Amylomaize Starch Research Articles

Gelatinisation of starches of different amylose/amylopectin content. A study by differential scanning calorimetry

Differential scanning calorimetry has been used to study the gelatinisation of waxy maize, wheat and potato starches as a function of water content. Despite the good straight-line plots obtained when the data were fitted using the Flouy-Huggins equation, some doubt exists over the applicability of this equation, since it is unclear whether melting of the ‘last’ crystallite occurs (effectively) at equilibrium or is controlled by plasticisation of the amorphous regions of the granules as a result of a glass transition. The gelatinisation of these three starches and, in addition, amylomaize starch, was examined at an intermediate water content (v 1 0·67, 57 % water). The most appropriate model for gelatinisation includes a glass transition, perhaps due to plasticisation of the amorphous amylose fraction, and two phase transitions within amylopectin; M1, assigned to the disordering of amylopectin crystallites, preceded by G due to the disordering of ‘double-helices’ associated with short-range order. The enthalpies of gelatinisation of amylomaize, wheat and waxy maize starches ranked in order of amylopectin content. In contrast, potato starch had the largest gelatinisation enthalpy of all the starches even though its amylopectin content was similar to that of wheat starch. The reason for this may lie in a high proportion of ‘double helical’ material with only short range order for this starch, compared with other starches.

Structural features of amylomaize starch: Components of amylon 50 starch.

A commercial amylomaize starch, Amylon 50, was sub-fractionated with 1-butanol, and the two fractions (PF and SF) derived from the precipitate and supernatant fluid were characterized. The precipitated fraction (PF) was composed of amylose and amylomaize-specific amylopectin. An intermediate material was found in the supernatant fluid fraction (SF). Some characteristics of the intermediate material were consistent with those of a low-molecular-weight material previously isolated from amylomaize starch [T. BABA and Y. ARAI: Agric. Biol. Chem., 48, 1763-1775 (1984)]. The results of the present study, involving chromatographic separation with or without debranching treatment, demonstrate that Amylon 50 is composed of approximately 20% of amylose, 40% of amylomaize-specific amylopectin and 40% of the intermediate material.

Structural features of amylomaize starch: Components of Amylon 70 starch.

The components of Amylon 70 starch were examined quantitatively. The Amylon 70 contained approximately 25% of amylose and 20% of amylomaize-specific amylopectin. The amount of the major component, with a lower molecular weight than that of amylose, was estimated to be almost 55%. Some properties of the low-molecular-weight material were consistent with those of the intermediate material from the other amylomaize starches described previously.

Resistant starch: Formation and measurement of starch that survives exhaustive digestion with amylolytic enzymes during the determination of dietary fibre

Heat-processed foods can contain appreciable amounts of resistant starch (RS) that has the ability to survive prolonged incubation with a-amylase and other amylolytic enzymes. The occurrence of RS has important implications for dietary fibre (DF) determination and, possibly, for human bowel physiology also. Studies using cereal and potato starches have identified three key factors that influence yields of RS after heat-processing, i.e. amylose content, processing temperature and water content. The highest yields of RS (20–34% of total dry weight) were obtained from amylomaize starches, either raw or processed, and from amylopectin starches (32–46% RS) after incubation with α-(1→6)-debranching enzyme (pullulanase) followed by heat-processing. In contrast, the lowest yields of RS (0⁗2–4⁗md2%) were obtained from intact (i.e. non-debranched) amylopectin starches, with or without heat-processing. Yields of RS from wheat starch were affected primarily by processing temperature, reaching levels of about 9% in a single cycle of autoc1aving at 134°C with excess water and subsequent cooling (cf. levels of less than 1% in uncooked wheat starch) and higher levels still (about 15%) after five repeated cycles of autoclaving and cooling. A similar increase in yields of RS was seen in dilute (1%) starch suspensions that were subjected to repeated cycles of heating to 100°C, followed by cooling and storage. The time of storage after gelatinisation was only important in these dilute systems: levels of RS in freshly prepared concentrated starch gels (typically 57–67% H 2 O) or in white bread did not alter significantly on storage.

