Physicochemical and digestibility characterisation of maize starch–caffeic acid complexes

Structural properties and antioxidant capacity of different aminated starch-phenolic acid conjugates

Different aminated starch (AS) [EEAS (introducing ethylenediamine into starch using cross-linking-etherification-amination method (CEA)), EPAS (introducing o-phenylenediamine using CEA), OEAS (introducing ethylenediamine using cross-linking-oxidation-amination method (COA)), and OPAS (introducing o-phenylenediamine using COA)] were synthesized. The AS-phenolic acids [gallic acid (GA), syringic acid (SA), and vanillic acid (VA)] conjugates were prepared by laccase-catalyzed reaction. The grafting efficiency of EEAS on GA, SA, and VA was 36.59%, 69.71%, and 68.85%, respectively. SA reduced the maximum depolymerization rate of EEAS. The relative crystallinity of EEAS and EPAS grafted phenolic acid increased, and their particles showed severe breakage in appearance. OEAS-phenolic acid conjugates lost its granular structure and behaved as flakes and lumps, while the surface of OPAS-phenolic acid conjugates remained smooth after grafting phenolic acid. GA increased the DPPH· scavenging efficiency of EEAS from 16.12% to 79.92%. The increased antioxidant capacity of the conjugates suggested that AS-phenolic acids conjugates have high potential for applications.

Starch chain-length distributions affect the processing and digestion characteristics of proso millet starch

Starch chain-length distributions play a key role in regulating the processing and digestion characteristics of proso millet starch. Waxy proso millet starch has higher endothermic enthalpy (13.06-16.73 J/g) owing to its higher relative crystallinity (27.83%-32.04%), while nonwaxy proso millet starch has lower peak viscosity (1.0630-1.1930 Pa∙s) and stronger viscoelasticity owing to its higher amylose content (21.72%-24.34%). Non-waxy proso millet starch exhibited two different digestion phases and its resistant starch content (18.37%-20.80%) was higher than waxy proso millet starch. Correlation analysis showed proso millet starch with longer amylopectin B1 chains and more amylopectin B2 chains exhibited excellent thermal ability and retrograde resistance, whereas proso millet starch with shorter and more amylose medium/long-chains not only reduced the digestion rate and increased the resistant starch content but also exhibited stronger viscoelasticity and excellent retrogradation properties. These results could provide more insights into efficient utilization of proso millet starch.

Insights into impact of chlorogenic acid on multi-scale structure and digestive properties of lotus seed starch under autoclaving treatment

The interaction between polyphenols and starch is an important factor affecting the structure and function of starch. Here, the impact of chlorogenic acid on the multi-scale structure and digestive properties of lotus seed starch under autoclaving treatment were evaluated in this study. The results showed that lotus seed starch granules were destroyed under autoclaving treatment, and chlorogenic acid promoted the formation of loose gel structure of lotus seed starch. In particular, the long- and short-range ordered structure of lotus seed starch-chlorogenic acid complexes were reduced compared with lotus seed starch under autoclaving treatment. The relative crystallinity of A-LS-CA complexes decreased from 23.4 % to 20.3 %, the value of R1047/1022 reduced from 0.87 to 0.80, and the proportion of amorphous region increased from 10.26 % to 13.85 %. In addition, thermal stability, storage modulus and loss modulus of lotus seed starch-chlorogenic acid complexes were reduced, indicating that the viscoelasticity of lotus seed starch gel was weakened with the addition of chlorogenic acid. It is remarkable that chlorogenic acid increased the proportion of resistant starch from 58.25 ± 1.43 % to 63.85 ± 0.96 % compared with lotus seed starch under autoclaving treatment. Here, the research results provided a theoretical guidance for the development of functional foods containing lotus seed starch.

Porous corn starch granules as effective host matrices for encapsulation and sustained release of curcumin and resveratrol

Type 2 Diabetes Mellitus (T2DM) is a carbohydrate-rich diet-regulated ailment with carbohydrates digested and absorbed rapidly. Hence, modulating carbohydrate digestion is warranted; to this end, polyphenols from plant sources are handy. However, polyphenols' instability and low bioavailability limit their wholesome use, and thus, encapsulating them into an inexpensive and suitable wall material would be the best strategy. Herein, the potential of porous starch granules is demonstrated. Curcumin and resveratrol were chosen as the test polyphenols due to their proven health benefits, and porous corn starch granules were chosen as the wall material. Porous corn starch granules were prepared through enzymatic modification with 11, 22, and 33 units of amyloglucosidase at three reaction times of 2, 4, and 6 h. The polyphenols were loaded at 100, 200, and 500 mg concentrations in 1 g of starch for 21 days and were characterized through Scanning Electron Microscope (SEM) and Fourier Transform Infrared spectroscopy (FTIR) analyses. The encapsulation efficiency was determined, the rate of starch digestion was calculated through the Englyst test, and polyphenols' in vitro release behavior in gastric and intestinal fluids was measured. Results suggest that 33 enzyme units for a 2 h reaction time were optimal for forming spherical-oval pores on corn starch granules with the maximum encapsulation efficiency of 80.16 % and 88.33 % for curcumin and resveratrol, respectively. The FTIR results suggest the entrapment of polyphenols inside the starch matrix. The inclusion significantly reduced starch digestion and increased the percentage of resistant starch up to 41.11 % and 66.36 % with curcumin and resveratrol, respectively. The in vitro release behavior demonstrated good stability in the simulated gastric fluids and sustained release in simulated intestinal fluids. The encapsulated polyphenols showed a complex Fickian type of diffusion mechanism. Overall, the results suggest that porous corn starch granules could be a potential delivery system for curcumin and resveratrol and will aid in developing novel functional foods to address the T2DM concerns.

