The Oxidation of the Aldehyde Groups in Dialdehyde Starch

This paper describes the difference in relative reactivity of the aldehyde groups present in dialdehyde starch towards different oxidising agents. The oxidation of dialdehyde starch with peracetic acid and sodium bromide leads to only partial oxidation to give mono‐aldehyde‐carboxy starch, while oxidation with sodium chlorite results in dicarboxy derivatives. In order to obtain a more in depth insight into this phenomenon, the products obtained after partial oxidation via both routes were isolated and characterised. The results showed a pronounced difference in preferences between the two carbonyl groups towards the different oxidising agents.     

拟均相两段工艺氧化法制备双醛淀粉

以绿豆淀粉为原料,NaIO4为氧化剂的拟均相两段工艺制备双醛淀粉(dialdehyde starch,DAS),考察预处理阶段中温度、酶处理、超声活化和氧化阶段中反应温度、反应时间、pH值、投料比、NaIO4浓度、淀粉乳浓度、相转移催化剂对制备双醛淀粉的影响,前段的预处理采用超声活化处理,后段的氧化工艺考察相转移催化剂的影响,并用正交法对制备双醛淀粉的工艺进行优化。结果表明：在以醛基含量为考察指标,预处理时不宜用酶,处理温度50～60℃,经30℃、40W、40kHz超声活化淀粉乳30min能有效提高淀粉与NaIO4的氧化反应活性,制得高醛基含量的DAS。相转移催化剂对提高产品醛基含量有一定作用。经正交试验优化得到的最佳条件为：以十六烷基三甲基氯化铵为相转移催化剂、反应时间2h、反应温度40℃、n(NaIO4):n(淀粉)=1.0:1.0、NaIO4浓度0.5mol/L、淀粉乳质量分数10%、体系pH2,在此条件下,制得的DAS双醛含量为96.81%。经光谱和理化性能等指标的检测证实所得的DAS与文献报道的DAS相符合。     

Determination of the Carbonyl Groups in Oxidized Starches by Sodium Borohydride

A method of carbonyl groups determination in starches oxidized with nitrogen tetroxide or sodium has been modified. The carbonyl groups undergo the reduction with sodium meta periodate borohydride, added in known excess in alkaline medium. The unconsumed amount of hydride is then oxidized with sodium periodate in alkaline medium and unconsumed iodate determined iodometrically. A blank test is unavoidable. Standard deviation 0.106% and variation coefficient 6,960% were found from 10 determinations of carbonyl groups in a sample of starch treated with nitrogen tetroxide to low degree of oxidation. Similarly, standard deviation 0,802% and variation coefficient 3,290% of dialdehyde starch, oxidized to high degree of oxidation by sodium metaperiodate, were found.     

正交优化制备双醛淀粉研究

双醛淀粉毒性低,化学活性高,广泛用于各种工业,是一种很重要化工原料,但我国对双醛淀粉开发和生产还处于起步阶段。该研究以玉米淀粉为原料,高碘酸钠为氧化剂,采用正交优化法对制备双醛淀粉工艺条件进行研究;最佳工艺条件为:反应温度为35℃,反应时间为3.5小时,高碘酸钠浓度为0.5 mol／L,pH值为4.0,高碘酸钠与淀粉摩尔比为1.1:1。     

Modified Corn Starches with Improved Comprehensive Properties for Preparing Thermoplastics

A novel method of starch modification was developed to obtain thermoplastic starch plastics with improved comprehensive properties. Corn starch was oxidized under mild conditions using sodium periodate to prepare dialdehyde starch, which had an acceptable average molecular weight. The dialdehyde starch with 35.2% carbonyl content was reacted with different alcohols (methanol, ethanol, and glycol) to prepare a series of novel starch derivatives, whose structures were characterized by ¹H‐NMR and FT‐IR. The thermogravimetric analysis showed that these starch derivatives had an improved thermal stability compared with dialdehyde starch. Thermoplastic starch and its derivatives were prepared when water and glycerol were added as plasticizers. The modified thermoplastic starch and its derivatives had better mechanical properties than other modified starches, and lower humidity absorption than conventional thermoplastic starches. The highest tensile strength and elongation at break reached 17.5 MPa and 149%, respectively, and the highest humidity absorption was about 37%.     

