Thermoplastic starch modified with hydrophobic polyurethane microparticles

Modified thermoplastic starches (TPS) were successfully prepared from corn starch (CS) and hydrophobic polyurethane prepolymers (PUPs) by solid‐state reactions under intensive mixing conditions. The structure and properties were investigated using FTIR, SEM, wide‐angle XRD, tensile testing machine, Brookfield viscometer, and contact angle (CA) meter. The results showed that 98.6 ± 0.4% of PUP was cross‐linked to starch, suggesting a high efficiency of the solid‐state reaction. Compared with unmodified starch, the hydrophobic property of the modified TPS was improved, resulting in an increase of the CAs and a decrease of the Brookfield viscosity. Morphology analysis indicated that the modified starch exhibited increased compatibility between the PUP particle and nature starch, leading to the increased elongation at break.     

Thermoplastic starches modified with polyurethane microparticles: The effects of isocyanate types in polyurethane

In this work, polyurethane prepolymers (PUPs) with different isocyanate types were synthesized and mixed reactively with a starch–water mixture to prepare modified thermoplastic starch (TPS). The effects of the polyurethane isocyanate on the structure and properties of the modified TPS sheets were then investigated. Results from the scanning electron microscope (SEM), FTIR, mechanical tests, and contact angle (CA) confirmed that the modified TPS possessed a homogenous structure, good compatibility between starch and polyurethane (PU), excellent toughness, and hydrophobicity. The degradation experiment also revealed that the PU could be completely separated from the modified TPS. Additionally, almost 100% of the PU particles were cross‐linked to starch matrix, indicating the high efficiency of the modification. The NCO groups with higher reaction activity exhibited a higher number of urethane linkages between the starch matrix and the PU microparticle, resulting in improved compatibility of the two phases of the modified TPS and an increase in toughness.     

聚氨酯预聚体改性氨基硅油柔软剂的制备

利用聚氨酯预聚体(PUP)对氨基硅油进行共混改性制备柔软剂,以改善氨基硅油柔软剂的亲水性。考察了表面活性剂种类、HLB值、乳化温度、pH值、机械搅拌速度、助乳化剂用量等对制得改性氨基硅油乳液稳定性的影响,确定最佳乳化条件为：以AEO-3和AEO-9作为复合乳化剂,HLB值为12,20℃下乳化, pH值为5,搅拌转速为900r/min,助乳化剂正戊醇用量为被乳化物重量的5%。然后将乳化得到聚氨酯预聚体改性氨基硅油（PAS）用于棉织物的柔软整理,通过白度、动摩擦因数、亲水性、手感等测试,考察了其同国内外同类产品应用性能差异,结果发现PAS整理织物相对国产氨基硅油柔软剂亲水性大大提高,柔软性相差不大;其综合性能同进口柔软剂2号相当。     

立式自动压滤机在变性淀粉与糖醇生产中的应用

采用进口立式自动压滤机在湿法变性淀粉生产中替代碟片分离机与卧式刮刀离心机组合，在糖醇生产的结晶工艺中替代离心分离机，取得了良好的效果。本文对两种工艺的分离、洗涤、脱水及节能效果进行了比较。     

芭蕉芋化学成分及其变性淀粉研究进展

芭蕉芋作为一种新型淀粉的来源,具有很大的发展潜力。文章介绍了芭蕉芋的化学成分及其主要成分一淀粉的分子结构、组织结构和物理性质,并综述了采用微波、醚化、乙酰化、接枝等方法改性芭蕉芋淀粉的最新进展。     

Effects of cross-linking and acetylation on oat starch properties

Starch samples separated from oat were modified with two different levels of POCl₃ (0.5 and 1.0 g kg⁻¹) as a cross-linking agent and two different levels of acetic anhydride (6% and 8% (w/w)) for acetylation. Swelling factor, thermal properties and retrogradation measurements were evaluated to characterise the influence of phosphorylation and acetylation on oat starch. Cross-linking decreased the swelling factor and did not improve gelatinization temperature while it increased synaeresis in comparison with native starch. Acetylation increased swelling factor but reduced gelatinization temperature and synaeresis of oat starch.     

Effect of gelatinisation on slowly digestible starch and resistant starch of heat-moisture treated and chemically modified canna starches

The effects of gelatinisation on slowly digestible (SDS) and resistant starch (RS) of native and modified canna starches were investigated. Starch slurries (10% w/w) were gelatinised at 100 °C for 5, 10, 20 and 40 min using a rapid visco analyzer (RVA). Significant change in the degree of gelatinisation (DG) values of all starch samples was observed during the initial 10 min of gelatinisation; after that the DG values increased gradually with gelatinisation time. The RS contents in all gelatinised starches decreased with increasing gelatinisation time, while the SDS values fluctuated. Chemical modification affected DG values as well as RS/SDS contents. The RS contents in 10% (w/w) acetylated, hydroxypropylated, octenyl succinylated and cross-linked canna starches gelatinised at 100 °C for 40 min were 26.6%, 32.0%, 45.3% and 19.8%, respectively, which were higher than that of the native starch (12.4%). Canna starch modified by crosslinking had the highest SDS content when gelatinised for 20-40 min. Modification of canna starch by heat-moisture treatment resulted in a lower content of RS for all treated samples. However, the Vt-HMT25 (canna starch containing moisture content of 25% during heat treatment) when gelatinised for 5-20 min contained a higher amount of SDS, compared to unmodified starch. The most effective modification method for RS and SDS formation was octenyl succinylation, where the sum of RS and SDS approached that of Novelose260.     

