富含鱼油和白藜芦醇的凝固型酸奶制备和分析

为了开发富含多种功能因子的营养强化型酸奶,该文将喷雾干燥共包埋的鱼油和白藜芦醇微胶囊粉末应用于凝固型酸奶中,通过对酸奶进行感官评价和测定酸奶的乳酸菌数、pH、持水力、功能因子的稳定性以及油脂氧化情况,探究微胶囊粉末对于酸奶品质的影响。结果表明,微胶囊化包埋有利于掩盖鱼油固有的鱼腥味,可以防止乳清析出,增强凝固型酸奶持水力,改善酸奶质地,并且能够有效提高鱼油氧化稳定性以及二十碳五烯酸、二十二碳六烯酸保留率,对于酸奶乳酸菌数及酸性物质的产生无明显影响。此外,共包埋鱼油和白藜芦醇能够进一步抑制鱼油氧化,提高酸奶营养价值。研究结果将为营养强化型酸奶的开发提供更多理论依据。     

Measurements of Enthalpy Change of Reaction of Formation, Molar Heat Capacity and Constant-Volume Combustion Energy of Solid Complex Yb（Et2dtc）3（phen）

A ternary solid complex Yb(Et2dtc)3(phen) was obtained from the reaction of hydrous ytterbium chloride with sodium diethyldithiocarbamate (NaEt2dtc), and 1, 10-phenanthroline (o-phen·H2O) in absolute ethanol.The bonding characteristics of the complex were characterized by IR.The result shows Yb3 bands with two sulfur atoms in the Na(Et2dtc)3 and two nitrogen atoms in the o-phen.The enthalpy change of liquid-phase reaction of formation of the complex ΔrHθm (l), was determined as being (-24.838±0.114) kJ·mol-1 at 298.15 K, by an RD-496 Ⅲ type heat conduction microcalormeter.The enthalpy change of the solid-phase reaction of formation of the complex ΔrHθm (s), was calculated as being (108.015±0.479) kJ·mol-1 on the basis of an appropriate thermochemistry cycle.The thermodynamics of liquid-phase reaction of formation of the complex was investigated by changing the temperature during the liquid-phase reaction.Fundamental parameters, the activation enthalpy, ΔHθ≠, the activation entropy, ΔSθ≠, the activation free energy, ΔGθ≠, the apparent reaction rate constant k, the apparent activation energy E, the pre-exponential constant A, and the reaction order n, were obtained by a combination of the reaction thermodynamic and kinetic equations with the data from the thermokinetic experiments.At the same time, the molar heat capacity of the complex cm, p, was determined to be (86.34±1.74) J·mol-1·K-1 by the same microcalormeter.The constant-volume combustion energy of the complex, ΔcU, was determined to be (-17954.08±8.11) kJ·mol-1 by an RBC-Ⅱ type rotating-bomb calorimeter at 298.15 K.Its standard enthalpy of combustion, ΔcHθm, and standard enthalpy of formation, ΔfHθm, were calculated to be (-17973.29±8.11) kJ·mol-1 and (-770.36±9.02) kJ·mol-1, respectively.     

维生素E对β-胡萝卜素纳米乳液性质及其饮料稳定性的影响

为提高β-胡萝卜素的水溶性和稳定性,本研究以吐温80、吐温60和磷脂为乳化剂,维生素E为抗氧化剂制备了纳米乳液。测定了纳米乳液的粒径、透光率、色价、储藏稳定性和应用稳定性。结果显示,维生素E对纳米乳液粒径和透光率有轻微影响,对包埋率和色价没有影响。在25、37 ℃和光照下储藏28 d期间纳米乳液的透光率没有发现明显变化,55 ℃储藏期间透光率呈现下降趋势。在25 ℃和光照下储藏28 d期间色价没有发现明显变化,37和55 ℃储藏期间色价有所降低。不同含量的维生素E均提高了β-胡萝卜素的色价保留率。维生素E的加入显著提高了β-胡萝卜素在酸性和中性饮料中的应用稳定性,且添加量为3%时饮料稳定性最佳。     

壳聚糖改性对蒙脱石吸附茶饮料中咖啡碱的影响

通过将壳聚糖负载到蒙脱石表面，制备壳聚糖改性蒙脱石，并利用扫描电子显微镜(scanning electron microscope, SEM)、X射线衍射仪技术(X-ray diffraction, XRD)进行表征，探究改性蒙脱石在脱咖啡碱茶饮料中的应用。结果表明，壳聚糖并未插入蒙脱石层间，而是通过电荷相互作用吸附在蒙脱石表面，形成复合吸附剂。蒙脱石负载壳聚糖的量越多，对咖啡碱的吸附能力越弱，对茶多酚的吸附能力越强。以m(蒙脱石)∶m(壳聚糖)=1∶0.01最佳，此时咖啡碱脱除率约(86.01±1.8)%,茶多酚保留率为(84.52±1.01)%。此外，相较于蒙脱石，负载壳聚糖的蒙脱石能明显抑制铁离子溶出。感官评定显示，壳聚糖改性蒙脱石处理的茶饮料色泽的亮度、香气以及整体滋味更佳。