Digestible Starch Fraction Research Articles

A bootstrap approach for the reliable estimation of digestible starch fractions from digestograms

A bootstrap approach for the reliable estimation of digestible starch fractions from digestograms

Presence of digestible starch impacts in vitro fermentation of resistant starch.

Starch is an important energy source for humans. Starch escaping digestion in the small intestine will transit to the colon to be fermented by gut microbes. Many gut microbes express α-amylases that can degrade soluble starch, but only a few are able to degrade intrinsic resistant starch (RS), which is insoluble and highly resistant to digestion (≥80% RS). We studied the in vitro fermentability of eight retrograded starches (RS-3 preparations) differing in rapidly digestible starch content (≥70%, 35-50%, ≤15%) by a pooled adult faecal inoculum and found that fermentability depends on the digestible starch fraction. Digestible starch was readily fermented yielding acetate and lactate, whereas resistant starch was fermented much slower generating acetate and butyrate. Primarily Bifidobacterium increased in relative abundance upon digestible starch fermentation, whereas resistant starch fermentation also increased relative abundance of Ruminococcus and Lachnospiraceae. The presence of small fractions of total digestible starch (±25%) within RS-3 preparations influenced the fermentation rate and microbiota composition, after which the resistant starch fraction was hardly fermented. By short-chain fatty acid quantification, we observed that six individual faecal inocula obtained from infants and adults were able to ferment digestible starch, whereas only one adult faecal inoculum was fermenting intrinsic RS-3. This suggests that, in contrast to digestible starch, intrinsic RS-3 is only fermentable when specific microbes are present. Our data illustrates that awareness is required for the presence of digestible starch during in vitro fermentation of resistant starch, since such digestible fraction might influence and overrule the evalution of the prebiotic potential of resistant starches.

Designing a Specific Pretreatment on Corn Starch to Facilitate Enzymatic Rearrangement of Glycosidic Bonds for Efficiently Reducing Starch Digestibility.

Bacterial 1,4-α-glucan branching enzymes (GBEs) provide a viable strategy for glycosidic bond rearrangement in starch and regulation of its digestion rate. However, the exponential increase in paste viscosity during starch gelatinization has a detrimental effect on the catalytic action of GBEs, thereby limiting productivity and product performance. Here, we designed an enzymatic treatment on corn starch granules by the GBE from Rhodothermus obamensis STB05 (Ro-GBE) prior to the glycosidic bond rearrangement of gelatinized starch catalyzed using the GBE from Geobacillus thermoglucosidans STB02 (Gt-GBE). Specifically, a moderate amount of Ro-GBE was required for the pretreatment stage. The dual GBE modification process enabled the treatment of more concentrated starch slurry (up to 20%, w/w) and effectively reduced starch digestibility. The resulting product contained a rapidly digestible starch fraction of 66.0%, which was 11.4% lower than that observed in the single Gt-GBE-modified product. The mechanistic investigation showed that the Ro-GBE treatment promoted swelling and gelatinization of starch granules, reduced starch paste viscosity, and increased the mobility of water molecules in the starch paste. It also created a preferable substrate for Gt-GBE. These changes improved the transglycosylation efficiency of Gt-GBE. These findings provide useful guidance for designing an efficient process to regulate starch digestibility.

Molecular structure and characteristics of phytoglycogen, glycogen and amylopectin subjected to mild acid hydrolysis

The structure and properties of phytoglycogen and glycogen subjected to acid hydrolysis was investigated using amylopectin as a reference. The degradation took place in two stages and the degree of hydrolysis was in the following order: amylopectin > phytoglycogen > glycogen. Upon acid hydrolysis, the molar mass distribution of phytoglycogen or glycogen gradually shifted to the smaller and broadening distribution region, whereas the distribution of amyopectin changed from bimodal to monomodal shape. The kinetic rate constant for depolymerization of phytoglycogen, amylopectin, and glycogen were 3.45 × 10−5/s, 6.13 × 10−5/s, and 0.96 × 10−5/s, respectively. The acid-treated sample had the smaller particle radius, lower percentage of α-1,6 linkage as well as higher rapidly digestible starch fractions. The depolymerization models were built to interpret the structural differences of glucose polymer during acid treatment, which would provide guideline to improve the structure understanding and precise application of branched glucan with desired properties.

