Properties of Starch Obtained from Potato Tubers Influenced by Various Temperatures

The properties of starch separated from potato tubers were studied regarding the following storage temperatures: +20 °C, +8 °C, +4 °C and 0 °C. The study included also potato tubers having been frozen, thawed and refrozen as well as potato tubers before storage. Starch separated from the stored potato tubers showed differences in chemical composition, reducing power, granularity, whiteness and viscosity as well as gelatinization temperatures in comparison with the starch separated from potato tubers before storage. Quantity and direction of the changes within starch properties depended on storage temperatures. The smallest changes in the properties were observed during potato storage at +4 °C and +8 °C.     

Purification and Properties of Phosphoglucomutase from Potato Tubers

SUMMARY— The level of phosphoglucomutase in potato tubers has been found to be about 400 times higher than previously reported. This enzyme has been purified 40-fold over the dialyzed crude extract by a procedure consisting of fractionation with ethanol and acetone, fractionation with ammonium sulfate, and filtration through Sephadex G-100. The potato enzyme is similar to phosphoglucomutases obtained from other sources, but most closely resembles the rabbit muscle enzyme. It requires Mg²⁺ and cysteine for activity, is activated by preincubation with Mg²⁺ and cysteine, possesses a molecular weight of 63,000, exhibits optimal activity at pH 7.6, and is inhibited by anions.     

蜡质马铃薯淀粉性质的研究

研究了蜡质马铃薯淀粉的品质特性,结果表明:蜡质马铃薯淀粉糊液的黏度比马铃薯淀粉高,蜡质马铃薯淀粉糊化后不易老化,其糊液抗凝沉、透光度都优于蜡质玉米淀粉和糯米淀粉.用RVA测定了蜡质马铃薯淀粉糊在不同介质中黏度曲线的变化情况.     

马铃薯淀粉废水蛋白的功能特性

以碱提酸沉法制备的马铃薯淀粉废水蛋白为原料,分别考察了pH值、NaCl浓度和温度对蛋白功能特性（溶解性、持水能力、乳化性及乳化稳定性、起泡性及泡沫稳定性）的影响。结果表明,pH值、NaCl浓度和温度对蛋白的功能特性产生不同程度的影响。在等电点（pH 4.0）时,马铃薯蛋白表现出最低的溶解性、持水性、乳化性、乳化稳定性及起泡性,而泡沫稳定性最好。在较低NaCl浓度（＜0.2 mol/L）时,蛋白溶解性、持水能力、乳化性和乳化稳定性随NaCl浓度的增加而提高,而高浓度的NaCl（＞0.2 mol/L）对上述性质具有抑制作用;蛋白的起泡性和泡沫稳定性在NaCl浓度为0.4 mol/L时具有最大值。在4～80 ℃范围内,蛋白质的各项功能性质随温度的升高均呈现先增加后降低的趋势,且溶解性、持水性、乳化稳定性、起泡性及泡沫稳定性在40 ℃时最佳,乳化性在60 ℃最佳。     

蕉藕淀粉与薯类淀粉特性对比研究

为探索蕉藕淀粉应用范围,选取木薯淀粉、马铃薯淀粉、红薯淀粉等薯类淀粉为对照,对蕉藕淀粉与常见薯类淀粉的组成、吸水(油)率、溶解度、膨胀度、透明度、凝沉性、凝胶强度、冻融稳定性及黏度等特性进行了对比分析。结果显示:蕉藕淀粉与常见薯类淀粉特性相比除吸水性差异不显著外,吸油率、溶解度、膨胀度、透明度、凝沉性、凝胶强度、冻融稳定性及黏度变化均存在显著差异,可利用蕉藕淀粉直链淀粉含量高、透明度好、凝胶强度高等特性,开发新型淀粉食品和增稠稳定剂。     

Pasting Properties of Potato Starch and Waxy Maize Starch Mixtures

The pasting viscosity, morphological properties, and swelling properties of potato starch and waxy maize starch mixtures at different ratios were investigated. Pasting analysis of the starch mixtures (7% solids in water, w/w) using a Rapid Visco Analyser showed linear changes in peak viscosity and pasting temperature according to the mixing ratios of both starches, but not in breakdown and setback. The pasting profile revealed that the starches rendered mutual effects during pasting, more significantly when the amounts of potato and waxy maize starches were similar. The volume fraction of swollen granules and the presence of amylose appeared to be important parameters in the mutual effects of both starched during pasting. Under a light microscope, the swelling of potato starch granules was delayed by the presence of waxy maize starch. Overall results indicate that new pasting properties can be generated by mixing starches of different botanical sources.     

