High-amylose Maize Starch Research Articles

In vitro colonic fermentation profiles and microbial responses of propionylated high-amylose maize starch by individual Bacteroides-dominated enterotype inocula

The concept of “enterotype” has been proposed to differentiate the gut microbiota between individual humans, and different dominant bacteria utilize fiber substrates with different fermentation properties and microbial changes. In this study, we made propionylated high-amylose maize starch and investigated both in vitro fecal fermentation properties and microbial responses by individual Bacteroides-dominated enterotype inocula. Propionyl group substitution of HAMS did not significantly change gas production profiles, suggesting that the gas production during fermentation is independent of propionylation. The final concentration of released propionate significantly increased (10.26–12.60 mM) as a function of propionylation degree, suggesting that the introduced propionyl groups can increase the concentration of short-chain fatty acids (SCFA) during colonic fermentation. At the genus level, Bacteroides was obviously promoted for all donors with the final abundance in the range of 0.1–0.24, indicating that propionylated high-amylose maize starch changed the structure and abundance of microbiota compared to unmodified starch. Besides, the non-metric dimensional scoring (NMDS) plots showed that those changes were related to the initial microbiota composition. The results may offer useful information for the design of personalized food products and relevant therapies at least within Bacteroides-dominated enterotype.

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.

Preparation and characterization of chemically modified high amylose maize starch-ascorbyl palmitate inclusion complexes in mild reaction condition

Acetylation (0.48, 1.03, and 2.06%) and oxidation (0.48, 0.97, and 1.91%) of high amylose maize starch (HS) were used to encapsulate ascorbyl palmitate (AP). The V-amylose inclusion complexes could be prepared without pre-autoclaving HS. AP could be effectively encapsulated into modified HS (3.43–6.86%), and the modified complexes exhibited increased solubility and stability in an aqueous environment than the unmodified complex. AP in modified complexes exhibited similar stability against light and oxidation with the unmodified complex. Both modifications decreased the crystalline area, peak melting temperature, and enthalpy. Accordingly, the stability of AP in modified complexes against heat treatment was reduced. This study could expand the useable range of high amylose starch inclusion complex with AP and other ligands, especially in an aqueous environment.

Structural disorganization of cereal, tuber and bean starches in aqueous ionic liquid at room temperature: Role of starch granule surface structure

The structural disorganization of different starches in a 1-ethyl-3-methylimidazolium acetate ([Emim][OAc])/water mixture (1:6 mol./mol.) at room temperature (25 °C) was studied. For normal cereal starches, which have pinholes randomly dispersed on the granule surface or only in the outermost annular region (wheat starch), the aqueous ionic liquid (IL) completely destroyed the granule structure within 1–1.5 h. Pea starch (PeS) granules with cracks were destroyed by the aqueous IL within 6 h. High-amylose maize starch (HAMS), as well as potato and purple yam starches (PoS and PYS), which have a dense and thick outer granule layer, were even more resistant to the action of the solvent. Structural disorganization was accompanied by increased viscosity and controlled the binding of water molecules with starch chains. From this study, we concluded that the surface characteristics of starch granule are an important factor affecting starch structural disorganization in an aqueous IL.

Effect of type-2 resistant starch (high-amylose maize starch) on the physicochemical, nutritional, in vitro starch digestibility and estimated glycaemic properties of Chinese steamed buns

Resistant starch (RS) is a portion of starch that resists enzymatic digestion. It is applied in the production of Chinese steamed bun (CSB) to increase daily fibre intake. In this study, the incorporation of type-2 RS known as high-amylose maize starch (HM) (5%, 10%, 15%, 20%, 25% and 30%) and its effect on the rheological and physicochemical properties, nutritional values, in vitro starch digestibility and estimated glycaemic index (eGI) properties of CSBs were determined. High HM incorporation levels increased RS and dietary fibre contents and reduced the pasting viscosities and calorific values of CSBs. The addition of HM-enriched RS also affected total starch content and eventually resulted in the decreased susceptibility of starch to digestive enzymes in vitro. The decrement in starch hydrolysis rate markedly reduced the eGI of HM-containing CSBs. The incorporation of 25% HM into CSBs (eGI = 68.45) could be applicable in developing a nutritious and medium-eGI CSB without jeopardising desirable physical attributes.

