Different effects of pectin and κ-carrageenan on the multiscale structures and in vitro digestibility of extruded rice starch

Effect of various different pretreatment methods on infrared combined hot air impingement drying behavior and physicochemical properties of strawberry slices

In current work, the effect of freezing (F), ultrasound (U), and freeze- ultrasound (FU) pretreatment on infrared combined with hot air impingement drying kinetics, cell ultrastructure, enzyme activity, and physicochemical properties of strawberry slices were explored. Results showed that FU pretreatment enhanced cell membrane permeability via forming micropores, altered water status by transforming bound water into free water and thus promoted moisture diffusivity and decreased drying time by 50% compared to the control group. FU pretreatment also extensively decreased pectin methylesterase enzyme activity and maintained quality. The contents of total phenols, anthocyanins, vitamin C, antioxidant activity, and a* value of dried strawberries pretreated by FU were extensively increased compared to the control group. U and FU pretreatments were beneficial for retaining aromatic components and organic sulfides according to e-nose analyses. The findings indicate that FU is a promising pretreatment technique as it enhances drying process and quality of strawberry slices.

Effect of hydrocolloids on starch digestion: A review

Rapidly digestible starch can increase postprandial blood sugar rapidly, which can be overcome by hydrocolloids. The paper aims to review the effect of hydrocolloids on starch digestion. Hydrocolloids used to reduce starch digestibility are mostly polysaccharides like xanthan gum, pectin, β-glucan, and konjac glucomannan. Their effectiveness is related to their source and structure, mixing mode of hydrocolloid/starch, physical treatment, and starch processing. The mechanisms of hydrocolloid action include increased system viscosity, inhibition of enzymatic activity, and reduced starch accessibility to enzymes. Reduced starch accessibility to enzymes involves physical barrier and structural orderliness. In the future, physical treatments and intensity used for stabilizing hydrocolloid/starch complex, risks associated with different doses of hydrocolloids, and the development of related clinical trials should be focused on. Besides, investigating the effect of hydrocolloids on starch should be conducted in the context of practical commercial applications rather than limited to the laboratory level.

Synergistic modification of hot-melt extrusion and nobiletin on the multi-scale structures, interactions, thermal properties, and in vitro digestibility of rice starch

Background

Rice starch has high digestibility due to its large carbohydrate content. Synergistic modification of hot-melt extrusion (HME) and additives such as flavonoids, hydrocolloids, proteins, lipids, and other additives has the tendency to retard the rate of starch hydrolysis. Hence, the current investigation aimed to study the combined effect of the HME-assisted addition of nobiletin (NOB, 0, 2, 4, and 6%) on the multi-scale structures, interactions, thermal, and digestibility characteristics of rice starch.

Methods

The study employed density functional theory calculations and an infrared second derivative of an Fourier-transform infrared (FTIR) spectrometer to analyze the interactions between NOB and starch. The physicochemical properties of the starch extrudates were characterized by FTIR, 13C nuclear magnetic resonance, X-ray diffraction, and differential scanning calorimetry, while the digestibility was evaluated using an in vitro digestion model.

Results

HME was found to disrupt the crystalline structure, helix structure, short-ordered structure, and thermal properties of starch. The interaction between NOB and starch involved hydrophobic interactions and hydrogen bonds, effectively preventing the molecular chains of starch from interacting with each other and disrupting their double helix structure. The addition of NOB led to the formation of a highly single-helical V-type crystalline structure, along with the formation of ordered structural domains. Consequently, the combined treatment significantly enhanced the ordered structure and thermal stability of starch, thus effectively leading to an increase in resistant starch and slowly digestion starch.

Discussion

The study underscores that synergistic modification of HME and NOB holds promise for enhancing both the nutritional value and functional properties of rice starch. These findings offer valuable insights for developing high-quality rice starch products with broader applications.

Effect of atmospheric pressure plasma jet on the structure and physicochemical properties of wheat starch

The effect of atmospheric pressure plasma jet (APPJ) with different discharge power (0, 400, 600, and 800 W) on the structure and physicochemical properties of wheat starch were evaluated in this study. After APPJ treatments, significant declines in peak viscosity, breakdown viscosity, and final viscosity of wheat starch pasting parameters were observed with increase of plasma treatment power. Being treated with discharge power of 800 W, the PV and BD value of wheat starch paste significantly dropped to 2,578 and 331 cP, respectively. Apparently, APPJ could raise the solubility of wheat starch, while reduce the swelling capacity, and also lower the G' and G″ value of wheat starch gel. Roughness and apparent scratch was observed on the surface of the treated wheat starch granules. Although APPJ treatment did not alter wheat starch's crystallization type, it abated the relative crystallinity. APPJ treatment might be useful in producing modified wheat starch with lower viscosity and higher solubility.

