High-amylose Maize Starch Research Articles

Influence of different kinds of fatty acids on the behavior, structure and digestibility of high amylose maize starch-fatty acid complexes.

The formation of starch-lipid complexes is of interest to food processing and human nutrition. Fatty acid (FA) structure is important for the formation and structure of starch-FA complexes. However, there is limited research regarding the complexing behavior between amylose and different kinds of FAs, as well as the relationship between fine structures and digestibility of the formed complexes. This study aimed to investigate the behavior, fine structure, and digestibility of complexes formed between high amylose maize starch (HMS) and FA having various chain lengths and unsaturation degrees. Complexes containing different FA structures showed V6III -type crystals. Complexes containing 18-carbon unsaturated FAs displayed significantly higher complexing index (P < 0.05) than other complexes. Complexes containing 12-carbon FAs and 18-carbon FAs with one unsaturation degree showed a higher degree of structural order and resistant starch (RS) content than other complexes. The 12-carbon FAs exhibited a higher binding degree with helical cavity of amylose than other FAs. Additionally, 10-carbon and 18-carbon saturated FAs tended to combine with HMS outside amylose helices more than other FAs. Laser confocal micro-Raman imaging revealed that the physically embedded 10-carbon and 18-carbon saturated FAs showed heterogeneous distribution in complexes, and that the complexed 18-carbon FAs with one unsaturation degree exhibited homogeneous distribution. The behavior, structural order and digestibility of complexes could be regulated by FA structure. The 12-carbon FAs and 18-carbon FAs with one unsaturation degree were more suitable for the production of HMS-FA complexes with higher structural order and RS content than other FAs. © 2022 Society of Chemical Industry.

Starch acylation of different short-chain fatty acids and its corresponding influence on gut microbiome and diabetic indexes

This study investigated correlations between gut microbiota and type 2 diabetic (T2D) indexes using either native resistant starch (RS, from high amylose maize starch, HAMS) or acylated starch via short-chain fatty acids (SCFAs) acylation. Compared to HAMS, consumption of acylated starch achieved a greater impact on the improvement of T2D indexes in term of body weight loss, fasting blood glucose, serum insulin level and amino acid metabolism. Intervention with acylated starches alleviated metabolism disorders and modified the gut microbiota. This study found all the acylated starch significantly enhanced the growth of SCFAs-producing bacteria compared to its native HAMS, and this change was highly consistent with their corresponding SCFAs concentration both in serum and fecal samples. This is the first reported to reveal that propionylated HAMS promoted the abundance of Bifidobacterium, while acetylated and butylated HAMS benefited the enrichment of Coprococcus, Butyricimonas and Blautia, which may indicate their different intervention pathway.

Modification of granular waxy, normal and high-amylose maize starches by maltogenic α-amylase to improve functionality

Maltogenic α-amylase (MGA) was used to modify granular waxy (WMS), normal (NMS), and high-amylose maize (HAMS) starches for improved functional attributes. MGA treatment for 24 h shortened the amylopectin branch chains of WMS and NMS, which considerably retarded their retrogradation during cold storage. Due to the effective degradation at both granular and molecular levels, MGA modification markedly diminished the pasting viscosities of WMS and NMS. The MGA treatment increased the resistant starch (RS) content of cooked NMS from 2.6% to 7.3%, resulting from the formation of retrograded amylose in MGA-modified NMS during incubation at 37 °C in the Englyst Assay. Different from the effective hydrolysis on WMS and NMS using an “inside-out” pattern, MGA hydrolyzed HAMS to a very low degree through “surface pitting”, thus showing limited influence on its functionality. The reported novel findings will be meaningful for utilizing MGA to develop “clean-label” starch ingredients with enhanced functional properties.

