Showing papers in "Starch-starke in 2002"
TL;DR: In this paper, a review of physicochemical and functional properties of tropical tuber starches is presented, highlighting their unique properties and potential field of applications, and the diversity available in the starches shows that some of them can be used in place of chemically modified starches available on the market.
Abstract: The tropical tuber crops contain starch as the major component and thus act as important source of starch. Except cassava and to a smaller extent sweet potato, starch from other tuber crops has not been exploited for industrial applications partly because of difficulty in the extraction of the pure starches and partly because of non-availability of information about the properties of these lesser known starches. This review attempts at collating data available on the physicochemical and functional characteristics of the tropical tuber starches, highlighting their unique properties and potential field of applications. The physicochemical properties like granule shape and size, X-ray diffraction (XRD) patterns, amylose content, or content of non-starchy components, show considerable variation among the tuber starches. In addition, factors like genetic origin, environmental conditions and age of the plant also influence the properties. The starch granules of Colocasia esculenta and Dioscorea esculenta tubers are very small whereas those of Canna edulis are very large. XRD patterns of yam starches are generally ‘B’, while the aroid starches possess ‘A’ patterns. DSC gelatinisation temperatures are low for cassava starch and high for the aroid starches. The functional characteristics like viscosity, swelling power and solubility also depend on a number of factors such as varietal variation, method of extraction, processing conditions and instruments used for analysis. Viscosity is high for cassava and C. edulis starches, but low for most aroid starches. Clarity is good for cassava and yam starches compared to the others. Digestibility also varies among the starches. The diversity available in the tuber starches shows that some of the starches can be used in place of chemically modified starches available on the market. The realisation of their importance can help in value addition of these neglected crops and also provide starch with special properties for specific applications.
476 citations
TL;DR: In this article, a review summarizes the present knowledge on composition, structure and physiochemical properties of smooth and wrinkled seeded pea starches with a view to providing suggestions for needed research to improve the utilization of pea starch in the food industry.
Abstract: Recently, pea has developed into a major protein crop in Western Canada. In the search for new food protein resources, small commercial facilities in Canada have engaged in manufacturing protein concentrates from pea by air classification or wet milling techniques. However, the major products from these processes are either crude or refined pea starches. Pea starch has been utilized almost exclusively for industrial application. A major factor, which has an adverse effect on the widespread utilization of pea starch in food industry, it its high extent of retrogradation. This review summarizes the present knowledge on composition, structure and physiochemical properties of smooth and wrinkled seeded pea starches with a view to providing suggestions for needed research to improve the utilization of pea starches in the food industry.
375 citations
TL;DR: Results show that the varietal difference in amylopectin structure is predominantly due to difference in lengths of A chains of the cluster and plays a critical role in determining the physicochemical properties of starch in the rice endosperm.
Abstract: 1 The present investigations have been performed to characterize the structure of amylopectin in endosperm of rice plants cultivated in Asian countries, and to determine the relationship between the amylopectin structure and physicochemical properties of the starch. The results indicated that almost all of rice amylopectin was distinctly classified into L-type or S-type. The L-type amylopectin was diffrent from the S-type amylopectin in that the numbers of short α-1, 4-glucan chains of DP ≤ 10 were less than 20% of the total α-1, 4-glucan chains of DP ≤ 24 in a single cluster in the former and those were higher than 24% in the latter, while no significant difference between both types was found in the proportion of B2 and longer chains of DP ≥ 25. Strikingly, among the 129 rice varieties examined, only a single variety cv. Khauk Yoe belonging to the Tropical Japonica rice group had an intermediate amylopectin structure between L-type and S-type, called M-type amylopectin. Apparently, the proportion of chains with DP ≤10 to those with DP ≤ 24 in amylopectin molecules was negatively correlated with the onset temperature of gelatinization of the starch, whereas no such correlation was observed between the amylose content and the thermal properties of starch. All these results show that the varietal difference in amylopectin structure is predominantly due to difference in lengths of A chains of the cluster and plays a critical role in determining the physicochemical properties of starch in the rice endosperm.
