Interaction of Sorghum Tannins with Wheat Proteins and Effect on in Vitro Starch and Protein Digestibility in a Baked Product Matrix

Investigating the effect of whey protein isolate:proanthocyanidin complex ratio on the stability and antioxidant capacity of Pickering emulsions

Whey protein isolate (WPI) has the potential to be a Pickering stabilizer, but its applications in emulsions are restricted due to its structural susceptibility to external environments. Proanthocyanidin (PAC) is a natural antioxidant polyphenol that can improve protein properties and enhance the stability and longevity of emulsions. In the current work, PACs were employed to bind WPIs, forming a complex to stabilize Pickering emulsion. Fluorescence spectroscopy, infrared spectroscopy, confocal microscopy, quartz crystal microbalance with dissipation monitoring (QCM-D), and antioxidant stability of the emulsion were performed to characterize the structural changes of the protein/polyphenol complexes and their effects on the interfacial properties and stability of the emulsion. Results indicated that PACs and WPIs might bind through hydrogen bonding and hydrophobic interactions, effectively increasing the hydrophilicity of the complexes. QCM-D and emulsion stability showed that adsorption at the oil-water interface of the complexes was the largest, and the stability of the Pickering emulsion was optimal when the concentration ratio of PAC to WPI exceeded 1:1. The antioxidant properties of Pickering emulsions were positively correlated with the addition of PACs. These findings demonstrated that PACs could improve the properties of WPIs and enhance the stability and antioxidant properties of WPI Pickering emulsions.

Effect of sorghum bran addition on antioxidant activities, sensory properties, and in vitro starch digestibility of Chinese southern-style steamed bread

BACKGROUND

Chinese steamed bread (CSB) is one of the most important staple foods in China and is also popular in South-East Asia. Developing functional CSB could improve people's resistance to inflammatory and non inflammatory diseases. This work investigated the effect of sorghum bran addition on antioxidant activities, sensory properties, and in vitro starch digestibility of Chinese southern-style steamed bread (CSSB).

RESULTS

In this study, the enhanced CSSB with 0-200 g kg-1 of fine black and tannin (sumac) sorghum bran addition was developed. A small change in phenol content and antioxidant activity was observed at various stages in the processing procedure before steaming. Moreover, a high retention of antioxidant phenolics CSSB with sorghum bran addition was observed. Sorghum bran addition significantly increased the total phenol content and antioxidant activity of CSSB by 4.5-10 times, on average, relative to control. Sorghum bran addition significantly also increased the content of resistant starch, and significantly decreased in vitro starch digestibility in CSSB; these effects were likely due to the joint inhibitory effect of tannins and ferulic acid on starch digestibility. Interestingly, the sorghum bran breads scored higher or similar to control in sensory color preference and overall appearance, but lower on most textural and mouthfeel attributes.

CONCLUSION

Sorghum bran addition significantly increased the antioxidant activity of CSSB and significantly decreased starch digestibility. Moreover, the color and appearance properties were maintained or improved. However, the sensorial textural attributes were negatively impacted by the sorghum bran substitutions. Strategies to improve the texture of bran-fortified breads would likely enhance their consumer acceptability. © 2024 Society of Chemical Industry.

Plant-Based Protein-Phenolic Interactions: Effect on different matrices and in vitro gastrointestinal digestion

This review summarizes the literature on the interaction between plant-based proteins and phenolics. The structure of the phenolic compound, the plant source of proteins, matrix properties (pH, temperature), and interaction mechanism (covalent and non-covalent) change the secondary structure, ζ-potential, surface hydrophobicity, and thermal stability of proteins as well as their functional properties including solubility, foaming, and emulsifying properties. Studies indicated that the foaming and emulsifying properties may be affected either positively or negatively according to the type and concentration of the phenolic compound. Protein digestibility, on the other hand, differs depending on (1) the phenolic concentration, (2) whether the food matrix is ​​solid or liquid, and (3) the state of the food-whether it is heat-treated or prepared as a mixture without heat treatment in the presence of phenolics. This review comprehensively covers the effects of protein-phenolic interactions on the structure and properties of proteins, including functional properties and digestibility both in model systems and real food matrix.