Effects of Amylomaize Starch on Mineral Metabolism in the Adult Rat: Role of the Microflora

The effects of amylomaize starch on rat mineral metabolism were studied. To elucidate the role of bacterial fermentation, the effects of amylomaize starch were compared in germfree (GF) and conventional (CV) rats. A purified diet, sterilized by irradiation and containing either maize starch (M) or amylomaize starch (A), was fed to the rats. Feed intake was similar in all groups of rats except GF rats fed amylomaize starch ad libitum, whose feed intake was higher. One group of GF rats received amylomaize starch in restricted amounts (pair-fed rats). A balance study of energy, nitrogen and minerals (Ca, P, Mg, Na, K, Fe, Mn, Zn and Cu) was performed. Apparent absorption of Mg, P, Na, K and Zn (expressed as a percentage of the amount ingested) was lower in GF rats fed amylomaize starch than in GF rats fed maize starch. Since feed intake was higher in GF rats fed amylomaize starch ad libitum than in rats fed maize starch, mineral absorption (expressed in milligrams per day) was not reduced in rats fed ad libitum, whereas it was reduced in pair-fed rats. Mineral retention was similar in GF rats fed ad libitum, but was reduced in pair-fed rats. In CV rats fed amylomaize starch, cecal weight and cecal volatile fatty acids concentration were higher than those in CV rats fed maize starch. Apparent absorption of N and P was lower and that of Ca, Mg and Fe was higher in CV rats fed amylomaize starch than in rats fed maize starch. The results for GF rats suggest that amylomaize starch is likely to reduce apparent digestibility of some minerals. However, in CV rats, starch fermentation by the microflora modifies the effect of amylomaize starch on mineral metabolism.

Increase in the ileal absorption rate of sodium taurocholate in germ-free or conventional rats given an amylomaize-starch diet.

Twenty germ-free and twenty conventional male Fischer 344 rats, 3 months old, were fed ad lib. diets based either on normal or on amylomaize starch for 1 month. The absorption rate of sodium taurocholate, 25 mmol/l, was determined in vivo in jejunal or ileal segments. Each determination included five rats. Jejunal absorption rate was not modified either by the amylomaize-based diet or by the digestive microflora. Ileal absorption rate was slightly higher in germ-free than in conventional rats. Ileal absorption rate was largely increased by the amylomaize-based diet. This increase was slightly larger in germ-free rats than in conventional rats. It is suggested that dietary amylomaize starch has an action on the active absorption process of bile acid.

Structural features of amylomaize starch, Part III. Structural characterization of amylopectin and intermediate material in amylomaize starch granules.

The fine structures of amylopectin and intermediate material characteristic of amylomaize starch were investigated by chemical and enzymatic means. In comparison with waxy-maize amylopectin, that of amylomaize starch was found to possess a img/ approximately 10 glucose units longer. Unit-chain profiles of waxy and amylomaize amylopectins revealed that the clear difference lay simply in the relative amounts of two unit-chain fractions. By fractionations of debranched β-limit dextrins, it was demonstrated that the img/ of the internal chains in amylomaize amylopectin was 9 glucose units longer than that in waxy-maize amylopectin. In addition, the proportion of maltose and maltotriose fractions in the debranched dextrin for amylomaize amylopectin was noticeably smaller than found for waxy-maize amylopectin. These data suggest a lesser branching frequency of outer branches in amylomaize amylopectin, confirming the previous proposal that this amylopectin has longer inner and outer branches than those of normal...

