High-amylose Maize Starch Research Articles

Formation of inclusion complexes between high amylose starch and octadecyl ferulate via steam jet cooking

Amylose-ligand inclusion complexes represent an interesting approach to deliver bioactive molecules. However, ferulic acid has been shown not to form single helical inclusion complexes with amylose from high amylose maize starch. To overcome this problem a lipophilic ferulic acid ester, octadecyl ferulate, was prepared and complexed with amylose via excess steam jet cooking. Jet-cooking octadecyl ferulate and high amylose starch gave an amylose–octadecyl ferulate inclusion complex in 51.0% isolated yield. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed that a 61 V-type inclusion complex was formed. Amylose and extraction assays showed the complex to be enriched in amylose (91.9±4.3%) and contain 70.6±5.6mgg−1 octadecyl ferulate, although, minor hydrolysis (∼4%) of the octadecyl ferulate was observed under the excess steam jet-cooking conditions utilized. This study demonstrates that steam jet cooking is a rapid and scalable process in which to prepare amylose–octadecyl ferulate inclusion complexes.

Understanding the structural features of high-amylose maize starch through hydrothermal treatment

In this study, high-amylose starches were hydrothermally-treated and the structural changes were monitored with time (up to 12h) using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). When high-amylose starches were treated in boiling water, half-shell-like granules were observed by SEM, which could be due to the first hydrolysis of the granule inner region (CLSM). This initial hydrolysis could also immediately (0.5h) disrupt the semi-crystalline lamellar regularity (SAXS) and dramatically reduce the crystallinity (XRD); but with prolonged time of hydrothermal treatment (≥2h), might allow the perfection or formation of amylose single helices, resulting in slightly increased crystallinity (XRD and DSC). These results show that the inner region of granules is composed of mainly loosely-packed amylopectin growth rings with semi-crystalline lamellae, which are vulnerable under gelatinization or hydrolysis. In contrast, the periphery is demonstrated to be more compact, possibly composed of amylose and amylopectin helices intertwined with amylose molecules, which require greater energy input (higher temperature) for disintegration.

Inclusion complexation of flavour compounds by dispersed high-amylose maize starch (HAMS) in an aqueous model system

This study investigated how hydrophobicity, solubility and the concentration of flavour compounds related to inclusion complexation by dispersed native high amylose maize starch (HAMS). The effect of native lipid on flavour retention and the effect of time (one day to one month) on flavour retention and precipitated starch yield was also examined. Flavour–starch complexation was dependent on the flavour compound hydrophobicity, the flavour concentration in a dose-dependent manner and also influenced by time (increased during storage). Flavour composition also influenced starch complexation; no flavour complexes were reported with limonene by itself but were observed when added in binary flavour mixtures with menthone or thymol. Furthermore, no difference in flavour retention was observed for native and lipid-free starch dispersions. In summary, flavour inclusion complexes with HAMS exhibited cooperativity-type binding behaviour; with a critical ligand concentration needed for a stable physical association between flavour compounds and HAMS.

Molecular rearrangement of waxy and normal maize starch granules during in vitro digestion

The objective of the present study is to understand the changes in starch structures during digestion and the structures contributing to slow digestion properties. The molecular, crystalline, and granular structures of native waxy maize, normal maize, high-amylose maize, and normal potato starch granules were monitored using SEC, XRD, DSC, and SEM. The amylose and amylopectin molecules of all four starches were hydrolyzed to smaller dextrins, with some having linear molecular structure. Neither the A- nor B-type crystallinity was resistant to enzyme hydrolysis. Starch crystallites with melting temperature above 120°C appeared in waxy and normal maize starches after digestion, suggesting that the linear dextrins retrograded into thermally stable crystalline structure. These crystallites were also observed for high-amylose maize starch before and after digestion, contributing to its low enzyme digestibility. On the contrary, the enzyme-resistant granular structure of native normal potato starch was responsible for its low susceptibility to enzyme hydrolysis.