The additive interactions between high-molecular-weight glutenin subunits and tannic acid improve the wheat quality

Wheat gluten proteins, especially high-molecular-weight glutenin subunits (HMW-GS), are the main contributor to flour processing quality. Tannic acid (TA) consisting of a central glucose unit and ten gallic acid molecules is a phenolic acid that improves the processing quality. However, the underlying mechanism of TA's improvement remains largely unknown. Here, we showed that TA's improving effects on gluten aggregation, dough-mixing and bread-making properties were directly associated with the kinds of HMW-GS expressed in wheat seeds in HMW-GS near-isogenic lines (NILs). We established a biochemical framework, elucidated the additive effects of HMW-GS-TA interaction and discovered that TA cross-linked specifically with wheat glutenins but not gliadins, and reduced gluten surface hydrophobicity and SH content depending on the kinds of expressed HMW-GS in the wheat seeds. We also demonstrated that hydrogen bonds play an essential role in TA-HMW-GS interactions and improvement of wheat processing quality. Additionally, the effects of TA on the antioxidant capacity and on nutrient (protein and starch) digestibility were also investigated in the NILs of HMW-GS. TA increased antioxidant capacity but did not affect the digestion of starches and proteins. Our results revealed that TA more effectively strengthened wheat gluten in the presence of more HMW-GS kinds, highlighting TA's potential as an improver toward healthy and quality bread and demonstrating that manipulating hydrogen bonds was a previously overlooked approach to improve wheat quality.

Stability of starch-proanthocyanidin complexes to in-vitro amylase digestion after hydrothermal processing

Proanthocyanidins (PA) form poorly digestible complexes with starch. The study examined amylase degradation mechanism and hydrothermal stability of starch-PA complexes. Sorghum-derived PA was complexed with wheat starch, reconstituted into flour (10% gluten added) and processed into crackers and pancakes. In vitro digestion profile of the complexes and products were characterized. The starch-PA complexes retained more (34-84%) fragments with degree of polymerization (DP) > 6,000 after 120 min digestion than controls (0-21%). Debranching further revealed higher retention of DP 11 - 30 chains in the digested starch-PA complexes than controls, suggesting amylopectin complexation contributed to reduced starch digestion. Starch-PA complexes retained reduced digestibility (50-56% higher resistant starch vs controls) in the cracker, but not pancake model. However, removing gluten from the pancake formulation restored the reduced digestibility of the starch-PA complexes. The starch-PA complexes are stable to hydrothermal processing, but can be disrupted by hydrophobic gluten proteins under excess moisture conditions.

Effects of HMW-GSs at Glu-B1 locus on starch-protein interaction and starch digestibility during thermomechanical processing of wheat dough

BACKGROUND

The composition of glutenin protein significantly affects protein-starch interactions and starch digestion characteristics in wheat dough matrices. To elucidate the effects of high molecular weight glutenin subunits at the Glu-B1 locus on dough processing quality, the detailed structural changes of protein, starch, and their complexes were compared in Mixolab dough samples of two near isogenic lines 7 + 8 and 7 + 9.

RESULTS

The results showed that the degree of protein aggregation increased continuously during dough processing, as did the destruction and rearrangement of the gluten network. Compared to 7 + 8, the stronger and more stable protein network formed in 7 + 9 dough induced intensive interactions between protein and starch, primarily through hydrogen bonds and isomeric glycosidic bonds. In 7 + 9 dough, the more compact and extensive protein-starch network significantly inhibited starch gelatinization during dough pasting, while during the dough cooling stage [from C4 (82.8 °C) to C5 (52.8 °C)], more protein-starch complexes composed of monomeric proteins and short-chain starch were generated, which remarkably inhibited starch retrogradation. All protein-starch interactions in the 7 + 9 dough improved the starch digestion resistance, as reflected by the high content of resistant starch.

CONCLUSION

The more extensive and intensive protein-starch interactions in the 7 + 9 dough inhibited the gelatinization and enzymatic hydrolysis of starch, thereby producing more slowly digestible starch and resistant starch. These findings demonstrate the feasibility of optimizing the texture and digestibility of wheat-based food products by regulating the behavior and interactions of proteins and starch during dough processing. © 2022 Society of Chemical Industry.