Treatment of amylomaize starch granules with urea: comparison with normal maize starch

Treatment of amylomaize starch granules with urea: comparison with normal maize starch

Branching enzyme from amylomaize endosperms

Branching enzyme [(1→4)-α- d-glucan:(1→4)-α- d-glucan 6-glucosyltransferase, EC 2.4.1.18] from developing amylomaize endosperms was fractionated by precipitation with ammonium sulfate and separated into two forms by chromatography on DEAE-cellulose. One form was purified to homogeneity, and found to be primarily monomeric with a broad pH-optimum (pH 6.5–8.0), a low activity in Tris-HCl buffer, and a molecular weight of ∼90,000. These properties were similar to those of a branching enzyme from normal maize kernels previously described. The purified enzyme was apparently inhibited by a low concentration of mercury(II) chloride and increasing concentrations of citrate. The K m value of the enzyme was 18 μg/mL for potato amylose. Further purification of another form of amylomaize branching-enzymes implied the possible presence of additional proteins having molecular weights of ∼92,000 and ∼45,000. The total content of branching enzyme in amylomaize endosperm was approximately one-third of that present in normal maize during endosperm development. The results suggest that amylomaize endosperms may contain at least three forms of branching enzyme, and that the decreased content of amylopectin fraction in amylomaize starch may be associated with the decrease in the total content of branching enzyme.

Some structural features of amylomaize starch

Amylomaize starch was sub-fractionated into two components, complexing (C-fraction) and non-complexing (S-fraction) fractions, and properties of the tw

ラット消化管におけるアミロメイズでんぷん粒の消化過程

ラット消化管におけるアミロメイズでんぷん粒の消化過程

Fractionation and Characterization of Dent Corn and Amylomaize Starch Granules

AbstractStarch granules of dent corn and Classes V and VII amylomaizes were fractionated according to size by an aqueous differential sedimentation procedure. The sized fractions were characterized by microscopy and by a modified method for determining their iodine binding capacities. Results show an inverse relationship between granule size and iodine binding capacity in the amylomaizes. Ordinary dent corn does not show this. The percent apparent amylose in the fractions of amylomaize V starch amounted to 40% for the largest size particles and 52% for the smallest ones; for amylomaize VII starch, 46% for the large particles and 70% for the small particles. Dent corn averaged 23% apparent amylose.

Application of Differential Scanning Calorimetry to Starch Gelatinization. II. Effect of Heating Rate and Moisture Level

AbstractThe influence of heating rate on the gelatinization of wheat starch and starch/water ratio on the gelatinization of wheat, maize, waxy maize and amylomaize starches was examined. More rapid heating resulted in a lowering of the onset temperature of gelatinization for wheat starch from 52 °C at 8°C/min to 46 °C at 32 °C/min. A linear relationship was observed between moisture content and gelatinization energy for starch/water ratios between 1 :2 and 2:1. This allowed calculation of the minimum level of water necessary to initiate gelatinization of each starch. These levels were in excess of the water binding capacity for each starch and were 0.45, 0.45, 0.47 and 0.52 g water/g of wheat, maize, waxy maize and amylomaize starches respectively.

Digestion of amylomaize starch granules in rats.

Digestion of amylomaize starch granules in rats.

