Isolation and Characterization of Starch-Iodine Positive Material Formed During Saccharification of Corn Starch

The increasing sophistication of customers has put pressure on corn wet-millers to improve product quality. One quality requirement is that glucose and corn syrups be free of material stained blue or green by iodine, i.e. free starch. Observations from a number of corn wet milling plants indicate that liquified corn starch may test negative for free starch but yield a positive iodine test after saccharification. Such dextrose hydrolyzates are difficult to process into product and often fail to meet customer specifications. The problem has been traced to small (0.2 to 1.0 μm) particles which are present in the starch supply. The particles exhibit an iodine spectrum similar to that of gelatinized corn starch. Enzymatic degradation of the particles was compared to that of gelatinized and non-gelatinized starch, and lipid-amylose complexes; the behavior of the particles most closely resembled nongelatinized starch. Extended liquefaction reduces, but does not eliminate the problem. Cellulase, hemicellulase, amylase, and proteasewere tested as adjuncts to normal glucoamylase products; none of these were effective in assisting hydrolsis of the particles under saccharification conditions. The particles can be completely eliminated by microporous filtration of liquefact or dextrose hydrolyzate.     

Physicochemical Properties of Non‐thermally Cross‐linked Corn Starch with Phosphorus Oxychloride using Ultra High Pressure (UHP)

Corn starch (20%, w/w) was non‐thermally and conventionally cross‐linked with phosphorus oxychloride (POCl₃; 0.01, 0.05, or 0.1%, based on dry weight of starch) at 400 MPa for 5, 15 and 30 min and at 45°C for 2 h, respectively. Swelling power and solubility of both non‐thermally and conventionally cross‐linked corn starches were relatively lower than those of native corn starch. The pressure holding time did not affect the solubility and swelling power of non‐thermally cross‐linked corn starches. X‐ray diffraction patterns and relative crystallinity were not significantly altered by both conventional and non‐thermal cross‐linking. DSC thermal characteristics of both non‐thermally and conventionally cross‐linked corn starches were not significantly changed indicating that the double helical structure of amylopectin was not influenced by both conventional and non‐thermal cross‐linking reactions. Both non‐thermal and conventional cross‐linking greatly affected the Rapid Visco Analyser (RVA) pasting properties, such as increase in pasting temperature and decrease in peak viscosity compared to native starch. This result suggests that in case of cross‐linking using POCl₃, both non‐thermal and conventional methods result in similar physicochemical properties and non‐thermal cross‐linking with POCl₃ can reduce the reaction time from 2 h to 15 min. This work shows the potential and possibility of non‐thermal starch modification and provides the basic and scientific information on the physicochemical properties of non‐thermally cross‐linked corn starches with phosphorus oxychloride using UHP.     

Effect of annealing on the functionality of Bambara groundnut (Vigna subterranea) starch–palmitic acid complex

Bambara groundnut is an underutilised African leguminous crop. This study investigated the effect of annealing on the complexing ability and functionality of Bambara groundnut starch with palmitic acid. Corn starch was included as the reference. Annealing created cracks and pores on the surface of Bambara groundnut and corn starches, respectively. Bambara groundnut starch had significantly higher amylose content, higher peak and final viscosities than corn starch. The peak viscosities of native Bambara groundnut and corn starches significantly reduced with palmitic acid addition. Greater reduction in peak viscosities was observed when the annealed starches were complexed with palmitic acid, suggesting that more palmitic acid was complexed after annealing. This was confirmed by XRD peaks and melting enthalpies. Pasting of native Bambara groundnut and corn starches with palmitic acid resulted in the formation of type I V‐amylose complexes, while type II complexes were formed from annealed starches pasted with palmitic acid.     

