Starch digestion in intact pulse cotyledon cells depends on the extent of thermal treatment

Influence of salts adopted in soaking treatments on the pulse cell wall matrix and in vitro digestion kinetics of starch

Starch is the major component of pulse cotyledons and a primary energy source in the human diet. Its digestion is influenced by intrinsic structure and processing-induced changes at cellular level. This study investigated the effects of monovalent, divalent, and trivalent salts on cell-wall structure and in vitro digestion properties of intracellular starch. Whole peas were soaked in salt-solutions with pH ranging from highly-acidic (1.5-4.5) to alkaline (10-11) and cooked cotyledon cells were isolated. Alkaline salt treatment enhanced water absorption, cell separation, yield, starch digestion, and fluorescence, while reduced particle size, galacturonic acid, protein content, and gelatinization temperatures compared to slightly-acidic salt treatments. In contrast, highly-acidic salt treatments caused slight cell rupture, reduced water absorption, yield, and nutritional content but increased starch crystallinity, gelatinization temperatures, and digestion with increased fluorescence. These findings show that salt-induced pH modulation can regulate starch digestion, providing insights into dietary management and metabolic health.

Influence of Thermal Processing on In Vitro Starch Digestibility in Cereal-Based Infant Foods

Early-life nutrition is crucial for healthy infant development. This study explored the effects of high-temperature (30 min, 121 °C) and high-humidity treatments on the starch properties and digestibility of infant purees made from wheat, rice, and maize. Purees were prepared using whole grains (WGs), whole grain flours (WGFs), and flour suspensions (FSs) subjected to thermal treatment. Untreated whole grain samples from each cereal served as controls. Samples were analyzed for microstructure, thermal properties, viscosity, and starch digestibility. Microstructural analysis revealed partial to complete loss of amyloplast birefringence, particularly in FS. The thermal treatment reduced peak viscosity in WGs, WGFs, and FSs. Also, the flour suspensions showed lower thermal stability and a phytic acid content reduction of 30%. In vitro digestion revealed a significant reduction in total hydrolyzed starch (THS) in wheat- (27.8 g/100 g starch) and maize- (11.3 g/100 g starch) WG purees compared to controls. In contrast, WGF purees showed significant increases in THS: 29% (wheat), 70% (rice), and 92% (maize). FS purees also showed significant increases in THS (57.4, 39.3, and 45.4 g/100 g starch for wheat, rice, and maize, respectively), alongside a decrease in resistant starch. In conclusion, thermal treatment modulates starch digestibility and viscosity properties in a cereal-dependent manner, offering a potential approach to optimize infant nutrition.

Structural barriers governing starch digestibility in intact highland barley cells: A closer insight from cell wall and protein matrix

The endosperm cell structure plays an important role in starch digestion. This study aimed to evaluate the effects of the structural properties of the cell wall and protein matrix on starch digestibility in intact cells isolated from the endosperm of highland barley. Damaged cells with different degree of cell wall degradation were obtained by controlling the time of β-glucanase hydrolysis of isolated cells. Intact cells exhibited the lowest starch digestibility (61.80 %) and gelatinization enthalpy change (3.55 J/g). As the degree of β-glucanase hydrolysis increased, the starch digestibility of damaged cells markedly increased and was close to that of mechanically crushed flour. Penetration of amylase-sized fluorescent probes showed that the probes barely penetrated the raw and cooked cell walls, indicating that the cell wall strongly blocked the contact between amylase and starch. Additionally, the compound network formed by the protein matrix and expanded starch hindered probe diffusion. However, the starches in the cells with the greatest cell wall loss were fully digested after 6 h of digestion. Therefore, the cell wall, an effective structural barrier to amylase, mainly limits starch digestibility, whereas the protein matrix/network acts as a secondary barrier. This study provides new insights into the processing of slow-digested cereals.

