Characteristics of native and enzymatically hydrolyzed Zea mays L., Fritillaria ussuriensis Maxim. and Dioscorea opposita Thunb. starches

Comparative studies on glucoamylase hydrolysis of A-type Zea mays L., B-type F. ussuriensis Maxim., and C-type Dioscorea opposita Thunb. were carried out by scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectra and differential scanning calorimetry (DSC). Maize, Fritillaria, Dioscorea starches were hydrolyzed with glucoamylase for 2, 4, 8, 12 and 24 h, respectively. The SEM and XRD results revealed that A-type, B-type starch and C-type starch displayed different hydrolysis mechanisms. A-type starch was digested with enzyme penetrating into starch granules through natural pores on the surface and disrupted the interior of the starch granules. The glucoamylase worked by attacking the surface of B-type starch and forming cracks. When endo-corrosion occurred, the internal part of the granule was corroded through small cracks. However, the glucoamylase primarily attacked the interior of the C-type starch granules and then the exterior of starch granules. FT-IR confirmed that the amorphous regions in the starch granules are firstly hydrolyzed and could be hydrolyzed completely as long as the hydrolysis time is sufficient. The transition temperatures and enthalpy of gelatinization (ΔH_gel) were determined using DSC. According to the gelatinization parameters, it could be further proved amorphous and crystalline structures were hydrolyzed.     

Effect of water stress at different stages of grain development on the characteristics of starch and protein of different wheat varieties

The effect of water stress (WS) at 8 and 15 days post anthesis (DPA) on the characteristics of starch and protein separated from C-306, HD-2329, PBW-175, PBW-343 and NI-5439 wheat varieties was studied. WS-induced changes in A-, B- and C-type granules distribution were variety- and stage-dependent. A-type granules increased in response to WS at both stages in all varieties, the extent of increase being greater at 15 DPA. The proportion of B-type granules decreased in all the varieties, except C-306, in response to WS at 15 DPA. C-type granules also decreased in response to 15 DPA in all varieties, except HD-2329. The starch from wheat exposed to WS at 15 DPA showed lower amylose content, lipids content and pasting temperature, and higher peak viscosity, final viscosity and setback. DSC analysis of starches showed two endotherms (associated with the melting of crystallites and amylose–lipid [AML] complexes) during heating, and an exotherm (associated with reforming of AML) during cooling. Transition temperatures (T_o, T_p and T_c) of AML dissociation and association were lower for starch from wheat exposed to WS, the effect being more at 15 DPA. The changes in pasting and thermal properties of starch caused by WS were observed to be related to lipids, amylose content and distribution of granules. The effect of WS on accumulation of different dimethyl formamide-soluble and insoluble proteins was significant and variety dependent.     

湿热处理对不同晶型淀粉理化性质及消化性的影响

采用三种不同晶型淀粉即玉米淀粉(A型)、马铃薯淀粉(B型)、豌豆淀粉(C型)为原料,在水分含量为25%、温度120℃条件下湿热处理13 h,研究湿热处理对不同晶型淀粉的理化性质及消化性的影响。研究表明,与原淀粉相比,经湿热处理的三种淀粉的结晶结构均发生了改变,玉米淀粉由A型变为了A+V型,马铃薯淀粉和豌豆淀粉分别由B型和C型变为了A型;三种淀粉颗粒表面均出现了不同程度的破损;三种淀粉的部分颗粒的偏光十字的中心强度有所减弱;三种淀粉样品的糊化温度均升高,但A型和B型淀粉的焓值降低,而C型淀粉的焓值升高;三种淀粉的抗性组分含量均有所升高,抗消化性显著增强,其中C型淀粉变化最明显。     

Effects of Annealing on ultra-high pressure induced gelatinization of corn starch

Ultra-high pressure (UHP) can induce starch gelatinization at the room temperature, while the change of starch architecture could affect the gelatinization process. This work evaluated the effects of annealing on UHP induced starch gelatinization. Native and annealed corn starches were subjected to UHP treatment (300–600 MPa) for 15 min at room temperature. The scanning electron microscopy, confocal laser scanning microscopy, differential scanning calorimetry and X-ray diffraction analysis showed that UHP treatment partially disrupted the ordered structures of native and annealed starches, which made starch gelatinized gradually and a transformation in crystal type from type A to type B. However, compared with native starch, annealing (C3 and C24) delayed the internal and external structure destruction of starch granules, as well as induced a slower decrease in ΔH and relative crystallinity as increasing pressure. Therefore, the suitable UHP treatment can increase the pressure resistance of starch, or delay the UHP gelatinization process.     