210 citations
174 citations
TL;DR: In this article, commercial rice starch, in aqueous slurry (42% starch solids), was acetylated with 6.3% acetic anhydride (on a dry starch basis).
Abstract: Commercial rice starch, in aqueous slurry (42% starch solids), was acetylated with 6.3% acetic anhydride (on a dry starch basis). The acetylated starch showed lower (P < 0.05) moisture, ash, crude protein, and apparent amylose content and pH than native starch. The crude fat and fiber, absolute density and titratable acidity were the same (P ≥ 0.05) in both starches. The percentage of acetyl groups and degree of substitution were 0.67% and 0.03, respectively. These groups caused an increase in water absorption, swelling power and solubility, which also affected the initial pasting temperature, viscosity at 90 °C, viscosity at 50 °C and setback; the acetylated starch showed a lower initial pasting temperature and setback than native starch, while both viscosity values increased. The morphology of acetylated rice starch was slightly modified.
163 citations
TL;DR: In this paper, the effects of the catalyst used in acetylation, including NaOH, KOH, and Ca(OH) 2, on the chemical and physicochemical properties of acetylated waxy maize starch were investigated.
Abstract: The effects of the catalyst used in acetylation, including sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH) 2 ), on the chemical and physicochemical properties of acetylated waxy maize starch were investigated. The Ca(OH) 2 -catalyzed acetylated starch exhibited a slightly higher pasting temperature and a lower β-amylolysis limit compared with acetylated starch prepared under NaOH or KOH catalysis, but no difference was observed for their thermal properties. The carbohydrate profiles of isoamylase-debranched acetylated starches and their p-limit dextrins were characterized by high-performance size-exclusion chromatography. The Ca(OH) 2 -catalyzed acetylated starch showed a elution profile that was different from those of the other two acetylated starches with a greater proportion of saccharides eluted at a longer retention time. However, the differences in pasting temperature, β-amylolysis limit, and carbohydrate profile among the acetylated starches diminished when ethylenediaminetetraacetic acid (EDTA) was added. The results suggest that calcium might induce intermolecular crosslinking through chelation with oxygen of the anhydroglucose units and this type of crosslinking was promoted in acetylation catalyzed by Ca(OH) 2 .
137 citations
TL;DR: Gelatinization of starch was studied by using modulated differential scanning calorimetry, nuclear magnetic resonance relaxometry, and confocal laser scanning microscopy as mentioned in this paper, where the effects of sugar or gum addition were analyzed in terms of changes in the gelatinization temperature and the effects on molecular mobility changes.
Abstract: Gelatinization of starch was studied by using modulated differential scanning calorimetry, nuclear magnetic resonance relaxometry, and confocal laser scanning microscopy. The effects of sugar or gum addition were analyzed in terms of changes in the gelatinization temperature and the effects on molecular mobility changes. Two states of water were found in both relaxation mechanisms (spin-spin and spin-lattice) and the extent of mobility depended on the concentration of the mixtures and the nature of the ingredients. With xanthan, dramatic changes of mobility were observed prior to gelatinization, indicating adsorption of xanthan on the starch granule surface. This result was confirmed by confocal scanning laser microscopy. The studies are contributing to the understanding of starch gelatinization in the presence of other substances. Potential industrial application is seen for the food industry (NMR as online method for gelatinization monitoring, synergistic thickening effects).
118 citations
TL;DR: Starch isolated from five grain tef (Eragrostis tef) varieties was characterized and compared with commercial maize starch as discussed by the authors, showing that Tef starch has higher water absorption index (WAI) and lower water solubility index (WSI) than maize starch.
Abstract: Starch isolated from five grain tef (Eragrostis tef) varieties was characterized and compared with commercial maize starch. Grain tef starch is formed of compound granules, comprising many polygonal shape (2—6 μm in diameter) simple granules. The crude composition is similar to that of normal native cereal starches. The amylose content ranges from 24.9—31.7%. Gelatinisation temperature range was 68.0—74.0—80.0 °C, typical of tropical cereal starches, and resembling the temperature range of rice starch. The mean intrinsic peak viscosity (269 RVU), breakdown viscosity (79 RVU), cold paste viscosity (292 RVU) and setback viscosity (101 RVU) determined were considerably lower than that of maize starch. Tef starch has higher water absorption index (WAI) (mean 108%) and lower water solubility index (WSI) (mean 0.34%) than maize starch.
