Search Results (41)

Quercetin (QE), a flavonol-type polyphenol, and oat β-glucan (OβG), a soluble dietary fiber, are natural active ingredients with the potential to reduce the risk of diabetes. OβG slows starch digestion by modifying chyme viscosity, while QE inhibits digestive enzyme activity. This study aimed to explore the formation mechanism and structural characteristics of QE-OβG complexes, as well as their functional properties in terms of viscosity and amylase inhibitory activities. It was found that QE and OβG formed stable non-covalent complexes via hydrogen bonding and hydrophobic interactions. At a mass ratio of 0.6, the binding capacity was relatively high with a moderate aggregation degree, representing a balanced interaction state. Changes in turbidity and particle size indicated that different environmental factors (pH, temperature, ionic strength) exert differential effects on the aggregation behavior of the complex. In addition, the complex exhibited a unique fibrous-block morphology, enhanced thermal stability, improved starch system viscoelasticity, and stronger mixed-type reversible α-amylase inhibition (IC₅₀ = 2.629 mg/mL). This study clarifies the interaction mechanism between QE and OβG, provides a reliable theoretical basis for the development of novel hypoglycemic foods, and offers new insights into multi-component regulation strategies for slow-digestion food design. Full article

Starch–polyphenol complexes have attracted increasing attention as functional ingredients for improving the structural stability and reducing the glycemic potential of starch-based foods, yet their application in extruded fresh noodles remains insufficiently understood. In this study, chestnut starch–resveratrol complexes prepared by heat-moisture synergistic recrystallization treatment (CS-HMRT-Res) were incorporated into extruded fresh noodles, and their quality, structural characteristics, digestibility, and glycemic response were systematically evaluated. Compared with commercial wheat-based Regan noodles, CS-HMRT-Res noodles exhibited enhanced cooking stability (lower swelling and leaching) and improved texture (hardness, chewiness, tensile strength), with a markedly lower total color difference after cooking (ΔE = 1.8 vs. 6.5). SEM, FTIR and XRD indicated a more compact and ordered network; the relative crystallinity of cooked noodles increased to approximately 30.8%. In in vitro digestion, CS-HMRT-Res showed the lowest starch hydrolysis extent at 180 min (45.92%) and yielded a low predicted glycemic index of 53.35, compared with 70.65 for Regan noodles. Consistently, gavage studies in mice confirmed that HMRT-Res-chestnut starch produced the lowest postprandial blood glucose increment response (4.31 mmol/L). Molecular dynamics simulations further suggested that resveratrol could competitively occupy the α-amylase binding cavity and reduce starch accessibility to the enzyme. Overall, CS-HMRT-Res improved processing quality, structural integrity, and reduced glycemic potential, offering a structure-function framework for designing low-GI products. Full article

Flocs, visible particles formed in sugar-sweetened beverages, reduce clarity and consumer acceptance of products. Their presence can be caused not only by different types of trace impurities in the sugar but also by interactions among beverage components. In this review, scientific reports on acid beverage flocs (ABFs) and alcohol flocs are summarized, the main pathways for their formation are described, and practical options for detecting them and preventing their formation in beverages are compiled. Using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 and related guidance, literature searches of Scopus, Web of Science (WoS), PubMed, Food Science and Technology Abstracts (FSTA), CAB Abstracts, and International Commission for Uniform Methods of Sugar Analysis (ICUMSA) resulted in the inclusion of 56 studies. In various types of beverages, complexes formed between proteins (Ps) and polyphenols (PPs) often initiate haze and floc formation, while polysaccharides (dextran, pectin, and starch), silica or silicates, and inorganic ions influence charge balance, particle bridging, and floc growth rate. Ethanol in alcohol beverages can further destabilize colloids and promote aggregation. For beet sugars, saponin–protein interactions are a likely pathway for the formation of ABF, but the available evidence is not consistent. In cane sugars, the reported roles of proteins, polysaccharides, silica, and starch in floc formation vary considerably between studies. For quality assurance, ICUMSA floc tests (GS2-40 and GS2-44) should be complemented by turbidity or haze measurement and colloid characterization such as light scattering, ζ–potential, and infrared IR-based analytical methods supported by chemometrics. Risk mitigation works best as a two-level strategy that combines impurity removal during sugar production and stabilization steps in beverage formulation and storage, including the use of clarification agents and control of pH, temperature, ionic strength, and oxygen exposure. Standardized reporting and validation of rapid predictors against ICUMSA benchmarks remain essential. Full article