Changes in functional characteristics of starch during water caltrop (Trapa Quadrispinosa Roxb.) growth

This study was carried out to establish the changes of physicochemical properties of Taiwan’s water caltrop (Trapa Quadrispinosa Roxb.) starch at various stages of maturity during growth. Investigations showed that the dry matter and starch contents of water caltrop increased from 9.7% to 25.61% and from 49.4% to 79.4% (d.b.), respectively, as growth progressed (from 14th to 42nd day after fruit development). The shape of the starch granules was smooth, oval and poly-angular during the growth period. The granule size of starch increased with increase of physiological age, ranging from 19.4 μm to 32.2 μm. The X-ray diffraction patterns could be classified as a typical A-type crystalline structure. Swelling power and solubility of water caltrop starch increased with increases of growth time. Starches obtained from water caltrop at the early stage exhibited a lower gelatinization temperature (T_o, T_p, T_c) and gelatinization enthalpy (ΔH) than did the late stage of maturity. The rapid viscosity analyzer (RVA) parameters suggested that water caltrop starch paste had a low breakdown, and appeared to be thermo-stable, at the early harvest time. The pasting temperature, peak viscosity, final viscosity and setback value of water caltrop starch increased as growth progressed. Different starch granular size and amylose content could be the major factors influencing starch physicochemical properties during maturity.     

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.     

Impact of mild acid hydrolysis on structure and digestion properties of waxy maize starch

In this study, the molecular structure of acid-treated waxy maize starch residues was investigated, and the in vitro digestibility of the residues with 2.2 N HCl at 35 °C for different time periods, was assessed. The granular appearance of waxy maize starch was destroyed and small fractions formed aggregates. A change in chain-length distribution profiles occurred with the degradation of shortest A chains and long B chains in amylopectin. The rise in the ratio of absorbance height at 1047 cm⁻¹ to the height at 1022 cm⁻¹, the intensities of major peaks, X_c, T_p, T_c, and ΔH were observed during mild acid hydrolysis, but the X-ray diffraction patterns displayed A-type for all starches. The amount of rapidly digestible starch increased, whereas the amounts of slowly digestible and resistant starch decreased. These results demonstrate that the amorphous regions of starch granules, including the shortest A chains and long B chains, are preferentially hydrolysed and affect the slow digestion and resistance properties of waxy maize starch.     

Characterization of proso millet starches from different geographical origins of China

The influence of geographical origin (Lvliang, Baotou, Gulang, and Jilin) on the physicochemical properties of proso millet (Panicum miliaceum L.) starches from China, and starch chemical compositions were studied. Scanning electron microscopy showed that starch granules from millet starches were polygonal and spherical with smooth surfaces with sizes ranging from 2.5 to 12 μm. X-ray diffraction showed that millet starches were typical of A-type starch granules with a mean crystallinity of 35.81%. The transition temperatures (T _o , T _p , and T _c ) and enthalpy of gelatinization (ΔH) of Lvliang, Baotou, Gulang, and Jilin proso millet starches were 66.81 to 70.01°C, 72.79 to 76.55°C, 78.30 to 82.44°C, and 10.4 to 14.46 J/g, respectively. Significant differences (p<0.05) were observed for the amylose content, granule size, peak temperature, gelatinization enthalpy, and peak viscosity temperature among the millet starches. Millet starches may have potential applications in production of puffed starch food products and other food items.     

