Structural characterization of resistant starch isolated from Laird lentils (Lens culinaris) seeds subjected to different processing treatments

Effects of water-soluble protein of turtle shell on the quality and in vitro digestibility of rice noodles

Turtle shell, as a nourishing product with high nutritional value, offers significant potential as a functional food ingredient. The underlying mechanism by which the turtle shell extract (TSE) 's water-soluble protein affected the quality and digestibility of rice noodles was explored through studying the starch gelatinization, microstructure, and protein interaction forces. Adding 1.0 % to 2.0 % TSE improved the edible quality of rice noodles, including their sensory attributes, structural integrity, hardness, viscosity, and cooking characteristics. At 5 % TSE, the peak viscosity, setback, and enthalpy values decreased by 26.43 %, 19.09 %, and 20.00 %, respectively. Additionally, TSE's protein improved the ordered structure of the starch, in which hydrogen bonds played a key role. TSE's water-soluble protein enhanced the physical barrier that binds protein to starch, primarily through increased hydrogen, disulfide bonding, and decreased hydrophobic interactions. TSE also lowered in vitro starch digestibility, reducing the final hydrolysis from 85.88 % to 72.66 %. Overall, adding 1.0 %-2.0 % TSE enhanced rice noodles edible quality and digestibility by the interaction between protein and starch, or the barrier effect of protein, supporting its potential in improving starchy foods and developing low glycemic index products.

Investigation of the physicochemical factors affecting the in vitro digestion and glycemic indices of indigenous indica rice cultivars

Rice (Oryza sativa) is a vital food crop and staple diet for most of the world's population. Poor dietary choices have had a significant role in the development of type-2 diabetes in the population that relies on rice and rice-starch-based foods. Hence, our study investigated the in vitro digestion and glycemic indices of certain indigenous rice cultivars and the factors influencing these indices. Cooking properties of rice cultivars were estimated. Further, biochemical investgations such as amylose content, resistant starch content were estimated using iodine-blue complex method and megazyme kit respectively. The in vitro glycemic index was estimated using GOPOD method. The rice cultivars considered in our study were classified into low-, intermediate-, and high-amylose rice varieties. The rice cultivars were subjected to physicochemical characterization by using Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) techniques. FTIR spectral analysis revealed prominent bands at 3550-3200, 2927-2935, 1628-1650, 1420-1330, and 1300-1000 cm-1, which correspond to -OH groups, C=O, C=C, and C-OH stretches, and H-O-H and -CH bending vibrations, confirming the presence of starch, proteins, and lipids. Additionally, the FTIR ratio R(1047/1022) confirmed the ordered structure of the amylopectin. DSC analysis revealed variations in the gelatinization parameters, which signifies variations in the fine amylopectin structures and the degree of branching inside the starch granules. The percentage of resistant starch (RS) ranged from 0.50-2.6%. The swelling power (SP) of the rice flour ranged between 4.1 and 24.85 g/g. Furthermore, most of the rice cultivars are classified as having a high glycemic index (GI) based on the estimated in vitro GI (eGI), which varies from 73.74-90.88. The cooking properties of these materials were also investigated. Because the amylose content is one of the key factors for determining the cooking, eating, and digestibility properties of rice, we investigated the relationships between the amylose content and other biochemical characteristics of rice cultivars. The SP and GI were negatively correlated with the amylose content, whereas the RS had a positive relationship. The findings of our study can be beneficial in illustrating the nutritional profile and factors affecting the digestibility of traditional rice cultivars which will promote their consumption, cultivation, and contributes to future food security.

Modulation of Gut Microbiota by the Complex of Caffeic Acid and Corn Starch

To understand the impact of different types of polyphenol-starch complexes on digestibility and gut microbiota, caffeic acid (CA) and corn starch (CS) complexes were prepared by coheating and high-pressure homogenization. The resistant starch content in CS coheated with CA (HCS-CA) and HCS-CA after high-pressure homogenization (HCS-CA-HPH) was 47.75 and 56.65%, respectively. Fourier transform infrared spectroscopy and X-ray diffraction analysis revealed hydrogen bonding in coheated samples and enhanced V-complex formation with high-pressure homogenization. The in vitro-digested complexes were of the B + V type, with higher relative crystallinity and short-range ordering of HCS-CA-HPH. Fermentation of the digested complex with human feces increased the yield of acetate, butyrate, and total short-chain fatty acids (SCFAs), which was more pronounced for HCS-CA-HPH. HCS-CA increased torques-Ruminococcaceae abundance, while HCS-CA-HPH boosted Prevotella, Roseburia, Lachnospiraceae, and Lachnospiraceae-NK4A136. Overall, CA and CS complexes enhanced beneficial bacteria and increased SCFA production.

Evolution of multi-scale structure and microbiota metabolism of lentil resistant starch during the dynamic fermentation in vitro

This study investigated the structural changes of resistant starch (RS) derived from autoclaved lentil starch (ALRS) and untreated lentil starch (ULRS) during in vitro colonic fermentation, as well as their regulatory effects on the composition of the intestinal microbiota. Following in vitro fermentation, both RS samples exhibited a progressive decrease in molecular weight and a gradual increase in double helix/order. Bifidobacterium was more abundant in ULRS during the initial period of fermentation, while ALRS showed higher abundance in the later stage. ALRS demonstrated greater production of short-chain fatty acids (SCFAs) compared to ULRS, likely attributed to its higher structural order and faster fermentation pattern. The distinct surface morphologies of ULRS and ALRS played a crucial role in determining the accessibility of RS substrates for microbial fermentation. These different structural patterns also influenced the shifts in microbial composition in fecal cultures, leading to variations in SCFAs production through anaerobic fermentation.

