魔芋胶和玉米淀粉混合物黏弹特性的研究

目的 研究魔芋胶对玉米淀粉黏弹特性的影响。方法 以玉米淀粉为原料, 加入不同比例的魔芋胶, 采用动态流变仪来研究魔芋胶玉米淀粉糊化混合物的黏弹特性。结果 Power-Low模型能够有效地表征魔芋胶玉米淀粉糊化混合物的流变性能。魔芋胶玉米淀粉糊化混合物为假塑性流体, 与单独的玉米淀粉糊相比, 随着魔芋胶的添加量增大, 糊化混合物黏稠性增大, 假塑性增强。随着频率的增大, G?和G?均增大, 损失正切值tan δ＜1, 说明魔芋胶的加入使得糊化混合物具有优越的黏弹性。结论 当魔芋胶/玉米淀粉质量比为0.4:0.8时, 糊化混合物弹性最小, 黏性最大, 糊化混合具有更好的协同增稠作用, 即糊化混合物流体流动特征显著。     

黑麦非淀粉多糖凝胶形成及质构特性的研究

本文研究了黑麦非淀粉多糖（NSP）凝胶形成条件及质构特性。比较了水溶液、碱溶液、乙醇-酶-水溶液提取得到的NSP凝胶形成条件,用质构仪测定不同质量分数、pH值、添加蔗糖和Ca^2＋时NSP凝胶的质构特性。结果表明,冷藏4℃时,NSP成胶效果好;水提和乙醇-酶-水提NSP凝胶形成时间大致相同,碱提NSP凝胶形成时间相对较短;3种提取方法所形成的凝胶的硬度、强度和黏度各指标随着质量分数的增大而增大,以水提较优;在中性条件下,水提6％NSP具有较好的质构特性,添加适量的蔗糖能够改善凝胶的性能,而Ca^2＋的添加会使凝胶性能明显下降。     

不同工艺茶叶非淀粉多糖的理化特性研究

目的:探讨不同处理工艺对茶叶不溶性非淀粉多糖(INSP)营养成分及理化性质的影响。方法:采用水及碱液分别制备不同种类非淀粉多糖,通过营养成分、水合能力(包括吸水力、持水性、膨胀率)、吸附性能(包括持油性、胆酸盐、亚硝酸根离子吸附能力)的测定,分析处理工艺对茶叶INSP的影响。结果:2种工艺制备的INSP间营养成分存在一定差异,尤其是影响其理化性质的氨基糖与碳水化合物,其中碱法制备的INSP中氨基糖与碳水化合物含量分别是水法制备的1.60倍与1.35倍;处理工艺对茶叶INSP的理化性质亦产生较大影响,适度碱处理获得的INSP的水合能力与吸附性均优于水处理,其中膨胀率、持水力与结合水力分别为水处理的1.22、1.11、1.20倍。结论:不同处理工艺对茶叶INSP的营养成分及理化性质均产生较大影响,实验结果为茶叶非淀粉多糖的开发利用提供了参考数据。     

酶法液化玉米淀粉制备麦芽糊精的研究

本文利用中温型和耐高温型α－淀粉酶水解玉米淀粉生产麦芽糊精。研究了ＤＥ值、液化得率以及产品透明度与反应时间、反应温度之间的关系。结果表明用玉米淀粉酶法制备麦芽糊精的最佳条件应为高温短时反应。     

谷物非淀粉多糖特性、制备及分析方法研究进展

该文综述了国内外有关谷物非淀粉多糖(戊聚糖和β-葡聚糖)的特性、制备及分析鉴定方法的研究进展,以期为谷物非淀粉多糖在食品工业中的应用及进一步的深入研究提供参考。相关研究表明,谷物非淀粉多糖是由一系列理化性质和生理功能不同的组分组成,具有降血脂、降低胆固醇、预防心血管疾病和增强免疫力等生理功效,在功能性产品等领域具有较好的应用前景。目前对谷物非淀粉多糖的研究还存在一定的不足:谷物非淀粉多糖的分离纯化非常复杂,均一组分多糖的获得存在一定难度;谷物非淀粉多糖不同组分的分子结构和功能特性有待进一步深入研究;谷物非淀粉多糖功能性产品的开发需要加大力度。     

