Starch Lipids and Their Effect on Rice Starch Properties

The properties of starch lipids and the effect of defatting on properties of starch granules from eight rice sorts were studied. Content of lipids associated with starch prepared by sodium dodecyl benzene sulfonate (DoBS) extraction of protein from rice flour ranged from 0.03 to 0.44%. Major lipids were free fatty acids and lysophosphatidyl choline. Major fatty acids were linoleic, palmitic, and oleic or myristic acid. Defatting reduced the gelatinization temperature and the gel viscosity of starch. Various methods of starch preparation were compared.     

非晶颗粒态玉米淀粉理化性质及消化性能的研究

非晶颗粒态淀粉是一种特殊的淀粉物态形式,具有颗粒性,但不具有结晶性。为了实现对原淀粉颗粒的改性,本文以玉米淀粉为原料,采用乙醇溶液处理法制备非晶颗粒态淀粉。在此基础上,研究了这种非晶化处理方法对玉米淀粉的颗粒形貌、结晶性质、溶解度与膨胀力及体外消化性能的影响。结果表明,原淀粉经非晶化处理后颗粒性仍保持完整,但颗粒表面有较大爆裂孔生成,并出现明显褶皱;非晶颗粒态玉米淀粉呈现V-型衍射结构,其结晶性基本消失,颗粒由多晶颗粒态结构转变为非晶颗粒态结构;与玉米原淀粉相比,其溶解度和膨胀度在相同的测定温度下均明显增加。原淀粉经乙醇溶液处理后,其快消化淀粉含量由92.83%下降到81.64%。而慢消化淀粉和抗性淀粉总含量由7.17%上升到18.36%。因此,采用乙醇溶液处理法对淀粉颗粒进行改性将有助于开发低热量和慢血糖应答的产品。     

Some Effects of Starch Lipids on the Thermal and Rheological Properties of Wheat Starch

Thermal and rheological properties of starches from two different wheat varieties were examined in relation to differences in surface distribution of lipids in the starch granules. The lipids present on the outside of the granules were extracted by isopropanol and the lipids in the amylose lipid complexes were extracted by water-saturated butanol. These amylose lipid complexes influence both the thermal properties of the starch, measured by differential scanning calorimetry, and the viscosity of the starch. The starch with the greatest amount of lipids extractable by water-saturated butanol began to gelatinize at a higher temperature and the gelatinization enthalpy was lower. Furthermore the viscosity began to increase at a higher temperature and the maximum viscosity was achieved at a higher temperature for this starch.     

LIPIDS OF WHEAT, CORN AND POTATO STARCH

The lipid constituents from wheat, corn and potato starches were analyzed, as was the composition of nonstarch compounds present in these lipid extracts. The lipids were extracted from starch granules using n- propanol-water (3:1, v/v) via cold and hot extraction into surface and internal lipid fractions, respectively; fatty acid profiles of the fractions so obtained were then carried out. The content of surface lipids was greatest from potato and wheat starches, whereas cornstarch was characterized as having the highest relative percentage of internal lipids. Hot extraction resulted in an increase in the lipid content for all extracts, and of the starches investigated, the lipids from cornstarch contained the highest percentage of polyunsaturated fatty acids. Unlike that of wheat starch, it was noted that the fatty acid, C20: 1 (n-9), could only be extracted from corn and potato starch granules by the hot extraction technique. Lysophosphatidylcholine (LPC) and some phenolics were found to bind to wheat starch granules, but not to those of corn and potato. Using HPLC-UV-DAD analysis, five phenolic compounds were detected in the lipids extracted from wheat starch by hot extraction. Maxima from UV-DAD spectra of the compounds were observed at a wavelength of 337.4 or 332.7 nm, and are characteristic of phenolic acids or their derivatives.     

