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1.
Composition and properties of seeds and starches from five Virginia‐grown kabuli chickpea cultivars were investigated. The seeds had the average weight of 4.48 g per 10 g and volume of 641.2 mm3, and were rich in carbohydrate with starch as a principal constituent (59.2–70.9%). Resistant starch accounted for 7.7–10.4% of the total starch content. The composition and properties of the starches among the five cultivars were significantly different (≤ 0.05). All starches had a C‐type crystalline structure. The degree of crystallinity ranged from 21.1% to 27.4%, gelatinisation temperature from 7.97 to 11.2 °C and gelatinisation enthalpies from 2.18 to 3.76 J g?1, and water absorption capacities from 90.7% to 117.5%. Different shapes and granule sizes were observed. Molecular weight of amylopectin was in the range of 6.35 × 108–11.6 × 108 Da. Cultivar ‘HB‐14’ was superior to the other cultivars, when combining larger seed size, higher resistant starch level and better properties.  相似文献   

2.
This study was performed to evaluate the effect of partial gelatinisation on the retrogradation of modified potato starch. The partially gelatinised starches with gelatinisation degree at mean levels of 22.47%, 49.18%, 76.80% and 86.19% were prepared by ball milling (0.5, 1.5, 3 and 10 h). The thermal properties and crystal structure of retrograded starch were examined during 21 days of refrigerated storage at 4 °C. Retrograded starch with high initial gelatinisation degree (86.19%) showed higher retrogradation enthalpy of 6.12 ± 0.18 J g?1 and lower onset temperature of 45.41 ± 0.24 °C than sample with low gelatinisation degree (22.47%) where the results were 1.32 ± 0.18 J g?1 and 54.05 ± 0.03 °C, respectively. During storage, two peaks in the X‐ray diffractograms for starch with high gelatinisation degree appeared and increased rapidly, while the peaks for starch with low gelatinisation degree increased slowly. These results suggest that a certain amount of remainder crystals presented in partially gelatinised starch impeded the retrogradation.  相似文献   

3.
The starches separated from bulbs of four different lily cultivars (Lanzhou, Pinglu, Yixing‐1, and Yixing‐2) were investigated for physicochemical, morphological, crystalline, and thermal properties. AM content of lily bulbs starches from different cultivars ranged from 19.46 to 25.17%. The swelling power of starches ranged between 14.4 and 21.3 g/g, and the solubility ranged from 8.92 and 16.6% at the temperature of 85°C. Four cultivars of lily starches paste had excellent transparency and the transmittance value of Lanzhou lily as high as 54.7%. The transmittance of the gelatinized aqueous starch suspensions, from all lily cultivars, decreased with increase in storage period. The shape of starch granules varied from triangular to cylindrical and XRD of four lily starches all showed B‐type pattern. The transition temperatures and enthalpy of gelatinization (ΔHgel) were determined using DSC. Tp varied from 62.52 to 65.25°C. Pinglu lily starch showed the highest ΔHgel and gelatinization range (TcTo) index among starches from four different lily cultivars.  相似文献   

4.
Granule sizes, macromolecular features and thermal and pasting properties of starches from seven tropical sources (Florido, Kponan and Esculenta yams, cocoyam, cassava, sweet potato and ginger) were compared with those of several well‐known cereal, legume and tuber starches. The aim of the study was to characterise some non‐conventional starches with a view to possibly marketing them. Amylose content varied from 148 mg g?1 in Esculenta starch to 354 mg g?1 in smooth pea starch. For total starches, weight‐average molar mass (M?w) ranged between 0.94 × 108 and 1.80 × 108 g mol?1 for potato and normal maize starches respectively. Gyration radius (R?G) varied from 157 nm for ginger starch to 209 nm for normal maize starch. Gelatinisation enthalpy (ΔH) ranged between 9.8 and 20.7 J g?1 for wheat and Florido starches respectively. Gelatinisation peak temperature (Tg) varied from 58.1 °C for wheat starch to 87.3 °C for ginger starch. Native starch granule mean diameter ranged between 5.1 and 44.5 µm for Esculenta and potato starches respectively. Cassava and potato starches had the highest swelling power and dispersed volume fraction at all treatment temperatures, while ginger starch had the lowest. Cocoyam starch had the highest and ginger starch the lowest solubility at 85 and 95 °C. Cassava starch was the most stable under cold storage conditions. Roots and tubers such as ginger and cassava produced in the Ivory Coast are new sources of starches with very interesting properties. Thus these starches could be isolated on an industrial level in order to market them. Copyright © 2007 Society of Chemical Industry  相似文献   

