Understanding the crystal structure of lotus seed amylose–long-chain fatty acid complexes prepared by high hydrostatic pressure

Effect of safflower seed oil on the molecular structural and enzyme hydrolysis properties of maize starch-lipid complexes

To investigate the impact of safflower seed oil on the structural and digestive properties of complexes formed by fatty acids of varying chain lengths with maize starch, the starch-fatty acid ternary complexes were prepared by a hydrothermal method. The results indicated that safflower seed oil inhibited the complexation of relatively short-chain fatty acids (C10:0, C12:0, and C16:0) with starch, and promoted the complexation of long-chain fatty acids (C18:0). Intriguingly, safflower seed oil showed no significant impact on the formation of linoleic acid (C18:2) complexes, suggesting selective interactions within the starch-fatty acid complexes. In addition, the addition of safflower seed oil did not affect the thermal stability of the complexes, but significantly improved the anti-digestibility properties of the starch-complexes in each group, with the RS content reaching 59.08 % in the C16:0 group. In conclusion, this study provides insights for the development of high-quality resist starch-lipid ternary complexes.

Structural and physicochemical properties of debranched lotus seed starch treated with high hydrostatic pressure

Lotus seeds represent a significant economic crop and are abundant in starch. To further enhance their application value, this study investigates the structural characteristics of lotus seed starch (LS) under the combined influence of pullulanase and high hydrostatic pressure (HHP). Pullulanase increased amylose content from 39.80 % to 72.26 %, and HHP increased amylose content further. LS crystals changed from C-type to B-type, and the ordered structure of LS was destroyed by enzymatic hydrolysis, and amylose single helix and partial double helix structure were formed. At low concentration, lotus seed amylose single helix tends to form amylose double helix structure with itself. At high concentrations, they tend to aggregate, forming a network structure with large surface area and loose order. HHP destroys the double helix structure of amylose, resulting in the decrease of starch crystallinity. These findings provide new insights into improving the processing properties and application range of lotus seed starch.

High hydrostatic pressure modulates the digestive properties of rice starch-gallic acid composites by boosting non-inclusion complexation

Influencing the starch postprandial glycemia via interventions that are sourced from natural plant materials has gained attention recently. Amylose present in starch is reported to form complexes with small ligands such as gallic acid (GA) through a conformational change that are digested slowly and contribute to the formation of resistant starch. In this study, the molecular interactions, multi-scale structure and in vitro digestion properties of normal neat rice starch and rice starch-GA composites (2, 5 % w/v) obtained either by high hydrostatic pressure (HHP) or thermal (T) treatment were compared. The multi-scale structure changes experienced by the rice starch gels (neat and composite) during simulated oro-gastrointestinal (OGIT) digestion were also characterised. Overall, formation of the V7 type inclusion complex was demonstrated in the composite gels processed by HHP and T, although the main molecular interactions found in the composites were non-inclusion complexes. Sample A-GA-5-HHP formed gels with a unique microstructure, whilst also displaying a significant increase of the resistant starch fraction (∼13 %) and a large decrease of the rapidly digestible starch fraction than A-GA-5-T (p < 0.05). The lower digestibility in A-GA-5-HHP was attributed to increased molecular interactions between amylose and GA, as suggested by the greater intensity peak at 3520 cm-1 in the FTIR, and the downfield chemical shifts (0.12 ppm) in the 13C NMR spectra. Our findings indicate that HHP gelatinisation of starch-GA composites represents a promising approach for the design of novel starch-based systems with distinct microstructure and digestion characteristics.

Effects of different fatty acids on the structure, physicochemical properties, and in vitro digestibility of Chinese yam resistant starch-lipid complexes

Nine CYRS-FA complexes were prepared by resistant starch in Chinese yam (CYRS) and nine fatty acids (FAs) with different chain lengths and degrees of unsaturation. CYRS-myristic acid and CYRS-palmitic acid showed higher complexing index (CI) and relative crystallinity (RC); CYRS-myristic acid and CYRS-oleic acid exhibited lower estimated glycemic index (eGI). Chain lengths of FAs showed significantly positive correlations with CI and contact angle (CA), and yet, unsaturation degree of FAs was negative correlated with both CI and CA. The eGI exhibited positive relations with solubility, and negative correlations with CI and RC. Therefore, the results indicated that chain lengths and unsaturation degrees of FAs were key factors for complexation of the CYRS-FA complexes, which influenced the structural, physicochemical and digestive properties. The findings were expected to provide a theoretical foundation for the interactions between starch and lipids in food processing, and elevate the high-tech values of Chinese yam.