亚糊化热处理对玉米淀粉-胡椒碱复合物功能特性的影响

为探究在亚糊化温度下胡椒碱负载于玉米淀粉对其结构和理化特性的影响,本研究选用玉米淀粉在60℃下制备亚糊化玉米淀粉-胡椒碱复合物,并通过扫描电镜、快速糊化粘度测定仪、差示扫描量热、傅里叶变换红外光谱和X射线衍射等进行了表征。结果表明,胡椒碱成功负载到亚糊化玉米淀粉上,负载率为39.45%;扫描电镜结果显示淀粉颗粒膨胀的裂隙内部成功负载胡椒碱,粒径从天然玉米淀粉的15.20μm增大到亚糊化玉米淀粉的25.80μm,再到亚糊化玉米淀粉-胡椒碱复合物的81.90μm;胡椒碱的加入降低了亚糊化玉米淀粉的峰值粘度和谷值粘度;复合物红外光谱未产生新的基团或化学键,但胡椒碱的加入增强了玉米淀粉与胡椒碱的分子内和分子间氢键作用;X-射线衍射表明相对结晶度从天然玉米淀粉的23.52%升高到亚糊化玉米淀粉-胡椒碱复合物的28.15%,但是亚糊化处理未改变玉米淀粉的晶型结构;与天然玉米淀粉相比,亚糊化玉米淀粉和亚糊化玉米淀粉-胡椒碱复合物的凝胶焓值显著（P<0.05）降低。亚糊化玉米淀粉负载胡椒碱,胡椒碱的加入对亚糊化玉米淀粉的结构影响较小,但对其理化性质产生了显著的影响,并为淀粉与胡椒碱之间的相互作用...     

Viscosity and Gelatinization Characteristics of Hydroxyethyl Starch

Viscosity and gelatinization characteristics of corn and potato starches as well as their hydroxyethyl derivatives were investigated. The inherent viscosity increased from 164 in native corn starch to 209 in etherified one of DS 0.18. The etherified corn starch gelatinized at lower temperature than native corn starch due to their increase of DS. Maximum viscosity decreased from 93°C to 69°C for the modified corn starch. The retrogradation of starch was minimized by etherification as retrogradation ability of corn starch from its solution decrease from 22% to 6%. This is of great importance when starch is used as blood plasma volume expander. Variable results were obtained with etherified potato starch which might be due to its high contents of phosphorus.     

Potential interactions between starch and fruit pomace may impact the expansion ratio of direct expanded extrudates

Due to their dense characteristics, direct-expanded products fortified with insoluble fiber are generally not well accepted. Understanding the interactions between starch and fiber could help to effectively choose and modify ingredients to produce products containing high amounts of fiber. Therefore, this study aims to explain the interplay between two starches (native and waxy corn) and two pomace types (blueberry and cranberry). Blends up to 100% of pomace were extruded using a co-rotating twin-screw extruder. Raw material and milled extrudates were analyzed for their pasting and hydration properties. Fourier-transform infrared (FTIR) and solid-state nuclear magnetic resonance (NMR) spectroscopy were conducted to observe molecular changes. The expansion ratio (ER) significantly decreased as pomace was added and ranged from 3.85 for pure waxy corn starch to approximately 1 for blends that contained 80% pomace. Distinctions between the blends were observed. Particularly, at 20% of pomace inclusion, native corn starch with cranberry pomace showed a significantly higher ER. Different behaviors were also detected during the physicochemical analyses. A nonlinear trend between pomace level and water solubility as well as absorption was observed for native corn starch blends, suggesting that molecular interactions between the biopolymers occur. FTIR and NMR results give no evidence for new covalent bonds; hence, the most likely interactions occurring are hydrogen bonds. In addition to the dilution effect of pomace addition, the enhancement or weakening of such interactions between starch molecules by pomace compounds may reduce the ER.     

变性淀粉在午餐肉中的应用效果研究

将木薯变性淀粉与玉米原淀粉在午餐肉中的应用效果进行了对比,结果表明,添加了变性淀粉的产品在弹性、组织状态、口感及贮存稳定性方面明显优于玉米原淀粉。     

氧化淀粉对Cr(VI)的吸收研究

用玉米淀粉合成了一种带羧基的氧化淀粉,研究该合成氧化淀粉和玉米淀粉对Cr(VI)的吸收。玉米淀粉和氧化淀粉对Cr(VI)的吸收均受反应pH、温度、时间和吸收剂用量的影响。通过实验发现玉米淀粉对Cr(VI)的吸收各因素影响主次是pH>温度>吸收剂用量>时间;氧化淀粉对Cr(VI)的吸收各因素影响主次是pH>时间>温度>吸收剂。两者影响因素主次稍有不同,这可能是由羧基所造成的。实验结果表明氧化淀粉的吸收效果优于玉米淀粉。     