93 citations
TL;DR: Floridean starch exhibited low gelatinization temperature, low viscosity, high clarity and little or no retrogradation upon repetitive freeze-thaw cycles, as studied by DSC and rapid viscosities analysis (RVA).
Abstract: The current work reports on isolation and physico-chemical characterization of floridean starch from three species of agarophytic macro red algae. As determined by 1H-NMR spectroscopy, the average chain length and degree of branching frequency of this starch were 18 and 4.8, respectively. According to its amylopectin chain length distribution obtained by Dionex analysis, the crystalline polymorph of floridean starch from the red alga Gracilariopsis lemaneiformis was deduced to be C-type and this was further supported from its X-ray crystallographic pattern. Enzymatic analysis of its glucose 6-phosphate content showed that floridean starch had a low level of covalently linked phosphate (1 nmol per milligram starch) and this was further confirmed by 31P-NMR. The absorbance peak of floridean starch with iodine occurred at 527—530 nm and the blue value was low (0.1), indicating the absence of amylose, which was confirmed by differential scanning calorimetry (DSC). Floridean starch exhibited low gelatinization temperature, low viscosity, high clarity and little or no retrogradation upon repetitive freeze-thaw cycles, as studied by DSC and rapid viscosity analysis (RVA). These results are discussed in light of the functional properties and the structure of floridean starch.
83 citations
TL;DR: In this paper, the influence of thermal energy input, expressed by the product temperature (PT), and specific mechanical energy input (SME) on the molecular structure of extruded starch was investigated.
Abstract: By using a systems analytical model (SAM) and a fuzzy logic control software (fuzzy CIM) extrusion experiments were designed, that enabled a differentiation of the influence of the thermal energy input, expressed by the product temperature (PT), and the influence of the specific mechanical energy input (SME) on the molecular structure of extruded starch. The chromatographic examination of the molecular changes in the starch clearly revealed the influence of the extrusion cooking conditions on molecular degradation.
The molecular size of extruded starch, expressed as the weight average of the molecular weight (Mw), decreased exponentially when SME increased. In the range of 110—180 °C, PT had no significant influence on Mw so that the observed reduction of Mw was primarily dependent on the increase in SME. By contrast, the polydispersity depended both on PT and SME. The influence of PT on the polydispersity was of minor significance up to 160 °C, increasing more steeply at higher temperatures. PT increase above 180 °C resulted in increasing reducing power of the extruded starch, whereas SME had almost no effect on reducing power. Only at a PT of more than 180 °C small amounts of short chain molecules with a degree of polymerisation (DP) smaller than 6 could be determined.
72 citations
TL;DR: In this article, a commercial hydrotalcite catalyst, namely DHT-4A2 from Kyowa, in its carbonate, hydroxide or mixed carbonate-hydroxide form was used for isomerization of glucose to fructose.
Abstract: Isomerization of glucose to fructose was performed in a batch mode at 363 K in the presence of a commercial hydrotalcite catalyst, namely DHT-4A2 from Kyowa, in its carbonate, hydroxide or mixed carbonate-hydroxide form. Catalysts in their total or partial hydroxide form were found to be both more active and slightly more selective for fructose than in the carbonate form. However, in all cases, the high selectivity observed (=? 90%) tends to drop relatively rapidly after 15% of glucose conversion. Nevertheless, in contrast to cation-exchanged zeolites, no lixiviation phenomenon was observed. The recycled catalyst was as active as a fresh sample and the selectivity to-wards fructose was unchanged. (Resume d'auteur)
TL;DR: In this article, heat-moisture treatment at the temperature of melting (T m ) and holding for 60 min in the calorimeter showed a slow digestibility compared to unheated samples.
