Properties Of Waxy Corn Starches Research Articles

Insight into the improvement in pasting and gel properties of waxy corn starch by critical melting treatments

To improve the pasting and gel properties of waxy corn starch (WCS), the native starch was modified by critical melting (CM) at the onset temperature (TO), peak temperature (TP), and conclusion temperature (TC) (labeled CMO, CMP, and CMC respectively). CM treatments significantly enhanced the thermal stability of the WCS, as indicated by the increase in the peak gelatinization temperature, pasting temperature, and peak time. In addition, after CMP treatment, the storage modulus, hardness, gumminess, springiness, and chewiness of starch gels significantly increased by 43.29 %, 31.14 %, 23.36 %, 8.26 %, and 61.43 %, respectively, and the syneresis rate significantly decreased by 19.69 % (p < 0.05). These results indicated that CMP treatments significantly improved the gelling ability and freeze-thaw stability of the WCS. These results are ascribed to the partial disruption and enhanced rearrangement of the starch crystalline structure. CMP treatment induced the crystalline structure of starch to be partially disrupted and a hard structure was formed on the surface of starch granules. The hard structure in CMP-treated starch supplied more attachment points for crystalline structure rearrangement during gelatinization. Therefore, the above results indicated that CMP treatments can be used to modify starch to improve the pasting and gel properties of starch-based food products.

Profil gelatinisasi, karakteristik mikrobiologi dan sifat fungsional pati jagung ketan terfermentasi [Gelatinization profile, microbiological characteristics and funtional properties of fermented waxy corn starch

Waxy corn (AJU1) is widely cultivated in Gorontalo Province, but its utilization is limited to corn on cobs. A potential diversified product of processed waxy corn to be developed is waxy corn starch. One simple method to improve the functional properties of waxy corn starch is fermentation. This study aimed to determine the effect of different fermentation conditions and fermentation times on the gelatinization profile and functional properties of waxy corn starch. The research method used a completely randomized factorial design with two treatment factors namely fermentation conditions (aerobic and anaerobic) and fermentation time (3, 6, and 9 days). Results showed that the fermentation conditions significantly affected property of waxy corn starch. During fermentation, there was a change in the number of cells of lactic acid bacteria, yeast, and mold. The gelatinization profile of fermented waxy corn starch was to have resistant to stirring and high temperatures and reduced its retrogradation tendency. The fermentation process also changed the functional properties of glutinous corn starch, namely an increase in solubility, swelling, and acidity (decrease in pH).Keywords: aerobic, anaerobic, fermentation, starch, glutinous corn [AJU1]

Development changes in multi-scale structure and functional properties of waxy corn starch at different stages of kernel growth

Waxy corn starch is widely used in food and papermaking industries due to its unique properties. In this work, the structural and functional properties of starch isolated from waxy corn at different stages of kernel growth were investigated and their relationships were clarified. The results showed that with kernel growth, the surface of starch granules became smooth gradually, and the inner growth rings and the porous structure grew and became clear. Meanwhile, the weight-average molecular mass (Mw), root mean square radius (Rg), and average particle size increased while the amylose content decreased, which should account for the decreased pasting temperature (from 71.37 to 67.44 °C) and increased peak viscosity (1574.2 to 1883.1 cp) and breakdown value observed. Besides, the contents of slowly digestible starch (SDS) and resistant starch (RS) in waxy corn starch decreased significantly (from 44.01% to 40.88% and from 16.73% to 9.80%, respectively, p < 0.05) due to decreases in the double helix content, crystallinity, and structural order, and increases in the semi-crystalline lamellae thickness and the amorphous content. This research provides basic data for the rational utilization of waxy corn starch at different stages of kernel growth.

New Insights into Physical, Morphological, Thermal, and Pasting Properties of HHP‐Treated Starches: Effect of Starch Type and Industry‐Scale Concentration

AbstractThe impact of high hydrostatic pressure (HHP) (600 MPa‐20 min) on the physical, morphological, pasting, and thermal properties of waxy corn starch (WCS), normal corn starch (NCS), and wheat starch (WS) at different concentrations (10%, 15%, and 20% w/w) was examined. By applying the HHP, water absorption capacity (WAC) and oil absorption capacity (OAC) of the native starches increased tremendously; however, augmenting the concentration of starches from 10% to 20% w/w cause a slight decrease (for WS and NCS) or increase (for WCS) in WAC and a considerable increase in OAC of the HHP‐treated starches. Morphological analysis shows that by increasing the concentration of HHP‐treated starches, the destruction of starch granules is quite detectable; however, this destruction is lower for NCS and the granules show high resistance to degradation and higher inflation than that of WCS and WS. By employing HHP and augmenting the concentration, the zeta potential of the selected starches increased considerably. Rapid visco analysis revealed that HHP and increasing starch concentration from 10% to 20% caused a remarkable decrease in peak, trough, breakdown, final, and setback viscosities of the starches. The native starches depict higher gelatinization, peak, and conclusion temperatures likewise gelatinization enthalpy than the HHP‐treated starches.