Improving complexation of puerarin with kudzu starch by various ultrasonic pretreatment: Interaction mechanism analysis

The industrial preparation of kudzu starch (KS) significantly reduces the remaining of flavonoids like puerarin (PU) in the product, weakening its biological activity and making pre-treatments on kudzu crucial. Ultrasonic technique, widely used for modifying biomolecules, can enhance nutrient interactions like those between starch and polyphenols in foods. Thus, a puerarin-kudzu starch (PKS) complex was prepared with the introduction of ultrasonic pretreatment. The results indicated that sonication increased the binding of PU to KS from 0.399 ± 0.01 to 0.609 ± 0.05 mg/g. Particle size analysis and SEM revealed that the particles of the ultrasonic puerarin-kudzu starch complex (UPKS) were larger than those of the untreated complexes. XRD, UV-vis, and FT-IR spectroscopic analyses indicated that hydrogen bonding primarily governs the interaction between PU and KS. Additionally, incorporating PU decreased the starch structure's orderliness, while ultrasonic treatment altered the helical configuration of straight-chain starch, leading to the formation of a new, ordered structure through the creation of new hydrogen bonds. Additionally, gels formed from UPKS exhibited higher viscosity, elasticity, and shear stress, suggesting that ultrasound significantly altered the intermolecular interactions between PKS. In conclusion, the use of ultrasound under optimal conditions has demonstrated its effectiveness in preparing PKS complexes, highlighting its significant potential to produce high value-added kudzu-based products.

Impact of freeze-thaw cycles on the physicochemical properties and structure-function relationship of potato starch with varying granule sizes in frozen dough

Starch, as a critical component of dough, significantly influences quality preservation during the freezing process. In particular, the fine structure of potato (B-type) starch in frozen processing is a subject of considerable interest. This study aims to investigate the intrinsic differences of B-type starch and the impact of freeze-thaw (F/T) treatment on its molecular structure and physicochemical properties. Chain length distribution and X-ray photoelectron spectroscopy were utilized to examine the structural characteristics of natural potato starch with different granule sizes. Furthermore, the fine structure, thermal properties, and rheological properties of the isolated starches after F/T treatment were analyzed. The results indicate that potato starch with smaller particle sizes exhibits higher surface CC and PO content along with a higher proportion of very short chains (DP < 6, 8.17 %) and long B chains (DP > 25, 20.68 %). The study found that after F/T treatment, the surface of small-sized starch granules was initially damaged, exhibiting threads on the surface centered on the umbilical point. Following F/T treatment, both the crystallinity (very large (VL): 24.52-18.36 %; small (S): 17.03-16.69 %) and short-range order (VL: 2.97-2.61; S: 2.71-2.35) of starch particle size decreased. Both the amylose content (20.88-14.57 %) and ΔH (10.15-8.62 J/g) of isolated starch after freeze-thaw-treated dough exhibited a decrease to varying degrees. With the exception of the fifth cycle, small-size starch particles exhibited relatively higher G' and G" values and showed significant changes as a result of F/T treatment, demonstrating high hardness and complex viscosity. Clarifying the physicochemical properties of potato starches with different granule sizes is expected to expand their applications in frozen dough.

Microwave freeze-drying characteristics and crosslinking behavior of wheat starch-laurel acid complex

This article investigates the effect of different microwave powers on the crosslinking behavior and microwave freeze-drying characteristics of wheat starch-lauroyl arginate complex during the microwave freeze-drying process. During microwave freeze-drying, as microwave power increased from 0.1 W/g to 0.9 W/g, the freeze-drying time of WS-LA was reduced by 50 %, while the uniformity of freeze-drying was not affected by its composition. In the research results obtained from DSC, Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), XRD, and SEM analyses, with the microwave power increased from 0.1 W/g to 0.9 W/g, the enthalpy value of the melting peak of the WS-LA (wheat starch-lauric acid) composite decreased from 1.15 J/g to 0.62 J/g. The full width at half maximum (FWHM) value increased from 25.6 to 30.79. The ratio of absorbance at 1022/995 cm-1 increased from 1.0111 to 1.0707. The recrystallization (RC) value decreased from 8.77 % to 0.07 %. Additionally, in the microstructure, the size of WS-LA composite particles decreased accordingly. The above findings indicated that the increase in microwave power during microwave freeze-drying had a negative impact on the formation of the WS-LA complex and the ordering of its structure in the sample.

Effects of amylose and amylopectin fine structure on the thermal, mechanical and hydrophobic properties of starch films

The fine structures of pumpkin, potato, wheat, cassava, and pea starches were determined, followed by an evaluation of how these structures affected the properties of starch films. The structures significantly influenced film properties. Starches with larger molecular weights exhibited greater thermal stability. The tensile strength of starch film was negatively associated with the amylose chain length (r = -0.88, p < 0.05). The chain length distributions of amylose and amylopectin affected the mechanical properties of starch films by influencing structure ordering, supported by the positive correlation between the double helix content and the tensile strength (r = 0.95, p < 0.05). The amylopectin B1, B2, and B3 chains increased film mechanical strength. Conversely, amylopectin A-chains reduced the mechanical strength. The water contact angle was negatively correlated with the B3 chain proportion (r = -0.93, p < 0.05). The pumpkin starch exhibited the highest tensile strength (14.29 MPa), while the wheat starch film showed the highest water contact angle (112°). This study offers valuable insights into the structure-function relationships of starch films, thereby facilitating the acquisition of starch films with enhanced strength and stability through screening or designing starch structures. Consequently, this will expand the application of starch films as packaging materials in various food products.

Isothermal retrogradation preparation of type III resistant starch from extruded-debranched starch: Structure and in vitro digestibility

The extrusion-debranching method is suitable for the industrial production of resistant starch (RS) with high thermal stability. In this study, corn starch treated with extrusion and pullulanase debranching was subjected to different temperatures for different days (1 d, 3 d, and 7 d) and was evaluated by analysing its digestion, crystallization and thermal characteristics. Although the generally accepted optimal retrogradation temperature of starch is 4 °C, it was observed that in vitro digestibility was most reduced by retrogradation at 45 °C, with an RS content of up to 60.19 % on day 7. Retrograding at 45 °C formed more perfect and dense crystals with a mass fractal (Dm) of up to 2.68 and C + V type crystalline pattern. The crystalline pattern of samples stored at 80 °C were A + V and the others were B + V. In addition, samples retrograded at lower temperature showed higher thermal stability. While an increase in storage time at a constant temperature can lead to a reduction in the in vitro digestibility of starch, this effect is not as pronounced as that of temperature.