Non-conventional starches isolated from agronomic-improved beans (Phaseolus vulgaris L.): A study of their structure and physicochemical properties.

Non-conventional starch sources are promising alternative food ingredients. Different bean varieties with agronomic improvements are constantly being developed and cultivated in the North-western Argentinean region (NOA) to increase yields and obtain high-quality seeds. However, the main attributes of their starches have not been studied. In this work, starches from 4 agronomic-improved bean cultivars were isolated and their structure and physicochemical properties were evaluated. High-purity starches were obtained, as their low protein and ash contents showed. Starch granules presented smooth surfaces with spherical to oval shapes, with a marked "maltese cross" and heterogeneous sizes. Their amylose content revealed a mean value of 318 g.kg-1 and all presented resistant > slowly digestible > rapidly digestible starch fractions. Their FTIR spectra were almost similar and the X-ray diffraction analysis showed a CA- type pattern in all cases despite their different sources. Among thermal properties, Escarlata´ starch showed the lowest gelatinization peak temperature (69.5 °C) and Anahí´ starch the highest (71.3 °C). Starch´s pasting temperatures varied from 74.6 to 76.9 °C, whereas peak viscosity and final viscosity had a similar tendency, being Leales B30 < Anahí < Escarlata < Cegro 99/11-2 and Leales B30 < Anahí = Escarlata < Cegro 99/11-2, respectively. This study provides a basis for a better understanding of the characteristics of agronomic-improved NOA bean starches, enabling their use in product formulation as an alternative to starches from conventional sources. This article is protected by copyright. All rights reserved.

The effect of psyllium fiber on the in vitro starch digestion of steamed and roasted wheat based dough.

This study aimed to determine how the addition of psyllium fiber to steamed and roasted wheat-based flat dough pieces affected the in vitro starch digestibility. Wheat flour was replaced with 10% psyllium fiber in the preparation of fiber-enriched dough samples. Two distinct methods of heating were utilised: steaming (100 °C, 2 min & 10 min) and roasting (100 °C, 2 min & 250 °C, 2 min). Rapidly digestible starch (RDS) fractions reduced significantly in both steamed and roasted samples, whereas slowly digestible starch (SDS) fractions increased significantly only in samples roasted at 100 °C and steamed for 2 min. The roasted samples had a lower RDS fraction than the steamed samples only when fiber was added. This study demonstrated the effect of processing method, duration, temperature, formed structure, matrix and the addition of psyllium fiber on in vitro starch digestion by altering starch gelatinization, gluten network, and consequently enzyme access to substrates.

Stale bread waste recycling as ingredient for fresh oven-baked white bread: effects on dough viscoelasticity, bread molecular organization, texture, and starch digestibility.

Wasted food produced for human consumption is estimated at 33% globally, and bread is the food product with the highest percentage. There is an ongoing drive to reincorporate food waste still useful and safe into the production chain of food for human consumption. This work aims to contribute to the study of the feasibility of recycling stale bread waste flour (BWF) into fresh oven-baked white bread, by replacing 0, 20, 40, 60, 80, and 100 g/100 g of the wheat flour with BWF. Storage and loss moduli increased as the BWF content increased. The baked loaf exhibited decreased lightness and yellowness but increased redness. Increasing BWF contents produced decreased loaf volume and hardness but increased moisture content. Fourier-transform infrared analysis showed that the BWF addition induced important changes in the water, protein, and starch molecular organization. Therefore, starch digestibility showed reductions in both rapidly and slowly digestible starch fractions. Principal component analysis revealed that replacements of up 20 g/100 g can produce white bread with textural, colour, and starch digestibility characteristics like that of the control bread. The fresh oven-baked white bread variation produced by replacing 20 g/100 g of the wheat flour with BWF exhibited comparable colour, volume, texture, and starch digestibility features as a control bread did made with 0 g/100 BWF. Higher replacement percentages of wheat flour by stale BWF produced unsuitable drawbacks in the white bread characteristics, but those might be deemed as convenient in other types of bakery products. © 2023 Society of Chemical Industry.

Structural basis for rice starch multi-digestible fractions revealed by consecutive reaction kinetics model.