Cross-linking of corn starch with phosphorus oxychloride under ultra high pressure

To investigate the effect of UHP treatment on the cross-linking reaction, normal corn starch was subjected to UHP-assisted reaction with a single addition level of POCl₃, at varied pressure levels ranging from 0.1 to 400 MPa. Swelling power, gelatinization, and pasting properties were assessed for all native and cross-linked starches. UHP-assisted reaction achieved a 12.5% level of conventional reaction time. UHP-assisted POCl₃ starch derivatives, reacted at 100–400 MPa, exhibited reduced swelling powers and gelatinization properties relative to that at 0.1 MPa, though both attributes did not possess any tendency depending on pressure levels. UHP-assisted POCl₃ reaction generated pasting viscosity profiles similar to those observed for conventional cross-linked starches. Pasting viscosity profiles were significantly different among various UHP treatments, though no trends were present. At 400 MPa, the UHP-assisted POCl₃ starch derivative revealed pasting viscosity profiles most similar to those of the conventional POCl₃ starch derivative.     

Granular structure and allomorph position in C-type Chinese yam starch granule revealed by SEM,C CP/MAS NMR and XRD

The crystalline microstructure and polymorphism of C-type starch from Chinese yam were evaluated by scanning electron microscope (SEM), ¹³C cross-polarization magic-angle spinning NMR (¹³C CP/MAS NMR) and powder X-ray diffraction (XRD) technique and acid hydrolysis method. Morphological changes during acid hydrolysis showed that the amorphous or the less crystalline areas were essentially located at the center part of C-type starch granules whereas the semi-crystalline and amorphous growth rings were found mainly in the outer part of the granules. ¹³C CP/MAS NMR and XRD results revealed that B-type allomorph was hydrolyzed more rapidly than A-type one. The amorphous or less crystalline areas were predominantly composed of B-allomorph whereas the outer semi-crystalline and amorphous growth rings were mostly composed of A-type allomorph. The A- and B-type allomorph coexisted in the individual C-type starch granule. B-type allomorph basically existed at the center part of the granules which was surrounded by the A-type allomorph in the peripheral part of granules.     

The effect of sodium chloride on the glass transition of potato and cassava starches at low moisture contents

The effect of NaCl on the glass transition of cassava and potato starches at low water levels (<20% dwb) was investigated. Sodium chloride (up to 6% of the starch dry weight) was mixed thoroughly with cassava and potato starches using a twin-screw extruder. The samples were equilibrated over saturated salt solutions (LiCl, CH₃COOK, MgCl₂, NaBr, CuCl₂ and NaCl) to give a range of moisture contents. The addition of sodium chloride caused a considerable reduction in the DSC measured glass transition temperature for both starches. For example, the T_g of cassava starch without and with 6% NaCl equilibrated at relative humidity of 11% was 166 and 136 °C, respectively. Similar reductions were found for potato starch. Although the starch sorption isotherms are affected by the addition of salt when T_g is plotted against water content as opposed to relative humidity a T_g reduction on salt addition is still observed. The possible reasons for the plasticization of starch by salt are discussed.     

A comparison of native and acid thinned normal and waxy corn starches: Physicochemical, thermal, morphological and pasting properties

The starches isolated from normal and waxy corn varieties were hydrolyzed with hydrochloric acid (0.14 mol equivalent/L) and evaluated for physicochemical and functional properties. Acid thinning decreased the amylose content and swelling power but increased the solubility. The light transmittance of acid thinned (AT) starch pastes was higher than those of their native starches after similar storage intervals. The scanning electron microscopic observation demonstrated that the acid thinning did not cause any disruption of the granular crystalline structure. Native normal corn starches showed lower onset temperature (T_o) and peak temperature (T_p) as compared to their counterpart AT starches, whereas the reverse was observed for waxy corn starch. Enthalpy of gelatinization (ΔH_gel) was lower in AT normal and waxy starches as compared to their native starches. The percentage of retrogradation (%R) was significantly higher for native corn starches as compared to their AT starches. A significant reduction in peak—(P_V), trough—(T_V), breakdown—(B_V), final—(F_V), and setback viscosity (S_V) was observed by acid thinning, and the reduction was more pronounced in AT waxy starches. Among AT starches, AT waxy starch showed the lowest values of P_V, T_V, B_V, F_V and S_V.     

Physicochemical,morphological, thermal and rheological properties of starches separated from kernels of some Indian mango cultivars (Mangifera indica L.)