Variations in structural and physicochemical properties of lotus seed starch-protein blends under various HHP treatment conditions

The interaction between starch and proteins is a common phenomenon in food processing, which considerably influences food quality. This study investigated the effect of different pressure levels (0.1-600 MPa, 10 min) and holding times (400 MPa, 10-60 min) under high hydrostatic pressure treatment parameters on structures and physicochemical properties of lotus seed starch-protein (LS-LP) blends. Subsequent examination by Fourier transforms infrared spectroscopy and UV-visible absorption spectra revealed stronger interaction between LS and LP with a change in the hydrogen bond content. Scanning Electron Microscope results showed that LS and LP existed in a blended form. X-ray diffraction revealed that the crystallinity decreased with an increase in treatment intensity of LS-LP blends. The improved water absorption capacity of LS-LP blends (<400 MPa) enhanced viscosity, swelling, and solubility power. This study presents a novel practical method of preparing LS-LP blends and provides insights into physicochemical properties to facilitate processing of LS-based food.

Impact of Ultrasonic-Assisted Preparation of Water Caltrop Starch-Lipid Complex: Structural and Physicochemical Properties

This study investigates the effect of ultrasonic-assisted preparation on the structural and physicochemical properties of water caltrop starch-palmitic acid complexes as a function of ultrasound intensity and treatment time. All samples exhibited the characteristic birefringence of starch-lipid complexes under the polarized microscope, and flake-like and irregular structure under scanning electron microscope (SEM), indicating the formation of complexes through ultrasonic-assisted preparation. X-ray diffraction pattern further confirmed the transition from the original A-type structure for native starch to V-type structure for starch-lipid complexes, and the relative crystallinity of starch-lipid complexes increased as the ultrasound intensity and treatment time increased. Attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR) analysis indicated a decreasing trend in absorbance ratio at wavenumber of 1022 cm-1/995 cm-1, suggesting that the increase in the complex promoted the self-assembly within the short-range ordered structure, leading to the formation of bonds between the complexes. However, rapid-visco analysis (RVA) demonstrated that the viscosity generally decreased as the ultrasound intensity and treatment time increased, possibly due to the reduction in molecular weight by ultrasound. Differential scanning calorimetric (DSC) analysis revealed that the control starch-lipid complex without ultrasound treatment (US-0-0) exhibited two distinct endothermic peaks above 90 °C, representing Type I (95-105 °C) and Type II (110-120 °C) V-type complexes. However, ultrasound-treated samples showed only one peak around 95-105 °C and increased enthalpy (∆H), which was likely due to the breakdown of amylose and amylopectin, leading to more complex formation with palmitic acid, while the resulting shorter chains in the ultrasound-modified sample favor the formation of Type I complexes.

Effect of legume proteins on the structure and digestibility of wheat starch-lauric acid complexes

The effect of legume proteins (soy protein (SP), chickpea protein (CP) and peanut protein (PP)) on the properties of wheat starch-lauric acid (WS-LA) system and its intrinsic mechanism were investigated. RVA, digestion experiment and TGA results showed that legume proteins prompted the viscosity peak formation during cooling stage and increased anti-digestion and thermal stability of WS-LA system. FT-IR, Raman, XRD and 13C NMR results indicated that legume proteins improved the long-range and short-range ordering degree and single-helix structure of WS-LA system. SP had greater influence on the properties of WS-LA system than that of CP and PP. Proteins with high solubility, emulsifying properties and β-sheet content were conducive to starch-based complexes formation. Molecular dynamics simulation results indicated that major forces for WS-LA-SP formation were hydrogen bonding and van der Waals forces. This study offered crucial information on starch-fatty acid-protein complexes formation for proteins selection in starch-based products development.

Palmitic acid-mediated modulation of crystallization dynamics in amylose microparticle formation: From spherical to macaron and disc shapes

Here, we investigated the complexation of short chain amylose (SCAs) and palmitic acid (PA), serving as polymeric building blocks that alter the selectivity and directionality of particle growth. This alteration affects the shape anisotropy of the particles, broadening their applications due to the increased surface area. By modifying the concentration of PA, we were able to make spherical, macaron, and disc-shaped particles, demonstrating that PA acts as a structure-directing agent. We further illustrated the lateral and longitudinal stacking kinetics between PA-SCA inclusion complexes during self-assembly, leading to anisotropy. Transmission electron microscope (TEM) and scanning electron microscope (SEM) revealed the structural difference between the initial and final morphologies of palmitic acid-short chain amylose particles (PA-SCAPs) compared to those of short-chain amylose particle (SCAPs). The presence of PA-SCA inclusion complex in the anisotropic particles was confirmed using nuclear magnetic resonance (NMR) and powder x-ray diffraction (XRD) analysis.