Starch-based foods (e.g. rice) usually contain multiple starch fractions with distinct digestion rate constants, although their nature is currently unknown. The present study applied the recently developed consecutive reaction kinetics model to fit the in vitro digestion curves for starch fractions deconvoluted from the overall digestograms to differentiate their binding and catalysis rates to starch digestive enzymes. The fitting parameters were then correlated with starch molecular structures obtained from published data to understand starch structural features determining the binding and catalytic rate constants. Binding and catalysis rates for the rapidly (RDF) and slowly digestible starch fraction (SDF) were controlled by distinct starch structural features. Typically, (i) the binding rate constant for RDF was negatively correlated with the amount of amylose short to intermediate chains, whereas it was positively correlated with the relative length of amylopectin intermediate chains; (ii) the catalysis rate constant for RDF was negatively correlated with the amount of amylose short to intermediate chains, relative length of amylose intermediate chains and amount of amylopectin long chains, whereas it was positively correlated with starch molecular size as well as relative length of amylopectin intermediate chains; (iii) and the catalysis rate constant for SDF was negatively correlated with the amount of amylopectin long chains, whereas it was positively correlated with starch molecular size. These results provide a better understanding of the nature of different starch digestible fractions and the development of foods such as rice with slow starch digestibility. © 2023 Society of Chemical Industry.

Definition of starch components in foods by first-order kinetics to better understand their physical basis

Starch-based foods frequently contain different starch digestible fractions, with distinct digestion rates and locations in human upper gastrointestinal tract. Understanding the physical basis for these starch components is critical for developing foods with low glycemic index (GI) values. Conducting first-order kinetics analysis has been able to extract information on starch digestion properties, with solid physical basis. However, there is currently no clear procedure in terms of defining different starch fractions by first-order kinetics analysis. This review proposes that starch-based foods can be categorized as structurally homogenous or heterogenous starch systems by fitting their starch digestograms to the first-order kinetics model, which are characterized by a single set or multiple sets of digestion rate constants and the fractions remaining undigested at long times during in vitro digestion. In line with starch hierarchical structures, it helps understand the structural origins for different starch components in foods, which can ultimately help the development of functional foods with low GI. Procedure to identify the starch fractions in starch-based foods to better understand their physical basis. SF is single fraction. RDF represents rapidly digestible starch fraction, while SDF represents slowly digestible starch fraction. • Starch-based foods often contain multiple starch fractions. • These foods can be defined as structurally homogeneous or heterogenous foods. • This definition helps the understanding of physical basis for starch digestibility.

Changes in Starch In Vitro Digestibility and Properties of Cassava Flour Due to Pulsed Electric Field Processing.

The research aimed to investigate the effect of pulsed electric field (PEF) treatment on cassava flour at mild intensities (1, 2, and 4 kV/cm) combined with elevated levels of specific energy input (250-500 kJ/kg). Influences on starch digestibility, morphological characteristics, birefringence, short-range order and thermal properties were evaluated. Application of PEF at energy input no greater than 250 kJ/kg had negligible influence on the different starch digestion fractions of cassava flour but raised the rapidly digestible starch fraction at a combined electric field strength &gt;1 kV/cm and energy input &gt;350 kJ/kg. Morphological evaluation revealed that at this PEF combination, cassava starch's external structure was consistently altered with swelling and disintegration, albeit some granules remained intact. Consequently, this led to disruption in the internal crystalline structure, supported by progressive loss of birefringence and significantly lower absorbance ratio at 1047/1022 cm-1. These physical and microstructural changes of the inherent starch promoted the shift in gelatinization temperatures to a higher temperature and reduced the gelatinization enthalpy. The study demonstrated that PEF can be utilized to change the starch fraction of cassava flour, which is driven by electric field strength and specific energy input, causing changes in the starch-related properties leading to increased digestibility.

A procedure for determining the number and pattern of digestible starch fractions in multiphasic food digestograms.

