Molecular and physicochemical characterisation of starches from yam,cocoyam, cassava,sweet potato and ginger produced in the Ivory Coast

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 (T_g) 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     

Starch Properties of the Sweet Potato,Diploid Ipomoea trifida (H. B. K.) Don. and Tetraploid Hybrids

Starch properties were studied of two sweet potato cultivars (Tamayutaka and Minamiyutaka, both 2n=6x=90), two diploid (2n=2x=30) clonal strains of Ipomoea trifida (H. B. K.) Don. and their three tetraploid (2n=4x=60) hybrids (A200, A201 and A202). Starch size, iodine-absorption spectra, amylose contents in GPC analysis, pasting properties and X-ray powder diffraction patterns of the starches were investigated. The two I. trifida strains had smaller starch granules than those of the cultivars. The wavelength of maximum absorption and the extinction coefficients at 550, 600 and 650 nm were quite similar to each other among the cultivars and diploid strains. Amylose contents of 27% and 29% in the diploid strains were higher than those of the two cultivars. Amylose ratios of the two amylose subfractions were also compared among the starches. Starches of the diploid strains showed higher pasting temperatures and lower viscosities than the sweet potato starches. A C_b pattern of X-ray diffraction was shown by the cultivars while the diploid strains showed a C_a pattern. Starches of the tetraploid hybrids exhibited the properties rather close to the respective sweet potato parents.     

Granular Structure and Physicochemical Properties of Starches from Amaranth Grain

The granular structure and physicochemical properties of starches isolated from grain amaranth cultivar K112 (Amaranthus cruentus L.) were studied in this study. Detailed physical and chemical analyses were performed by determining the granular morphology, crystallinity, particle size, thermal characteristics, blue value, enzyme susceptibility, and pasting properties. Results showed polygon-shaped A. cruentus L. K112 starch granules. The average diameter was 1.38 μm, in which half of the diameter was <2.91 μm. An A-type X-ray diffraction pattern was revealed with intense peaks of 15.2°, 17.5°, and 23.2°. The peak viscosity was 181 BU and the breakdown value was 2 BU. Amaranth starch obtained the highest pasting temperature (70.7°C) and enzymatic digestibility (absorbance value = 0.41 ± 0.013) compared with corn, cassava, and sweet potato starches.     

Effects of heat treatment on the quality and storage life of sweet potato

The effects of heat treatment (50 °C) on the sprouting inhibition and spoilage of sweet potato roots (curing temperature: 29 °C) stored in wrapper‐type cold store (WTCS) were determined during year‐long storage. The quality attributes of sweet potato were also evaluated. The results indicated that hot water treatment significantly inhibited sprouting and decay of sweet potato for the storage period. It also showed that there were no significant differences in starch properties in terms of pasting properties, enthalpy and temperatures onset (T_O), peak (T_P) and endset (T_E) of gelatinisation of sweet potato starches among all the treatments, especially between heat‐treated and without‐heat‐treated samples. Also, hot water treatment did not have any significant impact on the internal components' quality of the roots: less than 4% of the year‐long stored roots were discarded due to spoilage. Heat treatment supplied a lethal dose of heat to surface pathogens and cauterised the eyes without damaging the nutritional and processing qualities of sweet potato. The success of storage experiments in prolonging sweet potato stored in WTCS by heat treatment was obtained from the effective control of weight loss, sprouting and decay without influence on quality characteristics. This new technique opens a new avenue to prolonging the storage life of sweet potato with good quality and minimal loss. Copyright © 2006 Society of Chemical Industry     

Digestibility and physicochemical properties of granular sweet potato starch as affected by annealing

The effects of annealing on the digestibility, morphology, and physicochemical characteristics of four types of granular sweet potato starches [Yulmi (YM), Yeonwhangmi (YHM), sweet potato starch from Samyang Genex (SSPS), and commercial sweet potato starch (CSPS)] were investigated. Annealing was performed at 55°C and 90% moisture content for 72 h. Morphology, the branched chain distribution of amylopectin, and the X-ray diffraction pattern remained unchanged during the annealing process. The slowly digestible starch content in annealed YM, YHM, and SSPS starches increased, but did not change in annealed CSPS. The gelatinization temperatures increased, but the gelatinization temperature range decreased with annealing. The swelling factor and amylose leaching decreased, while the close packing concentration increased. Rapid Visco Analyser analysis revealed that annealed starches possessed thermal stability and higher pasting temperatures. It is suggested that the enhanced packing arrangement formed during annealing impacts the digestibility and physicochemical properties of sweet potato starches.     