Effect of electron beam irradiation pretreatment on the structural, physicochemical properties of potato starch-fatty acid complexes and the proliferation of Bifidobacterium adolescentis

The effects of different electron beam irradiation doses (5 KGy, 10 KGy, 20 KGy) on the complexation of potato starch with four saturated fatty acids with different chain lengths, i.e., lauric acid (LA), myristic acid (MA), palmitic acid (PA), and stearic acid (SA), were investigated, including structural properties, physicochemical properties, digestive properties, and the effect of Bifidobacteria proliferation. The complexing index increased significantly with increasing irradiation dose and showed the following order: 20 KGy > 10 KGy > 5 KGy > native starch. At irradiation dose of 20 KGy, PA (88.75 %) showed the highest complexing index, followed by MA (87.40 %), SA (82.95 %) and LA (72.33 %). The results of microstructure, relative crystallinity, gelatinization enthalpy, contact angle, and resistant starch content in starch-fatty acid complexes were consistent with the complexing index. In vitro digestion indicated that at irradiation dose of 20 KGy, the addition of PA yielded the highest content of resistant starch (50.35 %), followed by MA (49.25 %), SA (47.05 %) and LA (44.72 %). The four complexes were eventually assessed for their effects on Bifidobacteria's proliferation, with PA exerting the strongest proliferative effects, followed by MA, SA and LA. Overall, electron beam irradiation exhibited good application prospects in the field of starchy food processing and functional foods development.

The structural and digestive properties of indica rice starch-fatty acid complexes

The structural and digestive properties of indica rice starch-fatty acid complexes and the effects of lipoxygenase on the structural and digestive properties of the complexes were examined in this study. The complexes were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy and Raman spectroscopy. The results showed that indica rice starch had the highest molecular chain order and the highest crystallinity, and the crystallization disappeared after gelatinization, and the formation of indica rice starch-fatty acid complexes promoted the transformation of starch crystal structure from A-type to V-type. Lipoxygenase reduced the regularity of starch molecular crystal structure in the complexes, while enzyme protein improved the order of starch molecular structure in the complexes. The regularity of starch crystal structure in the complexes could improve with the increase of composite temperature and the increase of fatty acid unsaturation. In vitro digestibility and in vitro digestion kinetics showed that the formation of indica rice starch-fatty acid complexes reduced the digestibility of indica rice starch to a certain extent. The RDS content of indica rice starch was 66.42 ± 0.39 %, and lipoxygenase reduced the reduction of rapidly digested starch content during complexes digestion, while enzyme protein increased the content of resistant starch.

Preparation, structure, and in-vitro hypoglycemic potential of debranched millet starch-fatty acid composite resistant starch

Currently, the preparation methods and basic physicochemical properties of starch-FA complexes have been widely studied; however, no in-depth research on the regulatory mechanism of the digestive properties of debranched starch-unsaturated FA complexes has been conducted. Therefore, six fatty acids with different carbon chains and different degrees of unsaturation were complexed with de-branched millet starch in this research, using the microwave method. Microwave millet starch-linoleic acid complex (MPS-LOA) had the highest resistant starch (RS) content, and the structure and physicochemical properties of MPS-LOA were determined using various molecular techniques. The results indicate that MPS-LOA had a resistant starch (RS) content of 40.35% and the most notable fluorescence. The characteristic UV peaks of MPS-LOA were blue-shifted, and new IR peaks appeared. The crystalline structure changed to V-type crystals, the crystallinity increased, and the molecular weight decreased. The enthalpy and coagulability of MPS-LOA increased, and the swelling force decreased. Additionally, MPS-LOA showed enhanced α-glucosidase and α-amylase inhibition, and in-vitro hydrolysis kinetics analysis of MPS-LOA showed a hydrolysis index of 53.8 and an extended glycemic index (eGI)I of 54.6, indicating a low eGI food suitable for consumption by people with type II diabetes. These results provide a theoretical basis for the preparation of amylopectin- and starch-based foods with an anti-enzyme structure and a low glycemic index (GI).

Impacts of fatty acid type on binding state, fine structure, and in vitro digestion of debranched starch-fatty acid complexes with different debranching degrees

This study aimed to investigate the effects of fatty acid (FA) type on the binding state, fine structure, and digestibility of debranched maize starch (DMS)-FA complexes with different enzymatic debranching degrees. Maize starch was hydrolyzed by pullulanase for 1 h (DMS1h) and 6 h (DMS6h) and then complexed with seven types of FAs with varying chain lengths and unsaturation degrees, respectively. All the DMS-FA complexes showed V_6III-type and B-type crystals. Complex formation greatly increased the relative crystallinity of DMS, but significantly decreased its order degree of short-range structure (p < 0.05). Compared with unsaturated FAs, saturated FAs possessed stronger intermolecular interactions with DMS. DMS6h-FA complexes exhibited a markedly higher complexing degree (p < 0.05) than the corresponding DMS1h-FA complexes. The FA molecules in DMS1h-FA complexes were primarily physically trapped outside the amylose helices, whereas those in DMS6h-FA complexes were mainly weakly bound to the cavity of amylose helices. The resistant starch (RS) content and relative crystallinity of DMS-FA complexes considerably increased with increasing FA chain length. Furthermore, the highest RS content (38.90 %) and relative crystallinity (24.23 %) were observed in DMS6h-FA complexes. The FA unsaturation degree induced little effect on the RS content and long-range structural order of the complexes.