Plant-based foods are frequently heterogenous systems, containing multiple starch fractions with distinct digestion rate constants. An unbiased determination of the number and digestion pattern of these fractions is a prerequisite for understanding the digestive characteristics of food. A non-linear least-squares procedure based on a conditional selection of simple first-order kinetics or a combination of parallel and sequential kinetics models was developed. The procedure gave robust results fitting manually generated data, and was applied to in vitro experimental digestion data of retrograded rice starches. By correlating fitting parameters with starch structural parameters, it showed that rice starches with a lower amylose content, longer amylose chains, and amylopectin intermediate chains had more digestible starch fractions after long-term retrogradation. This procedure enables the structural basis of starch digestibility and the development of food products with slow starch digestibility to be better understood. © 2022 Society of Chemical Industry.

Influence of sprouted oat flour substitution on the texture and in vitro starch digestibility of wheat bread.

The aim of this study was to investigate the effect of sprouted oats substitutions on the in vitro digestibility of starch in the wheat bread. The physical and nutritional quality of wheat bread enriched with 20% sprouted oat flour was compared. The polyphenols and γ-aminobutyric acid increased, while the content of starch and β-glucan in the mixed bread was gradually decreased. The specific volume of mixed bread reached the maximum with a 19.79% reduction of area fraction and a 31.36% increase cell density when sprouting for 72h. Two digestible starch fractions with different digestion rates were observed from the LOS-CPS fitted starch digestograms. The microstructure revealed that large type A wheat starch was gelatinized after baking, whereas small type B wheat starch and oat starch were wrapped in protein-β-glucan complexes. This study suggests that properly sprouting has the potential to obtain nutritional bread with low starch digestibility.

Powder structure and gelation behaviour of debranched cassava starches prepared with and without incubation

SummaryThe effect of incubation after debranching on the powder structure and gelation behaviour of debranched cassava starch (DBCS) was investigated. The DBCS samples were prepared by debranching 10% (w/v) cassava starch with pullulanase at 55 °C for 24 h, then incubated at 4 °C for 0, 1, 4, 24 and 72 h and recovered by precipitation with ethanol. The unincubated DBCS appeared as small, sponge‐like aggregates with a rough surface, while the incubated DBCS powders were considerably larger, looked denser and had a smooth surface. The unincubated DBCS had an A + V‐type crystal structure, whereas incubated DBCS samples had a B‐type structure. Crystallinity of all DBCSs was 20–22%. The incubated DBCSs displayed a substantially lower gel setting time compared to the unincubated DBCS, that is, the gel setting time of 10% DBCSs cooked for 10 min reduced from 242 min to 47–52 min when kept at 25 °C. The difference of gel setting time was most likely related to the type of crystal formed as well as the difference in amorphous structure, as indicated by the content of the slowly digestible starch fraction.

Study on Structural and Physicochemical Properties of Modified Corn Starch: Comparison of Ultrasound, Stirring, and Lactic Acid Treatments

AbstractUltra‐sonication has been growingly utilized in starch modification as a green and non‐thermal technology. In this research, the effect of ultrasonic, stirring, and lactic acid treatments alone and with their combination (binary and ternary) on the properties and structure of corn starch is investigated. In the ternary treatment, degree of substitution of lactate on the polymeric chains of the starch is increased, inducing an esterified structure, which imparted to the modified starch a higher swelling power, water holding capacity, water absorption index, oil absorption rate, and amylose content along with lower viscosity and activation energy of gelatinization than native starch and the rest of the treatments. Also, the in vitro starch digestibility test with ternary treatment exhibits lowest rapidly digestible starch fraction, and highest slowly digestible starch and resistant starch fractions. The XRD patterns demonstrate a reduction in crystallinity percentage of the modified starch by the ternary treatment compared to native starch. The images of SEM indicate that ultra‐sonication and acid hydrolysis result in the damage of granules' surface, while sample agitation by stirring causes no change. Esterification of corn starch is proved by FT‐IR. Starch modification by the proposed ternary treatment can be utilized in production of low‐calorie foods.

