Corn, rice, wheat and potato are the main sources of starches which differ significantly in compo... more Corn, rice, wheat and potato are the main sources of starches which differ significantly in composition, morphology, thermal, rheological and retrogradation properties. Cereal starches contain a significant quantity of phospholipids, while potato starch is rich in esterified phosphorus. Potato starch exhibits higher swelling power, solubility, paste clarity and viscosity than wheat, rice or corn starches. Morphological characteristics, such as shape and size of the starch granules, exhibit significant differences. Potato starch granules are smooth–surfaced, oval and irregular or cuboidal-shaped while corn, rice and wheat starch granules are angular, pentagonal and angular; and spherical and lenticular–shaped, respectively. Corn, rice and wheat starch granules are less smooth–surfaced than potato starch granules. Potato starch granules are largest (<110 μm) in size followed by wheat (<30 μm), corn (<25 μm) and rice (<20μm) starches. Gelatinization temperatures (To, Tp, Tc) and enthalpies of gelatinization (ΔHgel) of starches from different sources also differ significantly. Corn and rice starches generally show higher transition temperatures than wheat and potato starches while the ΔHgel values are higher for potato and wheat starches. Potato starch shows a higher tendency towards retrogradation than the cereal starches. The rheological properties, such as storage modulus (G′) and loss modulus (G″) of the starches from the different sources increase to a maximum and then drop during heating of all the starches. Potato starch shows highest peak G′, G″ and lower tan δ than corn, rice and wheat starches during the heating cycle.
Corn starch and starches separated from different potato cultivars were acetylated to evaluate th... more Corn starch and starches separated from different potato cultivars were acetylated to evaluate the effect of plant source on the physicochemical, morphological, thermal, rheological, textural and retrogradation properties of the starches. Corn starch showed a lower degree of acetylation than potato starches under similar experimental conditions. The degree of acetylation for different potato starches also differed significantly. Morphological examination revealed that the granules of acetylated Kufri Chandermukhi and Kufri Sindhuri starches tended to appear as fused and less smooth than native starch granules. Acetylation of corn and potato starches decreased the transition temperatures and enthalpy of gelatinization and increased swelling power and light transmittance. However, the change in these was greater in the potato starches with higher percentage of small sized granules. Acetylated starches showed higher peak G',G'' and lower tan δ than their counterpart native starches during heating. Among the starches from different cultivars, the change in the rheological parameters after acetylation differed to a significant extent. The retrogradation was observed to be negligible in the acetylated cooked starch pastes. Results implied that the change in functional properties of starches with acetylation depends on source and granule morphology of native starch.
Granulated cold water soluble (GCWS) starches were prepared from corn starch and starches separat... more Granulated cold water soluble (GCWS) starches were prepared from corn starch and starches separated from four potato cultivars using alcoholic-alkaline method. The morphological, thermal and rheological properties of GCWS corn and potato starches were studied. The amylose content of the GCWS starches from corn and potato starches were significantly lower as compared to their counterparts native starches. GCWS potato starches showed higher cold water solubility than GCWS corn starch. Cold water solubility of GCWS starches prepared from different potato cultivars also differed significantly. Native potato starch granules were larger in size (15–45 μm), smooth, oval and irregular or cuboidal shaped while native corn starch granules were smaller in size (5–18 μm), less smooth, rounded and angular shaped. Both corn and potato starches were distorted and indented during conversion to GCWS starches, however, this effect was more pronounced in potato starches than corn starch. The extent of distortion in GCWS starches differed significantly in starches prepared from different potato cultivars. The potato cultivars having starch with large sized granules showed more granular distortion as compared in those having small sized granules during GCWS starch production. Native corn starch showed higher transition temperatures and lower enthalpy of gelatinization (ΔHgel) than native potato starches. GCWS corn and potato starches did not show any gelatinization endotherm during heating between 20 and 100 °C. The rheological properties such as G′, G″, η′ and of GCWS corn and potato starches also showed significant variation, when subjected to frequency sweep testing. GCWS potato starches showed higher G′, G″, η′ and lower than GCWS corn starch. The G′, G″, η′ of the GCWS starches from both corn and potato increased and decreased with the increase in temperature. The turbidity of GCWS and native corn and potato starches increased during storage at 4 °C, however, the increase was less pronounced in GCWS starches.
