Jinglin Yu

Effect of fatty acids on functional properties of normal wheat and waxy wheat starches: A structural basis.

The effects of three saturated fatty acids on functional properties of normal wheat and waxy wheat starches were investigated. The complexing index (CI) of normal wheat starch-fatty acid complexes decreased with increasing carbon chain length. In contrast, waxy wheat starch-fatty acid complexes presented much lower CI. V-type crystalline polymorphs were formed between normal wheat starch and three fatty acids, with shorter chain fatty acids producing more crystalline structure. FTIR and Raman spectroscopy presented the similar results with XRD. The formation of amylose-fatty acid complex inhibited granule swelling, gelatinization progression, retrogradation and pasting development of normal wheat starch, with longer chain fatty acids showing greater inhibition. Amylopectin can also form complexes with fatty acids, but the amount of complex was too little to be detected by XRD, FTIR, Raman and DSC. As a consequence, small changes were observed in the functional properties of waxy wheat starch with the addition of fatty acids.

A comparative study of annealing of waxy, normal and high-amylose maize starches: The role of amylose molecules

The effect of annealing on starch structure and functionality of three maize starches (waxy, normal and high-amylose) was investigated, with the aim of understanding the role of amylose molecules during starch annealing. Amylose content, granular morphology and crystallinity of maize starches were little affected by annealing treatment. Annealing treatment did not alter the swelling power of waxy maize starch, but reduced the swelling power of normal and high-amylose maize starches. The thermal transition temperatures were increased, and the temperature range was decreased, but the enthalpy change was not affected greatly. The pasting viscosities of normal and waxy maize starches were decreased significantly, with the pasting temperature being little affected. The in vitro digestibility of three maize starches was not affected significantly by annealing treatment. Our results demonstrated that amylose molecules play an important role in the structural reorganization of starch granules during annealing treatment.

Molecular order and functional properties of starches from three waxy wheat varieties grown in China

Molecular order and functional properties of starch from three waxy wheat varieties grown in China were investigated by a combination of various technical analyses. The total starch content of the waxy wheat ranged between 54.1% and 55.0%, and the amylose content of the starch was between 0.71% and 1.63%. Average particle diameter of the three starches varied between 16.5 and 17.4 μm. Three waxy wheat starches presented the typical A-type X-ray diffraction pattern, with relative crystallinity between 38.7% and 40.0%. No significant differences were observed in relative crystallinity, IR ratios of 1047/1022 cm(-1) and 1022/995 cm(-1), and FWHH of the band at 480 cm(-1), indicating the similarity in long-range order of crystallites and short-range order of double helices of three starch granules. Small differences were observed in swelling power, gelatinization parameters, pasting viscosities, and in vitro enzymatic digestibility of three waxy wheat starches. Under the stored condition, no retrogradation occurred for three waxy wheat starches.

Effect of laboratory milling on properties of starches isolated from different flour millstreams of hard and soft wheat

The properties of starch from different flour millstreams are very important for the production of specific flours used in different wheat-based food products. The present study aimed at characterising starches from different flour millstreams by Buhler laboratory mill and flour from Brabender senior mill. Damaged starch content increased from 3.4% to 15.7% and from 1.8% to 6.0% for flour from B1 to R3 millstream of Beijing 0045 and Zhongmai 175, respectively. Milling resulted in the fragmentation of starch granules, but did not induce significant changes in the relative crystallinity. Starches from different flour millstreams presented similar swelling power values. Except onset temperature of starches from Beijing 0045, no significant differences were observed in thermal transition parameters of starches from Beijing 0045 or Zhongmai 175. Pasting and in vitro digestion profiles of starches from different flour millstreams showed significant differences. This study showed that laboratory milling induces variable differences in functional properties without changing starch crystalline structure.

Insights into the formation and structures of starch-protein-lipid complexes.

The aim of the present study was to characterize the multiscale structures of ternary complexes of a model system of starch, fatty acid (FA), and β-lactoglobulin (βLG) prepared using a Rapid Visco Analyzer (RVA). The addition of βLG to starch-lauric acid or starch-oleic acid RVA pastes resulted in the increased intensity or occurrence of a new viscosity peak during cooling when the RVA protocol was repeated. The viscosity peak was attributed to the formation of starch-βLG-FA complexes. Differential scanning calorimetry (DSC) results showed clearly that the starch-βLG-FAs complex was formed as gelatinized starch was cooled in the presence of βLG and FAs. The results of Raman, FTIR, and X-ray diffraction analyses showed that starch can interact with βLG and FAs to form a ternary V-type crystalline complex, which had a greater short-range molecular order and higher relative crystallinity compared with those of the binary starch-FA complex. The present study provided insights into the structure of a model starch-protein-fatty acid complex as an example of what might occur during food processing.