Enhancing nutritional and functional properties of rice starch by modification with Matcha extract

The aim of this study is to increase the functionality of rice starch by modifying matcha tea extract and to determine the effect on some physicochemical properties and starch digestibility. According to the data analyzed, treatment with matcha extract was effective in increasing the nutritional value of native rice starch. At the highest level of extract addition, total phenolic and flavonoid content reached 129.54 mg/100 g and 40.16 mg/100 g, respectively, as no phenolic or flavonoid content was detected in control. In addition, the highest DPPH and FRAP values were determined to be 296.62 μmol TE/100 g and 814.89 mg/100 g, respectively, at the highest extract addition level. Treatment with matcha extract significantly reduced the eGI of native rice starch from to 94.61 to 64.63, while resistant starch was increased from 0.90 to 33.43%. According to the physiochemical analysis, there was a positive correlation between the extract ratio and the water-holding capacity of rice starch due to the high hydrophilic capacity of the phenolic compounds. In addition, the solubility and swelling power of starch were increased by treatment with matcha extract, but high temperatures had a negative effect on these physicochemical properties.

Effects of synergistic action on rheological and thermal properties of potato starch complexes co-gelatinized with caffeic acid and squash polysaccharides extracted with water and subcritical water

In order to broaden the application range of squash polysaccharide (WESP/SWESP) and caffeic acid (CAA) and improve the quality of potato starch (PS) products, the effects of WESP/SWESP and CAA on the gelatinization, rheology, thermodynamics, microstructure and in vitro digestion of PS were investigated. Meanwhile, the synergistic effect of WESP/SWESP and CAA on PS was further analyzed. Differently, due to WESP and SWESP had different monosaccharide composition and structure, they had different effects on the system. Pasting properties results showed that the presence of WESP/SWESP and CAA significantly reduced the peak viscosity, trough viscosity, breakdown viscosity and final viscosity of PS, especially under the combined action. In rheological tests, all sample gels belonged to the pseudoplastic fluids and weak gel system (tan δ < 1). Besides, thermodynamic properties revealed that WESP/SWESP and CAA synergistic effect had better retrogradation delay effect. In the ternary system, WESP/SWESP, CAA and PS can form a new network structure and improve the stability of the gel system. In addition, the results of infrared spectroscopy, Raman spectroscopy, x-ray diffraction and scanning electron microscopy exhibited that the ternary system can promote the accumulation and winding of the spiral structure of PS chain, and make the structure of PS gel network more orderly and stable. Furthermore, compared with PS gel, the ternary system had lower RDS and higher SDS and RS content, suggesting that the addition of WESP/SWESP and CAA at the same time was more conducive to reducing the hydrolysis rate of PS. This work revealed the interaction between WESP/SWESP, CAA and PS, which improved the physicochemical and digestive properties of PS. It will provide a theoretical basis for improving the quality of potato starch-related products and developing functional foods.

Physicochemical and digestive properties of corn starch nanoparticles incorporated different polyphenols

The corn starch nanoparticles were prepared by incorporating three kinds of polyphenols, including quercetin, proanthocyanidins and tannin acid. The physicochemical and digestive properties of corn starch nanoparticles were researched. The quercetin showed a higher complexation index than proanthocyanidins and tannin acid when they complexed with corn starch. The mean size of corn starch quercetin, proanthocyanidins and tannin acid were 168.5 nm, 179.1 nm and 188.6 nm, respectively. XRD results indicated that all the corn starch-polyphenols complex showed V-type crystalline structure, the crystallinity of corn starch-quercetin complex was 19.31 %, which showed more formation of amylose-quercetin single helical formed than the other two starch-polyphenol complexes. In vitro digestion revealed that polyphenols could resist digestion and quercetin increased the content of resistant starch from 23.32 % to 35.24 % and polyphenols can form complexes with starch through hydrophobic interactions or hydrogen bonding. This study indicated the hydrophobic polyphenols had a more significant effect on the digestibility of corn starch. And the cell toxicity assessments demonstrated that all nanoparticles were nontoxic and biocompatible.

Effects of Laminaria japonica polysaccharide and coumaric acid on pasting, rheological, retrogradation and structural properties of corn starch

