Showing papers in "Starch-starke in 1999"
TL;DR: In this article, the authors compared protein extraction solutions such as aqueous solutions of sodium hydroxide (0.1 and 0.2 %), sodium lauryl sulfate (SLS), 1.12 %, and dodecylbenzene sulfonate (DoBS, 1.5 %), and found that DoBS was more effective in removing rice protein whereas SLS was least.
Abstract: Protein extraction solutions such as aqueous solutions of sodium hydroxide (0.1 and 0.2 %), sodium lauryl sulfate (SLS, 1.2 %) containing sodium sulfite (0.12 %), and dodecylbenzene sulfonate (DoBS, 1.2 %) containing sodium sulfite (0.12 %) were compared in their protein removal efficiencies during isolation of starch from a rice flour (Ilpumbyo, a nonwaxy Korean rice variety). In addition, the pasting properties of the isolated starch was compared. More than 80 % of the flour protein was extracted in 1 h by stirring the dispersion (1:3, w/v) at room temperature. Repeating the extractions (1 or 2 h for each step) with fresh solution significantly increased the protein removal efficiency. When the extraction in 0.2 % NaOH was repeated four times (1 h for each step) at 25°C, the residual protein content in the isolated rice starch was 0.9 % (DB), equivalent to 86 % removal of the rice protein. Raising the extraction temperature slightly increased the protein solubility, but starch loss also became significant. Among the solutions, DoBS was most effective in removing rice protein whereas SLS was least. The residual protein content had a critical role in determining the pasting characteristics of the isolated starch, showing a negative correlation to the peak viscosity of the starch paste, but a positive correlation to the pasting temperature.
192 citations
TL;DR: In this paper, the effect of chemical modification on the physical properties of cross-linked and acetylated normal (NR) and waxy (WR) rice starch was investigated, and the results showed that both acetylation and cross-linking decreased retrogradation of NR, but increased it in WR.
Abstract: Waxy and normal starches present wide biological diversity in their structure. The objective of this study was to investigate the effect of chemical modification on the physical properties of cross-linked and acetylated normal (NR) and waxy (WR) rice starch. Cross-linking increased shear stability and decreased swelling power and solubility of NR and WR, but increased viscosity, pasting temperature, and heat of gelatinization of WR, and decreased pasting temperature and heat of gelatinization of NR. Acetylation increased viscosity and solubility of NR and WR, while it increased the swelling power of NR, and decreased the swelling power of WR. Cross-linking increased hardness and adhesiveness of NR and WR gels, while acetylation increased hardness but decreased adhesiveness of the gels. Freeze-thaw stability results showed that both acetylation and cross-linking decreased retrogradation of NR, but increased it in WR.
181 citations
TL;DR: In this article, a systematic study was performed to determine how changes in the starch concentration, starch/anhydride ratio, pH, temperature, and reaction time affect the efficiency of esterification.
Abstract: Starch esters prepared by modifications with hydrophobic alkenyl succinic anhydrides provide an opportunity to regulate the hydrophobic characteristics of these products. This is of great interest since many potential applications of modified starch products exploit their amphiphilic character. The objective of this work was to develop a greater understanding of how the reaction parameters in aqueous slurry reactions affect the efficiency of starch modification with dodecenyl succinic anhydride (DDSA). A systematic study was performed to determine how changes in the starch concentration, starch/anhydride ratio, pH, temperature, and reaction time affect the efficiency of esterification. Surprisingly, variations in the starch concentration (25 to 65 % w/w relative to water) at a 10 % anhydride concentration (w/w relative to starch) caused little change in the reaction efficiency. Maintaining the reaction within a pH range of 8.5–9.0 and at a temperature between 22 and 27 °C was preferred. The reaction efficiency decreased as the ratio of anhydride to starch increased. Also, extending the reactions beyond 48 h resulted in products of lower substitution. After a set of preferred reactions conditions were established, a comparison of reaction efficiencies as a function of the n-alkenyl chain length of the anhydrides used was performed. As the alkenyl chain length increased from 8 to 18 carbons a substantial decrease in the reaction efficiency occurred.
156 citations
TL;DR: Results strongly suggest that factors regulating the varietal difference in patterns of chain length of amylopectin are dissimilar to those causing the temperature effects on amylipectin fine structure in rice endosperm.