Utilizing bamboo residues for the cultivation of Stropharia rugosoannulata is an ecological practice grounded in the concept of agricultural waste recycling, aiming to improve soil microecology and enhance nutrient cycling in bamboo forests. However, a comprehensive and systematic evaluation of the ecological effects of using bamboo residues as cultivation substrates is lacking. To evaluate soil responses following the cultivation of S. rugosoannulata, a field experiment was conducted using bamboo residues pre-fermented with 4% rapeseed cake. The results showed that cultivating S. rugosoannulata with rapeseed cake-fermented bamboo residues significantly enhanced soil nutrient levels and enzyme activities. Notable increases were observed in soil organic carbon, total nitrogen, available nitrogen, and total potassium, as well as in the activities of sucrase, urease, peroxidase, polyphenol oxidase, and neutral protease. Both bacterial and fungal α-diversity were significantly enhanced, and substantial shifts occurred in the community structure and composition of soil microbiota. Metabolomic analysis revealed that significantly differential metabolites were primarily enriched in five key pathways, including purine metabolism, glycerolipid metabolism, biosynthesis of plant secondary metabolites, and starch and sucrose metabolism. Correlation analyses further revealed that specific microbial taxa (four bacterial genera and seven fungal genera) exhibited strong correlations with soil nutrient indicators, whereas another group of taxa (six bacterial phyla and eight fungal genera) was closely linked to soil enzyme activities. Furthermore, bacterial communities were significantly correlated with metabolite variations after substrate addition. Specifically, Firmicutes showed strong positive correlations with multiple metabolites, whereas Planctomycetes exhibited negative correlations with some of the same metabolites, indicating potential competitive interactions. Based on these findings, this study proposes a preliminary “Microbe–Enzyme–Metabolite–Nutrient” coupling cycle, driven by the synergistic interplay among bamboo residues, hypha–microbiome complex, soil enzymes, and functional metabolites. This mechanism provides a scientific explanation for the soil health improvements observed during S. rugosoannulata cultivation and offers theoretical support for the efficient utilization of bamboo waste and maintenance of forest ecosystem stability. Full article

Starch–polyphenol interactions play a critical role in regulating the structural organization and thermal behavior of starch-based systems. In this study, maize starches with different amylose contents were used to systematically investigate how tea polyphenol (TP) complexation influences starch structure and thermal stability. Starch–TP complexes were prepared under thermal-induced conditions and characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). TGA results showed that increasing amylose content slightly reduced the thermal stability of native starches, whereas TP incorporation significantly enhanced thermal resistance, particularly in high-amylose systems. XRD analysis indicated that TP complexation did not affect the crystal structure of starch but led to a pronounced reduction in relative crystallinity, with low-amylose complexes exhibiting predominantly amorphous behavior and high-amylose complexes retaining partial nanocrystalline organization. FTIR spectra revealed reduced short-range molecular order and strengthened hydrogen bonding interactions after TP binding. DSC analysis demonstrated increased gelatinization temperatures accompanied by decreased enthalpy changes, reflecting restricted molecular mobility and delayed solvation of nanocrystalline domains. SEM observations further showed a transition toward denser and more interconnected micro–nano structures with increasing amylose content. Overall, TP preferentially interacts with amylose-rich regions through non-covalent interactions, promoting structural reorganization and enhanced thermal stability of the starch matrix. These findings provide new insight into amylose-dependent starch–polyphenol interactions and offer guidance for designing thermally stable starch-based functional materials. Full article