Impact of continuous and repeated dry heating treatments on the physicochemical and structural properties of waxy corn starch

In order to investigate the impact of continuous dry heating treatment (CDHT) and repeated dry heating treatment (RDHT) on the structural and physicochemical properties of the waxy corn starch, the starch was prepared at 140 °C for continuous 20 h or for 5 cycles of heating, respectively. Each cycle lasted 4 h and the interval between each cycle was 1 h of cooling at room temperature. It turned out that RDHT and CDHT caused the aggregation of the starch into big lumps. The crystal type of CDHT and RDHT starches remained A-type, while the relative crystallinity and the short-range molecular order of starch characterized with 1040 cm−1/1018 cm−1 increased during first 2 circulations of RDHT and first 8 h of CDHT afterwards decreased upon the increased duration. After the heat treatment the water absorption index, swelling volume, viscosity and thermal parameters of CDHT and RDHT starches decreased, but the solubility, paste clarity and paste temperature of starches increased compared with native starch. Taken together RDHT has a greater impact on decreasing transmittance of starch paste, weakening the resistance to shear force and increasing retrogradation degree of starch paste compared to CDHT for the same duration.

Molecular, crystal and physicochemical properties of granular waxy corn starch after repeated freeze-thaw cycles at different freezing temperatures

The study was undertaken to reveal the effects of freeze-thaw cycles at different freeze temperature (−20 °C, −40 °C and −80 °C) and the number of freeze-thaw cycles (3, 6, 12, 18, 24 times) on physicochemical and structural properties of waxy corn starch. The number of pores on the surface of starch granules increased, but there was no significant (P < 0.05) effect on molecular weight, transparency, freeze-thaw stability and the crystal structure of starch after repeated freeze-thaw cycle. But the crystallinity intensity decreased after freeze-thaw cycles treatment and a tiny decrease in onset, peak, conclusion temperature and gelatinization enthalpy were found. The RVA analysis exhibited an increase in gelatinization temperatures and a decrease in breakdown and setback value after freeze-thaw treatment, which manifested an increase in the aging and heat resistance of waxy corn starch paste. However, there was no statistical (P < 0.05) difference between different freeze temperatures at the same number of freeze-thaw cycle on physicochemical and structural properties of starch. The obtained data could be helpful in evaluation of the repeated freeze-thaw treatment of waxy corn starch-based foodstuffs and providing the theoretical basic for revealing the effect of repeated freeze-thaw processes in manufacture applications.

Study concerning the influence of different fibres addition in yogurt on its rheological, physicochemical and sensory characteristics

The paper presents a study on the functional properties of waxy corn starches, physicochemically modified. The physical modifications (hydrothermal treatment) allowed to obtain pre-gelatinised starch (Merigel) or untreated starch, of cook-up type (Resistamyl). The chemical modification of starches differentiated them in terms of the degree of cross-linking (low, medium and high) and the level of substitution (medium).The characteristics of changes in the viscosity of starch gels were determined in the function of temperature and time. It was found that with an increase of the degree of cross-linking (low < medium < high) the viscosity of starches of the pre-gelatinisation and cook-up types decreases. At the temperature of +20 °C starch gels of the Merigel type are characterised by a high level of transparency, which may indicate intensively hindered retrogradation at +4 °C, while measurements for samples of the Resistamyl type indicate transmittance values close to zero, similar to those for waxy corn starch. The tendency to syneresis was tested at +4 °C and −22 °C. At +4 °C, the modified starch gels, type Merigel, are characterised by nearly three-fold higher degree of syneresis compared to those from the Resistamyl group. The degree of syneresis of cook-up type gels is small after storage at 22 °C. Starches of the pre-gelatinisation type are characterised by WAI (Water Adsorption Index) values in the range of 981–1207%, and starches of the cook-up type - 196–205%. Higher values of FAI (Fat Adsorption Index) are also noted in the case of the pre-gelatinisation starches (FAI: 194–222%) in relation to the cook-up type starches (FAI: 170–174%). Cook-up starches do not form emulsions. The medium degree of cross-linking of pre-gelatinisation type starches causes a lowering of the value of their specific surface area (SBET), while for the cook-up type starches an increase of that value was observed.

