Biological factors controlling starch digestibility in human digestive system

Starch digestion rate and location in the gastrointestinal tract(GIT)are critical for human health.This review aims to present a comprehensive summary on our current understanding of physiological,biochemical,anatomical and geometrical factors of human digestive system that are related to in vivo starch digestibility.It is shown that all digestive compartments including mouth,stomach,small intestine,and large intestine play critical roles in regulating the overall starch digestion process.A proper investigation of starch digestion pattern should thus be based on the consideration of all these compartments.Main biological factors are summarized as oral mastication and salivation,gastric emptying and motility,small intestinal enzymes and motility,large intestinal resistant starch(RS)-microbiota interactions and gut-brain feedback control,as well as glucose adsorption and hormonal feedback control.However,connections among these biological factors in determining starch digestive behaviors remain elusive.This is due to the inherent complexity of human GIT anatomy,motility and biochemical conditions,as well as ethical,financial and technical issues in conducting clinical studies.Much technological and scientific efforts from both clinical studies and in vitro simulation models are required for a better understanding of in vivo starch digestion behaviors.

Methodological impact of starch determination on starch content and ileal digestibility of starch in grain legumes for growing pigs

Background： Grain legumes represent a valuable energy source in pig diets due to their high starch content. The present study was conducted to determine the content and apparent ileal digestibility（AID） of starch in different grain legume cultivars for pigs by means of both a polarimetric and enzymatic method for starch determination.Methods： Three experiments were conducted with six barrows each which were fitted with ileal T-cannulas. In total, 18 diets including six different cultivars of faba beans（Vicia faba L.） and peas（Pisum sativum L.）, five different cultivars of lupins（Lupinus luteus L., Lupinus angustifolius L.）, and one diet with a soybean meal（SBM） were fed.Results： The starch content of faba beans and peas was greater（P ＆lt; 0.05） when determined polarimetrically than enzymatically（438 vs. 345 g/kg dry matter（DM） in faba beans and 509 vs. 390 g/kg DM in peas, respectively）.Considerable lower starch contents were obtained in lupins and SBM, with 82 and 48 g/kg DM（analyzed polarimetrically） and ＆lt;1.1 and 3 g/kg DM（analyzed enzymatically）, respectively. Mean values for contents of neutral detergent fiber（NDF） and acid detergent fiber（ADF） in grain legumes ranged from 111 and 79 g/kg DM in peas to248 and 207 g/kg DM in lupins, respectively. Contents of condensed tannins in the colored flowered faba bean cultivars ranged from 2.1 to 7.4 g/kg DM. The AID of starch was greater（P ＆lt; 0.05） in pea than in faba bean cultivars,and using the polarimetric starch determination method resulted in greater（P ＆lt; 0.05） digestibility values than using enzymatic starch analysis（84 vs. 80% in faba beans and 86 vs. 83% in peas）. Moreover, AID of starch differed（P ＆lt; 0.05）within pea cultivars and starch digestibility in faba beans decreased linearly（P ＆lt; 0.05） as the content of condensed tannins increased. However, there was no relationship between contents of NDF and ADF and AID of starch in pea and faba bean cultivars.Conclusion： Both contents and AID of starch in grain legumes can vary as influenced by the analytical method used for starch determination. Generally, starch digestibility is greater when measured by polarimetric rather than enzymatic methods.

Influence of replacement of wheat flour by rice flour on rheo-structural changes, in vitro starch digestibility and consumer acceptability of low-gluten pretzels

This study aimed to access the influence of rice flour incorporation on various quality attributes of low-gluten wheat-based pretzels viz., functional, rheological, starch digestibility, color, textural and sensorial properties. Significant increase in swelling power (18.33 ± 0.51) and bulk density (0.58 ± 0.04) was observed in flour blend upon incorporation of rice flour, whereas, significant decrease in oil absorption capacity (0.62 ± 0.09), solubility index (6.72 ± 0.17), foaming capacity (9.67 ± 0.34), and foaming stability (3.39 ± 0.15) was recorded. Pasting properties of samples were studied using a Rapid Visco Analyser which indicated that all the pasting properties increased with an increase in rice flour incorporation. Fourier transform infrared spectroscopic studies revealed no difference in the basic functional groups of flour blend upon the incorporation of rice flour, however, it had a pronounced effect on elastic modulus (G′) of flour blend. In vitro starch digestion characteristics revealed 7.23% surge in slowly digestible starch and 13.36% reduction in rapidly digestible starch of developed low-gluten pretzels upon the incorporation of rice flour. Apparent amylose content (27.3 ± 1.45) and resistant starch content (6.12 ± 0.97) increased and starch digestibility index (69.87 ± 1.72) decreased in developed low-gluten pretzels. In conclusion, the developed low-gluten pretzels had significantly (p < 0.05) higher mineral profile and lightness (L*) and lower breaking strength in addition to having better overall acceptability. This study indicated that substituting wheat flour with rice flour up to a level of 35% affected the quality attributes of developed low-gluten pretzels.