5.
Endosperm starch isolated from an amylose‐free waxy mutant hull‐less barley line, Shikoku Hadaka 97, had an amylose content of 0.3% and higher swelling power than ordinary waxy barley cultivars/lines with amylose contents of 2.2—6.5%. A highly significant correlation was observed between amylose content and swelling power among waxy barley starches. No clear differences were detected in the chain‐length distribution profiles or thermal properties between the amylose‐free starch and ordinary waxy starch. The chain‐length distribution profile of waxy barley starch was slightly different from that of normal barley starch. Gelatinization temperatures and gelatinization enthalpy of waxy barley starch were higher than those of normal barley starch. Significant correlations were observed between amylose content and thermal properties of starch samples analyzed. Waxy barley starch stained with a concentrated iodine‐potassium iodide solution showed a ghost‐like appearance.  相似文献   

6.
Starch samples from ten mung bean cultivars grown in china were isolated, and their morphology, physicochemical, thermal, and pasting properties were evaluated. The objectives of the study were to investigate the starch properties and processing characteristics of different mung bean varieties, and to establish the basic foundation of improving the functionality of mung beans and their starch grown in the region. The mung bean starches showed the kidney-shaped, elliptical, small spherical and dome-shaped granules, and the starches granule size varied between 5 and 40 μm. Total starch content, amylose content, solubility, and swelling power ranged from 54.73% to 57.99%, 40.44% to 41.82%, 13.72% to 17.67%, and 17.27% to 20.55%, respectively. The pasting properties were determined using a rapid visco analyzer, and various mung bean starches exhibited different pasting profiles. Different starches differed in transition temperatures (T o, T p, and T c), gelatinization temperature range (ΔT r), and enthalpy of gelatinization (ΔH) according to differential scanning calorimeter analysis. Hydration coefficient, degree of gelatinization, and hardness of mung bean varieties ranged from 51.97% to 84.46%, 62.99% to 95.11%, and 26.07 N to 112.11 N, respectively. This study indicated that starches separated from different mung bean cultivars possess different physicochemical characteristics, and various mung beans cultivars showed diverse processing properties.  相似文献   

7.
Thermodynamic characteristics defining gelatinisation (modelled as ‘melting’) processes for starches extracted from two sweet potato cultivars (Ayamurasaki and Sunnyred) grown in soil at different temperatures (15, 21, 27 or 33 °C) were studied using high sensitivity differential scanning calorimetry (DSC). The gelatinisation temperatures for all starches were elevated significantly with increasing growth temperature. A linear correlation between growth temperature and gelatinisation temperature of extracted starches was found for both cultivars. The increase of gelatinisation temperatures was associated with almost constant or slightly increased enthalpy (Ayamurasaki) but with moderate elevation of crystalline lamellae thickness (Sunnyred). Elevation of gelatinisation temperatures by 8‐9 °C by DSC for starches heated in 1.5 M aqueous KCl were found in comparison with aqueous starch dispersions. The crystalline polymorphic form was confirmed as A‐type using wide angle X‐ray scattering (WAXS). The values of the thermodynamic surface parameters characterising the faces of crystalline lamellae of these starches were calculated. Two endothermic peaks were observed by DSC for starches grown at 15 °C when suspended in 1.5 M KCl solution. The first peak was ascribed to the melting of B‐type structure while the second one was attributed to the melting of A‐type structure. As a conclusion it was suggested that these starches contain C‐type polymorphic structures.  相似文献   

