Properties Of Waxy Maize Starch Research Articles

Effects of post–silking low temperature on the physicochemical properties of waxy maize starch

Low temperature (LT) at late growth stages is an important abiotic stress that affects the grain end–use quality of summer maize. In the present work, two experiments were conducted to study the effects of LT on the structural and functional properties of starches using two waxy maize hybrids (‘Suyunuo5’ and ‘Yunuo7’). In field trial, the plants were sown on July 1 (normal sowing date) and August 1 (late sowing date). In pot trial, the plants were sown on July 1, grown at natural environment till silking, and suffered two post–silking temperatures (normal temperature and LT were set as 28/20 and 23/15 °C, respectively). The result showed that the starch was composed of more small granules with oval polytope when sown late (August 1) or subjected to LT post–silking. The LT–stressed starch presented high proportion of short amylopectin chains and low relative crystallinity (RC). LT reduced the pasting viscosity, gelatinization enthalpy, and gelatinization temperatures but increased the retrogradation tendency. In conclusion, the low pasting viscosity and high retrogradation tendency under LT condition were caused by the decreased granule size, amylopectin chain length, and RC.

Understanding the changes in particle size, structure, and functional properties of waxy maize starch after jet‐milling treatments

AbstractWaxy maize starch was subjected to fluidized bed jet milling treatments at classifier frequencies of 2,400, 3,000, and 3,600 rpm. Changes in the structure and physicochemical properties of waxy maize starch after jet milling were investigated and compared with the untreated starch. With an increase in classifier frequency, the particle size of starch significantly (p < .05) decreased and showed bimodal distribution after jet milling. The microscopy analysis indicated that surface of starch granules became rough with irregular shapes after jet milling treatment compared to smooth and regular shape for the untreated starch. The birefringence and X‐ray diffraction analyses showed that the jet milling destroyed the crystalline areas and decreased crystallinity of the starch. The micronized starch samples showed significantly lower (p < .05) gelatinization temperature, enthalpy, and viscosity than those of the untreated starch. However, an increase in special surface area, water solubility, swelling power, and pasting stability was found after jet milling of the waxy maize starch. Additionally, light transparency of the starch increased as temperature increased but decreased with storage time. The observed results showed that modified starch can be produced by jet milling.

An insight into the structural evolution of waxy maize starch chains during growth based on nonlinear rheology

This work investigated the chain structure and large amplitude oscillatory shear (LAOS) rheological properties of waxy maize starch (WMS) at different growth periods and established a motion model to clarify the evolution of starch chain structure. During the growth period of 20–25 days, the apparent viscosity and dynamic moduli for WMS paste decreased, along with a greater degree of nonlinearity. This could be correlated with an increasing branching degree of starch due to more short-branched chains generated during growth. With the growth period reaching 25 days, the apparent viscosity, dynamic moduli and zero-strain nonlinearity (Q0) for WMS increased and the b value deviated from 2 significantly, indicating obvious nonlinearity accompanied by a weak stress overshoot and shear-thickening. This could be explained by the growing length of branched chains and the rising content of B3- and B4-chains. Thus, this work demonstrate LAOS rheology can be used as a new and effective method to characterize the chain structural evolution of starch through monitoring the motion pattern of different starch chains under shear conditions.

Insights into the multiscale structure and pasting properties of ball-milled waxy maize and waxy rice starches

The effects of ball-milling on the pasting properties of waxy maize starch (WMS) and waxy rice starch (WRS) were investigated from a multiscale structural view. The results confirmed that ball-milling significantly destroyed the structures of the two waxy starches (especially WMS). Specifically, ball-milling led to obvious grooves on the surface of starch granules, a decrease in crystallinity and the degree of short-range order, and a reduction in double-helix components. Meanwhile, small-angle X-ray scattering results indicated that the semicrystalline lamellae of starch were disrupted after ball-milling. Ball-milling decreased the pasting temperatures. Furthermore, ball-milled starches exhibited lower peak and breakdown viscosity and weakened tendency to retrogradation. These results implied that ball-milling induced structural changes in starch that significantly affected its pasting properties. Hence, ball-milled starch may serve as food ingredients with low pasting temperature and paste viscosity as well as high paste stability under heating/cooling and shearing.