Sorghum in foods: Functionality and potential in innovative products

Sorghum grain is a staple food for about 500 million people in 30 countries in Africa and Asia. Despite this contribution to global food production, most of the world's sorghum grain, and nearly all in Western countries, is used as animal feed. A combination of the increasingly important ability of sorghum crops to resist heat and drought, the limited history of the use of sorghum in Western foods, and the excellent functional properties of sorghum grain in healthy diets, suggests a greater focus on the development of new sorghum-based foods. An understanding of the structural and functional properties of sorghum grain to develop processes for production of new sorghum-based foods is required. In this review, we discuss the potential of sorghum in new food products, including sorghum grain composition, the functional properties of sorghum in foods, processing of sorghum-based products, the digestibility of sorghum protein and starch compared to other grains, and the health benefits of sorghum. In the potential for sorghum as a major ingredient in new foods, we suggest that the gluten-free status of sorghum is of relatively minor importance compared to the functionality of the slowly digested starch and the health benefits of the phenolic compounds present.

Starch-protein interaction effects on lipid metabolism and gut microbes in host

The purpose of this experiment was to investigate the effects of different starch and protein levels on lipid metabolism and gut microbes in mice of different genders. A total of 160 male mice were randomly assigned to sixteen groups and fed a 4 × 4 Latin square design with dietary protein concentrations of 16, 18, 20, and 22%, and starch concentrations of 50, 52, 54, and 56%, respectively. The results of the study showed that different proportions of starch and protein had obvious effects on the liver index of mice, and there was a significant interaction between starch and protein on the liver index (p = 0.005). Compared with other protein ratio diets, 18% protein diet significantly increased the serum TBA concentration of mice (p < 0.001), and different starch ratio diets had no effect on serum TBA concentration (p = 0.442). It was proved from the results of ileal tissue HE staining that the low protein diet and the low starch diet were more favorable. There was a significant interaction between diets with different starch and protein levels on Bacteroidetes, Firmicutes and Proteobacteria abundance in feces of mice (p < 0.001). Compared with 16 and 18% protein ratio diets, both 20 and 22% protein diets significantly decreased the Parabacteroides and Alistipes abundance in feces of mice (p < 0.05), and 52% starch ratio diet significantly decreased the Parabacteroides and Alistipes abundance than 50% starch ratio diet of mice (p < 0.05). There was a significant interaction between diets with different starch and protein levels on Parabacteroides (p = 0.014) and Alistipes (p = 0.001) abundance in feces of mice. Taken together, our results suggest that a low protein and starch diet can alter lipid metabolism and gut microbes in mice.

Degradation of Hybrid Drug Delivery Carriers with a Mineral Core and a Protein–Tannin Shell under Proteolytic Hydrolases

Hybrid carriers with the mineral CaCO₃/Fe₃O₄ core and the protein–tannin shell are attractive for drug delivery applications due to reliable coupling of anticancer drugs with protein–tannin complex and the possibility of remote control over drug localization and delivery by the external magnetic field. This study aims to elucidate the mechanisms of drug release via enzymatic degradation of a protein–tannin carrier shell triggered by proteolytic hydrolases trypsin and pepsin under physiological conditions. To do this, the carriers were incubated with the enzyme solutions in special buffers to maintain the enzyme activity. The time-lapse spectrophotometric and electron microscopy measurements were carried out to evaluate the degradation of the carriers. It was established that the protein–tannin complex demonstrates the different degradation behavior depending on the enzyme type and buffer medium. The incubation in trypsin solution mostly resulted in the protein shell degradation. The incubation in pepsin solution did not affect the protein component; however, the citric buffer stimulates the degradation of the mineral core. The presented results allow for predicting the degradation pathways of the carriers including the release profile of the loaded cargo under physiological conditions. The viability of 4T1 breast cancer cells with mineral magnetic carriers with protein–tannin shells was investigated, and their movement in the fields of action of the permanent magnet was shown.

Potential food applications of sorghum (Sorghum bicolor) and rapid screening methods of nutritional traits by spectroscopic platforms

Sorghum is a drought-resistant crop widely spread in tropical regions of the American, African, and Asian continents. Sorghum flour is considered the main alternative for wheat flour, and it exhibits gluten-free nature. Generally, conventional wet chemical methods are used to analyze the nutritional profile of sorghum. Since many sorghum plants are available in breeding grounds, the application of conventional methods has limitations due to high cost and time consumption. Therefore, rapid screening protocols have been introduced as nondestructive alternatives. The current review highlights novel and portable devices that can be used to analyze the nutritional composition, color parameters, and pest resistance. Sorghum is often a traditional food item with minimal processing, and the review elaborates on emerging food applications and feasible food product developments from sorghum. The demand for gluten-free products has been rapidly increasing in developed countries. In order to develop food products according to market requirements, it is necessary to screen high-quality sorghum plants. Rapid analysis techniques effectively select the best sorghum types, and the novel tools have outperformed existing conventional methods.