The influence of pulse cell wall structure and cellular protein matrix on the in vitro digestion kinetics of starch: A dual encapsulation mechanism

The intrinsic characteristics and extrinsic processing of whole-pulse food modulate the starch digestion rate and extent. This study investigated the dual encapsulation mechanism of cell wall structure and protein matrix on the in vitro digestion properties of intracellular starch, using an isolated whole-pulse food model of intact pea cotyledon cells subjected to alkaline buffer and enzymatic treatments. Results showed that intact cells with the maximum protein matrix content (18.9 %) exhibited the lowest peak temperature (71.4 °C, uncooked and 58.1 °C, cooked), enthalpy change (3.4 J/g, uncooked and 2.0 J/g, cooked), relative crystallinity (11.6 %), and starch digestion rate (0.0248 min-1) and extent (11.9 %) compared to alkaline buffer and enzymatic treatments. Even after enzymatic treatment, cells with minimal protein matrix content (1.8 %) exhibited a starch digestion rate (0.0387 min-1) and extent (39.7 %), which were still lower than those of isolated starch (0.0480 min-1 and 56.8 %). These findings indicate that the protein matrix and cell walls act as a dual encapsulation system to slow starch hydrolysis. This provides a theoretical basis and technical guidance for developing low-glycemic whole-pulse foods.

In vitro simulated digestion and fermentation behaviors of polysaccharides from Pleurotus cornucopiae and their impact on the gut microbiota

This study investigated the physicochemical characteristics and fermentative behavior between original polysaccharides (PCPs) and polysaccharides extracted after microwave cooking (MPCPs) from Pleurotus cornucopiae during simulated digestion and fecal fermentation. The results revealed notable physicochemical differences between of PCPs and MPCPs. MPCPs exhibited a higher total carbohydrate content, with an increased proportion of glucose. Additionally, MPCPs showed a lower molecular weight (MW) and, a blue shift in Fourier transform infrared spectroscopy (FT-IR). Digestion has a minimal effect on the physicochemical and structural characteristics of PCPs and MPCPs. Within the first 6 h of fermentation, the gut microbiota showed significantly higher utilization of MPCPs. However, PCPs were consumed faster and surpassed MPCPs later. After 24 h, both PCPs and MPCPs were degraded and utilized by the gut microbiota, showing an increased abundance of Firmicutes and Bacteroidota. PCPs excelled in promoting beneficial gut microbiota, such as Phascolarctobacterium, Megamonas, and Bacteroides. Conversely, MPCPs demonstrated a stronger ability to inhibit the growth of harmful opportunistic pathogenic gut microbiota, such as Fusobacterium and Parasutterella. In addition, the content of acetic, propionic, and butyric acids increased significantly in both PCPs and MPCPs. These findings highlight the potential of Pleurotus cornucopiae polysaccharides as prebiotics for intestinal homeostasis.

Effects of black bean cell wall pectin by exogenous calcium ions: Insight into the metabolomics, physicochemical properties and anti-digestive capacity

In this work, the metabolomics, physicochemical and in vitro digestion properties of black beans influenced by different calcium ion solutions (0, 0.5 %, 1 %, and 2 %) were explored. The addition of calcium ions had a significant effect on the metabolic processing of black beans, including 16 differential metabolites and 4 metabolic pathways related to the cell wall. From the results of FT-IR and ICP-OES, it was confirmed that calcium ions can interact with COO- in non-methylated galacturonic acid in pectin to form calcium carboxylate strengthening the middle lamellae of the cell wall. Based on this mechanism, the soaked beans with an intact and dense cell structure were verified by the analyses of SEM and CLSM. Compared with other soaked beans, BB-2 exhibited lower cell permeability with electrical conductivity value decreased to 0.60 μs·cm-1. Additionally, BB-2 demonstrated slower digestion properties with digestion rate coefficient at 0.0020 min-1 and digestion extent only at 30.83 %, which is attributed to its increasingly compact cell wall and densely cellular matrix. This study illustrates the effect of calcium ions on the cellular structure of black beans, providing an effective process method for low glycemic index diets.

