Characterization of new starches separated from different Chinese yam (Dioscorea opposita Thunb.) cultivars

The starches separated from four different Dioscorea opposita Thunb. cultivars were investigated for morphological, thermal, crystal, and physicochemical properties, such as amylose content, swelling power, solubility and water-binding capacity properties. Amylose content of D. oppositastarches from different cultivars ranged from 20.74% to 25.94%. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round to oval or elliptic. The mean particle diameter of starches ranged from 23.39 to 26.87 μm. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) were determined using differential scanning calorimetry (DSC). T_o, T_p and T_c varied from 73.6 to 74.8, 78.8 to 81.0, and 83.3 to 87.2 °C, respectively. D. opposita cv. Jinchengerhao starch showed the highest ΔH_gel values (12.48 J/g) while D. opposita cv. Baiyu starch showed the lowest values (8.413 J/g). The crystal type of starches separated from different D. opposita cultivars was a typical C_B-type pattern. The degrees of crystallinity of the four D. opposita cultivars starches were about 50.52%, 32.99%, 33.57% and 36.16%, respectively.     

Influence of molecular structural characteristics on pasting and thermal properties of acid-methanol-treated rice starches

Rice starches from TKW1, TNG67 and TCS17 varieties, differing widely in amylose contents (0.1, 18.3 and 29.2%) were treated at 45 °C for 1 h in methanol containing various amounts of HCl. The recovery, pasting properties, thermal behaviors, molecular size and chain length distribution of starch were observed. Starches exhibited widely different pasting and thermal behavior upon acid-methanol treated (AMT). Degradation of starches upon AMT affected the leaching extent and chain length of amylose. No obvious changes were found on chain length and content of chain fractions of amylopectin. The pasting viscosity of rice starch decreased with increasing concentration of HCl, and the pasting profiles depended on the variety of rice. The pasting profile of AMT-TNG67 starch showed a two-step increasing pattern during heating, while TKW1 and TCS17 starches showed smoothly increasing pasting curves. The relationship between pasting patterns of AMT-TNG67 starches with amylose leaching and two stages of swelling behavior of starch granules was investigated. Results indicated that the pasting of starch granules depend on the amount, as well as the chain length, of amylose in granules.     

Structural properties of chemically modified Chinese yam starches and their films

Modified yam starch and dual-modified yam starch were produced with propylene oxide, sodium trimetaphosphate and sodium tripolyphosphate. Gelatinization temperature and final viscosity of native yam starch were 79.2 ± 0.4°C and 5702 ± 3 cP. Results showed that the molar substitution and degree of substitution were increased with the volume fraction of propylene oxide from 6–12%, the highest of molar substitution and degree of substitution were 0.0445 ± 0.0003 and 0.0065 ± 0.0006, the final viscosity and setback of dual-modified yam starch were also similar. However, the gelatinization parameters showed an inverse trend. Starch modified with a mixture of sodium trimetaphosphate and sodium tripolyphosphate had higher phosphorus content and increased viscosity compared to starch modified with sodium trimetaphosphate. The peak viscosity of starch modified with propylene oxide was higher than that of native yam starch and the highest was HP12. The granular surface of modified yam starch and dual-modified yam starch appeared significantly embossed and indented, while. Modified yam starch film treated with 12% propylene oxide showed a more homogeneous fractured surface. The tensile strength and elongation at break (E) of starch films were affected by crosslinking reagents and propylene oxide, respectively. The best transparence and E were demonstrated in starch film that was modified with 12% propylene oxide. However, the best tensile strength was demonstrated in starch film that was modified with 8% propylene oxide, sodium trimetaphosphate, and sodium tripolyphosphate. The final viscosity of HP6C1 and HP6C2 was 27 ± 7 and 45 ± 9 cP, which was too low to form film.     

Film and pharmaceutical hard capsule formation properties of mungbean,waterchestnut, and sweet potato starches