Physicochemical,Thermal, Morphological and Pasting Properties of Starches from some Indian Black Gram (Phaseolus mungo L.) Cultivars

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 (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) 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. T_o, T_p and T_c showed positive correlation with turbidity, pasting temperature and were negatively correlated to peak and breakdown viscosity.     

Some properties of potatoes and their starches II. Morphological,thermal and rheological properties of starches

The physico-chemical, morphological, thermal and rheological properties of the starches separated from different potato cultivars (Kufri Jyoti, Kufri Badshah and Pukhraj) were studied. The starches separated from the mealier cultivars (Kufri Jyoti and Kufri Badshah) showed lower transition temperatures (T_o; T_p and T_c), peak height indices (PHI), and higher gelatinization temperature range (R) and enthalpies of gelatinization (ΔH_gel) than the starch from the least mealy cultivar (Pukhraj). Swelling power, solubility, amylose content and transmittance values were observed to be higher for Kufri Jyoti and Kufri Badshah potato starches, while turbidity values were lower for these starches. The rheological properties of starches, measured using a dynamic rheometer, showed significant variation in the peak G′, G″ and peak tan δ values. Kufri Badshah and Kufri Jyoti starches showed higher peak G′, G″ and lower peak tan δ values than Pukhraj starch during heating and cooling cycles. Kufri Jyoti and Kufri Badshah starches showed higher breakdown in G′ than starch from the Pukhraj potato cultivar. The large-sized granules of the starches from Kufri Badshah and Kufri Jyoti appeared to be associated with higher values of peak G′ and G″ and consistency coefficient. Starch from the least mealy cultivar (Pukhraj) showed higher retrogradation, which increased progressively during storage at 4 °C for 120 h.     

Physicochemical,morphological, and thermal properties of starches separated from bulbs of four Chinese lily cultivars

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 (ΔH_gel) were determined using DSC. T_p varied from 62.52 to 65.25°C. Pinglu lily starch showed the highest ΔH_gel and gelatinization range (T_c–T_o) index among starches from four different lily cultivars.     

Effects of temperature on the physicochemical properties of starches extracted from microtubers grown from different potato cultivars

Twelve potato cultivars were grown as microtubers in constant environment chambers at two temperatures in total darkness for 28 days. For starch extracted from microtubers grown at 12 or 22 °C, the amylose content ranged from 25.0 to 29.0% (average 27.3 ± 1.4%) or 29.5 to 32.7% (average 30.9 ± 1.4%), the amylose/amylopectin ratio from 1:2.5 to 1:3.0 (average 1:2.7) or 1:2.1 to 1:2.4 (average 1:2.2) and the phosphorus content from 0.41 to 0.93 g kg⁻¹ (average 0.72 g kg⁻¹) or 0.38 to 1.67 g kg⁻¹ (average 0.97 g kg⁻¹) respectively. Two major fractions (F1 and F2) were obtained for isoamylase‐debranched starch (amylopectin), with the chain length (CL) averaging 56 ± 3 or 55 ± 1 for F1 and 20 ± 1 or 21 ± 1 for F2 from 12 or 22 °C growth temperature respectively. Peak gelatinisation temperature (T_p) and enthalpy (ΔH) were influenced strongly by growth temperature, with T_p ranging from 60.8 to 64.5 °C (average 62.1 ± 1.0 °C) or 66.9 to 69.6 °C (average 68.2 ± 0.9 °C) and ΔH from 13.3 to 16.9 J g⁻¹ (average 14.8 ± 1.0 J g⁻¹) or 11.3 to 19.5 J g⁻¹ (average 16.3 ± 2.4 J g⁻¹) from 12 or 22 °C growth temperature respectively. The collective data generated at 12 °C were generally more comparable to data published elsewhere (but discussed in the text) for the same potato cultivars grown in field plots (Perthshire). However, there were cultivar specific responses to field or constant environment chambers which make direct comparisons between starches produced from the two systems subject to some variation. Copyright © 2004 Society of Chemical Industry     

Effect of Acetylation on Some Properties of Corn and Potato Starches

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.     

