添加淀粉和蛋白质对挂面力学特性的影响

通过向小麦粉中分别添加玉米淀粉、红薯淀粉、马铃薯淀粉以及大豆分离蛋白,制作挂面并对挂面的弹性模量、抗弯能力进行分析.结果表明:无论添加何种淀粉,挂面的弹性模量都会随添加量的增大而减小;添加大豆分离蛋白能使挂面弹性模量明显上升,若添加量超过0.6％弹性模量会有所回落但仍明显高于对照组.添加3种淀粉和大豆分离蛋白都会使挂面的抗弯能力下降.用断裂应力评价挂面抗弯能力比使用端部轴向位移量可靠度更高.综合考虑挂面的弹性模量及抗弯能力,挂面中玉米淀粉、马铃薯淀粉、红薯淀粉以及大豆分离蛋白的添加量分别不宜超过10％、5％、5％和0.8％.     

Chemical composition of Egyptian sweet potatoes

Two Egyptian sweet potato varieties were studied. The study showed considerable differences in chemical composition between the two varieties. The mineral found in the highest concentration was calcium, followed by magnesium, iron, copper, zinc and manganese.The chemical composition of sweet potato protein isolates indicated that the pulp had high protein content. The maximum solubility of nitrogen was at pH 12 and 17 amino acids were separated from the protein isolate of both peel and pulp of the Giza 69 variety and from the pulp of the Abees variety. The protein isolate of the Abees variety had only 16 amino acids.     

薯类淀粉种类对黄冈鱼面品质的影响

为研究薯类淀粉种类对黄冈鱼面品质的影响,测定了红薯淀粉（SPS1、SPS2、SPS3）、马铃薯淀粉（PS）、木薯淀粉（CS）的理化性质、糊化特性、粒径、溶解度及膨胀度,分析了这些性质与鱼面品质之间的关系。结果表明:不同薯类淀粉的理化性质、糊化特性、粒径、溶解度及膨胀度均存在显著差异（P<0.05）,红薯淀粉的糊化温度（78.37~79.97 ℃）最高,马铃薯淀粉的粒径、溶解度及膨胀度最大。不同薯类淀粉加工鱼面的质构特性、煮制品质、感官评价及色泽均存在显著差异（P<0.05）。红薯淀粉加工鱼面的硬度显著大于马铃薯淀粉、木薯淀粉（P<0.05）,红薯淀粉中SPS3加工鱼面的硬度最大。马铃薯淀粉加工鱼面的拉伸强度、吸水率及煮制损失率最大。SPS2加工鱼面的感官评价最高,CS加工鱼面的最低。不同薯类淀粉加工鱼面干燥前的色泽在亮度、红绿值和白度上差异显著（P<0.05）,但对鱼面干燥后的色泽影响并不明显。根据综合评分的大小对鱼面的品质进行排序为:SPS2>SPS1>SPS3>PS>CS。淀粉的糊化特性、直链淀粉含量、粒径与鱼面的品质具有显著的相关性（P<0.05）。     

超声波辅助制备冷水可溶性甘薯淀粉

以甘薯淀粉为原料,采用超声波辅助乙醇碱法制备颗粒状冷水可溶性甘薯淀粉,系统研究了淀粉乳浓度、乙醇浓度、碱用量、超声波功率和超声波时间对冷水可溶淀粉溶解度的影响。在单因素试验基础上,通过Box-Behnken响应面优化制备条件,得到最佳的反应条件为:淀粉乳质量浓度4.0 g/100 m L,乙醇体积分数81%,超声波功率为300 W,超声时间22 min。经验证,在最佳条件下,所制得的甘薯淀粉溶解度达到96.38%,回归模型预测值与实测值的相对误差1%。研究结果表明,超声波在制备冷水可溶性甘薯淀粉方面有一定的应用前景。     

乙酰化对红薯淀粉性质的影响

以红薯淀粉为原料,醋酸酐为乙酰化剂,制备低取代的乙酰化红薯淀粉.通过制备不同取代度乙酰化淀粉(DS 0.044～0.096),与红薯原淀粉进行比较,对乙酰化淀粉的透明度、凝沉性、溶解度、溶胀度、黏度和质构特性等进行深入研究.结果表明,与原淀粉相比,红薯淀粉经乙酰化作用后,凝沉性明显减弱,乙酰化红薯淀粉透明度、溶解度和溶胀度都随着取代度的增加而增加,且明显高于原淀粉.乙酰化红薯淀粉的糊化温度降低6～10℃,最终黏度和回生值显著降低,硬度显著降低.     