双醛蜡质玉米淀粉的制备与特性研究

以蜡质玉米淀粉为原料,高碘酸钠为氧化剂,通过单因素实验,得到双醛淀粉制备的最优工艺条件:高碘酸钠与淀粉物质的量之比1.1:1,反应pH3.0,温度30℃,反应时间2h,淀粉乳浓度8%,得到的双醛淀粉中醛基含量为87.36%。偏光显微镜图片显示,样品醛基含量越高,偏光十字越少;通过红外图谱的表征,发现在波长为1729cm-1处出现明显的吸收峰,说明反应产物中有醛基存在;布拉班德粘度曲线表明,双醛淀粉的起糊温度比原淀粉高,峰值粘度随氧化度的升高而降低;X-射线衍射图谱表明,强峰吸收随着醛基含量的升高而消失,说明淀粉的结晶结构被破坏。     

纳米银/纳米二醛纤维素气凝胶的制备及表征

使用漂白硫酸盐针叶木浆为原料,以经高碘酸钠氧化后制备出的二醛纤维素为基材负载纳米银颗粒,后经高压均质法得到载银量为24.78%的纳米银/纳米二醛纤维素气凝胶。探讨高碘酸钠氧化反应时间对构成漂白硫酸盐针叶木浆的纤维素大分子以及针叶木纤维的影响。通过傅里叶变换红外光谱仪、X射线衍射仪、紫外可见分光光度计、扫描电子显微镜、透射电子显微镜和比表面积和孔径分析仪对样品进行表征。结果表明,随着氧化时间的增加,纤维素的醛基含量持续上升,当反应4 h时增至330 μmol/g,纤维的聚合度由1447大幅下降至525,同时零距抗张强度和长度也呈现下降趋势。制备出的载银气凝胶上负载的纳米银颗粒为球形,气凝胶的比表面积为35.40 m~2/g,平均孔径为19.62 nm。     

Transformations of Potato Starch During Oxidation with Hypochlorite

Five starch samples of different degree of oxidation were obtained with the help of sodium hypochlorite. Apart from that, commercial starch was divided into 3 fractions of differentiated size of grains and the fractions were also subjected to oxidation. The analysis of oxidized starch led to following results:

• large grains of starch undergo the oxidation process more easily than small grains, from oxidized starch hydrolysates glucuronic acid amounting to about 75% of carboxyl groups and gluconic acid to about 25% of carboxyl groups, can be separated;
• side reaction proceeding during oxidation process is hydrolytic degradation of starch molecules which is shown by the increase of reducing value and the decrease of viscosity of oxidized starch;
• in starch oxidized with hypochlorite absence of dialdehyde systems is characteristic in contrast to starch oxidized with periodate;
• in the process of oxidation with hypochlorite, starch molecules change their shape and spatial system, which is indicated by the changes of colour complexes with iodine, greater resistance to the action of amylolitic enzymes and greater capacity for forming flexible gels in the form of films.

     

Structural and Physicochemical Changes of Potato Starch Along Periodate Oxidation

Dialdehyde starches were prepared by oxidation with periodate. The influence of the degree of oxidation of the dialdehyde starch on its microstructural and physicochemical properties such as crystallinity, granular structure, complexing capacity with iodine and lysolecithine and water absorption are discussed. Oxidation appears to cause a gradual decrease of any microstructure, meanwhile water absorption is observed to be maximal at intermediate degrees of oxidation. A structure-swelling relationship has been developed and compared with the washing efficiency during purification.     

Preparation and Calcium Complexation Properties of a Series of Oxidized Polysaccharides. Structural and Conformational Effects

A number of polysaccharides of the starch type, including maltodextrins and cyclodextrins and some other well-known polysaccharides have been oxidized by periodate/chlorite (two-step method) or hypochlorite (one-step method), yielding ring-opened polycarboxylates. The oxidation products from the starch type show by far the best calcium complexing properties and have potential application as phosphate substitutes in detergent formulations. A relatively sharp increase in calcium complexing ability is observed at a degree of polymerization of about ten, whereas just a slight further improvement occurs at higher degrees of polymerization. This phenomenon is explained by the formation of helix structures which contain efficient Ca(II) complexing sites. This idea is supported by ¹⁷O NMR measurements showing that oxidized starch type compounds with m > 10 behave as heptadentate ligands.     