The starches separated from kernels of five different Indian mango cultivars (Chausa, Totapuri, Kuppi, Langra and Dashehari) were investigated for physicochemical, morphological, thermal and rheological properties. Mean granule length and width of the starches separated from mango cultivars ranged between 15.8–21.7 and 8.7–14.1 μm, respectively. The shape of starch granules varied from oval to elliptical. Amylose content of mango kernel starches from different cultivars ranged from 9.1 to 16.3%. Totapuri kernel starch, with the largest mean granular size, had the highest amylose content, while Chausa kernel starch, with the lowest mean granular size had the lowest amylose content. 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 73.4 to 76.3, 78.1 to 80.3 and 83.0 to 85.7 °C, respectively. Chausa kernel starch showed the highest T_o, T_p, T_c, ΔH_gel and peak height index among starches from different mango cultivars. The rheological properties of the starches from different mango cultivars measured using a dynamic rheometer, showed significant variations in the peak G′, G″ and peak tan δ values. Totapuri kernel starch showed the highest peak G′, G″, breakdown in G′ and lowest peak tan δ values. The large-size granules of Totapuri kernel starch appeared to be associated with higher values of peak G′ and G″. The turbidity of the gelatinized aqueous starch suspensions, from all mango cultivars, increased with increase in storage period. Dashehari starch paste showed lower turbidity values than other mango cultivars.     

Effect of phytochemical extracts on the pasting,thermal, and gelling properties of wheat starch

Pasting, thermal and gel textural properties of wheat starch were studied in the presence of phytochemical extracts from pomegranate peel (C18), green tea (C53), Chinese hawthorn (C54), and Chinese gall (C46). All the four extracts increased the breakdown values and reduced the final viscosity. C18, C46, and C53 increased the peak viscosity. C18 and C46 reduced peak time and hot paste viscosity. All the four extracts reduced gel hardness. C46 increased gel adhesiveness. C46 facilitated the gelatinization of starch with earlier onset of T_o, T_p and T_c and a higher melting enthalpy whereas C18 and C54 prolonged the T_o, T_p and T_c and decreased the melting enthalpy. All phytochemical extracts caused earlier onset of T_o and T_p of amylose inclusion complex melting without altering the enthalpy. Scanning electron microscopy revealed that phytochemical extracts could cause looser gel matrices of dried wheat starch gels. Colour observation showed phytochemical extracts imparted different colours to wheat starch gels.     

微晶淀粉的制备及影响微晶晶型的因素研究

玉米淀粉经过酸、酶等催化水解后,再经过溶解、过滤、结晶、洗涤及干燥等步骤,可得到微晶淀粉。X-射线衍射分析表明,随着结晶温度的升高、结晶浓度的增大,微晶的晶型从B型向A型转化;短链淀粉有利于形成A型结构,而长链淀粉倾向于形成B型结构。     

Morphology and structural properties of high-amylose rice starch residues hydrolysed by amyloglucosidase

High-amylose starches are attracting considerable attention because of their potential health benefits and industrial uses. Enzyme hydrolysis of starch is involved in many biological and industrial processes. In this paper, starches were isolated from high-amylose transgenic rice (TRS) and its wild type rice, Te-qing (TQ). The morphological and structural changes of starch residues following Aspergillus niger amyloglucosidase (AAG) hydrolysis were investigated. AAG hydrolysed TQ starch from the granule surface, and TRS starch from the granule interior. During AAG hydrolysis, the content of amorphous structure increased, the contents of ordered structure and single helix decreased, and gelatinisation enthalpy decreased in TQ and TRS starch residues. The A-type polymorph of TRS C-type starch was hydrolysed faster than the B-type polymorph. The short-range ordered structure and B-type polymorph in the peripheral region of the subgranule and the surrounding band of TRS starch increased the resistance of TRS starch to AAG hydrolysis.     

Morphology and structure of chestnut starch isolated by alkali and enzymatic methods

The structure and morphology of starch from fruits of two chestnut (Castanea sativa Mill.) varieties, Martainha and Longal, isolated by alkaline (A3S) and enzymatic (ENZ) methods were assessed. Chestnut starch granules were found to be round and oval in shape, consisting of medium/small granules, with a mean granule size ranging between 9 and 13 μm. Isolated chestnut starch appeared to the naked eye as a white powder, with high values of L^∗, and the Longal variety produce starches duller than Martainha. No differences between samples were observed by FTIR analysis. The X-ray patterns of isolated starches are of C-type (more specifically of C_b type) with a relative crystallinity between 31.5% and 39.8%. The ¹³C CP/MAS NMR spectra are similar for both varieties but different for the used isolation methods. The amorphous phase in the starch granules isolated by A3S methods was lower than that of the starch extracted by the ENZ method, making the B-type allomorph in the C-type starch granules more evident than in the A-type. Those differences in the structure of isolated starches are shown by a lower degree of damage, and a higher level of crystallinity of starches isolated by the A3S method, which means that its original structure is less affected or partially destroyed. This study would be helpful to better understand the relationships among structure and functional properties for a eventual industrial application of chestnut starches.     