Microbiota fermentation characteristics of acylated starches and the regulation mechanism of short-chain fatty acids on hepatic steatosis.

Starches acylated with specific short-chain fatty acids (SCFAs) have the potential to provide specificity in SCFA delivery. It is well documented that SCFAs are involved in lipid metabolism, but the underlying mechanism is still unclear. For characterizing the fermentation properties of acylated starches with various SCFAs in terms of SCFA production, three different acylated starches were prepared following the esterification of high amylose maize starch (HAMS) using acetic anhydride, propionic anhydride and butyric anhydride, respectively. Compared with HAMS, the gut microbiota fermentation of acetylated, propionylated and butylated starches specifically increased the production of acetic acid, propionic acid, and butyric acid, respectively, indicating that the introduced acyl group can be effectively released during the fermentation process. Furthermore, the utilization of these starches generated more total SCFAs, suggesting that they can be effectively fermented by the microbiota as a carbohydrate substrate. Study on an in vitro model of cultured rat hepatocytes indicated that either mixed SCFAs or butyrate play an important role in regulating lipid metabolism via activating AMPK and PPAR signaling pathways, implying the importance of butyrate in the improvement of lipid metabolism and accumulation. This study may provide further understanding of the individual function of the corresponding SCFA.

Effects of Type-2 Resistant Starch (High-Amylose Maize Starch) on the Glycemic Index of Chinese Steamed Buns and Its Influence on Glycemic Response in Healthy Human Subjects

The incorporation of resistant starch (RS) in food has gained importance to be a good replacement for carbohydrate. This study aimed to determine the effects of resistant starch (RS) known as high-amylose maize starch (HM) as wheat flour substitute in Chinese steamed bun (CSB) formulation on postprandial glycemic response in healthy human subjects. In the single-blind cross-over experimental trial, subjects (female, n=15) consuming 30% HM (HM30) composite CSB had significantly lower postprandial blood glucose response compared with control consuming CSB (without HM) within 2 hours after ingestion of both samples. Compared with control CSB, HM30 produced lower glycemic response with a mean iAUC of 105.2 mmol x min/L. The mean iAUC of control CSB was 186.1 mmol x min/L. The low GI property of HM30 stabilized the blood glucose concentration level and did not cause sudden rapid increase in blood glucose concentration similar to high-GI reference food and medium-GI control CSB. Funding Information: This study was supported through funding from the Ministry of Higher Education Malaysia (MoHE), project code: FRGS/1/2017/STG/UMS/02/5. Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: The study was ethically approved by the Medical Research Ethics Committee of Universiti Malaysia Sabah [Refer to Appendix D; UMS/FPSK6.9/100-6/1/95; JKEtika 3/18(7)]. The informed consent form was signed by the subjects to ensure their voluntary enrolment to participate in the study.

Novel porous starch/alginate hydrogels for controlled insulin release with dual response to pH and amylase.

An important principle in the development of oral insulin is to protect insulin from the harsh conditions of the stomach and release it in a controlled manner in the intestine. In the present study, novel insulin-loaded porous starch-alginate hydrogel systems (In-S-Alg) including In-MS-Alg (prepared with porous maize starch), In-WS-Alg (porous waxy maize starch), and In-RS-Alg (porous rice starch) were successfully developed. As a representative, In-MS-Alg was further coated with gelatinized-retrograded high amylose maize starch (HA) films with different thicknesses to prepare In-MS-HA/Alg hydrogel beads for improving the functionality of controlled release of insulin under the action of α-amylase. The In-S-Alg and In-MS-HA/Alg hydrogel beads were evaluated in terms of structural and morphological properties, encapsulation effect on insulin as well as its release behavior. The results show that insulin was distributed in the pores and cavities of porous starch granules. In In-MS-HA/Alg hydrogel beads, insulin was increasingly blocked inside porous starch with the increased thickness of the HA film. Encapsulation efficiency of insulin in all In-S-Alg and In-MS-HA/Alg hydrogel beads was >80%. Amazingly, both the hydrogel beads successfully achieved the goal of triggered release upon pH changes and α-amylase addition. Most of the insulin (about 90%) was retained in the simulated gastric fluid; while the release rate of insulin in the simulated intestinal fluid increased gradually, and was further accelerated in the presence of α-amylase. Furthermore, for the In-MS-HA/Alg hydrogel beads, the insulin release rate can be gradually reduced by increasing the thickness of the HA film, which provided the possibility to match the rate of increase of the blood glucose level after the intake of food with different glycemic indices. Therefore, the novel hydrogel prepared in this study may be a promising and safe delivery carrier for oral insulin.

