Monitoring the crystallization of amylose–lipid complexes during maize starch melting by synchrotron x‐ray diffraction

Most starch granules exhibit a natural crystallinity, with different diffraction patterns according to their botanical origin: A‐type from cereals and B‐type from tubers. The V polymorph results essentially from the complexing of amylose with compounds such as iodine, alcohols, or lipids. The intensity and nature of phase transitions (annealing, melting, polymorphic transitions, recrystallization, etc.) induced by hydrothermal treatments in crystalline structures are related to temperature and water content. Despite its small concentration, the lipid phase present mainly in cereal starches has a large influence on starch properties, particularly in complexing amylose. The formation of Vh crystalline structures was observed by synchrotron x‐ray diffraction in native maize starch heated at intermediate and high moisture contents (between 19 and 80%). For the first time, the crystallization of amylose–lipid complexes was evidenced in situ by x‐ray diffraction without any preliminary cooling, at heating rates corresponding to the usual conditions for differential scanning calorimetry experiments. For higher water contents, the crystallization of Vh complexes clearly occurred at 110–115°C. For intermediate water contents, mixed A + Vh (or B + Vh for high amylose starch) diffraction diagrams were recorded. Two mechanisms can be involved in amylose complexing: the first relating to crystallization of the amylose and lipid released during starch gelatinization, and the second to crystalline packing of separate complexed amylose chains (amorphous complexes) present in native cereal starches. © 1999 John Wiley & Sons, Inc. Biopoly 50: 99–110, 1999     

Glass transition temperatures and water sorption isotherms of cassava starch

The effect of water content on the glass transition temperatures of cassava starch was determined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Samples were transformed to the amorphous state by compression molding at high temperature (as demonstrated by wide angle X-ray diffraction, WAXS), and then the samples were moisture conditioned. Both DSC and DMTA showed that water anti-plasticized cassava starch at lower moisture contents, and plasticized it at higher water contents. Samples with higher moisture contents stored at room temperature, 45 °C and 80 °C underwent retrogradation as indicated by WAXS. Sorption isotherms of cassava starch showed that for a_w values lower than around 0.85, the sorption capacity decreased with increasing temperature; while the opposite behavior was observed at a_w > 0.85. This inversion point (a_w = 0.85) was attributed to the fact that more active sites were exposed to the adsorption processes, due to the enhanced molecular mobility promoted in the amorphous regions by starch crystallization.     

Manifestation of the size effect during crystallization and melting of dispersed water in native and amorphous starches with various degrees of hydration

Differential scanning calorimetry (DSC) was used to study the melting and crystallization of frozen water dispersed in humid potato starch. Melting and crystallization temperatures and heats as functions of the degree of hydration of the starch were obtained for native and amorphous starch states. Manifestations of the size effect were observed in the dependences of heat for the processes in both starch states. Crystallization and melting heats of frozen water were found to change nonlinearly with the increasing degree of hydration in all cases. In contrast, a size effect in the dependences of melting and crystallization temperatures of frozen water was detected only for native starch. Reasons responsible for the absence of a size effect in the amorphous state were considered. Hysteresis, which is characteristic of small particles, was observed upon melting and crystallization of frozen water and its manifestation strongly differed in the native and amorphous states of potato starch.     

Phase transitions of the starch–water system

When purified potato starch granules are heated in the presence of limited amounts of water (less than 1.5 H₂O: starch, w/w), two endothermic transitions are observed by differential scanning calorimetry. The lower temperature endotherm is always observed at a fixed temperature, 66°C; it is the only endotherm observed when excess water is present. The higher temperature endotherm is observed at increasing temperatures as the water content is decreased. The size of this endotherm decreases with water content. The appearance of the higher temperature endotherm allows the determination of the stoichiometry for full hydration of starch, 14 H₂O/hexose unit. The shift of the higher temperature endotherm is interpreted as the lowering of the melting point of starch crystallites by solvent water.     

Effect of amylose deposition on potato tuber starch granule architecture and dynamics as studied by lintnerization

The effect of amylose deposition on the amylopectin crystalline lamellar organization in potato starch granules was studied by mild acid, so‐called lintnerization, of potato tuber starch transgenically engineered to deposit different levels of amylose. The starch granules were subjected to lintnerization at different temperatures (25, 35, and 45°C) and to two levels of solubilization, ～ 45 and 80%. The rate of the lintnerization increased with temperature but was suppressed by amylose. The molecular size of the lintner dextrins increased with temperature, but this effect was suppressed by the presence of amylose. At high temperatures and low‐amylose content, the degree of branches was high with the concomitant increase in size in the dextrins. A portion of the branches was resistant to debranching enzymes possibly due to specific structural formations. The effects of temperature suggested a unique granular architecture of potato starch, and a model showing the dependence of temperature on the dynamic arrangement of amylopectin and amylose in the crystalline and amorphous lamellae for the potato starch is suggested. © 2012 Wiley Periodicals, Inc.     