Impact of amylose from maize starch on the microstructure, rheology and lipolysis of W/O emulsions during simulated semi‐dynamic gastrointestinal digestion

SummaryThis study aims to examine the microstructure, rheology and lipolysis of water‐in‐oil (W/O) emulsions (40 wt.%) prepared with or without (Control) the addition of normal (NAM) and high amylose (HAM) maize starch during simulated digestion in a semi‐dynamic gastrointestinal tract (GIT) model. Microstructural examinations showed modification in initial W/O emulsion droplets to multiple W1/O/W2 droplets during in vitro digestion. This is in line with the rheological results, where the shear viscosity and moduli in the oral phase were remarkably reduced after entering the intestinal phase. In comparison to control and NAM emulsions, HAM emulsions showed a more compact and continuous network structure and greater viscosity and elastic modulus throughout GIT digestion. These results support lipolysis, where fewer free fatty acids were released in the HAM emulsion (70%) than in the control (86%) and NAM (78%) emulsions. This work has provided an in‐depth understanding of the digestion of W/O emulsions as influenced by amylose content, which is meaningful for the development of low‐fat products with reduced lipid digestibility.

Stabilizing emulsions using high-amylose maize starch treated by solvothermal process

This paper proposes a method to modify high-amylose maize starch (HAMS) with lauric acid in an ethanol solvothermal system to prepare a cold-water swelling esterified starch (M-HAMS). Using M-HAMS as a granule stabilizer, oil-in-water Pickering emulsions were prepared, and factors affecting the oxidation stability of emulsion, such as granule content, oil-water ratio, pH value, and NaCl concentration, were studied. Atomic force microscopy (AFM) analysis showed that M-HAMS granules swell into dense molecular chains liking a three-dimensional network barrier in the emulsion, which increases the viscosity of continuous phase and prevents the oil droplets from contacting the pro-oxidant in the water phase, thus reducing the peroxide value. At the same time, the influence of changes in pH value and NaCl concentration on the viscosity and stability of emulsion is weakened. Therefore, the preparation of M-HAMS granule by ethanol solvothermal is a simple and effective method.

Enhancement of enzymatic resistance in V-type starch inclusion complexes by hydrothermal treatments

Resistant starch (RS) is well known for its health beneficial effects for glycemic control and gut health. In addition to some commonly reported RS types, such as raw high amylose maize starch (HAMS), potato starch, retrograded starch, and cross-linked starch, formation of starch inclusion complexes could also contribute to an increase in RS content. In this study, V type starch inclusion complexes with two guest compounds, ascorbyl palmitate (AP) and palmitic acid (PA), were formed using the novel “empty” V type method, and hydrothermal treatments were performed to further enhance the RS contents. Complimentary X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques were conducted to assess the crystalline structure and thermal properties of the raw and treated inclusion complexes, and simulated in vitro enzymatic digestion was performed to study the structure-digestibility relationship in the treated samples. Although the raw inclusion complex samples exhibited minimal RS contents, all the treatments retarded starch digestion by increasing RS or SDS levels. For both V6h-AP and V6h-PA inclusion complexes, annealing followed by long-term strong acid hydrolysis treatment (ANN-ACH) resulted in the greatest increase in RS content, followed by strong ACH treatments alone. In addition, while presenting a comparable RS level as traditional RS2, the ANN-ACH treated V6h-AP inclusion complex retained a V type crystalline structure, indicating its great potential as a novel type of RS, i.e., RS5. The study findings could have practical implications for the design and modification of RS-containing food for the control and modulation of glycemic response.

Effect of Lotus Seed Resistant Starch on Lactic Acid Conversion to Butyric Acid Fermented by Rat Fecal Microbiota.

The aim was to investigate the effect of lotus seed resistant starch (LRS) on lactic acid (LA) conversion to butyric acid (BA) fermented by rat fecal microbiota to construct an acetyl CoA pathway. According to growth curves, the microbiota compositions at 10 and 36 h were further analyzed. The microbiota in the LRS group had higher richness and diversity compared to glucose (GLU) and high amylose maize starch (HAMS). Moreover, LRS and isotope LA promoted the growth of Lactobacillus and Bifidobacterium, promoted BA production, and inhibited the growth of Escherichia-Shigella. The BUT pathway played a dominant role in three groups. At 10 h, Escherichia-Shigella and Bifidobacterium showed a negative correlation with BUT and a positive correlation with BUK, whereas Escherichia-Shigella, Allobaculum, Bifidobacterium, and Ralstonia showed a positive correlation with BUT and BUK at 36 h. [3-13C] LA was converted to [4-13C] BA by the isotope labeling technique. Finally, LRS promoted LA conversion to BA mainly by the BUT pathway in intestinal microbiota, especially including Allobaculum, Bifidobacterium, and Ralstonia.

