Effect of hydroxypropylation on physical and rheological properties of sweet potato starch

Sweet potato starches (SPS) were hydroxypropylated to evaluate the effect of molar substitution (MS, 0.042-0.153) on the rheological properties, thermal properties, freeze-thaw stability, paste clarity, and gel strength of hydroxypropylated sweet potato starches (HPSPS). The swelling power and solubility values of HPSPS were higher than those of native sweet potato starch (SPS) and increased with an increase in MS. The transition temperatures (T_o, T_p, and T_c), and enthalpy (ΔH) of gelatinization of HPSPS were lower than those of native SPS, and significantly decreased with an increase in MS.Rheological properties of HPSPS pastes were measured under the conditions of steady and dynamic shear. Their consistency index (K), apparent viscosity (η_a,100), Casson yield stress (σ_oc), complex viscosity (η*), and dynamic moduli (G′ and G″) values decreased with an increase in MS, while their flow behavior index (n) and tan δ (ratio of G″/G′) values increased. The dependence of apparent viscosity on temperature followed the Arrhenius model for all samples. The paste clarity of HPSPS paste was more pronounced with increasing MS of hydroxypropyl groups. The HPSPS gels showed lower gel strength and also better freeze-thaw stability with a significant decrease in syneresis (g/100 g) compared to native SPS.     

交联作用对合成交联羟丙基木薯淀粉的影响

以合成的羟丙基木薯淀粉为原料，三偏磷酸钠为交联剂研究了交联作用对合成交联羟丙基木薯淀粉的影响，并探究了羟丙基木薯淀粉黏度与取代度、交联羟丙基木薯淀粉黏度与交联度之间的关系。     

Physicochemical properties of sweet potato starch

Tropical root crops, of which the sweet potato is an important representative, constitute an under exploited resource of developing countries. They can be used as food for both human and animal consumption and their starch is a source of industrial raw material. This review will consider recent reports on sweet potatoes, the physicochemical properties of their starches in comparison with other starches, and the possible causes of variation in these characteristics.     

Phase transition of cross-linked and hydroxypropylated corn (Zea mays L.) starches

The thermal behaviors of three chemically modified starches (cross-linked waxy corn, hydroxypropylated regular corn, and hydroxypropylated and oxidized waxy corn) were studied using light microscopy, SEM, DSC, XRD, and HPSEC. During the gelatinization process, molecular and crystalline order losses occurred independently from each other. Oxidation treatment altered the effects of hydroxypropylation on starch gelatinization. Both cross-linking and hydroxypropylation tended to preserve granular crystalline order during initial stages of gelatinization. The crystallinities and X-ray patterns of each starch remained essentially unchanged prior to phase transition.     

氧化交联甘薯淀粉的性质研究及结构表征

采用氧化交联对甘薯淀粉进行改性处理,提高了淀粉的白度,改善了淀粉糊的稳定性和抗老化性,并对改性淀粉的结构进行表征。研究结果表明:淀粉变性后,淀粉糊冻融稳定性提高,凝沉性减弱,抗老化性能较强;变性淀粉粘度变化较小,且具有较好的耐酸性能,但是耐碱性较差;具有很好的抗剪切性;抗酶解性能增强。氧化交联乙酰化己二酸双淀粉酯在1729cm-1处产生了新的吸收峰,并确定该吸收峰为酯羰基的伸缩振动峰。利用扫描电镜和X射线衍射分析,表明甘薯淀粉的改性没有改变其晶体结构,交联反应基本发生在淀粉颗粒的无定形区。     

精制甘薯淀粉的生产技术

采用去皮工艺,控制沉降的温度和pH值,在破碎的同时加入0.005％抗坏血酸和0.005％亚酸酸钠,生产出精制甘薯淀粉,其白度达到88.80。     

薯类通心粉丝机的研究

介绍了６ＴＦ－３０型薯类通心粉丝机的结构特点,确定了其主要参数,对粉丝机头模具设计进行了分析,最后给出了性能测试结果和整机参数。     

甘薯方便粉的加工工艺

以甘薯淀粉为主要原料,经过净化脱色、挤压糊化和干燥成型等工序后,附加不同口味调味料包,制成方便薯粉。     

Antimicrobial and physical properties of sweet potato starch films incorporated with potassium sorbate or chitosan

Antimicrobial biodegradable films have been prepared with sweet potato starch by incorporating potassium sorbate or chitosan. Films incorporated with potassium sorbate ≥ 15% or chitosan ≥ 5% were found to have an anti-Escherichia coli effect. Staphylococcus aureus could be effectively suppressed by incorporation of chitosan at ≥10%. Whereas potassium sorbate lowers the tensile strength and elongation at break, and raises the oxygen permeability, water vapor permeability and water solubility, chitosan has the opposite effect. Fourier Transform Infrared (FT-IR) spectra analysis revealed that starch crystallinity was retarded by potassium sorbate incorporation and that hydrogen bonds were formed between chitosan and starch. This explained the modification of the mechanical and physical properties of the films by the incorporation of these two antimicrobial agents.     