Insights into waxy maize starch degradation by sulfuric acid: Impact on starch structure, pasting, and rheological property

This study investigated the effects of acid degradation of amylopectin on the structure, pasting, and rheological properties of waxy maize starch. It is found that: 1) the amount of amylopectin short-chains with degree of polymerization (DP) ~ 15–50 increased while that of amylopectin long-chains with DP ~ 50–200 decreased by acid hydrolysis; 2) acid hydrolysis produced smaller amylopectin molecules with a narrower size distribution; 3) acid hydrolysis had a minor effect on the crystalline and granular structures of native starch; 4) the pasting viscosity of acid hydrolyzed starch during heating and the consistency coefficient, K, of starch gels increased, whereas the flow behavior index, n, decreased. Correlation analysis was used to clarify the molecular causes for the variations of pasting and rheological properties of acid hydrolyzed starch.

Water and heat stresses during grain formation affect the physicochemical properties of waxy maize starch

Maize is frequently subjected to simultaneous water (drought or waterlogging) and heat (HS) stresses during grain formation in southern China. This work examined the effect of high temperature combined with drought (HD) or waterlogging (HW) during grain formation on the starch physicochemical properties of two waxy maize hybrids, namely Suyunnuo5 (SYN5) and Yunuo7 (YN7). Heat stress enlarged the starch granule size, and water stresses aggravated this effect. Heat stress reduced the ratio of small molecular weight fractions for both hybrids, and HD aggravated this reduction only in SYN5. Relative crystallinity in SYN5 was increased by stresses but in YN7 it was unaffected by HD, reduced by HS, and increased by HW. Fourier-transform infrared (FTIR) spectrometry results showed that the 1045/1022 cm-1 ratio in SYN5 was not influenced by HW but was increased by other stresses, and that in YN7 it was increased by all stresses, with the highest value induced by HW. Peak viscosity was decreased, whereas gelatinization temperatures and retrogradation percentage were increased by all of these stresses. These effects were exacerbated by combined heat and water stresses. The maximum decomposition rate was severely increased by HW. Drought or waterlogging at grain formation stage aggravated the detrimental effects of HS on the starch physicochemical properties of waxy maize. © 2020 Society of Chemical Industry.

Effects of electron beam irradiation on the properties of waxy maize starch and its films

Waxy maize starch was irradiated under different doses of radiation (2–30 kGy), and starch physicochemical properties were analysed. Films were subsequently produced from native and irradiated waxy maize starches and their properties were tested. The starch molecular weight markedly decreased with increasing irradiation dose. And the branch chain length, melting temperature, melting enthalpy, and relative crystallinity decreased slightly, especially at an irradiation dose below 15 kGy. This indicated that more α-1,6-glucosidic bonds than α-1,4-glucosidic bonds were cleaved by a low dose of irradiation; hence, more linear chains were released. Films prepared from 10 kGy irradiated waxy maize starch displayed enhanced mechanical properties and increased solubility, owing to a moderate increase in linear starch chains and a decrease in starch molecular weight, respectively. The resulting rapidly-dissolvable films from irradiated waxy maize starch have potential for use in instant food packaging.

Effects of Nitrogen Rates on the Physicochemical Properties of Waxy Maize Starch

AbstractAppropriate nitrogen fertilization is essential for improving grain yield and starch quality, while reducing N fertilizer costs. The starch physicochemical properties of two waxy maize hybrids, namely, Suyunuo5 (SYN5) and Yunuo7 (YN7), under N rates of 0 (zero N application [N0]), 150 (low N rate [LN]), 225 (moderate N rate [MN]), and 300 (high N rate [HN]) kg ha–1 are elucidated. Grain starch content initially increases, peaks at MN, and decreases as N rate is increased. N fertilization reduces the starch granule size of YN7. The starch granule size of SYN5 increases under MN. SYN5 exhibits high short/long amylopectin chain ratios under LN and MN. The short/long amylopectin chain ratio of YN7 is unaffected by MN but is increases by LN and HN. The swelling power of YN7 is similar among different N levels, whereas that of SYN5 increases under N fertilization. N fertilization changes starch pasting and thermal properties. Starch with large granules exhibit high trough, final, and setback viscosities and gelatinization temperatures. Starch with high long‐chain ratios is susceptible to retrogradation. In conclusion, appropriate N application (225 kg ha–1 for SYN5 and 150 kg ha–1 for YN7) favors starch accumulation, and starch has high viscosity and low retrogradation tendency.

