Hylon VII Starch Research Articles

Effect of drying method and hydrothermal treatment of pregelatinized Hylon VII starch on resistant starch content

The effect of pregelatinization and drying method in resistant starch (RS) content of high amylose starch (Hylon VII, 70% amylose content) was studied. Starch was subjected to autoclaving pre-gelatinization (40% starch suspension w/w, 121 °C) for 30 min. Oven-drying (OD) at 40 °C for 24 h and freezing-drying (FD) methods were used. Subsequently, hydrothermal treatment (HT) with 40% water content at 100 °C for 3, 12 and 24 h was applied to dried samples. Pre-gelatinization decreased the RS content by about 25% with respect to the Hylon VII starch. The drying method affected the RS content, with OD increasing and FD decreasing the RS content. HT time affected positively the RS content for OD starch, whilst the opposite effect was obtained for FD starch. XRD analysis revealed that B-type crystallinity of native starch was modified by drying and HT. Weak linear correlation (R2 = 0.69) between RS content and relative crystallinity was found. However, strong exponential correlation (R2 = 0.96) between RS content and short-range ordering quantified by FTIR measurements were found. This suggests that RS is close related to formation of double-helix and amylose-lipid complex (evidenced by the XRD peak at 2θ = 20°) during drying and heat treatment of starch.

Effect of phosphorylation and pretreatment with high hydrostatic pressure on radical processes in maize starches with different amylose contents

Waxy maize (amylopectin with trace amounts of amylose) and Hylon VII starch containing mostly amylose were phosphorylated in acidic or alkaline medium to produce mono- or distarch phosphates, respectively. The changes in the starch structure and properties occurring upon phosphorylation and high pressure treatment (650 MPa/9 min) were analyzed using X-ray diffraction (XRD), differential scanning calorimetry (DSC), polarized light microscopy (LM) and electron paramagnetic resonance (EPR) spectroscopy. Quantitative EPR measurements revealed that incorporation of phosphorus into the starch structure increased tendency of the starch to be thermally degraded with formation of radicals, the effect being more pronounced in the case of monostarch phosphates than in distarch phosphates. Pretreatment of the starch with high hydrostatic pressure resulted in diminishing of the number of radicals generated thermally in monostarch phosphates.

Kinetics of hydrolysis and changes in amylose content during preparation of microcrystalline starch from high-amylose maize starches

Two commercial sources of high amylose (∼65% amylose) maize starch, Hi-maize and Hylon VII, were acid-hydrolyzed to produce microcrystalline starch and hydrolyzed starch sugar solution. The yield of microcrystalline starch was lower than 50% of the original starch weight when hydrolysis was carried for up to 8 days. The kinetics of hydrolysis was divided into three stages. The slope of the linear graph ranged from 11.11 to 11.36 mg/(ml days), 4.24 to 4.55 mg/(ml days), and 2.15 to 3.96 mg/(ml days) in the first, second and third stage and corresponded to a rapid, slow and very slow hydrolysis rates, respectively. HPAEC-ED analyses of the hydrolyzed starch solutions revealed 14 and four major sugar and oligosaccharide components when the hydrolysis was carried for 1 and 8 days, respectively. There was a good linear relationship between glucose content and hydrolysis time ( R > 0.992). Oligosaccharide components (dp ⩾ 2) attained highest levels and then decreased with further increase in hydrolysis time. For hydrolyzed Hi-maize starch solution, the highest levels were 35.9, 12.4, 8.3, 7.6, 2.8, 2.3, and 2.0 mg/ml for glucose (dp 1), maltose (dp 2), maltotriose (dp 3), maltotetraose (dp 4), maltopentaose (dp 5), maltohexaose (dp 6), and maltoheptaose (dp 7), respectively. Similarly, hydrolyzed Hylon VII starch solution contained the highest levels at 31.8, 12.7, 7.2, 5.6, 4.3, 2.7, and 2.2 mg/ml for glucose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, and maltoheptaose, respectively. The critical times (rapid to slow transition) for hydrolysis of Hylon VII and Hi-maize starches should be between 5 and 6 days under the present conditions for preparation of microcrystalline starch. The hydrolysis process also significantly increased amylose content of microcrystalline starch.

Development and Physicochemical Characterization of New Resistant Citrate Starch from Different Corn Starches

AbstractResistant starch has drawn broad interest for both potential health benefits and functional properties. In this study, a technology was developed to increase resistant starch content of corn starch using esterification with citric acid at elevated temperature. Waxy corn, normal corn and high‐amylose corn starches were used as model starches. Citric acid (40% of starch dry weight) was reacted with corn starch at different temperatures (120–150°C) for different reaction times (3–9 h). The effect of reaction conditions on resistant starch content in the citrate corn starch was investigated. When conducting the reaction at 140°C for 7 h, the highest resistant starch content was found in waxy corn citrate starch (87.5%) with the highest degree of substitution (DS, 0.16) of all starches. High‐amylose corn starch had 86.4% resistant starch content and 0.14 DS, and normal corn starch had 78.8% resistant starch and 0.12 DS. The physicochemical properties of these citrate starches were characterized using various analytical techniques. In the presence of excess water upon heating, citrate starch made from waxy corn starch had no peak in the DSC thermogram, and small peaks were found for normal corn starch (0.4 J/g) and Hylon VII starch (3.0 J/g) in the thermograms. This indicates that citrate substitution changes granule properties. There are no retrogradation peaks in the thermograms when starch was reheated after 2 weeks storage at 5°C. All the citrate starches showed no peaks in RVA pasting curves, indicating citrate substitution changes the pasting properties of corn starch as well. Moreover, citrate starch from waxy corn is more thermally stable than the other citrate starches.

Molecular Structure of a Low-Amylopectin Starch and Other High-Amylose Maize Starches

The molecular structure of two commercially available high-amylose maize starches, HYLON® V starch and HYLON® VII starch, and of a newly developed low-amylopectin starch (LAPS) was examined. These high-amylose starches give three apparent fractions as determined by gel-permeation chromatography: a high-molecular weight (mol.wt) amylopectin fraction, a low-mol.wt amylose fraction, and an intermediate-mol.wt fraction which contains both linear and branched components. The low-mol.wt amylose fraction increases from 9·4% in HYLON V starch to 17·7% in HYLON VII starch and 26·5% in LAPS, whereas the high-mol.wt amylopectin fraction decreases from 31·1% in HYLON V starch to 13·8% in HYLON VII starch and 2·5% in LAPS. The percentage of linear components in HYLON V starch, HYLON VII starch, and LAPS are 42, 54, and 80%, respectively. High-amylose starches have a large proportion of long chains in their branched fractions compared to waxy-maize and normal-maize starch. Both HYLON VII starch and the LAPS give B plus V-type X-ray diffraction patterns, but the LAPS has even a higher gelatinization temperature, lower swelling power in hot water, and is more resistant to acid digestion. With the lack of amylopectin, amylose accounts for at least part of the double helical structure in the LAPS granules.