Effects of fatty acids (myristic and stearic acid) on the rheological properties of corn and pota... more Effects of fatty acids (myristic and stearic acid) on the rheological properties of corn and potato starch during heating and cooling were investigated using a Carri-Med CSL2 dynamic rheometer. Potato starch showed a lower gelatinization temperature (TG′) as compared to corn starch. Potato starch had a TG′ of 61.2°C against 71.5°C for corn starch. The addition of both the fatty acids inhibited the swelling of the starch granules in both corn and potato starch and consequently, increased the TG′. The storage modulus (G′) increased to a maximum and then dropped during heating of both the starches. Potato starch showed a higher peak G′ value as compared to corn starch. Addition of stearic acid decreased the peak G′ in corn starch and increased the same in potato starch, while the addition of myristic acid resulted in a decrease in peak G′ in both the starches. The extent of breakdown in G′ during heating was higher for potato starch as compared to corn starch which confirmed the more rigid structure of corn starch granules. During cooling, the G′ values increased with decrease in temperature and with the addition of fatty acids. Corn starch showed higher peak loss tangent (tan δ) values than potato starch during heating. Tan δ values decreased during the cooling of corn and potato starch. Retrogradation (synersis) behaviour of both the starches heated in the presence of stearic and myristic acid during storage was also studied. The rate of synersis was more in potato starch than in corn starch. Synersis increased with the increase in storage duration and decreased with the addition of both the fatty acids.
The starches separated from five different Indian potato cultivars (Kufri Chandermukhi, Kufri Bad... more The starches separated from five different Indian potato cultivars (Kufri Chandermukhi, Kufri Badshah, Kufri Jyoti, Kufri Sindhuri and S1) were investigated for morphological, thermal, rheological, turbidity and water-binding properties. The starch separated from all the five potato cultivars had a granule size ranging between 15–20 μm and 20–45 μm. The shape of starch granules varied from oval to irregular or cuboidal. Starch isolated from cv. Kufri Badshah had largest irregular or cubiodal granules while starch from cv. Kufri Chandermukhi had small and oval granules. The transition temperatures and enthalpy of gelatinization (ΔHgel) were determined using differential scanning calorimetry (DSC). The enthalpy of retrogradation (ΔHret) of gelatinized starch was also determined after 14 days of storage at 4°C using DSC. Kufri Chandermukhi starch showed the lowest ΔHgel and ΔHret while Kufri Badshah starch showed the highest values. ΔHgel and ΔHret values of 12.55 J/g and 6.42J/g, respectively, for Kufri Chandermukhi starch against 13.85 J/g and 8.61 J/g, respectively, for Kufri Bhadshah starch were observed. Rheological properties of starches from different potato cultivars, measured using the Dynamic Rheometer during heating and cooling, also differed significantly. The starch from cv. Kufri Badshah showed the highest peak G′ and G″ and lowest tan δ. The starches having higher peak G′(G′ at gelatinization temperature) showed higher breakdown in G′ and vice versa. The turbidity of gelatinized aqueous starch suspensions from all potato cultivars increased with increase in storage period. Starches with low water binding capacity had higher G′ and G″ and lower tan δ values.
Effect of some common chemical modifications such as acetylation, hydroxypropylation and cross-li... more Effect of some common chemical modifications such as acetylation, hydroxypropylation and cross-linking on the physico-chemical, morphological, thermal and rheological properties of starches from different botanical sources have been reviewed. The distinguishing factors that affect the efficiency of modification are the starch source, amylose to amylopectin ratio, granule morphology, and type and concentration of the modifying reagent. The extent of alteration in the starch properties reflects the resistance or the susceptibility of a starch towards different chemical modifications. Modified starches with desirable properties and degree of substitution can be prepared by critically selecting a suitable modifying agent and a native starch source.