糯玉米淀粉高吸水性树脂制备及结构表征

为掌握糯性淀粉高吸水性树脂的制备条件及吸附性能,以糯玉米淀粉为原料,采用水溶液聚合法制备了糯玉米淀粉高吸水性树脂,系统分析了淀粉用量、引发剂用量、交联剂用量、单体中和度、反应温度等因素对树脂吸水倍率的影响,并对其结构进行表征。结果表明,糯玉米淀粉高吸水性树脂的适宜制备条件为:反应温度75℃,以单体质量计,单体与淀粉用量质量比为15∶1,单体丙烯酸中和度为pH4.8,引发剂过硫酸铵用量为0.15%,交联剂丙三醇用量为0.11‰,此时所得树脂的吸水倍率为1 641.78 g.g-1。红外光谱扫描结果表明,糯玉米淀粉与丙烯酸发生了接枝共聚反应。     

Prüfung der Umweltverträglichkeit neu entwickelter Polymerwerkstoffe auf der Basis nachwachsender Rohstoffe durch ein einfaches Testsystem

The OxiTop^®-System was used to highlight the differences in biodegradability and environmental acceptance of various polymeric materials based upon renewable resources. For instance the degree of degradation of thermoplastic corn starch (TPS) which was reinforced with natural fibres by 10, 15 and 20% wt. was after a fortnight in the same range as native corn starch. The flax fibre content exerts no significant influence on the degree of degradation since the deviations between the degradation slopes could hardly be resolved. However, TPS itself degrades significantly slower compared to the reinforced TPS-compound using flax fibres. This is because water can penetrate the reinforced material faster due to the “straw effect”. Hence this effect is only detectable above a certain level of fibre content. The degradation of the TPS was slower in these tests compared to the biodegradation of native starch which was due to the sample shape. Contrary to native starch (powder) TPS were used as pellets which results in a reduced specific surface to the TPS. Independent of the TPS-content (40 < ϕ_TPS < 70% wt) the PCL/TPS-blends degrade practically by the same speed as native starch. The TPU investigated in this report do not degrade significantly at temperatures between 20 and 37°C as long as the TPU is the sole carbon source. With the addition of a carbon source which can be easily degraded (e.g. corn starch) an increase of the TPU-degradation is detected. A rise of the test temperature (e.g. 70°C) speeds up the hydrolysis which drastically accelerates the biodegradation process. However intermediates may occur which can be toxic at high concentrations. Yet the toxicological impact of such intermediates shows a kinetic behaviour which could be demonstrated not only by using the OxiTop^®-System but also in accompanying toxicological tests.     

Preparation and characterization of the inclusion complexes between amylosucrase-treated waxy starch and palmitic acid

Amylosucrase-treated waxy corn starch (AS) was produced to extend the chain length of amylopectin to a great extent in comparison to its native chain length. An amylopectin–palmitic acid (PA) complex was prepared by heat-treating (121°C) a starch/PA mixture and its subsequent further incubation (95°C, 24 h); moreover, its structure and digestibility were studied. Unmodified waxy starch could not complex at all, whereas elongation due to amylosucrase modification allowed amylopectin to form a complex with PA to a small extent. Complexation between AS and PA caused a decrease in relative crystallinity. The AS–PA complex displayed an endothermic peak representing type I inclusion complexes rather than type II complexes. The formation of complexes did not significantly affect the in vitro digestibility maintaining the low digestibility of AS resulting from extremely small amounts of complexes and the type of complex.     