Impact of condensed tannin interactions with grain proteins and non-starch polysaccharides on batter system properties

Proanthocyanidins (PA) cross-link wheat gluten proteins and dramatically enhance batter viscosity; PA could similarly affect related grains. This study aimed to determine PA effect on viscosity and pasting properties of barley, rye, and oat flours, and the relative contributions of PA interactions with proteins and non-starch polysaccharides (NSP). PA significantly increased batter viscosity, stability, and RVA peak viscosity in rye and barley flours (2.8× and 1.2×, respectively). Interestingly, viscosity peaked distinctively ~75 °C in PA-treated rye and barley flours, and their isolated protein-starch systems, indicating prolamins unravelled and complexed with PA during heating. Oat was largely unaffected by PA, likely because of its protein composition. Furthermore, water-soluble rye NSP and arabinoxylans, but not barley β-glucans, significantly increased starch pasting viscosity with PA; oxidative gelation was not a factor. Thus, rye flour viscosity dramatically increased through interactive effects of PA on rye proteins and NSP, which could expand its food applications.

Bioactive Peptides and Dietary Polyphenols: Two Sides of the Same Coin

The call for health-promoting nutraceuticals and functional foods containing bioactive compounds is growing. Among the great diversity of functional phytochemicals, polyphenols and, more recently, bioactive peptides have stood out as functional compounds. The amount of an ingested nutrient able to reach the bloodstream and exert the biological activity is a critical factor, and is affected by several factors, such as food components and food processing. This can lead to unclaimed interactions and/or reactions between bioactive compounds, which is particularly important for these bioactive compounds, since some polyphenols are widely known for their ability to interact and/or precipitate proteins/peptides. This review focuses on this important topic, addressing how these interactions could affect molecules digestion, absorption, metabolism and (biological)function. At the end, it is evidenced that further research is needed to understand the true effect of polyphenol-bioactive peptide interactions on overall health outcomes.

Effects of edible plant polyphenols on gluten protein functionality and potential applications of polyphenol-gluten interactions

Expanding plant-based protein applications is increasingly popular. Polyphenol interactions with wheat gluten proteins can be exploited to create novel functional foods and food ingredients. Polyphenols are antioxidants, thus generally decrease gluten strength by reducing disulfide cross-linking. Monomeric polyphenols can be used to reduce dough mix time and improve flexibility of the gluten network, including to plasticize gluten films. However, high-molecular-weight polyphenols (tannins) cross-link gluten proteins, thereby increasing protein network density and strength. Tannin-gluten interactions can greatly increase gluten tensile strength in dough matrices, as well as batter viscosity and stability. This could be leveraged to reduce detrimental effects of healthful inclusions, like bran and fiber, to loaf breads and other wheat-based products. Further, the dual functions of tannins as an antioxidant and gluten cross-linker could help restructure gluten proteins and improve the texture of plant-based meat alternatives. Tannin-gluten interactions may also be used to reduce inflammatory effects of gluten experienced by those with gluten allergies and celiac disease. Other potential applications of tannin-gluten interactions include formation of food matrices to reduce starch digestibility; creation of novel biomaterials for edible films or medical second skin type bandages; or targeted distribution of micronutrients in the digestive tract. This review focuses on the effects of polyphenols on wheat gluten functionality and discusses emerging opportunities to employ polyphenol-gluten interactions.

Factors Influencing Zein-Whole Sorghum Flour Dough Formation and Bread Quality

Zein is known to able to form viscoelastic dough with wheat-like properties under certain conditions. Several studies have been conducted to explain the mechanism behind this ability and to improve the functionality and end-use quality of zein-based dough systems. However, most of this research has been conducted using zein in combination with isolated starches or high-starch flours. To investigate the production of additional zein-whole sorghum flour breads, experiments were conducted to determine factors impacting zein-whole sorghum flour dough and bread quality. Optimizing water levels, using defatted zein and/or sorghum flour, and increasing zein content in dough formulas were investigated as initial formulation steps. Of these factors, increasing zein content from 20% to 30% (flour weight basis) had the greatest impact, resulting in stronger zein-based dough and improved bread quality. Additives and zein treatments shown to impact zein functionality were then investigated for their effect of zein-whole sorghum flour breads. Mixing zein and whole sorghum flour with 0.5% hydrogen peroxide, 5% ethanol, or 3% hydroxypropyl methylcellulose resulted in improved dough strength and bread quality. Breads made from whole white sorghum flour had improved quality compared to zein-based breads made with black or high-tannin whole sorghum flour. PRACTICAL APPLICATION: Zein is known to be able to form wheat-like dough when mixed under the right conditions. Most of the research on zein-based dough and food products has used high-starch flours. This project investigated optimizing the production of zein-whole sorghum flour dough and bread as an alternative. Increasing the zein content in the formula and using additives including ethanol and HPMC produced breads from zein-whole sorghum flour that were like those made with zein and pure starch.