Gelation characteristics of Mesona chinensis polysaccharide-maize starches gels: Influences of KCl and NaCl

An investigation was conducted into the effects of potassium chloride (KCl) and sodium chloride (NaCl) on the gelation properties of maize starch-Mesona chinensis polysaccharide (MCP) gels. Waxy maize starch (WS), normal maize starch (NS), and high amylose maize starch (HS) were used to compare the effects of different amylose contents on the gel properties of maize starch-MCP gels. The results showed that KCl and NaCl have similar effects on the gelation, rheological, and structural properties of maize starch-MCP gels. The addition of KCl and NaCl increased the pasting viscosity, breakdown values, setback values, dynamic modulus, and apparent viscosity of maize starch-MCP gels, especially for HS-MCP gels. LF-NMR (Low-field nuclear magnetic resonance) showed that salts reduced bound water content while increasing the free water content of maize starch-MCP gels. CLSM (Confocal laser scanning microscopy) results also indicated that salt can restrict the expansion and maintain the integrity of starch granules, especially for WS-MCP gels.

Inhibitory effect of four types of tea on the in vitro digestion of starch

AbstractPhenolic compounds have been shown to decrease the rate of starch hydrolysis by inhibiting digestive enzymes for starch. Tea, rich in phenolic compounds, has been widely reported for its beneficial health effects. This study explored the inhibitory abilities of four types of tea, that is, green tea (GT), oolong tea (OT), black tea (BT), and white tea (WT), on the in vitro enzymatic digestion of potato starch (PS) and high‐amylose maize starch (HAMS), using two in vitro digestion methods. All teas significantly inhibited the digestion of both starches, with a few exceptions at some time points. The resistant starch content was increased by all four teas in HAMS, but only by BT and WT in PS. The total phenolic contents in the teas could not predict the inhibitory ability of the teas, possibly due to the structural diversity of phenolic compounds and the presence of other compounds that could also alter enzymatic activity. Our results suggested that tea, regardless of its type, can slow down the enzymatic digestion of starch and therefore imply a potential benefit for controlling postprandial hyperglycemia.

Effect of amylolysis on the formation, the molecular, crystalline and thermal characteristics and the digestibility of retrograded starches

This study evaluated the effect of amylases on the formation, and characteristics of retrograded starches using sweet potato (SPS), cassava (CAS) and high amylose maize (HAS) starches. The starches were gelatinized, hydrolyzed with fungal or maltogenic α-amylase, de-branched and retrograded. The modified starches were then analyzed for digestibility, chain size distribution, relative crystallinity and crystallite size, thermal properties and the proportion of double helices. CAS was the most susceptible and HAS the most resistant to the action of both enzymes. Amylolysis was efficient in forming resistant starch type 3 (RS3) and high levels (> 60%) were found for all starches. RS3 content was highly correlated with the proportion of chains with degrees of polymerization between 13 and 30 for all starches, especially for the root starches, while for HAS, the high amylose content and reduction in the size of amylose chains and very long amylopectin chains also deeply contributed for the RS3 formation. These sizes (DP 13–30) are best suited for the formation of a more crystalline, more perfect, and more strongly bonded structure, composed of larger crystallites, and with a higher concentration of double helices. High correlation coefficients were found between RS3, relative crystallinity, crystallites size, and enthalpy change.

Amylose content modulates maize starch hydrolysis, rheology, and microstructure during simulated gastrointestinal digestion

