Changes in Crystallinity and Gelatinization Phenomena of Potato Starch by Acid Treatment

The hydrolysis of potato starch by 1-N H₂SO₄/30% ethanol aqueous solution at 45°C increased linearly with increasing of hydrolysis time for 14 d. The relative crystallinity of native starch showed 0.343 and 0.350 by symmetrical reflection and transmission techniques, resp. The increasing ratio of relative crystallinity to hydrolysis time corresponded very closely with that of 1/hydrolysis residue up to 14 d. These facts suggest that only the amorphous region of the starch granules will be hydrolyzed by the acid. By differential scanning calorimetry the calorimetric enthalpy of potato starch containing about 200% moisture content was found to stay largely unchanged by acid treatment for 6 d. The swelling power at 70° and 80°C of potato starch reached to the minimum value and, moreover, from the gel-chromatogram patterns of the acid-treated starches, the crystalline region of the starch granules may begin to deteriorate slightly by acid treatment for more than 6 d, although the relative crystallinity by the X-ray diffraction method increased slightly with passing of hydrolysis time.     

On the Relationship between Specific Volume and Crystallinity of Starch

Specific volumes of starch, crystalline portion and amorphous portion are discussed and the crystallinity is calculated from the specific volume. The specific volume of starch is calculated from the density by extrapolation of the moisture content zero. The specific volumes of the amorphous portion seem to be almost the same as that of cellulose. One is 0.673 for potato, waxy corn and waxy rice and the other is 0.684 for sweet potato, tapioca, wheat and corn. The crystallinities of the starches calculated from the specific volumes with a special equation are reported.     

Studies on the Accessibility of Starch by Deuteration

Cellulose and the various starches were dried in vacuum line apparatus, deuterated in liquid deuterium oxide, and dried in the same apparatus. Their accessibility was determined by measurement of the maximum absorbance (a) and the integral absorbance (b) at the wave number of each OH and OD group band on the infrared spectra, and crystallinity was calculated from accessibility. Crystallinity of cellulose showed the reasonable values of 0.66 for (a) and 0.71 for (b). Crystallinity of starches was considerable lower than those by means of the X-ray diffraction. There are inaccessible regions (so called crystalline fractions) in the starch granules which are not able to be deuterated and, moreover, neither to contain nor to absorb moisture inside. The reason why crystallinity was so low might be attributed to dehydration in the amorphous region at high vacuum.     

On the Acid Resistance of Starch Granules

When potato starch was hydrolyzed to form Nägeli amylodextrin by 16% sulfuric acid at 30°C, only the amorphous portion of the starch granules was deteriorated. The crystallinity of Nägeli amylodextrin showing the hydrolysis ratio of 0.22 was 1.28 times as large as that of original starch. The hydrolysis process at above 45°C was given by two exponential equations. The value of acid resistance portion (C_o) at 30 and 38°C was 100%, while the values at 45, 50 and 55°C were 67, 38 and 18%, respectively. The high value of C_o generally showed the high acid resistance in the various starches. Sweet potato and waxy rice starches were more easily hydrolyzed than other starches, although they gave the relatively high value of C_o. Thus, it was slightly more difficult for low acid resistance portion of potato starch to be hydrolyzed than for that of other starches. Moreover, that of waxy rice was easily hydrolyzed.     

Study on Relative Crystallinity of Moist Potato Starch

The relative crystallinity of various moist potato starches were measured by X-ray diffractometer. The diffraction patterns showed to become sharp with increasing of the amount of sorption moisture. Both areas of crystallinity portion were proportionally correlated with the amount of moisture. On the assumption that crystallinity of cellulose is 70%, that of native potato starch was showed to be 24%.     

The Effects of Enzyme Hydrolysis on the Properties of Potato,Cassava and Amaranth Starches

X-ray diffraction method and differential scanning calorimetry were used to study the effects of enzyme hydrolysis on physico-chemical properties of potato, cassava and amaranth starches. Various hydrolysis procedures and different sources of enzymes were employed. The highest percentage of hydrolysis was obtained using the bacterial thermostable α-amylase following by the saccharification with amyloglucosidase. Enzyme treatment showed decrease in the degree of crystallinity of all hydrolyzed starch samples of A-type crystals. B-and C-types were weakened upon enzymatic hydrolysis at 60°C and completely dissappeared at 100°C. The gelatinization endotherm decreased for samples with low degree of crystallization and disappeared in samples with amorphous stage.     

