of OS-SMSS stabilized emulsion were independent of frequency. The volume-average droplet size (d43) value of emulsions stabilized by three modified starches was 27.9, 15.2 and 24.4 μm, respectively. During 4 weeks storage, lower change in d43 of emulsion with OS-SMSS was observed. The above results with schematic models of emulsions suggested that an emulsion with high stability could be prepared using 3% of OS-SMSS due to the formation of high density and thick nanoparticle layer at the interface, indicating OS-SMSS was a Pickering emulsion stabilizer for good long-term stability.

•Food grade O/W Pickering emulsions stabilized by different modified starch-based nanoparticles were prepared.•Rheological behaviour and microstructure of O/W emulsions were investigated.•Starch-based nanoparticles were adsorbed at O/W interface to form a barrier film.•OSA-SSNP could be used as a novel particle stabilizer for improving food emulsion quality.The aim of present study was to study the medium-chain triacylglycerol-in-water (O/W) Pickering emulsion stabilized using different modified starch-based nanoparticles (octenylsuccinylation treated soluble starch nanoparticle, OSA-SSNP, and insoluble starch nanoparticle, ISNP). The major factors for affecting the system stability, rheological behaviour and microstructure of the emulsions were also investigated. The parameters of the O/W emulsions stabilized by OSA-SSNP or ISNP were selected as follows: 3.0% of starch nanoparticles concentration, 50% of MCT fraction and 7.0 of system pH. The rheological properties indicated that both emulsions displayed shear-thinning behaviour as a non-Newtonian fluid. For OSA-SSNP, the viscosities of the emulsion were higher than those of ISNP throughout shear rate range for the same condition. The plot of droplet size distribution for emulsion stabilized OSA-SSNP appeared as a single narrow peak, whereas a broader droplet size distribution with bimodal pattern was observed for emulsion stabilized ISNP. The microscopy results showed that both OSA-SSNP and ISNP were adsorbed at oil-water interface to form a barrier film and retard the phase separation. When emulsion was stored for 30 d, no phase separation was detected for O/W emulsion, revealing high stability of emulsion stabilized by both OSA-SSNP and ISNP.

•A glucansucrase was obtained from Lactobacillus reuteri SK24.003.•Enzymological characterisations of glucansucrase were investigated.•Glucansucrase synthesized 1,6-,1,4-α-d-glucan with Mw of 2.5 × 107 g/mol from sucrose.•Maltose acceptor products by glucansucrase showed DP3, DP4 and DP5 analogues.Glucansucrase was obtained from Lactobacillus reuteri SK24.003 and its characterizations and in vitro biosynthesis for glucose polymer and oligosaccharides were investigated. The final specific activity of glucansucrase was 1.3 IU/mg protein with 8.6-fold purification and 8.7% recovery. The molecular weight of purified enzyme was 166.0 kDa. The glucansucrase exhibited optimum activity at 30–35 °C, whereas the maximum activity was obtained at pH 5.0–5.5. The double-charged ions including Mg2+, Mn2+, Ni2+, Co2+, Ca2+, Fe2+ and Zn2+ activated the glucansucrase activities and Ca2+ ion highly stimulated the activity by approximately 4 times. Km, Vmax and kcat of purified glucansucrase were calculated to be 3.7 mM, 0.8 IU/mg and 18.2 1/s, respectively. For in vitro biosynthesis, glucansucrase synthesized 1,6-,1,4-α-d-glucan with a molecular weight of 2.5 × 107 g/mol from sucrose as initial primer. Moreover, maltose acceptor-products synthesized by glucansucrase were composed of panose, maltotriose, maltotetraose, tetrasaccharide and pentasaccharide products analogues with an α-1,4/α-1,6 alternating structure.