Physicochemical interactions between rice starch and caffeic acid during boiling

Reactive extrusion fabrication of thermoplastic starch with Ca2+ heterodentate coordination structure for harvesting multiple-reusable PBAT/TPS films

Creating multiple-reusable PBAT/TPS (PT) films presents a novel solution to reduce carbon emissions from disposable packaging, addressing challenges like the high creep of PBAT and the glycerol migration of TPS. Consequently, adopting reactive extrusion to fabricate reversible cross-linking TPS with high shape memory performance, low migration, and homogeneous dispersion in PBAT matrix was a fascinating strategy. Herein, starch, glycerol and CaCl2 (calcium chloride) were extruded to fabricate TPS-Ca with Ca2+ heterodentate coordination structure and confirmed by XPS, 1H NMR and temperature-dependent FTIR. The results of DMA, dynamic rheology, flow activation energy and SEM revealed that TPS-Ca exhibited significant temperature-sensitive reversible properties and robust melt flow capability, enabling micro-nano scale dispersion in PBAT. Noteworthy, PBAT/TPS-Ca (PT-Ca) would recover 100 % length within 20 s by microwave heating after being loaded under the hygrothermal environment. Meanwhile, the migration weight of glycerol decreased from 2.5 % to 1.2 % for the heat-moisture-treated PBAT/TPS (HPT) and PBAT/TPS-Ca (HPTCa). Remarkably, the tensile strength and elongation at the break of HPT-Ca increased to 20.0 MPa and 924 %, respectively, due to reduced stress concentration sites in the phase interface. In summary, our study provides a streamlined strategy for fabricating multiple-reusable PT, offering a sustainable solution to eliminate carbon emissions linked to disposable plastic.

Elucidating the influence and mechanism of different phenols on the properties, food quality and function of maize starch

This study discusses interaction differences between three phenols (protocatechuic acid, naringin and tannic acid) and starch helix, investigates influences of phenols at different doses on properties of maize starch, and further determines their effects on quality and function of maize-starchy foods. Simulated results indicate variations of phenolic structure (phenolic hydroxyl group amount, glycoside structure and steric hindrance) and dose induce phenols form different complexes with starch helix. Formation of different starch-phenols complexes alters gelatinization (1.65-5.63 J/g), pasting form, water binding capacity (8.83-12.69 g/g) and particle size distribution of starch. Meanwhile, differences in starch-phenols complexes are reflected in fingerprint area (R1045/1022: 0.920 to 1.047), crystallinity (8.3% to 17.0%), rheology and gel structure of starch. Additionally, phenols change texture and color of cold maize cake, giving them different antioxidant capacity and lower digestibility. Findings are beneficial for understanding interaction between starch and different phenols and their potential application.

Structure-function relationships in (poly)phenol-enzyme binding: Direct inhibition of human salivary and pancreatic α-amylases

(Poly)phenols inhibit α-amylase by directly binding to the enzyme and/or by forming starch-polyphenol complexes. Conventional methods using starch as the substrate measure inhibition from both mechanisms, whereas the use of shorter oligosaccharides as substrates exclusively measures the direct interaction of (poly)phenols with the enzyme. In this study, using a chromatography-based method and a short oligosaccharide as the substrate, we investigated the detailed structural prerequisites for the direct inhibition of human salivary and pancreatic α-amylases by over 50 (poly)phenols from the (poly)phenol groups: flavonols, flavones, flavanones, flavan-3-ols, polymethoxyflavones, isoflavones, anthocyanidins and phenolic acids. Despite being structurally very similar (97% sequence homology), human salivary and pancreatic α-amylases were inhibited to different extents by the tested (poly)phenols. The most potent human salivary α-amylase inhibitors were luteolin and pelargonidin, while the methoxylated anthocyanidins, peonidin and petunidin, significantly blocked pancreatic enzyme activity. B-ring methoxylation of anthocyanidins increased inhibition against both human α-amylases while hydroxyl groups at C3 and B3' acted antagonistically in human salivary inhibition. C4 carbonyl reduction, or the positive charge on the flavonoid structure, was the key structural feature for human pancreatic inhibition. B-ring glycosylation did not affect salivary enzyme inhibition, but increased pancreatic enzyme inhibition when compared to its corresponding aglycone. Overall, our findings indicate that the efficacy of interaction with human α-amylase is mainly influenced by the type and placement of functional groups rather than the number of hydroxyl groups and molecular weight.