瓜尔豆胶对锥栗淀粉糊化和流变学特性的影响

以新鲜锥栗为原料,考察了瓜尔豆胶对锥栗淀粉的糊化特性和流变学特性的影响。结果表明,向锥栗淀粉中添加瓜尔豆胶后,锥栗淀粉糊化溶液的峰值黏度和终值黏度增大,且随瓜尔豆胶添加比例的增加而增大;添加瓜尔豆胶增大了锥栗淀粉的起始糊化温度和峰值糊化温度,提高了锥栗淀粉的吸热焓,使得糊化过程更长,吸热更多。添加瓜尔豆胶后的锥栗淀粉溶液显示为假塑性流体,剪切变稀现象更为明显,具有更大的黏弹性。添加瓜尔豆胶后,混合物形成的凝胶表面空隙中填充物增多,空隙数量减少,且空隙分布更加均匀。     

香豆胶与玉米淀粉混合物流变特性的研究

为了研究不同质量分数（0%、2%、4%、6%、8%）的香豆胶对玉米淀粉糊化混合物剪切流变特性与动态黏弹性的影响,使用旋转流变仪,采用Herschel-Bulkley模型对剪切流变数据进行分析。测试结果为：香豆胶与玉米淀粉糊化混合物是假塑性流体。随着香豆胶质量分数的增加,混合物稠度系数K显著增加,下行线流体指数n显著降低,假塑性增强。动态黏弹性测定结果为：混合物贮能模量（G''）和损耗模量（G''）都随香豆胶质量分数增大而增大,损耗角正切tanδ＜1,说明香豆胶的添加增大了混合物的黏弹性。当香豆胶质量分数为8%时,混合物黏性最大,弹性最小,混合物具有更好的黏弹性。     

麦芽糊精替代脂肪对冰淇淋浆料流变学特性的影响

为了研究麦芽糊精替代脂肪对冰淇淋浆料流变学特性的影响,研究了麦芽糊精替代0%、25%、50%、75%脂肪的冰淇淋浆料的流动性、稠度和分子网络结构破坏、恢复等情况。结果表明,各替代率的浆料均属于假塑性流体,具有触变性,随脂肪替代率增大,浆料假塑性增强,稠度降低,流动性增大,屈服应力减小,浆料结构更容易被破坏。替代增强了浆料剪切结构恢复能力和热稳定性。0%、25%替代率浆料的G’、G″均明显大于50%、75%替代率,25%脂肪替代几乎不影响浆料G’,此外,替代增强了浆料G″对频率的依赖性,随频率增大显著上升。      

坛紫菜多糖对3种晶型淀粉流变特性的影响

目的 研究坛紫菜多糖(Porphyra haitanensis polysaccharides, PHP)对玉米淀粉(corn starch, CS)、马铃薯淀粉(potato starch, PS)和莲子淀粉(lotus seed starch, LS)流变特性的影响。方法 通过流变仪测定不同浓度PHP对CS、PS和LS流变特性的影响。结果 PHP的加入提高了CS、PS和LS的剪切应力,使得CS和LS的恢复力增强但PS减弱,同时能显著降低CS滞后面积而显著增大LS的滞后面积,但只有添加0.8%和1.2%PHP才能显著降低PS的滞后面积;振幅扫描结果表明PHP的加入提高了CS和LS的储能模量(storage modulus, G’)和损失模量(loss modulus, G”),而只有0.4%和0.8%PHP的加入降低了PS的G’和G”;频率扫描结果表明PHP使PS和LS的G’和G”明显增大,而0.8%和1.2%PHP使CS的G’和G”降低;温度扫描结果表明PHP的加入使得CS和PS的G’增大,而使LS的G’降低。结论 PHP的加入提高了CS、PS和LS的抗剪切稀化作用,增强了CS和L...     