Gelatinization and freeze-concentration effects on recrystallization in corn and potato starch gels

Freeze-concentration of starch gels was controlled by temperature and gelatinization with glucose and lactose. The aim of the study was to evaluate the effects of freezing temperature and gel composition on starch recrystallization behaviour of corn and potato starch gels (water content 70%, w/w) in water or glucose or lactose (10%, w/w) solutions. Starch gels were obtained by heating in differential scanning calorimetry (DSC). Samples of starch gels were frozen at -10 degrees C, -20 degrees C and -30 degrees C for 24h and, after thawing, stored at +2 degrees C for 0, 1, 2, 4 and 8 days. The extent of starch recrystallization was taken from the enthalpy of melting of the recrystallized starch by DSC. Freezing temperatures, glucose, lactose and the origin of the starch affected the recrystallization behaviour greatly. The recrystallization of amorphous starch during storage was enhanced by freeze-concentration of gels at temperatures above T'(m). Molecular mobility was enhanced by unfrozen water and consequently molecular rearrangements for nucleation could take place. Further storage at a higher temperature enhanced the growth and the maturation of crystals. In particular, glucose decreased the T'(m) of the gels and consequently lower freezing temperatures were needed to reduce enhanced recrystallization during storage. Freeze-concentration temperatures also showed a significant effect on the size and the perfection of crystals formed in starch recrystallization.     

Characterization of the Physical State of Spray-Dried Inulin

Modulated differential scanning calorimetry, wide angle x-ray scattering, and environmental scanning electron microscopy were used to investigate the physical and morphological properties of chicory root inulin spray dried under different conditions. When the feed temperature increased up to 80 °C, the average degree of polymerization of the solubilized fraction increased, leading to a higher glass transition temperature (Tg). Above 80 °C, the samples were completely amorphous, and the Tg did not change. The starting material was semicrystalline, and the melting region was composed of a dual endotherm; the first peak subsided as the feed temperature increased up to a temperature of 70 °C, whereas above 80 °C, no melting peak was observed as the samples were completely amorphous. To a lesser extent, the inlet air temperature of 230 °C allowed a higher amorphous content of the samples than at 120–170 °C but induced a blow-out of the particles.     

Phase separations in membranes of Anacystis nidulans grown at different temperatures

Freeze fracture electron microscopy studies were performed on samples of Anacystis nidulans quenched from different temperatures. Membrane lipid phase separations were observed to take place over the ranges 15–30°C, 5–25°C and –5–15°C for cultures grown at 38, 28 and 18°C, respectively. Differential scanning calorimetry heating curves showed endotherms which coincided with these temperature ranges. Variations of phase separation temperatures with growth temperature, and hysteresis effects in the calorimetric measurements, were related to changes in the fatty acid composition of membrane lipids.     

Physicochemical Characterization and Water Vapor Sorption of Organic Solution Advanced Spray-Dried Inhalable Trehalose Microparticles and Nanoparticles for Targeted Dry Powder Pulmonary Inhalation Delivery

Novel advanced spray-dried inhalable trehalose microparticulate/nanoparticulate powders with low water content were successfully produced by organic solution advanced spray drying from dilute solution under various spray-drying conditions. Laser diffraction was used to determine the volumetric particle size and size distribution. Particle morphology and surface morphology was imaged and examined by scanning electron microscopy. Hot-stage microscopy was used to visualize the presence/absence of birefringency before and following particle engineering design pharmaceutical processing, as well as phase transition behavior upon heating. Water content in the solid state was quantified by Karl Fisher (KF) coulometric titration. Solid-state phase transitions and degree of molecular order were examined by differential scanning calorimetry (DSC) and powder X-ray diffraction, respectively. Scanning electron microscopy showed a correlation between particle morphology, surface morphology, and spray drying pump rate. All advanced spray-dried microparticulate/nanoparticulate trehalose powders were in the respirable size range and exhibited a unimodal distribution. All spray-dried powders had very low water content, as quantified by KF. The absence of crystallinity in spray-dried particles was reflected in the powder X-ray diffractograms and confirmed by thermal analysis. DSC thermal analysis indicated that the novel advanced spray-dried inhalable trehalose microparticles and nanoparticles exhibited a clear glass transition (T _g). This is consistent with the formation of the amorphous glassy state. Spray-dried amorphous glassy trehalose inhalable microparticles and nanoparticles exhibited vapor-induced (lyotropic) phase transitions with varying levels of relative humidity as measured by gravimetric vapor sorption at 25°C and 37°C.     