The aim of this study was to investigate the effects of Laminaria japonica polysaccharide (LJP) and coumaric acid (CA) on pasting, rheological, retrogradation and structural properties of corn starch (CS). Rapid viscosity analysis (RVA) revealed that LJP significantly increased the peak viscosity, trough viscosity, final viscosity, and setback viscosity of CS gel (p < 0.05) in a concentration-dependent manner. The addition of LJP and CA simultaneously caused the pasting of CS to need a greater temperature (from 75.53 °C to 78.75 °C), suggesting that LJP and CA made CS pasting more difficult. Dynamic viscoelasticity measurements found that all gels exhibited typical characteristics of weak gel. When compared to CS gel, 4 % LJP increased the viscosity and fluidity of gel and the simultaneous addition of LJP and CA reduced the elasticity. The steady shear results showed that the all gels were pseudoplastic fluids with shear-thinning behavior. In the meanwhile, the addition of LJP and CA enhanced the pseudoplasticity of CS-LJP-CA gel and improved its shear thinning. Furthermore, thermodynamic results showed that 8 % LJP promoted the retrogradation of CS gel and 2.0 % CA delayed the retrogradation of CS gel. Notably, on the 7th day of retrogradation, 2.0 % CA significantly decreased the retrogradation rate of CS-LJP by 19.31 % as compared to CS + 8 % LJP. Microstructure observation revealed that LJP made the honeycomb network structure of CS gel partially collapsed, and the surface of CS-LJP gel developed venation. Nevertheless, the structure of CS-LJP gel was clearly enhanced by adding CA. FT-IR spectra demonstrated that the addition of LJP or CA to CS did not result in the formation of a new distinctive peak in the system, suggesting the absence of a new group. Moreover, LF-NMR findings showed that LJP and CA strengthened the gel structure of CS and enhanced its capacity to retain water. This study not only provided a new insight into using LJP and CA to regulate the gel properties of CS, but also provided scientific strategy for developing starchy foods.

Quantitative prediction of rice starch digestibility using Raman spectroscopy and multivariate calibration analysis

Digestibility is an important characteristic of rice starch. It is affected by the growing environment, such as temperature and soil, so that even in the same genetic cultivar the digestibility of each product will be different. Here, we predicted rice starch digestibility by Raman scattering spectroscopy. A partial least squares (PLS) regression analysis was performed between biochemically quantified digestibility index values and Raman scattering spectra of purified starch from rice samples of different cultivars and growing conditions. The prediction model obtained by analyzing the individual cultivars was able to predict digestibility with a high accuracy, with an R2 of 0.95 and RMSEP of 0.43, whereas a mixture of all cultivars resulted in more than two times worse accuracy. Our finding suggests that the molecular structures affecting digestibility fluctuate depending on the growing environment while maintaining a unique balance regulated by cultivar-specific starch synthesis mechanisms.

Effect of hawthorn polyphenol extracts on the physicochemical properties and digestibility of corn starch

To investigate the effect of hawthorn polyphenols on the physicochemical properties and digestibility of corn starch, different proportions (1%, 2%, 3%, and 4% [w/w]) of hawthorn polyphenol extracts (HPEs) were mixed with corn starch, and their physicochemical properties and digestive properties were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Rapid Visco Analysis, differential scanning calorimetry, and in vitro/in vivo analysis. Results indicated that small V-type crystal starch tended to be formed in the samples, and the addition of HPEs reduced the viscosity, prolonged the gelatinization temperature of corn starch, and increased the proportion of slowly digestible starch and resistant starch of the corn starch, which accounted for 36.32% ± 1.05% and 33.32% ± 4.07%, respectively. Compared with the raw corn starch, the postprandial blood glucose of mice that were administered the hawthorn polyphenols decreased significantly: the blood glucose peak (30 min) decreased from 14.30 ± 1.52 to 11.77 ± 1.21 mmol/L. Our study might provide some basic theoretical support for the application of hawthorn polyphenols in healthy starchy food processing.

Characterization of Various Noncovalent Polyphenol-Starch Complexes and Their Prebiotic Activities during In Vitro Digestion and Fermentation

This study explores the structural characterization of six noncovalent polyphenol-starch complexes and their prebiotic activities during in vitro digestion and fermentation. Ferulic acid, caffeic acid, gallic acid, isoquercetin, astragalin, and hyperin were complexed with sweet potato starch (SPS). The polyphenols exhibited high binding capacity (>70%) with SPS. A partial release of flavonoids from the complexes was observed via in vitro digestion, while the phenolic acids remained tightly bound. Molecular dynamics (MD) simulation revealed that polyphenols altered the spatial configuration of polysaccharides and intramolecular hydrogen bonds formed. Additionally, polyphenol-SPS complexes exerted inhibitory effects on starch digestion compared to gelatinized SPS, owing to the increase in resistant starch fraction. It revealed that the different complexes stimulated the growth of Lactobacillus rhamnosus and Bifidobacterium bifidum, while inhibiting the growth of Escherichia coli. Moreover, in vitro fermentation experiments revealed that complexes were utilized by the gut microbiota, resulting in the production of short-chain fatty acids and a decrease in pH. In addition, the polyphenol-SPS complexes altered the composition of gut microbiota by promoting the growth of beneficial bacteria and decreasing pathogenic bacteria. Polyphenol-SPS complexes exhibit great potential for use as a prebiotic and exert dual beneficial effects on gut microbiota.

Enhancing physicochemical, rheological properties, and in vitro rumen fermentation of starch with Melastoma candidum D. Don fruit extract

The utilization of polyphenol-modified starch in ruminants has not undergone extensive exploration. This study aimed to investigate the impact of the complex formed between starch and Melastoma candidum D. Don fruit extract on physicochemical properties, phenol release kinetics in various buffers simulating the gastrointestinal tract, methane production, and post-rumen digestibility. The interaction between starch and M. candidum D. Don fruit extract significantly (p < 0.001) increased resistant starch and particle size diameter. The maximum phenolic release from complex between starch and M. candidum D. Don fruit extract, due to gastrointestinal tract-simulated buffers, ranged from 22.96 to 34.60 mg/100 mg tannic acid equivalent. However, rumen and abomasum-simulated buffers released more phenolic content, whereas the intestine-simulated buffer showed higher antioxidant activity (ferric ion-reducing antioxidant power). Furthermore, complex between starch and M. candidum D. Don fruit extract significantly decreased dry matter rumen digestibility (p < 0.001) and maximum methane gas production (p < 0.001).