Crystalline Parts of Three Different Conformations Detected in Native and Enzymatically Degraded Starches

We examined cereals and legume starches with different amylose contents, using X-ray wide-angle scattering. The parts of polymorphs in the crystalline regions and the crystallinity of the starches were determined. The high-amylose starches hold 74.6%-84.6% B-type and 15.4%-22.6% VH-type. Crystallinity of high-amylose starches is xc = 0.154–0.17. According to phase analysis of the scattering curve of wheat starch 6.8% B-type and 93.2% A-type are contained. Thus, in the crystalline phase wheat starch is more heterogeneous than maize starch. The residuary substance of heterogeneous hydrolysis of wheat starch at T1 =58°C is an insoluble sediment, which does contain already 17.1 % VH-Amylose. This is the proof of the amylose-lipid complex in the sediment. If the temperature of hydrolysis raised to 70°C, the VH,-amylose proportion increased to 80.5%. Since the crystalline VH- structures are detectable during heterogeneous hydrolysis as from T1 = 58°C, they seem to have contained already in native starch.     

X射线衍射在淀粉颗粒结晶度研究中的应用

本文介绍了X 射线衍射技术测定淀粉颗粒结晶度的几种不同方法以及各自的应用状况,分析比较了这几种方法的测定原理、优缺点,以及各自测定马铃薯淀粉、木薯淀粉、玉米淀粉、大米淀粉、小麦淀粉、糯米淀粉等常见淀粉的结晶度大小;最后,阐述了X 射线衍射测定淀粉颗粒结晶度的方法所存在的问题及可能的发展方向。     

三种晶型淀粉与月桂酸复合对其形貌结构和消化特性的影响

玉米淀粉、马铃薯淀粉和锥栗淀粉等糊化后的3种晶型淀粉通过高压均质与月桂酸作用形成淀粉-脂肪酸复合物,探讨它们的复合指数、形貌结构和消化特性的变化规律。结果表明,3种晶型淀粉均能与月桂酸复合,复合指数与复合物中直链淀粉含量呈显著正相关（P＜0.05）;电镜图可知3种晶型淀粉经糊化和高压均质处理后,淀粉表面变得凹凸不平,与月桂酸复合后体积增大,孔洞被填充,表面变得平滑;X-衍射显示3种晶型淀粉与脂肪酸的复合物在7.8°、13°和20°附近均出现新的衍射峰,说明已由A、B、C型均转为V型;玉米淀粉、马铃薯淀粉和锥栗淀粉与月桂酸复合后,其对应RDS含量分别降低了9.44%、9.01%和9.57%,SDS及RS含量显著增加（P＜0.05）,增强了抗消化性。     

Retrogradation of sweet potato amylose and amylopectin with narrow molecular weight distribution

Retrogradation of sweet potato amylose and amylopectin with narrow molecular weight distribution at different temperatures was investigated by X-ray diffraction (XRD). Atomic force microscope (AFM), scanning electron microscope (SEM) and light microscopy were combined to study the morphology of the molecular assemblies during retrogradation. Avrami equation was used to the retrogradation kinetics the of above starches by determining the crystallinity and the ratio of peak area of two distinctive peaks. It was found that only the ratio of peak area/total area at 2θ = ~16.3° could represent the crystallinity of retrograded starch-containing amorphous regions. Considering the crystallinity as retrogradation rate, only the retrogradation kinetics of sweet potato amylose could be analysed by Avrami equation, but not the amylopectin’s. All Avrami exponents n of amyloses at any temperatures were less than 1.0, indicating instantaneous nucleation and rod-like growth. AFM results showed that the maximum heights of layered structure for sweet potato amylose, amylopectin and blending of both were approximately 4800, 180 and 200 nm, respectively. The height of the former two decreased during storage, but the height of blending remained unchanged. Amylose served as nuclei of amylopectin during starch retrogradation.     

On the Relationship between Regain and Crystallinity of Starch

A formula for the relationship between regain and crystallinity of starch is given. Accessibility of crystalline portion of starch is in the range of that of cellulose. The saturated moisture state shows six molecules of water per glucose residue. The sorption cannot take place at the inside of crystalline portion of starch.     