A review of green methods used in starch-polyphenol interactions: physicochemical and digestion aspects

The interactions of starch with lipids, proteins, and other major food components during food processing are inevitable. These interactions could result in the formation of V-type or non-V-type complexes of starch. The starch-lipid complexes have been intensively studied for over five decades, however, the complexes of starch and polyphenols are relatively less studied and are the subject of recent interest. The interactions of starch with polyphenols can affect the physicochemical properties and its digestibility. The literature has highlighted several green methods such as ultrasound, microwave, high pressure, extrusion, ball-milling, cold plasma etc., to assist interactions of starch with polyphenols. However, comprehensive information on green methods to induce starch-polyphenol interactions is still scarce. Therefore, in light of the importance and potential of starch-polyphenol complexes in developing functional foods with low digestion, this review has summarized the novel green methods employed in interactions of starch with flavonoids, phenolic acids and tannins. It has been speculated that flavonoids, phenolic acids, and tannins, among other types of polyphenols, may have anti-digestive activities and are also revealed for their interaction with starch to form either an inclusion or non-inclusion complex. Further information on the effects of these interactions on physicochemical parameters to understand the chemistry and structure of the complexes is also provided.

Structural Properties of Lotus Seed Starch Nanocrystals Prepared Using Ultrasonic-Assisted Acid Hydrolysis

This study provides a novel method of preparing lotus seed starch nanocrystals (LS-SNCs) using acid hydrolysis combined with ultrasonic-assisted acid hydrolysis (U-LS-SNCs) and evaluates the structural characteristics of starch nanocrystals using scanning electron microscopy; analysis of particle size, molecular weight, and X-ray diffraction patterns; and FT-IR spectroscopy. The results showed that the preparation time of U-LS-SNCs could be reduced to 2 days less than that for LS-SNCs. The smallest particle size and molecular weight were obtained after a 30 min treatment with 200 W of ultrasonic power and 5 days of acid hydrolysis. The particle size was 147 nm, the weight-average molecular weight was 3.42 × 10⁴ Da, and the number-average molecular weight was 1.59 × 10⁴ Da. When the applied ultrasonic power was 150 W for 30 min and acid hydrolysis was applied for 3 days, the highest relative crystallinity of the starch nanocrystals was 52.8%. The modified nanocrystals can be more widely used in various applications such as food-packaging materials, fillers, pharmaceuticals, etc.

Increasing the pressure during high pressure homogenization regulates the starch digestion of the resulting pea starch-gallic acid complexes

The pea starch-gallic acid (PS-GA) complexes were prepared using high pressure homogenization (HPH), then the effect and underlying mechanism of pressure on multi-scale structure and digestibility of complexes were investigated. Results showed that HPH promoted the formation of PS-GA complexes, reaching the maximum complex index of 7.74 % at the pressure of 90 MPa, and the main driving force were hydrophobic interactions and hydrogen bonding. The interaction between PS and GA facilitated the formation of surface reticular structures to encapsulate gallic acid molecules, further entangled into bigger size aggregates. The enhancement of rearrangement and aggregation of starch chains during HPH developed a dense hierarchical structure of PS-GA complexes, including short-range ordered structure, V-type crystal structure, lamellar and fractal structure, thus increasing gelatinization temperature. The digestibility of PS-GA complexes substantially changed in reducing rapidly digestible starch content from 29.67 % to 17.07 %, increasing slowly digestible starch from 53.69 % to 56.25 % and resistant starch from 16.63 % to 26.67 %, respectively. Moreover, the resulting complexes exhibited slower digestion rates compared with native PS. Furthermore, the regulating mechanism of pressure during HPH on starch digestibility was the formation of ordered multi-scale structure and inhibition of GA on digestive enzymes.

Recent advances in structural characterization of biomacromolecules in foods via small-angle X-ray scattering

Small-angle X-ray scattering (SAXS) is a method for examining the solution structure, oligomeric state, conformational changes, and flexibility of biomacromolecules at a scale ranging from a few Angstroms to hundreds of nanometers. Wide time scales ranging from real time (milliseconds) to minutes can be also covered by SAXS. With many advantages, SAXS has been extensively used, it is widely used in the structural characterization of biomacromolecules in food science and technology. However, the application of SAXS in charactering the structure of food biomacromolecules has not been reviewed so far. In the current review, the principle, theoretical calculations and modeling programs are summarized, technical advances in the experimental setups and corresponding applications of in situ capabilities: combination of chromatography, time-resolved, temperature, pressure, flow-through are elaborated. Recent applications of SAXS for monitoring structural properties of biomacromolecules in food including protein, carbohydrate and lipid are also highlighted, and limitations and prospects for developing SAXS based on facility upgraded and artificial intelligence to study the structural properties of biomacromolecules are finally discussed. Future research should focus on extending machine time, simplifying SAXS data treatment, optimizing modeling methods in order to achieve an integrated structural biology based on SAXS as a practical tool for investigating the structure-function relationship of biomacromolecules in food industry.