大米淀粉为基质制备低DE值麦芽糊精的研究

研究了以大米淀粉为原料制备脂肪模拟物的工艺条件,通过单因素试验研究了酶添加量、反应时间、反应温度和底物浓度对产品DE值的影响,并在此基础上通过正交试验确定了制备工艺的最佳条件:酶添加量2ml,水解时间15min,水解温度92℃,该条件下制备的水解物DE值2.72。利用这种糊精替代奶糖中的油脂,其结构特性可达到或接近对照产品的品质。     

The effect of pectin concentration on viscoelastic and sensory properties of processed cheese

The effect of pectin addition on viscoelastic properties of model processed cheeses with 40% w/w dry matter and 50% w/w fat in dry matter after 42 days of storage at temperature 6 ± 2 °C has been investigated using dynamic oscillation rheometry (plate–plate geometry; frequency range 0.1–50.0 Hz; temperature 20 °C). The role of pectin concentration (0.2%, 0.4%, 0.6% and 0.8% w/w) has been studied. Also, the sensory evaluation of samples has been made to assess cheese appearance, rigidity, spreadability and flavour. All samples with the pectin addition were more rigid and less spreadable compared with processed cheeses without pectin. With the increasing concentration of pectin the storage ( G ') and loss ( G ") moduli rose at the whole tested frequency range (0.1–50.0 Hz). Growing pectin content resulted in the decrease in loss tangent (the nature of gel was changed to more elastic material). The dependence of processed cheese rigidity on pectin concentration (in range 0–0.8% w/w) was not linear. The appearance and flavour were not worse by pectin addition.     

Rheological properties and gel characteristics of polysaccharides from fruit-bodies of Sparassis crispa

Rheological properties and gel characteristics of Sparassis crispa polysaccharides (SCPs) were investigated under various concentrations, temperature, pH, salt concentrations, and sucrose concentrations. SCP solutions behaved as shear thinning pseudoplastic fluids; apparent viscosity increased with concentrations but decreased with extreme conditions and was highest for 1% SCPs at 80 ℃ under neutral conditions; 5% SCPs solutions formed a hysteresis loop and exhibited thixotropic properties. By oscillatory measurements, SCPs were viscoelastic materials. 0.5% and 1% SCPs solutions exhibited viscous behavior at low frequency and enhanced elastic property with the oscillation frequency increased. With the concentration increased to 3% and 5%, the elastic property was predominant in solutions and exhibited gel-like behavior. SCPs gel textural properties and water holding capacity increased with concentration (to 20%) and decreased with salinity, extreme sucrose, and pH. 10% SCPs gels were optimized at 10% sucrose in neutral conditions. Thus, these results implied SCPs had the potential utilization as a new hydrocolloid source in food industries.     

Effect of heating temperature,pH, concentration and starch/whey protein ratio on the viscoelastic properties of corn starch/whey protein mixed gels

The viscoelastic properties of corn starch (CS) gels were more dependent on heating temperature, while the properties of whey protein isolate (WPI) gels were more dependent on pH. Thus heating temperature (75, 85, 95 °C) and pH (5, 7, 9) were varied to obtain a series of mixed gels with interesting viscoelastic properties. WPI gels showed extensive stress relaxation (SR) indicative of a highly transient network structure, while CS gels relaxed very little in 2000 s. Based on SR results, it appeared that CS/WPI mixed gels with 25 and 50% CS formed compatible network structures at 15% total solids only at pH 9. This supposition was supported by SEM microstructures obtained for dehydrated gels and a synergistic increase in the large‐strain fracture stress for these gels. Some synergy was also found for mixed gels at 30% total solids at pH 9, while at pH 7 the mixed gels seemed to contain separate additive WPI and CS networks unlike the case for pH 7 at 15% total solids. In both cases (15 and 30% total solids) the degree of elasticity of the mixed gels decreased as the WPI content increased. Mixed gels (CS:WPI = 0.5) at pH 9 showed increased fracture stress and fracture strain relative to the same gels at pH 7. This suggests that a unique chemical compatibility exists at pH 9 and results in gels that combine the elasticity of CS and the internal stress dissipation of WPI. © 2001 Society of Chemical Industry     

Comparative studies of the degradation of non-starchy polysaccharides by sorghums and barleys during malting

The β-D-glucan of whole grains of four sorghum (Sorghum bicolor (L) Moench) varieties grown in Nigeria, unlike those of barley, is not significantly reduced during malting. Pentosan level, while enhanced in barley (Hordeum rulgare L) during the same period, dropped in sorghum. Apparently sorghums have very low β-D-glucan degrading endo β 1–3,1-4 glucanase activity as observed from their failure to hydrolyse their isolated endosperm cell walls and barley β-D-glucan extracted in water at 40°C.     