This study examined how complexes formed between breadfruit starch, lauric acid (LA), and phenolic acids (gallic/GA, 3,4-dihydroxyphenylacetic/DOPAC, caffeic/CA) affect starch digestibility and properties. All complexes increased resistant starch (RS) content from 47.19% (native) to 49.12–70.14%, with the caffeic acid-starch binary complex showing the highest RS (70.14%) and lowest hydrolysis index (52.60). LA-containing samples formed V-type inclusion complexes, evidenced by a cooling-phase viscosity peak, while polyphenol-only samples did not. The formation of the complex raised the starch gelatinization peak temperature from 78.6 °C to 100.6–120.9 °C. Structural analysis indicated increased short-range order and crystallinity. Ternary complexes exhibited lower short-range order but higher crystallinity than binary complexes, suggesting LA primarily influences long-range order, while polyphenols affect both short- and long-range structure. These findings clarify interaction mechanisms in starch–lipid–polyphenol systems for designing low-digestibility foods. Full article

This study investigated the impact of pH adjustment and carrier type on the physicochemical properties, antioxidant activity, thermal stability, hygroscopicity, and particle size distribution of spray-dried model solutions and carrot juice formulations. Model systems were created at varying pH levels (3, 4, 6, 8, and 10) using water alone or with carriers such as octenyl succinic anhydride (OSA)-modified starch (O), trehalose (T), or a combination (OT in a 1:1 ratio at 9–10%). These systems were compared to carrot juice and formulations of carrot juice that included the same carriers. Spray drying was performed at 160 °C using constant feed flow and atomization conditions. In the liquid samples, we measured pH, dry matter, density, conductivity, and color parameters, while the bioactive compounds were analyzed in carrot juice systems. For the powders, we evaluated the dry matter content, color, particle size distribution, morphology, thermal stability, hygroscopicity, and antioxidant activity. Results showed that in model systems, dry matter, density, and conductivity were more affected by the carrier chemistry than pH. Formulations with OSA had lower pH and higher conductivity due to ionizable groups, while trehalose acted neutrally. OSA-trehalose mixtures yielded the highest solids content and stable properties across pH levels, with particle size (D₅₀ range of 18–21 µm) and morphology of the model powders remaining largely unaffected by pH. In carrot juice formulations, however, particle properties were pH-dependent. Acidic conditions (pH 3–4) led to agglomeration and broader size distributions (indicated by increased span values), while neutral to alkaline conditions produced smaller, more uniform particles with improved thermal stability. Neutral to alkaline conditions favored the formation of smaller, more homogeneous particles and improved thermal resistance. The carotenoid content in carrot juice powders increased from approximately 21–23 mg/100 g dry matter (d.m.) under acidic conditions to about 27–30 mg/100 g d.m. at pH 8–10, which was accompanied by higher ABTS antioxidant activity (around 6–9 mg Trolox equivalents (TE)/g d.m.). In contrast, the polyphenol content was highest at low pH levels (approximately 350–420 mg chlorogenic acid (CA)/100 g d.m.), corresponding to elevated DPPH scavenging activity and reducing power, both of which decreased under alkaline conditions. These findings indicate that pH levels and carrier choice significantly affect spray-dried powders. This highlights the importance of validating model system observations in complex food matrices. By adjusting pH and selecting suitable carriers, we can create powders with improved structures, stability, and antioxidant functionality, particularly in foods like carrot juice. Full article