Advancements in enhancing resistant starch type 3 (RS3) content in starchy food and its impact on gut microbiota: A review

Resistant starch type 3 (RS3), often found in cooked starchy food, has various health benefits due to its indigestible properties and physiological functions such as promoting the abundance of gut beneficial microbial flora and inhibiting the growth of intestinal pathogenic bacteria. However, it is challenging to develop starchy food with high RS3 content. This review aims to provide a detailed overview of current advancements to enhance RS3 content in starchy food and its effects of RS3 on gut microbiota. These approaches include breeding high-amylose cereals through gene editing techniques, processing, enzyme treatments, storage, formation of RS3 nanoparticles, and the incorporation of bioactive compounds. The mechanisms, specific conditions, advantages, and disadvantages associated with each approach and the potential effects of RS3 prepared by different methods on gut microbiota are summarized. In conclusion, this review contains important information that aims to provide guidelines for developing an efficient RS3 preparation process and promote the consumption of RS3-enriched starchy foods to improve overall health outcomes.

Exploring the relationship between nutritional properties and structure of chestnut resistant starch constructed by extrusion with starch-proanthocyanidins interactions

Driven by the high economic value of chestnut, creating chestnut-based food with nutritional functions has become a hot spot in food industry. In this study, effect of hot-extrusion treatment (HEX) with starch-proanthocyanidins (PR) interactions (HEX-PR) on chestnut starch (CS) nutritional properties was evaluated from the perspective of structural changes. Results showed that HEX-PR promoted the formation of ordered structure of CS containing single helix, V-type crystalline structure, and starch aggregates, thus increasing the resistant starch (RS) content from 3.25 % to 12.35 %. For the nutritional evaluation, the α-amylase inhibitory activity, antioxidant activity and antiglycation activity of HEX-PR treated CS (HEX-PRS) were enhanced, and the enhancing effect became stronger as PR concentration rose. In addition, HEX-PRS increased the level of short-chain fatty acids (SCFAs), especially propionate, and meanwhile enriched beneficial intestinal bacteria especially the Bifidobacterium. Notably, correction analysis showed that the microbial community was closely related to the α-amylase inhibitory activity, antioxidant activity and antiglycation activity. Overall, this study provided an approach for improving the nutritional functions of starch, and could offer guidance for further investigations to improve the nutritional quality of chestnut starch-based foods.

Inhibition mechanism of rice glutelin on extruded starch digestion: From the structural properties of starch and enzyme activity

To increase the anti-digestion ability of extruded rice starch (ERS), the influence of rice glutelin (RG) on digestive and structural characteristics of ERS were investigated. The resistant starch content increased from 4.49 % to 18.08 % as the RG content increased, while the digestion rate and digestion velocity constant were reduced by the incorporation of RG. Morphological observations showed that ERS was adhered and encapsulated by RG, and the specific area of starch granules were decreased after the addition of RG. The results of XRD and FTIR suggested that the long-range and short-range orders of ERS were improved due to the complexation with RG. The thickness of crystalline of ERS was increased while its amorphous region thickness was reduced by the supplementation with RG. The 1H NMR and 13C NMR data revealed that the branching degree and double helix content of ERS was increased by 46.24 % and 52.67 % when RG content reached to 12 %. Additionally, the addition of RG altered the molecular weight and chain length distribution of ERS. The α-amylase activity and glucoamylase activity was inhibited by RG. These results could provide a valuable basis for the application of RG in extruded rice starchy foods with lower glycemic index.

Polyphenol-fortified extruded sweet potato starch vermicelli: Slow-releasing polyphenols is the main factor that reduces the starch digestibility

To investigate the digestive behavior of extruded starch-polyphenols system, extruded sweet potato starch vermicelli (ESPSV) was used as a model. The multi-scale structure, starch digestibility, polyphenol release, digestive enzyme activity during digestion and their correlation of ESPSV supplemented with matcha (MT), green tea extract (GTE), tea polyphenols (TP) and epigallocatechin gallate (EGCG) (at 1% polyphenol level) were discussed. Results showed that tea products in whatever form could retard starch digestion, with EGCG working best. The predicted glycemic index (pGI) of ESPSV was decreased from 82.50 to 65.46 after adding EGCG. Starch formed larger molecular aggregates with tea products under extrusion, showing a "B + V" type pattern. The order of V-type crystals content was EGCG + ESPSV (1.41) > TP + ESPSV (1.50) > GTE + ESPSV (1.88) > MT + ESPSV (2.62) > ESPSV (3.20). Under external pressure, EGCG, as tea monomer, was more likely to enter the spiral cavity of amylose and form V-type inclusion complex. Notably, polyphenols released during digestion could still reduce digestive enzyme activity, with a 15.53% decrease in EGCG + ESPSV compared to ESPSV. This was verified by correlation analysis, where RDS content (0.961, p < 0.01) and pGI (0.966, p < 0.01) were highly significantly correlated with the enzyme activity. Furthermore, tea products did not break or even enhance the quality of ESPSV as the final product.