8.
Starches were isolated and characterised from 10 potato cultivars grown under the same conditions (with a commercial starch for reference). The chemical composition revealed some differences amongst the starches with protein ranging from 0.30% to 0.34%, amylose 25.2% to 29.1% and phosphorus 52.6–66.2 mg 100 g−1. High performance size-exclusion chromatography (HPSEC) fractionation of isoamylase debranched amylopectin showed that the amylopectin molecules were less branched and consisted of more B1, but less A-chains, than cereal starches. Gelatinisation onset (To), peak (Tp) and conclusion (Tc) temperatures of the native potato starches ranged from 58.7 to 62.5 °C, 62.5 to 66.1 °C and 68.7 to 72.3 °C, respectively, whilst the gelatinisation enthalpies ranged from 15.1 to 18.4 J g−1. The gelatinisation temperatures of the starches increased in common with the amounts of short and intermediate sized amylopectin chains. The 13C magic angle spinning nuclear magnetic resonance (13C CP-MAS NMR) and wide angle X-ray diffraction (XRD) data (30.6% ± 0.22% crystallinity on average) showed little variance amongst the samples. Particle sizing results, however, revealed more variance (20.6–30.9 μm mean diameter). Overall, these data reveal the subtleties of cultivar specific variation against a background of constant environmental conditions.  相似文献   

9.
Starches separated from different potato cultivars were modified using two different cross‐linking agents: epichlorohydrin (EPI) and phosphoryl chloride (POCl3) at different concentrations (1.0 and 2.0 g kg?1 POCl3; 2.5, 5.0 and 10 g kg?1 EPI). Differential scanning calorimetry, rheological and retrogradation measurements were performed to characterise the influence of cross‐linking on the properties of potato starches. Cross‐linking considerably reduced swelling power, solubility, water‐binding capacity and paste clarity. The decrease became greater as the reagent concentration increased. The starches treated with 1.0 g kg?1 POCl3 exhibited exceptionally higher swelling power than their counterpart native starches. Neither cross‐linking agent caused any change in morphology of the starch granules. Studies on the phase transitions associated with the gelatinisation showed significantly higher values for the onset temperature (To), peak temperature (Tp), conclusion temperature (Tc) and enthalpy of gelatinisation (ΔHgel) for the cross‐linked starches than the native starches. Starches treated with both the reagents showed lower peak storage modulus (G′) and loss modulus (G″) than their native counterparts. The tendency of the starch pastes towards retrogradation increased considerably with increases in storage duration. However, the starches treated with 1 g kg?1 POCl3 exhibited much lower syneresis than the other cross‐linked starches. Copyright © 2006 Society of Chemical Industry  相似文献   

10.
The physicochemical properties of small, medium and large starch granules separated from four potato cultivars were investigated to reveal whether functional properties differed among the various size classes of the starches. Large‐size fractions showed higher amylose content and light transmittance and lower swelling power than small‐size fractions. The granules from the three fractions had diameters of 5–20, 25–40 and 40–85 µm respectively. The large and medium granules were ellipsoidal to irregular or cuboidal while the small granules were spherical or ellipsoidal in shape. The transition temperatures and gelatinisation temperature range of the fractionated starches increased while the enthalpy of gelatinisation decreased with decreasing granule size. Rheological parameters such as peak storage (G′) and loss (G″) moduli increased in the order small‐, medium‐ and large‐granule starches when subjected to temperature sweep testing. The breakdown in peak G′ during the heating cycle and retrogradation during storage were found to be highest for large‐ and lowest for small‐size fractions. The differences in functional properties among the different size fractions suggested that the granule size distribution is an important parameter that can influence the behaviour of potato starch during processing. Copyright © 2004 Society of Chemical Industry  相似文献   