Abstract: The structure of endosperm amylopectin was compared between two rice varieties, Kinmaze (subspecies japonica) and IR36 (subspecies indica), as well as their waxy mutants, all grown under controlled temperature. The distinct varietal difference in chain length distribution of amylopectin was confirmed by high performance anion-exchange chromatography equipped with pulsed amperometric detection. Amylopectin from Kinmaze contains more very short chains with degree of polymerization (DP) between 6 and 10 and less chains with DP from 13 to 22 than amylopectin from IR36, while there is little difference in the distribution of longer chains with DP > 24 between the two varieties. Waxy mutation had little effect on chain length distribution of endosperm amylopectin. The temperature during grain-filling affected the chain length distribution of amylopectin in both varieties in a similar way; grain-filling at lower temperatures lead to an increased proportion of chains of DP 6—13 and decreased the percentage of chains with DP 20—27 and DP 44—54. However, the temperature-dependent changes in chain length distribution of amylopectin were within the range of varietal difference between Kinmaze and IR36. These results strongly suggest that factors regulating the varietal difference in patterns of chain length of amylopectin are dissimilar to those causing the temperature effects on amylopectin fine structure in rice endosperm.
136 citations
TL;DR: An environmentally friendly wood adhesive was developed by crosslinking cornstarch and polyvinyl alcohol (PVOH) with hexamethoxy-methylmelamine (Cymel 323) as discussed by the authors.
Abstract: An environmentally friendly wood adhesive was developed by crosslinking cornstarch and poly(vinyl alcohol) (PVOH) with hexamethoxy-methylmelamine (Cymel 323). Citric acid was used as a catalyst and latex (UCar 443) was added to improve moisture resistance. The adhesive was evaluated for its utility in plywood manufacture. It exhibited excellent mechanical properties comparable to many of the commercially available urea-formaldehyde plywood adhesives used for interior applications. The viscosity of the adhesive at 27 % (w/v) was 7000 mPas, allowing easy application to wood surfaces by brush. The minimum concentration of crosslinking agent needed to achieve good mechanical properties in plywood was 15 % (w/w proportion of total solids). Optimum curing temperature and curing time were 175 °C and 15 min, respectively. Addition of latex to the adhesive formulation improved both moisture resistance and physical properties of plywood test samples. Samples prepared with an optimal adhesive formulation, when completely immersed in water for 2 h or exposed at 93 % or 50 % relative humidity (RH) for 30 days, exhibited > 90 % failure in the veneer as opposed to < 10 % failure in the adhesive joints.
98 citations
TL;DR: The results show that the RS content in toast bread could be increased by approximately 3%, when 7.5% citrate starch was added, compared to non-fortified bread.
Abstract: Chemically modified starch was used as resistant starch (RS) to enhance the dietary fibre content in foods. Citrate starch was produced by esterification of starches of various origins and added to toast bread, wafers, pasta and extruded products. The RS content as well as relevant product features were determined and results compared to those of products without any citrate starch addition. The results show that the RS content in toast bread could be increased by approximately 3%, when 7.5% citrate starch was added, compared to non-fortified bread. Changes in product features due to addition of citrate starch could be compensated for by variation in the recipe, such as increasing the amount of water. Thus, appealing products could be obtained with an enriched dietary fibre content. The extend of the RS enhancement depends highly on the food system chosen.
80 citations
TL;DR: The physiochemical changes of starch in maize tortillas and their intermediate products commercially processed by the traditional way have been determined in this article, where samples of maize, nixtamal, dough or masa, tortilla and nejayote (steep liquor) were analyzed.
Abstract: The physiochemical changes of starch in maize tortillas and their intermediate products commercially processed by the traditional way have been determined. Samples of maize, nixtamal, dough or masa, tortilla and nejayote (steep liquor) were analyzed. The samples were assayed for water absorption index (WAI), resistant starch (RS), X-ray diffraction patterns, viscosity and with Differential Scanning Calorimetry (DSC). Enthalpy of fusion (ΔH), initial temperature (T o ) and transition temperature (T p ) of gelatinization were obtained from DSC curves. Resistant starch contents increased as the products advanced in the process. Significant differences (p > 0.05) in the fusion enthalpy values of maize, nixtamal and masa could not be found. X-ray diffraction patterns of maize, nixtamal and masa did not show significant changes; however, when masa was transformed into tortillas there was a large loss in crystallinity. The viscoamylograph peak viscosities increased from maize to masa and decreased drastically in tortillas. The data showed that the tortilla baking stage caused the most pronounced changes in starch.