Starches separated from four potato cultivars were hydroxypropylated and their physico-chemical, ... more Starches separated from four potato cultivars were hydroxypropylated and their physico-chemical, morphological, thermal and rheological properties were compared. The extent of hydroxypropylation measured as molar substitution differed significantly among the starches from different potato cultivars. Kufri Jyoti hydroxypropylated starch showed highest molar substitution, while Kufri Chandermukhi hydroxypropylated starch showed the lowest. The hydroxypropylated starches showed higher swelling power, solubility, solubility in dimethyl sulphoxide (DMSO) and paste clarity than their counterpart native starches. Light transmittance of hydroxypropylated starches did not change significantly during refrigerated storage while a substantial decrease in the same was observed for native starches. SEM pictures showed that the hydroxypropylated starch granules from all the potato cultivars differed in shape and size from the native starch granules, and showed the presence of slight fragmentation and a distinct groove in their central core region along the longitudinal axis. Hydroxypropylation treatment showed more pronounced effect on large size granules than small size granules. The extent of granule disruption was observed to be higher for hydroxypropylated starch gels that later developed numerous rod shaped or fuzzy clustered microfibrils with diameters ranging from 15 to 20 μm, after 30 days of refrigerated storage. The studies on the phase transitions associated with gelatinization of starches showed lower gelatinization parameters (To, Tp, Tc, and ΔHgel) among the hydroxypropylated starches in which Kufri Jyoti and Kufri Sindhuri starches were the most affected. Hydroxypropylated potato starches exhibited higher peak G′, G″ and lower during rheological measurements on the dynamic rheometer. Whereas the native starches did not possess freeze-thaw stability, upon hydroxypropylation there was a pronounced decrease in the tendency towards syneresis.
The physicochemical, morphological, thermal and rheological properties of acetylated corn and pot... more The physicochemical, morphological, thermal and rheological properties of acetylated corn and potato starches, prepared using acetic anhydride at different levels (4–12 g), were compared. Corn starch showed lower acetyl (%) and degree of substitution (DS) than potato starches under similar experimental conditions. The acetylated corn and potato starches showed slightly higher amylose contents than their counterpart native starches. Acetylated starches showed higher swelling power, solubility and light transmittance than native starches, which subsequently increased with the increase in acetic anhydride concentration in the reaction medium. The extent of change in these properties, as a function of acetic anhydride concentration, was significantly higher in potato than corn starches. Both potato and corn starches were fused after conversion to acetylated starches; however, this effect was more pronounced in the former under similar reaction conditions. The syneresis (%) of both acetylated and native starches increased during storage at 4 °C; however, the increase was less pronounced in acetylated starches.
Corn, rice, wheat and potato are the main sources of starches which differ significantly in compo... more Corn, rice, wheat and potato are the main sources of starches which differ significantly in composition, morphology, thermal, rheological and retrogradation properties. Cereal starches contain a significant quantity of phospholipids, while potato starch is rich in esterified phosphorus. Potato starch exhibits higher swelling power, solubility, paste clarity and viscosity than wheat, rice or corn starches. Morphological characteristics, such as shape and size of the starch granules, exhibit significant differences. Potato starch granules are smooth–surfaced, oval and irregular or cuboidal-shaped while corn, rice and wheat starch granules are angular, pentagonal and angular; and spherical and lenticular–shaped, respectively. Corn, rice and wheat starch granules are less smooth–surfaced than potato starch granules. Potato starch granules are largest (<110 μm) in size followed by wheat (<30 μm), corn (<25 μm) and rice (<20μm) starches. Gelatinization temperatures (To, Tp, Tc) and enthalpies of gelatinization (ΔHgel) of starches from different sources also differ significantly. Corn and rice starches generally show higher transition temperatures than wheat and potato starches while the ΔHgel values are higher for potato and wheat starches. Potato starch shows a higher tendency towards retrogradation than the cereal starches. The rheological properties, such as storage modulus (G′) and loss modulus (G″) of the starches from the different sources increase to a maximum and then drop during heating of all the starches. Potato starch shows highest peak G′, G″ and lower tan δ than corn, rice and wheat starches during the heating cycle.
Corn starch and starches separated from different potato cultivars were acetylated to evaluate th... more Corn starch and starches separated from different potato cultivars were acetylated to evaluate the effect of plant source on the physicochemical, morphological, thermal, rheological, textural and retrogradation properties of the starches. Corn starch showed a lower degree of acetylation than potato starches under similar experimental conditions. The degree of acetylation for different potato starches also differed significantly. Morphological examination revealed that the granules of acetylated Kufri Chandermukhi and Kufri Sindhuri starches tended to appear as fused and less smooth than native starch granules. Acetylation of corn and potato starches decreased the transition temperatures and enthalpy of gelatinization and increased swelling power and light transmittance. However, the change in these was greater in the potato starches with higher percentage of small sized granules. Acetylated starches showed higher peak G',G'' and lower tan δ than their counterpart native starches during heating. Among the starches from different cultivars, the change in the rheological parameters after acetylation differed to a significant extent. The retrogradation was observed to be negligible in the acetylated cooked starch pastes. Results implied that the change in functional properties of starches with acetylation depends on source and granule morphology of native starch.