食用交联甘薯淀粉制备与性质研究

以甘薯淀粉为原料,三偏磷酸钠为交联剂,对甘薯淀粉进行变性,制备食品用交联甘薯淀粉。以交联淀粉峰值粘度和结合磷含量为指标,以三偏磷酸钠用量、反应pH、温度、时间和硫酸钠用量为因素研究交联反应最优工艺;并研究系列食用交联甘薯淀粉粘度、溶解度、膨胀度、透明度、凝沉性、冻融稳定性等理化性质及形态学和结构性质,为其在食品中应用提供理论依据。     

甘薯交联抗性淀粉热力学性质与消化性研究

根据膨胀度、糊化度及差示扫描量热仪(DSC)测得热力学参数,综合分析甘薯交联抗性淀粉和原淀粉热力学性质,并采用Jenkins提出In–vitro模型测定淀粉体外消化性。结果表明:在同一温度下,甘薯交联抗性淀粉膨胀度和糊化度均较原淀粉低,且交联剂用量越高,淀粉膨胀度和糊化度越小;DSC测试结果显示,甘薯交联抗性淀粉相转变温度To、Tp、Tc随交联剂用量增加而升高,Tc–To和△H均比原淀粉低。In–vitro消化模拟实验表明,甘薯交联抗性淀粉消化性比原淀粉低,并随交联剂含量增加,消化产物量减少,消化速度降低。     

一步和二步改性法对交联酯化甘薯淀粉性质的影响

以三偏磷酸钠(STMP)为交联剂,醋酸酐为酯化剂,对甘薯淀粉进行复合变性,通过一步和二步改性法制备交联酯化改性甘薯淀粉。比较了一步和二步改性法对交联酯化甘薯淀粉性质的影响。一步法指甘薯淀粉交联后调整酯化的条件,省去水洗、中和与干燥操作工序连续进行酯化;二步法为将制备的交联淀粉粉碎干燥后作为酯化变性反应的原淀粉。以峰值粘度和稳定性为指标测定。结果表明:一步法改性的交联酯化甘薯淀粉具有更好的峰值粘度和稳定性;二步法改性的交联酯化甘薯淀粉具有更好的抗凝沉性,溶解度和膨胀度略高于一步法,抗冻融性更好,但与一步法差别不显著。     

Physicochemical characterization of sweet potato starches popularly used in Chinese starch industry

Physicochemical properties of starches isolated from 11 sweet potato cultivars popularly used in Chinese starch industry were studied. Moisture, protein, ash, lipid and phosphorus content of the starches varied from 3.86 to 6.52%, 0.28 to 0.75%, 0.10 to 0.47% and 0.00 to 0.02%, respectively. Amylose content varied between 13.33 and 26.83%. The starches differed in their mean granule sizes, particle size distribution, and susceptibility to pancreatin hydrolysis. Swelling power and solubility ranged from 13.46 to 26.13 g/g and 8.56 to 18.77%, respectively. Higher retrogradation tendency was observed in pastes of starches of high amylose content. Gelatinization temperature and enthalpy ranged from 55.54 to 69.11 °C and 6.40 to 11.89 J/g, respectively. Pasting properties including peak viscosity (134–255 BU), breakdown viscosity (91–162 BU), setback viscosity (26–112 BU), peak time (5.97–7.03 min) and pasting temperature (67.20–73.00 °C) varied significantly among the sweet potato starches. Pearson's correlation analysis showed that phosphorus content of the starches had substantial effect on their swelling power (r = 0.70, p ≤ 0.05) showing positive correlations. There was significant positive correlation between swelling power and solubility of the starches (r = 0.64, p ≤ 0.05). Thermal and pasting parameters also showed significant correlations.     