Effects of short‐term heat stress at the grain formation stage on physicochemical properties of waxy maize starch

Waxy maize (Zea mays L. sinensis Kulesh) suffers short-term exposure to high temperature during grain filling in southern China. The effects of such exposure are poorly understood. Starch granule size was increased by 5 days' short-term heat stress (35.0 °C) and the increase was higher when the stress was introduced early. Heat stress increased the iodine binding capacity of starches and no difference was observed among the three stages. Starch relative crystallinity was increased and swelling power was decreased only when heat stress was introduced early. Heat stress also increased the pasting viscosity, and this effect became more pronounced with later applications of stress. Heat stress reduced starch gelatinization enthalpy, and the reduction gradually increased with later exposures. Heat stress increased the gelatinization temperature and retrogradation enthalpy and percentage of the samples, with the increases being largest with earlier introduction of high temperature. Heat stress increased the pasting viscosities and retrogradation percentage of starch by causing change in granule size, amylopectin chain length distribution and crystallinity, and the effects observed were more severe with earlier introduction of heat stress after pollination. © 2017 Society of Chemical Industry.

Effect of microwave irradiation on internal molecular structure and physical properties of waxy maize starch

Native waxy maize starch was treated at a moisture content of 30% by microwave irradiation for 5 min, 10 min and 20 min, respectively. The molecular structure and physical properties of waxy maize starch were characterized. Compared with native maize starch, lower population of short chains of amylopectin (A chain), higher proportion of short B1 and long B2 and B3 were observed in irradiated starches. 1H NMR data showed that α-(1,6) glycosidic linkages were destroyed more easily than α-(1,4) glycosidic linkages during microwave treatment. A increase in gelatinization temperatures and a decrease in the molecular weight, the relative crystallinity, ΔH, viscosities and syneresis were observed after microwave treatment. Gelatinization temperatures were positively correlated with long chains B3 with DP > 36, while ΔH and syneresis were negatively correlated with them. The extent of the changes induced by microwave treatment for different times revealed that the major degradation occurred in internal chain (amorphous region) at the first stage (microwave treatment for 5 min), the external chain (crystalline region) mostly destroyed at the second stage (microwave treatment for above 10 min). The foregoing data indicated that the molecular structure of amylopectin is a critical factor determining physical properties.

Effects of high temperature during grain filling on physicochemical properties of waxy maize starch

AbstractUnderstanding the waxy maize starch physicochemical properties response to heat stress during grain filling could improve starch quality. The effects of heat stress during early (1–15 days after pollination, DAP) and late (16–30 DAP) grain filling stages on the starch physicochemical properties of four waxy maize varieties were evaluated. Crystallinity only increased in Suyunuo 5 after exposure to high temperature at late grain filling stage. The effects of heat stress on digestibility and swelling power were dependent on varieties and stages. Generally, swelling power was increased by heat stress at early grain development stage and digestibility was increased by high temperature at late grain filling stage, respectively. The results of correlation analysis indicated the starch with large granule size could swell well and easy digest. Peak, trough, final, and breakdown viscosities in response to heat stress were dependent on stages and varieties. In general, peak, trough and final viscosities were decreased and increased by heat stress at early grain formation and late grain filling stages, respectively; whereas the breakdown and setback viscosities were similar among the three treatments. Heat stress increased the gelatinization temperatures and retrogradation percentage. Gelatinization range decreased under heat stress at 1–15 DAP but remained constant under heat stress at 16–30 DAP in all varieties. The starch exposed to high temperature at 16–30 DAP presented higher digestibility and peak viscosity and lower retrogradation percentage than those at 1–15 DAP. Therefore, heat stress at early grain formation stage severely affects the physicochemical properties of starch.

Effects of water deficit during grain filling on the physicochemical properties of waxy maize starch

The effects of water deficit after pollination on the physicochemical properties of waxy maize starch were clarified, using Suyunuo5 and Yunuo7 as test materials. Pot experiments were conducted in 2012 and 2013; a pool trial was performed in 2014. Results indicated that the starch granule size was decreased by water deficit in both pot and pool experiments. Furthermore, the water deficit reduced the starch crystallinity and peak intensities at different reflection angles. The reduced iodine binding capacity under drought condition indicated that the proportion of long chains in amylopectin was decreased by water deficit. Swelling power was only decreased by drought under pool condition. The structural changes in starch decreased the peak and breakdown viscosities, but increased the retrogradation percentage. The maximum absorption wavelength, blue value, gelatinization enthalpy, pasting and gelatinization temperatures of starch were not affected by the water deficit. Therefore, drought during grain filling deteriorated the pasting viscosities and increased the tendency of retrogradation by reducing the starch granule size, proportion of long-chains in amylopectin, swelling power, and crystallinity.