A Comparison between Corn Starch and Dry Milled Corn Products in their Dispersion Properties

Gelatinization of corn starch, flour, meal and grits has been compared. Amylograph curves show differences that can be related to particle size and to constraints on the swelling behavior, presumably due to native protein in the corn milled products. Autoclaving starch and dry milled products at 121 °C in the presence of steam alone merely hardens the particles. However, when the particles are in contact with liquid water, swelling and gelatinization readily occur and gels are formed. Above 10% loading, gels formed by autoclaved grits and meal are significantly more rigid than gels formed from corn starch alone. Flour gives gels of essentially the same properties as the starch up to 30% loading, above which flour gels become more rigid than starch gels and match the gels formed from corn meal and grits.     

Characteristics and application of octenyl succinic anhydride modified waxy corn starch in sausage

Native and acid‐hydrolyzed wx corn starches were modified by octenyl succinic anhydride (OSA) in aqueous slurry systems. The characteristics of the modified wx corn starches and their effects on chicken meat sausages were evaluated by means of FT‐IR, rapid visco analyser, SEM, and texture profile analysis. FT‐IR spectroscopy indicated that the ester carbonyl groups in the OSA modified native and acid‐hydrolyzed starches were characterized at 1725 cm⁻¹. The process of OSA modification could achieve starch derivatives, which had higher viscosities, better paste clarity and freeze–thaw stability than the native counterparts. Texture results showed that the hardness, springiness, cohesiveness, and chewiness of the sausage increased as OSA‐H0 was added (p < 0.05). SEM revealed that the sausages with native wx corn starch had larger and uneven pores, while it was comparatively compact for the sausages with OSA starches. The OSA modified wx corn starch offered a great potential to be used in meat products to enhance textural quality.     

Quantitative estimation of the action of α-amylase from Bacillus subtilis on native corn starch by HPLC and HPTLC

 The optimal conditions of corn starch liquefaction and dextrinization using α-amylase from Bacillus subtilis to obtain maltodextrins with a dextrose equivalent of 12.9–23.5 were determined. The pattern of action of B. subtilis α-amylase on native corn starch was monitored using high-performance liquid chromatography (HPLC) and high-performance thin layer chromatography (HPTLC). It was possible to separate malto-oligosaccharides of up to 9 glucose units by HPLC and those of up to 12 glucose units by HPTLC, respectively. The results suggest that α-amylase from B. subtilis is an endo-specific enzyme which mainly produces two oligosaccharides, DP3 and DP6. It was shown that both methods can be successfully applied for the characterization of maltodextrins. Received: 22 August 1997     

Effect of Acid Hydrolysis and Ball Milling on Porous Corn Starch

Porous corn starch from glucoamylase hydrolysis of native corn starch was examined before and after cross-linking, acid hydrolysis and dry ball milling. Cross-linking does not significantly change the crystallinity, water absorption or gelatinisation properties but acid hydrolysis at 60°C increases, proportionately, crystallinity and water absorption capacity and decreases moisture adsorption at humidities less than 80%, in comparison to untreated porous corn starch. Highly crystalline porous starch has a fragile granule structure. Ball milling destroys crystallinity in both normal, porous, and cross-linked or partially hydrolyzed starches. Particle sizes of 1–2m are obtained by milling dry starches for 48 h. Water absorption for milled starches is more than 200% (weight water/weight starch d.b.). Viscosities of these products were significantly reduced at high temperatures. Products formed stable gels in 25–30% dispersions in cold water.     

酸解对不同链/支比含量玉米淀粉特性的影响

以4种不同链/支比含量的玉米淀粉为原料,酸解处理不同时间,以酸解玉米淀粉的形貌特性、冻融稳定性、膨胀度、溶解度、晶体性质为指标衡量不同酸解时间对玉米淀粉结构性质的影响。结果表明:4种玉米淀粉酸水解程度的顺序为:蜡质玉米普通玉米淀粉G50G80。酸解后,同品种的4种玉米淀粉的析水率随着酸解天数的增加而增加;溶解度增加,膨胀度降低。酸解并未改变淀粉的晶型,随着酸解时间的延长,蜡质玉米淀粉和普通玉米的相对结晶度先增大后保持不变,G50和G80的相对结晶度随着酸解时间的增加而增大。表明酸解对低直链淀粉(蜡质玉米淀粉和普通玉米淀粉)的结构、性能影响最大。     