A mechanistic study of chestnut starch retrogradation and its effects on in vitro starch digestion

Starch retrogradation is a mechanism that is associated with the quality of starch-based food products. A thorough understanding of chestnut starch retrogradation behavior plays an important role in maintaining the quality of chestnut foods during processing and storage. In this study, we investigated the effects of storage time on the structural properties and in vitro digestibility of gelatinized chestnut starch by using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and solid-state 13C nuclear magnetic resonance (NMR). The results showed that the long-range crystallinity and short-range molecular order of retrograded chestnut starch first rapidly increased from 3 h to 3 d and then decreased from 3 d to 7 d, followed by a slight increase from 7 d to 14 d with retrogradation. With the extension of storage time at 4 °C, there were generally obvious increases in single and double helical structures, which were stacked into long-term ordered structure, resulting in increased enthalpy changes as detected by differential scanning calorimetry spectroscopy (DSC) and reduction of the digestion rate of retrograded chestnut starch. Overall, this study may provide important implications for manipulating and improving the quality of chestnut foods.

Flow field-flow fractionation coupled with multidetector: A robust approach for the separation and characterization of resistant starch

The unique properties of resistant starch (RS) have made it applicable in the formulation of a broad range of functional foods. The physicochemical properties of RS play a crucial role in its applications. Recently, flow field-flow fractionation (FlFFF) has attracted increasing interest in the separation and characterization of different categories of RS. In this review, an overview of the theory behind FlFFF is introduced, and the controllable factors, including FlFFF channel design, sample separation conditions, and the choice of detector, are discussed in detail. Furthermore, the applications of FlFFF for the separation and characterization of RS at both the granule and molecule levels are critically reviewed. The aim of this review is to equip readers with a fundamental understanding of the theoretical principle of FlFFF and to highlight the potential for expanding the application of RS through the valuable insights gained from FlFFF coupled with multidetector analysis.

Differences and Mechanism of Waxy Corn Starch and Normal Corn Starch in the Preparation of Recrystallized Resistant Starch (RS3)

This study prepared resistant starch (RS) from waxy corn starch and normal corn starch and analyzed the effects of its molecular and microstructural characteristics on RS content. The RS content of waxy corn resistant starch (RS-WCS) was highest at 57.8%, whereas that of normal corn resistant starch (RS-NCS) was 41.46%. The short-chain amylose contents of RS-WCS and RS-NCS were 47.08% and 37.24%, respectively, proportional to their RS content. Additionally, RS content positively correlated with crystallinity, short-range order degree, and degree of polymerization (DP), exceeding 25. Electron microscopic images, before and after enzymolysis, revealed that RS-WCS was hydrolyzed from the surface to the center by pancreatic α-amylase, while RS-NCS underwent simultaneous hydrolysis at the surface and center. These results indicate that the higher RS content in RS-WCS, compared to RS-NCS, is attributable to the synergistic effects of molecular structure and microstructure.

Effects of repeated and continuous dry heat treatments on the physicochemical, structural, and in vitro digestion properties of chickpea starch

The study investigated the impacts of repeated (RDH) and continuous dry heat (CDH) treatments on the physicochemical, structural, and in vitro digestion properties of chickpea starch. The results of SEM and CLSM showed that more fissures and holes appeared on the surface of granules as the treated time of CDH and the circles of RDH increased, both of which made the starch sample much easier to break down by digestive enzymes. Moreover, the fissures and holes of starch granules treated by CDH were more obvious than those of RDH. The XRD and FT-IR results suggested that the crystal type remained C-type, and the relative crystallinity and R1047/1022 of the chickpea starch decreased after dry heat treatments. In addition, a marked decline in the pasting viscosity and gelatinization temperature of chickpea starches was found with dry heat treatments. Moreover, the increased enzyme accessibility of starch was fitted as suggested by the increased RDS content and digestion rate. This study provided basic data for the rational design of chickpea starch-based foods with nutritional functions.

Study of the changes on the physicochemical properties of isolated lentil starch during germination

In this work, the changes in the composition of the flours and in the morphological, structural, thermal, vibrational, rheological, and functional properties of the isolated lentil starch during the germination process were investigated. The fiber, fat, and ash content of the flours decreased and the protein content increased, while the apparent amylose content of the starch granules remained constant. Using scanning electron microscopy (SEM), the starch granules remained intact during germination, and no enzymatic activity of α- and β-amylases was observed. X-ray diffraction shows that the starch has nanocrystals with hexagonal structure which predominate over the nanocrystals with orthorhombic structure and are classified as C-type starch. The most important result is that these nanocrystals do not play an important role during germination. As the germination time progresses, differential scanning calorimetry (DSC) shows a decrease in the gelatinization temperature (Tp) of the starch, ranging from 70.34 ± 0.25 °C for the native lentil starch to values of 67.16 ± 0.37 °C for the starch on the fourth day of germination (ILS4), this transition being related to the solvation of the nanocrystals. On the other hand, the pasting profiles show no significant changes during germination, indicating that no significant changes in starch content occur during germination. Starch degradation is essential for the production of malt for fermented beverages. This fact makes sprouted lentils not a candidate for the short-term fermentation required in the beverage industry.

Effects of two celery fibers on the structural properties and digestibility of glutinous rice starch: A comparative study

The present study focused on the extraction of water-soluble dietary fiber (CSDF) and water-insoluble dietary fiber (CIDF) from celery. It investigated their effects on glutinous rice starch's (GRS) physicochemical, structural, and digestive properties. The results showed that as the addition of the two dietary fibers increased, they compounded with GRS to varying degrees, with the complexing index reaching 69.41 % and 60.81 %, respectively. The rheological results indicated that the two dietary fibers reduced the viscosity of GRS during pasting and inhibited the short-term regrowth of starch. The FTIR and XRD results revealed that the two fibers interacted with GRS through hydrogen bonding, effectively inhibiting starch retrogradation. Furthermore, both fibers increased the pasting temperature of GRS, thus delaying its pasting and exhibiting better thermal stability. Regarding digestibility, the starch gels containing dietary fibers exhibited significantly reduced digestibility, with RS significantly increased by 8.15 % and 8.95 %, respectively. This study provides insights into the interaction between two dietary fibers and GRS during processing. It enriches the theoretical model of dietary fiber-starch interaction and provides a reference for the application development of starch-based functional foods.