Influence of different kinds of fatty acids on the behavior, structure and digestibility of high amylose maize starch-fatty acid complexes

BACKGROUND

The formation of starch-lipid complexes is of interest to food processing and human nutrition. Fatty acid (FA) structure is important for the formation and structure of starch-FA complexes. However, there is limited research regarding the complexing behavior between amylose and different kinds of FAs, as well as the relationship between fine structures and digestibility of the formed complexes. This study aimed to investigate the behavior, fine structure, and digestibility of complexes formed between high amylose maize starch (HMS) and FA having various chain lengths and unsaturation degrees.

RESULTS

Complexes containing different FA structures showed V_6III -type crystals. Complexes containing 18-carbon unsaturated FAs displayed significantly higher complexing index (P < 0.05) than other complexes. Complexes containing 12-carbon FAs and 18-carbon FAs with one unsaturation degree showed a higher degree of structural order and resistant starch (RS) content than other complexes. The 12-carbon FAs exhibited a higher binding degree with helical cavity of amylose than other FAs. Additionally, 10-carbon and 18-carbon saturated FAs tended to combine with HMS outside amylose helices more than other FAs. Laser confocal micro-Raman imaging revealed that the physically embedded 10-carbon and 18-carbon saturated FAs showed heterogeneous distribution in complexes, and that the complexed 18-carbon FAs with one unsaturation degree exhibited homogeneous distribution.

CONCLUSION

The behavior, structural order and digestibility of complexes could be regulated by FA structure. The 12-carbon FAs and 18-carbon FAs with one unsaturation degree were more suitable for the production of HMS-FA complexes with higher structural order and RS content than other FAs. © 2022 Society of Chemical Industry.

Starch-lauric acid complex-stabilised Pickering emulsion gels enhance the thermo-oxidative resistance of flaxseed oil

Hydrophobic-modified starch complexes have the potential to form Pickering emulsions and improve the oxidative stability of flaxseed oil. Here, V-type starch-lauric acid complexes (SLACs) were fabricated via solid encapsulation within 0.5-12 h and applied in flaxseed oil Pickering emulsions. Complexing index, X-ray diffraction and differential scanning calorimetry analyses confirmed that the degree of complexation increased with the reaction time. Pickering emulsion gels stabilised by SLACs generated with reaction times of 6 h and 12 h exhibited good storage stability and high yield stress, G' values and apparent viscosity. Confocal laser scanning microscopy and cryo-scanning electron microscopy revealed a gelation mechanism involving increased interface roughness and enhanced droplet-droplet interaction. In comparison to pure flaxseed oil, higher thermo-oxidative resistance was observed at 130 °C, with a markedly longer oxidation induction for emulsions and emulsion gels stabilised by SLACs. Our findings could assist in the design of hydrophobic-modified starch and provide a new paradigm for delaying oil oxidation.

Preparation of starch-based functional food nano-microcapsule delivery system and its controlled release characteristics

Most of the functional substances in food are absorbed in the small intestine, but before entering the small intestine, the strong acid and enzymes in the stomach limit the amount that can reach the small intestine. Therefore, in this paper, to develop a delivery system for functional food ingredients, maintain the biological activity of the ingredients, and deliver them to the target digestive organs, preparation of starch-based functional food nano-microcapsule delivery system and its controlled release characteristics were reviewed. Embedding unstable food active ingredients in starch-based nano-microcapsules can give the core material excellent stability and certain functional effects. Starch-based wall materials refer to a type of natural polymer material that uses starch or its derivatives to coat fat-soluble components with its hydrophobic cavities. The preparation methods of starch-based wall materials mainly include spray drying, extrusion, freeze drying, ultra-high pressure, coagulation, fluidized bed coating, molecular inclusion, chemical, and enzymic methods. The controlled release of functional food can be achieved by preparing starch-based nano-microcapsules to encapsulate the active agents. It has been reported that that compared with traditional embedding agents such as gelatin, acacia gum, and xanthan gum, starch-based functional food nano-microcapsule delivery system had many good properties, including improving antioxidant capacity, bioavailability, probiotics, and concealing bad flavors. From this review, we can learn which method should be chosen to prepare starch-based functional food nano-microcapsule delivery system and understand the mechanism of controlled release.