Abstract: Non-waxy and waxy rice starches adjusted to 20% moisture (wet based, w.b.) were heated in a differential scanning calorimeter to determine the optimum parameters for producing slowly digestible starch (SDS). Starches heated to the temperature of melting (T m ) and held for 60 min in the calorimeter showed a slow digestibility compared to unheated samples. Digestibility decreased by 25 and 10%, respectively, for non-waxy and waxy rice starches relative to non-treated starches. Heat-moisture treatment of waxy corn, non-waxy corn and wheat starches at the T m determined for non-waxy rice starch did not result in significant decreases in digestibility. For waxy rice starches heat-treated in microwave or conventional ovens at the T m , there were slight but significant increases in digestibility of the treated starches compared to non-treated starches at all incubation times. Digestibility was higher for starches heated for 30 min than for 60 min. Non-waxy rice starches did not show any significant changes in digestibility. Heat-moisture treatment at the T m and the holding time of sample at that temperature in a differential scanning calorimeter were found to be significant to the formation of slowly digestible heat-moisture treated starch.
TL;DR: In this paper, the authors evaluated the possibility and efficiency of the grafting of acrylonitrile (AN) onto starch in presence of oxygen and observed a paradoxical action of oxygen.
Abstract: Monomer grafting, a unique technique for polysaccharide modification, is always performed under inert (e.g., N 2 ) atmosphere. This work is the first report related to evaluating the possibility and efficiency of the grafting of acrylonitrile (AN) onto starch in presence of oxygen. Thus, corn starch (in both granular and gelatinized states) as well as soluble starch were grafted by AN using a ceric-carbohydrate redox initiating system. Graft copolymerizations were performed under nitrogen, air, and oxygen atmospheres at similar conditions. Grafting occurrence was verified using chemical and spectral proofs. The polymerization mechanism and kinetics were investigated by recording the temperature variation of the exothermic reactions and by measuring grafting parameters. A paradoxical action of oxygen was observed. In spite of dictating a retardation period, molecular oxygen obviously favors efficient grafting of AN onto gelatinized starch. In case of soluble and granular starch, however, oxygen inhibits grafting under the same reaction conditions. Presence of DMF-insoluble fractions within the released polyacrylonitrile (PAN) side-chains, obtained from the starch-polyacrylonitrile (SPAN) products of reactions performed under O 2 and air, is attributed to some crosslinking reactions occurring during graft polymerization and/or acidic hydrolysis of the starch backbone of SPAN.
TL;DR: Univ Estadual Paulista, Dept Engn & Tecnol Alimentos, BR-15054000 Sao Jose do Rio Preto, SP, Brazil.
Abstract: Univ Estadual Paulista, Dept Engn & Tecnol Alimentos, BR-15054000 Sao Jose do Rio Preto, SP, Brazil
TL;DR: In this paper, the authors used the Brabender Viscoamylograph (VAG) and Rapid Visco Analyser (RVA) for evaluating the texture of cooked rice.
Abstract: Pasting properties of ten Thai rice varieties, with amylose contents in the range of 16 to 33% and stored at 10, 30 and 40 °C for six months were compared using the Brabender Viscoamylograph (VAG) and the Rapid Visco Analyser (RVA) for evaluating the texture of cooked rice. Linear correlations between pasting temperature and viscosity parameters based on RVA showed a different pattern than those based on VAG with high negative correlation coefficients between the peak and breakdown viscosities. Both RVA and VAG indicated peak viscosity to be positively correlated with breakdown viscosity, and negatively with the setback viscosity. Setback and consistency viscosities correlated with each other in both instruments but indicating a negative correlation with breakdown viscosity in VAG only. Pasting temperature determined by VAG and RVA did not show good correlations for rice sample stored at different temperatures neither for individual nor for combined data. Only peak, breakdown and setback viscosities showed significant correlations in the overall data (r > 0.496). The VAG measurements performed better than the RVA in the development of predictive models for evaluating the hardness and adhesiveness of cooked rice based on instrumental texture profile analysis. The springiness and cohesiveness of cooked rice could not be estimated from the pasting properties of rice flour determined by both VAG and RVA. Results showed that both VAG and RVA could be used for evaluating the texture of cooked rice despite the differences in the measurements of the pasting properties of milled rice flours.