Effects of Chinese chestnut powder on starch digestion,texture properties,and staling characteristics of bread

Chestnut is a high nutritional value food that has been widely used as a tonic in traditional Chinese medicine.As an emerging functional food ingredient,Chinese chestnuts are rich in a range of bioactive nutrients such as starch,dietary fiber,fat,protein,trace metal element and vitamins A,B,C,D and other nutrients.In our study,Chinese chestnut powder(CCP)were added into bread formulation at 2%-6%levels(based on flour weight)to produce fresh bread with enhanced anti-staling characteristics and starch digestion inhibitory ability.The texture properties,retrogradation enthalpy,water distribution,and estimated glycemic index(eGI)of wheat bread containing CCP as a functional additive were also investigated.The results showed that incorporation of CCP apparently affected bread texture,resulting in increased hardness,as well as decreased the specific volume of wheat bread.These influences were generally proportional to the amount of CCP used.It was found that adding too much CCP resulted in a dark red color,showing increased significantly higher total color difference(ΔE)and L values.Conversely,addition of CCP significantly reduced starch digestion rate and digestion extent in bread,and the reduction degree was positively related to the amount of CCP applied.The greatest reduction in eGI value from 79.40(control)to 75.02(6%CPP bread)was observed.Meanwhile,the content of resistant starch of 6%CPP bread was about 1.36 times higher than that of control bread.CCP also reduced crumb water loss and drove the water shift from the bound to the mobile state after stored for 7 days.The retrogradation enthalpy analyses further confirmed that CCP inhibited starch retrogradation and recrystallization.These results suggested that Chinese chestnut powder could be incorporated into fresh bread to provide health functions,such as lowering potential glycaemic response and improving anti-staling characteristics of bread.

Insights into the relations between cell wall integrity and in vitro digestion properties of granular starches in pulse cotyledon cells after dry heat treatment

Natural foods,such as whole pulses,are recommended in the dietary guidelines of the US and China.The plant cell wall structure in whole pulses has important implications for the nutritional functionalities of starch.In this study,garbanzo bean cells with varying degrees of cell wall integrity were subjected to dry heat treatment(DHT)and used to elucidate the food structure-starch digestion properties of pulse food.The morphological features suggested that all cell samples do not exhibit remarkable changes after being subjected to DHT.Molecular rearrangement and the crystallite disruption of starch granules entrapped in cells occurred during DHT as assessed by the crystal structure and thermal properties.DHT decreased the inhibitory effects of enzymes of both the soluble and insoluble components,but the digestion rate and extent of slightly and highly damaged cell samples did not exhibit significant differences compared with their native counterparts.We concluded that the starch digestion of pulse cotyledon cells is primarily determined by the intactness of the cellular structure.This study reveals the role of food structure on the ability to retain the desirable nutritional properties of starch after subjection to physical modification.

Inhibitory effect and mechanism of tannic acid against two starch digestive enzymes

Backgrounds:Tannic acid(TA),as a plant-derived phenolic substance,is involved in regulating the activity of starch digestive enzymes,but its underlying mechanism remains unclear.Methods and Results:In the present study,inhibition rate and inhibition kinetics assays were performed and confrmed that TA had a strong inhibitory effect on bothα-amylase andα-glucosidase with IC50 values of 0.1585 mg/mL and 0.00542 mg/mL,respectively,through a mixed inhibition mode.The secondary structures of both enzymes were confrmed to be modifed by TA through circular dichroism(CD)spectra.Fluorescence quenching analysis revealed that the interaction between TA and two enzymes was a static process of pontaneous complex formation.Finally,molecular docking revealed that non-covalent bonds were the main interaction forces between TA and both enzymes.Conclusions:Thus,TA was a promising candidate for the inhibition of starch-digesting enzymes,and the present research provided insight into postprandial glucose regulation through polyphenols.

The Effect of Potato Varieties and Processing Methods on Glycemic Response

In order to identify those potatoes which exert a low glycemic impact after processing, eight early potato varieties and four processing methods were evaluated for their total starch content, amylose content, rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS), estimated glycemic index (eGI), glycemic load (eGL) as well as their relationship among each other. While all these profiles were highly dependent on the potato variety and processing methods, all the eight varieties were classified as low GL foods (p ≤ 0.05). A strong positive correlation was observed between eGI and RDS (r = 0.84, 0.79, and 0.74) for retrograded and reheated, baked and microwaved varieties, respectively), whereas a moderate negative correlation was observed between eGI and RS for retrograded and reheated (r = -0.39) and microwaved (-0.37) varieties (p ≤ 0.05). On the basis of these findings, it can be concluded that potato variety, processing methods, and starch characteristics define the eGI and eGL. Furthermore, for the varieties examined, the present study identified RDS as a major starch factor contributing to eGI.