Preparation and characterization of zein thermo-modified starch films

A new method of preparing films from zein thermo-modified starch was presented. According to data of micro-visco-amylography and rheometer, dry heating with zein significantly decreased the pasting properties of waxy corn starch and distarch phosphate, the values of G′ and G″ of starches dry heated with zein decreased, while the loss tangent increased as a function of heating time. Scanning electron microscopy images showed that the surfaces of starch granules became rough after dry heating with zein, suggesting interactions between zein and the granule surface. In films made from mixtures, the starch/zein compatibility was improved through dry heating. Compared with films cast from mixtures of separately heat-treated starch and zein, films made from the starch/zein mixtures heated together possessed higher water contact angle and tensile strength. Simple dry heating with zein could thus be used as a promising modification method for improving the functionality of edible films from starches.

Physicochemical properties of waxy corn starch after three-stage modification

The paper presents a study on the functional properties of waxy corn starches, physicochemically modified. The physical modifications (hydrothermal treatment) allowed to obtain pre-gelatinised starch (Merigel) or untreated starch, of cook-up type (Resistamyl). The chemical modification of starches differentiated them in terms of the degree of cross-linking (low, medium and high) and the level of substitution (medium).The characteristics of changes in the viscosity of starch gels were determined in the function of temperature and time. It was found that with an increase of the degree of cross-linking (low < medium < high) the viscosity of starches of the pre-gelatinisation and cook-up types decreases. At the temperature of +20 °C starch gels of the Merigel type are characterised by a high level of transparency, which may indicate intensively hindered retrogradation at +4 °C, while measurements for samples of the Resistamyl type indicate transmittance values close to zero, similar to those for waxy corn starch. The tendency to syneresis was tested at +4 °C and −22 °C. At +4 °C, the modified starch gels, type Merigel, are characterised by nearly three-fold higher degree of syneresis compared to those from the Resistamyl group. The degree of syneresis of cook-up type gels is small after storage at 22 °C. Starches of the pre-gelatinisation type are characterised by WAI (Water Adsorption Index) values in the range of 981–1207%, and starches of the cook-up type - 196–205%. Higher values of FAI (Fat Adsorption Index) are also noted in the case of the pre-gelatinisation starches (FAI: 194–222%) in relation to the cook-up type starches (FAI: 170–174%). Cook-up starches do not form emulsions. The medium degree of cross-linking of pre-gelatinisation type starches causes a lowering of the value of their specific surface area (SBET), while for the cook-up type starches an increase of that value was observed.

Changes in physicochemical properties of waxy corn starches after harvest, and in mechanical properties of fresh cooked kernels during storage

Changes in the physicochemical properties of waxy corn starches after harvest and in the mechanical properties of cooked fresh kernels during storage were investigated. Immature waxy corn ears from four genotypes were stored at ambient temperature, and starches were isolated from kernels removed at 0, 2, 4 and 6days after harvest. Starch content in the kernels generally increased with storage time, and also significantly differed depending on the genotype. For all the days after harvest, medium granules had the highest contribution to the total starch volume, followed by small and large granules. The average chain length distribution of amylopectin increased in relation to storage time. Starches at harvesting state exhibited the lowest peak viscosity in all four genotypes, which increased relative to postharvest periods. Moreover, the average force behaviours of cooked kernels were greatly affected by storage times after cooking.

Changes in physicochemical properties of waxy corn starches at different stages of harvesting

Starches were isolated from immature waxy corn kernels harvested at 0, 2, 4 and 6 days after optimum stage (DAO) and from mature kernels at 16 DAO. The starch contents showed varied according to genotypes and harvesting stages. The accumulation of starches showed an increasing trend in relation to delayed harvesting time, from the optimum stage until the physiological maturity stage. Among all harvesting stages, medium granules had the highest contribution to the total starch volume (60.8–81.5%), followed by large (5.7–30.1%), and small granules (9.1–15.3%). Average chain length distribution of amylopectin ranged from DP 14.7 to 16.9 for KKU–UB, DP 16.9 to 17.4 for KKU–JD, and DP 5.7 to 30.1 for Violet white. The pasting behaviors of starches were greatly affected by harvesting times. The peak viscosity of starches increased with delayed harvesting until physiological maturity and then decreased until dried kernels at 35 days after pollination.