Influence of high-amylose maize starch addition on in vitro starch digestibility and sensory characteristics of cookies

One of the current tendencies in nutrition is to support the consumption of slowly digestiblecereal-based foods with appreciable resistant starch (RS) content. Therefore, experimentalcookies were formulated with normal amylose white wheat flour (NAWW) and increasing levelsofhigh-amylosemaizestarchflour(HAMS)representedbysubstitutionratioof0,25and50%ona total flour (NAWWþHAMS) basis. Chemical composition, in vitro starch digestibility andsensoryevaluation wereinvestigated. Dietary fibre andtotalstarchincreased(p<0.05)whenthelevel of HAMS increased in the recipe for cookies. Both RS and slowly digestible starch (SDS)increased (p<0.05), whereas rapidly digestible starch (RDS) fraction decreased (p<0.05) whenthe level of HAMS increased in the formulation. The rate of starch hydrolysis (k) and thepredicted glycaemic index (pGI) decreased (p<0.05) when the HAMS increased in thecomposite, whereas no difference was reported in the sensory profile and in the overallacceptability of cookies. The higher levels of SDS and RS along with the lower RDS, pGI and kvalues indicated that the substitution of NAWW with HAMS contributed to formulate cookieswith favourably SDS properties without affecting selected sensory characteristics.

Dietary fibre-rich resistant starches promote ammonia detoxification in the human colon as measured by lactose-[15N2]ureide

Three resistant starches (RSs), namely fibre of potatoes (FP), wrinkle pea starch (WPS), and high amylose maize starch (HAMS) with different dietary fibre contents, were supplemented in adults to evaluate their effects on urinary nitrogen and ammonia excretion as well as on faecal nitrogen excretion by means of lactose-[15N2]ureide (15N-LU) degradation. Twenty subjects received a regular diet either without or with the supplementation of FP, WPS, and HAMS in a randomized order. After administration of 15N-LU, urine and faeces were collected over 48 and 72 h, respectively, whereas blood was collected after 6 h. The 15N-abundances were measured by isotope ratio mass spectrometry. In comparison to the dry run, supplementation with RS significantly lowered renal 15N-excretion (dry run: 43.2 %, FP: 34.6 %, WPS: 37.9 %, HAMS: 36.4 %) as well as the corresponding 15NH3-excretion (dry run: 0.08 %, FP: 0.06 %, HAMS: 0.05 %), clearly indicating a reduced colonic nitrogen generation at high dietary fibre intake.

Dietary acylated starch improves performance and gut health in necrotic enteritis challenged broilers

Resistant starch has been reported to act as a protective agent against pathogenic organisms in the gut and to encourage the proliferation of beneficial organisms. This study examined the efficacy of acetylated high amylose maize starch (SA) and butyralated high-amylose maize starch (SB) in reducing the severity of necrotic enteritis (NE) in broilers under experimental challenge. A total of 720 one-day-old male Ross 308 chicks were assigned to 48 floor pens with a 2 × 4 factorial arrangement of treatments. Factors were a) challenge: no or yes; and b) feed additive: control, antibiotics (AB), SA, or SB. Birds were challenged with Eimeria and C. perfringens according to a previously reported protocol. On d 24 and 35, challenged birds had lower (P < 0.001) livability (LV), weight gain (WG), and feed intake (FI) compared to unchallenged birds. Challenged birds fed SA and SB had higher FI and WG at d 24 and 35 (P < 0.05) compared to birds fed the control diet, while being significantly lower than those fed AB. Unchallenged birds fed SA or SB had higher FI at d 24 and 35 compared to those fed the control diet (P < 0.05). Birds fed SB had increased (P < 0.001) jejunal villus height/crypt depth (VH:CD) ratios at d 15, increased ileal (P < 0.001) and caecal (P < 0.001) butyrate levels at d 15 and 24, and decreased (P < 0.01) caecal pH at d 15. Birds fed SA had increased (P < 0.001) ileal acetate content at d 24 and decreased (P < 0.01) caecal pH at d 15. These results demonstrated that dietary acylated starch improved WG in birds challenged with necrotic enteritis. Depending on the acid used, starch acylation also offers a degree of specificity in short chain fatty acid (SCFA) delivery to the lower intestinal tract which improves gut health.

Relationships between amylopectin molecular structures and functional properties of different-sized fractions of normal and high-amylose maize starches

The amylopectin molecular structures and functional properties of different-sized fractions of normal and high-amylose maize starches were investigated and compared in this study. The different-sized fractions of normal starch showed similar amylopectin molecular structures and functional properties. The small-sized fraction of high-amylose starch had significantly higher amylopectin long branch-chain and average branch-chain length than its counterpart medium- and large-sized fractions. The swelling power, gelatinization enthalpy, and hydrolysis and digestion degrees of high-amylose starch significantly decreased with decrease of granule size, and were significantly positively correlated with amylopectin short branch-chain and negatively correlated with amylopectin long branch-chain and average branch-chain length. The gelatinization peak temperature and resistant starch content increased with decrease of granule size, and were significantly positively correlated with amylopectin long branch-chain and average branch-chain length and negatively correlated with amylopectin short branch-chain. The hierarchical cluster analysis indicated that the large-sized fraction of high-amylose starch was significantly different from the medium- and small-sized fractions of high-amylose starch but more relative with normal starch. The above results could provide important information for the applications of different-sized fractions of high-amylose maize starch.