11.
This study investigated the effects of heat‐moisture treatment (HMT) on the resistant starch content and thermal, morphological, and textural properties of rice starches with high‐, medium‐ and low‐amylose content. The starches were adjusted to 15, 20 and 25% moisture levels and heated at 110°C for 1 h. The HMT increased the resistant starch content in all of the rice starches. HMT increased the onset temperature and the gelatinisation temperature range (Tfinish–Tonset) and decreased the enthalpy of gelatinisation of rice starches with different amylose contents. This reduction increased with the increase in the moisture content of HMT. The morphology of rice starch granules was altered with the HMT; the granules presented more agglomerated surface. The HMT affected the textural parameters of rice starches; the high‐ and low‐amylose rice starches subjected to 15 and 20% HMT possessed higher gel hardness.  相似文献   

12.
Flours processed from three black gram cultivars (Mash1‐1, PU‐19 and T‐9) were studied for proximate composition, physicochemical and functional properties. Protein, fat, ash and crude fibre content varied significantly (P ≤ 0.05) from 24.5 – 28.4%, 1.1–1.4%, 2.7–3.3% and 2.7–3.4%, respectively, among the cultivars. Significant differences were also observed in other physicochemical properties. Pasting properties like peak viscosity, breakdown viscosity and setback viscosity were in the range of 2078.7–2473.0 cP, 644.0–863.7 cP and 588.3–804.0 cP, respectively. Textural profile analysis of flour gels displayed significant differences in hardness (13.0–18.9 g), gumminess (2.8–5.9 g), chewiness (2.0–5.7 g) and adhesiveness (21.0–40.9 g). Differential scanning calorimetry revealed starch gelatinisation from 63.5 to 75.6 °C and amylose lipid complex melting from 105.0 to 136.1 °C. Protein solubility profile in the pH range of 2–9 varied from 6.3 to 97.3%. Emulsifying activity index and Emulsifying stability index at pH 3, 5 and 7 varied correspondingly from 6.0 to 14.5 m2 g?1 and 18.8 to 64.9 min. Foaming capacity of 2% flour suspensions at pH 2, 4, 6, 8 and 10 varied significantly from 67.3 to 130% among the cultivars. Foam stability varied at different pH and was observed between 0 and 70.8% among the cultivars.  相似文献   

13.
Commercial maize starches and potato starches of two cultivars differing in physicochemical composition (granule size distribution; amylose to amylopectin ratio) and crystallinity were heated to 180 °C and then cooled by fast quench using a differential scanning calorimeter (DSC), in order to produce spherulitic starch morphologies. Among the raw maize starches, waxy maize starch had highest relative crystallinity (49%) whereas a lowest crystallinity of 33–39% was calculated for high-amylose maize starches. Potato starches showed a relative crystallinity of 50%. The temperatures and enthalpies of gelatinisation and melting varied among all the starches. High-amylose maize starches showed higher transition temperatures of gelatinisation (Tgel), whereas waxy maize starch had lowest Tgel and enthalpy of gelatinisation (ΔHgel). Similarly, a considerable variation in parameters related with crystalline melting (Tm1, Tm2 and ΔHm1, ΔHm2) was observed for different starches. The superheated gels of different starches treated using DSC were subjected to polarised microscopy, to confirm the formation of spherulites. Both the high-amylose starch gels showed the presence of spherulites exhibiting birefringence and a weak crystalline pattern. No birefringence was observed for waxy maize starch gel, while potato starch gels had some birefringence. The particle size distribution of high-amylose maize starch gels analysed through Zetasizer showed the sizes of spherulitic particles fall in the range of 300 nm–900 nm. The scanning electron micrographs of the dried high-amylose maize starch gels showed the presence of round spherulites consisting of several aggregated spherulitic particles. Amylose content and melting of crystallites during heating play an important role during recrystallisation of amylose (spherulite morphologies).  相似文献   

14.
This research aimed to study physicochemical properties and in vitro digestibility of flours and starches from taro cultivated in different regions of Thailand, that is, Kanchanaburi (KB), Chiang Mai (CM), Phetchaburi (PB) and Saraburi (SB). Taro starches were extracted from taro flours using either water or alkaline extraction. The taro flours had significantly (P ≤ 0.05) larger particle size, higher pasting and gelatinisation temperatures, and resistant starch content but lower total starch content, whiteness (L* value), paste viscosities and clarity than their corresponding extracted starches. All the taro starches exhibited polygonal and irregular granules and gave A-type X-ray diffraction pattern. The alkaline-extracted taro starches had significantly (P ≤ 0.05) higher extraction yield, total starch content, L* value, pasting and gelatinisation temperatures, and paste clarity but lower granular size, amylose content, resistant starch content, paste viscosities and relative crystallinity than their water-extracted counterparts.  相似文献   