79 citations
TL;DR: In this article, the octanoate of starch was prepared by gelatinization of native starch with formic acid, followed by treatment with octanoyl chloride, and it was readily carried out under a stream of N 2 at a stirring rate of 500 min -1 at 25-130 °C for a reaction duration of 20-120 min.
Abstract: An efficient method of synthesizing fatty acid esters of starch without organic solvents is described. The octanoate of starch was prepared by gelatinization of native starch with formic acid, followed by treatment with octanoyl chloride. Esterification was readily carried out under a stream of N 2 at a stirring rate of 500 min -1 at 25-130 °C for a reaction duration of 20-120 min. Formic acid enabled esterification of starch by long-chain acyl chlorides with minimum degradation. The major factors affecting the esterification reaction were optimized. The results indicated that the octanoyl degree of substitution (DS 8 ) was increased with increase in fatty acid chloride concentration (from 3-12 eq. per anhydroglucose unit) and rise in temperature (25 °C to 130 °C). Higher octanoyl chloride concentrations and temperatures led to a reduction in yield due to acid hydrolysis of starch chains. A maximum DS 8 of 1.7 was reached after 40 min of reaction, and high concentrations of formic acid decreased the octanoyl substitution. On the other hand, higher concentration of octanoyl chloride, higher temperatures and longer reaction times increased the substitution of the long acyl chain into starch.
74 citations
TL;DR: Amaranthus cruentus and quinoa were isolated and investigated by using enzymatic assay, Rapid Visco Analysis (RVA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and X-ray Diffractometry (XRD).
Abstract: Starches from amaranth (Amaranthus cruentus) and quinoa (Chenopodium quinoa) were isolated and investigated by using enzymatic assay, Rapid Visco Analysis (RVA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and X-ray Diffractometry (XRD) Amylose content measured enzymatically was 78 and 112 % for amaranth and quinoa starch, respectively Quinoa starch was much more viscous than amaranth starch and gelatinized at a lower temperature as determined with RVA DSC demonstrated a wider gelatinization temperature range for amaranth starch (206°C) than for quinoa starch (111°C) SEM observation revealed polygonal shape of starch granules, and XRD suggested a typical Atype diffraction pattern for both the starches in question A crystallinity of 455 % for amaranth and 354 % for quinoa starch, respectively, was also determined from the XRD collected data
73 citations
TL;DR: Improvements that have been made in glucoamylase industrial properties by protein engineering are reviewed.
Abstract: Glucoamylase is produced in higher tonnage than almost any other industrial enzyme. However, glucoamylase would be even more useful if it were more thermostable and selective in producing glucose. Extensive work to improve these properties has been conducted by site-directed mutagenesis of selected amino acid residues. Combining favorable mutations has decreased the ability of the enzyme to produce isomaltose, the main byproduct, in the glucoamylase-catalyzed production of glucose by almost half, has increased enzyme thermostability fourfold, and has increased enzyme activity by 15%. In addition, others have successfully improved catalytic efficiencies for maltose hydrolysis over isomaltose hydrolysis by mutations of glucoamylase. This article will review the improvements that have been made in glucoamylase industrial properties by protein engineering.
65 citations
TL;DR: In this article, three-phase nozzle separators equipped with wash water supply and constructed for efficient displacement washing allow to achieve a fine fibre removal of 98 % within three separation stages and a final concentration of purified starch milk of 22 to 23°Be.
Abstract: Potato starch production encountered drastic changes during the last years, in particular in economics and substrate supply. Because of economically required reductions in subsidisation, production of potato starch will decrease. Changes in technology are characterised by savings in wash water and process water streams that are effected by increased efficiency introduced with new machinery and changed technological concepts. From an ecological point of view, an early and maximum fruit water separation (up to 95 %) based on dilution of gratings with process water and decanter separation allowed to reduce the fresh water supply to 0.4 to 0.5 m 3 /t of processed potatoes. For economical isolation of potato protein a correspondingly high protein recovery rate (up to 90%) is essential. Concerning starch extraction, a minimum of 95 % is reached in modern potato starch plants, but optimum engineering (rasping, decanting, sieving) gives recovery rates of 97 to 98 %. In starch refinement, three-phase nozzle separators equipped with wash water supply and constructed for efficient displacement washing allow to achieve a fine fibre removal of 98 % within three separation stages and a final concentration of purified starch milk of 22 to 23°Be. Potato protein isolates (protein content 83 to 85 %) are produced by isoelectric precipitation combined with heat coagulation while stringent solutions for treatment of de-proteinised fruit water are still lacking.