Chemical and Functional Characterization of Products Obtained from Yam Tubers

Aiming to find alternative uses of yam (Dioscorea alata) in the food industry, three products (flour, starch and mucilage) were obtained form yam tubers and characterized. Flours were obtained from peeled fresh tubers, dried at two different temperatures (30 and 55 °C) and then milled. Starch and mucilage were extracted from mashed yam before drying. Products were characterized by their chemical, structural, morphological, rheological and thermal properties. Flours showed differences in pasting, thermal and water absorption properties as a function of drying temperature. Starch contained 30% amylose. The analysis of monosaccharide composition of starch showed traces of mannose, xylose and rhamnose. The onset gelatinization temperature was 74.4 °C for starch, whereas those for flours varied between 71.5 and 74.4 °C. The relatively high gelatinization temperature and the absence of breakdown in the amylograph test evidenced the stable structure of starch when submitted to heat and shear. The mucilagenous material contained 55.36% protein and 43.05% starch, and also an acidic polysaccharide fraction linked to a neutral fraction. Flow curves of 1% mucilage dispersions showed a pseudoplastic behavior with high pH sensitivity. Results demonstrated that yam products have promising applications in the food industry.     

Crystallinity and Pasting Properties of Freeze‐Thawed High Amylose Maize Starch

Native and defatted high amylose (about 70%) maize starch gels were freeze‐dried or repeatedly freeze‐thawed, and the effects of the treatments on the crystallinity, pasting viscosity, and resistance to digestive enzymes of the dried starch were examined. Both native and defatted starches showed a B‐type crystal structure in the X‐ray diffractogram, but the crystallinity was decreased by repeating the freeze‐thawing cycle. In the DSC thermogram, the freeze‐thawed starches exhibited two endothermic transitions in the temperature ranges of 90—110 °C and 130—160 °C, representing amyloselipid complexes and amylose‐amylose double helix crystals, respectively. By defatting, the melting enthalpy for the amylose double helices was increased, indicating that the residual lipids inhibited the amylose crystal formation. Ice crystals in the starch gel matrix became smaller and the ice cell membrane became thinner as freeze‐thawing was repeated. The freeze‐dried or freeze‐thawed starch powders swelled to a paste by heating in water as did typical granular starch, but the setback by cooling was significantly high due to the rapid retrogradation of leached amylose. By the treatments, the resistance of the starch to digestive enzymes was also raised. The defatted starches displayed greater paste viscosity and resistance to digestive enzymes than the native starches. But the overall viscosity was decreased as the number of freeze‐thawing cycles increased.     

交联红薯羧甲基淀粉糊性质的研究

本文对交联红薯羧甲基淀粉糊性质进行了详细的研究,包括糊的冻融稳定性、抗生物降解能力、抗老化能力、糊透明度.同时研究了温度、pH值、剪切力及介质（蔗糖和NaCl）对糊黏度的影响.结果表明,交联红薯羧甲基淀粉糊冻融稳定性好,抗生物降解及抗老化能力强,透明度高;pH值、氯化钠强电解质对交联红薯羧甲基淀粉糊黏度影响较大.     

