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.     

Oxidation of Potato Starch by Hydrogen Peroxide

Potato starch was oxidized by hydrogen peroxide in alkaline and acidic reaction conditions with copper, iron and tungstate catalysts in order to introduce carboxyl and carbonyl groups to the starch molecule. Carbonyl contents up to 6.6 per 100 glucose units could be obtained, whereas carboxyl content remained low (up to 1.4). Starch yields in the alkaline and acidic reactions were 90 and 99%, respectively. The molecular weight decreased markedly with the degree of oxidation, and was dependent on the catalyst used. Rheological measurements revealed that when the molecular weight of the moderately oxidized starch was high, a very firm gel (G' = 40kPa) was obtained with 25% starch concentration. When the degree of oxidation increased, the storage modulus G' decreased. The more the oxidized starch contained carbonyl groups, the higher was the gelatinization temperature.     

Cationized Starch Derived From Pre‐Oxidized Starch For Textile Sizing and Printing

Maize starch was subjected first to oxidation using H₂O₂ in presence and absence of ferrous sulfate as catalyst and then to cationization using 3‐chloro‐2‐hydroxypropyl trimethyl ammonium chloride. A thorough investigation of the chemical and rheological characteristics of the oxidized starch and oxidized‐cationized starch samples was made. It was found that these modified starches display characteristics, which qualify them to function as excellent sizing agent and to less extent as thickeners for printing polyester fabric with disperse dyes. The differences among the oxidized samples prepared in acidic and alkaline media in presence and absence of ferrous sulfate with respect to carboxyl and carbonyl group content were explained on the basis of the different mechanisms involved in the oxidation reaction of starch. The amenability of the different oxidized starch samples to cationization and variation in the apparent viscosity after cationization of the oxidized starches were also reported.     

High Carbonyl Content Oxidized Starch Prepared by Hydrogen Peroxide and Its Thermoplastic Application

Hydrogen peroxide was used to oxidize gelatinized starch to oxidized starch (OS) with degree of oxidation (DO) ranging from 0.096 to 0.554 depending on the H₂O₂/starch molar ratios used. Then glycerol was added to OS to produce thermoplastic oxidized starches (TPOS). Titrimetric determination of carboxyl and carbonyl groups, FT‐IR, ¹H‐NMR and ¹³C‐NMR confirmed that at H₂O₂/starch molar ratios < 0.7, oxidized starch contained much more aldehyde than carboxyl groups, while at molar ratios up to 2.0, peroxide oxidation produced mainly carboxyl groups. Scanning electron microscopy (SEM) revealed that the oxidized starch particles (at DO 0.385) obtained a porous structure. The effect of DO on the structure and properties of OS, as well as mechanical properties and moisture resistance of TPOS was studied, respectively. With an increase in DO, the crystallinity, intrinsic viscosity and thermal stability of OS decreased markedly, the ability of OS to take up water decreased at low DO and increased at higher DO. These observations show that hydrogen peroxide can be used to oxidize starch in a controlled way. TPOS with DO 0.385 showed the best mechanical properties, its tensile strength was 6.1 MPa after placing in 100% relative humidity for 15 days.     

Hypochlorite oxidation of field pea starch and its suitability for noodle making using an extrusion cooker

The effect of hypochlorite oxidation on the Brabendar pasting properties of field pea starch and the suitability of native and oxidized starch for noodle making by extrusion cooking were investigated. Field pea starch was oxidized with sodium hypochlorite at a level of active chlorine ranging from 0.89 to 3.28% (starch db). The degree of oxidation was determined and expressed in terms of percentage of carboxyl and carbonyl groups, which ranged from 0.02 to 0.38% and 0.06 to 0.19%, respectively. Starch recovery and peak viscosity, hot paste viscosity, cool paste viscosity, and setback of oxidized starches decreased with increasing degree of oxidation. The cooking quality attributes of noodles prepared from native field pea starches were acceptable but were negatively influenced by hypochlorite oxidation. Substitution of potato starch (40%, db) for field pea starch yielded more glossy noodles with better cooking quality. It was also observed that Brabendar pasting properties had high correlations with noodle quality characteristics.     

Oxidation of Starch Catalyzed by Persulfate

Oxidation of unmodified corn starch in the presence of persulfates under different conditions has been studied. The method using silver catalyzed persulfate led to a grey colored oxidation product containing equal carbonyl but less carboxyl contents as compared to an industrial oxidized starch sample. Air-oxidation of starch in the presence of persulfate gave a colorless oxidation product possessing low carboxyl but high carbonyl contents. Irradiation, by ultraviolet light during this oxidation procedure had little effect on the degree of oxidation. Ammonium persulfate was found to be a better oxidant than potassium persulfate.     

小麦氧化-酯化淀粉的制备及其性质的研究

以醋酸酐为酯化剂,对小麦氧化淀粉进行酯化,研究酯化程度与反应条件的关系,测定粘度性质和结构特征.研究表明,反应体系pH、醋酸酐用量和氧化淀粉氧化程度的影响比较大.淀粉经氧化-酯化复合变性后,颗粒受到了更大程度的破坏,存在明显的酯羰基;复合变性后的淀粉更易糊化,糊的粘度有所降低,稳定性更好.     