15.
BACKGROUND: The aim of this study was to determine the physicochemical properties of starches isolated from Malawian cocoyams and compare them with those of cassava and corn starches. RESULTS: The purity of the isolated starches varied from 851 to 947 g kg?1 and pH from 4.93 to 6.95. Moisture, ash, protein, fat and amylose contents ranged from 104 to 132, 0.3 to 1.5, 3.5 to 8.4, 0.9 to 1.6, and 111 to 237 g kg?1, respectively. Cocoyam starches gave higher potassium and phosphorus but lower calcium levels than the other starches. The shape of starch granules varied from spherical to polygonal with cocoyam starches displaying smaller‐sized granules than cassava and corn starches. Cocoyam starches gave a higher wavelength of maximum iodine absorption and blue value but lower reducing capacity values than cassava and corn starches. The extent of acid hydrolysis of the starches also differed. Cocoyam starches exhibited amylopectin molecules of higher molecular weights but amylose molecules of lower molecular weights than cassava and corn starches. Cocoyam starches exhibited lower water absorption capacity and swelling power, paste clarity and viscosity but higher solubility, gelatinisation temperatures and retrogradation tendencies than cassava and corn starches. CONCLUSIONS: The physicochemical properties of native Malawian cocoyam starches vary among the different accessions and differ from those of cassava and corn starches. Copyright © 2010 Society of Chemical Industry  相似文献   

16.
The effect of heat‐moisture treatment (HMT) on the properties of pinhão starches under different moisture and heat conditions was investigated. The starches were adjusted to 15, 20 and 25% moisture levels and heated to 100, 110 and 120°C for 1 h. The X‐ray diffractograms, swelling power, solubility, gel hardness, pasting properties and thermal properties of the native and HMT pinhão starches were evaluated. Compared to native starch, there was an increase in the X‐ray intensity and gel hardness of HMT starches, with the exception of the 25% moisture‐treated and 120°C heat‐treated starch. HMT reduced the swelling power and solubility of the pinhão starches when compared to native starch. There was an increase in the pasting temperature, final viscosity and setback and a decrease in the peak viscosity and breakdown of HMT pinhão starches compared to native starch. HMT increases the gelatinisation temperature of native pinhão starch and reduces gelatinisation enthalpy.  相似文献   

17.
The degradation of barley and pea fibres along the gastrointestinal tract (GIT) of pigs and its relation to changes in some of their physicochemical properties were investigated. Ileal and caecal digesta containing pea cotyledon fibre showed the highest (P < 0.05) swelling (33.1–36.7 ml g?1 DM) and water retention capacity measured by centrifugation (17.9–21.2 g g?1 DM) and by osmotic pressure (9.0–9.1 g g?1 DM). The particle size of barley hull did not change along the GIT (160–207 µm), whereas that of pea cotyledon and pea hull was drastically reduced in faeces (62–65 µm) compared with the ileum and caecum (198–415 µm). The digestibility of non‐starch polysaccharides (NSP) was lowest for barley hull in the ileum (5% of intake), caecum (0% of intake) and faeces (26% of intake). The digestibility of NSP was highest for pea cotyledon fibre and dehulled barley in the proximal hindgut and for pea cotyledon fibre in faeces (96% of intake for pea cotyledon vs 74–82% of intake for dehulled barley and pea hull). In conclusion, hydration properties and particle size add valuable information when describing the fermentation of fibres in the GIT. However, they cannot be used alone as indicators of the extent of fermentation of different fibres. The results also suggested that the fibre source and the organisation and lignification of the cell walls lead to different fermentation processes along the GIT of pigs. © 2001 Society of Chemical Industry  相似文献   