TL;DR: The independent localisation of amylose and amylopectin in a range of dry and hydrated native starch granules with varying amylosity content (0-70 %) has been indirectly visualised using enzyme-gold cytochemical markers as mentioned in this paper.
Abstract: The independent localisation of amylose and amylopectin in a range of dry and hydrated native starch granules with varying amylose content (0-70 %) has been indirectly visualised using enzyme-gold cytochemical markers. Increasing amylose content was clearly demonstrated to result in distinct changes in granule architecture. In the absence of amylose (waxy maize starch) a framework of closely packed concentric layers of amylopectin exists in the granules. Low amylose content (potato starch) results in alternating layers of densely packed amylopectin and amylose molecules. High amylose content (amylomaize starch) granules were shown to possess an amylopectin centre surrounded by an amylose periphery encapsulated by an amylopectin surface. Elongated granules without the amylopectin centre were also observed in high amylose starches suggesting a relationship between amylopectin, amylose and granule shape. A model of starch granule architecture is proposed where increased compartmentalisation of amylose and amylopectin is observed in granules containing increasing levels of amylose.
TL;DR: A solvent-free synthesis and properties of esters of starch from different sources (maize, waxy maize, Eurylon 7, potato, wheat, rice, amylose, and amylopectin) and higher fatty acids are described in this paper.
Abstract: A solvent-free synthesis and the properties of esters of starch from different sources (maize, waxy maize, Eurylon 7, potato, wheat, rice, amylose, and amylopectin) and higher fatty acids are described Higher fatty acid esters (C 8 -C 18 ) of potato starch were synthesized by chemical gelatinization using formic acid, followed by treatment with fatty acid chlorides Esterification was readily carried out at 105 °C and a reaction time of 40 min Formic acid permits esterification of starch by long-chain acid chlorides with minimum degradation The results indicated that the degree of substitution of the starch esters diminishes with increase in fatty acid chain length All starch esters have a hydrophobic character which rises with length of the fatty side chain X-ray and Differential Scanning Calorimetry (DSC) showed that the fatty acid side 1 chains (C n > 16) grafted onto starch form cristallites between them This phenomenon provokes the decrease of elongation at break for these starch esters On the other hand, the tensile strength at break and thermal stability of fatty esters of starch increase both with a higher fatty chain grafted onto starch
TL;DR: In this article, the effects of the irradiation on the transition enthalpy and temperature for melting, and the pasting viscosity profile of corn starch molecules were examined.
Abstract: Suspension (30%, w/w) of corn starch (25 % amylose) in water was irradiated by UV-light with wavelength greater than 250 nm at 25 °C, under a stream of nitrogen or air, for time intervals ranging from 5 to 25 h. Effects of the irradiation on the transition enthalpy and temperature for melting, and the pasting viscosity profile of the irradiated starch were examined. Weight-average molecular weight (M w ) and radius of gyration (R g ) of the irradiated starch molecules were measured by high performance size exclusion chromatography coupled with multiangle laser light scattering and differential refractive index detectors (HPSEC-MALLS-RI). In the case of starch irradiated under nitrogen, the transition enthalpy (ΔH) decreased with increasing irradiation time whereas the melting temperature was not changed. Similarly, the peak paste viscosity (P v ) decreased from 97 to 56 RVU by 25h irradiation. Average M w and R g of amylopectin and amylose fractions, which were 93 x 10 6 and 144nm, and 2.0 x 10 6 and 104nm, respectively, were decreased by irradiation to 32.2 × 10 6 and 93.7 nm, and 0.7 x 10 6 and 83.6 nm by the irradiation for 15 h under nitrogen, respectively. When the starch was irradiated with aeration, sharp drops of all measured parameters were observed in 5 h of irradiation (ΔH 11.4J/g, P v 53.2 RVU, amylopectin M w 50 x 10 6 ). After 15 h under air, however, all measured values increased (ΔH 16.8J/g, P v 65.5 RVU, amylopectin M w 63.1 × 10 6 ). Molecular size distribution profiles confirmed oxidative the photodegradation in the early stage (up to 5 h), and cross-linking reactions in the late stage (5-15 h) of irradiation under aeration.
TL;DR: In this article, a wide angle X-ray diffraction measurements revealed A-type diffraction patterns and the gelatinization behavior of common wheat and durum wheat starches was investigated.