Characterization of Different Starches Oxidized by Hypochlorite

The effects of starch origin (potato, corn, and rice starches) and hypochlorite level (NaOCl, 0.8% and 2% w/w) on the structures and physicochemical properties of oxidized starches were investigated. Carboxyl and carbonyl group contents of oxidized starches increased with increasing NaOCl level, with potato starch having the highest and corn starch having the lowest carboxyl groups content at both NaOCl levels. Oxidation generally reduced the pasting temperature and viscosity of native starches as demonstrated by using a Rapid Visco Analyser. The peak viscosities of oxidized rice and corn starches were higher than those of their native counterparts at 0.8% NaOCl. The morphology of starches was not altered and X‐ray diffraction patterns of all the starches remained unchanged after oxidation. Oxidized starch batters exhibited greater adhesions than did native starch batters, with rice starch batter exhibiting the greatest adhesion. Carbohydrate profiles by high‐performance size‐exclusion chromatography indicated that both amylopectin and amylose were degraded during oxidation. The level of oxidation was largely dependent on the degree of crystallinity of starch and the degree of polymerization of amylose, whereas the adhesion property of oxidized starch was mainly attributed to its granular size and shape.     

Physicochemical Properties of Oxidized Cassava Starch Prepared under Various Alkalinity Levels

The physicochemical properties of hypochlorite‐oxidized cassava starch as influenced by the alkalinity levels (pH 8 to 11) during modification process were investigated. Hypochlorite oxidation generally increased the contents of carbonyl and carboxyl groups in starch but decreased starch viscosity. The formation of carbonyl and carboxyl groups was more favorable under the milder alkaline conditions (pH 8 and 9). Oxidation conducted at higher alkalinity levels produced both functional groups at a much slower rate and to a lesser extent. Starch viscosity decreased markedly with increasing reaction time. The alkalinity levels during the modification process greatly influenced the initial viscosity of the oxidized starch paste and the viscosity stability of the paste during storage. Thermal behavior studies by differential scanning calorimetry (DSC) demonstrated that oxidation decreased both gelatinization temperature and enthalpy. The decrease in gelatinization temperature was strongly related to the carboxyl group content. The more carboxyl groups the oxidized starch contained, the lower was the gelatinization temperature. Retrogradation of amylopectin tended to increase slightly after oxidation. While the light transmittance of native starch paste drastically decreased during cold storage, the changes observed in oxidized starch pastes were less pronounced and appeared to depend on carboxyl content. The results from light transmittance studies suggested that carboxyl groups introduced into the starch molecules could effectively prevent retrogradation.     

变性淀粉的种类及其应用研究

本文较全面地综述了变性淀粉的种类及应用，尤其对深度氧化淀粉在制革中的应用作了综述和展望一通过几种不同的氧化方法相结合可以获得同时具有羧基和醛基的深度氧化淀粉。这种深度氧化淀粉在制革中可以用于分散纤维、选择填充或作为表面活性剂使用；同时可以与金属发生络合，制成絮凝剂而用于皮革废水处理，也可与金属结合鞣革，大量的醛基可以直接用于鞣革。因此，深度氧化淀粉具有广阔的应用前景。     

淀粉氧化程度与其表面施胶作用的关系

本文通过分析不同工艺条件下制备的氧化淀粉羧基含量、淀粉颗粒表面形态的变化，研究了不同氧化程度的氧化淀粉作为表面施胶剂对纸张性能的影响。结果表明，在本实验条件下，随着氧化剂（H2O2）、催化剂用量的增加，淀粉氧化程度提高；随着水用量的增加，淀粉氧化程度下降。作为纸张表面施胶剂，不同氧化程度的氧化淀粉对纸张性能的影响有明显的差别，其中，羧基含量为0．62％的2#及羧基含量为0．72％的6#氧化淀粉的作用效果最好。     

马铃薯氧化淀粉性质及其对哈尔滨红肠品质的影响

二氧化氯作为氧化剂制备马铃薯氧化淀粉,然后对其部分性质进行研究,并考察了添加马铃薯氧化淀粉对哈红肠品质的影响。马铃薯氧化淀粉的制备过程中,二氧化氯的添加量0.15%,LXF专用活化剂添加量为0.0125%,反应时间2.5h,反应温度35℃,在此条件下制备的氧化淀粉,其羧基含量0.1862%,羰基含量0.0548%,粘度15.69Pa.s,透光率19.23%,凝沉性0.647。由电镜扫描结果可知,马铃薯原淀粉经ClO2氧化后,淀粉表面变得较为粗糙,出现裂纹。红外光谱分析表明,体系中醇羟基的含量减少,而COO-含量明显增加。将马铃薯氧化淀粉添加到哈尔滨红肠中,通过质构分析发现红肠的硬度、弹性和咀嚼性明显提高。     

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.