Temperature of plasma-activated water and its effect on the thermal and chemical surface properties of cereal and tuber starches

High amylose and waxy starches from maize and potato were incubated with plasma-activated water (PAW) at 25 °C, 60 °C, and 80 °C temperatures to investigate PAW treatment effects on the starches' properties. At 60 °C incubation temperature, the starches were basically annealed with PAW. Annealing starches with PAW significantly increased (p < 0.05) the gelatinization parameters except for the enthalpy of gelatinization of waxy potato starch. Furthermore, starch swelling power significantly decreased while the water absorption capacity and solubility increased significantly when incubated at 80 °C. X-ray photoelectron spectroscopy (XPS) analysis showed the oxidation of C–C/C–H and C–O into carboxyl groups in waxy and high amylose maize starches incubated with PAW at 60 °C and 80 °C, respectively. In addition, cross-linking was observed in waxy maize and high amylose potato incubated with PAW at 80 °C and 25 °C, respectively. Overall, the results indicated PAW temperature is an important factor in modifying cereals and tuber starches with PAW.

Ordered structure of preformed V-amylose inclusion complex with 5-heptadecylresorcinol

5-Heptadecylresorcinol (ARs-17) is an amphiphilic phenolic lipid in grain bran with multiple bioactivities. In this study, the relationship between the crystalline structure, thermostability, morphological properties and in vitro digestibility of high amylose maize starch (HAMS) and preformed V-amylose (V6a, V6h, V7a, V7h, V8a, V8h) inclusion complexes with ARs-17 were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscope (SEM). XRD and FTIR results revealed that both HAMS and V-amylose could form V6-type crystalline inclusion complexes with ARs-17, and the hydrophobic alkyl chain of ARs-17 located in the amylose helix cavity, while the hydrophilic phenolic hydroxyl group of ARs-17 located outside the helix. DSC analysis demonstrated that the complexation of V-amylose and ARs-17 was beneficial to the formation of stable type VIIb complexes with higher peak temperature over 140 °C, while the endothermal peak of HAMS-ARs-17 inclusion complex was only around 115 °C. SEM images detected that V-amylose and their complexes were spherical shape with the close-packed structure and aggregated together. By parameterizing digestion kinetics through logarithm-of-slope analysis (LOS) plot fitting, V6a-ARs-17 and V6h-ARs-17 inclusion complexes exhibited the lowest digestibility. This study suggests the great potential to apply V-amylose as functional ingredient for improving both processing and digestion stability of alkylresorcinols and thereby enhancing its bioaccessibility.

Inhibitory Effect of Ascorbic Acid on in vitro Enzymatic Digestion of Raw and Cooked Starches.

Ascorbic acid, also known as vitamin C, was previously reported to inhibit the activity of pancreatic α-amylase, the primary digestive enzyme for starch. A major implication of such inhibition is a slowed rate of starch digestion into glucose, which thereby reduces postprandial hyperglycemia. The aim of this study was to explore the inhibitory effects of ascorbic acid at various concentrations on the in vitro digestion of high amylose maize starch (HAMS) and potato starch (PS) in both raw and cooked conditions. Resistant starch (RS) content, defined as the starch that remained after 4 h of simulated in vitro enzymatic digestion, was measured for the starch samples. Upon the addition of ascorbic acid, the RS contents increased in both raw and cooked starches. Cooking significantly reduced the RS contents as compared to raw starches, and less increase in RS was observed with the addition of ascorbic acid. The inhibitory effect of ascorbic acid on the digestion of raw starches showed a dose-dependent trend until it reached the maximum extent of inhibition. At the concentrations of 12.5 and 18.75 mg/mL, ascorbic acid exhibited the most potent inhibitory effect on the in vitro starch digestion in raw and cooked conditions, respectively. Overall, our results strongly indicate that ascorbic acid may function as a glycemic modulatory agent beyond other important functions, and its effects persist upon cooking with certain concentrations applied.

