Beatriz Millan-Malo

Analysis of thermal pasting profile in corn starch rich in amylose and amylopectin: Physicochemical transformations, part II.

This work focused on the study of the behaviors of the apparent viscosity profiles of isolated corn starches rich in amylose and amylopectin, through the physicochemical and morphological changes that take place during the thermal profile and the gel formation. Frozen dry samples were studied at different stages along the pasting profile. Changes in the structural properties of the samples were studied using X-ray diffraction, and the morphological changes were followed using scanning electron microscopy, differential scanning calorimetry was used to analyze the thermal changes. The changes in the pasting profile (curve of apparent viscosity) were associated with structural, thermal, and morphological changes of the starch-water suspension. From the results obtained, a new interpretation of the parameters measured with the pasting profile is introduced. In this work does not show evidence of retrogradation at the end of the cooling process for starch rich in amylopectin and that starch rich in amylose does not develop viscosity.

Cooling rate effects on thermal, structural, and microstructural properties of bio-hydroxyapatite obtained from bovine bone

This article is focused on the study of cooling rate effects on the thermal, structural, and microstructural properties of hydroxyapatite (HAp) obtained from bovine bone. A three-step process was used to obtain BIO-HAp: hydrothermal, calcinations, and cooling. Calcined samples in a furnace and cooling in air (HAp-CAir), water (HAp-CW), and liquid nitrogen (HAp-CN2), as well as an air cooled sample inside the furnace (HAp-CFAir), were studied. According to this study, the low cooling rate that was achieved for air cooled samples inside the furnace produce single crystal BIO-HAp with better crystalline quality; other samples exhibited polycrystalline structures forming micron and submicron grains.

Morphological, structural, thermal, compositional, vibrational, and pasting characterization of white, yellow, and purple Arracacha Lego-like starches and flours ( Arracacia xanthorrhiza )

This work is focused on the chemical, structural, morphological, thermal, IR vibrational, and pasting characterization of isolated white, yellow, and purple Arracacha starches from Colombia. Inductive couple plasma showed that these starches are rich in potassium. Scanning Electron Microscopy (SEM) images show that the starch granules are formed by ovoid fully filled Lego-like starch microparticles, the circular cross-section has a diameter between 9 and 15μm and mayor axis between 20 and 30μm. Each one of these ovoids is formed by irregular wedge-shaped 6 to 10 isolated starch granules with an average size between 4 and 12μm. The amylose content ranged between 31 and 36%. Arracacha starches exhibited high viscosity values (between 20.000 and 28.000cP), which could be influenced by the high content of potassium ions, due to the C-H~K Van Der Waals interaction that was identified by using IR spectroscopy. According to the X-ray diffraction analysis, the starch patterns exhibited broad diffracted peaks which could be associated with the existence of nano-crystals and lamellae; the Differential Scanning calorimetry (DSC) result showed starches with a low gelatinization temperature of about 60°C.