Comparative Study of Starch Fibers Obtained by Electro-spinning of Indigenous,Commercial and Cationic Potato Starch

ABSTRACT

By using the electro-spinning process on natural polymers, it is possible to obtain biodegradable membranes with potential applications in filters and scaffolds for tissue engineering. In this study, a comparison was made between the respective chemical, physical and thermal properties of the fibers from two sources of starch: One derived from a local, indigenous variety of potato (Diacol Capiro), native to the Boyacá region of Colombia (from here on referred to as “local starch”); the other, commercially available starch. A cationization of fibers was also carried out on the two starches. Chemical, physical and thermal properties were analyzed by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (DRX), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed the fibers were cationized with a highly amorphous state, with a heat resistance of 300°C from physicochemical changes generated in the fibers.     

Analytical Remarks to Explain Some Discrepancies in the Determination of Dry Matter and Starch from Potato Tubers Density

1) Air adsorbed on potato tuber surface can result the accidental error, decreasing the true value of tuber density. Some deviations from normal temperature do not seem to change substantialy the tuber density. 2) The dry matter determination should be precisely reexamined in a special series of experiments. The improper method can introduce a systematic error, increasing or decreasing the results. 3) It is necessary to compare mostly used methods of starch determination in potato tubers and to estimate the possible systematic errors. 4) The various slope of the regression line: dry mater/starch vs. potato density, can be resulted by different factors as follows: the variable intercellular spaces, the proportional systematic errors in analytical determination, the variable dry matter density, and increasing (or decreasing) value of non-starch substances. 5) The intercellular spaces can result either a constant or a proportional systematic errors in the tuber density determination. They can be eliminated by vacuum infiltration procedure, which should be, however, verified. 6) The dry matter determination seems to be difficult analytical problem and it has not been definitely solved until now. 7) The Maercker's constant has been until now an open question and its variability should be verified from analytical point of view.     

Viscoelasticity of Frozen/Thawed Egg Yolk

Dynamic rheological measurements indicate that the gel formed during freezing is based on physical aggregation rather than chemical binding, with a nonhomogeneous structure. The gelation was highly dependent on frozen storage temperature in the range -10 to 14°C, but there was no appreciable difference in the range -14 to 24°C. When yolk was maintained motionless and supercooled at -10°C and -12°C for 23 hr, no change in the complex modulus, G*, was observed, but there was a considerable increase when yolk was disturbed and became frozen at the same temperatures for the same time.     

Molecular Composition of Starches from Growing Potato Tubers

The changes in the molecular distribution of potato starch during the growth of tubers is determined by GPC (Sephacryl gel systems). After n-butanol fractionation of amylose and amylopectin an efficient statement of the molecular weight alteration of the starch components is observed. Amylopectin of young immature tubers shows a narrow highmolecular weight distribution whereas the amylopectin of mature tubers have a broader distribution with low- and highmolecular weight portions. Also the branched structure is different regarding starch of small and big tubers. Amylose shows a continous increase of the molecular weight. The range up to 0.2 · 10⁶ Dalton is diminished, the molecular weight range over 1.2 · 10⁶ Dalton is increased. The range in between rests nearly constant. These changes in the molecular composition are observed by different potato varieties, Conny and Sieglinde. Clear differences between the amyloses and amylopectins of these two varieties are noticed. The starch components of Sieglinde have always lower molecular weights as Conny starches, just so the overlapping range is much broader.     

羧甲基马铃薯淀粉的制备及性能研究

羧甲基马铃薯淀粉被广泛应用于工业部门。本文研究了水／异丙醇溶剂法制备高取代度马铃薯羧甲基淀粉，探讨了水分、温度、反应时间、理论取代度(DSt)、淀粉负荷以及氢氧化钠对一氯乙酸钠的摩尔比(nNaOH/nSMCA)对马铃薯淀粉羧甲基化过程的影响。用傅立叶变换红外光谱表征产物的结构，同时研究了羧甲基化过程对淀粉结晶结构的影响。     

乙酰化马铃薯微晶淀粉的制备及性能

为改善马铃薯淀粉性能,拓宽其应用领域,对马铃薯淀粉进行微晶化和乙酰化复合改性。本文以马铃薯淀粉为原料、盐酸为酸解剂、醋酸酐为乙酰化试剂、氢氧化钠为催化剂对乙酰化马铃薯微晶淀粉的制备和性能进行了研究。结果表明:马铃薯淀粉经微晶化及乙酰化后,其抗酸性、抗碱性和冷热黏度稳定性增强,但其凝沉性、冻融稳定性、蓝值和起始分解温度降低。马铃薯微晶淀粉结构为B型,乙酰化对马铃薯淀粉微晶结构有影响。     