Crystallinity of Sucrose by X-ray Diffraction as Influenced by Absorption versus Desorption, Waxy Maize Starch Content, and Water Activity

Crystallinity of sucrose in a mixture with waxy maize starch as affected by absorption and desorption in the range 0.33 to 0.97 a_w was studied by X-ray diffraction. Ratio of sucrose to starch peak areas was linear with weight ratios as expected. Sucrose crystallinity as determined by X-ray diffraction was found to be in excellent agreement with that calculated from sorption data. Sucrose in a mixture equilibrated by absorption to 0.33 and 0.75 a_w was about 80% crystalline. On absorption to 0.84 a_w, the mixture showed sucrose crystallinity reduced to 50%. However, on desorption to 0.33–0.84 a_w, the sucrose crystallinity was reduced to zero regardless of sucrose content.     

Effect of debranching and storage condition on crystallinity and functional properties of cassava and potato starches

Debranching starch by pullulanase is considered to improve the RS content of starch which is widely used to produce the starch‐based foods with high‐health benefit impacts. In this study, the cassava and potato starches were debranched by pullulanase, followed by an autoclave treatment and storage at −18°C, 4°C, or 25°C to investigate their crystallinity and functional properties. After debranching, the potato starch contained significantly higher CL (35.4 glucose units) than did the cassava starch (32.4 glucose units). The debranched cassava and potato starches after retrogradation at the storage temperatures had a typical B‐type crystalline structure although the native cassava and potato starches exhibited the different crystalline forms (A‐ and B‐type, respectively). The RS contents of the debranched cassava and potato starches significantly improved with higher RS content of the debranched potato starch than that of the debranched cassava starch at the same storage condition. The storage temperature significantly affected the RS formation of the debranched starches with the highest RS content at storage temperature of −18°C (35 and 48% for the debranched cassava and potato starches, respectively). The debranched starches had significantly lower viscosities and paste clarities but higher solubilities than did the native starches. As a result, the debranched cassava and potato starches can be considered for use not only in functional foods with enhanced health benefits but also in pharmaceutical and cosmetic industries.     

Hydration and physicochemical properties of small‐particle cassava starch

Acid hydrolysis followed by ball milling was applied to cassava starch in order to fracture the granules. Lintnerisation led to degradation first in the amorphous domains and increased the crystallinity. The resulting increase in internal defects and brittleness made the granules more susceptible to breakage upon milling. Ball milling, although leading to some degree of crystallinity loss, could effectively reduce the size of acid‐hydrolysed starch while the total double helix remained relatively unchanged. The resulting small‐particle starch was structurally more heterogeneous (wider T_m range). Swelling of small‐particle starch was accompanied by solubilisation of water‐soluble fragments at a temperature greater than 60 °C. The properties of individual granules are strongly influenced by the hydration and physicochemical properties of their amorphous and crystalline domains. © 2002 Society of Chemical Industry     

On Water in Potato Starch

Thermal analysis (TG and DTA) was carried out on potato starch dried in the air at room temperature as well as at 130°C, and also on that dried azeotropically with benzene. Water present in the matrix of potato starch influences the whole pathway of dextrinization up to at least 300°C. The mode of removal of water from air-dried starch also subtly changes the route of thermal decomposition of starch and magnitudes of thermal effects. The role of atmospheric oxygen in thermolysis is also documented.     

Effect of Hydrothermal Treatment on Formation and Structural Characteristics of Slowly Digestible Non‐pasted Granular Sweet Potato Starch

The formation and structural characteristics of slowly digestible non‐pasted granular starch in sweet potato starch were investigated under various hydrothermal treatment conditions. The moisture content of the sweet potato starch was adjusted to 20, 50 or 90%, and the starch was heated at 40, 55 or 100°C for 12 h in a dry oven. The relative crystallinity of the hydrothermally treated samples was decreased with increasing temperature, and the X‐ray diffraction patterns of the samples were altered from C_b‐type to A‐type. Microscopic observations did not reveal any changes in the starch granules of any samples except those with moisture contents of 50 and 90% that were heated at 100°C. When gelatinization parameters were examined, samples with moisture contents of 50 and 90% that were heated at 55°C and samples of all moisture contents that were heated at 100°C had peak temperatures higher than that of raw starch but gelatinization enthalpies lower than that of raw starch. The swelling factor of the samples heated at 40°C did not change significantly, whereas that of samples heated at 55 and 100°C was decreased at increased moisture levels. The sweet potato starch with 50% moisture content that was heated at 55°C had the highest content of granular slowly digestible starch, about 200% that of raw starch, although our study did not involve further hydrothermal treatment conditions. Further study is required to complete a process for more efficient production of heat stable and slowly digestible starch.     