Persimmon leaf polyphenols as potential ingredients for modulating starch digestibility: Effect of starch-polyphenol interaction

The interaction mode between persimmon leaf polyphenols (PLP) and corn starch with different amylose content and its effect on starch digestibility was studied. Results of iodine binding test, TGA, and DSC revealed that PLP interacted with starch and reduced the iodine binding capacity and thermal stability of starch. High amylopectin corn starch (HAPS) interacted with PLP mainly via hydrogen bonds, since the FT-IR of HAPS-PLP complex showed higher intensity at 3400 cm-1 and an obvious shift of 21 cm-1 to shorter wavelength, and the chemical shifts of protons in 1H NMR and the shift of C-6 peak in 13C NMR of HAPS moved to low field with the addition of PLP. Results of 1H NMR also showed the preferential formation of hydrogen bonds between PLP and OH-3 of HAPS. Different from HAPS, PLP formed V-type inclusion complex with high amylose corn starch (HAS) because XRD of HAS-PLP complex showed characteristic feature peaks of V-type inclusion complex and C-1 signal in 13C NMR of PLP-complexed HAS shifted to low field. Interaction with PLP reduced starch digestibility and HAS-PLP complex resulted in more resistant starch production than HAPS-PLP complex. To complex PLP with starch might be a potential way to prepare functional starch with slower digestion.

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.

Formation and Application of Starch-Polyphenol Complexes: Influencing Factors and Rapid Screening Based on Chemometrics

Understanding the nuanced interplay between plant polyphenols and starch could have significant implications. For example, it could lead to the development of tailor-made starches for specific applications, from bakinag and brewing to pharmaceuticals and bioplastics. In addition, this knowledge could contribute to the formulation of functional foods with lower glycemic indexes or improved nutrient delivery. Variations in the complexes can be attributed to differences in molecular weight, structure, and even the content of the polyphenols. In addition, the unique structural characteristics of starches, such as amylose/amylopectin ratio and crystalline density, also contribute to the observed effects. Processing conditions and methods will always alter the formation of complexes. As the type of starch/polyphenol can have a significant impact on the formation of the complex, the selection of suitable botanical sources of starch/polyphenols has become a focus. Spectroscopy coupled with chemometrics is a convenient and accurate method for rapidly identifying starches/polyphenols and screening for the desired botanical source. Understanding these relationships is crucial for optimizing starch-based systems in various applications, from food technology to pharmaceutical formulations.

White rice enrichment with phenols upon cooking in olive leaf infusion: a preliminary study

BACKGROUND

White rice is poor in health-promoting phytochemicals; therefore, the production of a phenol-enriched commodity is highly desirable. Recent findings on its enrichment via cooking in plant extracts are promising, yet studies employing aqueous extracts of olive leaves (OLs), containing well-recognized bioactive phenols (e.g. oleuropein) are absent. In addition, little is known about the levels of phenols that are maintained after rice drying and rehydration, an important aspect for the future design of 'ready-to-eat' functional rice.

RESULTS

The examination, for the first time, of white rice adsorption capacity of phenols from OLs upon cooking in infusions containing different levels of phenols, after freeze-drying and rehydration, showed the following: (i) the total phenol content, the antioxidant activity (assessed via 2,2-diphenyl-1-picrylhydrazyl radical and ferric reducing antioxidant power assays), the oleuropein and luteolin-7-O-glucoside levels increased dose dependently; (ii) upon rehydration, the average decrease of total phenol content and antioxidant activity values was significantly lower when an exact volume of water was used compared with an excess (~10% versus 63%). A similar trend was observed for oleuropein (36% versus 83%) and the luteolin-7-O-glucoside (24 versus 82%) levels; (iii) the dried enriched kernels were less bright with a hay-yellow hue (CIELab coordinates).

CONCLUSION

White rice enrichment with biophenols from OLs, a by-product of olive tree cultivation, was successful using a simple approach. Despite leaching upon freeze-drying/rehydration, sufficient amounts were maintained to obtain a functional rice that could serve as an alternative dietary source of OLs phenols to non-traditional olive tree product consumers or those refraining from sodium and fats. © 2023 Society of Chemical Industry.