The granule characteristics of yam,sweet potato and tapioca starches determined by gravitational field-flow fractionation

To study the characteristics of tuber starchgranules,firstly,three kinds of common tuber starches were separated and characterized by gravitational field-flow fractionation(GrFFF)instrument,and the ratios of large and small starch granules A/B were calculated.Then,the liquid of peak A and peak B was collected and observed by scanning electron microscope(SEM)to verify the separation result of GrFFF.Secondly,the particle size distribution and crystal characteristics were characterized by particle size analyser,X-ray diffraction(X-ray)and fourier transform infrared spectroscopy(FT-IR).Three kinds of tuber starches all had the bimodal distribution in GrFFF.Peak A contained large particles,and peak B contained small particles.For yam starch,the ratio of starch granules A/B was much higher than 1;for sweet potato starch the ratio was approximately equal to 1;for tapioca starch,the ratio was much lower than 1.Moreover,the starch granules of sweet potato and tapioca were both A-type crystallinity,while yam starch granules were C-type crystallinity.GrFFF could be used to characterize and separate large and small granules of tuber starches and estimate the ratio of starch granules A/B.Yam starch was suitable for the development of slowly digestible starch(one kind of functional food),which could delay the occurrence of metabolic syndrome,diabetes and cardiovascular diseases.Tapioca starch was suitable for plant capsules,which were safer than gelatin capsule and could prevent the"poison capsule"incident from happening.

Succinylation improves the slowly digestible starch fraction of cardaba banana starch. A process parameter optimization study

The study investigated the improvement of slowly digestible starch fraction of cardaba banana via octenyl succinic anhydride(OSA)modification process.A nonlinear(Response surface methodology[RSM]and artificial neural network[ANN])and linear(partial least square[PLS])modelswere employed and their predictabilitywas compared.The result revealed that all the modelling techniques were accurate in predicting the experimental process.The optimized RSM values for the production of slowly digestible starch(SDS)fraction were OSA concentration of 4%,reaction time of 47.49 min,and pH of 10 with a predicted SDS value of 44.64%.Among the modelling techniques,ANNwas adjudged as the predictivemodel for improving the SDS yield.The regression coefficient coupled with the variable important in the projection(VIP)values of the PLS model indicated that the OSA concentrationwas themost important factors responsible for high SDS yield.Finally,a structural comparison of the optimized starch against native starch revealed the formation of high ordered crystalline structure of the starch due to the impregnation of the modifying agent to the hydroxyl group of the cardaba banana starch.

Modulating of food glycemic response by lactic acid bacteria

There are some strategies for modulating the glycemic response of food through synthesized metabolites such as organic acids,fatty acids,sugar alcohols,bioactive peptides,and exopolysaccharides by bacteria,yeast,and/or fungi during fermentation.The different species of lactic acid bacteria (LAB) are the most important option in fermented food production because they are considered food-grade,their products can be directly used in food,their usability of a cheap and wide range of substrate,and suitable for genetic modification.They can contribute to lowering the glycemic load of nutrition through their organic acid,alcohol,polysaccharides,and vitamin production.This study aimed to review the effects of lowering the glycemic responses of foods by LAB via metabolites produced and their contribution to human well-being in this way.

Net energy,energy utilization,and nitrogen and energy balance affected by dietary pea supplementation in broilers

Pea starch consists predominantly of C-type of amylopectin chain which is more resistant to digestive enzymes than A-type of starch thus slowly digested in poultry.It was hypothesized that the presence of slowly digested pea starch in broiler diets will increase net energy and the efficiency of energy utilization in broilers.Two experiments were performed to investigate starch digestibility of pea at different in-cubation times(in vitro study)and the effect of dietary pea on heat increment and net energy in broilers using an open-circuit respiratory calorimetry system(in vivo study).One-day-old Ross 308 male broilers were fed a common starter crumble from d 1 to 10 and standard grower diets thereafter.At d 21,birds were transferred to the chambers each housing 2 birds.Each treatment was replicated 6 times with 2 identical runs of 3 replicates per treatment.A wheat-soybean meal-based diet was used as a control and the treatment diet contained 500 g of pea/kg pea.In vitro study showed that pellet processing increased(P<0.001)starch digestibility,particularly at shorter times for wheat and a much larger response for pea.Birds offered the pea-based diet had lower(P=0.002)feed intake,lower(P=0.020)body weight gain,but a similar(P>0.05)FCR compared to those offered the wheat-based diet.Net energy(NE)and apparent metabolizable energy(AME)values were higher in the pea-based diet than in the wheat-based diet(P-0.037 for NE and P-0.018 for AME).Heat production,respiratory quotient,heat increment of feed,efficiency of utilization of gross energy for AME,and efficiency of utilization of AME for NE did not differ(P>0.05)between the 2 treatments.There was no effect(P>0.05)of pea on the total tract di-gestibilities of dry matter,crude protein and ash,but the total tract digestibility of starch was higher(P-0.022)in the pea-based diet compared to the wheat-based diet.This study provides insight into the energy metabolism of broilers offered a pea-based diet and indicates that dietary pea supplementation increases dietary AME and NE but has no effect on heat increment of feed and the efficiency of energy utilization in broilers.