Biodegradable films were developed using mungbean, waterchestnut and sweet potato starches as base raw materials. The physical and mechanical properties of the films were compared with gelatin and HPMC films. The same starches were used to develop hard capsules for utilization in the pharmaceutical industry as a substitute for gelatin or animal based products. Starches with high amylose content had excellent film and hard capsule forming abilities and properties compared to the starches with low amylase content. The starch films also had excellent oxygen barrier properties (0.048 ± 0.008 to 0.070 ± 0.009 fl m/m² s Pa), but water barrier properties (1.1 ± 0.5 to 1.8 ± 0.4 ng m/m² s Pa) were higher than LDPE (0.00064 ng m/m² s Pa) synthetic polymer films. The tensile strength values of starch films (12.1 ± 0.7 to 19.0 ± 2.2 MPa) were not significantly different from gelatin (19.5 ± 1.6 MPa) and HPMC (19.9 ± 1.2 MPa) films. In the case of elongation properties, starch films had lower values (42.2 ± 7.7 to 79.4 ± 9.2%) than gelatin film (122.0 ± 14.6%), but higher than HPMC film (13.8 ± 4.2%). Molecular (SEC-MALLS) and physical (viscosity) characterization of vegetable starches, indicated that the starches with high amylose content produced better biopolymer films and capsules compared to the starches with low amylose and high amylopectin content. Biodegradable films and hard capsules for pharmaceutical applications could be developed from vegetable starches with similar physical and mechanical properties as synthetic and gelatin products.     

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     

Physicochemical,thermal, and pasting properties of flours and starches of eight Brazilian maize landraces (Zea mays L.)

Both genetic and environmental factors create significant variation in the amount and quality of maize landrace constituents. Details on the flours and starch characteristics have not been fully investigated. The physicochemical, pasting and thermal properties of 8 promising cultivars were assessed in this study and those properties were correlated. Higher values of swelling and solubility (RJ – 13.14%; 14.39%), lipid content (MG – 5.53%), WBC (PR – 18.89%), and amylose content (PR – 27.43%) were found for those genotypes. Lower onset temperatures of gelatinization (To) were observed for RX-F1 (66.1 °C) as RX-F1 (68.7 °C) genotype showed the lower pasting temperatures. A wide range of viscosity values was found among the maize landraces (MG-F0, 343 mPa s and RJ-F1, 175 mPa s) as well as for the retrogradation (R8C-F1, 796 mPa s and RX-F1, 22 mPa s). ATR-FTIR spectroscopy revealed amylose, amylopectin, lipids, and proteins as major flours constituents and their differences were discriminated by PCA analysis.     

Formation of starch spherulites: Role of amylose content and thermal events

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 (T_gel), whereas waxy maize starch had lowest T_gel and enthalpy of gelatinisation (ΔH_gel). Similarly, a considerable variation in parameters related with crystalline melting (T_m1, T_m2 and ΔH_m1, ΔH_m2) 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).     

Molecular structure,rheological and thermal characteristics of ozone-oxidized starch

The effects of oxidation by ozone gas on the molecular structure, rheological and thermal properties of starch (corn, sago and tapioca) were investigated. Starch, in dry powder form, was exposed to ozone for 10 min at different ozone generation times (OGTs). Average molecular weight decreased in oxidized corn and sago starches but increased in oxidized tapioca starch. All oxidized starches exhibited non-Newtonian shear-thinning behaviour. Starch viscosity decreased drastically with increasing OGT. Young’s modulus for all oxidized corn and sago starch gels stored for 1 and 7 days at 4 °C increased significantly compared to unmodified starch. No differences were noted in gelatinization temperatures and gelatinization enthalpies of all oxidized starches compared to unmodified starch. Retrogradation enthalpy increased markedly in corn starch after 1 min OGT. These results show that the extent of starch oxidation varies among starches of different botanical origins under similar ozone treatment conditions.     

Physicochemical,morphological, structural,and thermal characteristics of starches separated from Bulbus fritillaria of different cultivars

The starches studied from the nine Fritillaria species had differently shaped and sized granules but all of them showed the presence of smooth, round, or elliptic‐shaped, indicating that the isolation process did not destroyed the starch granules. The nine Fritillaria starches presented different AM content, moisture content, ash content, particle size, swelling power, solubility, water absorption capacity and light transmittance. The starches isolated from Chuan‐Beimu species exhibited a higher amount of crude protein content and lower amount of AM than other the groups, which had lower swelling power, higher solubility and light transmittance. All the nine Fritillaria starches had an XRD pattern of the B‐type. In addition, F. hupehensis, F. walujewii and F. ussuriensis starches with fairly large‐sized or irregular granules had higher T_p and ΔH_gel values than that isolated from the four Chuan‐Beimu species. The results obtained yielded information about the possible behavior of these starches when being used in certain applications. Cluster analysis results showed that this classification method based on macromolecule chemical compounds (starch) is original and credible in the quality control of various Beimu. In addition, it provided more information to the authentication systematics taxonomy methods including morphological, histological and molecular biological techniques of Fritillaria species.     