Effects of grafting methods and raw materials on the physicochemical properties and biological activities of phenolic acids grafted oat β-glucan

Phenolic acids are commonly used as food biological preservatives. Grafting phenolic acids onto polysaccharides could effectively enhance their biological activities and environmental stability to varying degrees. However, grafting methods and raw materials could affect the physical properties and biological activities of the phenolic acid-grafted polysaccharides. In this study, caffeic acid (CA) and gallic acid (GA) were grafted onto oat β-glucan (OG) and hydrolyzed oat β-glucan (OGH) through N,N'-carbonyldiimidazole-mediated (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride coupling N-hydroxysuccinimide (EDC/NHS) methods. Graft modification decreased the crystallinity and thermal stability of the conjugates, but retained good bioactivities for the conjugates. The antioxidant and bacteriostatic activities of the conjugates prepared by the EDC method were better than those of the CDI method, and the OGH-conjugates showed better biological activities than OG-conjugates. EDC-GAOGH showed best DPPH (89.78%) and ABTS (92.32%) scavenging activities. The inhibitory effect of EDC-GAOGH on Escherichia coli was significantly better than that of EDC-CAOGH, but for Staphylococcus aureus, the results are opposite, which indicating that different phenolic acid grafting products have different inhibitory effects on pathogenic microbes. In general, grafting phenolic acids onto OGH using EDC method is an effective strategy for preparing food biological preservative.

Preparation, physicochemical characterization, and in vitro starch digestibility on complex of Euryale ferox kernel starch with ferulic acid and quercetin

The objective of the current research was to analyze the physicochemical, structural, and in vitro starch digestibility of Euryale ferox kernel starch (EFKS) in complexation with ferulic acid (FA) and quercetin (QR). XRD results have shown that FA and QR were attached to starch resulting crystalline complexes. SEM image showed a smooth, compact structure, indicating FA and QR assist in the reorganization of starch molecules. The 1H NMR spectra of starch-polyphenols complexes showed multiple additional peaks between 6.00 and 9.00 ppm due to the benzene ring and phenolic hydroxyl groups imparted from polyphenols. The shifting and emergence of the characteristic peak observed in the DSC thermogram confirmed that polyphenols were successfully attached to starch. Complexation alters colors, reduced swelling power, and increased the solubility of the complexes. Following the complexation of FA and QR, the content of resistant starch exhibited a significant rise, escalating from 7.69 % (control sample) to 49.39 % (10 % FA) and 54.68 % (10 % QR). This led to a notable reduction in the predicted glycemic index (pGI).The higher resistant starch in the complex is attributed due to the combined effects of the reordered structure of the complexes and the inhibitory activity of polyphenols against starch digestive enzymes. Therefore, EFKS-FA and EFKS-QR complex can be used as a functional ingredient for a low glycemic index food.

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.

Starch modification through its combination with other molecules: Gums, mucilages, polyphenols and salts

Apart from its non-toxicity, biocompatibility and biodegradability, starch has demonstrated eminent functional characteristics, e.g., forming well-defined gels/films, stabilizing emulsions/foams, and thickening/texturizing foods, which make it a promising hydrocolloid for various food purposes. Nonetheless, because of the ever-increasing range of its applications, modification of starch via chemical and physical methods for expanding its capabilities is unavoidable. The probable detrimental impacts of chemical modification on human health have encouraged scientists to develop potent physical approaches for starch modification. In this category, in recent years, starch combination with other molecules (i.e., gums, mucilages, salts, polyphenols) has been an interesting platform for developing modified starches with unique attributes where the characteristics of the fabricated starch could be finely tuned via adjusting the reaction parameters, type of molecules reacting with starch and the concentration of the reactants. The modification of starch characteristics upon its complexation with gums, mucilages, salts, and polyphenols as common ingredients in food formulations is comprehensively overviewed in this study. Besides their potent impact on physicochemical, and techno-functional attributes, starch modification via complexation could also remarkably customize the digestibility of starch and provide new products with less digestibility.

Starches modification with rose polyphenols under multi-frequency power ultrasonic fields: Effect on physicochemical properties and digestion behavior

As the main source of energy for human beings, starch is widely present in people's daily diet. However, due to its high content of rapidly digestive starch, it can cause a rapid increase in blood glucose after consumption, which is harmful to the human body. In the current study, the complexes made from edible rose polyphenols (ERPs) and three starches (corn, potato and pea) with different typical crystalline were prepared separately by multi-frequency power ultrasound (MFPU). The MFPU includes single-frequency modes of 40, 60 kHz and dual-frequency of 40 and 60 kHz in sequential and simultaneous mode. The results of the amount of complexes showed that ultrasound could promote the formation of polyphenol-starch complexes for all the three starches and the amount of ERPs in complexes depended on the ultrasonic parameters including treatment power, time and frequency. Infrared spectroscopy and X-ray diffraction indicated that ERPs with or without ultrasound could interact with the three starches through non-covalent bonds to form non-V-type complexes. Scanning electron microscopy showed that the shape of starches changed obviously from round/oval to angular and the surface of the starches were no longer smooth and appeared obvious pits, indicating that the ultrasonic field destroyed the structure of starches. In addition, compared to the control group, the in vitro digestibility study with 40/60 kHz sonication revealed that ultrasonic treatment greatly improved the digestive properties of the polyphenol-starch complexes by significantly increasing the content of resistant starch (20.31%, 17.27% and 14.98%) in the three starches. Furthermore, the viscosity properties of the three starches were all decreased after ERPs addition and the effect was enhanced by ultrasound both for single- and dual-frequency. In conclusion, ultrasound can be used as an effective method for preparing ERPs-starch complexes to develop high value-added products and low glycemic index (GI) foods.