Effect of oil palm phenolics on gastrointestinal transit, contractility and motility in the rat

The effects of a novel water soluble polyphenolics preparation (oil palm phenolics; OPP) on whole gastrointestinal transit, ex vivo proximal and distal colonic contractility and intact expulsion time in the distal colon were examined. Nine weeks of dietary supplementation with OPP at 50 mg gallic acid equivalents (GAE)/rat per day had no effect on gastric emptying compared to the control (AIN-93M), but 30% substituted high amylose maize starch (HAMS) used as a positive resistant starch control, had significantly higher gastric emptying compared to both control and OPP. OPP increased distal colonic contractile response to KCl, PGE2 and angiotensin I compared with the control, whilst HAMS also had similar increased contractile responses. This correlated with faster distal colonic expulsion rates for OPP and HAMS compared with the control. The present study revealed that OPP, like resistant starch, has positive effects on distal colonic contractility and motility with potential putative roles in bowel function and health.

Preparation and characterization of crystalline complexes between amylose and C18 fatty acids

Inclusion complexes were prepared by using high amylose maize starch and C18 fatty acids including stearic, oleic, linoleic, and α-linolenic acids, under reaction conditions varied in temperature (50, 70, and 90 °C), pH (5, 6, 7, and 8), and reaction time (3, 6, 24, and 48 h). Among the four C18 fatty acids tested, stearic acid was most effective and linoleic acid was least effective in the complex formation. The reaction at 90 °C for 24 h provided the maximum recovery (about 75%) in the complex formation using stearic and oleic acids. Linolenic acid, however, could reach its maximum recovery (>70%) when reacted for a shorter period (6 h, 90 °C). Under DSC analyses, the polymorphs formed by linolenic acid appeared more uniform compared to those by other FAs. All the complexes exhibited V type crystalline structures under X-ray diffraction analyses, consisting of type I and type II polymorphs in DSC thermograms when recovered from the reaction mixtures.

Comparative structure of starches from high-amylose maize inbred lines and their hybrids

High-amylose maize starch is of interest because of its health benefits and industrial uses. Hybrid maize is widely grown for the practical and economical value of heterosis. However, starch structure of high-amylose hybrid maize has seldom been reported compared with that of high-amylose inbred maize. In this study, structure of starches from high-amylose maize inbred lines and their hybrids was investigated and compared. Starch granule became smaller in size and more spherical, oval or elongated in shape with increasing amylose content. Hybrid maize starch had lower amylose content and long branch-chain of amylopectin and higher short branch-chain and branching degree of amylopectin than inbred maize starch. Inbred maize starch had B-type crystalline structure with low relative crystallinity, but hybrid maize starch had CB-type crystalline structure and high relative crystallinity. Hybrid maize starch had lower degree of order at a short-range scale on the edge of starch granule than inbred maize starch. Hybrid maize starch had higher double helix content and lower amorphous starch than inbred maize starch. Hybrid maize starch had higher peak intensity and longer Bragg spacing of lamellar structure than inbred maize starch. Hybrid maize starch had lower gelatinization temperature and higher gelatinization enthalpy and swelling power than inbred maize starch. The different structural properties of starches had significant correlation.

Butyrylated starch intake can prevent red meat-induced O6-methyl-2-deoxyguanosine adducts in human rectal tissue: a randomised clinical trial.