Lowering glycemic levels via gastrointestinal tract factors: the roles of dietary fiber, polyphenols, and their combination

Dietary fiber (DF) and polyphenols (DP) are typical blood sugar-lowering components, and both play distinct yet interconnected roles in exerting their blood sugar-lowering effects. We comprehensively summarized the single and combined effects of DF and DP on blood glucose homeostasis through regulating the relevant factors in the upper gastrointestinal tract (UGT) and lower gastrointestinal tract (LGT). In the UGT, DF slowed down glucose metabolism by enhancing digesta viscosity and hindering enzyme-substrate interaction. DP primarily targeted enzymes and substrates. When combined, DP enhanced the adsorption capacity of DF for glucose. DF weakened DP's inhibitory effect on enzymes. Both DF and DP disrupted glucose intestinal uptake via physical or genomic modulation, but the co-consumption of DF and DP demonstrated a lower inhibitory effect on glucose uptake than DP alone. In the LGT, DF and DP showed synergistic or antagonistic effects on gut microbiota. Remarkably, whole foods exhibited potent prebiotic effects due to their compound-rich matrix, potentially enhancing glucose homeostasis and expanding dietary options for glucose regulation research.

Comprehensive metabolomic variations of hawthorn before and after insect infestation based on the combination analysis of 1H NMR and UPLC-MS

Hawthorn, the sliced and dried ripe fruits of Crataegus pinnatifida Bge. Var. Major N. E. Br. (Rosaceae), is an edible and medicinal substance with a variety of health-promoting benefits. Hawthorn needs to be stored in warehouses after harvesting to meet people's perennial demand. However, it is easily infested by insects of Plodia interpunctella and Tribolium castaneum during storage, which inevitably leads to poor quality and causes adverse effects on people's health. So far, there has been no report on insect-infested hawthorn. In this study, we analyzed the changes of metabolites in hawthorn before and after insect infestation and screened out potential biomarkers to effectively and quickly detect the occurrence of insect infestation. A combination analysis of 1H nuclear magnetic resonance (NMR) and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) was used to identify the primary and secondary metabolites. By the comparison of hawthorn and insect-infested hawthorn samples, it was found that the differences were mainly manifested in the content of metabolites. The metabolites of 32 and 1463 were identified by 1H NMR and UPLC-MS analysis, respectively. According to the parameters of VIP >1 and P < 0.05, 10 differential metabolites were screened from 1H NMR analysis. Based on the parameters of VIP >1.0, P < 0.05, and (FC) > 1 or < 1, 47 differential metabolites were screened from UPLC-MS analysis. Therefore, a total of 57 differential metabolites were considered as differential biomarkers. The heat map analysis showed that the content of some differential biomarkers with significant pharmacological activities decreased after insect infestation. Through receiver operating characteristic (ROC) curve assessment, 52 differential biomarkers (6 of 1H NMR analysis and 46 of UPLC-MS analysis) were screened to distinguish whether insect infestation occurred in hawthorn. This is the first report on the changes of metabolites between hawthorn and insect-infested hawthorn and on the screening of differential biomarkers for monitoring insects. These results contributed to evaluate quality of hawthorn and ensure food safety for consumers. It also laid a foundation for further research on the infestation mechanism and safe storage monitoring in hawthorn.

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.

Effect of proanthocyanidins from different sources on the digestibility, physicochemical properties and structure of gelatinized maize starch

The effect of proanthocyanidins (PAs) from Chinese bayberry leaves (BLPs), grape seeds (GSPs), peanut skins (PSPs) and pine barks (PBPs) on physicochemical properties, structure and in-vitro digestibility of gelatinized maize starch was investigated. The results showed that all PAs remarkably retarded starch digestibility, meanwhile, BLPs highlighted superiority in increasing resistant starch content from 31.29 ± 1.12 % to 68.61 ± 1.15 %. The iodine-binding affinity analysis confirmed the interaction between PAs and starch, especially the stronger binding of BLPs to amylose, which was driven by non-covalent bonds supported by XRD and FT-IR analysis. Further, we found that PAs altered the rheological properties, thermal properties and morphology structure of starch. In brief, PAs induced larger consistency, poorer flow ability, lower gelatinization temperatures and melting enthalpy change (ΔH) of starch paste. SEM and CLSM observation demonstrated that PAs facilitated starch aggregation. Our results indicated that PAs especially BLPs could be considered as potential additives to modify starch in food industry.

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.