Film Formation Properties of Potato Starch Hydrolysates

Native and freeze‐dried potato starch granules were partially hydrolysed to produce maltodextrins with dextrose equivalents (DE) 10, 15 and 20. Freeze‐drying greatly improved the enzyme accessibility of the native granules. Film formation properties of the hydrolysates were examined. Films were prepared by water casting. Especially the maltodextrins, which were produced from the native starch, were very sticky materials and could not form any films. But after removing most of the soluble saccharides from the maltodextrins, good quality films were produced by dissolving the hydrolysate in water, casting on a Teflon mould and drying the solution.     

甘薯抗性淀粉理化特性研究

选择3个不同类型甘薯品种,以提取获得的抗性淀粉为研究对象,通过X-射线衍射分析仪、差示扫描量热分析仪(DSC)、快速黏度测定仪(RVA)、紫外-可见吸收光谱仪、近红外光谱分析仪(NIRS)和扫描电镜等仪器分别对甘薯原淀粉和其对应抗性淀粉晶体结构类型、熔融温度、淀粉糊化特性、平均聚合度和淀粉分子结构等理化特性深入研究与分析。结果表明,不同甘薯品种间抗性淀粉熔融温度具一定差异,抗性淀粉与其原淀粉间糊化特性、晶体结构等特性呈明显差异。     

Some Physicochemical Properties of Amylose-free Potato Starch

In this paper some physico-chemical characteristics of amylose-free potato starch are described and compared to those from amylose containing potato starches. The availability of these high-amylopection or amylose-free starches has opened up new possibilities to assess the relationship between structural characteristics and physico-chemical properties of potato starch. At the same time it should be possible to determine more precisely the role of the amylose in the starch on several properties and characteristics. In all different analyses it was clear that amylose-free starch displayed unique properties. Not only was the response to heating much faster; it also occurred at much higher temperatures as demonstrated by viscographs, differential scanning calorimetry and swelling experiments. Rheological analyses demonstrated that gels formed from amylose-free starch were less rigid, smoother and shorter. The breaking of amylose-free gels furthermore required much less strength than that of amylose-containing gels. This aspect was also evident when threads were made from both starches; amylose-free threads were much shorter before breaking than threads made from amylose-containing starch.     

甘薯淀粉糊的流变特性

通过考察甘薯淀粉糊在不同甘薯淀粉浓度和不同温度下的流变特性,结果表明甘薯淀粉糊是典型的非牛顿型、剪切变稀的和触变性流体,温度越高,浓度越低,甘薯淀粉糊的滞后性越小;同时用幂律方程和Cross方程来描述糊的流变特性,发现Cross方程比幂律方程拟合精度更高。而浓度很低的情况下(如2%),甘薯淀粉糊的触变特性与其他浓度不同,表现为下行线在上行线之上,更适合用Herschel-Bulkley方程来描述它的流变行为。甘薯淀粉糊的动态流变行为则表现为在将开始糊化时,储能模量G’、损耗模量G"和tanδ都急剧上升,在到达糊化顶峰时急剧下降,而在降温过程中G’和G"都呈上升趋势,tanδ则是在100～50℃时下降,50～20℃时上升。     

马铃薯淀粉基质脂肪模拟物物理性质的研究

以马铃薯淀粉为原料,通过高温α-淀粉酶限制性水解的方法制备的脂肪模拟物,其物理性质较原淀粉发生了显著的变化。浓度为30%,DE值2～3之间的模拟物的凝胶强度、表观黏度较原淀粉都显著的降低,形成了具有类似脂肪口感的弱凝胶体系;另外还对DE2.5的模拟物的水溶性、持水性、玻璃化转变温度、冻融性等性质进行了研究并与原淀粉进行了对比分析,为其在低脂食品中的应用提供理论依据。