Abstract: Starches from 3 common wheats and 10 durum wheats were isolated using a method causing little starch damage and annealing. Durum wheat starches contained 0.21–0.29 % ash, 0.44–0.57 % protein, 0.39–0.54 % lipid, and 26.2–28.5 % amylose. Wide angle X-ray diffraction measurements revealed A-type diffraction patterns. Durum wheat starches gelatinised over a broad temperature range (12.5 °C) around 55.5 °C (peak temperature), as measured with Differential Scanning Calorimetry (DSC) (starch/water = 1/2; heating rate = 4 °C/min). Under the experimental conditions, swelling power was typically 11.3 g/g and amylose leaching during gelatinisation was ca. 17.2 %. The granule size distributions showed a large heterogeneity within the starches of the durum wheat family. Clear differences were found in the gelatinisation behaviour of durum and common wheat starches. Earlier swelling of the common wheat starches during gelatinisation and the larger enthalpy of amylose-lipid endothermic transition (ca. 1.3 mJ/mg) in the DSC for durum wheat starches can be explained in terms of true lipid contents and levels of amylose-lipid inclusion complexes. Other findings, such as the earlier gelatinisation behaviour of durum wheat starches revealed by DSC, cannot be explained in that way. Differences in starch double helix content between the two wheat families were found.
TL;DR: In this paper, Waxy maize, amaranth, quinoa, wheat, millet and buckwheat starches were investigated with respect to their technological properties such as gelatinization, stability to mechanical stress, resistance to conditions and stability in continuous freeze/thaw cycles.
Abstract: Selected starches, i.e. waxy maize, amaranth, quinoa, wheat, millet and buckwheat starches, were investigated with respect to their technological properties such as gelatinization, stability to mechanical stress, resistance to conditions and stability in continuous freeze/thaw cycles. Technological properties are correlated with molecular features such as branching characteristics in terms of iodine-complexing potential, molar mass, occupied glucan-coil volume, packing density of glucan coils and rheological properties. Waxy maize and amaranth starches were found to be amylopectin-type short-chain branched (scb) glucans with weight average molar masses M w = 17 × 10 6 g/mol and 12 × 10 6 g/mol, respectively. Waxy maize starch had a high gelatinization potential, high viscosity at 95 °C (340 mPas) low stability at acidic conditions, average stability to shearing and good freeze/thaw stability. For amaranth starch a viscosity of 122 mPas at 95°C, low resistance to acid, but high stability to applied shearing and even high freeze/thaw stability was determined. Investigated quinoa starch was classified as scb-type glucan, however, the branches are significantly longer than those of waxy maize and amaranth. With a M w = 11 × 10 6 g/mol and a viscosity of 187 mPas at 95°C, this sample is comparably resistant to acidic conditions and to shearing, but instable in freeze/thaw experiments. Wheat, millet and buckwheat starches contain significant percentages of amylose-type long-chain branched (lcb) glucans (22.1, 32.1 and 24.3%, respectively) with M w values of 5 × 10 6 g/mol, 12 × 10 6 g/mol and 15 × 10 6 g/mol, respectively. Wheat starch, with a viscosity of 107 mPas at 95°C, shows low stability under acidic conditions, but high stability to shearing. Wheat and millet starches, but not buckwheat starch, form weak gels in the course of subsequent freeze/thaw cycles. Millet starch, with a viscosity of 101 mPas at 95 °C was found to be moderately stable under acidic conditions and to shearing. Buckwheat starch with a viscosity of 230 mPas at 95 °C shows no acid resistance and is instable upon shearing but performs very well in freeze/thaw experiments.
TL;DR: In this paper, 3 types of differently prepared carboxymethyl starches were analyzed by HPLC and 1H-NMR spectroscopy after chain degradation, and a significant amount of 2,3,4,6-tetra-O functionalization caused by the branched structure of starch was found.
Abstract: Three types of differently prepared carboxymethyl starches were analyzed by HPLC and 1H-NMR spectroscopy after chain degradation. In derivatives obtained in the conventional manner with values of the degree of substitution (DS) up to 0.85; glucose, mono- and di-O-carboxymethyl glucose were detected as building units. Comparison with statistic calculations revealed an even distribution of functional groups along the chain. 1H-NMR studies confirmed a preferred substitution at the 2 position of the repeating unit. Comparable results were obtained for the carboxymethyl ether of amylose, amylopectin and β-cyclodextrin. The analysis of carboxymethylated starch samples prepared using a new synthesis concept via a reactive microstructure revealed a high DS achieved in a one-step synthesis as well as a non-statistic distribution of carboxymethyl groups along the chain. A significant amount of 2,3,4,6-tetra-O-functionalization, caused by the branched structure of starch, was found. Moreover, carboxymethylation of 6-O-triphenylmethyl starch and subsequent detritylation yields a regioselectively functionalized polymer consisting not only of the expected mono- and di-O-carboxymethylated repeating units but also containing a significant amount of 2,3,4-tri-O-functionalized anhydro-glucose units.