Glycerol-enhancing heat-moisture treatment of A-type rice and cassava starches and B-type potato and canna starches

Effects of glycerol on the heat-moisture treatment (HMT) of A-type rice and cassava starches and B-type potato and canna starches were investigated. Starch samples were soaked in water or glycerol solution, adjusted to 25% moisture, and then subjected to HMT at 100 °C for 1, 6, and 16 h. Pasting profiles of all four starches plasticised with water clearly showed the B-type potato and canna starches were more susceptible to HMT than the A-type rice and cassava starches. The effect of HMT on the pasting properties of glycerol-plasticised samples was inconclusive; the B-type canna and A-type cassava starches were altered, but not the B-type potato and A-type rice starches, which remained comparable to the water-plasticised samples. Thus, the type of plasticiser as well as the environment surrounding the crystalline region, which is specific to each starch type, also affect the alteration of starch during HMT.     

超高压辅助制备醋酸酯淀粉结构性质研究

以玉米淀粉为原料,乙酸酐为反应试剂,NaCl为反应介质,采用超高压辅助制备醋酸酯淀粉,利用光学显微、X-射线衍射、快速黏度分析技术对醋酸酯淀粉结构性质进行分析。研究表明,颗粒态醋酸酯淀粉结晶类型与原淀粉相同,当处理压力为600 MPa时淀粉糊化,颗粒结构被破坏,A型结晶向V型结晶转换,但糊化并不利于醋酸酯淀粉取代度的增加。适量NaCl的添加有利于超高压处理时淀粉颗粒态的维持,因而有效提高了醋酸酯淀粉的取代度。当NaCl溶液浓度为1.0%、乙酸酐添加量为2.0%、压力为400MPa时,所制备的醋酸酯淀粉取代度达到最大值(0.090),且表现出较高的峰值黏度(400.00cP)。     

Formation and stability of amylose ligand complexes formed by high pressure treatment

Starch can be gelatinized during high pressure processing in the presence of water, but to a greater or lesser extent. Starch gelatinization is often accompanied by the formation of amylose complexes, in particular when a thermal treatment is used. Four different starches were considered in this study: potato, broad bean (Vicia faba), pea and tapioca. A comparison between high pressure-induced starch gelatinization (HPG) and conventional thermal gelatinization (TG) was made. In the case of broad bean starch, selected complexing molecules were considered for both thermal and high pressure treatments. Cross polarization/magic angle spinning (CP/MAS) ¹³C NMR, X-ray diffraction and thermal analysis were used to monitor physico-chemical changes in the structure and microstructure of starch preparations. Decanoic acid and carvacrol were selected as complexing agents to track the formation of amylose ligand complexes. It was observed that B-type starch (potato) was more resistant to pressure than the A-type starches (tapioca, broad bean and pea) considered in this study. The results showed that amylose ligand complexes were formed during high pressure treatment (20 min at 500 MPa at temperatures of 20 °C and 40 °C). Decanoic acid induced the complexing of amylose in the V_6I type whatever the treatment used. On the other hand, the complexation of carvacrol appeared to depend on the temperature used during the high pressure treatment. It is assumed that carvacrol forms amorphous complexes with amylose during high pressure treatment. The amylose complexes were characterized by ¹³C CP/MAS NMR confirming the results obtained by X-ray analysis.Industrial relevanceDevelopment of innovative assembly of amylose + molecules of interest (i.e. antioxidant) using a mild processing (40 °C) instead of 90 °C. At 90 °C, some molecules are damaged or oxidized.The use of high pressure permits the production of larger amount of compounds than using conventional thermal treatment. The main reason is that there is no need to solubilise the molecule of interest.