Effect of different heat-moisture treatment times on the structure, physicochemical properties and in vitro digestibility of japonica starch

Modified starch was prepared from japonica starch (JS) by heat-moisture treatments (HMT). Under the same moisture content and HMT temperature, the effects of various HMT times on the structural, properties of JS and its in vitro digestibility properties were investigated. The results showed that adhesion occurred between the particles of japonica starch after the HMT, and there were depressions on the surface. The size of the JS particles increased, the short-range ordering and relative crystallinity of the HMT-modified starch increased and gradually decreased, reaching a peak of 36.51 % at 6 h, as the HMT time was extended. The pasting indexes of HMT-modified starch decreased and then increased with the increase of the HMT time; compared with JS, the thermal stability of HMT-modified starch increased while the pasting enthalpy decreased. All the HMT-modified starches were weakly gelatinous systems and pseudoplastic fluids. Following HMT, the amount of resistant starch (RS) and slowly digested starch (SDS) grew initially before declining. The amount of RS in HMT-modified starch peaked at 24.28 % when the HMT time was 6 h. The results of this research can serve as a theoretical foundation for the creation of modified japonica starch and its use in the food industry.

A Comprehensive Study on the Influence of Superheated Steam Treatment on Lipolytic Enzymes, Physicochemical Characteristics, and Volatile Composition of Lightly Milled Rice

Enzyme inactivation is crucial for enhancing the shelf life of lightly milled rice (LMR), yet the impact of diverse superheated steam (SS) treatment conditions on lipolytic enzyme efficiency, physicochemical properties, and volatile profiles of LMR remains unclear. This study investigated varying SS conditions, employing temperatures of 120 °C, 140 °C, and 160 °C and exposure times of 2, 4, 6, and 8 min. The research aimed to discern the influence of these conditions on enzyme activities, physicochemical characteristics, and quality attributes of LMR. Results indicated a significant rise in the inactivation rate with increased treatment temperature or duration, achieving a notable 70% reduction in enzyme activities at 120 °C for 6 min. Prolonged exposure to higher temperatures also induced pronounced fissures on LMR surfaces. Furthermore, intensive SS treatment led to a noteworthy 5.52% reduction in the relative crystallinity of LMR starch. GC/MS analysis revealed a consequential decrease, ranging from 44.7% to 65.7%, in undesirable odor ketones post-SS treatment. These findings underscore the potential of SS treatment in enhancing the commercial attributes of LMR.

Physicochemical properties and molecular mechanisms of different resistant starch subtypes in rice

Resistant starch (RS) can help prevent diabetes and decrease calorie intake and that from plants are the main source of mankind consumption. Rice is many people's staple food and that with higher RS will help health management. A significantly positive correlation exists between apparent amylose content (AAC) of rice and its RS content. In this study, 72 accessions with moderate or high AAC were selected to explore the regulatory mechanisms and physicochemical properties on different proceeding types of rice RS. RS in raw milled rice (RSm), hot cooked rice (RSc), and retrogradation rice (RSr) showed a wide variation and distinct controlling mechanisms. They were co-regulated by Waxy (Wx), soluble starch synthase (SS) IIb and SSI. Besides that, RSm was also regulated by SSIIa and SSIVb, RSc by granule-bound starch synthase (GBSS) II and RSr by GBSSII and Pullulanase (PUL). Moreover, Wx had significant interactions with SSIIa, SSI, SSIIb and SSIVb on RSm, but only the dominant interactions with SSIIb and SSI on RSc and RSr. Wx was the key factor for the formation of RS, especially the RSc and RSr. The genes had the highest expression at 17 days after flowering and were beneficial for RS formation. The longer the chain length of starch, the higher the RS3 content. RSc and RSr were likely to be contained in medium-size starch granules. The findings favor understanding the biosynthesis of different subtypes of RS.

Extraction, purification and characterization of amylose from sago and corn: Morphological, structural and molecular comparison

In the present work, a comprehensive study was carried out to better understand the molecular characteristics of amylose extracted from sago starch, using butanol as the extraction solvent. The sago derived amylose was compared with amylose extracted from corn starch and both characterized through different techniques, i.e. size exclusion chromatography, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, Scanning electron microscopy, Atomic force microscopy and Zeta potential measurements. The purity of the amylose extracted from sago and corn was 99.20 % and 93.46 %, respectively. From XRD results, it was revealed that sago amylose had more crystallinity with high thermal stability compared to corn amylose. Based on Raman spectra, single and double helices formed in both extracted amyloses, but due to their intrinsic differences, the intensities associated with these helices varied for sago and corn amylose. Purified amyloses were shown to have two different forms of spherulite morphology: torus and spherical shapes with varying degrees of roughness. Our findings demonstrated that sago starch is a novel and low-cost source for supplying amylose, a promising polymer for different applications.

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).

Synergistic modification of ultrasound and bamboo leaf flavonoid on the rheological properties, multi-scale structure, and in vitro digestibility of pea starch

In this study, the effect of ultrasonic treatment (UT), bamboo leaf flavonoid (BLF), ultrasonic treatment prior to bamboo leaf flavonoid (UT-BLF), and bamboo leaf flavonoid prior to the ultrasonic treatment (BLF-UT) on the rheological properties, multi-scale structure, and digestibility of pea starch (PS) were investigated. The morphology and crystal structure of starch granules were destroyed by UT, thereby promoting starch retrogradation and digestion. The binding between BLF and starch through hydrophobic interactions and hydrogen bonds inhibited the interaction between starch molecular chains and impaired their double helix structure, thus effectively retarding starch retrogradation. The anti-digestibility of starch was enhanced after synergistic treatment. Compared with single treatment, synergistic treatment increased the ordered structure and gelatinization enthalpy of starch. In comparison with the UT-BLF group, the viscoelastic and thermal stability of BLF-UT group were improved with the increase in ordered structure. This study could provide valuable information for PS modification.