In Vitro Digestive Analysis of Digestible and Resistant Starch Fractions, with Concurrent Glycemic Index Determination, in Whole Grain Wheat Products Minimally Processed for Reduced Glycaemic Impact

Eight wheat products differing in texture (porridge vs. bread), grain fineness (fine, kibbled, intact), and cooking (raw vs. cooked), with pre-measured glycaemic indexes (GI), were analysed by in vitro amylolytic digestion to determine effects of processing to reduce GI on quantities of starch fractions differing in digestibility. The accuracy and precision of the in vitro analysis was assessed from its ability to concurrently predict clinical GI. In porridges, kernel intactness and lack of cooking reduced GI while increasing Type 1 (inaccessible) and Type 2 (ungelatinised) resistant starch. Porridge in vitro GI values (GIiv), calculated from the area under in vitro digestion curves minus estimated blood glucose disposal, were: raw fine, 26.3; raw kibbled, 12.6; cooked fine, 63.9; cooked kibbled, 44.1; and correlated closely with clinical GI values (R2 = 0.97). In bread, the negative association of kernel intactness and resistant starch with GI was seen in vitro but not in vivo. Bread GIiv values were: roller milled flour, 67.4; stoneground flour 61.1; kibbled grain, 53.0; kibbled + intact kernel, 49.5; but correlation with clinical values was low (R2 = 0.47), and variability in the clinical results was high (clinical CV = 72.5%, in vitro CV = 3.7%). Low glycaemic potency of wheat by minimal processing was achieved by maintaining particle size, avoiding hydrothermal treatment, avoiding crushing and using a food matrix requiring little chewing for ingestion. Use of in vitro digestive analysis for high precision measurement of starch fractions with potential secondary health benefits was validated by accurate concurrent prediction of the glycaemic index but needed to account for effects of chewing.

Addition of amino acids modulates the in vitro digestibility of corn starch

The addition of amino acids (AAs) including glycine (Gly), lysine (Lys) and glutamic acid (Glu) with different concentrations on starch morphological, physicochemical and in vitro digestion properties were studied. While AAs showed no effects on neither morphology nor crystalline characters, they all significantly influenced the starch relative crystallinity and swelling capacity in an order of Glu > Lys > Gly. For all samples, both fastly- and slowly- digestible starch fractions (SF and SS) were observed. While Glu and Gly increased SF content with a faster digestion rate, they reduced SS content with a slower digestion rate. On contrary, Lys reduced SF content and the digestion rate of SS. The inhibitory effects of AAs on starch retrogradation and enzyme activities, the acidic environment and Maillard reaction between starch phosphate monoester and Lys are responsible for altered starch digestibility. This study betters our understanding concerning how AAs interactions affect starch functional properties.

Manipulating the Microstructure of Potatoes for Slow Starch Digestion

ObjectivesPotatoes are nutritious foods that provide essential energy in the form of starch. However, numerous studies have shown that their consumption could lead to high postprandial glycemia. Our aim is to transform staple foods into a healthy diet with modulated postprandial glycaemia and sustained energy.MethodsPotatoes were blanched in a 500 ppm calcium solution for 30 min at 70 °C prior to streaming. We wanted to study if blanching potatoes in the presence of divalent cations increased pectin-cross linking and could lead to a lower cell wall permeability to digestive amylolytic enzymes. Potatoes were submitted to in-vitro simulated gastrointestinal digestion. The digestion of starch occurred in the intestinal phase in the presence of digestive enzymes (1350 U of pancreatic amylase, 3500 U of glucoamylase and 200 U of invertase). Aliquots were obtained at time intervals to quantify glucose release. The diffusivity rate of dextran probes (20 KDa, 60 KDa, and 150 KDa) into isolated potato cells was determined by the fluorescence recovery after photobleaching (FRAP) assay. Texture profile analysis (TPA) was also carried out to quantify multiple textural parameters.ResultsOur treatment increased the slowly digestible starch fraction of potatoes from 10.5% to 35.3%. Treated potatoes had 40.7% and 99.9% lower cell wall diffusivity of 20 KDa dextrans and 70 KDa dextrans, respectively. These results show that a-amylase (∼59 KDa) access to starch within the cells was significantly lower in our treated potatoes. Thus, is the driving factor for the slower starch digestibility rate. These results are unexpected since a-glucosidase is the gatekeeper for starch hydrolysis. Texture analysis showed that treated potatoes possess desirable attributes such as higher hardness which could drive consumer preference.ConclusionsDeveloping slowly digestible staple foods, such as potatoes, is a promising approach for moderating glycemia as well as extending satiation and energy, and, in the long-term, control food intake and bodyweight.Funding SourcesThis research was funded by A*STAR Biomedical Research Council grant IAF-PP (HBMS Domain): Food Structure Engineering for Nutrition and Health.