菠萝蜜淀粉-月桂酸复合物的理化特性研究

淀粉与油脂热加工过程中会产生大量淀粉-脂质二元复合物,这会显著影响淀粉基产品的品质、保质期、物理化学特性等.菠萝蜜是新型小颗粒、直链淀粉含量高的热带特色淀粉资源.以木薯和玉米两种淀粉与菠萝蜜淀粉同为A型结晶的淀粉作参照,探究加热过程中菠萝蜜原淀粉与月桂酸形成复合物的复合指数、糊化特性、粒径分布、颗粒形貌和短程有序性.实...     

Development and Physicochemical Characterization of New Resistant Citrate Starch from Different Corn Starches

Resistant starch has drawn broad interest for both potential health benefits and functional properties. In this study, a technology was developed to increase resistant starch content of corn starch using esterification with citric acid at elevated temperature. Waxy corn, normal corn and high‐amylose corn starches were used as model starches. Citric acid (40% of starch dry weight) was reacted with corn starch at different temperatures (120–150°C) for different reaction times (3–9 h). The effect of reaction conditions on resistant starch content in the citrate corn starch was investigated. When conducting the reaction at 140°C for 7 h, the highest resistant starch content was found in waxy corn citrate starch (87.5%) with the highest degree of substitution (DS, 0.16) of all starches. High‐amylose corn starch had 86.4% resistant starch content and 0.14 DS, and normal corn starch had 78.8% resistant starch and 0.12 DS. The physicochemical properties of these citrate starches were characterized using various analytical techniques. In the presence of excess water upon heating, citrate starch made from waxy corn starch had no peak in the DSC thermogram, and small peaks were found for normal corn starch (0.4 J/g) and Hylon VII starch (3.0 J/g) in the thermograms. This indicates that citrate substitution changes granule properties. There are no retrogradation peaks in the thermograms when starch was reheated after 2 weeks storage at 5°C. All the citrate starches showed no peaks in RVA pasting curves, indicating citrate substitution changes the pasting properties of corn starch as well. Moreover, citrate starch from waxy corn is more thermally stable than the other citrate starches.     

直链淀粉含量对淀粉-脂肪酸复合物形成及理化特性的影响

本研究以不同直支比的玉米淀粉和硬脂酸为原料制备了三种不同的淀粉-脂质复合物,并采用扫描电镜、X射线衍射、傅里叶红外光谱等分析方法对淀粉-脂质复合物外部形态、晶体结构、抗消化性、缓释性等进行了表征与测定。结果表明:在扫描电镜下观察,与原淀粉相比,复合物的体积增大,同时表面凹凸不平。红外光谱证明淀粉-脂质复合物的形成,同时氢键的增加可能会导致抗性淀粉含量增加。复合物的形成使得晶体构象变为V型结构。普通玉米淀粉（normal）及高直链玉米淀粉（G60）在处理后快消化淀粉（RDS）含量减少,慢消化淀粉（SDS）含量增加,抗性淀粉（RS）含量增加,其中抗性淀粉含量分别达到52.0%和52.4%。硬脂酸在复合物内的释放分为两个阶段呈现先快后慢的趋势,并且直链淀粉含量的增加能够显著提高复合物对于硬脂酸的缓释能力。本文可为进一步提高直链淀粉的应用范围提供参考依据。     

发芽对黑糯玉米淀粉特性的影响

将黑糯玉米进行发芽处理后，采用湿法提取工艺制得淀粉。比较发芽黑糯玉米淀粉与未发芽黑糯玉米淀粉的特性。结果表明：发芽处理后淀粉的颗粒保持原有的偏光十字结构；发芽处理后淀粉的溶解度和膨胀度变小；酸水解过程的前6d，发芽处理淀粉水解率比原淀粉大，之后水解率小于原淀粉；发芽处理淀粉糊的透明度高，抗凝沉性强，冻融稳定性好。淀粉性质的变化说明发芽处理使淀粉内部结构发生变化，特别是无定形区的直链淀粉的结合产生了不同稳定性的新的结晶。