Oxidation of Maize and Rice Starches Using Sodium Chlorite Along with Formaldehyde

Maize and rice starches were independently oxidized with sodium chlorite in absence and presence of formaldehyde. The treatment was carried out under different conditions including sodium chlorite and formaldehyde concentrations and duration. Since the treatment involves degradation of starch via oxidation, the treated starch samples were monitored for carboxyl and carbonyl contents as well as apparent viscosity at different rates of shear. Results obtained indicated that with both starches the percent chlorite decomposed increases as the formaldehyde concentration increases within the range studied (0.0–0.3 g/100 starch). The same holds true for the duration of oxidation (15–90min). The apparent viscosity of starch before and after oxidation decreases as the rate of shear increases. Maize starch is more susceptible to oxidation than rice starch. When applied as sizing agents for cotton textiles oxidized starches derived from maize and rice starch display better performance than the unoxidized starch but with the superiority of the sizeability and desizeability of oxidized maize starch.     

Chemical Process for Making Dialdehyde Starch

A practical, strictly chemical process has been developed for the periodic acid oxidation of starch to dialdehyde starch. In the procedure spent oxidant is converted by alkaline hypochlorite to insoluble sodium paraperiodate, which is recovered in high yield for recycling. The process is suitable for small-scale production of dialdehyde starches of various carbonyl contents.     

Preparation and Calcium Complexation of Oxidized Polysaccharides. Part I: Oxidation of Maltodextrins and Starch with Alkaline Sodium Hypochlorite

The oxidation of maltodextrins and starch with aqueous alkaline sodium hypochloride has been studied. At an oxidant level of 3 moles hypochlorite per anhydroglucose unit at pH 8–9, a C2, C3-glycol-cleaved dicarboxy polysaccharide was obtained containing up to 45% ring-opened glucose units. Hydrolysis of the oxidation products yielded (apart from glucose) erythronic and glyoxylic acids, but no glucuronic acid evidencing the absence of C6-oxidation. The average degree of polymerization of the products ranged from 14 to 87 and indicated severe chain degradation during the oxidation. The products were shown to be effective calcium complexing agents and behaved as regular polyelectrolytes with identical complexing sites.     

双醛淀粉湿强剂的合成

研究了以木薯淀粉为原料、以高碘酸钠为氧化剂合成双醛淀粉的工艺条件，通过对不同氧化度双醛淀粉的红外光谱和结晶研究，对制备DAS的反应进程进行了探讨，结果表明，根据需要可制得不同氧化程度的双醛淀粉，与原淀粉相比其物理和化学性质都发生了很大的变化。     

淀粉醛强化大豆分离蛋白/槲皮素复合膜制备及性能研究

目的 探究淀粉醛(dialdehyde starch,DAS)对大豆分离蛋白(soy protein isolate,SPI)/槲皮素(quercetin,QR)复合膜特性的影响。方法 以青稞淀粉为原料,通过高碘酸钠氧化制备了DAS,以SPI为基质,以DAS和QR为添加物,以拉伸强度、水分阻隔性能、抗氧化性能为指标进行单因素试验,通过响应面优化试验筛选出DAS强化的SPI/QR复合膜最佳制备条件后,对复合膜的微观结构进行表征,并对其物理学性能进行测试。结果 DAS强化的SPI/QR复合膜最佳制备条件为每100 mL蒸馏水中添加SPI 6.00 g、pH为8、DAS 5%、QR 4%、DES 25%(DAS、QR、DES以SPI质量计)。在此条件下,薄膜的拉伸强度为(7.37±0.39) MPa、水蒸气透过系数为(3.54±0.29)×10^-11 g/(m·s·Pa)、抗氧化活性为(70.88±0.40)%。结构表征结果表明, DAS的添加使得该复合膜分子间形成了共价亚胺键,表面结构及横断面结构更加致密。此外,该复合膜具有较好的热稳定性、紫外阻隔性、疏水性。结论 D...     