Effects of processing conditions and the use of modified starch and monoglyceride on some properties of extruded rice vermicelli

Pasting profile and gel appearance of rice flour, rice flour mixed with the modified starch, MYK-500T and monoglyceride, Monomul 90-35P were examined. The optimum conditions for the extrusion of rice vermicelli obtained were: screw speed 30 rpm; feeder speed, 50 rpm; temperature of three zones, 90 °C:100 °C:100 °C. The rice noodle had white color, good retention of shape but stuck together after cooking. The use of modified starch, and monoglyceride could reduce the stickiness of the product. The noodle extruded from rice flour added with MYK-500T (4 g/100 g blend), and Monomul 90-35P (1 g/100 g blend) was firm and not sticky, showing cooking time at 2 min, cooking weight 315 g/100 g dry noodle, cooking loss 11.1 g/100 g dry noodle and degree of gelatinization 88.9%. The hardness of the product was 1230 g and tensile strength 9.5 g. Sensory evaluation showed that the acceptance of the extruded rice vermicelli was not significantly different from other 3 commercial products prepared by conventional method.     

有机改性蒙脱土对改性淀粉复合膜性能的影响

为了获得高性能的淀粉/蒙脱土纳米复合材料,选取3种改性淀粉为成膜基材,3种有机改性蒙脱土(OMMT)为增强剂,采用溶液流延法制备了复合膜。X-射线衍射说明改性剂和淀粉分子进入蒙脱土片层间发生插层反应。红外光谱结果表明双十八烷基二甲基氯化铵改性蒙脱土(D1821MMT)与氧化酯化淀粉(OAS)、深度氧化淀粉(HOS)具有较强的氢键作用;而十八烷基二甲基苄基氯化铵改性蒙脱土(1827MMT)与羟丙基交联淀粉(HPDSP)存在较强的氢键作用。OAS/D1821MMT复合膜具有较高的抗拉强度(5.80 MPa)和透光率(86.83%);HOS/1827MMT复合膜具有较高的断裂伸长率;HPDSP/1831MMT复合膜水蒸气渗透系数最低(1.30×10-10g·m·m-2·s-1·Pa-1)。研究证实,OMMT与改性淀粉能够形成性能更加优良的纳米复合膜,该膜在食品包装领域具有广泛应用前景。     

壳聚糖改性水性聚氨酯的性能

以聚酯218、聚四氢呋喃醚二醇(PTMEG-2000)和异佛尔酮二异氰酸酯(IPDI)为主要原料,2,2-二羟甲基丁酸(DMBA)为亲水扩链剂,柠檬酸化壳聚糖(CA-CS)为改性剂,合成了壳聚糖改性水性聚氨酯抗菌整理剂(CA-CS-WPU).采用傅里叶变换红外光谱、热重分析、差示扫描量热法对乳液及胶膜的各项性能进行表征...     

Gelatinization and pasting properties of rice starch modified with 2‐octen–1‐ylsuccinic anhydride

Rice starch was modified with various levels of 2‐octen‐1‐ylsuccinic anhydride (OSA). Treatments with OSA at 3, 5, and 10% resulted in starch derivatives with 0.016, 0.033, and 0.070 degrees of substitution (DS( respectively. Thermovisco properties of the derivatives were investigated by differential scanning calorimetry (DSC) and rapid visco analysis (RVA). Water content in the sample was found to have a significant effect on the characteristics of the DSC endotherm. Pasting properties of the OSA‐starch and the effect of pH and salt on the RVA profiles were also studied. In general, with increased OSA‐modification, the starch derivatives swelled and gelatinized at lower temperatures to achieve higher viscosities. Specifically, based on DSC analysis at 80% water, the peak temperature of gelatinization decreased from 68.5 to 63.2°C as the OSA modification increased in DS from 0 (intact starch) to 0.070. On the other hand, RVA results indicate that, for samples undergoing similar increase in OSA modification, the pasting temperature decreased from 88.7 to 51.5°C and the peak viscosity increased from 668 to 6822 cP.     