Physicochemical, pasting and thermal properties of tuber starches as modified by guar gum and locust bean gum

This study was carried out in order to compare the functional characteristics of isolated starch from five tuber crops, yam, taro, sweet potato, yam bean and potato, as well as effect of guar gum (GG) and locust bean gum (LBG) on pasting and thermal properties of tuber starches. The results showed that total amylose content of five tested starches ranged from 17.85% to 30.36%. The results of pasting behaviour showed that potato starches exhibited the highest peak viscosity and yam starch presented a stable curve with little breakdown viscosity. Addition of GG and LBG resulted in a significant increase in peak, final viscosity, breakdown and setback viscosity for all tuber starches ( P  < 0.05), but a slight decrease in pasting temperature. The gelatinisation enthalpy (Δ H ) for starches with GG and LBG was slightly lower than those of the starches alone in yam and sweet potato, but not in taro and yam bean.     

Effects of mucilage on the thermal and pasting properties of yam, taro, and sweet potato starches

This study investigates the effects of water-soluble mucilages (0, 2.5, and 5 g/100 g; w/w, dry basis) on the thermal and pasting properties of isolated starches from three root and tuber crops. The results show that yam tuber presents the greatest level of mucilage and also possess the largest amylose content of the three isolated starches. The addition of mucilage caused a remarkable increase in the temperature of gelatinization for the three tested starches due to the competition for water during starch gelatinization. Furthermore, adding mucilage increased the phase transition temperature range (Tc-To) of starches but decreased enthalpy (ΔH). However, although the pasting temperature increased with the addition of mucilage into tuber starches, it did not change that of taro starch. The peak viscosity of taro and sweet potato starches decreased significantly as their mucilages were added into each starch suspension system (p < 0.05). However, the addition of mucilage slightly increased the viscosity of yam starch. Furthermore, the addition of mucilage slightly increased the swelling power of yam and taro starches, but did not change that of sweet potato starch.     

Effect of succinylation on the physicochemical,rheological, thermal and retrogradation properties of red and white sorghum starches

Starches isolated from red and white sorghum were modified with succinylation. After modification proximate composition, moisture content, ash, protein and fat were reduced in percentage. Increase in swelling power was observed and did not show any significant change in solubility. Swelling and solubility were pH dependent with higher values obtained at pH 12 in both native and modified starches. At pH 4 both succinylated red and white starches had lower solubility.     

Comparison of the morphological,crystalline, and thermal properties of different crystalline types of starches after acid hydrolysis

A‐type maize starch, B‐type Fritillaria ussurensis, and C‐type Rhizoma dioscorea starches were hydrolyzed (32 days) with 2.2 N HCl. Regardless of the crystallinity level, starch with predominant B‐crystalline type was less susceptible to acid degradation than A‐type and C‐type starches, and initial rates of hydrolysis in B‐type was lower than others. The SEM and XRD results revealed that different types of starch displayed different hydrolysis mechanisms. The acid corrosion started from the exterior surface of A‐type and B‐type starches followed by the core of granules. However, the hydrogen ions primarily attacked the interior of the C‐type R. dioscorea starch granules and then the exterior. FT‐IR results confirmed that the amorphous regions in the starch granules were hydrolysed first. After 8–32 days of hydrolysis, the acid‐modified C‐type starch showed typical A‐type characteristics upon analysis of the XRD pattern. The average particle size of hydrolytic starch decreased with increasing hydrolysis time. The thermal results revealed that the hydrolytic starch showed lower ΔH than the native starch, while displaying higher peak width (T_c − T_o) value.     

Structures and Functional Properties of Starch From Seeds of Three Soybean (Glycine max (L.) Merr.) Varieties*

Structures and functional properties of starch from high‐protein, lipoxygenase‐free and low‐linolenic acid soybean variety seeds collected 20 d prior to harvest were investigated. Soybean starches exhibit C_B‐type X‐ray diffraction patterns, and granule diameters were very small (0.7 to 4 µm). Soybeans, 20 d prior to harvest contained 10.9–11.7% starch (dry basis). Apparent amylose content was 19–22% and absolute amylose content was 11.8–16.2%. Amylopectin weight‐average molar mass ranged from 5.1 to 11.3×10⁸ g/mol. Amylopectin average branch chain‐length, determined by anion‐exchange chromatography with an amyloglucosidase post‐column and pulsed amperometric detector, was very short relative to other starches (20.4–20.9). Onset gelatinization temperature ranged from 52–54°C, and ΔH was 12–13 J/g. Paste viscosity was low relative to other starches, especially peak (81–93 RVU) and final (93–106 RVU) viscosity. The apparent amylose content of the low‐linolenic acid soybean starch was significantly higher than that of high‐protein soybean starch, and absolute amylose content of low‐linolenic acid soybean starch was significantly higher than that of lipoxygenase‐free soybean starch. Based on our results, investigations on whether soybeans with different fatty acid oil composition have different starch structures would be worthwhile. Field replicates for each soybean variety exhibited high variation in starch characteristics, with further differences in starch structures and functional properties likely to be determined once variation is minimized.     