甘薯淀粉性质的研究

研究了甘薯淀粉的理化性质,结果表明:其颗粒粒径的平均值为5~31mm,结晶结构属C型,直链淀粉含量18.5%,糊化温度为60.8~78.5℃。甘薯淀粉的透明度为42%,凝胶强度为98g。     

红薯淀粉水凝胶制备及吸水特性研究

以红薯淀粉为原料,以4-二甲基氨基吡啶为催化剂,于水相中经过醋酸酐酯化处理制备红薯淀粉水凝胶。确定了制备红薯淀粉水凝胶的最佳工艺条件,红外光谱确认在淀粉中引入了羧甲基。红薯淀粉水凝胶吸水性增强,黏度增大,糊透明度得到改善,说明红薯淀粉水凝胶具有优良吸水特性。     

掺假藕粉中木薯淀粉和甘薯淀粉的鉴别-差示扫描量热法

为了对掺入藕粉中的其他淀粉种类进行鉴别,本研究通过差示扫描量热仪对藕粉等常见几种淀粉的糊化过程进行考察发现,藕粉与其他淀粉在糊化吸热峰上有着明显的差别。根据藕粉与木薯淀粉和甘薯淀粉等在糊化吸热峰上的差异,以糊化吸热峰作为特征指标,对掺假藕粉中掺入的木薯淀粉和甘薯淀粉进行定性或定量鉴别实验。同理,此方法也可用于检验与藕粉在糊化吸热峰上有明显差异的用于藕粉掺假的其他淀粉种类,如马铃薯淀粉,玉米淀粉等。此方法将弥补前期发表的基于淀粉颗粒超微形貌特征的可食用淀粉种类扫描电镜鉴别方法的不足。     

甘薯淀粉磷酸单酯的制备及其微观结构的研究

以甘著淀粉为原料与混合正磷酸盐作用,采用湿法工艺制备甘薯淀粉磷酸单酯。利用五因素二次正交旋转组合试验法研究了淀粉磷酸单酯制备的工艺条件并得出回归方程,直观地揭示了取代度与诸因素之间的数量关系。结构分析表明,酯化反应影响了淀粉分子的结晶区域,在淀粉脱水葡萄糖单元羟基上引入了磷酸基因。     

干燥工艺对甘薯淀粉回生率影响

以甘薯淀粉为原材料,以甘薯淀粉回生率为指标,研究常温、太阳晒、真空减压、干燥箱和微波干燥等不同干燥工艺对甘薯回生抗性淀粉生成率影响。结果表明,各干燥最佳工艺参数为:常温下大气温度为16℃～19℃、大气湿度为68%～80%时,老化后甘薯淀粉5 d达至恒重,回生率由3.5%提高到4.5%,提高28.5%;阳光照射下,大气温度为23℃～36℃、大气湿度为42%～74%时,老化后甘薯淀粉5 d达至恒重,回生率由3.5%提高到4.7%,提高34.2%;真空干燥箱温度为120℃、真空度为0.08 MPa时,甘薯淀粉回生率最大,为14.62%,比空白提高3.1倍;干燥箱温度为90℃时,甘薯淀粉回生率最大,为12.24%,比空白提高2.5倍;微波温度为45℃时,甘薯淀粉回生率最大,为7.12%,比空白提高1倍;相比之下,真空干燥有利于甘薯淀粉回生。     

The relationship between entanglement concentration and physicochemical properties of potato and sweet potato starch dispersions

Entanglement concentration (c_e) is defined as the onset of overlap and interpenetration of random‐coil chains in a polymer solution and is important in determining rheological, dynamic and fracture properties. However, few studies have reported in detail how c_e influences physicochemical properties of starch dispersions. So, the effects of c_e on the physicochemical properties of the potato and sweet potato starch dilute and semi‐dilute dispersions were investigated. The results showed that for the two starch dispersions with concentrations ≥c_e, the gelatinisation temperature increased more significantly with increasing concentrations, and storage modulus increased faster than loss modulus with increasing frequency. The potato starch dispersion with concentrations ≥c_e possessed higher entanglement density of the chain segments. The two starch dispersions with concentrations >c_e exhibited shear thinning with increasing frequency. The two starches could only form film at concentrations ≥c_e. So, c_e will be a suitable concentration for regulating the concentration of starch dispersions to obtain the expected physicochemical properties.     

Characteristics of acetylated and enzyme-modified potato and sweet potato flours

The properties of modified potato and sweet potato flours have been determined by incorporating acetyl groups (acetylation) and by treating with glucoamylase (enzymatic modification). Fractionation studies on Sepharose CL-2B showed that the content of high molecular weight fraction decreased, with a proportionate increase in the lower molecular weight carbohydrate fraction, whereas FT-IR indicated changes in crystallinity of the modified starches. The data showed that the degradation of starch is dependent on the type of modification which, in turn, determined its crystallinity and digestibility. The swelling power and solubility patterns of modified flours indicated a greater degree of associative forces in the starch granules. Scanning electron microscopy revealed indentation on acetylated starch granules, and the granules appeared as bunches/clusters, whereas surface erosion was observed in the enzyme-treated samples. The presence of substituent groups in acetylated flour influenced digestibility inversely, whereas improved digestibility was observed in enzyme-modified samples.