Morphological,crystalline, thermal and physicochemical properties of cellulose nanocrystals obtained from sweet potato residue

Sweet potato residue (SPR), a by-product of sweet potato starch industry, was used as starting material to prepare cellulose nanocrystals. The method of sulfuric acid hydrolysis accompanied with ultrasonication and homogenization was used to prepare cellulose nanocrystals. The morphological, crystalline, thermal, and physicochemical properties of the cellulose nanocrystals were studied. SEM and TEM images showed spherical or elliptic granules of cellulose nanocrystals with sizes ranged from 20 to 40 nm. XRD analysis indicated that the cellulose nanocrystals retained the cellulose I crystalline structure, with a crystallinity of approximately 72.53%. TGA curves showed that the decomposition temperature of nanocrystals was decreased. These results showed that cellulose nanocrystals were successfully obtained from SPR and might be potentially applied in various fields, such as pharmaceutical and food additives, bio-nanocomposites, packaging, etc.     

Physicochemical Properties of Starch Isolated from Bracken (Pteridium aquilinim) Rhizome

Bracken (Pteridium aquilinum) is an important wild plant starch resource worldwide. In this work, starch was separated from bracken rhizome, and the physicochemical properties of this starch were systematically investigated and compared with 2 other common starches, that is, starches from waxy maize and potato. There were significant differences in shape, birefringence patterns, size distribution, and amylose content between bracken and the 2 other starches. X‐ray diffraction analysis revealed that bracken starch exhibited a typical C‐type crystalline structure. Bracken starch presented, respectively, lower and higher relative degree of crystallinity than waxy maize and potato starches. Ordered structures in particle surface differed among these 3 starches. The swelling power tendency of bracken starch in different temperature intervals was very similar to that of potato starch. The viscosity parameters during gelatinization were the lowest in waxy maize, followed by bracken and potato starches. The contents of 3 nutritional components, that is, rapidly digestible, slowly digestible, and resistant starches in native, gelatinized, and retrograded starch from bracken rhizome presented more similarities with potato starch than waxy maize starch. These finding indicated that physicochemical properties of bracken starch showed more similarities with potato starch than waxy maize starch.     

Physicochemical Characterization and Application of Yam (Dioscorea cayenensis‐rotundata) Starch as a Pharmaceutical Excipient

Yam starch from Dioscorea cayenensis‐rotundata complex was isolated and characterized by scanning electron microscopy (SEM), particle size analysis, X‐ray diffraction, differential scanning calorimetry (DSC), compaction and rheology, and compared to maize (Zea mays) and potato (Solanum tuberosum) starches. Yam starch exhibited a log‐normal distribution of flattened ovoid shaped granules with a mean particle size of 25 µm. X‐ray diffraction showed a C‐type crystalline pattern with the degree of relative crystallinity estimated to be 34%. DSC analysis suggests that the crystalline regions in yam starch are thermally and structurally more stable as in maize and potato. Irrespective of the relative humidity (39, 67, 78% R.H.) yam starch exhibited higher moisture uptakes than maize starch and lower than potato. Intermediate values of swelling power and amylose leaching were obtained for yam as compared to maize and potato. Compaction properties of yam and potato starches were similar. However, compacts from yam presented a relatively lower tensile strength. Aqueous starch systems (4%) of yam and maize starches showed analogous shear‐thinning (pseudo‐plastic) behavior suitably described by the power‐law model. These results support the potential use of yam starch as excipient comparable to potato starch in pharmaceutical solid forms and as thickening agent similar to maize in pharmaceutical applications.     

酸解马铃薯淀粉-油酸复合物的制备

以酸解马铃薯淀粉和油酸为原料制备酸解马铃薯淀粉-油酸复合物,运用X-射线衍射(X-RD)技术探讨了淀粉酸解时间、原料配比和淀粉浓度对复合物结晶的影响.结果表明:酸解马铃薯淀粉-油酸复合物为V-型结构,随着酸解时间的延长和原料配比的增大,衍射峰的强度越来越大,复合物的结晶结构越来越完整,但相互之间结晶度变化不明显,当原料浓度为2%时,所形成的复合物的结晶度最高,约为82.23%.