Multi-scale structures and physicochemical properties of waxy starches from different botanical origins

The multi-scale structures and physicochemical relationships of three different types of waxy starches (maize, tapioca, and potato) were investigated. The maize and tapioca starches exhibited A-type crystalline polymorph compared to potato starch (B-type). The WMS showed higher amorphous content (5.56 %) than other waxy starches. The WTS exhibited a low tendency of retrogradation with its high f_a (DP 6-12) and low f_b3 (DP ≥ 37) proportion of chains. Double helix content of WPS was observed highest with a high pasting viscosity (952.3 BU). Low f_a (DP 6-12) and high f_b3 (DP ≥ 37) chain proportions of the WPS retrograded easily. The compactness of the semi-crystalline aggregation structure influenced the retrogradation properties of waxy starches with a positive correlation. Furthermore, the peak viscosity of pastes was correlated with the proportion of f_b3 (DP ≥ 37) chains, mass fractal dimension, and double helix content. The results provide guidance to design the application of waxy starches in the production of clean-labels.

Structural, physicochemical properties, and digestibility of lotus seed starch-conjugated linoleic acid complexes

This paper describes a new method combining octenyl succinic anhydride (OSA) esterification and high hydrostatic pressure for starch modification, which interacts with conjugated linoleic acid (CLA) to form an octenyl succinic anhydride-lotus seed starch-conjugated linoleic acid (OSA-LS-CLA) complex. This method proves the formation of complex observed by fourier transform infrared spectroscopy and complex index. The stable structure of the complex was derived from increasing molecular weight by introducing macromolecular conjugated linoleic acid and the higher crystallinity than original starch observed by X-ray diffraction. The formation method and changes of complex were observed by scanning electron microscopy and confocal laser scanning microscope. The solubility and swelling power of the complex increases as the temperature increased, significantly at 75 °C. The formation of the OSA-LS-CLA complex significantly reduced the digestion rate of LS, which was 26 % lower than that of LS. These results indicate that the OSA-LS-CLA under high hydrostatic pressure can form a complex with stable structure, which makes up for the deficiency of raw starch to a certain extent. And the formation of this structure can improve the thermal stability of the complex and has strong digestion resistance, which provides a potential direction for further research in reducing starch digestibility.

Resistant structure of extruded starch: Effects of fatty acids with different chain lengths and degree of unsaturation

This study investigated the formation mechanism of enzyme-resistant structures in extruded starch, specifically, fatty acid-starch complexes (FASCs). The effects of fatty acids (FAs) with different carbon-chain lengths (C12-C18) and degrees of unsaturation (C18:0-C18:2) on complex formation were evaluated, with fluorescence microscopy verifying complex formation. The complexed-lipid content and degree of relative crystallinity increased with the carbon-chain length and degree of FA unsaturation. FAs with fewer carbons were more likely to generate stable complexes (e.g., form II, melted at 100-120 °C), while FAs with more carbons tended to produce relatively unstable complexes (e.g., form I, melted at 80-100 °C). After reheating and cooling, a new amylose-lipid complex and an amylose-amylopectin network was formed in the unsaturated FASC samples, which restricted the penetration of enzymes into starch granules. A starch-linoleic acid complex exhibited the highest resistant starch content (15.7%) and lowest predicted glycaemic index (88.4).

Complexation of maltodextrin-based inulin and green tea polyphenols via different ultrasonic pretreatment

Ultrasound has been applied in food processing for various purpose, showing potential to advance the physical and chemical modification of natural compounds. In order to explore the effect of ultrasonic pretreatment on the complexation of inulin and tea polyphenols (TPP), different frequencies (25, 40, 80 kHz) and output power (40, 80, 120 W) were carried out. According to the comparison in particle size distribution and phenolic content of different inulin-TPP complexes, it was indicated that high-intensity ultrasonic (HIU) treatment (25 kHz, 40 W, 10 min) could accelerate the interaction of polysaccharides and polyphenols. Moreover, a series of spectral analysis including UV-Vis, FT-IR and NMR jointly evidenced the formation of hydrogen bond between saccharides and phenols. However, the primary structure of inulin and the polysaccharide skeleton were not altered by the combination. Referring to field emission scanning electron microscopy (FESEM), the morphology of ultrasound treated-complex presented a slight agglomeration in the form of bent sheets, compared to non-treated sample. The inulin-TPP complex also revealed better stability based on thermogravimetric analysis (TGA). Thus, it can be speculated from the identifications that proper ultrasonic treatment is promising to promote the complexation of some food components during processing.

