Physicochemical and structural properties of starches isolated from corn cultivars grown in Indian temperate climate

Starches isolated from five corn cultivars namely C4, C5, C6, C8, and C15 were investigated for their physicochemical and structural properties. The amylose content of corn starches varied from 24.74 to 30.32 g/100 g among the cultivars. The starch granules showed polyhedral granule shapes and differences in their mean granule size ranged from 2.3 to 19.5 μm. The starch samples showed A-type diffraction pattern with strong reflection at 15.25, 18.11, and 23.33°. Pasting profile, textural, and thermal properties of corn starch showed the cultivar differences. Raman spectroscopy showed the major band intensities at 1340, 1082, 940, 865, 523, 485, 440, and 412 cm^?1. Syneresis and turbidity of gelatinized pastes of starches varied among the cultivars and increased progressively with the increase in storage period. The present study can be used for identifying differences between corn genotypes for starch quality and could provide guidance to possible industries for their end use.     

Rheological properties of starches from grain amaranth and their relationship to starch structure

Amaranth starch (Amaranthus cruentus L. and Amaranthus hypochondriacus L.) in this investigation possessed a relatively small and uniform granule size of a type “A” pattern obtained by X‐ray diffraction, with the degree of crystallinity ranging from 24.5 to 27.9%. This was followed by work on steady and dynamic rheological properties on shear of seven native amaranth starches. Aqueous pastes (5% solids) exhibited shear‐thinning behavior, and the flow behavior was fitted with the Herschel–Bulkley equation (regression coefficients were over 0.99). Cultivar V69 showed much higher G′ (storage modulus) and G″ (loss modulus) than the other samples and produced a solid‐like gel, which could be attributed to the high amylose content of its network. Correlation analysis revealed that amylose content was positively correlated with G′ and negatively with the loss tangent (tan δ) of the material.     

Retrogradation properties of high amylose rice flour and rice starch by physical modification

A new physical modification applied to prevent the retrogradation of rice flour and rice starch was investigated. This study examined the retrogradation properties of treated rice flour or rice starch paste by three stirring or heating-stirring, or without. The results proved that the retrogradations of rice flour and rice starch were both not substantially affected by three stirring modifications. However, three heating-stirring treatments had a marked effect on retarding the retrogradation of rice flour, but did not affect that of isolated rice starch. In the differential scanning calorimetry (DSC) analysis, modified rice flour by three heating-stirring exhibited the lowest retrogradation enthalpy (3.04 J/g dry matter) as compared to the control RF (5.93 J/g dry matter) and by three stirring (5.08 J/g dry matter). Meantime, it had almost the least recrystallization of retrogradation by X-ray diffraction (XRD). It was also found through scanning electron microscopy (SEM) that the granule structure of this modified rice flour had a more honeycomb-like structure and the lowest crystallinity as compared to the others.     

Chemical compositions,fine structure and physicochemical properties of kudzu (Pueraria lobata) starches from different regions

Three commercial kudzu starches from Vietnam, Japan and Korea were used to determine chemical compositions, isoflavone compounds, fine structure and physicochemical properties. The kudzu starch from Vietnam had polygonal granules, whereas the kudzu starches from Japan and Korea contained both polygonal and spherical granules. Total protein, lipid, ash and phosphorus contents present in these kudzu starches were less than 1% (starch basis). The kudzu starch from Vietnam and Korea contained both daidzein and daidzin, whereas the kudzu starch from Japan had only daidzein. These starches had similar actual amylose contents (22.2–22.9%). However, λ_max, blue value and apparent amylose contents of the kudzu starch from Vietnam were lower than those from Japan and Korea. Amylose molecules of the kudzu starch from Vietnam had the largest average degree of polymerization (DP_n) and number of chains (NC), followed by the kudzu starches from Japan and Korea. Amylopectin molecules of the kudzu starch from Vietnam also had the largest DP_n and NC, followed by the kudzu starches from Korea and Japan. X-ray diffraction patterns of the kudzu starches from Vietnam, Japan and Korea were A-type, C-type and B-type, respectively. The kudzu starch from Vietnam was found to have the specific characteristics such as significantly high gelatinization temperature, transition enthalpy and degree of crystallinity as compared to the kudzu starch from Korea and Japan.     