Antioxidant and Antidiabetic Properties of Phlorotannins from Ascophyllum nodosum Seaweed Extracts

Seaweeds have gained considerable attention in recent years due to their potential health benefits and high contents of bioactive compounds. This review focuses on the exploration of seaweed's health-promoting properties, with particular emphasis on phlorotannins, a class of bioactive compounds known for their antioxidant and antidiabetic properties. Various novel and ecofriendly extraction methods, including solid-liquid extraction, ultrasound-assisted extraction, and microwave-assisted extraction are examined for their effectiveness in isolating phlorotannins. The chemical structure and isolation of phlorotannins are discussed, along with methods for their characterization, such as spectrophotometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and chromatography. Special attention is given to the antioxidant activity of phlorotannins. The inhibitory capacities of polyphenols, specifically phlorotannins from Ascophyllum nodosum against digestive enzymes, such as α-amylase and α-glucosidase, are explored. The results suggest that polyphenols from Ascophyllum nodosum seaweed hold significant potential as enzyme inhibitors, although the inhibitory activity may vary depending on the extraction conditions and the specific enzyme involved. In conclusion, seaweed exhibits great potential as a functional food ingredient for promoting health and preventing chronic diseases. Overall, this review aims to condense a comprehensive collection of high-yield, low-cost, and ecofriendly extraction methods for obtaining phlorotannins with remarkable antioxidant and antidiabetic capacities.

Construction of caffeic acid modified porous starch as the dual-functional microcapsule for encapsulation and antioxidant property

A dual-functional food-grade microcapsule, which was constructed by caffeic acid and porous starch was obtained. Caffeic acid modified porous starch (CA-PS) was accordingly synthesized successfully by esterification. Carbonyl signal observed by ¹³C solid state NMR (170 ppm) and FT-IR (1745 cm^-1), indicating the formation of ester bond. BET of CA-PS was determined as 44.8 m²/g by N₂ adsorption analysis. The results proved CA-PS has both excellent adsorption and antioxidant activity. Furthermore, it has been applied for encapsulation of linoleic acid (LA) to prevent its degradation effectively, because LA adsorbed in porous adsorbents without antioxidant activity may still suffer serious oxidation. Besides, ¹H NMR Integral of LA did not show a significant decay. This observation demonstrated CA-PS indeed has the better performance on protection of LA than PS. We expect this work will boost research on designing and employing multi-functional starchy materials for further applications.

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.

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.

Comparative Evaluation of Hydrothermally Produced Rice Starch-Phenolic Complexes: Contributions of Phenolic Type, Plasma-Activated Water, and Ultrasonication

A thorough investigation of the viability of rice starch conjugation with three different phenolic compounds-gallic acid, sinapic acid, and crude Mon-pu (Glochidion wallichianum Muell Arg) (MP) extract-was conducted using a variety of developed methods which modified the techno-functionality and digestibility of the end product. With and without the aid of ultrasonication (US), phenolic compounds were complexed with hydrothermally pre-gelatinized rice starch prepared using distilled water or plasma-activated water (PAW). The in vitro digestibility, structural features, rheological and thermal properties, and in vitro antioxidant activity of starch-phenolic complexes were evaluated. The US-assisted starch-MP complex in water had the highest complexing index (CI) value (77.11%) and resistant starch (RS) content (88.35%), resulting in a more compact and stable ordered structure. In all complexes, XRD revealed a new minor crystalline region of V-type, which was stabilized by hydrogen bonding as defined by FTIR and H¹-NMR. Polyphenols caused a looser gel structure of starch, as imaged by a scanning electron microscope (SEM). Starch-phenolic complexes outperformed other complexes in terms of in vitro antioxidant activity. Gallic acid addition to starch molecules boosted DPPH scavenging activity, notably when synthesized in PAW regardless of US assistance, although having lower CI and RS values than the MP complex. Therefore, this research lays the groundwork for the efficient production of functional food ingredients based on rice starch and polyphenols.