Complexation of starch and phenolic compounds during food processing and impacts on the release of phenolic compounds

Phenolic compounds can form complexes with starch during food processing, which can modulate the release of phenolic compounds in the gastrointestinal tract and regulate the bioaccessibility of phenolic compounds. The starch-phenolic complexation is determined by the structure of starch, phenolic compounds, and the food processing conditions. In this review, the complexation between starch and phenolic compounds during (hydro)thermal and nonthermal processing is reviewed. A hypothesis on the complexation kinetics is developed to elucidate the mechanism of complexation between starch and phenolic compounds considering the reaction time and the processing conditions. The subsequent effects of complexation on the physicochemical properties of starch, including gelatinization, retrogradation, and digestion, are critically articulated. Further, the release of phenolic substances and the bioaccessibility of different types of starch-phenolics complexes are discussed. The review emphasizes that the processing-induced structural changes of starch are the major determinant modulating the extent and manner of complexation with phenolic compounds. The controlled release of complexes formed between phenolic compounds and starch in the digestive tracts can modify the functionality of starch-based foods and, thus, can be used for both the modulation of glycemic response and the targeted delivery of phenolic compounds.

Synergistic impact of heat-ultrasound treatment on the properties and digestibility of Sagittaria sagittifolia L. starch-phenolic acid complexes

The current research investigated the multi-scale structural interactions between arrowhead starch (AS) and phenolic acids, such as ferulic acid (FA) and gallic acid (GA) to identify the mechanism of anti-digestion effects of starch. AS suspensions containing 10 % (w/w) GA or FA were subjected to physical mixing (PM) followed by heat treatment at 70 °C for 20 min (HT) and a synergistic heat-ultrasound treatment (HUT) for 20 min using a dual-frequency 20/40 KHz system. The synergistic HUT significantly (p < 0.05) increased the dispersion of phenolic acids in the amylose cavity, with GA showing a higher complexation index than FA. XRD analysis showed a typical V-type pattern for GA, indicating the formation of an inclusion complex, while peak intensities decreased for FA following HT and HUT. FTIR revealed sharper peaks possibly of amide bands in the ASGA-HUT sample compared to that of ASFA-HUT. Additionally, the emergence of cracks, fissures, and ruptures was more pronounced in the HUT-treated GA and FA complexes. Raman spectroscopy provided further insight into the structural attributes and compositional changes within the sample matrix. The synergistic application of HUT led to increased particle size in the form of complex aggregates, ultimately improving the digestion resistance of the starch-phenolic acid complexes.

Effect of tea polyphenols on the physicochemical, structural and digestive properties of modified high amylose corn starch

In this study, starch-polyphenol complexes (CES-TPS complexes) were prepared using various ratios (0%, 2%, 4%, 6%, 8%, and 10%, based on starch) of tea polyphenols (TPS) and high amylose corn starch (HACS) pretreated with starch branching enzyme (SBE). It was aimed to determine the effects of TPS on the physicochemical and structural properties and digestibility of the CES-TPS complexes. Scanning electron microscopy and laser particle size analysis showed that the addition of a moderate amount of TPS will reinforce interaction force, while excessive TPS will cause a loose structural morphology, leading to an increase in starch particle size. Thermal property analysis indicated that SBE pre-treatment decreased T_O, T_P and T_C of HACS, and the gelatinization temperature was further reduced after adding TPS. The digestion of CES-TPS complexes was investigated using an Artificial Gut analyzer; the predicted glycemic index of starch samples decreased with the addition of a low concentration of TPS (2-6%), while there was a significant increment in the pGI of starch samples when a high concentration of TPS (8-10%) was added. XRD analysis showed that the relative crystallinity of the CES-TPS complexes further increased to 21.91% and then decreased to 19.38% with the increase of TPS concentration. The ratios of 1047/1022 cm^-1 presented the opposite trend to that determined by FT-IR.

Preparation of Neohesperidin-Taro Starch Complex as a Novel Approach to Modulate the Physicochemical Properties, Structure and In Vitro Digestibility

Neohesperidin (NH), a natural flavonoid, exerts multiple actions, such as antioxidant, antiviral, antiallergic, vasoprotective, anticarcinogenic and anti-inflammatory effects, as well as inhibition of tumor progression. In this study, the NH-taro starch complex is prepared, and the effects of NH complexation on the physicochemical properties, structure and in vitro digestibility of taro starch (TS) are investigated. Results showed that NH complexation significantly affected starch gelatinization temperatures and reduced its enthalpy value (ΔH). The addition of NH increased the viscosity and thickening of taro starch, facilitating shearing and thinning. NH binds to TS via hydrogen bonds and promotes the formation of certain crystalline regions in taro starch. SEM images revealed that the surface of NH-TS complexes became looser with the increasing addition of NH. The digestibility results demonstrated that the increase in NH (from 0.1% to 1.1%, weight based on starch) could raise RS (resistant starch) from 21.66% to 27.75% and reduce RDS (rapidly digestible starch) from 33.51% to 26.76% in taro starch. Our work provided a theoretical reference for the NH-taro starch complex's modification of physicochemical properties and in vitro digestibility with potential in food and non-food applications.