不同产地桄榔淀粉结构特性与理化性质研究

目的 本文旨在研究产地（广西宁明县、广西龙州县及海南省兴隆县）因素对桄榔淀粉的结构特性和理化性质方面的影响。方法 分别提取广西宁明县桄榔和海南省兴隆县桄榔中的淀粉,并结合市场购买的桄榔淀粉（产地为广西龙州县）进行对比研究,分别对淀粉分子链结构、结晶结构溶胀力、溶解度和冻融稳定性等进行对比研究。结果 3个不同产地的桄榔淀粉的直链淀粉含量存在显著差异（P＜0.05）,其中海南兴隆桄榔淀粉的直链淀粉含量最高(50.49 %)。3个不同产地的桄榔淀粉的形态大多呈现椭球形, 且广西宁明桄榔淀粉平均粒径最大。X射线衍射和红外谱图表明3个不同产地的桄榔淀粉分子的有序程度由高到低依次为：广西龙州桄榔淀粉(22.65%)＞广西宁明桄榔淀粉(19.02%)＞海南兴隆桄榔淀粉(18.72%)。随着温度的增加,3个不同产地的桄榔淀粉的溶解度与膨胀力均增加,其中海南兴隆桄榔淀粉的溶解度最大,广西宁明桄榔淀粉的溶胀力最大。而广西龙州桄榔淀粉的冻融稳定性最好。结论 3个不同产地的桄榔淀粉的结构特性与理化性质存在差异,可为其在工业应用上提供理论基础。     

In vitro digestibility,pasting, and structural properties of starches from different cereals

Starches isolated from seven different cereals were evaluated for their composition, physicochemical, in vitro digestibility, structural, morphological, and pasting properties. The in vitro starch digestion rate and estimated glycemic index (GI) of cereal starches were evaluated along with the impact of cooking on starch digestion. The cooking of starch slurries increased the rapidly digestible starch content from a range of 34.7–54.4% to a range of 60.5–78.5%. On the basis of hydrolysis index, the GI ranged from 83.6 to 91.8 and after cooking it increased from 95.1 to 98.6 for different cereal starches. Both the swelling power and solubility showed an increasing trend with rising temperature. Paste clarity of starches negatively correlated with fat content. The amylose content of various starches ranged from 17.7 to 24.7% and was negatively correlated to crystalline index (r = -0.975, p ≤ 0.05). XRD pattern revealed A-type pattern of crystalline starch, where crystallinity index ranging between 28.2 to 44.9%. FTIR revealed slight differences among chemical bonding of starches from different cereals. From scanning electron micrograph observations, wheat and barley starch granules proved smoother as compared to other cereal granules. Barley contained the highest (27.5 µm) and rice had the lowest (10.2 µm) size starch granules. The pasting properties were significantly (p ≤ 0.05) different for different cereal starches. Peak, breakdown, and final viscosities were the highest for maize starch (1725, 384, and 2112 mPa.s, respectively), whereas rice and oats exhibited the highest trough and setback viscosities (1420 and 954 mPa.s, respectively).     

Studies on noodle quality of potato and rice starches and their blends in relation to their physicochemical, pasting and gel textural properties

The physicochemical, pasting, and gel textural properties of potato and rice starches and their blends were studied in relation to their noodle making performance. Amylose content, swelling power and solubility values of potato starch were significantly (P ≤ 0.05) higher than for rice starch. Pasting properties showed higher peak, final and setback viscosity for potato starch as compared to rice starch. Texture profile analysis revealed that potato starch gel had higher hardness, cohesiveness and chewiness as compared to rice starch gel. Potato starch noodles showed higher cooked weight and cooking loss and were scored higher by sensory panellists especially with respect to transparency and slipperiness. On the other hand, rice starch noodles were more firm with lower cooking loss. Addition of potato starch to rice starch significantly (P ≤ 0.05) affected the noodle characteristics. Among the starch blends studied, blending of potato and rice starch in the ratio of 1:1 resulted in good quality noodles in terms of their lower cooking time, higher cooked weight, transparency and slipperiness. The results revealed the possibility of blending of potato starch with rice starch in equal proportions to produce noodles of acceptable quality.     