Addition of 1, 4-α-glucan branching enzyme during the preparation of raw dough reduces the retrogradation and increases the slowly digestible fraction of starch in cooked noodles

Consumers significantly prefer wheat noodles that offer both an acceptable texture and health benefits. To this end, a cold-active 1,4-α-glucan branching enzyme from Bifidobacterium longum (BlBE) was expressed in the generally recognized as safe (GRAS) host cell Bacillus subtilis and then used at 120, 240 or 480 U/g flour in the preparation of raw dough. The storage modulus and loss modulus of the BlBE-modified dough decreased, but the pseudo-plasticity increased. The cooked noodles' hardness, gumminess and chewiness decreased by 12.1%–45.8%, 9.7%–40.4% and 16.0%–42.4%, respectively, but both resilience and cohesiveness increased by 4.0%–14.8% and 1.8%–9.0%, respectively. Pearson analysis revealed a correlation between the noodles' textural parameters and the doughs' power law equation parameters. BlBE-modified noodles exhibited significantly (P < 0.05) lower differential scanning calorimetry retrogradation enthalpies during storage at 4 °C for 7 days and released significantly lower levels of glucose during incubation with mammalian α-glucosidase at 37 °C for 10 min–360 min. BlBE at 480 U/g flour increased the slowly digestible portion by 12.6%. BlBE decreased the molecular weight, x-ray diffraction crystallinity, and fourier transform infrared spectroscopy ratio of band's heights at 1045 cm−1 and 1022 cm−1 of starch but increased the amylopectin content and ratio of short- to long-branch chains. These structural changes in starch partially explained the reduced retrogradation and enhanced slowly digestible starch fraction in the noodles.

Effects of psyllium fiber on in vitro digestion and structure of different types of starches.

Starch digestibility in foods strongly depends on the structure, other ingredients and processing conditions used. This study aimed to investigate the effect of psyllium fiber on gelatinization, crystallinity and in vitro digestibility of starches having different crystalline structures (A, B and C). Wheat, potato and tapioca starches with and without added psyllium fiber were heated at 90 °C for 10min at three different solid:water (w:v) ratios (1:1, 1:2 and 1:5). The added fiber content was 50% (dry base) in the solid fraction for the fiber-added samples. Wheat, potato and tapioca starches showed different structural, morphological and starch digestibility properties. The effect of cooking and fiber addition on starch digestion differed for the starch types, mainly wheat starch. Psyllium addition during cooking decreased the rapidly digestible starch (RDS) fractions while increasing the slowly digestible starch (SDS) and remaining/resistant starch (RS) fractions. The effect of psyllium fiber addition was not limited to restricting the swelling and gelatinization of starch granules during heating. Psyllium fiber effectively restricted the mobility of digestive enzymes during digestion. Understanding the relationship between psyllium and starch digestibility for different types of starch could assist in designing food formulations with lower starch digestibility. These in vitro data, however, should be confirmed by in vivo studies. © 2021 Society of Chemical Industry.

Effects of psyllium and cellulose fibres on thermal, structural, and in vitro digestion behaviour of wheat starch

SummaryThe study investigated the effects of adding different types of fibre (psyllium and cellulose) on in vitro digestion behaviour of wheat starch with its thermal and structural properties. Psyllium and cellulose fibres interfered with the wheat starch differently. Psyllium fibre hindered starch gelatinisation, restricted the loss of starch crystallinity, and decreased the accessibility of enzymes to starch. In contrast, cellulose fibre had no significant effect on gelatinisation and loss of crystallinity but limited the digestive enzyme mobility. The impact of psyllium was more pronounced than cellulose on reducing starch digestibility. Rapidly digestible starch fractions of the cooked starch reduced from between 57.90 ± 0.60–69.72 ± 0.46 (% in starch) to between 28.06 ± 0.36–46.34 ± 1.10 (% in starch) and 53.23 ± 0.36–66.71 ± 0.24 (% in starch) for psyllium and cellulose fibre, respectively. This information could be helpful to design foods containing starch with reduced digestibility for a healthy diet.