挤压对小米蛋白溶解性和分子量的影响

本文研究了小米在不同温度和物料水分条件下挤压后各蛋白组分溶解性差异和总蛋白电泳图谱的变化.结果表明：挤压以后水溶性、盐溶性、醇溶性、碱溶性蛋白的含量明显减少.经不同条件挤压后,61.7%～78.9%的小米蛋白需用SDS和SDS＋2-ME才能提取出来,仍有13.2%～22.5%的剩余蛋白.随挤压温度的升高,水溶性、盐溶性、醇溶性蛋白含量增加,而碱溶蛋白的含量减少.SDS可提取蛋白含量随温度和水分的升高而减少,而SDS＋2-ME可提取蛋白含量增加.物料水分变化对蛋白质溶解性影响较小.电泳图谱显示,挤压以后小米蛋白高分子亚基含量减少.醇溶蛋白亚基通过二硫键交链,形成2条新的谱带.也存在蛋白质通过其它共价键交链的可能性.疏水作用和二硫键是导致溶解性降低的主要原因.     

Starch Lipids: A Reappraisal

It is proposed that lipids on the surface of starch granules should be called “starch surface lipids”, and that those inside the granules should be called “internal starch lipids”. Starch surface lipids appear to be derived from the “non-starch lipids” which are either free or bound to proteins in the starch-bearing tissues. In cereals the internal starch lipids are exclusively monoacyl lipids, and they are quite different in composition from the starch surface lipids and non-starch lipids. In some recent publications lipids purporting to be internal starch lipids evidently include substantial quantities of non-starch or surface lipids.     

豇豆淀粉的提取及理化性质研究

以长豇豆籽为原料,采用响应面Box-Behnken分析法优化淀粉提取工艺,并对其形态结构和理化性质进行表征。采用五因素三水平的响应面曲面分析法确定豇豆淀粉提取工艺最佳参数为:NaOH溶液的体积420 mL、浸泡时间17 h、乙醇的体积74 mL、振荡转速167 r/min、振荡时间70 min,此条件下理论提取率为62.13%。提取的豇豆淀粉灰分含量为0.17%,蛋白质含量0.87%,脂质含量0.25%,纤维素1.59%,溶解度0.73%,溶胀度1.85 g/g;扫描电镜图像表明,豇豆淀粉颗粒呈球型或椭球形,粒径大多分布在9~13 μm范围内;傅里叶变换红外光谱与X射线衍射分析分析表明,豇豆淀粉具有较强的结晶结构与相对结晶度,呈现典型C型结晶淀粉形态;热力学分析表明,起始糊化温度（T_o）为73.86 ℃,峰值温度（T_p）为80.59 ℃,结束温度（T_c）为88.53 ℃。结果表明豇豆淀粉具有紧密的空间结构与较强的抗糊化性质,在食品质构改良剂等领域有较好的应用发展潜力。     

Partial Leaching of Granule‐Associated Proteins from Rice Starch during Alkaline Extraction and Subsequent Gelatinization

Starch granule‐associated proteins, including granule‐bound starch synthase (GBSS), were found to be partially lost during alkaline extraction of rice starch. Variability in amount of loss of GBSS and other granule proteins was found among different rice lines. Also, part of the GBSS and other granule proteins leached out during gelatinization of the alkali‐extracted rice starch. Confocal laser scanning microscopy revealed that some protein still existed in gelatinized starch granules prepared from starch isolated using alkaline extraction. The starch that retained more GBSS and other granule proteins after alkaline extraction tended to have more protein in the isolated gelatinized starch granules, indicating that proteins resistant to alkaline extraction also tended to resist leaching during gelatinization. The study suggests that leaching of granule‐associated proteins may contribute to variations in paste properties of alkali‐extracted starches.     