Resistant Starch Consumption Effects on Glycemic Control and Glycemic Variability in Patients with Type 2 Diabetes: A Randomized Crossover Study.

We previously observed beneficial effects of native banana starch (NBS) with a high resistant starch (RS) content on glycemic response in lean and obese participants. Here, we aimed to determine the effects of NBS and high-amylose maize starch (HMS) on glycemic control (GC) and glycemic variability (GV) in patients with type 2 diabetes (T2D) when treatments were matched for digestible starch content. In a randomized, crossover study, continuous glucose monitoring (CGM) was performed in 17 participants (aged 28–65 years, BMI ≥ 25 kg/m2, both genders) consuming HMS, NBS, or digestible maize starch (DMS) for 4 days. HMS and NBS induced an increase in 24 h mean blood glucose during days 2 to 4 (p < 0.05). CONGA, GRADE, and J-index values were higher in HMS compared with DMS only at day 4 (p < 0.05). Yet, NBS intake provoked a reduction in fasting glycemia changes from baseline compared with DMS (p = 0.0074). In conclusion, under the experimental conditions, RS from two sources did not improve GC or GV. Future longer studies are needed to determine whether these findings were affected by a different baseline microbiota or other environmental factors.

Cationized high amylose maize starch films reinforced with borax cross-linked nanocellulose

In this study, a novel strategy for modifying nanocellulose (NC) by borax cross-linking was developed, and the obtained borax modified nanocellulose (BNC) was incorporated into cationized high amylose maize starch (CS) films to evaluate the applicability. Cellulose molecules were successfully cross-linked by boron ester bonds, and the original crystal type and basic chemical structure were not changed. Compared with NC, the relative crystallinity of BNC was slightly increased, and the thermal stability was obviously enhanced. Addition of NC and BNC to CS films significantly improved their tensile strength and water resistance. The dispersion of nanocellulose in CS films was effectively improved by borax cross-linking modification. CS/BNC films showed higher mechanical and water resistance properties compared with CS/NC films. Compared with pure CS film, tensile strength of the composite film with 6 wt% BNC increased about 4.0 times, and its water-vapor permeability decreased about 37%. The novel strategy for preparing BNC by using boron ester bonds will provide a potential approach for the development of starch films with desirable properties.

Optimal Extraction Methods for High Amylose Maize Starch Studied by Size-Exclusion Chromatography (SEC) and Small-Angle X-ray Scattering (SAXS)

Optimal Extraction Methods for High Amylose Maize Starch Studied by Size-Exclusion Chromatography (SEC) and Small-Angle X-ray Scattering (SAXS)

Complexation ability and physicochemical properties of starch inclusion complexes with C18 fatty acids

Starch, especially its amylose component, is well-known to form inclusion complexes with a variety of small molecules such as fatty acids. The structure of the lipid guest could affect its complexation ability and other properties such as thermal stability. The present study aimed to investigate the complexation ability and the physicochemical properties of high amylose maize starch (HAMS) inclusion complexes with C18 fatty acids of various numbers and positions of double bonds, including octadecanoic (stearic, SA), (Z)-octadec-9-enoic (oleic, OA), (E)-octadec-9-enoic (elaidic, EA), (9Z,12Z)-octadeca-9,12-dienoic (linoleic, LA), (9Z,12Z,15Z)-octadeca-9,12,15-trienoic (α-linolenic, ALA), and conjugated linoleic acids (CLA). Two complexation methods were used, which are the DMSO method and the “empty” V-type method. The formation, structural characteristics, and thermal properties of inclusion complexes formed were examined by complementary techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. As the guest fatty acid became more unsaturated and as the number of double bonds increased, the dissociation temperatures of HAMS-fatty acid inclusion complexes formed decreased with either complexation method. The DMSO method resulted in the formation of Form I inclusion complexes only, whereas the “empty” V-type method promoted the formation of Form II inclusion complexes with higher thermal stability. In addition, ethanol concentration was found to influence the formation of inclusion complexes when using the “empty” V-type method, and intermediate concentrations were more favorable to maintain a stable and flexible amylose helical structure to form inclusion complexes with higher crystallinity and thermal stability.