Characterization, in vitro digestibility and release properties of starch-linoleic acid-sodium alginate composite film

This study aimed to improve the complexing degree, digestibility and controlled release properties of the potato starch (PS)-linoleic acid (LA) complexes by encapsulating PS-LA complexes to sodium alginate (AG) beads. The results revealed that AG had a positive effect on the complexing index, R1047/1022 values, relative crystallinity, enthalpy and morphological structure of PS-LA-AG films, especially for PS-LA-AG film with the PS-LA: AG of 5:1. The in vitro digestion and hydrolysis kinetic analysis indicated that AG addition reduced the digestibility of PS-LA-AG films to a higher slowly digestible starch content and resistant starch content and a lower equilibrium hydrolysis percentage and kinetic constant. Furthermore, in vivo release study of PS-LA-AG films indicated a restrained release in simulated gastrointestinal conditions. Consequently, the results indicated that AG addition significantly improved the inclusion efficiency for the complex formation between PS and LA, which was beneficial for the design of resistant films to entrap and control release of unsaturated fatty.

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.

Extrusion assisted interaction of rice starch with rice protein and fibre: Effect on physicochemical, thermal and in-vitro digestibility characteristics

Rice starch has high digestibility due to its large carbohydrate content. Macromolecular enrichment of starch has the tendency to retard rate of starch hydrolysis. Hence, the current investigation was aimed to check the combined effect of extrusion assisted addition of rice protein (0, 10, 15 and 20 %) and fibre (0, 4, 8 and 12 %) to rice starch on physico-chemical and in-vitro digestibility characteristics of starch extrudates. It was observed from the study that 'a' and 'b' values, pasting temperature and resistant starch of starch blends and extrudates increased with the addition of protein and fibre. However, lightness value, swelling index, pasting properties and relative crystallinity of blends and extrudates decreased with the addition of protein and fibre. Maximum increase in thermal transition temperatures was observed for ESP₃F₃ extrudates due to absorption capacity of protein molecules which led to late onset of gelatinization. Therefore, enrichment of protein and fibre to rice starch during extrusion can be considered as a novel approach to reduce rate of rice starch digestion for catering nutritional requirements of diabetic population.

Understanding effects of glutelin on physicochemical and structural properties of extruded starch and the underlying mechanism

This work studied effects of different amounts of rice glutelin (RG) on physicochemical and structural properties of extruded rice starch (ERS) and explored the underlying mechanism of interaction between rice starch and RG upon extrusion processing. The results showed that the addition of RG altered the pasting properties, improved the viscoelastic, and increased the water mobility of ERS. The weight loss of ERS decreased from 71.40 % to 62.61 %, while the degradation temperature increased from 290.48 °C to 296.25 °C as the RG content increased from 0 % to 12 %. The complex index of extruded starch-glutelin complexes significantly elevated from 10.40 % to 35.81 % when RG content increased from 6 % to 12 %. Fourier-transform infrared spectra confirmed that RG interacted with starch via Maillard reactions, and the binding strength between RG and starch was enhanced at a higher RG content. Furthermore, results of rheological property and chemical interactions demonstrated that hydrogen bonding, hydrophobic, and electrostatic interaction were formed between RG and starch during extrusion. In summary, the obtained results of this study can further enrich the theory of starch-protein interactions and show the possibility of RG applied in the extruded starchy foods.

A review on application of molecular simulation technology in food molecules interaction

Molecular simulation is a new technology to analyze the interaction between molecules. This review mainly summarizes the application of molecular simulation technology in the food industry. This technology has been employed to assess structural changes of biomolecules, the interaction between components, and the mechanism of physical and chemical property alterations. These conclusions provide a deeper understanding of the molecular interaction mechanism in foods, break through the limitations of scientific experiments and avoid blind and time-consuming scientific research. In this paper, the advantages and development trends of molecular simulation technology in the food research field are described. This methodology can be used to contribute to further studies of the mechanism of molecular interactions in food, confirm experimental results and provide new ideas for research in the field of food sciences.