Granulated cold water soluble (GCWS) starches were prepared from corn starch and starches separat... more Granulated cold water soluble (GCWS) starches were prepared from corn starch and starches separated from four potato cultivars using alcoholic-alkaline method. The morphological, thermal and rheological properties of GCWS corn and potato starches were studied. The amylose content of the GCWS starches from corn and potato starches were significantly lower as compared to their counterparts native starches. GCWS potato starches showed higher cold water solubility than GCWS corn starch. Cold water solubility of GCWS starches prepared from different potato cultivars also differed significantly. Native potato starch granules were larger in size (15–45 μm), smooth, oval and irregular or cuboidal shaped while native corn starch granules were smaller in size (5–18 μm), less smooth, rounded and angular shaped. Both corn and potato starches were distorted and indented during conversion to GCWS starches, however, this effect was more pronounced in potato starches than corn starch. The extent of distortion in GCWS starches differed significantly in starches prepared from different potato cultivars. The potato cultivars having starch with large sized granules showed more granular distortion as compared in those having small sized granules during GCWS starch production. Native corn starch showed higher transition temperatures and lower enthalpy of gelatinization (ΔHgel) than native potato starches. GCWS corn and potato starches did not show any gelatinization endotherm during heating between 20 and 100 °C. The rheological properties such as G′, G″, η′ and of GCWS corn and potato starches also showed significant variation, when subjected to frequency sweep testing. GCWS potato starches showed higher G′, G″, η′ and lower than GCWS corn starch. The G′, G″, η′ of the GCWS starches from both corn and potato increased and decreased with the increase in temperature. The turbidity of GCWS and native corn and potato starches increased during storage at 4 °C, however, the increase was less pronounced in GCWS starches.
Effects of fatty acids (myristic and stearic acid) on the rheological properties of corn and pota... more Effects of fatty acids (myristic and stearic acid) on the rheological properties of corn and potato starch during heating and cooling were investigated using a Carri-Med CSL2 dynamic rheometer. Potato starch showed a lower gelatinization temperature (TG′) as compared to corn starch. Potato starch had a TG′ of 61.2°C against 71.5°C for corn starch. The addition of both the fatty acids inhibited the swelling of the starch granules in both corn and potato starch and consequently, increased the TG′. The storage modulus (G′) increased to a maximum and then dropped during heating of both the starches. Potato starch showed a higher peak G′ value as compared to corn starch. Addition of stearic acid decreased the peak G′ in corn starch and increased the same in potato starch, while the addition of myristic acid resulted in a decrease in peak G′ in both the starches. The extent of breakdown in G′ during heating was higher for potato starch as compared to corn starch which confirmed the more rigid structure of corn starch granules. During cooling, the G′ values increased with decrease in temperature and with the addition of fatty acids. Corn starch showed higher peak loss tangent (tan δ) values than potato starch during heating. Tan δ values decreased during the cooling of corn and potato starch. Retrogradation (synersis) behaviour of both the starches heated in the presence of stearic and myristic acid during storage was also studied. The rate of synersis was more in potato starch than in corn starch. Synersis increased with the increase in storage duration and decreased with the addition of both the fatty acids.