Epidemiological studies have identified increased colorectal cancer (CRC) risk with high red meat (HRM) intakes, whereas dietary fibre intake appears to be protective. In the present study, we examined whether a HRM diet increased rectal O(6)-methyl-2-deoxyguanosine (O(6)MeG) adduct levels in healthy human subjects, and whether butyrylated high-amylose maize starch (HAMSB) was protective. A group of twenty-three individuals consumed 300 g/d of cooked red meat without (HRM diet) or with 40 g/d of HAMSB (HRM+HAMSB diet) over 4-week periods separated by a 4-week washout in a randomised cross-over design. Stool and rectal biopsy samples were collected for biochemical, microbial and immunohistochemical analyses at baseline and at the end of each 4-week intervention period. The HRM diet increased rectal O(6)MeG adducts relative to its baseline by 21% (P < 0.01), whereas the addition of HAMSB to the HRM diet prevented this increase. Epithelial proliferation increased with both the HRM (P < 0.001) and HRM + HAMSB (P < 0.05) diets when compared with their respective baseline levels, but was lower following the HRM + HAMSB diet compared with the HRM diet (P < 0.05). Relative to its baseline, the HRM + HAMSB diet increased the excretion of SCFA by over 20% (P < 0.05) and increased the absolute abundances of the Clostridium coccoides group (P < 0.05), the Clostridium leptum group (P < 0.05), Lactobacillus spp. (P < 0.01), Parabacteroides distasonis (P < 0.001) and Ruminococcus bromii (P < 0.05), but lowered Ruminococcus torques (P < 0.05) and the proportions of Ruminococcus gnavus, Ruminococcus torques and Escherichia coli (P < 0.01). HRM consumption could increase the risk of CRC through increased formation of colorectal epithelial O(6)MeG adducts. HAMSB consumption prevented red meat-induced adduct formation, which may be associated with increased stool SCFA levels and/or changes in the microbiota composition.

Effects of stearic acid and gamma irradiation, alone and in combination, on pasting properties of high amylose maize starch

The effects of stearic acid and gamma irradiation on pasting properties of high amylose maize starch (HAMS) were studied. Stearic acid (0%, 1.5%, and 5%) was added to HAMS, and then irradiated at 0, 30, and 60kGy before pasting. Stearic acid increased the paste viscosity of un-irradiated HAMS from 420mPas to 557 and 652mPas for 1.5% and 5% stearic acid, respectively. This observation related well with the formation of type II amylose–lipid complexes, with melting temperatures of about 100–120°C. Gamma irradiation (30 and 60kGy) reduced pasting viscosity of HAMS. Pasting of gamma irradiated HAMS resulted in the formation of type I amylose–lipid complexes, with melting temperatures and enthalpies ranging from 82 to 102°C and 0.22 to 1.85J/g, respectively. Stearic acid addition followed by irradiation creates means of producing different types of amylose–lipid complexes from HAMS for industrial utilization.

Physiochemical properties of highly cross-linked maize starches and their enzymatic digestibilities by three analytical methods

Waxy maize, normal maize and high amylose maize starches were highly cross-linked (CL) with phosphate groups. The CL starches were characterized by phosphorus content, settling volume, gelatinization temperature, pasting curve, X-ray diffraction and microscopy. Their digestibilities were determined by the Englyst, Available Carbohydrate Dietary Fiber (ACDF), and AOAC 991.43 methods where starch digestion with α-amylase was done, respectively, at 37, 80 and 95 °C. The CL waxy maize starch had ∼10% more phosphorus content (0.36% vs 0.32%) than the CL normal and high-amylose maize starches. Total dietary fiber (TDF) levels of the unmodified and CL starches determined by the AOAC and ACDF methods increased with increasing amylose content. The resistant starch (RS) contents of the three CL starches decreased in the order, CL high amylose (85%) > CL waxy (82%) > CL normal (61%) maize starch. The digestibilities of the unmodified and CL maize starches at 80 and 95 °C were positively correlated with their settling volumes at those temperatures, indicating that increased granule swelling decreased TDF levels. Photomicrographs of the starch granules after digestion in the TDF and RS assays showed less internal erosion of granules in CL high-amylose starch compared to CL normal and waxy maize starches.

Resistant starch alters colonic contractility and expression of related genes in rats fed a Western diet.

Dietary fiber shortens gut transit time, but data on the effects of fiber components (including resistant starch, RS) on intestinal contractility are limited. We have examined RS effects in male Sprague-Dawley rats fed either a high-amylose maize starch (HAMS) or a wholemeal made from high-amylose wheat (HAW) on ileal and colonic contractility ex vivo and expression of genes associated with smooth muscle contractility. Rats were fed diets containing 19 % fat, 20 % protein, and either low-amylose maize starch (LAMS), HAMS, wholemeal low-amylose wheat (LAW) or HAW for 11 week. Isolated ileal and proximal colonic sections were induced to contract electrically, or by receptor-independent (KCl) or receptor-dependent agents. Colonic gene expression was assessed using an Affymetrix microarray. Ileal contractility was unaffected by treatment. Maximal proximal colonic contractility induced electrically or by angiotensin II or carbachol was lower for rats fed HAMS and LAW relative to those fed LAMS (P < 0.05). The colonic expression of genes, including cholinergic receptors (Chrm2, Chrm3), serotonin receptors (Htr5a, Htr7), a protease-activated receptor (F2r), a prokineticin receptor (Prokr1), prokineticin (Prok1), and nitric oxide synthase 2 (Nos2), was altered by dietary HAMS relative to LAMS (P < 0.05). HAW did not significantly affect these genes or colonic contractility relative to effects of LAMS. RS and other fiber components could influence colorectal health through modulation of stool transit time via effects on muscular contractility.