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.

Factors influencing the starch digestibility of starchy foods: A review

Starchy foods are a major energy source of the human diet, their digestion is closely related to human health. Most foods require lots of processing before eating, therefore, many factors can influence starch digestibility. The factors that affect the digestibility of starches have been widely discussed previously, but the extracted starches in those studies were different from those present within the actual food matrix. This review summarizes the factors influencing the starch digestibility in starchy foods. Endogenous non-starch components hinder the starch digestive process. Food ingredients and additives decrease starch digestibility by inhibiting the activity of digestive enzymes or hindering the contact between starch and enzymes. Storage induce the retrogradation of starch, decreasing the digestibility of foods. Therefore, preparing starchy foods with whole grains, processing them as little as possible, using food additives reasonably, and storage conditions may all be beneficial measures for the production of low GI foods.

Conversion of (poly)phenolic compounds in food fermentations by lactic acid bacteria: Novel insights into metabolic pathways and functional metabolites

Lactobacillaceae are among the major fermentation organisms in most food fermentations but the metabolic pathways for conversion of (poly)phenolic compounds by lactobacilli have been elucidated only in the past two decades. Hydroxycinnamic and hydroxybenzoic acids are metabolized by separate enzymes which include multiple esterases, decarboxylases and hydroxycinnamic acid reductases. Glycosides of phenolic compounds including flavonoids are metabolized by glycosidases, some of which are dedicated to glycosides of plant phytochemicals rather than oligosaccharides. Metabolism of phenolic compounds in food fermentations often differs from metabolism in vitro, likely reflecting the diversity of phenolic compounds and the unknown stimuli that induce expression of metabolic genes. Current knowledge will facilitate fermentation strategies to achieve improved food quality by targeted conversion of phenolic compounds.

Electron beam irradiation pretreatment enhances the formation of granular starch-phenolics complexes

Starch-phenolics complex generated by the interaction between starch and phenolic acids had improved characteristics than the native starch, but the efficient preparation of such complex is still challenging. In this study, we proposed a new method for the preparation of starch-phenolics complexes under the pretreatment of electron beam irradiation (EBI). Four structurally similar monomeric phenolic acids including gallic acid (GA), 3,4-Dihydroxy-5-methoxybenzoic acid (3MGA), syringic acid (SA) and vanillic acid (VA), which naturally existed in Tartary buckwheat (TB) seeds, were complexed with native and EBI-pretreated TB starch. The results showed that the complexation between starch and 3MGA was the strongest, more than 30 mg of 3MGA was complexed with 1 g of starch. The complexation did not affect the particle morphology and A-type structure of starch, but changed the crystal structure order and promoted the strength of hydrogen bond, which may lead to the formation of granular complex. EBI pretreatment can significantly promote the complexation by enhancing hydrogen bonds as indicated by a broader band at 3500 ∼ 3100 cm^-1 in the FT-IR spectra. In addition, EBI pretreatment helped to build a tighter bond and higher crystallinity, increase the particle size and iodine binding capacity, and decrease turbidity to inhibit retrogradation of starch. The ¹H NMR of complexes indicated that EBI pretreatment could provide more accessibility for starch to interact with phenolics by creating a spacious microenvironment for ¹H (α1 → 4). Above all, EBI pretreatment enhanced the formations of starch-phenolics complexes.

Effects of hawthorn addition on the physicochemical properties and hydrolysis of corn starch

Hawthorn powder were mixed with corn starch and heated in water to make corn starch-hawthorn mixtures (CS-Haw) and then the physicochemical properties and hydrolysis characteristics of the mixtures were measured. Results showed that the addition of hawthorn powder decreased the viscosity of corn starch, and prolonged the pasting temperature, while the microstructure analysis indicated that hawthorn particles aggregated on the surfaces of starch granules, reducing the chance of starch contacting with water, then delayed the starch gelatinization. The presence of hawthorn powder also reduced the G' value to varying degrees and the loss tangent of CS-Haw was significantly higher than that of corn starch. The addition of hawthorn powder in large amounts also increased the rapidly digestible starch, while decrease the slowly digestible starch and resistant starch. The present research will provide basic theoretical support for the application of hawthorn in healthy starch food processing.

Efficient Retention and Complexation of Exogenous Ferulic Acid in Starch: Could Controllable Bioextrusion Be the Answer?

The starch-phenolics complexes are widely fabricated as functional foods but with low phenolics retention limited by traditional liquid reaction and washing systems. In this study, ferulic acid (FA, 5%) was exogenously used in the crystalline form, and it reacted with starch in a high-solid extrusion environment, which was simultaneously controlled by thermostable α-amylase (0-252 U/g). Moderate enzymolysis (21 or 63 U/g) decreased the degree of the starch double helix and significantly increased the FA retention rate (>80%) with good melting and distribution. Although there were no significantly strong chemical bonds (with only 0.17-2.39% FA bound to starch hydrolysate), the noncovalent interactions, mainly hydrogen bonds, van der Waals forces, and electrostatic interactions, were determined by ¹H NMR and molecular dynamics simulation analyses. The phased release of total FA (>50% in the stomach and ∼100% in the intestines) from bioextrudate under in vitro digestion conditions was promoted, which gives a perspective for handing large loads of FA and other phenolics based on starch carrier.