Salt adopted in soaking solution controls the yield and starch digestion kinetics of intact pulse cotyledon cells

Intact cellular powders have gained attention as a functional ingredient due to their lower glycemic response and potential benefits in colon. The isolation of intact cells in the laboratory and pilot plant settings is mainly achieved through thermal treatment with or without the use of limited salts. However, the effects of salt type and concentration on cell porosity, and their impact on the enzymic hydrolysis of encapsulated macro-nutrients such as starch, have been overlooked. In this study, different salt-soaking solutions were used to isolate intact cotyledon cells from white kidney beans. The use of Na₂CO₃ and Na₃PO₄ soaking treatments, with high pH (11.5-12.7) and high amount of Na ion (0.1, 0.5 M), greatly improved the yield of cellular powder (49.6-55.5 %), due to the solubilization of pectin through β-elimination and ion exchange. Intact cell walls serve as a physical barrier, significantly reducing the susceptibility of cell to amylolysis when compared to white kidney bean flour and starch counterparts. However, the solubilization of pectin may facilitate enzyme access into the cells by enlarging cell wall permeability. These findings provide new insights into the processing optimization to improve the yield and nutritional value of intact pulse cotyledon cells as a functional food ingredient.

Variation in structural and in vitro starch digestion of pulse cotyledon cells imposed by temperature-pressure-moisture combinations

Starch digestibility in whole pulses is affected by food structural characteristics, which in turn can be modulated by processing methods. In present study, high-pressure steam (HPS) and hydrothermal treatment (HT) with different moisture content were applied to clarify the mechanisms of processing variables affecting in vitro starch digestibility in pulse cells. Based on thermal and X-ray results, the relative crystallinity of cells decreased after HPS and HT treatments. However, HPS-treated cells under higher (>50%) moisture content showed insignificant discrepancies in crystallinity than HT samples. Starch digestion in HPS-treated cells increased with higher moisture content but was still lower than in HT samples. Results of FITC-dextran diffusion and methyl esterification of cell walls indicated that cells with higher wall permeability exhibited relatively higher starch digestibility. This study suggests that the enzyme susceptibility to starch in cells is dominantly influenced by cell wall structure, which could be optimized through processing variables.

Effects of in vitro simulated digestion and fecal fermentation of polysaccharides from straw mushroom (Volvariella volvacea) on its physicochemical properties and human gut microbiota

Herein, the fermentation and digestion behavior of Volvariella volvacea polysaccharide (VVP) were examined through the in vitro simulation experiment. The results revealed that succeeding the simulated salivary gastrointestinal digestion, the molecular weight of VVP was reduced by only 8.9 %. In addition, the reducing sugar, uronic acid, monosaccharide composition and Fourier transform infrared spectroscopy characteristics of VVP did not change significantly, which indicate that saliva-gastrointestinal could not digest VVP. However, 48 h of fecal fermentation of VVP dramatically reduced its molecular weight by 40.4 %. Furthermore, the molar ratios of the monosaccharide composition altered considerably due to the degradation of VVP by microorganisms and the metabolysis into different short-chain fatty acids (SCFAs). Meanwhile, the VVP also raised the proportion of Bacteroidetes to Firmicutes and promoted the proliferation of some beneficial bacteria including Bacteroides and Phascolarctobacterium, whereas it inhibited the growth of unfavorable bacteria such as Escherichia-shigella. Therefore, VVP has the potential to have a positive influence on health and hinder diseases by improving the intestinal microbial environment. These findings provide a theoretical foundation to further develop Volvariella volvacea as a healthy functional food.