Gluten free Maize Cookies Prepared with High-amylose Starch: In Vitro Starch Digestibility and Sensory Characteristics

In an effort to improve gluten-free (GF) cookies overall nutritional aspects, as a means of decreasing the glycemic index and increasing the resistant starch content, experimental GF maize cookies were formulated with a normal amylose GF maize flour mix (NAM) and increasing levels of high amylose maize starch flour (HAM) represented by substitution ratio of 0%, 25% and 50% on a total flour (NAM+HAM) basis. Chemical composition, in vitro starch digestibility and sensory evaluation were carried out. Dietary fibre, total starch and amylose contents increased (p<0.05) when the level of HAM increased in the recipe for GF cookies. Both resistant starch and slowly digestible starch increased (p<0.05), whereas rapidly digestible starch and available starch levels decreased (p<0.05) when the level of HAM increased in the formulation. Slower rate of starch hydrolysis (up to minus 66.0%; p<0.05) and lower predicted glycemic index (up to minus 35.0%; p<0.05) were recorded when HAM increased in the composite. No differences were reported in the sensory profile and in the overall acceptability of GF maize cookies formulated with increasing levels of HAM. Taking together, present in vitro findings suggest that the partial substitution of NAM with HAM contributed to formulate GF maize cookies with slowly digestible starch properties without affecting overall sensory attributes.

Comparison of molecular structures and functional properties of high-amylose starches from rice transgenic line and commercial maize

High-amylose cereal starches are attracting considerable attention because of their potential health benefits. In this study, the molecular structures and functional properties of high-amylose starches from a rice transgenic line and commercial maize were investigated and compared. High-amylose rice and maize starches had apparent amylose contents of 65.6 and 49.4%, respectively. Compared with high-amylose maize starch, high-amylose rice starch had amylopectin with a higher long branch-chain content and average chain length and with a lower short branch-chain content and degree of branching. High-amylose rice and maize starches exhibited C-type and CA-type crystallinity, respectively. The high-amylose rice starch had a significantly higher gelatinization temperature and lower gelatinization enthalpy, swelling power and pasting viscosity than high-amylose maize starch. High-amylose rice starch had a significantly higher resistance to acid hydrolysis and slightly higher resistance to amylase hydrolysis than high-amylose maize starch. Gelatinized and retrograded starches from high-amylose rice had significantly lower rapidly digestible starch and higher resistant starch contents than high-amylose maize starch. These results were also compared with those obtained from normal rice and maize starches. The significantly different molecular structures of rice and maize starches resulted in their different functional properties.

Requirements of phytochemical food composition databases: Comparing current use in food industry and biomedical research

Requirements of phytochemical food composition databases: Comparing current use in food industry and biomedical research

In vitro amylase digestion of extruded maize and high amylose maize starches and evolution of starch structure

In vitro amylase digestion of extruded maize and high amylose maize starches and evolution of starch structure

Molecular, mesoscopic and microscopic structure evolution during amylase digestion of extruded maize and high amylose maize starches.

Extrusion processing of cereal starch granules with high (>50%) amylose content is a promising approach to create nutritionally desirable resistant starch, i.e. starch that escapes digestion in the small intestine. Whilst high amylose content seems to be required, the structural features responsible for the slow digestion of extrudates are not fully understood. We report the effects of partial enzyme digestion of extruded maize starches on amylopectin branch length profiles, double and single helix contents, crystallinity and lamellar periodicity. Comparing results for three extruded maize starches (27, 57, and 84% apparent amylose) that differ in amylase-sensitivity allows conclusions to be drawn concerning the rate-determining features operating under the digestion conditions used. Enzyme resistance is shown to originate from a combination of molecular and mesoscopic factors, including both recrystallization and an increase in very short branches during the digestion process. This is in contrast to the behaviour of the same starches in the granular form (Shrestha et al., 2012) where molecular and mesoscopic factors are secondary to microscopic structures in determining enzyme susceptibility. Based on the structure of residual material after long-time digestion (>8h), a model for resistant starch from processed high amylose maize starches is proposed based on a fringed micelle structure with lateral aggregation and enzyme susceptibility both limited by attached clusters of branch points.