Structure and physicochemical properties of low digestible Euryale ferox Salisb. seed starch

BACKGROUND

Euryale ferox Salisb. is widely grown in China and Southeast Asia as a grain crop and medicinal plant. The composition, morphology, structure, physicochemical properties, thermal properties, and in vitro digestibility of North Euryale ferox seeds starch (NEFS), hybrid Euryale ferox seeds starch (HEFS), and South Euryale ferox seeds starch (SEFS) were studied.

RESULT

Of the varieties that were studied, the amylose content of NEFS (23.03%) was the highest. Starch granules of each variety were smooth, sharp, small, and had an average diameter of 2 μm. All three varieties were A-type crystals with crystallinity ranging from 26.42% to 28.17%. The degree of double helix and the short-range order ranged from 1.9006 to 2.5324 and 1.4294 to 1.6006, respectively. The high proportion of C1 region in NEFS (17.74%) and HEFS (17.66%) were found. Thermodynamic properties in North Euryale ferox seeds included the highest onset temperature (T_o ) (71.43 °C), peak temperature (T_p ) (76.60 °C), conclusion temperature (T_c ) (82.77 °C), enthalpy of gelatinization (ΔH) (12.64 J g^-1 ), and peak viscosity (1514 mPa·s). All three varieties maintained a low level of in vitro digestibility, with the highest resistant starch (RS) content (29.57%), the lowest rapidly digestible starch (RDS) content (27.07%), and the slowest hydrolysis kinetic constant (0.0303) in NEFS.

CONCLUSION

The results revealed that the low digestibility of NEFS was attributable to compact granules, high crystallinity, high degree of order, and strong thermal stability. These digestive, physicochemical, and thermodynamic properties provide information for the future application of Euryale ferox seed starch in the food industry. © 2022 Society of Chemical Industry.

Different multi-scale structural features of oat resistant starch prepared by ultrasound combined enzymatic hydrolysis affect its digestive properties

In this research, oat resistant starch (ORS) was prepared by autoclaving-retrogradation cycle (ORS-A), enzymatic hydrolysis (ORS-B), and ultrasound combined enzymatic hydrolysis (ORS-C). Differences in their structural features, physicochemical properties and digestive properties were studied. Results of particle size distribution, XRD, DSC, FTIR, SEM and in vitro digestion showed that ORS-C was a B + C-crystal, and ORS-C had a larger particle size, the smallest span value, the highest relative crystallinity, the most ordered and stable double helix structure, the roughest surface shape and strongest digestion resistance compared to ORS-A and ORS-B. Correlation analysis revealed that the digestion resistance of ORS-C was strongly positively correlated with RS content, amylose content, relative crystallinity and absorption peak intensity ratio of 1047/1022 cm^-1 (R_1047/1022), and weakly positively correlated with average particle size. These results provided theoretical support for the application of ORS-C with strong digestion resistance prepared by ultrasound combined enzymatic hydrolysis in the low GI food application.

Pickering emulsion: A multi-scale stabilization mechanism based on modified lotus root starch/xanthan gum nanoparticles

New Pickering emulsion stabilizer LS/XG-NPs (Lotus root starch/xanthan gum nanoparticles) was prepared via autoclaving-cooling method followed by combination with XG. The LS/XG-NPs showed uniform and stable particles with particle size <500 nm, PDI <30, and zeta potential 30-40. The autoclaving-cooling treatment completely changed the crystalline form (from A-type to B-type) and structure of starch; hydrogen bonding and electrostatic interactions were proved to be existed between starch and XG in LS/XG-NPs. The addition of XG increased the contact angle of LS/XG-NPs from 58.79° to 85.42°. In the prepared Pickering emulsion, the LS/XG-NPs adsorbed well on the oil droplets surface, forming a three-dimensional gel network with evenly distributed oil droplets. The Pickering emulsion prepared with LS/XG-NPs showed excellent storage stability and auto-oxidation resistance; the EPA + DHA content in the emulsion remained at 92.46 % after 5 d of storage. The results of this study suggest that LS/XG-NPs have the potential to be food-grade Pickering emulsifiers that not only stabilize emulsions but also prevent emulsion oils from oxidizing.

Effects of microwave and conventional heating on physicochemical, digestive, and structural properties of debranched quinoa starch-oleic acid complexes with different water addition

BACKGROUND

A starch-lipid complex is a new type of resistant starch, which is of great importance for the prevention of chronic diseases such as diabetes. Most starch-lipid complexes usually need to be treated by heating to make them suitable for a variety of applications, and starch-based foods are generally not edible without a heat-treatment process. However, the digestion and structural properties of the starch-lipid complex will be changed after heating. In this study, microwave and conventional heating were used to treat debranched quinoa starch-oleic acid complexes (DQS-OA) with different water addition conditions, and the effects of the two methods on the physicochemical, digestive, and structural properties of DQS-OA were compared.

RESULTS

The results of in vitro digestibility showed that the resistant starch content (235.34-269.55 g kg^-1 ) of the conventional heating-treated samples was significantly higher than that the microwave-treated samples (141.51-157.99 g kg^-1 ). Moreover, after microwave treatment, the short-range molecular order and crystalline structure of DQS-OA were destroyed and the particle size became smaller. In contrast, the thermal stability, enthalpy, and crystallinity of the complexes after conventional heating were improved. The ratio at 1047/1022 cm^-1 of complexes has also been increased.

CONCLUSION

This study demonstrated that conventional water-bath heating was better than microwave heating in increasing digestion resistance, improving the short-range and long-range molecular order, and promoting the formation of DQS-OA. With an increase in water addition, the influence of microwave or water-bath treatment on the properties of DQS-OA became greater. © 2022 Society of Chemical Industry.