Starch Granule‐Associated Proteins and Polypeptides: A Review

This paper reviews current information regarding the (non‐gluten) proteins which are naturally located in and on starch granules, and which are termed starch granule associated proteins (SGAPs). At least ten major SGAPs can be extracted from most starches and have molecular weights in the range of approximately 5 to 149 kDa. A substantial number of these proteins are located at the starch granule surface, where their presence in association with that of other minor granule components (such as lipids), appears to significantly influence the overall properties of both starch granules and starchy products. The different extraction conditions which can be exploited to selectively remove SGAPs are detailed. Although some SGAPs may serve as supplementary storage proteins, the majority of SGAPs are believed to be starch biosynthetic enzymes, a proportion of which remain trapped within the growing granule structure. The identity and quantities of the biosynthetic enzymes varies with botanical source, genetic variety and even with time. Current knowledge regarding the identities, compositions, locations, properties and functions of several of the more common SGAPs (e.g. the ∼15 kDa friabilin/puroindoline proteins, the ∼30 kDa protein, and the ∼60 kDa starch granule‐bound starch synthase (SGBSS) protein) are reviewed in detail.     

On the Possibility of Modifying the Gelatinization Properties of Starch by Lipid Surface Coating

The gelatinization properties of potato starch were modified by coating the surface of the starch granules with lipids by an aqueous dispersion of monoglyceride or an ethanol monoglyceride solution. The volumes of gels were smaller than those of the untreated starch. In the polarizing microscope it was observed that decreased disruption of starch granules in connection with gelatinization occurs with increasing amount of lipids present on the surface. The gelatinization enthalpy and the gelatinization temperature at a low water content measured by DSC (Differential Scanning Calorimetry) were not influenced by the lipid coating. A third endothermic transition, however, was observed for the lipid-coated starch. Freeze-drying, used in the preparation of the lipid-coated starch, was found to lower the gelatinization enthalpy as well as the gelatinization temperature.     

Wheat starch granule protein: The isolation and characterisation of a salt-extractable protein from starch granules

A salt-extractable protein has been isolated and purified from large (A-type) wheat flour starch granules (Triticum aestivum cv. Maris Huntsman). This protein was the major species extractable with NaCl and because of its ease of extraction it was tentatively concluded that it was associated with the surface of the granules. It had a molecular weight of approximately 30 000 as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE) and an isoelectric point (pI) in excess of 10 as judged by analytical isoelectric focusing in polyacrylamide gel. The amino acid composition of the protein was quite different from those of wheat gluten proteins. A protein with similar properties was present on small (B-type) Maris Huntsman starch granules and it could also be detected on A-type granules from another variety of hexaploid breadwheat (T. aestivum cv. Flinor) as well as on A-type granules from tetraploid durum wheat (T. durum). This protein was not present on starch granules prepared from germinated grains (Maris Huntsman). The protein had neither α-amylase activity nor inhibitory activity against either wheat or hog pancreatic α-amylases. Several other proteins could be extracted from A-type starch granules but only after gelatinisation of the starch granule in the presence of SDS. The electrophoretic behaviour of these proteins was quite different from that of the NaCl-extracted protein and the rigorous conditions required to separate the latter proteins from the starch granules suggested that they are internal components of the granules.     

Solvent Extraction of Fatty Acids from Amylose Inclusion Complexes

The extractability of palmitic and other common fatty acids from inclusion complexes with potato amylose was studied using a wide range of common lipid solvents. At ambient temperature negligible yields were obtained with light petroleum or diethyl ether, and yields were low with most other solvents except those containing methanol or water. At 100°C, methanol, ethanol and propanol and all alcohol-water mixtures gave good yields. Complexes of amylose with 1-O-palmitoyllysophosphatidylcholine also gave good yields when extracted with propanol-water (3:1) at 100°C. Since more rigorous conditions are required for extraction of lipids from native cereal starch granules, it seems that the barrier to lipid extraction is the structure of the granule rather than the resistance to lipid extraction of any possible inclusion complexes in the granules.     