The effects of blackcurrant and strawberry powder on the physicochemical and in vitro glycaemic response of starches derived from sweet potato (Ipomoea batatas) and potato (Solanum tuberosum)

Phenolic compounds have been shown to deliver numerous health benefits. Research has also shown that starch and phenolic compounds interact. This study aimed to investigate the effects of blackcurrant and strawberry powder on the physicochemical and in vitro predicted glycaemic response of sweet potato and potato starches. Sweet potato, or potato, starches were mixed with 0%, 5%, 10% and 15% (w/w) of blackcurrant, or strawberry, powder, to form blackcurrant and strawberry-enriched starch pastes. The results showed that enrichment with 5%, 10% and 15% blackcurrant or strawberry powder for sweet potato and potato starch significantly altered the pasting viscosity and colour profiles (P < 0.05), increased the phenolic content and antioxidant activities of starch pastes (P < 0.05). Blackcurrant or strawberry powders mixed with sweet potato or potato starches reduced amount of reducing sugar released during in vitro digestion. Addition of 15% blackcurrant powder for the starch exerted stronger in vitro antioxidant and hypoglycaemic properties than that of 15% strawberry powder. Collectively, these findings suggested that addition of blackcurrant or strawberry powder into sweet potato and potato starches manipulated the hypoglycaemic property of pastes.     

Hydrolysis of Tropical Tuber Starches by Bacterial and Pancreatic α-Amylases

Action of porcine pancreatic and Bacillus subtilis α-amylases on native tuber starches of yam (Dioscorea alata), sweet potato (Ipomea batatas) and tannia (Xanthosoma sagittifolium) was studied in comparison with the well known potato and cassava starches. Large differences in enzymes susceptibilities were observed when studied on 24h. Yam starch was 3.5% hydrolysed with 2,8 μkat amylase/g starch, three times less than potato and tannia starches while sweet potato starch was 53% hydrolysed, two times less than cassava starch. Except yam, level of hydrolysis was higher with porcine pancreatic amylase than with the Bacillus subtilis amylase while initial hydrolysis rate was lesser. Microscopic observations and image analysis pointed out that the polyhedric shaped granules of tannia, sweet potato and cassava starches were much more damaged than the spherical ones. Pitting occured preferentially on the edges of the granules and the enzymes penetrated into the starch granule by pores and canals of corrosion. Conversely to other starches, hydrolysis of yam starches evidenced greater differences between action of Bacillus subtilis and pancreatic α-amylases. The enzymes acted by pitting some parts of the granules surface, the number of pores and their size being related to enzyme source.     

Effect of cross‐linking on some properties of potato (Solanum tuberosum L.) starches

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 (T_o), peak temperature (T_p), conclusion temperature (T_c) and enthalpy of gelatinisation (ΔH_gel) 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     

Thermal Behavior of Selected Starches in Presence of Other Food Ingredients Studied by Differential Scanning Calorimetery (DSC)–Review

ABSTRACT: This review article highlights the thermal behaviors of selected starches that were studied using differential scanning calorimetery (DSC) with data shown in various research publications. The starches of sago, potato, sweet potato, cassava, yam, and corn are included in this overview. Our examinations indicate that thermal properties are highly affected by the type of starch, its amylose/amylopectin content, and the presence of other food ingredients such as sugar, sodium chloride, water, milk, hydrocolloids, and meat. When the heating temperatures of the starches were increased, the DSC measurements also showed an increase in the temperatures of the gelatinization (onset [T_o], peak [T_p], and conclusion [T_c]). This may be attributed to the differences in the degree of crystallinity of the starch, which provides structural stability and makes the granule more resistant to gelatinization.     

Dynamic rheological properties of rice flour‐starch blends

The dynamic rheological properties of blends of rice flour (RF) with six different commercial starches (sweet potato starch, potato starch, tapioca starch, waxy corn starch, hydroxypropylated potato starch, and hydroxypropylated tapioca starch) were evaluated. The magnitudes of storage modulus (G′) of all blend samples were higher than those of loss modulus (G′′) over most of the frequency range (0.63–62.8 rad · s⁻¹). In general, the dynamic moduli results of all blend samples showed that changes in G′ values were relatively greater than changes in G″ values after adding the starches when compared to RF. tan δ (ratio of G′′/G′) values (0.21–0.22) of the RF‐potato starch and RF‐hydroxypropylated potato starch blends were much lower than those (0.25–0.33) of other blends and RF, indicating that there is a more pronounced synergistic effect on the elastic properties of RF‐starch blend systems in the presence of potato starches.     