Influence of starch with different degrees and order of gelatinization on the microstructural and mechanical properties of pectin cryogels: A potential pore morphology regulator

The applications of cryogels are defined by their porous morphology as well as mechanical properties. To achieve efficient regulation of porous properties for pectin cryogels, we selected starch as a potential polysaccharide regulator. Pectin/starch composite cryogels with different degrees of gelatinization were formulated, and two ways of starch gelatinization were considered: starch gelatinization occurred before or after pectin crosslinking during forming the hydrogel network. The results showed that high gelatinized starch (73.8 %-100.0 %) rendered pectin cryogels with denser pore morphology and higher mechanical strength. The pore diameter transferred from 160-200 μm to 40-60 μm with the degree of gelatinization, while the total porosity decreased by about 15 % and the specific surface area increased by about 100 m²/g. When starch gelatinization occurred before pectin crosslinking, the hydrogen bond interactions between gelatinized starch and pectin were formed to accelerate the gelation rate of the pectin Ca²⁺-dependent network. When gelatinization occurred after pectin crosslinking, the pre-formed pectin network delayed the breakdown of the starch crystalline structure during gelatinization. The qualitative regulation of the pore morphology in pectin cryogels by incorporating starches with varying degrees of gelatinization was confirmed.

Dietary compounds slow starch enzymatic digestion: A review

Dietary compounds significantly affected starch enzymatic digestion. However, effects of dietary compounds on starch digestion and their underlying mechanisms have been not systematically discussed yet. This review summarized the effects of dietary compounds including cell walls, proteins, lipids, non-starchy polysaccharides, and polyphenols on starch enzymatic digestion. Cell walls, proteins, and non-starchy polysaccharides restricted starch disruption during hydrothermal treatment and the retained ordered structures limited enzymatic binding. Moreover, they encapsulated starch granules and formed physical barriers for enzyme accessibility. Proteins, non-starchy polysaccharides along with lipids and polyphenols interacted with starch and formed ordered assemblies. Furthermore, non-starchy polysaccharides and polyphenols showed robust abilities to reduce activities of α-amylase and α-glucosidase. Accordingly, it can be concluded that dietary compounds lowered starch digestion mainly by three modes: (i) prevented ordered structures from disruption and formed ordered assemblies chaperoned with these dietary compounds; (ii) formed physical barriers and prevented enzymes from accessing/binding to starch; (iii) reduced enzymes activities. Dietary compounds showed great potentials in lowering starch enzymatic digestion, thereby modulating postprandial glucose response to food and preventing or treating type II diabetes disease.

Effects of non-covalent binding of lignans with rice starch driven by high-pressure homogenization on the starch structure and in vitro nutritional characteristics

As a type of phytoestrogen, lignans have attracted attention in recent years for their nutritional functions. To investigate the effects of lignans on the structural and nutritional functions of starch, honokiol (HK) and arctiin (AC) were complexed with rice starch respectively under high-pressure homogenization (UHPH) (UHPHRS/HK and UHPHRS/AC). The results showed that both HK and AC could form inclusive complexes with rice starch via non-covalent bonding (hydrophobic interaction and hydrogen bonds), and these complexes could further form V-type crystals and aggregates, which reduced the starch digestibility as well as endowing them with the ability to retard glucose release and bind sodium cholate. Interestingly, due to its smaller molecular size, HK could induce starch to form a more compact structure than AC, leading to better nutritional functions. When the addition of HK/AC reached 8%, the resistant starch content could reach 26% and 19.8%, respectively. Meanwhile, the glucose dialysis retardation index could increase to 17.2% and 14.8%, respectively, and the sodium cholate-binding capacity could increase to 33.1 mg g^-1 and 21.8 mg g^-1, respectively. These results demonstrated that UHPH with lignans' molecular interaction could be beneficial for controlling the nutritional functions of starch products with the desired digestibility.

Green Tea Extract Enrichment: Mechanical and Physicochemical Properties Improvement of Rice Starch-Pectin Composite Film

The effects of green tea extract (GTE) at varying concentrations (0.000, 0.125, 0.250, 0.500, and 1.000%, w/v) on the properties of rice-starch-pectin (RS-P) blend films were investigated. The results showed that GTE addition enhanced (p < 0.05) the antioxidation properties (i.e., total phenolic content, DPPH radical scavenging activity, and ferric reducing antioxidant power) and thickness of the RS-P composite film. The darker appearance of the RS-T-GTE blend films was obtained in correspondence to the lower L* values. However, the a* and b* values were higher toward red and yellow as GTE increased. Though GTE did not significantly alter the film solubility, the moisture content and the water vapor permeability (WVP) of the resulting films were reduced. In addition, the GTE enrichment diminished the light transmission in the UV-Visible region (200−800 nm) and the transparency of the developed films. The inclusion of GTE also significantly (p < 0.05) lowered the tensile strength (TS) and elongation at break (EAB) of the developed film. The FT-IR spectra revealed the interactions between RS-P films and GTE with no changes in functional groups. The antimicrobial activity against Staphylococcus aureus (TISTR 764) was observed in the RS-P biocomposite film with 1% (w/v) GTE. These results suggested that the RS-P-GTE composite film has considerable potential for application as active food packaging.