     

荧光分光光度法测定淀粉及其衍生物中二氧化硫残留量研究

建立荧光分光光度法测定淀粉及其衍生物中二氧化硫残留量的方法。在弱酸性条件下,以邻苯二甲醛/铵盐为荧光指示剂,亚硫酸氢钠为定量标准,荧光强度作为考察指标,测定样品中的二氧化硫残留量。结果表明,标准曲线的线性回归方程为Y=23.22X+ 0.854,线性相关系数R2=0.999 8、检出限为0.732 mg/kg、加标回收率在95.3%～104.8%之间、精密度良好、检测结果可靠。荧光分光光度法可以作为淀粉及其衍生物中二氧化硫残留量的测定方法。     

臭氧处理对糯米品质的影响及其机理

采用质量浓度为5 mg/L的臭氧作为氧化剂,对糯米整米通气氧化后制作水磨糯米粉并且提取相对应的糯米淀粉。通过实验发现氧化后糯米粉及对应提取的糯米淀粉随着臭氧处理时间的增长糊化黏度呈增大趋势,但热糊稳定性和抗老化性有略许减弱,蒸煮特性未发生较大变化。羧基含量随着氧化时间的增长而增大,而羰基含量随着氧化时间的增长呈先增后减的趋势。通过红外光谱分析发现臭氧将糯米淀粉中葡萄糖单元上C2、C3和C6的羟基先氧化为羰基,随着氧化作用的加强羰基被氧化成为羧基,但由于是对于糯米的氧化处理,因此在反应中会生成部分酰胺,同时葡萄糖环中的C-O-C未发生断裂。     

碘量法测定EDTA铁碘盐的铁含量

对EDTA铁碘盐的铁含量测定做测定方法、测定条件和回收率的分析和探讨。在酸性条件下,三价铁离子可氧化碘离子,并游离出单质碘。以硫代硫酸钠标准溶液漓定,以淀粉显色为指示剂,可测定铁含量。实验表明用碘量法测定EDTA铁钠中铁的含量的方法是可行的。     

Binding of amino acids to hypochlorite‐oxidized potato starch

Novel starch derivatives were prepared by derivatization of oxidized potato starch with amino acids in aqueous suspension. Potato starch was oxidized using sodium hypochlorite and then reacted with amino acids under mildly alkaline conditions. By analysis of increased nitrogen content and by means of confocal laser scanning microscopy, efficient binding of positively charged amino acids to oxidized starch molecules was confirmed. A degree of substitution (DS) of up to 0.015 was obtained using oxidized starch (degree of oxidation (DO) of up to 1.0%) and positively charged amino acids (2–5%, dry starch basis) at reaction conditions of starch/water ratio of 1:2–2.5, pH 10, 40°C, 30–60 min. The DS was positively correlated with the DO of the starch. Derivatization of oxidized starch using amino acids generally enhanced the influence of oxidation on starch pasting characteristics, perhaps showing interesting functional properties and potential industrial application.     

Air-Oxidation of Starch Using Quinquevalent Vanadium as Catalyst

Air-oxidation of corn starch in the presence of ammonium meta vanadate at 35–40°C and pH 9 has been studied. The resulting oxidized starch contained more carbonyl but less carboxyl as compared to an industrial oxidized starch. However, the presence of undesirable amounts of the catalyst imparted extremely high viscosity to the oxidized starch. The ultraviolet irradiation was found to have a pronounced effect on the air oxidation of starch in the presence of ammonium meta vanadate. Increased carboxyl content was observed in the UV light catalyzed oxidized starch.     

钨酸在氧化淀粉制备中的催化作用研究

采用钨酸作催化剂、双氧水作氧化剂制备氧化淀粉,通过与不加催化剂双氧水氧化淀粉比较.发现羧基含量增加、黏度下降明显,证明钨酸对双氧水氧化淀粉有催化作用,并与硫酸铜、硫酸亚铁等成熟的氧化淀粉催化剂进行比较,发现钨酸对氧化淀粉的制备有催化作用,并且具有催化作用比较温和、氧化深度比较均匀、色泽较好等特点.分析了pH值、反应温度、催化剂钨酸加入量对钨酸催化制备氧化淀粉的氧化深度的影响,确定了钨酸催化制备氧化淀粉的较优工艺.     

Oxidation of cornstarch using oxygen as oxidant without catalyst

In the present work, oxygen was used as an environmentally friendly oxidant without catalyst, resulting in a waste free and simple method for starch oxidation. The oxidation was performed under the conditions of oxygen in sodium hydroxide at about 100 °C. It was found that the oxidation of the native cornstarch in this system depends upon the amount of sodium hydroxide, the temperature and the duration of the oxidation treatment. Twenty one gram NaOH, 100 °C and 3.0 h are the optimum conditions for getting the desirable water-soluble oxidized starch with carboxyl content of 3.6 g/100 g. The microstructure of oxidized cornstarch was characterized by scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR), Carbon-13 nuclear magnetic resonance spectroscopy (¹³C NMR) and chemical analysis methods. The results showed that the oxidation reaction introducing carboxyl and carbonyl groups took place at OH groups of C2, C3 and C6 in the glucose units and did not cause the breakage of C-O-C linkages.