Complexation between High-Amylose Starch and Binary Aroma Compounds of Decanal and Thymol: Cooperativity or Competition?

The use of combinations of aroma compounds is common in many food and cosmetic applications. To investigate the binding behavior between high-amylose maize starch and binary aroma combinations of decanal and thymol, starch-aroma inclusion complexes (ICs) were prepared by a one-step or two-step method with different concentrations and orders of addition. The thymol molecule induced the starch chain to form a larger helical cavity and was more likely to form hydrogen bonds with solvents. The encapsulation efficiency and loading efficiency of starch-thymol ICs were always higher than those of starch-decanal ICs, independent of the aroma concentration and addition order in binary aroma ICs. However, starch-decanal ICs prepared in the presence of thymol encapsulated more decanal than in the absence of thymol. The V6I-type crystals formed by starch-decanal ICs and the V6III-type crystals formed by starch-thymol ICs were both present in binary aroma ICs, resulting in a less-ordered structure and lower thermal transition temperatures. In summary, the complexation between binary aroma compounds and starch exhibited both cooperative and competitive binding behaviors. The synergistic effects between decanal and thymol provide guidance in enhancing the aroma encapsulation in starch carriers.

Inhibition of in vitro starch digestion by ascorbyl palmitate and its inclusion complex with starch

Since starch is the major energy source of the human diet, retarding starch digestion could serve as an effective way for modulating glycemic response and for the prevention and treatment of obesity. In this study, a dietary bioactive compound, ascorbyl palmitate (AP), was evaluated as a potential inhibitor in the digestion of raw, cooked, and retrograded high amylose maize starch (HAMS) and potato starch (PS). The inhibitory effect of AP was compared with that of palmitic acid (PA), without the ascorbyl group. In addition, HAMS inclusion complexes with AP and PA were formed and treated by annealing (ANN), acid hydrolysis (ACH), and the combination of both. Upon the addition of AP, the resistant starch (RS) contents in raw, cooked, and retrograded starches were increased significantly, indicating the inhibitory effect of AP against starch digestion. Although both HAMS-AP and HAMS-PA inclusion complexes exhibited minimal RS contents, all the hydrothermal treatments enhanced the RS contents in both inclusion complexes, marking their potential to serve as a new type of RS, i.e., RS5. Among the treatments, ANN followed by ACH (ANN-ACH) was most effective to retard starch digestion by increasing RS contents. The study findings could have practical implications in designing functional starch-based ingredients and increasing their nutritional value.

Manipulation of the internal structure of starch by propionyl treatment and its diverse influence on digestion and in vitro fermentation characteristics

High amylose maize starch (HAMS) and waxy maize starch (WMS) were modified by propionylation and their corresponding physicochemical characteristics, digestion and fermentation properties were studied. The results indicated that two new peaks related to methylene (2.20 ppm) and methyl (0.97 ppm) in the NMR spectrum were formed, indicating the occurrence of propionylation, and this was further confirmed by the formation of a characteristic absorption at 1747 cm−1 in the FTIR spectrum. The propionylation led the modified starch having a lower electron density contrast between the crystalline and amorphous flakes, resulting in the formation of a more compact structure following the increased degrees of substitution (DS). The propionylated starch also had a higher thermal stability and hydrophobicity. These structural changes increased the content of resistant starch (RS) and reduced the predicted glycemic index. More importantly, the gut microbiota fermentation properties indicated that the propionylation of the starch can not only increase the yield of propionate, but also increase the concentration of total short-chain fatty acids (SCFAs). This study highlights a new approach to significantly enhance the RS content in starch, together with an increased SCFA generation capacity.

Formation of type 3 resistant starch from mechanical activation-damaged high-amylose maize starch by a high-solid method

This study focused on constructing a high-solid reaction system to prepare type 3 resistant starch (RS3) with high-amylose maize starch as raw material by mechanical activation (MA) pretreatment combined with thermal and freeze–thaw treatments. MA pretreatment effectively destroyed the crystal structure and molecular structure of native starch. MA damaged starch with a certain viscosity could form dough with a small amount of water to construct a starch continuous phase system. RS content increased with the damage levels of starch as the formation of double helix structure, attributed to that the molecules of MA damaged starch could be easy to move and form recrystallization structure. Thermal and freeze–thaw treatments contributed to strong interaction of starch–water and the re-formation of internal crystal structure of MA damaged starch to form RS3. This study provides insight into the development of a highly effective approach for large scale production of resistant starch.