Metabolic illnesses such as obesity, type 2 diabetes and hyperuricemia are becoming more common, driving intensified research into nutritional interventions through targeted dietary modifications as a primary preventive strategy. The apparent fluctuation in blood glucose value is modulated by the digestive behavior of starch. Moreover, polyphenols—historically considered to be anti-nutrients due to their inhibition of digestive enzymes and sometimes astringent taste—can be used to significantly improve the functional properties of starch. This can be achieved primarily through α-amylase inhibition and the modulation of other enzyme activities, alongside the antioxidant and anti-inflammatory effects of polyphenols. Depending on their fine structure, starches are digested at different rates: rapidly digestible starch (RDS) spikes blood glucose; slowly digestible starch (SDS) smooths postprandial blood glucose peaks; resistant starch (RS) feeds gut microbes. The fine structure of starches, such as straight-chain starches, can form complexes with polyphenols through their ‘empty V-type’ structures under controlled processing conditions. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and in vitro digestion modeling analyses have revealed that the formation of starch–polyphenol complexes primarily occurs due to certain interactions (hydrophobic interactions and hydrogen bonding) which lead to stabilized structures, including V-type encapsulation; this significantly increases the content of RSs and slows down enzymatic digestion rates. These complexes lower the GI values of foods via molecular barrier effects, while synergistically boosting antioxidant and anti-inflammatory activities; their anti-digestive capabilities were found to be superior even to those of ordinary starch–lipid compounds. However, limitations persist in the research and application of starch–polyphenol complexes: human bioavailability validation; incomplete mechanistic understanding of multicomponent interactions; industrial scalability challenges due to polyphenol instability. Full article

Off-white or yellowish shoots are common in tea plants (Camellia sinensis L.), and such albino variations are often accompanied by metabolic reprogramming, including increased contents of amino acids and lower levels of polyphenols. Nonetheless, the molecular mechanisms that underlie these albino variations remain to be fully clarified. Here, we examined the ultrastructural characteristics of novel, naturally occurring, yellowish mutated tea leaves and performed metabolomic analyses on green and albino leaves and stems. Then, transcriptomic analyses were also conducted on green and albino leaves to investigate the mechanistic basis of the albino variation. As expected, the cells of albino tea leaves contained fewer and smaller chloroplasts with disorganized thylakoids and smaller starch granules. Widely targeted metabolomics analysis revealed 561 differentially abundant metabolites between green and albino leaves and stems, but there was little difference between green and albino stems. Then, RNA sequencing of green and albino leaves revealed downregulation of genes associated with light harvesting and photosynthesis, and integration of the metabolomic and transcriptomic results indicated that biosynthesis of aromatic amino acids (AAAs) was strongly upregulated in albino leaves. To gain additional insight into the molecular basis of the increased AAA levels, Oxford Nanopore long-read sequencing was performed on green and albino leaves, which enabled us to identify differences in long non-coding RNAs (lncRNAs) and alternatively spliced transcripts between green and albino leaves. Interestingly, the amino acid biosynthesis genes arogenate dehydratase/prephenate dehydratase (ADT) and serine hydroxymethyltransferase (SHMT) were highlighted in the lncRNA and alternative splicing analyses, and the transcription factor genes PLATZ, B3 Os04g0386900, and LRR RLK At1g56140 showed significant changes in both expression and alternative splicing in albino leaves. Together, our data suggest that biosynthesis of AAAs might be crucial for albino mutations in tea plants and could be coordinated with the regulation of lncRNAs and alternative splicing. This is a complex regulatory network, and further exploration of the extensive metabolic reprogramming of albino tea leaves will be beneficial. Full article

Wild fruits are distributed worldwide, but are consumed mainly in developing countries, where they are an important part of the diet. Still, in many other countries, they are consumed only locally. Blackthorn (Prunus spinosa L.) is an underutilized species rich in fibres and phenolic compounds, making it suitable as a potential functional food for supporting human health. Cold (Cw) and hot (Hw) water-extracted (poly)phenolic polysaccharide–protein complexes, differing in carbohydrate, phenolic and protein contents, were isolated from blackthorn fruits and characterized. The complexes exhibited molecular weights of 235,200 g/mol (Cw) and 218,400 g/mol (Hw), and were rich in pectic polymers containing galacturonic acid, arabinose, galactose and rhamnose, indicating a dominance of homogalacturonan (HG) [→4)-α-D-GalA(1→4)-α-D-GalA(1→]n and a low content of RGI [→2)-α-L-Rha(1→4)-α-D-GalA(1→2)-α-L-Rha(1→]n sequences associated with arabinan or arabinogalactan. Minor content of glucan, probably starch-derived, was also solubilized. Pectic polysaccharides were highly esterified and partly acetylated. Pharmacological testing was performed in male Dunkin–Hartley guinea pigs, a model with human-like airway reflexes. Both complexes affected airway defense mechanisms. Particularly, Hw significantly suppressed citric acid-induced cough, similar to codeine, and reduced bronchoconstriction comparably to salbutamol in a dose-dependent manner. These findings support further exploration of Hw as a natural antitussive and bronchodilatory agent. Full article