Rapid and Noninvasive Typing and Assessment of Nutrient Content of Maize Kernels Using a Handheld Raman Spectrometer

To thrive as a global civilization, food production must meet the demands of our ever-growing population. There are more than a billion people on the planet suffering from malnutrition through poor quality or lack of food. Nutrient content of food can be determined by a variety of methods, which have issues such as slow analysis or sample destruction. Near-infrared (NIR) spectroscopy is a long-standing alternative to these methods. In this work, we demonstrated that Raman spectroscopy (RS), another spectroscopic method, can also be used to assess the nutrient content of maize (Zea mays), one of the most widely cultivated grains in the world. Using a handheld Raman spectrometer, we predicted the content of carbohydrates, fibers, carotenoids, and proteins in six different varieties of maize. This analysis requires only a single maize kernel and is fast (1s), portable, noninvasive, and nondestructive. Moreover, we showed that RS in combination with chemometric methods can be used for highly accurate (approximately 90%) spectroscopic typing of maize, which is important for plant breeders and farmers. Finally, we demonstrate that Raman-based approach is as accurate as NIR analysis. These findings suggest that portable Raman systems can be used on combines and grain elevators for autonomous control of grain quality.

Liquid state fermentation vinegar enriched with catechin as an antiglycative food product

Catechin, a natural antiglycative agent, was incorporated into fermented vinegar, and has high potential to lower the risk of diabetes. In this study, vinegar containing 5% catechin as a substrate for acetous fermentation significantly inhibited the formation of total fluorescent advanced glycation end-products (AGEs), as well as N^ε-(carboxymethyl)lysine (CML)/N^ε-(carboxyethyl)lysine (CEL), especially when added during acetic fermentation. Further study proved that catechin could not only significantly suppress the increase of blood glucose levels, but also inhibit α-amylase, α-glucosidase and β-glucosidase strongly with IC₅₀ values of 0.533 mg mL^-1, 0.307 mg mL^-1 and 0.413 mg mL^-1, respectively. Moreover, 32 volatile compounds were finally identified by headspace solid phase microextraction gas chromatography-mass spectrometry (HSPM-GC-MS) and electronic nose. The flavor of the catechin-vinegars, which possess relatively high ester and low acid contents, was superior to that of traditional vinegar. Therefore, it was helpful to use catechin as a functional food ingredient in vinegar to prevent AGE-associated diseases and alleviate postprandial hyperglycemia, through limiting the digestion of starch and inhibiting the uptake of glucose. Meanwhile, the pleasant flavor and safety of catechin-vinegar were better than traditional vinegar, which represents prominent value to attract consumers.

Complementary effects of cereal and pulse polyphenols and dietary fiber on chronic inflammation and gut health

Cereal grains and grain pulses are primary staples often consumed together, and contribute a major portion of daily human calorie and protein intake globally. Protective effects of consuming whole grain cereals and grain pulses against various inflammation-related chronic diseases are well documented. However, potential benefits of combined intake of whole cereals and pulses beyond their complementary amino acid nutrition is rarely considered in literature. There is ample evidence that key bioactive components of whole grain cereals and pulses are structurally different and thus may be optimized to provide synergistic/complementary health benefits. Among the most important whole grain bioactive components are polyphenols and dietary fiber, not only because of their demonstrated biological function, but also their major impact on consumer choice of whole grain/pulse products. This review highlights the distinct structural differences between key cereal grain and pulse polyphenols and non-starch polysaccharides (dietary fiber), and the evidence on specific synergistic/complementary benefits of combining the bioactive components from the two commodities. Interactive effects of the polyphenols and fiber on gut microbiota and associated benefits to colon health, and against systemic inflammation, are discussed. Processing technologies that can be used to further enhance the interactive benefits of combined cereal-pulse bioactive compounds are highlighted.