Effects of in vitro digestion and fecal fermentation on physico-chemical properties and metabolic behavior of polysaccharides from Clitocybe squamulosa

The aim of this study was to establish a human digestion model in vitro to explore the degradation characteristics of a novel high-purity polysaccharide from Clitocybe squamulosa (CSFP2). The results showed that the content of reducing sugars (C_R ) of CSFP2 increased from 0.13 to 0.23 mg/mL, the molecular weight (Mw) of CSFP2 decreased significantly during the saliva-gastrointestinal digestion. The constituent monosaccharides of CSFP2, including galactose, glucose, and mannose, were stable during in vitro digestion, but their molar ratios were changed from 0.023: 0.737: 0.234 to 0.496: 0.478: 0.027. The surface of CSFP2 changes from a rough flaky structure to a scattered flocculent or rod-shaped structure after the gastrointestinal digestion. However, the apparent viscosity of CSFP2 was overall stable during in vitro digestion. Moreover, CSFP2 still maintains its strong antioxidant capacity after saliva-gastrointestinal digestion. The results showed that CSFP2 can be partially decomposed during digestion. Meanwhile, some physico-chemical properties of the fermentation broth containing CSFP2 changed significantly after gut microbiota fermentation. For example, the pH value (from 8.46 to 4.72) decreased significantly (p < 0.05) after 48 h of fermentation. the OD ₆₀₀ value increased first and then decreased (from 2.00 to 2.68 to 1.32) during 48-h fermentation. In addition, CSFP2 could also increase the amounts of short-chain fatty acids (SCFAs) (from 5.5 to 37.15 mmol/L) during fermentation (in particular, acetic acid, propionic acid, and butyric acid). Furthermore, the relative abundances of Bacteriodes, Bifidobacterium, Catenibacterium, Lachnospiraceae_NK4A136_group, Megasphaera, Prevotella, Megamonas, and Lactobacillus at genus level were markedly increased with the intervention of CSFP2. These results provided a theoretical basis for the further development of functional foods related to CSFP2.

How Cooking Time Affects In Vitro Starch and Protein Digestibility of Whole Cooked Lentil Seeds versus Isolated Cotyledon Cells

Lentils are sustainable sources of bioencapsulated macronutrients, meaning physical barriers hinder the permeation of digestive enzymes into cotyledon cells, slowing down macronutrient digestion. While lentils are typically consumed as cooked seeds, insights into the effect of cooking time on microstructural and related digestive properties are lacking. Therefore, the effect of cooking time (15, 30, or 60 min) on in vitro amylolysis and proteolysis kinetics of lentil seeds (CL) and an important microstructural fraction, i.e., cotyledon cells isolated thereof (ICC), were studied. For ICC, cooking time had no significant effect on amylolysis kinetics, while small but significant differences in proteolysis were observed (p < 0.05). In contrast, cooking time importantly affected the microstructure obtained upon the mechanical disintegration of whole lentils, resulting in significantly different digestion kinetics. Upon long cooking times (60 min), digestion kinetics approached those of ICC since mechanical disintegration yielded a high fraction of individual cotyledon cells (67 g/100 g dry matter). However, cooked lentils with a short cooking time (15 min) showed significantly slower amylolysis with a lower final extent (~30%), due to the presence of more cell clusters upon disintegration. In conclusion, cooking time can be used to obtain distinct microstructures and digestive functionalities with perspectives for household and industrial preparation.

Comparative study on the structural and in vitro digestion properties of starch within potato parenchyma cells under different cooking methods

To study the effects of cooking methods on the structure and digestion changes of starch encapsulated by cellular structure, intact potato parenchyma cells were successfully isolated and then subjected to different domestic cooking methods, including baking, frying, boiling, and autoclaving. The morphology, crystalline structure, thermal properties, and in vitro starch digestibility of cooked cell samples were investigated. Our results indicated that potato cell walls remained intact and performed as physical barriers preventing the diffusion/absorption of α-amylase to intracellular starch substrates after baking or frying treatment. However, boiling or autoclaving treatment destroyed cell wall structure, and the disrupted cellular structure reduced the digestion rate, likely by inhibiting diffusion of amylase through a weakened cell wall barrier, but could not lower the final digestion extent when compared to the pure starch. These findings suggested that potato products with lower glycemic index can be obtained by baking or frying treatment.