Ultrasound-treated starch: SEM and TEM imaging,and functional behaviour

Potato, wheat, corn and rice starch granules were suspended in water or ethanol and sonicated at frequency of 20 KHz and power 170 W for 30 min. The effect of ultrasonic treatment on starch structure was assessed on the basis of blue value (BV), A₆₈₀/A₅₄₅ ratio and λ_max determinations. The results showed that modification of starches in both solvents led to the reduction of all parameters connected with the starch–iodine complex. However, depolymerization of starch was higher when it was sonicated in water than in ethanol (e.g. BVs for potato starch: native and sonicated in water and ethanol were equal, respectively, 0.306, 0.275, and 0.279). Starch granules were also observed under scanning and transmission electron microscopes. The main effects of ultrasonic action were cracks and depressions on the surface of granules, which were especially well seen in the case of potato and wheat starches. Ultrasonic treatment, especially in water, influenced functional properties of starch causing an increase of fat and water absorption, least gelling concentration (except potato starch), solubility and swelling power, and a decrease of starch paste viscosity. Effect of ultrasounds on clarity of pastes was rather small, except potato starch for which its value increased from 70.3 to 82.5% after sonication in water.     

Semi-continuous Hydrolysis of Sweet Potato Raw Starch by Chalara paradoxa Glucoamylase

Effect of preservatives was investigated on semi-continuous digestion of sweet potato raw starch by Chalara paradoxa glucoamylase which digests both raw and gelatinized starch. Potassium metabisulfite strongly inhibited raw starch digesting activity (RDA) although gelatinized starch digesting activity was only slightly inhibited. Potassium sorbate, among the preservatives examined, showed the weakest inhibition (below 10%) on RDA. In the presence of potassium sorbate, semi-continuous digestion of sweet potato raw starch in a 20L scale hollow fiber UF membrane pilot reactor proceeded efficiently at 30% (w/v) initial concentration of raw starch at pH 5.0 and 40°C. Glucose production was 5.7 to 6.0 g/hr/L.     

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.     

Legume and Cereal Starches — Why Differrences in Digestibility? Part 1: Isolation and Composition of Legume (Greengram and Bengalgram) Starches

A range of starch granule populations varying in size and shape characteristics was isolated from greengram (CG) and Bengalgram (BG) flours. All the starches were non-ionic and exhibited single state swelling with hihg solubility in water, but extensive solubility in DMSO. The starch content of the different populations varied from 40-80%, whereas the protein and lipid contents of the isolates I to III were lower than those of the isolate IV. Their amylose content ranged between 32-46%. Brabender viscograms indicated low values for peak and setback viscosities in the case of BG starch compared to GG starch. Fatty acid analysis of the lipid fractions indicated predominance of palmitic acid. GG starch exhibited a slightly higher in vitro digestibility than BG starch.     

Enzymatic hydrolysis of granular native and mildly heat-treated tapioca and sweet potato starches at sub-gelatinization temperature

The effect of mild heat treatment (below gelatinization temperature) towards the susceptibility of granular starch to enzymatic hydrolysis was investigated. Tapioca and sweet potato starches were subjected to enzymatic hydrolysis with a mixture of fungal α-amylase and glucoamylase at 35 °C for 24 h. Starches were hydrolyzed in native (granular) state and after heat treatment below gelatinization temperature (60 °C for 30 min). The dextrose equivalent (DE) value of heat-treated starch increased significantly compared to native starch, i.e., 36–50% and 27–34% for tapioca and sweet potato starch, respectively. Scanning electron microscopy examination showed that enzymatic erosion occurred mainly at the surface of starch granules. Hydrolyzed heat-treated starch exhibited rougher surface and porous granules compared to native starch. X-ray analysis suggested that enzymatic erosion preferentially occurred in amorphous areas of the granules. The amylose content, swelling power and solubility showed insignificant increase for both starches. Evidently, heating treatment below gelatinization temperature was effective in enhancing the degree of hydrolysis of granular starch.     

Fat Mimicking Properties of Citric Acid Treated Sweet Potato Starch

Fat mimicking properties of citric acid treated sweet potato starch were investigated in this present study. Citric acid treated sweet potato starch was prepared by treating the native sweet potato starch with 3% citric acid for 6 h at a temperature of 45°C. Dextrose equivalent value of citric acid treated sweet potato starch was 2.05%. A significant increase in amylose content was noticed in citric acid treated sweet potato starch possibly due to the lyses of amylopectin fractions. The melting temperature of citric acid treated sweet potato starch was 51.44°C, which was close to the melting point of fat. Citric acid treated sweet potato starch exhibited superior water holding capacity and in vitro digestibility. Gel strength and enthalpy (?H) of citric acid treated sweet potato starch were comparatively lower than native sweet potato starch; correspondingly, citric acid treated sweet potato starch confirmed a low pasting profile. Native sweet potato starch and citric acid treated sweet potato starch exhibited a shear-thinning behavior. Acid treatment did not alter the granule size of native sweet potato starch (≈8 µm). Hence, this study concluded that citric acid treated sweet potato starch would be used as a potential fat replacer in food preparations due to its fat mimicking properties.     