TL;DR: A new sweet potato breeding line, Kanto 116, was developed, featuring low gelatinization temperature and an altered starch fine structure as mentioned in this paper, which showed an abnormal morphology characterized by cracking into granules.
Abstract: A new sweet potato breeding line, Kanto 116, was developed, featuring low gelatinization temperature and an altered starch fine structure. Starch granules from Kanto 116 showed an abnormal morphology characterized by cracking into granules. Starch content, amylose content and tuberous root appearance of Kanto 116 were similar to those of the control and the parents. Pasting temperatures of Kanto 116 starch determined by the Rapid Visco Analyser were 51.4 - 52.6 °C, approximately 20 °C lower than those of the control and parents starches. Onset, peak, and conclusion temperature of gelatinization, and gelatinization enthalpy of Kanto 116 starch determined by differential scanning calorimetry were 39.0 °C, 46.9 °C, 64.8 °C, and 8.8 J/g, respectively, and much lower than those of the control and parents starches. The chain-length distribution of the amylopectin molecules, determined by high-performance anion-exchange chromatography, showed that Kanto 116 starch had a higher proportion of short chains (DP 6 - 11) and a lower proportion of chains between DP 12 - 28 than control and parent starches. The debranched β-limit dextrin of Kanto 116 starch also showed that the proportion of both short and long B1 chains was different from those of the control and parents starches.
TL;DR: In many cases, membrane applications have increased quality of products, decreased energy costs and reduced disposal issues relating to waste treatment as discussed by the authors. But more work is needed regarding changes in nutrient quality when membranes are used in place of conventional separation technologies such as centrifugation, vacuum belt filtration and evaporation.
Abstract: The starch processing industry is characterized by streams that vary in diversity and complexity and that require extensive processing to achieve high end product quality. Water removal and product separations are two fundamental processing steps that impact product quality and processing economics. Many uses have been found for membrane technology in the starch processing industry; these include pretreatment of fresh water, recovery of solids and wastewater treatment. In many cases, membrane applications have increased quality of products, decreased energy costs and reduced disposal issues relating to waste treatment. Membranes can be used to filter many types of fluids in potato, wheat and corn starch isolation processes with varying degrees of success. Robust membrane materials have been developed with unique processing capabilities suited for the needs of the starch processing industry. Membranes have been used commercially to increase product quality while reducing costs, such as in syrup and sweetener clarification. Membrane technology has shown promise for reducing evaporation costs, improving product recovery and removing solids prior to wastewater treatment. In many applications, the cost of dewatering using membranes was a fraction of the cost of traditional methods. Membranes can be used to recover proteins from dilute process streams, but more work is needed regarding changes in nutrient quality when membranes are used in place of conventional separation technologies such as centrifugation, vacuum belt filtration and evaporation. There is need for detailed discussion of analyses regarding economics of long term operation and maintenance of membranes as part of a processing system.
TL;DR: In this article, three products (flour, starch and mucilage) were obtained form yam tubers and characterized by their chemical, structural, morphological, rheological and thermal properties.
Abstract: Aiming to find alternative uses of yam (Dioscorea alata) in the food industry, three products (flour, starch and mucilage) were obtained form yam tubers and characterized. Flours were obtained from peeled fresh tubers, dried at two different temperatures (30 and 55 °C) and then milled. Starch and mucilage were extracted from mashed yam before drying. Products were characterized by their chemical, structural, morphological, rheological and thermal properties. Flours showed differences in pasting, thermal and water absorption properties as a function of drying temperature. Starch contained 30% amylose. The analysis of monosaccharide composition of starch showed traces of mannose, xylose and rhamnose. The onset gelatinization temperature was 74.4 °C for starch, whereas those for flours varied between 71.5 and 74.4 °C. The relatively high gelatinization temperature and the absence of breakdown in the amylograph test evidenced the stable structure of starch when submitted to heat and shear. The mucilagenous material contained 55.36% protein and 43.05% starch, and also an acidic polysaccharide fraction linked to a neutral fraction. Flow curves of 1% mucilage dispersions showed a pseudoplastic behavior with high pH sensitivity. Results demonstrated that yam products have promising applications in the food industry.