TL;DR: Microscopical studies showed that endocorrosion, i.e., breakdown starting from the center of starch granules, was the main pattern observed during lentil fermentation.
Abstract: Lentil seeds (Lens culinaris var. vulgaris, cultivar Magda-20) were allowed to ferment naturally at different lentil flour concentrations (79 g/L, 150 g/L and 221 g/L) and temperatures (28 °C, 35 °C and 42 °C). During fermentation, samples were taken at 24 h intervals. The changes in starch content in all samples were studied. Scanning electron microscopy (SEM) was used to investigate changes in samples fermented for 96 h at two different concentrations (79 g/L and 221 g/L) and two different temperatures (28 °C and 42 °C). A considerable decrease in starch content was observed at 0 h of fermentation, defined as the time when the lentil flour was completly suspended at the established temperature. Once fermentation began, flour concentration and temperature modified starch content. Fermentation brought about a general decrease in starch content and a 32—37 % dry matter content was found in the samples after 96 h. Microscopical studies showed that endocorrosion, i.e., breakdown starting from the center of starch granules, was the main pattern observed during lentil fermentation.
TL;DR: In this article, the amylose content of rice starches was separated using size exclusion chromatography coupled with multi-angle laser-light-scattering (SEC-MALLS) and the molecular weight and polydispersity value of amyloses were also reported.
Abstract: The amylose content separated from enzymatically debranched rice starches using Size Exclusion Chromatography Coupled to Multi-angle Laser-Light-Scattering (SEC-MALLS) ranged from 7-11 % of the total starch. This could be the true amylose content and is much lower than is obtained from iodine binding methods. The molecular weight and polydispersity value of the amyloses are also reported.
TL;DR: In this paper, the melting cooperative units for crystalline lamellae of the cereal starches were calculated, and the average value of the melting unit was determined, which is practically equal to the thickness of crystalline lambs in the amylopectin model.
Abstract: Some normal (maize, wheat, barley, rye) and high amylose (barley) starches were studied using the method of differential scanning microcalorimetry (DSC). It was shown that a decrease of heating rate from 3 K/min to 0.25 K/min for 1% aqueous dispersions of starch does not lead to changes of the thermodynamic melting parameters of crystalline lamellae irrespective of the origin of starches. With the exception of the results for maize starch, the same behavior is observed for melting of amylose-lipid complexes. For maize starch, a decrease of heating rate and an annealing of crystalline lamellae lead to an increase of melting enthalpy of amylose-lipid complexes but does not change their melting temperature. The melting cooperative units for crystalline lamellae of the cereal starches were calculated. Using the average value of the melting cooperative unit, the lamellar thickness was determined. It is practically equal to the thickness of crystalline lamellae in the amylopectin model proposed by Robin. It was shown that the temperature dependence of the heat capacity for starch maize lipids has a negative increment. Some concepts concerning melting mechanisms of crystalline lamellae and amylose-lipid complexes are discussed.
TL;DR: Analysis of starch produced from the transgenic plant shows that starch structure and properties have been altered, and various monocot vectors have been developed that drive expression of wheat starch branching enzyme I (SBEI) cDNA sequences in the anti-sense orientation.
Abstract: Natural mutations that affect the amylose/amylopectin ratio in starch are unlikely to develop naturally in wheat due to its allohexaploid genome (2n =6x; AABBDD). One of the strategies to modify wheat starch structure involves identification of germplasms with null alleles for starch biosynthetic genes, followed by exchange of functional alleles with the identified null alleles through classical plant breeding. This technique has successfully been used to combine the three null alleles for granule-bound starch synthase I (GBSSI) to develop a wheat line that produces amylopectin-rich (>95%) starch (waxy starch). Another strategy to alter expression levels of starch biosynthetic genes employs recent advances in molecular biology and genetic engineering of wheat. For this approach, various monocot vectors have been developed that drive expression of wheat starch branching enzyme I (SBEI) cDNA sequences in the anti-sense orientation. Several of the wheat cell lines transformed with the anti-sense vectors express branching enzyme (BE) activity at a significantly lower level than non-transformed cells. One transgenic wheat plant expressing the anti-sense SBEI RNA produces a ten-fold lower level of BE activity in kernels than wild-type wheat. Analysis of starch produced from the transgenic plant shows that starch structure and properties have been altered.