Study on structural characteristics, physicochemical properties, and in vitro digestibility of Kudzu-resistant starch prepared by different methods

Three different methods, including autoclaving, autoclaving-debranching, and purification, were used to prepare Kudzu-resistant starch (KRS) from Kudzu starch (KS). The physicochemical properties, such as thermodynamic properties, pasting properties, solubility, swelling, and coagulability, as well as the in vitro digestive characteristics of the three kinds of KRS were studied. The results showed that the morphology of starch granules of KRS prepared by autoclave, autoclave enzymatic hydrolysis, and purification methods was changed and the relative crystallinity was significantly decreased compared with the original starch. X-ray diffraction (XRD) showed that KRS exists in the form of C and C+V crystalline form. There was a significant increase in the pasting temperature and a remarkable decrease in the peak viscosity and the expansion degree of the KRS prepared by all three methods. The solubility of the resistant starch (RS) obtained by autoclaving-debranching and that by purification were both increased compared to that of native KS, while the solubility of the RS obtained by autoclaving was decreased. Meanwhile, the retrogradation of the three RS was also improved to varying degrees. The contents of RS in the samples were: P-KRS (71%) > DA-KRS (43%) > A-KRS (42%) > KS (9%). Simulated human in vitro digestion experiments showed that RS has stronger antidigestibility properties than native starch. Among them, the RS prepared by the purification method has stronger antidigestive properties, and it is predicted that it may have a better potential value in regulating blood glucose. These results indicated that the processing properties of KRS, especially the digestibility, are significantly improved and can be used as a new functional food ingredient, which deserves thorough study.

Non-conventional starch from cubio tuber (Tropaeolum tuberosum): Physicochemical, structural, morphological, thermal characterization and the evaluation of its potential as a packaging material

This work aimed to characterize the physicochemical, structural, morphological, and thermal properties of a non-conventional starch obtained from cubio (Tropaeolum tuberosum), as well as to evaluate the potential use of this native Andean tuber in the preparation of biodegradable packaging. The cubio starch (CUS) showed an intermediated apparent amylose content (31.2 %) accompanied by a high CIE whiteness index (90.8). About the morphology and particle size, the CUS exhibited irregular oval and round shapes and a smooth surface with a mean particle diameter of 14.04 ± 0.1 μm. Although it showed good stability regarding pasting properties, the final viscosity was low. Native CUS exhibits a typical B-type diffraction structure, with a relative crystallinity of 16 %. The resistant starch (RS) fraction of the CUS was 94 %, indicating a low susceptibility to enzymatic hydrolysis. The thermal analysis demonstrated that the CUS showed good thermal stability. Additionally, the films prepared using CUS as raw material showed continuous surfaces without porosities, good thermal stability, and high transparency. The results of this work demonstrate the industrial potential of the CUS as it presents characteristics comparable to commercial potato starch.

Pea-Resistant Starch with Different Multi-scale Structural Features Attenuates the Obesity-Related Physiological Changes in High-Fat Diet Mice

The present study compared the modulatory effects of different resistant starches (RSs) isolated from native (NP-RS), acid-hydrolyzed (AHP-RS), and pullulanase debranched (PDP-RS) pea starches on the corresponding in vivo metabolic responses in high fat (HF)-diet-induced obese mice. The biochemical studies on serum lipid profile and antioxidant enzyme activities were supported by histological and gene expression analyses, which suggested a potential therapeutic role for RS in regulating obesity, possibly through the production of short-chain fatty acids and the proliferation of some beneficial colonic bacteria, including Allobaculum, Bifidobacterium, Odoribacter, Clostridium, and Prevotella. Particularly, a more pronounced effect of AHP-RS with a higher proportion of the crystalline region and a more ordered double-helical alignment on improving the hyperlipidemic symptoms in obese mice induced by a HF diet was observed. Our analysis revealed that the RS3 samples seemed to be more effective than RS2 in terms of attenuating obesity in mice that were fed a HF diet.

Optimization of the Sustainable Production of Resistant Starch in Rice Bran and Evaluation of Its Physicochemical and Technological Properties

In this study, the optimization of ultrasound (US) (850 kHz, 120 W) processing parameters (temperature, time, and power) for the enhanced production of resistant starch (RS) in rice bran (RB) matrixes was performed. The effect of US cavitation at different temperatures on the morphology, physicochemical properties, and mechanical performance of RS was evaluated. Ultrasonication at 40−70 °C temperatures affected the chemical structure, reduced the crystallinity of RS from 23.85% to between 18.37 and 4.43%, and increased the mechanical and thermal stability of RS pastes, indicating a higher tendency to retrograde. US treatment significantly (p < 0.05) improved the oil (OAC) and water (WAC) absorption capacities, swelling power (SP), solubility (WS), and reduced the least-gelation concentration (LGC). The mathematical evaluation of the data indicated a significant effect (p < 0.05) of the US parameters on the production of RS. The largest increment of RS (13.46 g/100 g dw) was achieved with US cavitation at 1.8 W/cm2 power, 40.2 °C temperature, and 18 min of processing time. The developed method and technology bring low-temperature US processing of rice milling waste to create a new sustainable food system based on modified rice bran biopolymers.

Effects of Enzymatic Modification and Cross-Linking with Sodium Phytate on the Structure and Physicochemical Properties of Cyperus esculentus Starch

In this study, C. esculentus porous starch (PS) and C. esculentus cross-linked porous starch (CPS) were prepared by enzymatic modification and sodium phytate cross-linking, and their physicochemical and structural properties were determined. The results showed that the adsorption and emulsification capacities of PS were 1.3606 g/g and 22.6 mL/g, respectively, which were significantly higher than 0.5419 g/g and 4.2 mL/g of C. esculentus starch (NS). The retrogradation curves of starch paste showed that the stability of PS was inferior to that of NS. In addition, the results of texture analysis showed that the gel strength of PS was also significantly reduced relative to NS. The PS exhibited a rough surface with pores and low molecular order and crystallinity according to scanning electron microscope (SEM), fourier infrared spectroscopy (FTIR), and X ray diffractometer (XRD) analyses. As compared to PS, CPS still presented a high adsorption capacity of 1.2744 g/g and the steadiness of starch paste was significantly better. XPS demonstrated the occurrence of the cross-linking reaction. Our results show that enzyme modification and dual modification by combining enzymatic treatment with sodium phytate cross-linking can impart different structures and functions to starch, creating reference material for the application of modified starch from C. esculentus.