TL;DR: In this paper, an anomalous role of oxygen was observed, i.e., oxygen may act simultaneously as an inhibitor, comonomer and indirect initiator, depending on the type of polysaccharide.
Abstract: Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric-carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N 2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi-empirical expressions and time-temperature profiles. An anomalous role of oxygen was observed, i.e., oxygen may act simultaneously as an inhibitor, comonomer and indirect initiator, depending on the type of polysaccharide. Measured grafting parameters, in most cases, showed a higher grafting yield and efficiency when the polymerization had been run under N 2 . However, medium to high grafting percentages were also achieved in air.
TL;DR: In this article, the suitability of porous starch as an adsorbent was tested, and it was found that porous starch was capable to adsorb a number of materials, i.e. liquids such as water, oils, and ethanol as well as gaseous flavor compounds.
Abstract: Rice starch was hydrolyzed by a mixture of glucoamylase and amylase to obtain porous starch as final product. The suitability of porous starch as an adsorbent was tested. It was found that porous starch was capable to adsorb a number of materials, i. e. liquids such as water, oils, and ethanol as well as gaseous flavor compounds. The adsorptive capacity of porous starch for coffee oil was saturated when contacting starch and coffee oil at 70 °C for 30 min, while the adsorbed coffee flavor could be released entirely when heating at 130 °C for 10 min. Compared with native starch, porous starch released the adsorbed coffee flavor more slowly: porous starch retained about 80% of coffee flavor when it was exposed to air at room temperature for 2 weeks.
TL;DR: In this article, the gelatinization transitions of the acid-modified tapioca starches were studied using Differential Scanning Calorimetry (DSC) and they showed that the increasing of the transition temperatures correspond to the retrogradation of the remaining partially hydrolyzed amylose followed by a decrease of these parameters corresponding to the reduction of the length of the chains of double helices amylopectin.
Abstract: Tapioca starch was partially hydrolyzed by 6% and 12% hydrochloric acid (w/v) at room temperature for various length of time. The gelatinization transitions of the acid-modified tapioca starches were studied using Differential Scanning Calorimetry. Starch suspensions (67% moisture) were heated at 5 °C/min to follow melting transition of amylopectin. As the hydrolysis time increased, onset (T o ), peak (T p ) and conclusion (T c ) temperatures of gelatinization have been observed to increase, in the same order of relative crystallinity, until reaching some critical values, then decreased with the large broadening of the endotherms. The increasing of the transition temperatures corresponded to the retrogradation of the remaining partially hydrolyzed amylose followed by a decrease of these parameters corresponding to the reduction of the length of the chains of double helices amylopectin.
TL;DR: In this article, a high pressure homogenizer was used to physically disrupt rice agglomerates in presence of water, followed by density-based separation, which yielded low-protein starch with starch damage of 5.3%, 99.9% and 2.7% protein in starch for nonwaxy starch.
Abstract: Starch-protein agglomerates of rice are physically disrupted in presence of water by use of a high pressure homogenizer called microfluidizer® followed by density based separation. Rice flour slurry at concentrations of 22, 32 and 36 % was passed twice through the microfluidizer to determine optimum concentration and recycling conditions. It was determined that 32 % slurry and two passes were optimum but the optimum pressure was 10.0 x 10 4 kPa for non-waxy rice flour and 6.2 x 10 4 kPa for waxy flour. These conditions yielded low-protein starch with starch damage of 5.3%, 99.9% particles with size less than 10 μm, starch recovery of 72% and 2.7% protein in starch for non-waxy starch. The same parameters were 6.1%, 99.0%, 76% and 3.3% for waxy starch. The peak, minimum, breakdown, final and setback viscosity was 237.8, 115.2, 122.6, 145.1, 29.9 and 68.2 RVU for low-protein waxy rice starch and 223.4, 140.2, 83.2, 258.6 and 118.4 RVU for non-waxy low-protein rice starch, respectively. The pasting temperature was 68.7 °C for waxy and 81.33 °C for non-waxy low-protein rice starch. The solubility of protein increased with increasing concentration and number of passes, however, it decreased with increasing number of passes for waxy rice protein.