TL;DR: In this paper, the physicochemical properties of the starch extracted from oil palm trunk (Elaeis guineensis Jacq) were investigated, and the extraction of starch was achieved by using an aqueous solution containing 0.5% sodium metabisulphite.
Abstract: Physicochemical properties of the starch extracted from oil palm trunk (Elaeis guineensis Jacq.) were investigated. The extraction of starch was achieved by using an aqueous solution containing 0.5% sodium metabisulphite. Moisture content protein, lipid, ash and total amylose content were found to be 11.8, 0.9, 0.3, 1.03 and 19.5%, respectively. Measurement of starch granule size with a Coulter Counter revealed a bimodal distribution, with an average of 14.5 μm. Further studies on cross-section of oil palm trunk indicated that the starch granules were located intracellular. Examination of starch granules under a Scanning Electron Microscope exhibited both an oval and an elliptical shape with a truncated end. An X-ray diffraction investigation of this starch exhibited an A-type X-ray pattern. Percentage of swelling power and solubility determined at 90°C were found to be 33.1 and 30.8, respectively. Gelatinisation temperature obtained by Differential Scanning Calorimetry (DSC) ranged from 52.4°C to 72.1°C. with a peak melting temperature of 62.9 °C. The flow behaviour characteristics of oil palm trunk starch is pseudoplastic and viscosity depends on starch concentration, temperature and shear rate.
TL;DR: The method was used to demonstrate the variation in amylose content within single heads of an inbred tetraploid wheat and provided cleaner starch than earlier methods, as shown by higher apparentAmylose values, and was highly repeatable.
Abstract: To allow genetic analysis of starch quality in wheat and its relatives, it was necessary to develop techniques suitable for use on endosperm halves of seeds, leaving the embryo half to be grown for the next generation. Seeds were split and the endosperm end was crushed and soaked in 0.5 M NaCl overnight. The solids were ground three times in 0.5 M NaCl, the supernatant starch slurries were pooled and washed through a series of 4 M NaCl, 6 M NaCl/50 %, sucrose, 2 % sodium dodecyl sulphate solution, and acetone before being dried over silica gel. Subsamples of 1 mg of starch were dispersed in ethanol in preweighed microfuge tubes, gelatinised in NaOH solution, diluted to constant concentration, and aliquots were neutralised with citric acid, stained with iodine, diluted with water, and evaluated in an ELISA plate reader at 620 nm. The overall method provided cleaner starch than earlier methods, as shown by higher apparent amylose values, and was highly repeatable. The method was used to demonstrate the variation in amylose content within single heads of an inbred tetraploid wheat. No consistent patterns of variation due to seed location were detected but the overall breadth of variation around the median value of 27 % was ± 5 %.
TL;DR: In this paper, the thermodynamic behavior of dry native starch, amylose and amylopectin originating from different plants was investigated using Thermogravimetry and Differential Scanning Calorimetry (DSC).
Abstract: Thermal behavior of dry native starch, amylose and amylopectin originating from different plants was investigated using Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). The decomposition temperature increased as the molecular weight increased and a sudden increase was observed at a molecular weight of 50,000 that can be the critical value. DSC analyses verified that the amorphous phase in the specimens was swollen by bound water within a temperature range of 323–428 K. The change in swelling enthalpy divided by the peak temperature of swelling depended linearly on the volume fraction of bound water, regardless of the origin and the composition or purity of the specimens. Furthermore, bound water depressed the melting points of crystallites in the specimens, which agreed well with the prediction of Flory's lattice theory.
TL;DR: In this article, the authors investigated the simultaneous effects of viscosity and temperature on the productivity of the alcohol fermentation of starch hydrolysate by Saccharomyces cerevisiae.
Abstract: Aim of this work is to investigate the simultaneous effects of viscosity and temperature on the productivity of the alcohol fermentation of starch hydrolysate by Saccharomyces cerevisiae. Batch fermentations have been carried out at given pH, broth composition, inoculum, and agitation intensity, but at varying temperature (24
TL;DR: In this paper, a two-stage enzymatic treatment was used to transform starch-containing desizing liquors from the pretreatment of cotton fabrics into bleaching liquors by using cyclodextrins.