The starches separated from five different Indian potato cultivars (Kufri Chandermukhi, Kufri Bad... more The starches separated from five different Indian potato cultivars (Kufri Chandermukhi, Kufri Badshah, Kufri Jyoti, Kufri Sindhuri and S1) were investigated for morphological, thermal, rheological, turbidity and water-binding properties. The starch separated from all the five potato cultivars had a granule size ranging between 15–20 μm and 20–45 μm. The shape of starch granules varied from oval to irregular or cuboidal. Starch isolated from cv. Kufri Badshah had largest irregular or cubiodal granules while starch from cv. Kufri Chandermukhi had small and oval granules. The transition temperatures and enthalpy of gelatinization (ΔHgel) were determined using differential scanning calorimetry (DSC). The enthalpy of retrogradation (ΔHret) of gelatinized starch was also determined after 14 days of storage at 4°C using DSC. Kufri Chandermukhi starch showed the lowest ΔHgel and ΔHret while Kufri Badshah starch showed the highest values. ΔHgel and ΔHret values of 12.55 J/g and 6.42J/g, respectively, for Kufri Chandermukhi starch against 13.85 J/g and 8.61 J/g, respectively, for Kufri Bhadshah starch were observed. Rheological properties of starches from different potato cultivars, measured using the Dynamic Rheometer during heating and cooling, also differed significantly. The starch from cv. Kufri Badshah showed the highest peak G′ and G″ and lowest tan δ. The starches having higher peak G′(G′ at gelatinization temperature) showed higher breakdown in G′ and vice versa. The turbidity of gelatinized aqueous starch suspensions from all potato cultivars increased with increase in storage period. Starches with low water binding capacity had higher G′ and G″ and lower tan δ values.
Effect of some common chemical modifications such as acetylation, hydroxypropylation and cross-li... more Effect of some common chemical modifications such as acetylation, hydroxypropylation and cross-linking on the physico-chemical, morphological, thermal and rheological properties of starches from different botanical sources have been reviewed. The distinguishing factors that affect the efficiency of modification are the starch source, amylose to amylopectin ratio, granule morphology, and type and concentration of the modifying reagent. The extent of alteration in the starch properties reflects the resistance or the susceptibility of a starch towards different chemical modifications. Modified starches with desirable properties and degree of substitution can be prepared by critically selecting a suitable modifying agent and a native starch source.
Starches separated from four potato cultivars were hydroxypropylated and their physico-chemical, ... more Starches separated from four potato cultivars were hydroxypropylated and their physico-chemical, morphological, thermal and rheological properties were compared. The extent of hydroxypropylation measured as molar substitution differed significantly among the starches from different potato cultivars. Kufri Jyoti hydroxypropylated starch showed highest molar substitution, while Kufri Chandermukhi hydroxypropylated starch showed the lowest. The hydroxypropylated starches showed higher swelling power, solubility, solubility in dimethyl sulphoxide (DMSO) and paste clarity than their counterpart native starches. Light transmittance of hydroxypropylated starches did not change significantly during refrigerated storage while a substantial decrease in the same was observed for native starches. SEM pictures showed that the hydroxypropylated starch granules from all the potato cultivars differed in shape and size from the native starch granules, and showed the presence of slight fragmentation and a distinct groove in their central core region along the longitudinal axis. Hydroxypropylation treatment showed more pronounced effect on large size granules than small size granules. The extent of granule disruption was observed to be higher for hydroxypropylated starch gels that later developed numerous rod shaped or fuzzy clustered microfibrils with diameters ranging from 15 to 20 μm, after 30 days of refrigerated storage. The studies on the phase transitions associated with gelatinization of starches showed lower gelatinization parameters (To, Tp, Tc, and ΔHgel) among the hydroxypropylated starches in which Kufri Jyoti and Kufri Sindhuri starches were the most affected. Hydroxypropylated potato starches exhibited higher peak G′, G″ and lower during rheological measurements on the dynamic rheometer. Whereas the native starches did not possess freeze-thaw stability, upon hydroxypropylation there was a pronounced decrease in the tendency towards syneresis.
The physicochemical, morphological, thermal and rheological properties of acetylated corn and pot... more The physicochemical, morphological, thermal and rheological properties of acetylated corn and potato starches, prepared using acetic anhydride at different levels (4–12 g), were compared. Corn starch showed lower acetyl (%) and degree of substitution (DS) than potato starches under similar experimental conditions. The acetylated corn and potato starches showed slightly higher amylose contents than their counterpart native starches. Acetylated starches showed higher swelling power, solubility and light transmittance than native starches, which subsequently increased with the increase in acetic anhydride concentration in the reaction medium. The extent of change in these properties, as a function of acetic anhydride concentration, was significantly higher in potato than corn starches. Both potato and corn starches were fused after conversion to acetylated starches; however, this effect was more pronounced in the former under similar reaction conditions. The syneresis (%) of both acetylated and native starches increased during storage at 4 °C; however, the increase was less pronounced in acetylated starches.
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Papers by Jaspreet Singh