The effect of glutathione on the cohesiveness of pounded cassava, cocoyam, gari and yam

In order to understand the part played by glutathione on the cohesiveness of the tropical staple items of food, pounded cassava, cocoyam, gari and yam, varying amounts of glutathione were added to the foods after which the resistance to shear stress (cohesiveness) of each food was determined. In each pounded food the added glutathione immediately increased the food's cohesiveness. There was also a linearly increasing relationship between the foods cohesiveness and their endogenous glutathione contents on one hand and between the foods cohesiveness and foods protein contents on the other hand. Glutathione, therefore, increases the cohesiveness of tropical pounded foods by interacting with their proteins which then assume new conformations that increase the cohesiveness of the foods.     

Impact of annealing on the molecular structure and physicochemical properties of normal,waxy and high amylose bread wheat starches

Starch from normal (CDC teal), high amylose (line 11132) and waxy (99 WAX 27) bread wheat cultivars was isolated and its morphology, composition, structure and properties were studied before and after annealing. Granule diameters, total phosphorus, total amylose, lipid complexed amylose chains, crystallinity, gelatinization temperature range, gelatinization enthalpy, swelling factor (at 90 °C), and amylose leaching (at 90 °C), in the above starches ranged from 2–38 μm, 0.007–0.058%, 26.9–32.3%, 13.4–18.7%, 28.6–42.8%, 12.7–14.3 °C, 11.3–13.3 J/g, 27.6–72.2 and 22.2–26.2%, respectively. Peak viscosity, thermal stability, set-back and susceptibility towards acid hydrolysis followed the order: 99WAX27 > CDC teal > 11132, 11132 > CDC teal > 99WAX27, CDC teal > 99 WAX 27 > 11132, and 99WAX27 > 11132 > CDC teal, respectively. Susceptibility towards α-amylase hydrolysis followed the order: 99 WAX 27 > 11132 > CDC teal (<24 h) and 11132 > CDC teal > 99WAX27 (>24 h). The extent of retrogradation measured by spectroscopy and differential scanning calorimetry followed the order: 11132 > CDC teal > 99WAX27 and 99WAX27 > CDC teal > 11132, respectively. In all starches, concentration of amylose, lipid complexed amylose chains, gelatinization temperature range, swelling factor, amylose leaching, peak viscosity, final viscosity, set-back, light transmission, susceptibility towards α-amylase and acid hydrolysis and the proportion of small (2–8 μm) B-type granules decreased on annealing. Thermal stability and crystallinity increased on annealing. In all starches, gelatinization, enthalpy, retrogradation rate and amylopectin chain length distribution remained unchanged on annealing. Pores and indentations were formed on the granule surfaces of CDC teal and 99WAX27 starches on annealing.     

Comparison of Protein and Starch Content of Substituted and Complete Triticales (X Triticosecale Wittmack): Contribution to Functional Properties

The starch and protein content of substituted and complete triticales were quantitated and evaluated for their contribution to the functional properties of flours by means of the amylograph, farinograph, and the breadmaking test. Although no clear differences were observed in the starch and protein contents of the two triticale genotypes, a detailed analysis of their components revealed compositional differences between them. The amylose content was lower in the substituted triticales Duron S and Alamos 83 than in the complete types Tarasca 87 and Brumby II (P ≤ 0.05). Among the protein fractions, only the albumin and the total polymeric protein, although with an opposite effect, significantly contributed to the rheological properties of triticale doughs evaluated with the farinograph and in the breadmaking test. The SDS-PAGE test showed that the substituted triticales contained an additional HMW-GS band that was not observed in the complete triticales. Amylograph peak temperatures and maximum viscosities, farinograph development times, and loaf volumes of triticale doughs were higher in substituted triticale flours than those of the complete ones. This study demonstrated that the triticale genotypes can be differentiated not only by quantitating their starch and protein composition, but also by testing their functional dough properties.