Viscoelastic properties of reconstituted cassava dough

The influence of water (60–70%) and salt (1–2%) content on the viscoelastic properties of cassava dough, reconstituted from cooked flour, was studied using a controlled strain rheometer. Reconstituted cassava dough behaved as a solid-like material with the storage modulus (G') predominant over the loss modulus (G"). As the water content was increased, G' decreased and G" increased; but tan δ was practically independent of the water content. This behaviour suggested that water had plasticising effects, but probably did not change dough structure. The effect of salt content on the dynamic rheological properties of cassava dough was not significant, except for G" values at water contents close to 60%.     

金钱菇多糖的流变学性质研究

从金钱菇子实体水提残渣中纯化获得了一个多糖组分JQPs,采用DHR-3型旋转流变仪研究了JQPs溶液流变学性质,为其在食品工业中的应用提供理论支持。静态流变学实验结果表明,JQPs溶液流动指数n<1,为假塑性流体,浓度越高其假塑性越明显。通过对溶液流动曲线的拟合,发现幂律方程可以作为描述JQPs溶液流动曲线的模型;动态粘弹性实验表明JQPs溶液的G’和G″在1¹00rad/s扫描频率下与测试浓度和测试温度均具有一定的相关性。一定温度下,随着浓度的增加,G’的增加速率超过G″,当浓度达到2.0%时曲线重合,开始形成弱凝胶。浓度为2.5%的JQPs溶液的G’和G″随着温度的升高而逐渐减小,在15℃时基本重合,开始形成弱凝胶。      

Effects of exopolysaccharide-producing cultures on the viscoelastic properties of reduced-fat Cheddar cheese

The objective was to study the influence of different exopolysaccharide (EPS)-producing and nonproducing lactic cultures on the viscoelastic properties of reduced-fat Cheddar cheese. Changes in the viscoelastic properties were followed over a ripening period of 6 mo. Results showed that the elastic, viscous, and complex moduli were higher in reduced-fat cheeses made with EPS-nonproducing cultures than in full-fat cheese. No differences in the viscoelastic properties were found between young reduced-fat cheese made with a ropy strain of Lactococcus lactis ssp. cremoris (JFR1) and its full-fat counterpart. Interestingly, the changes in viscoelastic moduli in both full-fat cheese and reduced-fat cheese made with JFR1 during ripening followed the same pattern. Whereas the moduli increased during the first month of ripening in those 2 cheeses, a dramatic decrease was observed in all other cheeses. Slopes of the viscoelastic moduli as a function of frequency were lower in the full-fat than in reduced-fat cheeses. The creep test showed that fresh reduced-fat cheese made with JFR1 was less rigid and more deformable than that made with EPS-nonproducing cultures. The creep and recovery properties of young reduced-fat cheese made with JFR1 and the full-fat type were similar. No differences were found in the viscoelastic properties between reduced-fat cheese made with no EPS and those made with EPS-producing adjunct cultures of Streptococcus thermophilus. After 6 mo of ripening, cheeses made with EPS-producing cultures maintained lower elastic and viscous moduli than did those made with no EPS.     

提高多糖类可食性膜机械性能的研究进展

多糖类可食性膜的机械强度强于蛋白类可食性膜,但是还不足以应用到食品包装中。影响多糖类可食性膜机械性能的主要因素有成膜原料中各组分性质、制膜工艺以及贮藏条件等。可通过添加增塑剂、交联剂和改进成膜工艺,来提高多糖类可食性膜的机械性能。     

Influence of gluten on the viscoelastic properties of starch pastes and gels

Viscoelastic properties of dispersions (60–300 g kg⁻¹) of gluten (G) and wheat starch (S) blends (0 < G/S < 0·20) and wheat flour have been studied during heating and cooling. In both cases, the moduli followed power law relationships with concentration. The temperature at which the transient network development began, caused by granule–granule interactions, decreased as the concentration increased and increased with an increase in the proportion of gluten. Moreover, gluten weakened the strength of both starch pastes and gels, as shown by the lower values of the moduli. The viscoelastic behaviour of flour samples reflected the role played by internal lipids. A structural model is proposed in order to explain the influence of gluten on the rheological behaviour of starch pastes and gels. © 1998 Society of Chemical Industry.