In this study, the microstructure, rheology, and starch hydrolysis of cooked normal (NAM) and high (HAM) amylose maize starch solutions with various dry matter contents (10, 30 and 50 wt %) were compared before and during simulated gastrointestinal digestion. Prior to digestion, increased rheology (modulus and shear viscosity) and more compact gel network structure were observed for both the NAM and HAM with increasing dry matter content. As compared to the NAM, the HAM with the same dry matter content (50 wt%) showed higher rheology and denser gel structure with remarkable aggregation of relatively intact starch granules after cooking. The extent of starch hydrolysis was similar (~10%) between the two starch systems at the gastric digestion phase, whereas it was significantly lower for the HAM in relation to that for the NAM at the intestinal digestion phase. At the end of the GIT digestion, the in vitro digestibility was about 81% and 90% for the HAM and NAM, respectively. The starch hydrolysis was strongly supported by the rheology and microstructure of the starch digesta. Due to the dilution of digestive fluids and starch hydrolysis, the rheology was both remarkably decreased, but the HAM showed significantly higher shear viscosity than the NAM at each digestion phase due to its greater retention of relatively intact starch granules that would cause higher resistance toward shearing. The results indicate that the amylose content was crucial for modulating starch hydrolysis by forming denser gel structure and increasing digesta rheology that would retard the access of digestive enzymes to the starch granules during digestion.

Comparison of the structure and properties of hydroxypropylated acid-hydrolysed maize starches with different amylose/amylopectin contents

Dually modified regular maize starch (RMS) and high-amylose maize starch (HAMS) were successfully prepared by first acid hydrolysis and subsequently hydroxypropylation. The effects of hydrolysis time (0–24 h) and propylene oxide (PO) content (10–30%) on the structure and physicochemical properties were investigated. The molar substitution (MS) of HAMS samples (up to 0.163) was generally higher than that of RMS samples (up to 0.149), suggesting the higher reactivity of amylose for hydroxypropylation. Besides, PO content had a greater influence on MS whereas the effect of acid hydrolysis time was minor. For both starches, the dual modifications did not cause apparent changes to the granule morphology but reduced gelatinisation temperatures and enthalpy; and a higher PO content led to higher relative crystallinity. These results suggest that hydroxypropylation occurred mainly on the surface of HAMS granules and had little influence on the compact granular structure, whereas this reaction impacted the internal structure of RMS much more. The rheological study shows the introduced hydroxypropyl bulky groups weakened the entanglements between amylose chains or amylopectin chains with long branches. Thus, this work provides insights into the rational design of modified starch products containing different amylose/amylopectin contents with tailored properties.

Insights into the effects of caffeic acid and amylose on in vitro digestibility of maize starch-caffeic acid complex

Starch digestibility can be decreased by phenolic acids. The physicochemical and digestive properties of high-amylose maize starch, normal maize starch (NMS) and waxy maize starch (WMS) complexed with caffeic acid (CA) were investigated to determine the effects of CA and amylose on starch digestibility. CA inhibited the activity of α-glucosidase and α-amylase in a dose-dependent manner. The inhibitory effect of CA on α-glucosidase was reversible and anti-competitive, while that on α-amylase was irreversible. With the increase of the amylose content in starches, the complexing index of starch-CA decreased, while the relative crystallinity increased. The crystallinity of all three starches decreased after incorporating CA, and the hydroxyl peak in the 1H-NMR spectrum of the WMS-CA complex increased significantly. The resistant starch content of the WMS-CA and NMS-CA complexes increased significantly compared with the control. The inhibitory effect of CA on amylolytic enzymes played a major role and the change of starch structure exhibited a minor role in the digestibility of the maize starch-CA complexes.

The relationship between the expression pattern of starch biosynthesis enzymes and molecular structure of high amylose maize starch

Two high amylose (HAM) inbred lines with apparent amylose contents of 55 % and 62 %, respectively, were selected to explore the relationship between molecular structure and gene expression of starch-synthase involved enzymes. GPC analysis of debranched starches showed that the HAM starches (HAMSs) had shorter amylose chains and longer amylopectin chains than normal maize starch (NMS). FACE analysis showed that these HAMSs had a higher content of amylopectin chains of DP > 21. Quantitative Real-Time PCR analysis showed that the HAM lines had specifically low expression of the starch branching enzyme IIb (SBEIIb), and the starch synthase IIIa (SSIIIa) homologue, and high expression of the isoamylase 2 (ISA2), potentially suppressing the generation of amylopectin molecules through deficient branching and excessive debranching process, thereby increasing the relative amylose content. A high expression of GBSS1 was potentially associated with increased short amylose chain lengths in HAMSs.