Given the high incidence of diet-related diseases, including type 2 diabetes and cancer, there is a growing need to explore new strategies for their prevention. Although polyphenols are known to reduce starch digestibility and lower the in vitro glycemic index, their antioxidant capacity and cytotoxic properties, when complexed with starches, remain underexplored. Therefore, this study aimed to investigate the antioxidant activity, total polyphenol content, and cytotoxic potential of polyphenol–starch complexes formed using common dietary polyphenols—(+)-catechin, epigallocatechin gallate, hesperidin, naringenin, trans-ferulic acid, p-coumaric acid, quercetin, and kaempferol—and widely consumed starches from wheat, rice, potato, and maize. Antioxidant activity (FRAP and DPPH) together with the total polyphenols content (Folin–Ciocalteu) were tested: (1) before (undigested) enzymatic hydrolysis of the tested sample; (2) after (digested) enzymatic hydrolysis of the tested sample and (3) after hydrolysis of the sample and its centrifugation (supernatant). Cytotoxicity against colon cancer (Caco-2, HT29) and normal colon (CCD 841CoN) cell lines were determined in vitro by the MTT method. In undigested samples, the highest antioxidant activity was obtained with the addition of quercetin to wheat, rice, and maize starch (6735.8 µmol Fe²⁺/g d.m., 678.8, 539.4 µmol Trolox/g d.m., respectively), and epigallocatechin gallate to wheat, rice, potato, and maize starch (692.1, 538.0, 625.8, 573.6 µmol Trolox/g d.m., respectively). In digested samples, the highest antioxidant activity was obtained with the addition of quercetin to wheat and rice starch (2104.5 µmol Fe²⁺/g d.m., 742.1 µmol Trolox/g d.m., respectively). In the case of the natant of the digested samples, the highest value was recorded for the addition of (+)-catechin to potato starch and trans-ferulic acid to maize starch (823.7 µmol Fe²⁺/g d.m., 245.1 µmol Trolox/g d.m., respectively). The addition of quercetin to wheat and rice starch and (+)-catechin to potato starch (0.239, 0.151, 0.085 g gallic acid/g d.m., respectively) resulted in the highest total polyphenol content. Furthermore, quercetin demonstrated the most significant level of cytotoxic activity against the tumor cell line Caco-2 (IC₅₀ = 275.6 µg/mL; potato starch). Overall, quercetin was identified as the most significant or one of the most significant for all parameters evaluated. Full article

Chestnut flour, obtained through drying and milling of Castanea sativa fruits, has evolved from a subsistence food into a sought-after niche product, appreciated for its naturally gluten-free profile, high starch content, and richness in micronutrients. Over the past decade, its demand has steadily increased due to consumer perception of the health benefits associated with chestnut consumption. As the market for chestnut flour expanded from small-scale to large-scale production, alternative methods to the traditional process were developed. Its distinctive aroma and flavor are strongly influenced by processing methods, which are the focus of this study. Two drying approaches were compared: a traditional smoke-based method (drying house named metato) characterized by a wood-drying method and a controlled laboratory process using a forced-air dryer that maintained a constant temperature of 40 °C. The impact of these methods on the physico-chemical composition, volatile organic compounds (VOCs), and sensory properties of the flour was evaluated using chemical, instrumental, and sensory analyses. The traditional method enhanced the flour’s aromatic complexity and typicity through the application of smoke, which has been demonstrated to generate volatile organic compounds (VOCs), such as guaiacol, furfural, and o-creosol, that are associated with the smoked aroma. Nevertheless, if not properly managed, it can lead to undesirable sensory notes due to excessive smoke exposure. In contrast, the laboratory-controlled process ensured better preservation of bioactive compounds—such as polyphenols (351 mg GAE/100 g dm) and ascorbic acid (322 mg/kg dm)—while retaining the aroma notes associated with fresh chestnuts. Optimizing processing methods may support the valorization of chestnut flour as a high-quality ingredient in the modern gluten-free and functional food market. Full article