How to synchronously slow down starch digestion and retrogradation: A structural analysis study

Digestibility and retrogradation properties of starch are important for the nutrition and quality of starch-based foods. In this study, a new idea on the synchronous delay the starch digestion and retrogradation was proposed, and the regulation mechanism was explored from perspectives of structural evolution using ¹³C NMR, XRD and SAXS techniques as well as the molecular dynamics simulations. Results showed that the chestnut starch treated with hot extrusion and 8% catechins (HE-8% CA)## could reach highest anti-retrogradation rate (AR 76.63%) and lowest rapidly digestible starch content (RDS 64.55%) at day 24. The starch digestion was slowed down by increasing single/double helix, V-type crystallinity and compactness of aggregates, while retrogradation process was suppressed by inhibiting the packing of short-range ordered structure into long-range ordered structure. The hydrogen bonding and van der Waals forces were the main driving force for the interactions between flavonoid polyphenols and starch molecules. Overall, this study is instructive for further investigations on the synchronous modulation of functional properties of starch.

Synergistic effect of extrusion and polyphenol molecular interaction on the short/long-term retrogradation properties of chestnut starch

The retrogradation properties of starch are closely related to the processing quality of starch-based foods. In this study, the synergistic effects of extrusion and the presence of polyphenols on the water distribution, rheological properties and short-term (1 day)/long-term (21 day) retrogradation of chestnut starch paste were investigated. Post extrusion complexation with catechins (CC)/proanthocyanidins (PC), the short- and long-term retrogradation were both inhibited and the anti-retrogradation rates (AR) during 1 and 21 days were as high as 100% and 44.17-69.30%, respectively. Owing to the destruction of starch chains by extrusion and interaction between starch and polyphenol molecules, the approach, entanglement and aggregation tendencies of starch molecules were all inhibited, which decreased the relative crystallinity (RC), flow resistance and storage modulus of starch paste and also increased the water-holding capacity. The starch retrogradation was thus suppressed. These results are beneficial for the development of starch-based products with high quality and lower retrogradation rate.

Modifying the rheological properties, in vitro digestion, and structure of rice starch by extrusion assisted addition with bamboo shoot dietary fiber

This paper investigated the effect of extrusion treatment on the rheological properties, in vitro digestibility, and multi-structure of starch with or without bamboo shoot dietary fiber (BSDF). The viscoelasticity and thixotropy decreased after extrusion treatment, however, they increased after BSDF addition, and decreased with increasing BSDF content. The starch granules became smooth and formed big lumps after extrusion treatment. The dense lumps became loose after the addition of BSDF. Extrusion treatment changed the movement and arrangement of starch chains and thus the relative crystallinity and branching degree decreased by 92.6% and 40.9%, respectively. The disruption of starch further increased rapid digestion starch (RDS) content by 10%. The decreased disruption of starch granules and increased entanglement between BSDF and starch decreased the RDS content. The addition of BSDF is a novelty method to enhance the nutritional properties and control the physicochemical properties of extruded starchy foods.

Enhancing the functional properties of rice starch through biopolymer blending for industrial applications: A review

Rice starch has been used in various agri-food products due to its hypoallergenic properties. However, rice starch has poor solubility, lower resistant starch content with reduced retrogradation and poor functional properties. Hence, its industrial applications are rather limited. The lack of comprehensive information and a holistic understanding of the interaction between rice starch and endo/exogenous constituents to improve physico-chemical properties is a prerequisite in designing industrial products with enhanced functional attributes. In this comprehensive review, we highlight the potentials of physically mixing of biopolymers in upgrading the functional characteristics of rice starch as a raw material for industrial applications. Specifically, this review tackles rice starch modifications by adding natural/synthetic polymers and plasticizers, leading to functional blends or composites in developing sustainable packaging materials, pharma- and nutraceutical products. Moreover, a brief discussion on rice starch chemical and genetic modifications to alter starch quality for the deployment of rice starch industrial application is also highlighted.