Abstract: Starch-containing desizing liquors from the pretreatment of cotton fabrics can be transformed into bleaching liquors by a two-stage enzymatic treatment. The bleaching ability of these liquors is comparable to that of conventional bleaching liquors. The process results in saving of ecologically harmful chemicals and process water. In enzymatic textile processes a loss of enzyme activity occurs, due to the presence of ionic surfactants. This loss of activity can be counteracted by addition of cyclodextrins. Trials have been done to immobilize glucose oxidase on the cheap carrier material cotton, so it can be used more often than only one time as regenerable enzyme.
TL;DR: In this paper, the authors compared four buckwheat cultivars introduced from Poland, France, and Russia and one of German origin by using enzymatic assay, Brabender Viscoamylography (BV), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and X-ray Diffractometry (XRD).
Abstract: Starch of four buckwheat cultivars introduced from Poland, France, and Russia and one of German origin were comparatively studied by using enzymatic assay, Brabender Viscoamylography (BV), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and X-ray Diffractometry (XRD). Amylose content of the starches measured with enzymatic analysis ranged from 21.3 to 26.4 %. The viscosities of buckwheat starches derived from BV were much higher than those of cereal starches. The gelatinization temperatures determined by DSC were lower than those obtained from BV. SEM observation revealed starch granules with oval, spherical, and polygonal shapes. XRD suggested typical A type pattern of X-ray diffraction for all starches in question and crystallinity varied from 38.3 to 51.3 %.
TL;DR: In this paper, a protocol was developed for molecular characterization of debranched starch amylopectin using Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS).
Abstract: A protocol was developed for molecular characterization of debranched starch amylopectin using Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). Starch from waxy corn was used in the protocol development. Various factors influencing the protocol were investigated and discussed. Using the developed protocols, starch amylopectin from barley grains (waxy-type Candle and regular-type Phoenix) were also characterized. The study suggested that MALDI-MS is suitable to determine the molecular size profile of debranched starch (maltooligo- and polysaccharides) faster and with greater accuracy than any present analytical methodology.
TL;DR: In this paper, the extrusion specific mechanical energy (SME) and the product of solubility and intrinsic viscosity of rice starch products were analyzed, indicating a close relationship between the energy input in the extrusions process and the performance behavior of the extruded phosphorylation products.
Abstract: Rice starch phosphates were prepared by the extrusion of rice starch with phosphate salts including sodium tripolyphosphate (STP), sodium trimetaphosphate (SMP), and a 50:50 mixture of STP and SMP (STP-SMP). The incorporation of phosphorus in the starch increased with increased barrel temperature ranging from 120 to 180 °C. At 180 °C, phosphorus contents for products treated with STP, SMP, and STP-SMP were 0.376, 0.194, and 0.360%, respectively. The effects of phosphorylation on functional and rheological properties of the starch varied, depending on the extent of molecular degradation and the formation of intermolecular cross-linking caused by the heat and shear of extrusion. Generally, extrusion stabilized the pasting properties of the extrudates, whereas phosphorylation enhanced the pasting consistency of the starch products. Good correlation was observed between the extrusion specific mechanical energy (SME) and the product of solubility and intrinsic viscosity, indicating a close relationship between the energy input in the extrusion process and the performance behavior of the extruded phosphorylation products.
TL;DR: A thermophilic soil isolate, Bacillus stearothermophilus KP1289, that grew from 41 °C to 69 °C, produced extracellular inulinases in the presence of inulin, and one (inulinase II) of these enzymes was purified to homogeneity.
Abstract: A thermophilic soil isolate, Bacillus stearothermophilus KP1289, that grew from 41 °C to 69 °C, produced extracellular inulinases in the presence of inulin. One (inulinase II) of these enzymes was purified to homogeneity. The molecular weight (M r ) and the isoelectric point of the enzyme were estimated as 54,000 and 5.0, respectively. The enzyme was active between 30 and 75 °C and at pH 4.5-8.6 with an optimum at 60 °C and pH 6.1. At 69 °C and pH 7.0 the half-life of the enzyme was 10 min. The enzyme released fructose exo-wise from the non-reducing end of inulin (M r = 4,5000). The Michaelis constant, catalytic center activity, and specificity constant for inulin at 60°C and pH5.0 were 80 mM (360 mg/mL), 460 s -1 , and 5.8 s -1 mM -1 , respectively. The ratio of specificity constants for inulin, sucrose, and raffinose was 1:0.50:0.16. The enzyme was classified as a thermophilic thermostable β-D-fructan fructohydrolase (EC 3.2.1.80).