Solid encapsulation of lauric acid into "empty" V-type starch: Structural characteristics and emulsifying properties

Lauric acid was introduced into "Empty" V-type starch using a solid encapsulation method. The structural characteristics and emulsifying properties of the starch-fatty acid complex (SFAC) were explored as a function of the complexing temperature. X-ray diffraction and differential scanning calorimetry confirmed that SFAC was mainly composed of type-I amylose inclusion complexes. Contact angle measurements revealed that the hydrophobic properties of SFAC were closely related to the temperature-regulated complex index. The particle size range of SFAC gradually increased as the complexing temperature increased. The SFAC-stabilized Pickering emulsion at c of 5% and Φ of 40-60% possessed a small droplet size and long-term storage stability for up to 30 days, resulting from the formation of a gel-like network. This study provides new insight into the design of hydrophobic modified starch as a novel and multifunctional emulsifier and is of great help in the development of starch-based Pickering emulsion gels.

Effects of freeze-thaw treatment and pullulanase debranching on the structural properties and digestibility of lotus seed starch-glycerin monostearin complexes

The effects of multiple cycles of freeze-thaw treatment, combined with pullulanase debranching, on the structural properties and digestibility of lotus seed starch-glycerin monostearin complexes were investigated. The formation and melting of ice crystals during freeze-thaw treatment disrupted the crystalline structure of the starch granules, creating pores which facilitated access of pullulanase to the interior of the granules. Pullulanase debranching increased the free amylose content of the starch, which promoted the formation of starch-lipid complexes, which, in turn, increased the proportion of resistant starch and the overall resistance of the starch to digestive enzyme action. These effects increased with the number of freeze-thaw cycles, because more cycles increased both the disruption of the granule structure and the extent of pullulanase debranching. These findings provide a basis for the preparation of functional foods with low glycemic indices, which have strong potential for management of type II diabetes.

Effects of freeze-thaw pretreatment on the structural properties and digestibility of lotus seed starch-glycerin monostearin complexes

To investigate the effects of freeze-thaw cycle pretreatment (in one cycle, frozen samples were reheated to 50 °C and then frozen at -20 °C) on the structural properties and digestibility of lotus seed starch-glycerin monostearin complexes, their complex index, crystal structure, molecular structure, micro-morphology, and digestibility were analyzed. The results showed that an appropriate number of freeze-thaw cycles facilitated the helical assembly of lotus seed starch and glycerin monostearin. Specifically, six cycles of freeze-thaw pretreatment were favorable for forming V_6I-type complexes with high microcrystalline proportion. This contributed to the high stability of crystalline region and order arrangement of molecular structure. Moreover, V_6I-complexes were in the form of lamellar debris in micro-morphology, and their total digestion and digestion rates were lower than those of other samples. These results were of significance for developing slowly digesting lotus seed starch-based food.

The impact of various exogenous type starch on the structural properties and dispersion stability of autoclaved lotus seed starch

In order to investigate the effects of exogenous V-type starch on the structural properties and dispersion stability of lotus seed starch after autoclave treatment, the crystal structure, molecular structure, and dispersion stability were analyzed and discussed, as well as compared with exogenous A-type and B-type starches. Analysis of structural properties indicated that the addition of different crystal nuclei led the crystallization of disordered helices to a specific direction. The B- and V-type starch addition increased the crystallinities of starch and enhanced the ordered arrangement of disordered helices, whereas A-type starch had no significant positive influence on the stability of starch system. The microstructure observation showed that A- and B-type starch addition led to a rough and porous morphology of starch particles; the presence of V-type starch retarded the agglomeration and retrogradation of starch after autoclaving. Analysis of contact angle and dispersion stability revealed that the addition of various exogenous starch increased the contact angle of starch particles in different extent, suggesting the enhancement of hydrophobicity. But B-type starch addition resulted in the poor dispersion stability compared to A-type starch, instead V-type starch addition improved the dispersion stability of starch in aqueous solution, allowing the particles to stay dispersed for 141.12 ± 6.52 min. These results provided a theoretical basis for the effects of exogenous type starch on original starch properties, and revealed the potential of V-type starch as dispersion stabilizer.

Effect of homogenization-pressure-assisted enzymatic hydrolysis on the structural and physicochemical properties of lotus-seed starch nanoparticles

In previous studies, we successfully prepared lotus-seed starch nanoparticles (LS-SNPs) using enzymatic methods. To further improve their performance, we studied the structural, physical and chemical properties of LS-SNPs prepared by high-pressure homogenization (HPH)-assisted enzymatic hydrolysis (EH). HPH treatments at different pressures and frequencies have a significant effect on the particle size and molecular weight of LS-SNPs. Structural analyses showed that LS-SNP and H-LS-SNP both comprised B-type starch crystals. As the homogenization pressure and frequency were increased, the relative crystallinity of H-LS-SNP first increased and then decreased, indicating that HPH treatment affected the double-helix structure of LS-SNPs. The results also show that moderate HPH treatment was beneficial for enzymatic hydrolysis, but when the HPH treatment was further increased, it destroyed the ordered structure of LS-SNPs. Our research showed that H-LS-SNPs with the smallest particle size and the highest crystallinity were obtained under pressure of 150 MPa, a homogenization frequency of five times the original, and a material-to-liquid ratio of 3%. The results indicate that HHP-assisted EH is a suitable method for preparing SNPs. These findings provide new ideas for the preparation of SNPS to meet the needs of food industry.