Comparison of the crystalline properties and structural changes of starches from high-amylose transgenic rice and its wild type during heating

A transgenic rice line (TRS) enriched amylose and resistant starch has been developed by antisense RNA inhibition of starch branching enzymes. In this study, gelatinisation and crystalline properties, swelling power, water solubility, morphological and structural changes of starches from TRS and its wild-type Teqing (TQ) were carefully investigated during heating. Compared to TQ, TRS starch showed higher gelatinisation temperatures, lower gelatinisation enthalpy and swelling power. Morphological and structural changes showed that TQ starch drastically swelled after 70 °C, then gradually disrupted with increasing heating temperature. The surrounding band of TRS starch restrained granule swelling, though the subgranules disrupted to form the cavity. The results of spectroscopic analyses indicated that A-type crystalline of TQ changed to amorphous starch after 75 °C, while C-type crystalline of TRS gradually changed to B-type crystalline after 75 °C, then became amorphous starch at 95 °C. These results add to our understanding of the effect of heating on the high-amylose rice starch.     

Amylose content,molecular structure,physicochemical properties and in vitro digestibility of starches from different mung bean (Vigna radiata L.) cultivars

Physicochemical and in vitro digestibility characteristics of starches isolated from six cultivars of mung bean (Vigna radiata L.) were studied. Significant differences (p < 0.05) were observed between the cultivars with respect to amylose content (29.9–33.6%), relative crystallinity (29.0 to 31.7%), particle diameter (16.2–17.1 µm) and molecular weight of amylopectin (260–289 × 10⁶ g/mol). The scanning electron micrographs revealed the presence of large oval to small round shape granules with average particle diameter of 16.2–17.1 µm. The X‐ray diffraction pattern was of the C‐type. The enthalpies of gelatinization and retrogradation were 8.9–10.3 and 4.6–6.3 J/g, respectively. The amounts of slowly digesting and resistant starch of mung bean followed the order: PBM‐1 > SML‐32 > ML‐613 > SML‐134 > ML‐267 > ML‐5 and ML‐5 > ML‐267 > SML‐134 > ML‐613 > SML‐32 > PBM‐1, respectively. The six starches exhibited significant (p < 0.05) differences in their pasting parameters. Correlation analysis showed that amylose content, granule diameter and relative crystallinity values were important in determining thermal, pasting and in vitro digestibility of starches.     

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.     

Studies on the physicochemical,morphological, thermal and crystalline properties of starches separated from different Dioscorea opposita cultivars

The physicochemical, morphological, thermal and crystal properties of the starches separated from four different Dioscorea opposita Thunb. cultivars (Taigu, Ribenbai, Wenxi and Zhongbowen) were studied. Amylose contents of D. opposita Thunb. starches from different cultivars ranged from 21.17% to 25.00%. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round or oval to elliptic or caky. The surface of the starch granules appeared to be smooth without any fissures. The average particle diameter of starches from different D. opposita Thunb. cultivars ranged from 25.90 to 28.06 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, T_c and ΔH_gel of D. opposita Thunb. starches ranged from 73.1 to 73.9, 77.6 to 80.4, 82.1 to 85.9 °C and 6.548 to 12.13 J/g, respectively. The crystal type of starches separated from different D. opposita Thunb. cultivars was a typical C-type pattern. The relative degree of crystallinity of the four D. opposita Thunb. cultivars starches were about 38.79%, 39.88%, 41.67% and 49.03%, respectively.     

Functional and dynamic rheological properties of acetylated starches from two cultivars of cassava

The starches derived from two different cultivars of cassava were modified with acetic anhydride. The increase in swelling power and solubility of the cassava starch (CS) pastes treated with different acetic anhydride concentration could be attributed to easier hydration, resulting from reduction of interaction between starch chains due to the substitution. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinisation (ΔH) of acetylated CS, were determined. The values were lower than those of native starches. Rheological properties of CS pastes (5% w/w) as a function of the degree of substitution were evaluated in dynamic shear force measurements. Magnitude of storage modulus (G′), loss modulus (G′′) and complex viscosity (Eta*) of acetylated CS pastes were determined also. Dynamic moduli (G′, G′′ and Eta*) values of acetylated sweet cultivar pastes were generally higher than those of native starch whereas the acetylated samples of the bitter cultivar were lower than those of native starch. The magnitudes of G′ were greater than those of G′′ and Eta* at all frequencies (ω). The fact that all the tan δ (ratio G′′/G′) values (0.7–0.48 and 0.25–0.44) were less than one is an indication that the samples are more elastic than viscous. The acetylated starches could find promising industrial uses in food products like Lemon curd and Mayonnaise and other non‐food applications.     