Physicochemical, Structural, and Digestive Properties of Banana Starch Modified by Ultrasound and Resveratrol Treatments

Ultrasonic treatment combined with resveratrol modification was used to improve banana starch's solubility, thermal stability, and digestion resistance. The solubility and freeze-thaw stability of the modified starch complex significantly increased. The oil-absorption capacity increased by 20.52%, and the gelatinization temperatures increased from 64.10-73.92 °C to 70.77-75.83 °C. The storage modulus (G') and loss modulus (G″) increased after ultrasound and resveratrol treatment, and the proportion of viscosity was increased after composition with resveratrol. Additionally, the in vitro digestibility decreased from 44.12% to 40.25%. The modified complexes had release-control ability for resveratrol. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy demonstrated that complex structures became more compact and organized, whereas crystalline patterns were unchanged. Scanning electron microscopy (SEM) showed that the resveratrol modification caused physical change on the granular surface by creating pores and fissures. The findings can help develop antioxidant functional foods using banana starch.

Polyphenol-Modified Starches and Their Applications in the Food Industry: Recent Updates and Future Directions

Health problems associated with excess calories, such as diabetes and obesity, have become serious public issues worldwide. Innovative methods are needed to reduce food caloric impact without negatively affecting sensory properties. The interaction between starch and phenolic compounds has presented a positive impact on health and has been applied to various aspects of food. In particular, an interaction between polyphenols and starch is widely found in food systems and may endow foods with several unique properties and functional effects. This review summarizes knowledge of the interaction between polyphenols and starch accumulated over the past decade. It discusses changes in the physicochemical properties, in vitro digestibility, prebiotic properties, and antioxidant activity of the starch-polyphenol complex. It also reviews innovative methods of obtaining the complexes and their applications in the food industry. For a brief description, phenolic compounds interact with starch through covalent or non-covalent bonds. The smoothness of starch granules disappears after complexation, while the crystalline structure either remains unchanged or forms a new structure and/or V-type complex. Polyphenols influence starch swelling power, solubility, pasting, and thermal properties; however, research remains limited regarding their effects on oil absorption and freeze-thaw stability. The interaction between starch and polyphenolic compounds could promote health and nutritional value by reducing starch digestion rate and enhancing bioavailability; as such, this review might provide a theoretical basis for the development of novel functional foods for the prevention and control of hyperglycemia. Further establishing a comprehensive understanding of starch-polyphenol complexes could improve their application in the food industry.

Highland Barley Polyphenol Delayed the In Vitro Digestibility of Starch and Amylose by Modifying Their Structural Properties

Slowing starch digestibility can delay or even prevent the occurrence and development of type 2 diabetes. To explore the hypoglycemic potential of highland barley polyphenols (HBP), this study investigated the structural characteristics and starch digestibility of individual or mixed HBP-starch complexes. The results showed that a V-type structure was formed in HBP-starch complexes through non-covalent bonds, resulting in a decrease in rapidly digestible starch and an increase in resistant starch. Specially, the compounding of HBP extracted by acetone significantly reduced the rapidly digestible starch content in amylose from 41.11% to 36.17% and increased the resistant starch content from 6.15% to 13.27% (p < 0.05). Moreover, due to different contents and types of monomer phenols, the HBP extracted with acetone were more effective in inhibiting starch digestion than those extracted with methanol. Ferulic acid and catechin were two key components of HBP. Further results indicated that with the increased content of ferulic acid and catechin (from 1% to 5%), they formed a more ordered structure with amylose, resulting in the lower digestibility of the complex. Collectively, this study suggested that highland barley polyphenols could effectively delay starch digestion by forming a more ordered starch crystal structure. Highland barley polyphenols can be used as functional ingredients in regulating the digestive properties of starchy foods.

Microencapsulated procyanidins by extruding starch improved physicochemical properties, inhibited the protein and lipid oxidant of chicken sausages

Microencapsulated procyanidins by extruding starch (MPS) were used in meat and meat products as an antioxidant for their simple production process and high stability. This study investigated the controlled released properties of MPS and their effect on antioxidant capacity, physicochemical properties, and sensory qualities of chicken sausages during 4°C storage within 28 days. Antioxidant capacity, particle size analysis, and simulated digestion in vitro demonstrated that microencapsulation by extruding starch delayed the procyanidins release. The reduced crystal structure of MPS was determined by the morphology observation (SEM) and the decrease of the typical diffraction peak at 2θ of 20.9° (XRD). The MPS-added sausage had a higher (p < 0.05) ABTS and DPPH radical scavenging ratio (97.6% and 67.3%) and sulfhydryl contents (114.69 nmol/g protein) than other groups. Moreover, lower (p < 0.05) thiobarbituric acid reactive substances (TBARS) (0.67 mg MDA/kg sausage) and carbonyl values (3.24 nmol/mg protein) were detected in MPS-added sausages than others at the end of storage. The MPS addition increased redness (a* value) and decreased the lightness (L* value). The sensory analysis suggested that the sausage with the increased redness was favorable. These results denominated that MPS was an alternative antioxidant in chicken sausages. Practical Application: In this study, microencapsulated procyanidins were prepared by extrusion technology, and the effect on the quality of chicken sausages was investigated, which provides an alternative natural antioxidant for meat and meat products.