Persimmon Tannin Decreased the Glycemic Response through Decreasing the Digestibility of Starch and Inhibiting α-Amylase, α-Glucosidase, and Intestinal Glucose Uptake

Regulation of postprandial blood glucose levels is an effective therapeutic proposal for type 2 diabetes treatment. In this study, the effect of persimmon tannin on starch digestion with different amylose levels was investigated both in vitro and in vivo. Oral administration of persimmon tannin-starch complexes significantly suppressed the increase of blood glucose levels and the area under the curve (AUC) in a dose-dependent manner compared with starch treatment alone in an in vivo rat model. Further study proved that persimmon tannin could not only interact with starch directly but also inhibit α-amylase and α-glucosidase strongly, with IC₅₀ values of 0.35 and 0.24 mg/mL, separately. In addition, 20 μg/mL of persimmon tannin significantly decreased glucose uptake and transport in Caco-2 cells model. Overall, our data suggested that persimmon tannin may alleviate postprandial hyperglycemia through limiting the digestion of starch as well as inhibiting the uptake and transport of glucose.

Interaction mechanisms of condensed tannins (proanthocyanidins) with wheat gluten proteins

Proanthocyanidins (PA) crosslink wheat gluten, increasing its polymer size and strength. However, mechanisms behind these interactions are unknown. This study used PA of different MW profiles (mean degree of polymerization 8.3 and 19.5) to investigate how PA polymerize gluten. The higher MW PA had greater binding affinity for both glutenins and gliadins than lower MW PA, whereas both PA precipitated glutenins more efficiently than gliadins. The PA preferentially bound the largest of the protein fractions available: high MW glutenin subunits (HMW-GS) over low MW-GS, and ω-gliadins over α- and γ-gliadins. Furthermore, within the HMW-GS, PA bound more of the larger x-type than the smaller y-type. Proanthocyanidins reduced gluten solubility in urea and decreased surface hydrophobicity of glutenins, but not gliadins. The PA appear to preferentially crosslink HMW-GS via hydrophobic interactions and hydrogen bonding, whereas their interaction with gliadins is dominated by hydrogen bonding and is relatively weaker.

Effect of Condensed Tannin Profile on Wheat Flour Dough Rheology

Proanthocyanidins (PA) cross-link proteins and could expand wheat gluten functionality; however, how the PA MW or gluten profile affect these interactions is unknown. Effect of PA MW profile (sorghum versus grape seed PA) on dough rheology of high versus low insoluble polymeric protein (IPP) wheat flour was evaluated using mixograph, large (TA.XT2i) and small (HAAKE Rheostress 6000) deformation rheometry. Sorghum PA (93% polymeric) more effectively (p < 0.05) strengthened both glutens than grape seed PA (45% polymeric), without reducing gluten extensibility. These effects were higher in low IPP (weak gluten) flour, e.g., sorghum PA doubled IPP, increased mix time by 75%, dough elasticity by 82%, and peak angle by 17° versus control. Grape seed PA increased IPP by 75% and elasticity by 36%, but reduced peak angle by 15°, indicating reduced mixing tolerance. Sorghum PA, but not grape seed PA, increased (p < 0.05) all above parameters in high IPP dough. Polymeric PA more effectively strengthened gluten than oligomeric PA, likely via more efficient protein cross-linking to overcome strong antioxidant effect of PA. High MW PA may be useful natural gluten strengtheners for diverse applications.

Polymeric tannins significantly alter properties and in vitro digestibility of partially gelatinized intact starch granule

Excess calorie intake is a growing global problem. This study investigated effect of complexing partially gelatinized starch with condensed tannins on in vitro starch digestibility. Extracts from tannin and non-tannin sorghum, and cellulose control, were reacted with normal and waxy maize starch in 30% (30E) and 50% ethanol (50E) solutions at 70°C/20min. More tannins complexed with the 30E than 50E starches (mean 6.2 vs 3.5mg/g, respectively). In the 30E treatments, tannins significantly increased crystallinity, pasting temperature, peak viscosity, and slow digesting starch (from 100 to 274mg/g) in normal, but not waxy starch, suggesting intragranular cross-linking with amylose. Tannins doubled resistant starch (RS) to approx. 300mg/g in both starches. In 50E treatments, tannins made both maize starches behave like raw potato starch (>90% RS), suggesting granule surface interactions dominated. Non-tannin treatments generally behaved similar to cellulose. Condensed tannins could be used to favorably alter starch digestion profile.