アミロメイズでん粉のラット消化管内における消化の様相

アミロメイズでん粉のラット消化管内における消化の様相

Gamma Irradiation of High Amylose Corn Starch

Physical and chemical properties were investigated for amylomaize starches, which were irradiated with gamma rays at total doses of from 0.02 to 60 Mrad. 1) Under below a dose of 1 Mrad, although reducing power, iodine absorption and the limits of β-amylolysis were hardly affected, solution viscosity of the all starches used (five varieties) decreased greatly. Among tested starches, amylomaize starches were more resistant to radiation damage than the other. The cause of difference in sensitivity to gamma irradiation which observed between amylomaize and other starches, was further investigated . The results confirmed that this difference was independent of amylose content and the degree of crystalinity of starch. Irradiated starches became soluble in cold water at above a dose of 30 Mrad . Reducing power increased, and absorption peak of the iodine complex was shifted toward shorter wavelength. The findings seemed to indicate molecular degradation . Furthermore, the recognition of glucose, maltose and oligosaccharides as breakdown products evidenced that the irradiation caused hydrolytic cleavage of the starch molecules. 2) The insoluble residues of irradiated starches were characterized by the determination of DP, β-amylolysis and gel filtration of the pullulanase hydrolyzates. DP of insoluble residues from irradiated starches were 30-40. But these residues contained considerable amounts of high molecular weight components eluted at void volume on Sephadex G-50 column . The elution patterns of the pullulanase hydrolysates of these residues on Sephadex G-50 column showed a marked decrease in amylose fraction. But X-ray diffractograms and scanning electron photomicrographs of the residues did not show a significant changes as compared with those of original starches. The properties of insoluble residues from irradiated starches were compared with those of Nageli amylodextrins and of a-amylase treated starches prepared from non-irradiated starches. The results obtained indicated that the residues differed significantly from amylodextrins and α-amylase treated starches in characteristics . These findings suggested that the starch granules were destroyed at random in both crystalline and amorphous parts by gamma irradiation . 3) In vitro digestion of amylomaize starch granules with pancreatic a-amylase was improved with increasing radiation dose levels. But in vivo digestibility of this starch in rats showed a tendency to be lowered by irradiation, and concomitant increase in weight of feces and cecum contents was also observed. From the results in vivo observation, it seemed that starch granules on the irradiation received some structural modification, in which they could not be cleaved by amylolytic enzymes of digestive tract.

Partial Digestibility of Cooked Amylomaize Starch in Humans and Mice

AbstractA part of ingested high‐amylose starch was indigestible and appeared in feces in both humans and mice. Starch from ordinary corn was not found in feces of either humans or mice. Fecal high‐amylose starch was birefringent, showed no microscopic evidence of enzymic corrosion and had the red polarization color characteristic of high‐amylose starch. The amylose content of fecal starch in both humans and mice was in the range 40 to 49% compared with an initial value of 70% in the amylomaize meal.Depending on the amount of amylomaize eaten (in baked muffins), human feces contained from 6 to 11% of high‐amylose starch. Approximately 11% of the high‐amylose starch ingested with 70 g of amylomaize meal (in baked muffins) appeared in the stool.

The Fine Structure of Corn Starches of Various Amylose‐Percentage: Waxy, Normal and Amylomaize

AbstractThe fine structure of high‐amylose corn starches has been studied after dispersion of the starch and fractionation into their components amylose and amylopectin. The resulting amylopectin fraction reported in the literature possesses anomalous properties with regard to the waxy and normal amylopectin. However, the experimental results obtained by different authors for determining the structure lead to controversal explanations.Therefore, using an enzymic method, which permits the direct examination of the constitutive chains of the starch, the fine structure of the amylopectin of an amylomaize starch (64% amylose) has been investigated and compared with those of waxy and normal starches. The pullulanase – debranched chains are fractionated by gel permeation and their linearity are checked under the action of β‐amylase. The inner chains of the amylopectin fraction are studied after debranching of the β‐limit dextrins. The results show the identity between amylopectins from waxy and normal starches. The amylopectin fraction of amylomaize has its own structure with longer inner chains than those of waxy‐maize amylopectin.

Some Observations on the Stability of Amylose and Amylopectin in Aqueous Solution

AbstractResults are presented for a series of light‐scattering experiments on the stability of the starch components, amylose and amylopectin, in 0.33 M KCl. Potato, regular maize amylose, and the amylose from two amylomaize starches have been studied. The findings are generally in agreement with previous studies in this area, but in the case of amylopectin, contrary to the findings of Čeh and Vene, no retrogradation has been observed.

Studies on Starches of High Amylose‐Content. Part 14. The Fractionation of Amylomaize Starch by Aqueous Leaching

AbstractAmylomaize starch is known to contain an anomalous material which does not conform to the classical definitions of either amylose or amylopectin. A detailed study of this polysaccharide has not yet been carried out, principally because of the difficulty of obtaining it in sufficient quantity. This paper presents a rapid and simple method by which the isolation may be achieved.