Physicochemical,Pasting, Thermal and Morphological Characteristics of Indian Water Chestnut (Trapa natans) Starch

Starch extracted from Indian water chestnut was investigated for its physicochemical characteristics. The results were compared with those obtained from two commercial starches (corn and potato). The pasting properties were tested in the Rapid Visco Analyser and thermal properties with a differential scanning calorimeter. Water chestnut starch possessed higher breakdown viscosity (BV) and setback viscosity (SV) than corn and potato starches. However, the pasting temperature of water chestnut starch was not significantly different from that of corn starch. Lower ΔH_gel values were obtained for water chestnut starch than for the other two starches whereas the onset, peak and conclusion temperatures of gelatinization (T_o, T_p and T_c) for water chestnut starch were quite comparable with corn starch. Scanning electron micrographs showed similarity in starch granule shape between water chestnut and potato starch with corn starch showing surface wrinkles on starch granule surfaces.     

Studies on the morphological,thermal and rheological properties of starch separated from some Indian potato cultivars

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 (ΔH_gel) were determined using differential scanning calorimetry (DSC). The enthalpy of retrogradation (ΔH_ret) of gelatinized starch was also determined after 14 days of storage at 4°C using DSC. Kufri Chandermukhi starch showed the lowest ΔH_gel and ΔH_ret while Kufri Badshah starch showed the highest values. ΔH_gel and ΔH_ret 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.     

Relationships between various physicochemical,thermal and rheological properties of starches separated from different potato cultivars

Various physicochemical, thermal and rheological properties of starches separated from Indian potato cultivars were related to each other using the Pearson correlation. Amylose content, water‐binding capacity (WBC), swelling power, solubility, ash content, transmittance, syneresis and consistency coefficient (K) were determined. Amylose content was significantly correlated with swelling power (r = 0.904), transmittance (r = 0.656) and syneresis (r = 0.777) of the starches. Thermal properties such as transition temperatures (T_o, T_p and T_c), gelatinisation range (R), gelatinisation enthalpy (ΔH_gel) and peak height index (PHI) of the starches were measured using differential scanning calorimetry (DSC). T_o, T_p and T_c were positively correlated with swelling power and negatively correlated with solubility and WBC. PHI was positively correlated with WBC and negatively correlated with ash content and swelling power. R had a negative correlation with WBC (r = ?0.726) and PHI (r = ?0.737). A positive correlation between R and T_c was observed. WBC was negatively correlated with swelling power (r = ?0.749). Syneresis of potato starches was positively correlated with transmittance, ash content, swelling power and amylose content. K was positively correlated with amylose content (r = 0.587). The results showed a significant variation in various functional and thermal properties of starches separated from different potato cultivars. Copyright © 2004 Society of Chemical Industry     

Comparative Investigation on Acid Hydrolysis of Sweet Potato Starches with Different Amylopectin Chain‐Length

The solubilization of starch from the new sweet potato cultivar “Quick Sweet” (QS) in 2.2 M aqueous HCl occurred at a much higher rate than that from normal sweet potato (NS). QS starch has an abnormal amylopectin chain‐length distribution with an unusually high percentage of short side‐chains. Two‐stage hydrolysis occurred in both cases. The apparent first‐order kinetic constants (k) were calculated for both stages of the hydrolytic process in both types of sweet potato starch. A more drastic difference between the investigated starches (k for QS and NS starches was 27.0×10^‐2 d^‐1 and 7.0×10^‐2 d^‐1, respectively) was observed for the first stage of the hydrolysis affecting the amorphous regions of starches whereas the rate for the second stage (the degradation of the crystalline part) for the starch from QS was only slightly higher. The role of the structural defectiveness of QS in decreasing the granular resistance to acid hydrolysis and increasing the absorptive properties of the granules for water molecules is discussed.     

Physicochemical Property of Huaishan (Rhizoma Dioscorea) and Matai (Eleocharis dulcis) Starches

The physicochemical properties of starch, the main component in tuberous root of Huaishan (Rhizoma Dioscorea) and corm of Matai (Eleocharis dulcis) was investigated and compared with those of a Japanese yam, “Yamanoimo” starch, and potato starch. Mean particle sizes of Huaishan and Matai starches were 24 ± 5 μm and 12 ± 5 μm, respectively. X-Ray diffraction pattern suggests that Huaishan starch was B-type or C-type just close to B-type and Matai starch was A-type or C-type just close to A-type. Apparently, the intermediate component (IntCom) of Huaishan starch, which was obtained by fractionation of the starch into amylose and amylopectin, may still contain amylose and amylopectin. IntCom of Matai starch has an intermediate nature between amylose and amylopectin. It is concluded that the amylopectin molecules of Huaishan starch contain a larger amount of longer branch-ed chains and those of Matai starch contain a larger amount of shorter branched chains. Amylograms of Matai and Huaishan starches suggest that the gelatinized starches are difficult to retrograde. Digestibility of Huaishan starch by an α-amylase was the highest among the tested starches.