Effects of heat stress during grain filling on the structure and thermal properties of waxy maize starch

Clarifying the waxy maize starch physicochemical characteristics response to heat stress could modify starch quality. The effects of heat stress during grain filling (1–40day after pollination) on starch structure and thermal properties of four waxy maize varieties were investigated. The mean day/night temperature during grain filling for heat stress and control treatments was 35.2/16.1°C and 27.4/15.6°C, respectively. Heat stress during grain filling increased the starch average granule size and the proportion of long chains in amylopectin. Starch granules under heat stress presented more pitting or uneven surfaces. X-ray peak intensities in response to heat stress were variety dependent. Heat stress during grain filling decreased the swelling power and increased the gelatinization temperature and retrogradation percentage, while the gelatinization enthalpy was not affected. In conclusion, heat stress during grain filling significantly affected structural characteristics of waxy maize starch and consequently, changed its swelling and thermal properties.

Impact of mild acid hydrolysis on structure and digestion properties of waxy maize starch

In this study, the molecular structure of acid-treated waxy maize starch residues was investigated, and the in vitro digestibility of the residues with 2.2N HCl at 35°C for different time periods, was assessed. The granular appearance of waxy maize starch was destroyed and small fractions formed aggregates. A change in chain-length distribution profiles occurred with the degradation of shortest A chains and long B chains in amylopectin. The rise in the ratio of absorbance height at 1047cm−1 to the height at 1022cm−1, the intensities of major peaks, Xc, Tp, Tc, and ΔH were observed during mild acid hydrolysis, but the X-ray diffraction patterns displayed A-type for all starches. The amount of rapidly digestible starch increased, whereas the amounts of slowly digestible and resistant starch decreased. These results demonstrate that the amorphous regions of starch granules, including the shortest A chains and long B chains, are preferentially hydrolysed and affect the slow digestion and resistance properties of waxy maize starch.

Thermal and rheological properties of granular waxy maize mutant starches after isoamylase modification

This work investigated the changes in the thermal and rheological property of two waxy maize mutant starches (Hsyn73 wxwx and Hsyn73 duwx) after they were treated with isoamylase in the granular state for various periods. The hydrolysis degrees reached in 168 h were 4.0% and 9.5% for the wxwx and the duwx, respectively. With increasing degree of hydrolysis, both wxwx and duwx generally showed an increase in gelatinization and retrogradation temperatures and retrogradation enthalpy. The weight average molar mass ( M w), z-averaged radius of gyration ( R z ), and pasting viscosity of both starches decreased when isoamylase hydrolysis progressed, however, the wxwx showed a greater decrease in M w and R z than the duwx at the same hydrolysis degree. Both wxwx and duwx, native or isoamylase-treated, displayed a similar pasting viscosity during holding and cooling when their amylopectin molecules had a similar R z . The study indicates the importance of R z in determining the pasting properties of waxy maize starch.

Thermal and rheological properties of granular waxy maize mutant starches after β-amylase modification

The objective of this work was to investigate the impact of β-amylolysis on the physicochemical properties of two granular waxy maize mutant starches. The β-amylolysis progressed rapidly at the beginning and then gradually leveled at approximately 5% for wxwx and 8.5% for duwx. With increasing β-amylolysis, both starches showed a decrease in the proportion of long B chains, average chain length, molar mass, and z-averaged radius of gyration, but an increase in the proportion of short B and A chains, and chains with 2–5 glucose units. The onset gelatinization temperature and pasting viscosity of hydrolyzed samples did not decrease until reaching the hydrolysis degree of 5% for the wxwx and 8.5% for the duwx. Moreover, both wxwx and duwx retained their respective characteristics in molecular size distribution and rheological properties during β-amylolysis. The rheological properties of waxy maize starch were more affected by the crystalline structure and the proportion of long chains in amylopectin.