4033 Evaluating the Effect of Prebiotics on the Gut Microbiome Profile and Beta-cell Function in Newly-Diagnosed Type 1 Diabetes

OBJECTIVES/GOALS: Type 1 diabetes (T1D) results from the autoimmune destruction of insulin-producing β-cells. Emerging data suggest that differences in intestinal microbiota might be critically involved both in autoimmunity and in glucose homeostasis. The prebiotic high amylose maize starch (HAMS) alters the gut microbiome profile and metabolites positively by increasing production of beneficial short chain fatty acids (SCFAs) that have significant anti-inflammatory effects. HAMS also improves glycemia, insulin sensitivity and secretion in healthy non-diabetic adults. Further, an acetylated and butyrylated form of HAMS (HAMS-AB) that increases beneficial SCFA production, namely acetate and butyrate, has been safe and effective in disease prevention in mouse T1D models. The objective of the proposed study is to assess the effect of administering a prebiotic, such as HAMS-AB, on the gut microbiome profile, SCFA production, glycemia and β-cell function in humans with T1D. METHODS/STUDY POPULATION: We hypothesize that administration of HAMS-AB will (i) improve the gut microbiome profile in humans with T1D, (ii) increase SCFA production, and (iii) improve β-cell health, β-cell function and overall glycemia. We propose a pilot randomized controlled cross-over trial of HAMS-AB in 12 youth with newly-diagnosed T1D. We will use state-of-the-art markers to profile the gut microbiome (using 16S rRNA sequencing), measure stool SCFA levels (using gas chromatography), asses β-cell stress/death (by measuring proinsulin to C-peptide ratios) and glycemia (assessed by continuous glucose monitoring and HbA1c measurements). RESULTS/ANTICIPATED RESULTS: We expect that the use of HAMS-AB in newly diagnosed youth with type 1 diabetes will alter the gut microbiome profile (thus increasing the number of fermenters and SCFA levels), β-cell function and glycemia in humans with T1D. DISCUSSION/SIGNIFICANCE OF IMPACT: Given the unknown long-term effects of immune-modulatory therapy on those at risk for or those diagnosed with T1D, the use of a prebiotic such as HAMS-AB offers a simple, safe, yet inexpensive and tolerated dietary alternative approach to mitigating disease.

Inhibition of Starch Digestion by Dallic Acid and Alkyl Gallates

Abstract Objectives Retardation of starch digestion is an effective way of optimizing glycemic response. Certain bioactive food components inhibit starch digestion by binding with starch digestive enzymes or starch molecules in the digestive tract. Inclusion complexation between starch and guest compounds is a specific non-covalent binding mode and may contribute to a lower digestibility of starch. The aim of this study was to examine the inhibitory effects of alkyl gallates on in vitro starch digestion and the mechanism of inhibition. Methods Raw and cooked high amylose maize starch (HAMS) and potato starch (PS) were tested for in vitro enzymatic digestion. Gallic acid (GA) and alkyl gallates, including butyl (BG), octyl (OG), dodecyl (DG), hexadecyl (HG), and octadecyl (SG) gallates, were either added during digestion or processed to form inclusion complexes with starch prior to digestion. Starch digestibility profiles, represented by rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) contents, were determined. Results GA and alkyl gallates significantly increased (P &amp;lt; 0.05) RS content in raw starches. Cooked starches had significantly lower RS contents than raw starches. GA and BG increased RS content in cooked HAMS, while all compounds except for SG increased RS content in cooked PS. DG and HG caused a significant increase in SDS contents in cooked HAMS but not in raw starches and cooked PS. Significant increases in SDS and RS contents were seen in HAMS inclusion complexes with DG and HG, compared with uncomplexed starch. Conclusions The bioactive food components tested could all inhibit starch digestion either by inhibiting the enzymes or by forming starch inclusion complex. As alkyl chain length increased, their inhibition on enzymatic activity decreased, but their ability to bind starch increased. While cooking makes starch more digestible, adding certain bioactive food components could compensate for RS loss, suggesting a practical way of modulating glycemic response. Funding Sources USDA National Institute for Food and Agriculture.