Pasting and rheological properties of waxy corn starch as affected by guar gum and xanthan gum

Effects of guar (GG) and xanthan (XG) gums (0.35–1.0% w/w) on pasting and rheological properties of waxy corn starch (WCS) (6.0% w/w) were studied. GG had a higher molecular weight but lower intrinsic viscosity than did XG, indicating that the GG chain was more flexible. RVA results indicated that viscosity and pasting temperature of the WCS dispersion during pasting increased with increasing GG or XG concentration. Dynamic viscoelasticity measurements indicated that the WCS/XG mixed pastes exhibited slightly superior viscoelastic properties to the WCS/GG pastes as evidenced by their higher G′ and lower tan δ values. Flow tests showed that the WCS/GG pastes exhibited mainly thixotropic hysteresis loops during a full shear cycle, whereas the WCS/XG pastes showed much less thixotropic and eventually became antithixotropic at high XG concentrations. In-shear structural recovery of the pastes increased more with increasing XG concentrations than did pastes with increasing GG concentrations. The differences in molecular characteristics of the GG and XG chains are hypothesized to be responsible for the above mentioned effects.

アミロース溶液に分散させたモチトウモロコシデンプンのＲＶＡ粘度特性に及ぼすドデシル硫酸ナトリウムの影響

Effects of sodium dodecyl sulfate (SDS) on the pasting properties of waxy corn starch (WCS) dispersed in amylose solution were studied by using a Rapid Visco-Analyzer. At an amylose/WCS ratio of 20/80, the peak viscosity was remarkably increased at the concentrations above 0.67%, although it was not affected below 0.56%. The peak viscosity was decreased with the increasing ratio of amylose up to 25% at 0.37% SDS as well as the control without SDS. The maximum setback viscosity was remarkably increased at the concentrations of SDS above 0.19% up to 0.37% and remained constant thereafter at the fixed ratio of amylose and also increased with the increasing ratio of amylose at the fixed concentration of SDS. These increases in the peak viscosity and maximum setback viscosity of WCS in amylose solution by SDS provided substantial support for the assumption made previously that the increases in the peak viscosity during heating and in the setback viscosity during cooling might be ascribed to the complex formation of amylopectin inside the swollen granules with SDS followed by a further expansion of the swollen granules, and the complex formation of the leached amylose with SDS followed by the gelation, respectively.

Physicochemical properties of waxy corn starch and corn amylopectin illuminated with linearly polarised visible light

Aqueous suspensions (30%) of either waxy corn starch or corn amylopectin were illuminated with visible linearly polarised light ( λ>500 nm) for 5–50 h. Pasting profiles, thermal properties, iodine binding capacity and intrinsic viscosity (in DMSO/water, 90:10) were taken for them after illumination. The illumination for 5, 15, and 25 h was not reflected in overall paste viscosities. Prolonged illumination (50 h) led to significant decrease in the peak and final viscosities. Illumination for 5 h (6.76 J/g), 15 h (7.74 J/g), 25 h. (7.95 J/g), and 50 h (2.85 J/g) decreased the melting enthalpies which for original waxy corn starch was 9.67 J/g. Decrease in intrinsic viscosity, [ η], as compared to that of native waxy corn starch (7.9 dl/g) was observed for the sample illuminated for 15 h (5.9 dl/g). Further illumination led to increase in [ η] values after 25 h (6.6 dl/g) and 50 h (8.0 dl/g). Blue value (BV) measured for the sample illuminated for 5 h (0.106) was higher than for waxy corn starch (0.076). Gradual decrease in BV was observed for samples illuminated for 15 (0.086), 25 (0.071) and 50 h (0.030). No changes in intrinsic viscosity and BV were found in the case of corn amylopectin irrespective of the illumination time. Findings indicate that polarised light induced depolymerisation of starch polysaccharide only if molecules were organised in crystal structures in same manner as in starch granule.

Studies on the Retrogradation and Structural Properties of Waxy Corn Starch

Abstract The protective effect of guanidine hydrochloride (Gu-HCl) on the retrogradation of waxy corn starch (WCS) gel was studied using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and solid-state 1H nuclear magnetic resonance (NMR). The areas of the endothermic peaks on DSC curves attributed to re-gelatinization of WCS gels became small and shifted to lower temperature with increasing Gu-HCl contents; finally, the endothermic peak for WCS gel containing 40% Gu-HCl disappeared, indicating that the WCS gel remained in the gelatinized state. The solid-state 1H NMR and FT-IR spectra for retrograded WCS gels showed significant changes compared with those for gelatinized WCS gels. In the process of retrogradation, these spectral changes should imply the formation of intra- and intermolecular hydrogen bonds of WCS and the increase of free water molecules. However, the 1H NMR and FT-IR spectra for a WCS gel containing 40% Gu-HCl did not show such changes along with the progress of retrogradation. From these results, we found that the retrogradation of starch can be protected by the addition of hydrogen bond-breaking materials, such as Gu-HCl.