木薯淀粉与木薯变性淀粉鱼糜加工性质的比较

摘要：本研究比较了木薯淀粉、木薯醋酸酯交联淀粉和木薯磷酸酯交联淀粉对鱼糜加工性质的影响,并测定了二种木薯醋酸酯交联淀粉、二种木薯磷酸酯交联淀粉以及木薯淀粉和鱼糜加工相关的冻融稳定性、透光率、溶解性、膨润度和凝沉性等特性。并将木薯淀粉和四种变性淀粉分别添加到鱼糜中,测定鱼糜冻融过程中的持水性、白度以及凝胶强度等品质特性。结果表明：木薯变性淀粉因引入了磷酸基、羧甲基等亲水性基团,在透光率、冻融稳定性、溶解性和凝沉性等性质方面较木薯淀粉均有提高,添加木薯变性淀粉所得到的鱼糜制品白度、持水性和凝胶强度分别增加了17.7%、10.2%、77.7%。木薯变性淀粉较木薯淀粉更适合用于加工鱼糜。     

聚氨酯改性有机硅在棉织物免烫整理中的作用

介绍了聚氨酯改性有机硅整理剂的合成原理及方法,探讨了整理剂用量、焙烘温度及时间对纯棉织物性能的影响,并通过正交试验确定了最佳工艺条件为:整理剂用量40 g/L,焙烘温度170 ℃,焙烘时间80 s.若与醚化2D树脂混合使用,可使薄型棉织物的DP超过4级,甲醛释放量低.     

Influence of modification method and starch concentration on the stability and physical properties of modified potato starch as wall materials

The object of this study was to investigate the stability of flavor encapsulated in modified starches, and the potentiality of modified starch as wall material. For the flavor encapsulation using freeze-drying technique, native potato starch (NP), β-cyclodextrin (β-CD), maltodextrin (MD) and acid-treated potato starch (ATPS), succinated potato starch (SPS) were used as wall materials and d-limonene was a core material. The properties of wall materials were evaluated by the physicochemical properties such as pasting property, microstructure, moisture absorption ratio and peroxide value of encapsulated d-limonene. The peak viscosity (RVU) of modified potato starch was lower values (299 and 375 RVU) compared to that (579 RVU) of NP. The microstructure of product with SPS showed homogeneous distribution of pore with a regular size in contrast to the irregular arrangement of pore of NP and ATPS, and the microcapsule stabilized by β-CD and MD had smaller pore size than modified starches. Overall the yield of encapsulated products was an increasing trend as the concentration of wall materials was increased from 5 to 10%, and the product with SPS had the highest value (93.35%). The moisture absorption ratio of products with β-CD and SPS did not affected by starch concentration. The peroxide value of encapsulated d-limonene during storage for 16 days had low values below 2.0 meq/kg of oil at all samples except for sample with ATPS. These results indicate that the encapsulated d-limonene with SPS by freeze drying showed the highest flavor retention and the oxidation stability of d-limonene.     

Effect of modified tapioca starch and xanthan gum on low temperature texture stability and dough viscoelasticity of a starch-based food gel

This work investigated the effect of modified tapioca starch and xanthan gum on dough viscoelasticity and texture stability during storage at 4 °C of starch sheets for Chinese shrimp dumplings. Hydroxypropylated starch and hydroxypropylated-crosslinked starch were used to substitute for tapioca starch in the control formulation, and xanthan gum was added to adjust the formulation. During storage, texture of the control became firmer due to amylopectin retrogradation confirmed by differential scanning calorimetry and X-ray diffraction. Conversely, gel sheets containing modified starches showed less texture change. Dough viscoelasticity of the formulations substituted by hydroxypropylated starch were much softer and easier to deform than that of the control one. Dough with hydroxypropylated-crosslinked starch was, however, stiffer and more strain-resistant. Moreover, the formulation comprising the mixture of both types of modified starches and xanthan gum gave dough viscoelasticity similar to that of the control, and provided gel sheet the least texture change. Consequently, this modified formulation could be beneficial for the application of frozen/chilled dumpling wrappers.     

Effects of passive and active modified atmosphere packaging conditions on ready-to-eat table grape

The effects of passive and active modified atmosphere packaging conditions (MAP) on quality of packaged table grape were investigated. To this aim, three films made up of oriented polypropylene and characterized by a different thickness (20, 40 and 80 μm, respectively) were used to package the grape in air (passive MAP) and under three different initial headspace gas compositions (active MAP). As controls, grape samples were also stored without packaging. During a prolonged storage period at refrigerated temperature (5 °C) the headspace gas concentrations, the mass loss, the microbiological stability and the sensory acceptability were monitored. Results obtained highlight that all selected packaging films significantly prevent product decay, thus promoting a substantial shelf life prolongation, if compared to the unpackaged product. In particular, the best results were recorded with the thickest polymeric matrix sealed in air, that assured a shelf life more than 70 days. The active MAPs were not found significant for a shelf life prolongation, due to the fast equilibrium of gas reached in the bags and due to a more pronounced product dehydration.