Anti-hyperlipidemic and ameliorative effects of chickpea starch and resistant starch in mice with high fat diet induced obesity are associated with their multi-scale structural characteristics

Chickpea starches were isolated from both untreated (UC-S) and conventionally cooked seeds (CC-S), and their multi-scale structural characteristics and in vivo physiological effects on controlling hyperlipidemia in high fat diet induced obese mice were compared with their corresponding resistant starch (RS) fractions obtained by an in vitro enzymatic isolation method (UC-RS and CC-RS). The degree of order/degree of double helix in Fourier transform infrared spectroscopy was in the following order: CC-RS > UC-RS > CC-S > UC-S, which was consistent with the trend observed for relative crystallinity and double helix contents monitored by X-ray diffractometer and solid-state ¹³C cross-polarization and magic angle spinning NMR analyses. The influence of different types of chickpea starch and their corresponding resistant starch fractions on regulating the serum lipid profile, antioxidant status, and histopathological changes in liver, colon and cecal tissues, and gene expressions associated with lipid metabolism, gut microbiota, as well as short-chain fatty acid metabolites in mice with high fat diet induced obesity was investigated. The results showed that the chickpea RS diet group exhibited overall better anti-hyperlipidemic and ameliorative effects than those of the starch group, and such effects were most pronounced in the CC-RS intervention group. After a six-week period of administration with chickpea starch and RS diets, mice in the UC-RS and CC-RS groups tended to have relatively significantly higher levels (P < 0.05) of butyric acid in their fecal contents. The 16S rRNA sequencing results revealed that mice fed with CC-RS showed the greatest abundance of Akkermansia and Lactobacillus compared with the other groups.

Beneficial Effect of Kidney Bean Resistant Starch on Hyperlipidemia-Induced Acute Pancreatitis and Related Intestinal Barrier Damage in Rats

Accumulating attention has been focused on resistant starch (RS) due to its blood-lipid-lowering activities. However, reports on the potential bioactivities of RS for preventing hyperlipidemia acute pancreatitis (HLAP) are limited. Therefore, in this study, an acute pancreatitis model was set up by feeding a hyperlipidemia diet to rats, and subsequently evaluating the anti-HLAP effect of RS in kidney beans. The results show that the IL-6, IL-1β, and TNF-α of serum in each RS group were decreased by 18.67-50.00%, 7.92-22.89%, and 8.06-34.04%, respectively, compared with the model group (MOD). In addition, the mRNA expression of tight junction protein ZO-1, occludin, and antibacterial peptides CRAMP and DEFB1 of rats in each RS group increased by 26.43-60.07%, 229.98-279.90%, 75.80-111.20%, and 77.86-109.07%, respectively. The height of the villi in the small intestine and the thickness of the muscle layer of rats were also increased, while the depth of the crypt decreased. The present study indicates that RS relieves intestinal inflammation, inhibits oxidative stress, and prevents related intestinal barrier damage. These results support the supplementation of RS as an effective nutritional intervention for HLAP and associated intestinal injury.

Effects of Hydrothermal and Microwave Dual Treatment and Zein on the Enzymolysis of High Amylose Corn Starch

Resistant starch (RS) type 2-high-amylose corn starch (HACS) was subjected to simultaneous hydrothermal (25% moisture content, 90 °C for 12 h) and microwave (35% moisture content, 40 W/g microwaving for 4 min) treatment and zein (at a zein to treated starch ratio of 1:5, 50 °C for 1 h) to improve its resistance to enzymolysis. Scanning electron microscopy (SEM) highlighted the aggregation and adhesion of the composite. The average particle size of the composite (27.65 μm) was exceeded that of both the HACS (12.52 μm) and the hydrothermal and microwave treated HACS (hydro-micro-HACS) (12.68 μm). The X-ray diffraction results revealed that the hydro-micro-HACS and composite remained B-type, while their crystallinity significantly decreased to 16.98% and 12.11%, respectively. The viscosity of the hydro-micro-HACS and composite at 50 °C was 25.41% and 35.36% lower than that of HACS. The differential scanning calorimetry (DSC) results demonstrated that the composite displayed a new endothermic peak at 95.79 °C, while the weight loss rate and decomposition temperature were 7.61% and 2.39% lower than HACS, respectively. The RS content in HACS, the hydro-micro-HACS, and composite was 47.12%, 57.28%, and 62.74%, respectively. In conclusion, hydrothermal and microwave treatment combined with zein provide an efficient physical strategy to enhance the RS type 2-HACS.

Properties and digestibility of a novel porous starch from lotus seed prepared via synergistic enzymatic treatment

The objective was to investigate the effect of synergistic enzymatic treatment on the properties and digestibility of a novel C-type lotus seed porous starch (LPS). Scanning electron microscopy showed that the densest and most complete pores were formed on the surface of LPS when the concentration of enzymes added was 1.5% (LS-1.5E). With increases in enzyme addition, the oil and water absorption of the porous starch increased and reached maxima at 1.5% of enzyme. Increased in the specific surface area, total pore volume and average pore diameter of LPS were determined by low-temperature nitrogen adsorption, while when the enzymes exceeded 1.5%, there were no significant changes. Compared to lotus seed starch (LS), the particle size of LPS also decreased. With the increases in enzyme addition, LPS exhibited higher relative crystallinity and ordering structure by XRD and FTIR. The results by SAXS confirmed that LPS had higher ordered semi-crystalline lamellar and denser lamellar structure compared to LS. Low-field ¹H NMR spectroscopy indicated that the proportion of bound water in LPS increased, while the proportion of bulk water decreased. Moreover, the degree of hydrolysis of LPS was lower than that of LS, and the content of rapidly digestible starch decreased, while the content of slowly digestible starch and resistant starch increased with the enzyme addition, which was consistent with the structural properties.