The study investigated the physiological response to heat exposure of three potato landraces (Biancona del Faggeto, Rossa delle Macchie, and Quarantina delle Macchie), which are primarily grown in the rural area of Mount Amiata (Grosseto, Tuscany) and are distinguished by specific phylogenetic relationships and nutraceutical composition. Nutraceutical and genetic analyses were performed on tubers collected from the field, whereas physiological assessments were conducted on plants grown in Microcosmo simulators. Overall, nutraceutical analyses revealed tissue-specific differences in the distribution of starch and antioxidants, with ‘Biancona del Faggeto’ and ‘Quarantina delle Macchie’ accumulating more starch in the pulp than in the peel. The level of polyphenols and antioxidants differed between the pulp and the peel, but they accumulated most in the peel of ‘Biancona’. Phylogenetic analysis revealed that ‘Rossa’ and ‘Quarantina’ were more closely related than ‘Biancona’. Given that ‘Biancona’ also contained more starch and antioxidants than the others, this suggests a strong relationship between the phylogeny of the potato varieties and their nutritional content. Heat stress reduced net carbon assimilation and stomatal conductance in all landraces, with ‘Quarantina’ showing the greatest reductions, indicating that stomatal closure is the primary limitation of CO₂ uptake. However, both the maximum and actual quantum yields of photosystem II remained stable under heat stress, indicating that the primary limitation was not caused by damage to photosynthesis light-dependent reactions. These findings highlight the complex interplay between the genetic background and nutraceutical capacity of potato plants, as well as their physiological adaptability to withstand environmental stressors, and provide valuable insights for breeding healthier and more heat-tolerant potato landraces. Full article

In this study, we explored the binding mechanism between tannic acid (TA) and gluten to apply TA as an ingredient in bread-making to evaluate its baking performance and starch digestion. The interaction was systematically investigated by analyzing binding affinity, binding mode, and matrix structure of the TA–gluten complex using fluorescence quenching, molecular docking, and confocal laser scanning microscopy. TA strongly interacted with gluten via non-covalent interactions, mainly hydrogen bonds, and formed the major hydrogen bonds with six different glutamines (Q32, Q108, Q313, Q317, Q317, and Q349), which play a critical role in gluten network construction among amino acid residues of gluten. Additionally, TA showed lower binding affinity toward glutenin (−10.4 kcal/mol) compared to gliadin (−8.9 kcal/mol), implying stronger binding with glutenin. Consequently, the interaction between TA and gluten created a dense and compact gluten network structure. It influenced baking performance, causing a decrease in bread loaf volume while an increase in firmness and lowering the starch digestion rate, increasing slowly digestible starch and resistant starch fractions. This study identified the binding mechanism of TA toward gluten and provides better insights into how to apply TA or perhaps other polyphenols to design functional bakery products to control starch digestion rate. Full article

To investigate the impact of tea polyphenols on the thermodynamic properties, gelatinization properties, rheological properties, and digestion characteristics of starch after ball milling, canna starch and tea polyphenols were mixed at a 10:1 ratio (w/w) in an experiment and processed with different ball milling times. After ball milling for 3 h, the tea polyphenols and starch fragments formed complexes. Compared with the unmilled mixture, the solubility increased by 199.4%; the shear stress decreased by 89.48%; and the storage modulus and loss modulus decreased. The content of resistant starch first decreased and then increased. Infrared results revealed that ball milling led to a non-covalent interaction between the tea polyphenols and starch. Molecular dynamics simulations were used to study the interaction between the starch and tea polyphenols. The binding free energy of the main component, epigallocatechin gallate (EGCG), in tea polyphenols with starch was reduced from −23.20 kcal/mol to −26.73 kcal/mol. This experiment can provide a reference for the development of functional starch with high resistant starch content. Full article