In vitro fecal fermentation outcomes of starch-lipid complexes depend on starch assembles more than lipid type

The human gut microbiota are mostly regulated and stabilized by available macro-nutrients (carbohydrates, proteins and lipids) excursed to colonic fermentation. Resistant starch (RS) has been shown to be metabolized to specific short-chain fatty acids (SCFAs) in the colon associated with proven health benefits. However, the in vitro fecal fermentation outcomes of starch-lipid complexes (i.e., type 5 RS) and its regulation mechanism on gut microbiota are least understood. In this study, debranched high-amylose maize starches complexed with saturated fatty acids (SFAs) were in-vitro fermented by human fecal inocula and evaluated for fermentation rate, beneficial metabolite profiles as well as changes in microbiota composition. The fermentation rate of all starch-lipid complexes tested was similar and slow throughout the whole fermentation process. At the end of fermentation, the propionate concentration was significantly different between starch-lipid complex samples prepared with various SFAs. No significant difference was observed at the first three fermentation time points for the butyrate concentration, with the final concentration range of 27–33 mM. Starch-lipid complexes significantly increased the relative abundance of some beneficial gut microbiota such as Roseburia and Prevotella, and showed a closer distance with high-amylose maize starch and debranched starch rather than SFAs from the principal component analysis. Furthermore, compared with starch-lipid complexes, lauric acid and myristic acid promoted the increase of some apparently harmful gut microbiota, including Bilophila, Fusobacterium and Dialister, while palmitic acid and stearic acid did not show similar phenomenon.

In vitro Digestibility Profiles of Different Types of Resistant Starch With Bioactive Guest Inhibitors

Abstract Objectives Retardation of starch digestion is an effective way of optimizing glycemic response. As the non-digestible portion of starch, resistant starch (RS) is associated with several beneficial effects such as regulating blood glucose level and improving gut health. Although all types of RS demonstrate such health benefits, different subtypes and structures may lead to variations in the digestibility profile. The aim of this study was to investigate and compare the in vitro digestibility of type 2 RS (RS2), type 3 RS (RS3), and novel type 5 RS (RS5) produced by starch inclusion complexes with ascorbyl palmitate (AP) and palmitic acid (PA) as potential inhibitors or guest compounds. Methods Two RS2 samples (high amylose maize starch, HAMS; potato starch, PS) in both raw and cooked forms, and RS3 samples produced by retrogradation of the two starches were tested for in vitro enzymatic digestion. AP and PA were either added during the digestion of RS2 and RS3 samples as potential inhibitors or processed to form inclusion complexes with starch prior to digestion as guest compounds of RS5. Starch digestibility profiles, represented by rapidly digestible starch (RDS), slowly digestible starch (SDS), total digestible starch (TDS), and RS contents, were determined. Results Cooking significantly increased the digestibility of RS2, while retrogradation (formation of RS3) inhibited the digestion by increasing the SDS and RS contents. The addition of AP significantly inhibited the in vitro digestion of RS2 (both raw and cooked HAMS and PS) and RS3 (retrograded HAMS and PS). The digestibility profile of RS5 produced by forming starch inclusion complexes with AP and PA was comparable to that of RS3, which exhibited higher SDS and RS contents as compared to cooked RS2. Conclusions AP as a bioactive guest compound could inhibit the in vitro digestion of raw and cooked RS2 and RS3. RS5 produced by forming starch inclusion complexes with AP and PA presented comparable digestibility with RS3, and higher SDS and RS contents as compared to cooked RS2. Since raw RS2 is not normally consumed in daily life, RS3 and RS5 could serve as better choices for daily consumption. In addition, adding certain bioactive food components could compensate for RS loss, suggesting a practical way of modulating glycemic response. Funding Sources University of Alabama Emerging Scholar Program and Faculty Start-up Fund.