Lactoferrin Inhibits the Development of T2D-Induced Colon Tumors by Regulating the NT5DC3/PI3K/AKT/mTOR Signaling Pathway

Although increasing evidence shows the association between type 2 diabetes (T2D) and colorectal cancer, the related mechanism remains unclear. This study examined the suppressive effect of lactoferrin (LF) on the development of T2D-induced colon cancer. First, a co-cultured cell model consisting of NCM460 and HT29 cells was constructed to mimic the progression of T2D into colon cancer. The migration ability of NCM460 cells increased significantly (p < 0.05) after cultivation in HT29 cell medium (high glucose), while LF suppressed the progression of T2D to colon cancer by regulating the 5′-nucleotidase domain-containing 3 (NT5DC3) protein and the PI3K/AKT/mTOR signaling pathway in diabetic BALB/c mice and in cell models. A mutation assay of the phosphorylation site in the NT5DC3 protein and a surface plasmon resonance (SPR) protein binding test were performed to further ascertain a mechanistic link between LF and the NT5DC3 protein. The results indicated that LF specifically bound to the NT5DC3 protein to activate its phosphorylation at the Thr6 and Ser11 sites. Next, metabolic-specific staining and localization experiments further confirmed that LF acted as a phosphate donor for NT5DC3 protein phosphorylation by regulating the downstream metabolic pathway in T2D-induced colon tumors, which was specifically accomplished by controlling Thr6/Ser11 phosphorylation in NT5DC3 and its downstream effectors. These data on LF and NT5DC3 protein may suggest a new therapeutic strategy for cancer prevention, especially in T2D patients susceptible to colon cancer.

Dietary compounds slow starch enzymatic digestion: A review

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

Nonconventional Hydrocolloids’ Technological and Functional Potential for Food Applications

This review aims to study the alternatives to conventional industrial starches, describing uncommon sources along with their technological characteristics, processing, and performance on food products. Minor components remaining after extraction play an important role in starch performance despite their low percentage, as happens with tuber starches, where minerals may affect gelatinization. This feature can be leveraged in favor of the different needs of the food industry, with diversified applications in the market being considered in the manufacture of both plant and animal-based products with different sensory attributes. Hydrocolloids, different from starch, may also modify the technological outcome of the amylaceous fraction; therefore, combinations should be considered, as advantages and disadvantages linked to biological origin, consumer perception, or technological performance may arise. Among water-based system modifiers, starches and nonstarch hydrocolloids are particularly interesting, as their use reaches millions of sales in a multiplicity of specialties, including nonfood businesses, and could promote a diversified scheme that may address current monocrop production drawbacks for the future sustainability of the food system.

Utilizing Hydrothermal Processing to Align Structure and In Vitro Digestion Kinetics between Three Different Pulse Types

Processing results in the transformation of pulses’ structural architecture. Consequently, digestion is anticipated to emerge from the combined effect of intrinsic (matrix-dependent) and extrinsic (processed-induced) factors. In this work, we aimed to investigate the interrelated effect of intrinsic and extrinsic factors on pulses’ structural architecture and resulting digestive consequences. Three commercially relevant pulses (chickpea, pea, black bean) were selected based on reported differences in macronutrient and cell wall composition. Starch and protein digestion kinetics of hydrothermally processed whole pulses were assessed along with microstructural and physicochemical characteristics and compared to the digestion behavior of individual cotyledon cells isolated thereof. Despite different rates of hardness decay upon hydrothermal processing, the pulses reached similar residual hardness values (40 N). Aligning the pulses at the level of this macrostructural property translated into similar microstructural characteristics after mechanical disintegration (isolated cotyledon cells) with comparable yields of cotyledon cells for all pulses (41–62%). We observed that processing to equivalent microstructural properties resulted in similar starch and protein digestion kinetics, regardless of the pulse type and (prolonged) processing times. This demonstrated the capacity of (residual) hardness as a food structuring parameter in pulses. Furthermore, we illustrated that the digestive behavior of isolated cotyledon cells was representative of the digestion behavior of corresponding whole pulses, opening up perspectives for the incorporation of complete hydrothermally processed pulses as food ingredients.