Loss factor and moisture diffusivity property estimation of lentil crop during microwave processing

Characterization of loss factor and moisture diffusivity are required to understand materials' precise behavior during microwave processing. However, providing the processing facilities to measure these properties in a real or simulated situation directly can be complicated or unachievable. Hence, this study proposes an alternative procedure for modeling these properties according to their affecting factors including temperature, and moisture content. The basis of this method is to use an algorithm that combines the optimization approach and the numerical solution of the heat and mass transfer governing equations, including boundary conditions. For this aim, the coefficients of estimated models for loss factor and moisture diffusivity were obtained by minimizing the sum square error of the experimentally measured mean surface temperature and moisture content and the predicted values by solving the system of partial differential equations. The suggested models illustrated that during the microwave process, the moisture diffusivity grows arithmetically, and the loss factor generally raises, but transition points were observed in the trend for the samples tempered up to the 50% moisture content. These points have been attributed to the starch gelatinization and confirm how the bio-chemical reaction would have a noticeable effect on this property, determining the microwave energy absorbance. The results of differential scanning calorimetry thermograms and the Fourier transform mid-infrared spectra of flours obtained from microwave processed lentil seeds also confirmed the greatest intensity of starch structure alteration happened for the samples tempered to 50% moisture content by showing the highest shifts in the endothermic peak and lowest degree of order.

Effects of microwave treatments and retrogradation on molecular crystalline structure and in vitro digestibility of debranched mung-bean starches

The objective of this study was to investigate morphology, molecular crystalline structure, and digestibility of debranched mung bean starches with or without microwave treatment and retrogradation at different temperature. The mung bean starch was firstly debranched with pullulanase, and then the debranched starch containing 20% moisture content was treated by microwave irradiation for 3 min with or without further retrograded at +25, +4, or -18 °C for 24 h. All treated starches exhibited the B + V-type crystalline polymorph as determined by the XRD and the ¹³CNMR. The FT-IR results showed that the debranched starches had lower degree of order but higher degree of double helix than those of the native starch. The microwave treatment or further recrystallization of the debranched starch for more 24 h significantly improved crystalline structure of starch granules with higher degree of relative crystallinity, degree of order, and degree of double helices. The resistant starch content of the treated starch was in a range of 39.7-52.8%, significantly higher than that of the native starch (15.6%). As a result, the microwave-assisted debranched starch with further crystallization for 24 h was found to have highly ordered structure of granules, which highly resisted to the enzyme digestion.

Resistant starch type 2 from lotus stem: Ultrasonic effect on physical and nutraceutical properties

Resistant starch type 2 (RS) was isolated from lotus stem using enzymatic digestion method. The isolated RS was subjected to ultrasonication (US) at different sonication power (100-400 W). The US treated and untreated RS samples were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), light microscopy and Fourier transform infrared spectroscopy (FT-IR). DLS revealed that particle size of RS decreased from 12.80 µm to 413.19 nm and zeta potential increased from -12.34 mV to -26.09 mV with the increase in sonication power. SEM revealed smaller, disintegrated and irregular shaped RS particles after ultrasonication. FT-IR showed the decreased the band intensity at 995 cm-1 and 1047 cm-1 signifying that US treatment decreased the crystallinity of RS and increased its amorphous character. The bile acid binding, anti-oxidant and pancreatic lipase inhibition activity of samples also increased significantly (p < 0.05) with the increase in sonication power. Increase in US power however increased the values of hydrolysis from 23.11 ± 1.09 to 36.06 ± 0.13% and gylcemic index from 52.39 ± 0.38 to 59.50 ± 0.11. Overall, the non-thermal process of ultrasonic treatment can be used to change the structural, morphological and nutraceutical profile of lotus stem resistant starch which can have great food and pharamaceutical applications.

New Type of Food Processing Material: The Crystal Structure and Functional Properties of Waxy and Non-Waxy Proso Millet Resistant Starches

Resistant starch (RS) is widely used in the food industry because of its ability to regulate and protect the small intestine, but their distinct effects on the structural and functional properties of waxy and non-waxy proso millet starches are not completely understood. The crystalline structure and physicochemical properties of waxy and non-waxy proso millets' starch samples were analyzed after heat-moisture treatment (HMT). The analysis revealed significant differences between the RS of waxy and non-waxy proso millets. The crystal type of proso millets' starch changed from type A to type B + V. The relative crystallinity of the RS of waxy proso millet was better than that of non-waxy proso millet. The gelatinization temperature and thermal stability of RS significantly increased, and the pasting temperature (PTM) of the RS of waxy proso millet was the highest. The water solubility and swelling power of the RS in proso millet decreased, and the viscoelasticity improved. The correlation between the short-range ordered structure of RS and ΔH, and gelatinization properties has a stronger correlation. This study provides practical information for improving the nutritional benefits of waxy and non-waxy proso millet in food applications.

Rheological behaviors and physicochemical changes of doughs reconstituted from potato starch with different sizes and gluten

The effects of different sizes of potato starch on the rheological and physiochemical properties of model doughs were investigated. Compared with those of model dough prepared from original starch, the strengths of model doughs prepared from fractionated starch were higher, which indicates that fractionated starch can positively influence the properties of doughs. Additionally, the model dough prepared using large size starch granules had higher storage modulus (G'), loss modulus (G''), and composite modulus (|G*|) values compared to those of other types of dough; it also had the highest elasticity, viscosity, and strength. This might be related to its high amylose content (20.28 ± 0.69%) and high 1045 cm^-1/1022 cm^-1 ratio (1.27 ± 0.17). The model dough (S) prepared from starch with small sizes had the highest contents of disulfide bonds (2.91 μmolg^-1), β-turn (33.92 ± 1.17%), and β-sheet (22.57 ± 0.54%); and it also had better network structure and dough stability. Thus, the stability of the S model dough was affected by phosphorus (1194.57 ± 25.32 ppm) and amylopectin (84.19 ± 1.88%) content, and, moreover, by the competition for water. Stability and network structure of dough are relative to the size distribution of starch granules. Finally, a schematic model showing the mechanism of the influence of phosphorus, sulfhydryl, and disulfide bonds in fractionated starch on the rheological properties of dough was developed.