TL;DR: This paper found that granule-associated proteins, including granule bound starch synthase (GBSS) and other granule proteins, were partially lost during alkaline extraction of rice starch, which may contribute to variations in paste properties of alkali-extracted starches.
Abstract: Starch granule-associated proteins, including granule-bound starch synthase (GBSS), were found to be partially lost during alkaline extraction of rice starch. Variability in amount of loss of GBSS and other granule proteins was found among different rice lines. Also, part of the GBSS and other granule proteins leached out during gelatinization of the alkali-extracted rice starch. Confocal laser scanning microscopy revealed that some protein still existed in gelatinized starch granules prepared from starch isolated using alkaline extraction. The starch that retained more GBSS and other granule proteins after alkaline extraction tended to have more protein in the isolated gelatinized starch granules, indicating that proteins resistant to alkaline extraction also tended to resist leaching during gelatinization. The study suggests that leaching of granule-associated proteins may contribute to variations in paste properties of alkali-extracted starches.
TL;DR: The physicochemical properties of high amylose rice flour prepared from wet milling and dry milling were examined and the rice vermicelli quality made from these flour samples was evaluated as discussed by the authors.
Abstract: The physicochemical properties of high amylose rice flour prepared from wet milling and dry milling were examined and the rice vermicelli quality made from these flour samples was evaluated. The effect of flour particle size on rice vermicelli quality was also determined. The milling method affected chemical compositions and all physicochemical properties of the flour. A higher degree of starch damage occurred in drymilled flour. Rice vermicelli made from dry-milled flour had higher cooking losses and softer texture than that made from wet-milled flour and the commercial reference products. Flour particle size influenced both cooking and textural quality of rice vermicelli but did not influence the water absorption index. Flours with larger particle sizes gave vermicelli with higher cooking loss and less desirable texture than flours with smaller particle sizes. Flour with particle sizes less than 200 mesh produced acceptable vermicelli in terms of cooking and textural quality.
TL;DR: In this paper, various methods for obtaining and purifying rice starch from white rice were examined and compared, and a combination of defatting and protein removal methods was shown to be useful in the purification of rice flour into starch and presented significant advantages over other reported methods.
Abstract: Various methods for obtaining and purifying rice starch from white rice were examined and compared. Processed starch was then debranched with isoamylase and the molecular weight distribution of the branches analysed by gel-permeation chromatography (GPC). The distribution of the chain lengths was compared between methods to quantify any damage sustained by the starch during purification. Effectiveness of protein removal was also determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A combination of defatting and protein removal methods was shown to be useful in the purification of rice flour into starch and presented significant advantages over other reported methods.
TL;DR: In this article, expansion and functional properties of corn starch extrudates were related to the weight average of the molecular weight (Mw) of extrudate molecules, the product temperature (PT), and the water content of the extruded mass.
Abstract: Expansion and functional properties of corn starch extrudates were related to the weight average of the molecular weight (Mw) of the extrudate molecules, the product temperature (PT), and the water content of the extruded mass Expansion of the extrudates was investigated by determining sectional, longitudinal and volumetric expansion indexes The expansion indexes of extrudates depended to various degrees on Mw'PT and water content of plasticised starch Taking into consideration that functional properties of extrudates are dependent both on the disintegration of the crystalline structure and the molecular degradation of the molecules of the starch granules, it was demonstrated that functional properties depend both on Mw and PT An increase in molecular degradation led to a decreasing cold paste viscosity (CPV) at constant PT The influence of the PT on the CPV was more pronounced at higher values of Mw than at lower ones Cold water solubility (CWS) of extrudates was dependent both on Mw and PT This dependency was similar to that of the CPV The sediment volume depended on Mw'PT and water content of the material on extrusion of the starch
TL;DR: In this paper, a novel method of preparing hydrophobic starch esters with a DS = 1.55-2.0 using amylose enriched starch (amylomaize starch) or potato starch and a fatty acid imidazolide in DMSO as solvent is described.