Multi-scale structures and functional properties of starches from Indica hybrid, Japonica and waxy rice

The structural and functional properties of starches from three rice grains differing in amylose content (19.9, 13.4 and 0.8% for Japonica, Indica hybrid and waxy rice, respectively) were investigated using a range of characterization methods Indica hybrid starch (IHS) had the highest proportion of intermediate (DP 13-24) and long branch chains (DP≥37) and the lowest proportion of short branch chains (DP 6-12), whereas the opposite results were observed for Japonica starch (JS). The results for waxy rice starch (WS) were between those of IHS and JS. Rice starches showed a typical A-type X-ray diffraction pattern with the relative crystallinity ranging from 33.4% for JS to 39.4% for WS. Significant differences were observed in lamellar distance and short-range molecular order characterized by IR ratio of absorbances at 1047/1022cm-1 and full width of half maximum (FWHM) of the band at 480cm-1. WS showed a higher swelling power and a lower close packing concentration at temperatures from 60 to 90°C. The lower peak viscosity of WS was attributed to the formation of less rigid swollen granules at a concentrated regime. WS showed a higher in vitro digestibility compared with IHS and JS.

Mechanisms Underlying the Formation of Complexes between Maize Starch and Lipids

This study aimed to reveal the mechanism of formation of complexes between native maize starch (NMS) and different types of lipids, namely palmitic acid (PA), monopalmitate glycerol (MPG), dipalmitate glycerol (DPG), and tripalmitate glycerol (TPG). The complexing index followed the order of MPG (96.3%) > PA (41.8%) > TPG (8.3%) > DPG (1.1%), indicating that MPG formed more complexes with NMS than PA, and that few complexes were formed between NMS and DPG and TPG. The NMS-PA complex presented higher thermal transition temperatures and lower enthalpy change than the NMS-MPG complex, indicating that although MPG formed more starch complexes, they had less stable crystalline structures than the complex between NMS and PA. X-ray diffraction (XRD) and Raman spectroscopy showed that both MPG and PA formed V-type crystalline structures with NMS, and confirmed that no complexes were formed between NMS and DPG and TPG. We conclude that the monoglyceride formed more starch-lipid complex with maize starch than PA, but that the monoglyceride complex had a less stable structure than that formed with PA. The di- and triglycerides did not form complexes with maize starch.

Starch Spherulites Prepared by a Combination of Enzymatic and Acid Hydrolysis of Normal Corn Starch

This paper describes a new method to prepare spherulites from normal corn starch by a combination of enzymatic (mixtures of α-amylase and amyloglucosidase) and acid hydrolysis followed by recrystallization of the hydrolyzed products. The resulting spherulites contained a higher proportion of chains with a degree of polymerization (DP) of 6-12 and a lower proportion of chains with DP of 25-36, compared to those of native starch. The spherulites had an even particle size of about 2 μm and a typical B-type crystallinity. The amounts of long- and short-range molecular order of double helices in starch spherulites were larger, but the quality of starch crystallites was poorer, compared to that of native starch. This study showed an efficient method for preparing starch spherulites with uniform granule morphology and small particle size from normal corn starch. The ratios of α-amylase and amyloglucosidase in enzymatic hydrolysis had little effect on the structure of the starch spherulites.

Effects of chain length and degree of unsaturation of fatty acids on structure and in vitro digestibility of starch-protein-fatty acid complexes

The effects of chain length and degree of unsaturation of fatty acids (FAs) on structure and in vitro digestibility of starch-protein-FA complexes were investigated in model systems. Studies with the rapid visco analyzer (RVA) showed that the formation of ternary complex resulted in higher viscosities than those of binary complex during the cooling and holding stages. The results of differential scanning calorimetry (DSC), Raman, and X-ray diffraction (XRD) showed that the structural differences for ternary complexes were much less than those for binary complexes. Starch-protein-FA complexes presented lower in vitro enzymatic digestibility compared with starch-FAs complexes. We conclude that shorter chain and lower unsaturation FAs favor the formation of ternary complexes but decrease the thermal stability of these complexes. FAs had a smaller effect on the ordered structures of ternary complexes than on those of binary complexes and little effect on enzymatic digestibility of both binary and ternary complexes.

Effect of dual modification by annealing and ultrahigh pressure on properties of starches with different polymorphs

The effects of dual modification by annealing (ANN) and ultrahigh pressure (UHP) on properties of wheat, yam, and potato starches were investigated. Compared with the single UHP treatment (400MPa), ANN-UHP (400MPa) treatment did not alter significantly the ordered structures of wheat starch, indicating that ANN treatment enhanced the stability and resistance of starch granules to the subsequent UHP treatment. In contrast, UHP (400MPa)-ANN treatment resulted in more severe disruption of ordered structures of wheat starch than did the single UHP treatment, showing that UHP-treated starch was more vulnerable to the subsequent ANN treatment. The dual modifications had little effect on granular structures of yam and potato starches. ANN-UHP (300 and 400MPa) and UHP (300MPa)-ANN treatments enhanced greatly the pasting viscosities of UHP-modified starches. Dual modifications altered greatly the pasting properties of yam and potato starches, as observed for the single ANN treatment. From this study, we proposed that ANN treatment enhanced stability of wheat starch by increasing interaction of starch chains in amorphous regions.