18.
A new starch was isolated from fruits of two acorn species, Quercus rotundifolia and Quercus suber by alkaline (A3S) and enzymatic (ENZ) methods and physical and functional properties were studied. The isolation method induced changes in most of those properties in the isolated starches, mainly in resistant starch content, syneresis, pasting, thermal and rheological properties. Isolated acorn starches presented high amylose content (53–59%) and resistant starch content (30.8–41.4%). Acorn starches showed limited and similar solubility values and swelling power values, showing a gradual increase from 60 °C to 90 °C. The pasting temperatures ranged from 67.5 to 72.0 °C and pastes did not present breakdown, which is suggestive of a high paste stability of acorn starches during heating. At ambient temperature the turbidity and syneresis values were low, but when held at freezing temperatures the syneresis significantly increased. Thermal analysis revealed that the acorn starches easily undergo transition phenomena as shown by the low To and enthalpy values (4.1–4.3 J/g), these effects were more evident in starches isolated by ENZ method. Pastes are more elastic than viscous and form strong gels after cooling. Q. suber starch was shown to be more sensitive to the effect of isolation method. Generally, starch isolated by enzymatic method presented less interesting functional properties, since this isolation procedure greater affected the raw structure of starches.  相似文献   

19.
The starches separated from thirteen different black gram cultivars were investigated for physicochemical, thermal, morphological and pasting properties. Amylose content, swelling power, solubility and water binding capacity of starches ranged between 30.2–34.6%, 16.0–22.3 g/g, 14.8–17.3% and 73.5–84.5%, respectively. The diameter of starch granules, measured using a laser‐light scattering particle‐size analyzer, varied from 12.8 to 14.3 μm in all black gram starches. The shape of starch granules varied from oval to elliptical. The transition temperatures (To, Tp and Tc) and enthalpy of gelatinization (ΔHgel) determined using differential scanning calorimetry, ranged between 66.1–71.3, 71.0–76.2, 75.9–80.4°C and 6.7–9.4 J/g, respectively. Pasting properties of starches measured using the Rapid Visco Analyser (RVA) also differed significantly. Pasting temperature, peak viscosity, trough, breakdown, final viscosity and setback were between 75.8–80.3°C, 422–514, 180–311, 134–212, 400–439 and 102–151 Rapid Visco Units (RVU), respectively. Turbidity values of gelatinized starch pastes increased during refrigerated storage. The relationships between different properties were also determined using Pearson correlation coefficients. Amylose content showed a positive correlation with swelling power, turbidity and granule diameter. Swelling power showed a negative correlation with solubility and setback. To, Tp and Tc showed positive correlation with turbidity, pasting temperature and were negatively correlated to peak and breakdown viscosity.  相似文献   

20.
Structure‐function relationship of rice starch is scarce in the literature. Starch was isolated from diverse Mexican rice varieties and their swelling power (SP), soluble solids (ss), thermal and pasting properties, XRD pattern, in vitro starch digestibility, and AP chain‐length distribution were evaluated. Rice starches with low SP at 60°C had higher temperature and enthalpy of gelatinization. The peak viscosity of rice starches ranged between 2426 and 3519 cP, and the samples presented high values for setback due to the AM content. Rice starches presented the typical A‐type XRD pattern with crystallinity values between 32.7 and 36.3%. Rice starches presented high amounts of short chains (A and B1), and differences were found among the cultivars. AM content for rice starches ranged between 18.4 and 22.9%, and the main fraction recorded by HPSEC was the Fraction III (short chains) with values around 60%. The uncooked rice starch samples presented high values of slowly digestible starch (SDS) and rapidly digestible starch (RDS), and differences were found among the cultivars. In cooked samples decreased SDS and increased RDS and RS. Onset temperature and enthalpy of gelatinization were correlated with the percentage of A‐chains and an opposite pattern was found with the percentage of B1 chains. AP structural characteristics affect the functional, physicochemical, and digestibility properties of rice starches.  相似文献   

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