白酒丢糟酸水解制备木糖及其结构变化

采用混合酸水解法提取白酒丢糟中的木糖,并研究木糖提取过程中丢糟的结构变化。以木糖收率为指标,考查酸解温度、固液比、混合酸浓度和酸解时间4个因素对木糖提取效果的影响,利用正交试验优化工艺参数。结果表明,从丢糟中提取木糖的最优条件为温度110℃、固液比1∶12(g∶mL)、混合酸浓度1.5%和时间145min,该条件下的木糖收率为61.24%。经酸水解法提取木糖后,丢糟的木质纤维结构变化明显,孔隙率和比表面积增加,形貌结构改变,半纤维素和纤维素无定形区被降解,导致结晶度增加。     

Physicochemical properties of potato and cassava starches and their mutants in relation to their structural properties

Physicochemical properties [swelling power (SP), pasting behaviour and retrogradation] of five wild type (wt), five amylose free (amf), four high-amylose (ha) potato starches (ps) and one wt and amf cassava starch (cs) were investigated. While swelling of wtps occurred in two phases, amfps showed a very fast swelling and no gel of swollen granules was observed at higher temperatures (>90 °C). Haps underwent only restricted swelling. SP of cassava starches were lower than those of potato starches. Wtps leached mainly amylose (AM) during heating at low temperatures. Molecules of higher molecular weight (MW) leached out at higher temperatures. Longer amylopectin (AP) chains [degree of polymerisation (DP) > 18] inhibited swelling while short chains (DP < 14) favoured swelling. Starch pasting behaviour of 5.0 and 8.0% starch suspensions was studied using Rapid Visco Analyser (RVA). For 5.0% suspensions, increased levels of high-MW AP and decreased levels of AM molecules led to higher peak viscosity. Longer AP chains (DP > 18) depressed peak viscosity, while short chains (DP < 14) increased peak viscosity for both concentrations. At 8.0%, peak viscosity increased with starch granule size. After 1 day of storage of gelatinised starch suspensions, wtps and especially amfps showed only limited AP retrogradation. In contrast, the high enthalpies of retrograded AP (ΔH_retro) and peak and conclusion temperatures of retrogradation (T_p,retro and T_c,retro) of haps suggested partial cocrystallisation between AM and AP. Chains with DP 18–25 seemed to be more liable to AP retrogradation. Wtcs and amfcs did not retrograde at room temperature.     

Effects of microwave frying and different flour types addition on the microstructure of batter coatings

In this study, the influences of microwave frying and various flour types on microstructure of batter coatings were investigated. Control batter formulation contained only wheat and corn flour. To determine the effects of different flour types, 30% of the corn and wheat flour mix was replaced with chickpea, rice or soy flours. Frying was performed in microwave oven at 365 W (70%) power level for 1.5 min after bringing the oil temperature to 180 ± 1 °C. Samples were also fried in a conventional fryer at 180 °C for 1.5 and 5.0 min for comparison. Microwave fried samples had higher specific bulk volume and porosity values and also smoother inner surface as compared to conventionally fried samples. Porosity values of different batter formulations were in the range of 0.425–0.484 in 1.5 min microwave fried chicken samples and 0.348–0.392 in 5.0 min conventionally fried ones. Microwave fried samples had comparable or lower hardness values than the conventionally fried ones depending on the flour type used in batter formulation. Microstructure of fried batter was different for different batter formulations. Microwave fried control and chickpea flour containing batter provided formation of larger gas cells on the outer surface. Soy flour containing batter resulted in smallest size gas cells for both frying methods.