Interactions between Ascophyllum nodosum Seaweeds Polyphenols and Native and Gelled Corn Starches

The effect of several blending procedures between Ascophyllum nodosum seaweed flour (AF) and corn starch (CS) on the interactions between polyphenols and starch was studied in this paper. These methods comprised the blending of AF with native starch (NT) with previously gelled starch gel (GL) and promoting the gelling of corn starch in the presence of AF (CGL). Different AF-CS (g/g) ratios (from 1:0.5 to 1:25) were studied. The liquid phase was chemically characterized by polyphenols (TPC) and carbohydrates content. The antioxidant activity of the liquid phase after achieving the solid-liquid equilibrium was determined by DPPH, ABTS, and FRAP methods. The solid phase was characterized by FT-IR and SEM techniques. The Halsey model successfully fitted the equilibrium TPC in liquid and polyphenols adsorbed/retained by the solid phase of tested systems. NT samples showed lower polyphenols sorption than gelled samples. The differences found between samples obtained with GL and CGL methods suggested different interactions between polyphenols and starch. Specifically, physisorption is predominant in the case of the GL method, and molecular trapping of polyphenols in the starch gel structure is relevant for the CGL method. Results allowed us to determine the enhancement of the retention of polyphenols to achieve starchy foods with high bioactivity.

Understanding phenolic acids inhibition of α-amylase and α-glucosidase and influence of reaction conditions

Phenolic acids are involved in modulating the activity of starch digestive enzymes but remains unclear if their interaction with enzymes or starch is governing the inhibition. The potential inhibition of nine phenolic acids against α-amylase and α-glucosidase was studied applying different methodologies to understand interactions between phenolic acids and either enzymes or substrates. Vanillic and syringic acids were prone to interact with α-amylase requiring low half-maximum inhibitory concentration (IC₅₀) to inhibit starch hydrolysis. Nevertheless, the initial interaction of phenolic acids with starch somewhat obstructed their interaction with starch, requiring 10 times higher IC₅₀, with the exception of chlorogenic and gallic acid. The study demonstrates that 10% of the phenolic acids were retained during starch gelatinization. Those effects were not really evident with α-glucosidase, likely due to the small molecular size of maltose substrate. Phenolic acids with > 1 hydroxyl group like caffeic and protocatechuic acids showed the lowest IC₅₀ against α-glucosidase.

New Techniques in Structural Tailoring of Starch Functionality

Inherent characteristics of native starches such as water insolubility, retrogradation and syneresis, and instability in harsh processing conditions (e.g., high temperature and shearing, low pH) limit their industrial applications. As starch properties mainly depend on starch composition and structure, structural tailoring of starch has been important for overcoming functional limitations and expanding starch applications in different fields. In this review, we first introduce the basics of starch structure, properties, and functionalities and then describe the interactions of starch with lipids, polysaccharides, and phenolics. After reviewing genetic, chemical, and enzymatic modifications of starch, we describe current progress in the areas of porous starch and starch-based nanoparticles. New techniques, such as using the CRISPR-Cas9 technique to tailor starch structures and using an emulsion-assisted approach in forming functional starch nanoparticles, are only feasible when they are established based on fundamental knowledge of starch. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Effects of Three Types of Polymeric Proanthocyanidins on Physicochemical and In Vitro Digestive Properties of Potato Starch

The effects of three types of polymeric proanthocyanidins (PPC) with different degrees of polymerization (DP), namely PPC1 (DP = 6.39 ± 0.13), PPC2 (DP = 8.21 ± 0.76), and PPC3 (DP = 9.92 ± 0.21), on the physicochemical characteristics and in vitro starch digestibility of potato starch were studied. PPC addition (5%, w/w) increased the gelatinization temperature and decreased some viscosity indices of potato starch, including the peak, trough, breakdown, and setback viscosities. Starch-PPC pastes showed reduced thixotropy and improved stability and gelling properties compared to starch paste. The three types of proanthocyanidins all showed evident inhibitory effects on the digestion and retrogradation of potato starch, including short-term and long-term retrogradation. Among the three, PPC with a lower DP had stronger effects on the starch short-term retrogradation and gelling performance, whereas larger PPC molecules exhibited a greater impact on starch recrystallization and digestive characteristics. The research consequences were conducive to explore the application of functional PPC in starch-based food processing.

Interaction with longan seed polyphenols affects the structure and digestion properties of maize starch

This study investigated effects of longan seed polyphenols (LSPs) on the structure and digestion properties of starch, and discussed the interaction mechanism between starch and LSPs. The results showed cooking with 20 % LSPs did not change amylopectin chain length distribution of normal maize starch, however, the amylose content was reduced from 21.60 to 14.03 %. This suggests LSPs may interact with starch via non-covalent bond. Isothermal titration microcalorimetry and XRD results confirmed the existence of non-covalent interaction, and indicated that LSPs may enter the hydrophobic cavity of amylose, forming V-type inclusion complex. LSPs did not affect gelatinization temperatures of maize starch, whereas 20 % LSPs decreased the enthalpy change by about 26 %. The digestion results indicate significant inhibition effect of LSPs on the digestion of cooked starch, attributing to the interaction of LSPs with starch. These suggest potential applications of LSPs as functional ingredients in modulating postprandial glycemic response of starchy food.