Starch Gelatinization and Retrogradation Properties under Different Basic Fertilizer Regimes and Nitrogen Topdressing at Jointing Stage of Waxy Maize

Proper fertilizer managements can improve the starch gelatinization and retrogradation properties of waxy maize(Zea mays L.Ceratina Kulesh).The split-design experiment was conducted using waxy maize cultivar Suyunuo 4 with four main plots subjected to basal fertilizer treatments of N 75 kg ha-1,N 75 kg ha-1+K2O 70 kg ha-1,N 75 kg ha-1+P2O5 65 kg ha-1,and N 75 kg ha-1+P2O5 65 kg ha-1+K2O 70 kg ha-1,respectively in 2007 and 2008.The three split plots were topdressed with nitrogen of 0,150,and 300 kg ha-1 at jointing stage,respectively.Though onset temperature(To),peak temperature(Tp) and conclusion temperature(Tc) of native starch and retrogradated starch were affected by fertilizer treatments,the variation was little.No significant effects were observed for basic fertilizer treatments on the enthalpy of gelatinization(ΔHgel),and for N topdressing treatments on gelatinization range(R) and peak height index(PHI).The R-value was the lowest in the treatment with only N and K in basal fertilizer,and the highest in the treatment with N,P,and K in basal fertilizer.The changes of PHI showed an opposite trend to R.The ΔHgel was the highest in the treatment with medium N topdressing(150 kg ha-1).Gelatinized starch became retrograded with lower To,Tp,Tc,enthalpy of retrogradation(ΔHret),and PHI,as well as wider R.Compared with the treatment of only N applied in basal fertilizer,the percentage of retrogradation and ΔHret decreased when P and/or K added in the basal fertilizer.The two indicators were higher in the treatments with N topdressing than without N topdressing.The percentage of retrogradation was posi-tively correlated with ΔHret(r = 0.90,P 0.01) and PHI of retrograded starch(r = 0.41,P 0.05).ΔHgel was positively correlated with PHI(r = 0.65,P 0.01) and ΔHret(r = 0.44,P 0.05),but negatively correlated with Tc(r =-0.41,P 0.05).It is recommended to apply balanced fertilization with N,P,and K combining with moderate N topdressing under conditions similar to the experiment to improve gelatinization and retrogradation properties of waxy maize starch.

Rheological properties of waxy maize starch and xanthan gum mixtures in the presence of sucrose

Rheological properties of 5% (w/w) waxy maize starch (WMS)/xanthan gum (XG) mixed pastes (mixing ratios: 10/0, 9.5/0.5, 9/1) in the presence of sucrose (0%, 15%, and 30%) were studied. The 5% WMS paste displayed strong anti-thixotropic behavior based on the heating method adopted (heating in water bath for 40 min with mixing at 200 rpm). The addition of XG could accelerate the formation of new structure of the WMS/XG mixed pastes under shear conditions, and XG could also decrease the in-shear recoveries of the mixtures. Both the addition of XG and sucrose increased the apparent viscosity ( η a) and dynamic moduli ( G′ and G″) of the mixed pastes, with XG contributing to the solid-like properties of the mixtures obviously, while sucrose played a contrary role. Thermostable properties of the mixed pastes could be improved distinctly with the addition of XG, whereas sucrose decreased it slightly.

Influence of reaction conditions on MS values and physical properties of waxy maize starch derivatized by reaction with propylene oxide

Waxy maize starch was hydroxypropylated under different swelling conditions (pH, temperature, salt type, salt concentration) to determine the effect of reaction conditions on the extent of modification. MS, pasting temperatures, and paste characteristics of the products were determined. pH had the greatest effect on the extent of reaction. MS values increased as the pH was raised from 10.7 to 11.7. In most cases, samples hydroxypropylated in the presence of NaCl had lower or equal MS values as compared to those reacted in the presence of Na 2SO 4, and reactions carried out in the presence of NaCl were more sensitive to changes in pH than were those conducted in the presence of Na 2SO 4. The lower MS values for samples reacted in the presence of NaCl was most notable at the lowest pH value. Temperature had less effect on reaction efficiency. No substantial differences were found in pasting temperature or peak viscosity. Under conditions that promoted greatest swelling, viz. highest pH (11.7) and highest temperature used (54 °C), some granules reacted in the presence of NaCl gelatinized, i.e. NaCl failed to prevent pasting. Therefore, it was confirmed that Na 2SO 4 better protects against gelatinization than does NaCl. The concentration of Na 2SO 4 (0.395 vs. 0.527 m) only slightly affected MS values.