Amylose content and specific fine structures affect lamellar structure and digestibility of maize starches

The molecular and lamellar structures and in vitro digestibility of high amylose maize starch granules were investigated. Size-exclusion chromatography (SEC) analysis of hydrodynamic radius (Rh) and relative contents (RC) of different amylose and amylopectin pools revealed that increased amylose content resulted in the decrease of RC of short amylopectin chains (AP1, DP < 36), and the increase of Rh and RC of long amylopectin chains (AP2, DP > 36). Fluorophore-assisted carbohydrate electrophoresis (FACE) analysis showed the average chain lengths of defined structures of fa, fb1, and fb3, and the content of fb3 were increased with the amylose content and at AC content of 43%, the chain lengths decreased with the amylose content. The relative contents of fa and fb1and the degree of branching had the converse trends. Hence, HA-2, having an AC content of 43%, was the tipping point for these structural changes. Small angle X-ray scattering (SAXS) and its normalized 1D correlation function and SAXS scattering curve parametric fitting showed that the crystalline lamellar thickness was negatively correlated with proportion of short amylose chains (AM1, 100 <DP ≤ 150). The Bragg lamellar repeat distance was positively correlated to Rh of the intermediate amylose chains (AM2, 150< DP ≤ 800). The amorphous lamellae thickness was positively correlated with the Rh of long amylose chains (AM3, 800 <DP ≤ 40,000). The positive correlation between Rh of AM2 on the Gaussian peak area and the scattering invariant suggests AM2 chains stabilize the lamellar structure. Both the digestion rate of the digestible starch as well as the resistant starch content were positively correlated with amylose content. Pearson correlation analysis demonstrated that longer amylopectin chains and lower content of AP1 chains were positively correlated with the digestion rate.

Enzymatic digestion of amylose and high amylose maize starch inclusion complexes with alkyl gallates

The interactions between starch and phenolic compounds have a great impact on the physicochemical and nutritional properties of starch-containing foods. One particular form of the interaction is starch-guest inclusion complexation, which is a specific non-covalent interaction formed between starch and guest molecules. This study investigates complexation ability and enzymatic digestibility profiles of amylose and high amylose maize starch (HAMS) inclusion complexes with gallic acid (GA) and alkyl gallates of various chain lengths, including butyl (BG), octyl (OG), dodecyl (DG), hexadecyl (HG), and octadecyl (SG) gallates. The formation of inclusion complex was examined by complementary techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The digestibility profiles, represented as rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) contents, were obtained through simulated in vitro enzymatic digestion assays. The results showed that while GA, BG, and OG were not capable of forming inclusion complex with either amylose or HAMS, gallates with longer alkyl chains were able to form more stable inclusion complexes. Precipitated amylose and HAMS samples without inclusion complex formation contained the lowest RDS and highest SDS + RS, probably due to starch retrogradation. Amylose and HAMS inclusion complexes with long alkyl chain, particularly HG and SG, also possessed the lowest RDS and highest SDS + RS, but higher SDS proportions than the non-complexed starch samples. It was suggested that the inclusion complexes, especially amylose-HG and SG, and HAMS-DG, HG, and SG, might have contributed to the increase in SDS content. The water insusceptibility and high thermal stability of these inclusion complexes helped retard the starch digestion. The resistant yet steady digestion behavior of the starch-gallate inclusion complexes has significant implications in modulating glycemic response, as well as enabling a slow and sustained release of bioactive guest compounds into the gastrointestinal tract.

The effect of amylose on kernel phenotypic characteristics, starch-related gene expression and amylose inheritance in naturally mutated high-amylose maize

High-amylose maize starch has great potential for widespread industrial use due to its ability to form strong gels and film and in the food processing field, thus serving as a resistant starch source. However, there is still a substantial shortage of high-amylose maize due to the limitation of natural germplasm resources, although the well-known amylose extender (ae) gene mutants have been found to produce high-amylose maize lines since 1948. In this context, high-amylose maize lines (13 inbreds and 18 hybrids) originating from a natural amylose mutant in our testing field were utilized to study the correlation between amylose content (AC) and phenotypic traits (kernel morphology and endosperm glossiness), grain filling characteristics, gene expression, and amylose inheritance. Our results showed that AC was negatively correlated with total starch content but was not correlated with grain phenotypes, such as kernel fullness, kernel morphology and endosperm glossiness. Maize lines with higher amylose had a greater grain filling rate than that of the control (B73) during the first 20 days after pollination (DAP). Both starch debranching enzyme (DBE) groups and starch branching enzyme IIb (SBEIIb) groups showed a greater abundance in the control (B73) than in the high-amylose maize lines. Male parents directly predicted AC of F1, which was moderately positively correlated with the F2 generation.