Applications of nuclear magnetic resonance spectroscopy to the evaluation of complex food constituents

Due to a number of unparalleled advantages such as fastness, accuracy, intactness, nuclear magnetic resonance spectroscopy (NMR) has fulfilled a significant role in determining structures and dynamics of various physical, chemical and biological systems in the field of food analysis. This study introduced the principle of NMR, key NMR techniques such as ¹H NMR, DOSY, NOESY, HSQC, etc., and the knowledge of NMR applications on the evaluation of complex food system, especially the interactions of food components. The reviewed research work provides sufficient evidence that NMR spectroscopy has been an invaluable tool and will play an increasingly important role in specific technical support for food assessment. In addition, NMR combined with various other technologies could give a complete picture of the mechanism of the performance of functional food compounds, which are vital for human health and influence the intrinsic food properties during processing, storage and transportation at the molecular level.

Diverse effects of rutin and quercetin on the pasting, rheological and structural properties of Tartary buckwheat starch

We investigated the interactions of two main phenolics, rutin and quercetin, with starch, the primary component of Tartary buckwheat. The addition of rutin or quercetin significantly affected the structural and physicochemical properties of the starch, and rutin showed a stronger effect than quercetin, particularly at a dose of 6% (w/w). Rutin better enhanced the aggregation of starch pastes and gel formation than quercetin according to our pasting, rheological and thermal property analyses. A scanning electron microscopy analysis of its morphology showed that rutin was more easily dispersed in starchy matrix than quercetin and acted as rigid fillers for gels. The nuclear magnetic resonance results showed different binding sites due to the steric hindrance of the rutin disaccharide groups (rutinose). These findings provide fundamental information about applying rutin during the whole grain processing of Tartary buckwheat.

Processed Fruiting Bodies of Lentinus edodes as a Source of Biologically Active Polysaccharides

Water soluble polysaccharides (WSP) were isolated from Lentinus edodes fruiting bodies. The mushrooms were previously subjected to various processing techniques which included blanching, boiling, and fermenting with lactic acid bacteria. Therefore, the impact of processing on the content and biological activities of WSP was established. Non-processed fruiting bodies contained 10.70 ± 0.09 mg/g fw. Boiling caused ~12% decrease in the amount of WSP, while blanched and fermented mushrooms showed ~6% decline. Fourier transform infrared spectroscopy analysis (FTIR) confirmed the presence of β-glycosidic links, whereas due to size exclusion chromatography 216 kDa and 11 kDa molecules were detected. WSP exhibited antioxidant potential in FRAP (ferric ion reducing antioxidant power) and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assays. Cytotoxic properties were determined on MCF-7 and T47D human breast cell lines using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) test. Both biological activities decreased as the result of boiling and fermenting.

Absorption of Phenolic Acids in Rice Kernels after Boiling in Spearmint Aqueous Extracts of Different Concentrations. A Diffusion Study

In this study, an attempt was made to fortify white milled rice grains with phenolic compounds using a hydrothermal process and spearmint aqueous extracts of different % w/v concentrations. In addition, a mathematical model was acquired in order to simulate the diffusion of specific phenolic acids in rice kernels during boiling inside the extracts. Results showed that the amount of phenolic acids in rice, the potential equilibrium concentration values, as well as the diffusivity of these compounds in rice material were positively affected by the increase in % w/v bulk concentration of the aqueous extract. It was also shown that the diffusion process could be sufficiently described by a Fickian model and the estimated diffusion coefficients ranged from 6.86 × 10^-12 to 3.56 × 10^-11 m² /s, with the p-coumaric acid presenting the highest average diffusivity in boiling rice material among all examined compounds. The chemical affinity of each phenolic acid to rice macromolecules was believed to play the most important role concerning their diffusivity in rice during fortification process. PRACTICAL APPLICATION: Consumer's interest for functional food products is constantly growing during the last decades. This study may act as preliminary for the production of fortified rice products, possessing adjusted bioactive content, in industrial scale. The proposed methodology for the production of quick-cooking or ready-to-eat fortified rice may be adopted by rice industries and applied by only making slight modifications in their existing parboiling units.