How postharvest variables in the pulse value chain affect nutrient digestibility and bioaccessibility

Pulses are increasingly being put forward as part of healthy diets because they are rich in protein, (slowly digestible) starch, dietary fiber, minerals, and vitamins. In pulses, nutrients are bioencapsulated by a cell wall, which mostly survives cooking followed by mechanical disintegration (e.g., mastication). In this review, we describe how different steps in the postharvest pulse value chain affect starch and protein digestion and the mineral bioaccessibility of pulses by influencing both their nutritional composition and structural integrity. Processing conditions that influence structural characteristics, and thus potentially the starch and protein digestive properties of (fresh and hard-to-cook [HTC]) pulses, have been reported in literature and are summarized in this review. The effect of thermal treatment on the pulse microstructure seems highly dependent on pulse type-specific cell wall properties and postharvest storage, which requires further investigation. In contrast to starch and protein digestion, the bioaccessibility of minerals is not dependent on the integrity of the pulse (cellular) tissue, but is affected by the presence of mineral antinutrients (chelators). Although pulses have a high overall mineral content, the presence of mineral antinutrients makes them rather poorly accessible for absorption. The negative effect of HTC on mineral bioaccessibility cannot be counteracted by thermal processing. This review also summarizes lessons learned on the use of pulses for the preparation of foods, from the traditional use of raw-milled pulse flours, to purified pulse ingredients (e.g., protein), to more innovative pulse ingredients in which cellular arrangement and bioencapsulation of macronutrients are (partially) preserved.

Effects of Different Processing Methods and Internal Components on Physicochemical Properties and Glycemic Index of Adzuki Bean Powder

The estimated glycemic index (eGI) value of adzuki bean powder prepared by steamed cooking (SC), extruded cooking (EC) and roller cooking (RC) was studied comparatively. Results showed that RC had the highest eGI, with 80.1, and both EC and SC resulted in a lower eGI value of 70.0 and 49.7, respectively. Compared with the EC and RC methods, the SC method provided a more intact physical barrier for starch digestion, resulting in a less destroyed cell structure. As the essential components that form the cell wall, the study further investigated the effects of protein and fiber on physicochemical properties, in vitro starch digestibility and the eGI of adzuki bean powder processed with the SC method. Viscozyme and Protamax were used to obtain the deprotein and defiber samples. Results showed that the SC treatment with Viscozyme and Protamax, respectively, had significant effects on in vitro starch digestibility. The eGI of different samples were given as follows: steamed cooking adzuki bean powder (49.7) < deproteined adzuki bean powder (60.5) < defibered adzuki bean powder (83.1), which indicates that fiber may have a greater influence on the eGI than protein.

Pea cell wall integrity controls the starch and protein digestion properties in the INFOGEST in vitro simulation

The cell wall microstructure has been recognized to modulate the digestibility and bioaccessibility of nutrients in whole pulse foods, while the role of cell wall integrity is unclarified in the hydrolysis of intracellular nutrients during human gastrointestinal transit. Intact pea cells were isolated to prepare a series of cell wall integrity subjected to cooking and followed by the in vitro hydrolysis of starch and protein properties using the INFOGEST 2.0 in vitro simulation. Thermal properties showed that cell samples either in raw or cooked form with different wall integrity exhibited similar and higher starch gelatinization temperatures compared to the isolated starch counterpart. It was found that intact pea cells showed the limited hydrolysis extent of the maltose (16.2%) and NH2 (6.7%) compared to the damaged cells. In addition, intact cells also withheld the cell wall integrity throughout gastrointestinal digestion with minor rupture, and presented the higher protein molecular weight (70 kDa) in the SDS-PAGE profiles. Results suggested that the in vitro starch and protein digestion properties are modulated by the cell wall integrity, which may lead to lower glycemic response and open up the possibilities of designing health food products.