紫甘薯饮料制备工艺研究

以紫甘薯为原料探讨紫甘薯饮料制备的工艺条件。比较α- 淀粉酶液化和高温液化两种方式对淀粉液化的效果,并进一步添加糖化酶进行淀粉糖化,同时探讨各工序对花色苷的影响,以饮料的可溶性固形物增长率、吸光度及色差值为考察指标。结果表明：鲜薯用两倍水打浆,加入0.020g/100mL α- 淀粉酶于70℃条件下酶解40min,再添加0.04g/100mL 的糖化酶在pH5.0 条件下糖化40min,既可获得理想的淀粉水解效果,又可尽量减少花色苷的损失。较好的饮料配方为30% 甘薯原汁、8% 蔗糖、0.05% 柠檬酸,其余为软水。采用该工艺条件可制备色香味俱佳的紫甘薯饮料。     

Preliminary Studies of the Chemical Composition and Sensory Properties of Sweet Potato Starch-Wheat Flour Blend Noodles

Preliminary studies of chemical composition and sensory properties of instant noodles from blends of wheat flour and sweet potato starch were carried out. Sweet potato starch was used to replace wheat flour at 30, 40, 50, 60 and 70%. Proximate, vitamin A, mineral analysis and sensory evaluation were carried out by standard methods. Results showed that the formulated noodles had higher carbohydrate (63.34 – 70.53%), moisture (4.34 – 4.97%) and vitamin A (11.62 – 35.00 mg/100 g) but lower protein (3.36 – 7.89%), fat (16.91 – 25.09%), calcium (0.73 – 0.89%), phosphorus (0.24 – 0.32%), iron (0.10 – 0.27%) and ash content (1.17 – 3.17%) than the commercial noodles from wheat flour. The noodles containing 30% sweet potato starch showed no significant difference (p > 0.05) from commercial noodles (100% wheat flour) in terms of colour, crunchiness, taste and general acceptability, with improved nutrient composition. It is concluded that production and consumption of wheat flour/potato starch blend noodles should be encouraged to increase the calorie and vitamin A intake in the diet, especially for children who are the major consumers of noodles; apart from helping to promote and improve the utilization of sweet potato tubers.     

不同植物来源淀粉之间的理化性质的比较

本研究比较了绿豆淀粉、马铃薯淀粉、红薯淀粉、大米淀粉及玉米淀粉的理化性质,结果如下：绿豆淀粉具有最高的直链淀粉渗滤和胶凝值,并且这两个指标均与表观和总直链淀粉含量呈高度的相关关系。尽管绿豆淀粉具有最高的直链淀粉含量,但它并不显示出热糊稳定性。红薯淀粉在加热过程中具有高的膨润力和峰值黏度、高的崩溃值以及低的离水率,这表明红薯淀粉颗粒在加热时能够自由膨胀,糊的热稳定性差,淀粉的老化速率较低,而大米淀粉则与红薯淀粉相反。五种淀粉具有不同的胶稠度,马铃薯淀粉最高,而大米淀粉最低。离水率与直链淀粉含量不呈现明显的相关关系,因此其值的大小可能受其他因素的影响。     

Physicochemical properties of the starchy flour extracted from sweet potato tubers through lactic acid fermentation

The efficiency of starch extraction from sweet potato tubers was improved by lactic acid fermentation using a mixed culture inoculum. Study of the properties of the starchy flour showed that there was a significant reduction in the starch content and consequently the soluble and apparent amylose contents of fermented samples from all six varieties used. A fall in peak viscosity and viscosity breakdown was observed for fermented samples, while the pasting temperature was enhanced significantly. The fermented flour showed greater solubility and reduced swelling. Differential scanning calorimetry studies indicated a delay in gelatinisation and a fall in enthalpy of gelatinisation of the starch on fermentation. Unlike cassava, all the properties of the starch from sweet potato tubers, ie viscosity, swelling, solubility, gelatinisation temperature, amylose content and starch content, were affected by fermentation, and variation was also observed among cultivars. Copyright © 2005 Society of Chemical Industry     