Effect of the cross-linked reagent type on some morphological,physicochemical and functional characteristics of banana starch (Musa paradisiaca)

Cross-linked starches have increased their importance due to their applications such as adsorbents of heavy metals. In this work the effect the reagent used in the chemical modification of banana starch and its impact on some morphological, physicochemical and functional characteristics was evaluated. The reagent used in the cross-linked of starch decreased the fat and protein content, whereas ash level were higher. The morphology of the granules, observed by scanning electron microscopy, was more affected when a blend of sodium trimetaphosphate (STMP)/sodium tripolyphosphate (STPP) and epichlorohydrin (EPI) were used in the modification. The cross-linked starches presented a bimodal distribution and the effect was more conspicuous in those starches modified with STMP/STPP and EPI. The swelling value (60 °C) increased with the cross-linking and the highest value was obtained in those starches modified with STMP/STPP and EPI. However, at higher temperatures the swelling values of cross-linked starches with STMP/STPP and EPI decreased as temperature increased (80 °C), and there after the value was constant. The cross-linked starches with STMP/STPP and EPI showed the lowest solubility values. The cross-linked starch with POCl₃ (phosphorous oxychloride) showed a slight decrease in the onset and peak temperatures compared with its native counterpart, but those modified with STMP/STPP and EPI presented an increase in the three transition temperatures, but a decrease in enthalpy value. The results obtained can be used to determine the type of reagent used for cross-linked in order to obtain a starch with specific characteristics.     

A metabolic theory of ecology applied to temperature and mass dependence of N and P excretion by common carp

Our study used a metabolic theory of ecology (MTE) to explore scaling of metabolic rates by body size and temperature, and to predict nutrient excretion by common carp (Cyprinus carpio). At high biomasses, common carp have negative impacts on water quality, and one mechanism is excretion of the nutrients N and P. We measured whole-body and mass-specific excretion rates during summer and winter for fish of different sizes (wet mass range 28–1,196 g) to produce an allometric scaling model capable of predicting excretion at different temperatures. We found positive relationships between both dissolved and total nutrient concentrations and fish wet mass in summer and winter, with greater excretion rates in summer (mean water temperature 24.2°C) than in winter (mean water temperature 9.2°C). Mass-specific excretion rates decreased with increasing fish size, consistent with the MTE, and the temperature-adjusted model explained more variation for N excretion than for P. The proportion of dissolved nutrients (NH₄ and PO₄) to total nutrients increased with increasing fish size. The significance of these models is that they can be used to predict population-based nutrient excretion by common carp when thermal history, fish density and size distribution in a water body are known.     

Influence of amylopectin structure and degree of phosphorylation on the molecular composition of potato starch lintners

Morphology, molecular structure, and thermal properties of potato starch granules with low to high phosphate content were studied as an effect of mild acid hydrolysis (lintnerization) to 80% solubilization at two temperatures (25 and 45°C). Light microscopy showed that the lintners contained apparently intact granules, which disintegrated into fragments upon dehydration. Transmission electron microscopy of rehydrated lintners revealed lacy networks of smaller subunits. The molecular composition of the lintners suggested that they largely consisted of remnants of crystalline lamellae. When lintnerization was performed at 45°C, the lintners contained more of branched dextrins compared to 25°C in both low and intermediate phosphate‐containing samples. High‐phosphate‐containing starch was, however, unaffected by temperature and this was probably due to an altered amylopectin structure rather than the phosphate content. After lintnerization, the melting endotherms were broad with decreased onset and increased peak melting temperatures. The relative crystallinity was lower in lintners prepared at 45°C. A hypothesis that combines the kinetics of lintnerization with the molecular and thermal characteristics of the lintners is presented. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 257–271, 2014.     