茶多酚-高直链玉米淀粉共研磨混合物的制备与结构表征

为了提高抗性淀粉的含量,以茶多酚(TPs)和高直链玉米淀粉(HAMS)为原料,利用研磨技术制备茶多酚-淀粉共研磨混合物,通过X射线衍射、扫描电子显微镜和热重分析对其结构、形貌和热稳定性进行表征,并采用模拟体外消化方法对其营养片段(快消化淀粉、慢消化淀粉、抗性淀粉)进行评价。X-射线衍射表明,随着球磨时间的延长,所得共研物中淀粉的结晶衍射峰强度逐渐减弱,经3 h球磨的处理后,淀粉的结晶度由38.1%降低到8.3%。扫描电镜结果表明:淀粉颗粒膨胀,颗粒形状发生形变,表面变得相对粗糙,部分颗粒发生破裂,茶多酚与淀粉在共研磨过程中发生聚集粘连。热重分析结果表明,所得共研磨物较高直链玉米淀粉的稳定性低,但比茶多酚的热稳定性高。经共研磨处理后,当TPs与HAMS质量比由1:50增加到1:10时,所得共研磨物的抗性淀粉含量由6.31%±0.88%增加到31.92%±1.53%。经过共研磨处理后茶多酚-高直链玉米淀粉共研磨混合物的结晶度降低,形态发生变化,表面变得粗糙,颗粒黏连,热稳定性降低,抗性淀粉的含量增加。     

Lipid Composition of Field Pea (Pisum sativum cv Trapper) Seed and Starch

The total lipids in field pea seeds and refined starch were extracted by five aqueous/organic solvent systems and the greatest yield of total. neutral and polar lipids was obtained with hot n-propanol-water (3:1 v/v). Lipids extracted from field pea seeds represented 2.9% of the seed weight and consisted of 43.2% neutral lipids, 3.2% glycolipids and 53.6% phospholipids. The major components of the three fractions were 70% triacylglycerol in neutral lipid, 28% esterified sterol glycoside in glycolipid and 55% phosphatidylcholine in phospholipid. The purified starch fraction contained 0.22% surface lipids and 0.09% internal lipids. The surface lipids were primarily sterol esters and free fatty acids while only free fatty acids were found in the internal lipids. The ability of lysophospholipids and fatty acids to complex with field pea starch was demonstrated by differential scanning calorimetry and X-ray diffraction, respectively.     

响应面法优化酶法提取芋头淀粉工艺参数

采用碱性蛋白酶作为蛋白质酶解剂,对提取芋头淀粉的工艺进行研究。在单因素试验基础上,采用响应面设计优化提取芋头淀粉的工艺参数。结果表明：芋头淀粉酶法提取的最佳工艺参数为酶解时间137 min、酶用量0.9%、酶解温度41 ℃、pH 10,在此条件下芋头淀粉的实际提取率达88.92%。碱性蛋白酶法制得的芋头淀粉主要理化指标为蛋白质含量0.08%、白度94.45%、平均粒径1.23 μm。扫描电子显微镜图显示该提取方法未对淀粉颗粒造成损伤。     

紫薯花青素提取条件优化及淀粉等产物的制备

以‘紫罗兰’紫薯为原料,研究同步提取紫薯花青素以及制备紫薯淀粉、纤维素和紫薯蛋白的工艺及参数。紫薯与酸乙醇（pH 2）混合破碎、过滤、沉淀分离淀粉;将滤渣和分离淀粉后上清液混合,用微波辅助法提取花青素并优化提取条件;花青素提取液沉淀分离紫薯蛋白;提取花青素的滤渣制备紫薯纤维素。结果表明：微波辅助提取紫薯中花青素的最佳工艺条件为微波时间4 min、微波温度52 ℃、料液比1∶22.40（g/mL）、乙醇体积分数62%（pH 2）,在此条件下紫薯花青素的提取率（93.64±0.69）%、粗提物中花青素含量（9.58±0.20） mg/g。制备的紫薯淀粉质量分数（95.77±0.41）%、得率（占总淀粉质量分数）（73.06±1.03）%;滤渣粉中纤维素含量（117.11±2.69） mg/g;制备的紫薯蛋白中蛋白质含量（524.78±24.84） mg/g。该制备方法能够提高紫薯的利用率,降低生产成本。     