Physico-Chemical Characteristics of Starches from Sal (Shorea robusta) and Dhupa (Vateria indica) Seeds

Pure, white starches were isolated in ∼30% yields from defatted sal and dhupa meals. Both starches consisted of granules of varying size and shape characteristics, and contained considerable amounts of protein and lipid constituents. C 18:1, C 16:0 and C 18:0 were the major fatty acids present in both free and bound lipid fractions; whereas the latter in addition contained C 18:2 (∼20%). Both starches exhibited two-stage swelling in water; for sal starch the solubility was markedly lower but its swelling power was considerably higher. In DMSO the sal starch was readily soluble but not dhupa starch (only ∼20% solubility). The hot paste viscosity as well as set back viscosity of dhupa starch was much higher in comparison to those by sal starch. Very highly purified sal starch virtually exhibited no hot paste viscosity, and behaved like amylopectin-rich material. The latter had only 1.5% amylose as against of ∼24% in original sal starch. X-Ray powder patterns revealed sal starch to be of A-type and dhupa starch to be of B-type. Both the starch granules were susceptible for in vitro attack by human salivary α-amylase.     

一步和二步改性法对交联酯化甘薯淀粉性质的影响

以三偏磷酸钠(STMP)为交联剂,醋酸酐为酯化剂,对甘薯淀粉进行复合变性,通过一步和二步改性法制备交联酯化改性甘薯淀粉。比较了一步和二步改性法对交联酯化甘薯淀粉性质的影响。一步法指甘薯淀粉交联后调整酯化的条件,省去水洗、中和与干燥操作工序连续进行酯化;二步法为将制备的交联淀粉粉碎干燥后作为酯化变性反应的原淀粉。以峰值粘度和稳定性为指标测定。结果表明:一步法改性的交联酯化甘薯淀粉具有更好的峰值粘度和稳定性;二步法改性的交联酯化甘薯淀粉具有更好的抗凝沉性,溶解度和膨胀度略高于一步法,抗冻融性更好,但与一步法差别不显著。     

Isolation and Physico-chemical Properties of Enset Starch

Enset starch (Ensete ventricosum, Musaceae) has been examined for its chemical composition, amylose content and physico-chemical properties. The proximate composition of the starch on dry weight basis was found to be 0.16% ash, 0.25% fat, 0.35% protein, and 99.24% starch. The amylose content was 29%. Scanning electron microscopy (SEM) of enset starch granules showed characteristic morphology that was somewhat angular and elliptical. The starch has normal granule size distribution with a mean particle size of 46μm. It exhibits typical X-ray diffraction pattern of B-type with a distinctive maximum peak at around 17° 2θ Its moisture sorption pattern was similar to that of potato starch but much higher than maize starch. DSC parameters obtained from starch-water mixtures (1:2), namely, the enthalpy of gelatinization (ΔH: 21.6mJmg⁻¹), the onset temperature (T₀: 61.8°C), the peak temperature (T_p: 65.2°C) and the endset temperature (T_e: 71.7°C) were higher than those obtained for potato starch. Brabender viscosity curves of 6% starch paste showed lower peak viscosity (884 BU) than potato starch (1668 BU) but greater than maize starch (302 BU). The breakdown was also lower than potato starch but higher than maize starch. Retrogradation of enset starch was substantially greater than potato starch but less than maize starch.     

Influence of oxidative browning inhibitors and isolation techniques on sweet potato protein recovery and composition

Effects of oxidative browning inhibitors on sweet potato protein (SPP) recovery and quality were studied. Oxidative browning inhibitors successfully decreased sweet potato oxidative browning, but reduced both SPP extractability and recovery. Ultrafiltration/diafiltration processed sweet potato (UDSP) protein (at pH 4, 6 and 7) showed significantly (p < 0.05) higher yield, purity, solubility, thermal stability and amino acid constituents than that of isoelectrically precipitated sweet potato (IPSP) protein (at pH 4). The yield of UDSP proteins was more than twice that of IPSP protein. Denaturation temperature (T_d), enthalpy change (ΔH) and solubility (at pH 3 and 8) of UDSP proteins were in the ranges 82.89–90.29 °C, 6.34–11.35 (J/g) and 71.4–94.2%, respectively, while that of IPSP protein were 85.27 °C, 2.35 (J/g) 31.2% and 55.5%, respectively. Ratio of SPP essential amino acid to the total amino acid ratio ranged from 0.49 to 0.51. SPP in vitro digestibility and digestibility-corrected amino acid score (PDCAAS) ranged 70–80.7% and 44.79–51.08%, respectively.     

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