Optimization of the spray drying of a Paenibacillus polymyxa-based biopesticide on pilot plant and production scales

Spore survival and moisture content are two important properties of biopesticides, and both are related to field biocontrol efficacy and storage shelf life. In this study, Paenibacillus polymyxa (HY96-2) was spray-dried on both pilot plant and production scales, and the effects of inlet and outlet temperatures on spore survival and moisture content were investigated. The results showed that inlet temperatures ranging from 170 to 230 °C (at an outlet temperature of 80 °C) had no obvious effect on the two properties during pilot scale processing, although an inlet temperature of 230 °C resulted in higher feed speed. When the outlet temperature on the pilot scale was reduced from 100 to 80 °C, no obvious variations in spore survival and moisture content were found, while a further reduction from 80 to 65 °C resulted in a decline in spore survival from 81.0 to 67.0% and an increase in moisture content from 2.3 to 31.7%. These results indicate that both outlet temperature and moisture content have an effect on spore survival. Optimum inlet and outlet temperatures for P. polymyxa processing were 230 °C and 85–90 °C on a production scale. Under these conditions, spore survival and moisture content were 83.5–86.6% and 2.73––4.12%, respectively.     

Pasting properties of a heat-moisture treated canna starch in relation to its structural characteristics

Native and moistened canna starches (moisture contents of 15%, 18%, 20%, 22%, and 25%) were heat treated at 100 °C for 16 h. Heat-moisture treatment (HMT) did not alter the shape or size of starch granules. Heat-treated starches showed lower paste viscosity, more stable paste (with no breakdown) and noticeable decrease in setback value compared to untreated native starch. These changes were more obvious when the starch samples contained more moisture. Starch gel morphology investigated by I₂ staining revealed that the granules of untreated native canna starch were completely ruptured, whereas those of HMT22% and HMT25% samples remained in granular form. These gel morphologies were correlated and provided the information to explain the pasting behaviors of treated and untreated canna starches. Shifts of gelatinization endotherms towards higher temperatures (1–8 °C) with broadened peaks following the moisture contents in starch samples were found after HMT. Amylose leaching of treated samples tended to be lower when the moisture content of the samples increased. HMT did not alter crystalline type of canna starch (B-type), but with increase of the moisture, slight reduction of a peak at 5.7° and a fusion of doublet at 22° and 24° were observed.     

Effects of open-top chambers and substrate type on biogeochemical processes at disturbed boreal forest sites in northwestern Quebec

In the context of land use change, the dynamics of the water extractable organic carbon (WEOC) pool and CO₂ production were studied in soil from a native oak-beech forest and a Douglas fir plantation during a 98-day incubation at a range of temperatures from 8°C to 28°C. The soil organic carbon, water contents and mineralisation rates of soil samples from the 0–5 cm layer were higher in the native forest than in the Douglas fir plantation. During incubation, a temperature-dependent shift in the δ¹³C of respired CO₂ was observed, suggesting that different carbon compounds were mineralised at different temperatures. The initial size of the WEOC pool was not affected by forest type. The WEOC pool size of samples from the native forest did not change consistently over time whereas it decreased significantly in samples from the Douglas plantation, irrespective of soil temperature. No clear changes in the δ¹³C values of the WEOC were observed, irrespective of soil origin. The fate of the WEOC, independent of soil organic carbon content or mineralisation rates, appeared to relate to forest types. Replacement of native oak-beech forest with Douglas fir plantation impacts carbon input to the soil, mineralisation rates and production of dissolved organic carbon.     

The impact of heating on the hydraulic properties of soils sampled under different plant cover

The impact of heating on the peristence of water repellency, saturated hydraulic conductivity, and water retention characteristics was examined on soils from both forest and meadow sites in southwest Slovakia shortly after a wet spell. The top 5 cm of meadow soils had an initial water drop penetration time WDPT at 20°C of 457 s, whereas WDPT in the pine forest was 315 s for the top 5 cm and 982 s if only the top 1 cm was measured. Heating soils at selected temperatures of 50, 100, 150, 200, 250 and 300°C caused a marked drop in water drop penetration time WDPT from the initial value at 20°C. However, samples collected in different years and following an imposed cycle of wetting and drying showed much different trends, with WDPT sometimes initially increasing with temperature, followed by a drop after 200–300°C. The impact of heating temperature on the saturated hydraulic conductivity of soil was small. It was found for both the drying and wetting branches of soil water retention curves that an increase in soil water repellency resulted in a drop in soil water content at the same matric potential. The persistence of soil water repellency was strongly influenced by both the sampling site and time of sampling, as it was characterized by the results of WDPT tests.     