Dialdehyde starches and their hygienic evaluation]

The paper carries some information on modified starches. Tests were staged on albino rats (males and females) to investigate samples of maize dialdehyde starches with the degree of oxidation of 0 (control), 5, 10 and 25 per cent. For 20--25 days the animals were fed on a synthetic diet in which the whole of the starch was replaced with the dialdehyde starch. As demonstrated, the 25% oxidation starch produced an adverse effect on the rats, viz. the animals lagged in the weight gain, suffered from diarrhea and the content of the intestinal enzymes was below that in controls. Feeding of the rats on starch with a lower degree of oxidation was attended by retardation in weight but did not produce any noticeable functional intestinal disorders.     

Changes in the chemical and functional properties of protein fibers by reaction with carbonyl compounds. Part II. Reaction of arginine and amido groups. Quantitative determination of reacting carbonyl groups

The arginine content of Vicia faba protein/casein(1:1)-fibers is made to decrease up to 50 per cent by reaction with glyoxal and up to 15 per cent by dialdehyde starch. Formaldehyde and glutaric dialdehyde do not influence the arginine content. The content in amido groups is not affected by the reaction with glyoxal, dialdehyde starch, formaldehyde, and glutaric dialdehyde. The reaction of the fiber protein with the quoted aldehydes increases in the following order: glyoxal < formaldehyde < dialdehyde starch < glutaric dialdehyde and is dependent on the concentration of the specific aldehyde.     

Effects of Osmotic Pressure on the Crosslinking Reaction of Tapioca Starch

Tapioca starch was crosslinked with 0.1 % sodium trimetaphosphate (STMP) in the presence of alkali and of osmotic pressure enhancing salts such as sodium sulfate and sodium chloride. The addition of various percentages of sodium sulfate to the crosslinking reaction mixture changed the pasting properties of the product starch as measured in the RVA (Rapid Visco Analyser). Peak viscosity (PV) and final viscosity (FV) are first increased with the increase in osmotic pressure followed by a decrease of the viscosities after further pressure increase. Breakdown (BD) is decreased in line with the increase of the osmotic pressure with very good correlation (R² = 0.96). These pasting characteristics are attributed to the inhibited swelling without disruption of the starch granules due to the crosslinking reaction. If sodium chloride is used as an osmotic pressure enhancer of the crosslinking reaction, both pasting properties (PV, FV) decrease linearly with the increase in osmotic pressure with very good correlation (R² = 0.98 and 0.99, respectively). The BD is dramatically decreased to zero (no breakdown) after applying the osmotic pressure and remains zero after further increase in osmotic pressure. These properties are also attributed to the pasting characteristics of the crosslinked starch. The increase in pasting temperature (PT) with increasing osmotic pressure for both sodium sulfate and sodium chloride demonstrates the increase of the gelatinization temperature of the starch granules. The enhancement of the osmotic pressure can promote the activity of the crosslinking agent.     

Scanning Electron Microscopy of Chemically and Enzymatically Treated Black Gram (Phaseolus mungo) and Ragi (Eleusine coracana) Starch Granules

Amylolysis of chemically - treated starch granules of black gram and ragi was followed colorimetrically and by scanning electron microscopy. From the percent hydrolysis values it was evident that oxidation with periodate resulted in considerable resistance, whereas urea treatment resulted in granule susceptibility towards in vitro amylolysis. The action of α-amylase and/or glucoamylase on periodate oxidised black gram starch showed on SEM sufficient enlargement of the granules and hollow craters as well; whereas similar treatment on oxidised ragi starch resulted in folded, distorted and deformed granules. Treatment with 8M urea resulted in the total loss of characteristic granular shape and formation of the socalled amylopectin “sacs”. Like waxy starches the latter showed an increase in enzymic activity. Particularly, the synergistic action of α-amylase and glucoamylase on ureatreated starches virtually collapsed the granules, forming innumerable “flat” ribbon like fragments.     

氧化淀粉的理化性质和结构表征

淀粉是一种可再生资源，近年来淀粉在皮革上的应用和研究已经越来越受到重视。该实验通过双氧水和高碘酸钠两次氧化合成了一种同时含羧基和醛基的氧化淀粉，并且对该合成氧化淀粉进行了理化性质分析和结构表征，包括固含量、pH值、羧基、醛基和羰基含量的测定，利用红外和凝胶色谱进行了结构分析，有利于制革中的应用。