烤烟烟叶淀粉的提取工艺优化

为揭示烤烟淀粉的结构与特性,降低烤烟的淀粉含量,采用响应面分析法(RSM)对鲜烟叶淀粉的提取条件进行了优化。结果表明:烤烟烟叶淀粉提取最优条件为:亚硫酸浓度0.19%,液固比为7,浸提时间16 h;淀粉中脂肪含量为0.61%,蛋白质含量为3.73%,灰分为1.59%,直链与支链结构比例约为3∶7。     

A quantitative comparison of the extraction of protein fractions from wheat grain by different solvents,and of the polypeptide and amino acid composition of the alcohol-soluble proteins

Using several cultivars, whole milled wheat grain was first extracted with 0.5M NaCl to remove non-protein N, albumins and globulins: the amount of protein subsequently extractable by either 70% ethanol, 55% propan-2-ol, or 50% propan-1-ol (with or without the addition of acetic acid), was then compared. All solvents were tested at 4, 20 and 60°C both with and without the addition of 2-mercaptoethanol (2-ME) as a reducing agent. Raising the temperature, including a reducing agent, and repeated extractions, all combined to maximise protein extractability; least was extracted by 70% ethanol at 4°C and most by 50% propan-1-ol containing acetic acid and 2-ME at 60°C. The differing polypeptide compositions of these alcohol-soluble fractions illustrated why N solubility alone is not a sufficient guide to protein extraction, e.g. 35% of grain N was extractable by either 70% ethanol at 60°C or 70% ethanol containing 2-ME at 4°C, but high mol. wt polypeptides (>60000) were found only in the 60°C extract. In contrast, the complete range of alcohol-soluble polypeptides was extracted by all solvent mixtures based on propan-1-ol, even at 4°C. Amino acid analyses of these alcohol-soluble fractions confirmed the low levels of lysine in fractions free from high mol. wt polypeptides. More glycine was found in all fractions containing high mol. wt polypeptides, but only those extracted by propan-1-ol mixtures had an increased lysine content, the amount of which increased linearly as the extraction temperature was raised. Defatting the milled grain did not affect the extractability of alcohol-soluble proteins, but the amount of protein soluble in 0.5M NaCl decreased. The protein rendered NaCl-insoluble was not extracted by any of the alcoholic solvents tested, hence the N content of the residual material was increased. The inclusion of this denatured metabolic fraction in the residue will affect its amino composition. The problems arising from the retention of the classical nomenclature for Osborne-type fractions are discussed.     

Extraction with Ethanol as an Energy-Saving Alternative to Conventional Drying of Corn Starch

Drying of starch derived from corn wet-milling is an energy intensive operation in an energy intensive industry. An alternative to conventional drying involves extraction of water from the starch with an ethanol solution and reconcentration of the ethanol by distillation. Equilibrium data for starch with various concentrations of ethanol in water were obtained. These data were used to calculate the effect of multistage countercurrent extraction of mechanically dewatered starch using a mathematical model of the process. The energy required for drying the extracted starch and recovering the alcohol is predicted to be considerably less than that required for conventional drying. Energy savings up to 40% and more are possible.     

Amylographic Reproducibility of Defatted Potato Starch by the Re-Introduction of Lipid

It was tried to get the amylographic reproducibility of the defatted potato starch by the re-addition of the extracted lipid fraction in order to increase the knowledge on starch-lipid interaction. The starch was defatted with methanol, dried and passed through a 100-mesh-sieve. Then, 1.0% fatty acid as sodium salt was re-introduced to the defatted starch. The surface lipids as well as the internal starch lipids affect several physico-chemical properties, and the defatting treatment influences the starch granules with respect to morphological and qualitative changes. From the results was concluded that the characteristics of amylographic alteration were caused by the internal starch lipids present in small, but significant amounts, together with the starch surface lipids. From the industrial point of view it seems to be of importance, that the defatting treatment of potato starch leads to more viscose starch pastes.