Purification and characterization of thermostable β-amylase and pullulanase from high-yielding Clostridium thermosulfurogenes SV2

Thermostable β-amylase and pullulanase, secreted by the thermophilic anaerobic bacterium Clostridium thermosulfurogenes strain SV2, were purified by salting out with ammonium sulphate, DEAE-cellulose column chromatography, and gel filtration using Sephadex G-200. Maltose was identified as a major hydrolysis product of starch by β-amylase, and maltotriose was identified as a major hydrolysis product of pullulan by pullulanase. The molecular masses of native β-amylase and pullulanase were determined to be 180 and 100 kDa by gel filtration, and 210 and 80 kDa by SDS–PAGE, respectively. The temperature optima of purified β-amylase and pullulanase were 70 and 75°C, respectively, and both enzymes were completely stable at 70°C for 2h. The presence of starch further increased the stability of both the enzymes to 80°C and both displayed a pH activity optimum of 6.0. The starch hydrolysis products formed by β-amylase action had β-anomeric form.     

Thermal porosity analysis of croscarmellose sodium and sodium starch glycolate by differential scanning calorimetry

The aim of the study was to demonstrate the applicability of differential scanning calorimetry (DSC) on porosity analysis for cellulose and starch. Croscarmellose sodium (CCS) and sodium starch glycolate (SSG) were allowed to sorb moisture in 85%, 90%, 95%, and 100% relative humidity (RH) at 40°C for 24 hours. The pretreated samples were then subjected to DSC running temperature ranging from 25°C to −50°C at a cooling rate of 10°C/min. The cooling traces of water crystallization, if present, were transformed to porosity distribution via capillary condensation using Kelvin's equation. The porosity analysis of CCS and SSG was also done using nitrogen adsorption as a reference method. It was found that sorbed water could not be frozen (in cases of 85% and 90% RH) until the moisture content exceeded a cutoff value (in cases of 95% and 100% RH). The nonfreezable moisture content was referred to tightly bound, plasticizing water, whereas the frozen one may be attributed to loosely bound water condensation in pore structure of CCS and SSG surfaces. Not only capillary condensation but also the tightly bound, nonfreezable monolayer water lying along the inner pores of the surface contributed to porosity determination. Good agreement with less than 5% deviation of mean pore size was observed when the results were compared with nitrogen adsorption. The narrower pore size distributions, however, were obtained because of the limitations of the technique. It was concluded that pore analysis by DSC could be successful. Further research needs to be done to account for limitations and to extend the applicability of the technique.     

Pisum sativum and vicia faba carbohydrates: Part IV — Granular structure of wrinkled pea starch

The granular structure of wrinkled pea starch, compared to two other B-type starches, potato and amylomaize, has been studied, using physical, chemical and enzymic methods both before and after lintnerisation (2·2n HCl, 35°C). Wrinkled pea starch, which was composed mainly (90%) of compound granules, had an apparent amylose content of 75·4% when measured at +2°C. Native granules showed weak B-type crystallinity. The fraction (27·4%) which was easily degraded during lintnerisation and which corresponded to the amorphous phase, was smaller than for other starches. The degradation rate of the more organised phase was low (6% in 17 days). The residue remaining after exposure to acid for 42 days presented a very high, B-type crystallinity but with the same sorption properties as native starch, which indicates that water is part of the crystallites. The crystalline phase is composed of linear chains of $\text{DP}$ 25, distributed asymmetrically. The native starch showed a single gelatinisation endotherm between 117 and 133°C and with a ΔH of 0·7 cal. g^?1 dry starch, which is somewhat lower than other B-type starches.     

Structural and thermodynamic properties of rice starches with different genetic background Part 2. Defectiveness of different supramolecular structures in starch granules

High-sensitivity differential scanning microcalorimetry (HSDSC), small-angle X-ray scattering (SAXS), light (LM) and scanning electronic (SEM) microscopy techniques were used to study the defectiveness of different supramolecular structures in starches extracted from 11 Thai cultivars of rice differing in level of amylose and amylopectin defects in starch crystalline lamellae. Despite differences in chain-length distribution of amylopectin macromolecules and amylose level in starches, the invariance in the sizes of crystalline lamellae, amylopectin clusters and granules was established. The combined analysis of DSC, SAXS, LM and SEM data for native starches, as well as the comparison of the thermodynamic data for native and annealed starches, allowed to determine the structure of defects and the localization of amylose chains in crystalline and amorphous lamellae, defectiveness of lamellae, clusters and granules. It was shown that amylose “tie chains”, amylose–lipid complexes located in crystalline lamellae, defective ends of double helical chains dangling from crystallites inside amorphous lamellae (“dangling” chains), as well as amylopectin chains with DP 6–12 and 25–36 could be considered as defects. Their accumulation can lead to a formation of remnant granules. The changes observed in the structure of amylopectin chains and amylose content in starches are reflected in the interconnected alterations of structural organization on the lamellar, cluster and granule levels.