Abstract: A novel efficient method of preparing hydrophobic starch esters with a DS = 1.55-2.0 using amylose enriched starch (amylomaize starch) or potato starch and a fatty acid imidazolide in DMSO as solvent is described. The fatty acid imidazolides can be easily prepared by conversion of the corresponding acyl chloride with imidazole in toluene according to a synthesis route developed by Staab et al. [1-4]. The by-product imidazole hydrochloride could be converted to imidazole by alkaline work up with Na 2 CO 3 . As compared with the direct esterification of starch in presence of a fatty acid chloride the presented synthesis method does not need toxic amines like pyridine as catalyst. Only a catalytic amount of a methanolic KOCH 3 solution is required. Furthermore no hydrolytic degradation of starch could be observed in contrast to the direct esterification reaction with a fatty acid chloride.
TL;DR: In this paper, the retrogradation of amylopectin and its interaction with the surfactant sodium dodecyl sulphate (SDS) as a function of the exterior chain length (ECL) was investigated.
Abstract: The retrogradation of amylopectin and its interaction with the surfactant sodium dodecyl sulphate (SDS) as a function of the exterior chain length (ECL) of the amylopectin molecules was investigated. Amylopectin was modified by partial beta-amylolysis, which decreased ECL without causing any other changes in the molecular structure. Retrogradation of amylopectin was studied with differential scanning calorimetry (DSC), in the presence and absence of SDS. The retrogradation enthalpy of amylopectin was significantly dependent on the ECL, whereas the melting temperature was only to some extent influenced by ECL. The ability of SDS to inhibit the retrogradation of amylopectin depended on ECL, which suggests that there was a specific binding of SIDS to amylopectin, The decrease in retrogradation when SDS was added to the amylopectin sample was less when ECL decreased. The overall effect was thus an increase in retrogradation in the presence of SIDS when the ECL decreased, Small changes in the molecular structure of amylopectin gave rise to sharp changes in both retrogradation and interaction with lipids, showing that the molecular structure is important for the crystallisation and interaction behaviour of amylopectin.
TL;DR: In this paper, potato starch granules were partially hydrolysed to produce maltodextrins with dextrose equivalents (DE 10, 15 and 20) and films were prepared by water casting.
Abstract: Native and freeze-dried potato starch granules were partially hydrolysed to produce maltodextrins with dextrose equivalents (DE) 10, 15 and 20. Freeze-drying greatly improved the enzyme accessibility of the native granules. Film formation properties of the hydrolysates were examined. Films were prepared by water casting. Especially the maltodextrins, which were produced from the native starch, were very sticky materials and could not form any films. But after removing most of the soluble saccharides from the maltodextrins, good quality films were produced by dissolving the hydrolysate in water, casting on a Teflon mould and drying the solution.
TL;DR: In this article, six types of anionic starch derivatives, viz. carboxymethyl starch, carboxyethyl starch and poly(acrylic acid)-starch graft copolymer, were prepared and evaluated as flocculants.
Abstract: Six types of anionic starch derivatives, viz. carboxymethyl starch, carboxyethyl starch, poly(acrylic acid)-starch graft copolymer, starch-2-hydroxypropylcitrate, starch-2-hydroxypropylphosphate and starch-2-hydroxypropylsulfate, were prepared and evaluated as flocculants. The flocculation efficiency was monitored via estimation of the optimal dose, transmission % and weight removal %. The different factors affecting the flocculation were studied. These factors include the type of acidic group, the length of the chain bearing the acidic group, the chemical formula and molar mass of the flocculant, the acid content and the pH. The flocculation efficiency of various anionic starches depends on (a) the acidic group type and follows the order: sulfate > phosphate > carboxyl; (b) the length of the alkyl chain bearing the carboxyl group in the order: starch-2-hydroxypropylcitrate > carboxyethyl starch > carboxymethyl starch; (c) the chemical formula which indicate that the flocculants prepared via grafting have a higher flocculation efficiency than those prepared by etherification. The flocculation efficiency increases with increasing the acid content and/or decreasing the molar mass of the flocculant. Flocculation efficiency at pH 8 is higher than tat pH 6.