The impact of replacing wheat flour with cellular legume powder on starch bioaccessibility, glycaemic response and bread roll quality: A double-blind randomised controlled trial in healthy participants

The global rise in obesity and type 2 diabetes has generated significant interest in regulating the glycaemic impact of staple foods. Wheat breads (white or wholemeal) are popular staples, but have a high-glycaemic index, due to the highly digestible wheat starch. Reducing the glycaemic potency of white bread is challenging because the bread-making conditions are mostly conducive to starch gelatinisation. Cellular legume powders are a new source of type 1 resistant starch, where the starch is encapsulated by dietary fibre in the form of intact plant cell walls. The starch in these cell powders is less susceptible to gelatinisation and digestion than starch in conventional legume flours. However, legume cell resilience to baking conditions and the effects of this ingredient on glycaemic responses and product quality are unknown. Here we show that the integrity of cell wall fibre in chickpea powder was preserved on baking and this led to a ~40% reduction in in vivo glycaemic responses (iAUC120) to white bread rolls (~50 g available carbohydrate and 12 g wheat protein per serving) when 30% or 60% (w/w) of the wheat flour was replaced with intact cell powder. Significant reductions in glycaemic responses were achieved without adverse effects on bread texture, appearance or palatability. Starch digestibility analysis and microscopy confirmed the importance of cell integrity in attenuating glycaemic responses. Alternative processing methods that preserve cell integrity are a new, promising way to provide healthier low glycaemic staple foods; we anticipate that this will improve dietary options for diabetes care.

Effects of acid hydrolysis on the evolution of starch fine molecular structures and gelatinization properties

Effects of acid hydrolysis on amylose molecular structures and their relations to starch gelatinization properties were investigated. First-order kinetics models were applied to fit the evolution curve of starch chain-length and molecular size by acid hydrolysis treatment. Results showed that a single hydrolysis phase was involved in the degradation of waxy maize starch chains, while two distinct phases existed for the degradation of maize, high amylose maize and sago starch chains. The fast hydrolysis phase involved degradation of amylose chains with DP > ~300 and amylopectin long intra-cluster branches, while amylose chains with DP < ~300 was involved in the slow hydrolysis phase. Amylose molecules with DP ~ 300 were proposed to impact starch gelatinization properties by interaction with cut-off amylopectin double helices and formation of amylose crystallites/entanglements. This study could help food industry precisely control amylose molecular structures by acid hydrolysis treatment to develop starchy foods with desirable properties.

Cell wall permeability of pinto bean cotyledon cells regulate in vitro fecal fermentation and gut microbiota

Processing induced structural changes of whole foods for the regulation of the colonic fermentation rate and microbiota composition are least understood and often overlooked. In the present study, intact cotyledon cells from pinto beans were isolated as a whole pulse food model and subjected to a series of processing temperatures to modulate the structure, most dominantly the cell wall permeability. The cell wall permeability, observed with the diffusion of fluorescently labeled dextran (FITC-dextran), was increased as a function of the hydrothermal temperature, which is in line with the rise in the in vitro fecal fermentation rate and production of short-chain fatty acids (SCFAs) from the pinto bean cells. Further, the abundance of beneficial microbiota, such as Roseburia, Lachnospiraceae, Bacteroides, and Coprococcus, were significantly higher for cells processed at 100 °C compared to the 60 °C-treated ones. We conclude that cell wall provides an effective barrier for the microbial fermentation of intact cells. With an increase in cell wall permeability, microbes and/or microbial enzymes have easier access to intracellular starch for fermentation, leading to an increase in the production of metabolites and the abundance of beneficial microbes. Thus, desired colonic fermentation profiles can be achieved with the controlled processing of whole foods for enhanced gut health.