Structural and physicochemical properties of lotus seed starch nanoparticles prepared using ultrasonic-assisted enzymatic hydrolysis

Lotus seed starch nanoparticles were prepared by ultrasonic (ultrasonic power: 200 W, 600 W, 1000 W; time: 5 min, 15 min, 25 min; liquid ratio (starch: buffer solution): 1%, 3%, 5%) assisted enzymatic hydrolysis (LS-SNPs represent lotus seed starch nanoparticles prepared by enzymatic hydrolysis and U-LS-SNPs represent lotus seed starch nanoparticles prepared by high pressure homogenization-assisted enzymatic hydrolysis). The structure and physicochemical properties of U-LS-SNPs were studied by laser particle size analysis, scanning electron microscope, X-ray diffraction, Raman spectroscopy, nuclear magnetic resonance and gel permeation chromatography system. The results of scanning electron microscopy showed that the surface of U-LS-SNPs was cracked and uneven after ultrasonic-assisted enzymolysis, and there was no significant difference from LS-SNPs. The results of particle size analysis and gel permeation chromatography showed that the particle size of U-LS-SNPs (except 5% treatment group) was smaller than that of LS-SNPs. With the increase of ultrasonic power and time, the weight average molecular gradually decreased. The results of X-ray diffraction and Raman spectroscopy showed that ultrasonic waves first acted on the amorphous region of starch granules. With the increase of ultrasonic power and time, the relative crystallinity of U-LS-SNPs increased first and then decreased. The group (600 W, 15 min, 3%) had the highest relative crystallinity. The results of nuclear magnetic resonance studies showed that the hydrogen bond and double helix structure of starch were destroyed by ultrasound, and the double helix structure strength of U-LS-SNPs was weakened compared with LS-SNPs. In summary, U-LS-SNPs with the small-sized and the highest crystallinity can be prepared under the conditions of ultrasonic power of 600 W, time of 15 min and material-liquid ratio of 3%.

Healthy expectations of high hydrostatic pressure treatment in food processing industry

High hydrostatic pressure processing (HPP) is a non-thermal pasteurization technology which has already been applied in the food industries. Besides maintaining the food safety and quality, HPP also has potential applications in the enhancement of the health benefits of food products. This study examines the current progress of research on the use of HPP in the development of health foods. Through HPP, the nutritional value of food products can be enhanced or retained, including promotes the biosynthesis of γ-aminobutyric acid (GABA) in the food materials, retains immunoglobulin components in dairy products, increases resistant starch content in cereals, and reduces the glycemic index of fruit and vegetable products, which facilitates better control of blood glucose levels and decreases calorie intake. HPP can also be utilized as a hurdle technology in combination with existing processing technologies for the development of low-sodium food products and the maintenance of microbial safety, thereby lowering the risk of triggering cardiovascular disease. Additionally, HPP can be used to enhance the diversity of probiotic food products. Appropriate sporogenous probiotics can be screened and added to various high-pressure processed food products as a certain bacterial count is still retained in the products after HPP. As HPP causes physical damage to the structures of food products, it can also be used as a synergistic extraction technology to enhance the extraction efficiency of functional components, thereby reducing extraction time. By applying HPP in the extraction of functional components from food waste, the production costs of such components can be effectively reduced. This study provides a summary of the mechanisms by which HPP enhances the health benefits of food products and the current progress of relevant research. HPP possesses huge potential in the development of novel health foods and may provide an abundance of benefits to human health in the future.

Physicochemical properties and digestion of the lotus seed starch-green tea polyphenol complex under ultrasound-microwave synergistic interaction

Complex starch is gaining research attention due to its unique physicochemical and functional properties. Lotus seed starch (LS) suspensions (6.7%, w/v) with added green tea polyphenols (GTPs) (10%, w/w) were subjected to ultrasound (200-1000 W)-microwave (150-225 W) (UM) treatment for 15 min. The effects of UM treatment on the physicochemical properties of the LS-GTP system were investigated and exceeded that of microwave or ultrasound alone. The properties (morphology, X-ray diffraction pattern and so on) were affected by GTPs to various extents, depending on ultrasonic power. These influences may be explained by the non-covalent interactions between GTPs and LS. V-type LS-GTP inclusion complex and non-inclusive complex formation were observed. Their morphology and the distribution of GTPs molecules within them were estimated using scanning electron microscopy and confocal laser scanning microscopy. Furthermore, the digestion of LS-GTP complex was investigated by a dynamic in vitro rat stomach-duodenum (DIVRSD) model, lower digestion efficiency of LS has been achieved and the residues showed gradual improvement in morphology. These all experimental results do provide new insight into the complex starch production.