Ya-jane Wang

ABSTRACT The morphology and tensile properties of low density polyethylene (LDPE) and starch blends were analyzed. The effect of granular size and shape on these properties was examined. The analysis showed that the properties of composites from the same starch were more affected by granule size while the properties of composites from different starches were more influenced by granule intrinsic properties.

ABSTRACT This work was undertaken to investigate the effects of amylose content and chemical modification on enzyme resistant dextrin content of high amylose corn mutant dextrins. Dextrins made from high amylose corn mutant starches, including dull sugary 2 (du su2), amylomaize V, amylose extender dull (ae du), amylomaize VII, and chemically modified amylomaize V and VII, were characterized for moisture, solubility, reducing sugars, and enzyme resistant dextrin contents after dextrinization. Moisture content decreased, whereas soluble and reducing sugar contents rose rapidly in the first 60 min of conversion. Reducing sugar content began to decrease after 60 min of reaction, which corresponded to the onset of a rapid increase in enzyme resistant dextrin content. The enzyme resistant component in dextrin was not detected until fragments of low molecular-weight saccharides were produced by hydrolysis. These fragments recombined into randomly branched molecules that were resistant to enzymatic digestion. One proposed mechanism contributing to the lower enzyme resistant dextrin content of chemically modified high amylose corn dextrins is that the introduction of modifying groups to starch presented a steric hindrance for transglucosidation and repolymerization reactions during dextrinization, consequently resulting in lower enzyme resistant dextrin content.

Abstract Starch isolated from unripe bananas was oxidized under different conditions and the physicochemical properties of the oxidized banana starches were characterized. It was found that pH was the dominating factor in the formation of carboxyl groups. Higher yields ...

... Authors Giannoccaro and Wang are with Dept. of Food Science, Univ. of Arkansas, Fayetteville, AR 72704. Author Chen is with Dept. of Crop, Soil and Environ-mental Sciences, Univ. of Arkansas, Fayetteville, Ark. Direct inquiries to author Wang (E-mail: yjwang@uark.edu). ...

This study examined the compositional change of five specialty soybean genotypes, which are low in oligosaccharides, high in oil, high in protein, large seeded or small seeded, along with two commercial cultivars, Jack and Ozark, during seed development and maturation. Seeds were sampled at 7-day intervals from initial seed formation to full maturity for approximately 8weeks, and analysed for oil,

Eight commercial starches, including common corn, waxy corn, wheat, tapioca, potato, Hylon V, Hylon VII, and mung bean starch, were annealed by a multiple-step process, and their gelatinization characteristics were determined. Annealed starches had higher gelatinization temperatures, reduced gelatinization ranges, and increased gelatinization enthalpies than their native starches. The annealed starches with the highest gelatinization enthalpies were subjected to acid hydrolysis with 15.3% H2SO4, and Naegeli dextrins were prepared after 10 days' hydrolysis. Annealing increased the acid susceptibility of native starches in the first (rapid) and the second (slow) phases with potato starch showing the greatest and high amylose starches showing the least changes. Starches with a larger shift in onset gelatinization temperature also displayed a greater percent hydrolysis. The increase in susceptibility to acid hydrolysis was proposed to result from defective and porous structures that resulted after annealing. Although annealing perfected the crystalline structure, it also produced void space, which led to porous structures and possible starch granule defects. The molecular size distribution and chain length distribution of Naegeli dextrins of annealed and native starches were analyzed. The reorganization of the starch molecule during annealing occurred mainly within the crystalline lamellae. Imperfect double helices in the crystalline lamellae improved after annealing, and the branch linkages at the imperfect double helices became protected by the improved crystalline structure. Therefore, more long chains were observed in the Naegeli dextrins of annealed starches than in native starches.

The effects of annealing on the complexing of added palmitic acid (PA) and on the physicochemical properties of starch were studied. Palmitic acid was used because of its predominance in starch lipids. Starches naturally low in lipids, including potato, tapioca, and waxy corn, were subjected to the PA treatment. Common corn starch, which is high in lipids, was also included

... 2005] and [Seker and Hanna, 2005]) have been done to elucidate the effect of various extrusion parameters on the actual phosphorylation of starch and whether these trends differ with the oven-heating method. A recent study (O'Brien, Wang, Vervaet, & Remon, 2008) prepared ...