Changes in structure and phenolic profiles during processing of steamed bread enriched with purple sweetpotato flour

Purple-fleshed sweetpotato is a rich source of antioxidants such as polyphenols. Chinese steamed bread (CSB) is a popular food product for many people. The effect of CSB making process on the structure and phenolic profiles of CSB enriched with purple sweetpotato flour (PSPF) at different concentrations was investigated. The mixing process greatly reduced the gluten strength due to the incorporation of PSPF. The addition of PSPF induced extensive structural modification on CSB due to the starch-polyphenol and protein-polyphenol interactions. The total phenolic contents, in vitro antioxidant activity, and the contents of hydroxycinnamic acid derivatives were decreased by fermentation and proofing, but they were increased after steaming and storage. The anthocyanins were significantly degraded during the CSB making process. The textural and structural properties of CSB were significantly affected by the PSPF substitutions. The results of this study are useful to develop functional CSB with improved nutritional quality and phenolic profiles.

Physicochemical Characteristics, Microstructure and Health Promoting Properties of Green Banana Flour

This study aimed to investigate the proximate composition, mineral content, functional properties, molecular structure, in vitro starch digestibility, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (DPPH, FRAP) of green banana flour (GBF) cultivars grown in South Africa. With proximate composition, Finger Rose and Pisang Awak had the highest protein (4.33 g/100 g) and fat (0.85 g/100 g) content, respectively. The highest ash content (3.50 g/100 g) occurred with both Grand Naine and FHIA-01 cultivars. Potassium and copper were the most abundant and least minerals, respectively. Pisang Awak cultivar had the highest water absorption capacity (67.11%), while Du Roi had the highest swelling power (0.83 g/g) at 90 °C. Scanning electron microscopy (SEM) images revealed that starch granules from all GBF cultivars were irregular in shape and they had dense surfaces with debris. All the GBF cultivars had similar diffraction patterns with prominent peaks from 15°-24° diffraction angles. The resistant starch (RS) and amylose content of the FHIA-01 cultivar indicates that the GBF has the potential to lower risks of type 2 diabetes and obesity. The highest TPC, TFC and antioxidant activity occurred with the Grande Naine cultivar. Based on their functional characteristics, the Grand Naine and FHIA-01 GBF cultivars could potentially be used as raw materials for bakery products as well as for the fortification of snacks.

Interactions between Phenolic Acids, Proteins, and Carbohydrates-Influence on Dough and Bread Properties

The understanding of interactions between proteins, carbohydrates, and phenolic compounds is becoming increasingly important in food science, as these interactions might significantly affect the functionality of foods. So far, research has focused predominantly on protein-phenolic or carbohydrate-phenolic interactions, separately, but these components might also form other combinations. In plant-based foods, all three components are highly abundant; phenolic acids are the most important phenolic compound subclass. However, their interactions and influences are not yet fully understood. Especially in cereal products, such as bread, being a nutritional basic in human nutrition, interactions of the mentioned compounds are possible and their characterization seems to be a worthwhile target, as the functionality of each of the components might be affected. This review presents the basics of such interactions, with special emphasis on ferulic acid, as the most abundant phenolic acid in nature, and tries to illustrate the possibility of ternary interactions with regard to dough and bread properties. One of the phenomena assigned to such interactions is so-called dry-baking, which is very often observed in rye bread.

Microparticle prepared by chitosan coating on the extruded mixture of corn starch, resveratrol, and α-amylase controlled the resveratrol release

Microcapsule was developed by chitosan coating on the microparticle which was prepared by smashing the extruded mixture of corn starch, resveratrol, and α-amylase. In the preparation process, the low-temperature extrusion and α-amylase were employed to overcome the disadvantages of low gelatinization, dissolution, and poor hydration of extruded starch. Chitosan-coating retarded starch aging, improved the stability of microcapsules, delayed the release of resveratrol. Considering the bioactive functions of chitosan, microcapsules also obtained the functions of chitosan by chitosan coating. The chitosan coating and α-amylase addition improved the release ratio of resveratrol. CESRA (chitosan solution (2%) coating on the extruded mixture of corn starch, resveratrol, and α-amylase) released 86.8% resveratrol at 25 °C in six days chasing, and 85.3% resveratrol at 37 °C in 48 h chasing. Chitosan coating slightly improved the free radical scavenging activity of ABTS⁺. The particle size variation, SEM, XRD, and FT-IR were also employed to investigate the variation of morphology, crystal structure, and chemical composition.

Modulation of gelatinized wheat starch digestion and fermentation profiles by young apple polyphenols in vitro

To evaluate the effect of young apple polyphenols (YAP) on starch digestion and gut microbiota, complexes of native wheat starch (NWS) with YAP, and their main components chlorogenic acid (CA) and phlorizin (P) were fabricated and gelatinized. Through XRD and FTIR analysis, it was found that the partial crystalline structure of NWS was destroyed during gelatinization, and the addition of P decreased the extent of destruction. Then, the gelatinized starchy samples were subjected to in vitro digestion. The wheat starch (WS)-phenolic compound complexes significantly suppressed the digestion rate and increased the proportion of resistant starch (RS) in WS. Furthermore, the residual starchy components after digestion were fermented by human fecal samples for 24 h. The WS-YAP complex greatly increased the concentration of short-chain fatty acids (SCFAs), especially acetic and propionic acids, and enhanced the growth of health-promoting gut microbiota such as Prevotella. Conclusively, YAP was shown to play a positive role in maintaining blood glucose balance and intestinal health.