基于天然大豆油脂体-海藻酸钠的沙拉汁工艺研究

以天然大豆油脂体替代传统沙拉汁中的油脂,并利用多糖海藻酸钠(ALG)作为稳定剂制备新型沙拉汁。结果表明,通过带负电ALG与带正电油脂体的静电相互作用,提高了天然大豆油脂体在弱酸性条件下的分散性和稳定性,0.35%的ALG可在pH4.5下很好地稳定1.0%油脂体乳液。通过体外模拟小肠内油脂消化过程,发现天然大豆油脂体乳液比吐温80-大豆油乳液的游离脂肪酸释放量低10%左右,且ALG进一步延缓了大豆油脂体初期消化速度。高浓度的ALG(0.5%、0.6%、0.8%、1.0%)可分别提高高浓度油脂体乳液(10.0%、20.0%、30.0%、40.0%)的稳定性。以市售沙拉汁为对照,优化了沙拉汁配方中大豆油脂体与ALG的用量,将质量分数为60.0%的大豆油脂体-ALG的乳液(含40.0%油脂体和1.0% ALG)用于沙拉汁配方中,得到粘度与市售配方匹配,稳定性更佳的沙拉汁。新型沙拉汁配方综合了大豆油脂体和海藻酸钠的双重优点,具有含油量低、脂肪消化慢、营养素天然健康,且储存稳定的特点。     

Improvement of Oxidative and Emulsion Stability of Model Salad Dressing by Glucose Oxidase-catalase

ABSTRACT: The oxidative stability of model salad dressing containing 1.0% glucose was determined by measuring the headspace volatile compounds of sample bottles and peroxide values. Glucose oxidase-catalase acted as an anti or pro-oxidant depending on the concentration. As glucose oxidase-catalase increased from 0 to 0.1, 0.2 and 0.3 unit/g salad dressing, the volatile compounds and peroxide values decreased and the enzyme acted as antioxidant (α= 0.05). As glucose oxidase-catalase increased from 0.3 to 0.5 and 0.7 unit/g salad dressing, peroxide values increased (α= 0.05) and the enzyme was prooxidant. The enzyme improved the emulsion stability of the dressing at 0.5 and 0.7 unit/g sample (α= 0.05).     

番茄汁液流变性质的关联

对经45、32、24和16目筛网过筛所得番茄汁液的流变性质进行了研究。采用旋转式粘度计测定了番茄汁的剪切速率-剪应力数据。通过剪切速率-剪应力实验数据的关联发现,番茄汁液的流变行为可用Bingham模型表征。确定了不同温度和不同网目下番茄汁液的稠度指数和屈服应力。同时也建立了不同网目下番茄汁液的表观粘度与温度函数关系的关联式。     

Detection of Mustard, Egg, Milk, and Gluten in Salad Dressing Using Enzyme-Linked Immunosorbent Assays (ELISAs)

ABSTRACT:  Enzyme-linked immunosorbent assay (ELISA) is a commonly used method for the detection of trace amounts of potentially allergenic protein residues in foods. However, food matrices and processing conditions can affect the detection of protein residues. The effects of acidity on the detectability of several allergenic proteins commonly found in salad dressing using ELISAs was investigated. First, recovery experiments were performed on salad dressing formulated with 0 to 1000 ppm mustard flour (mustard). The mean percent recovery for mustard from the salad dressing was only 7.7%± 1.6%. When the pH of the salad dressing was adjusted to pH 7 prior to spiking with mustard, recovery improved to 94.1%± 7.6%. However, if the pH was adjusted to pH 7 after spiking and extraction, the recovery was only 11.1%± 1.7%. When vinegar was spiked with mustard flour at pH 3, 3.5, and 4, detectability of mustard was lowest at pH 3. Basic extraction of mustard proteins from salad dressing did not improve the mustard detection. Acidic salad dressing matrices reduced the detectability of mustard by the mustard ELISA probably because of acid precipitation of mustard proteins that renders them insoluble and nonextractable. Commercial salad dressings containing 100 ppm (mg/kg) of egg, milk, or gluten were analyzed every 2 to 4 d for 90 d using 3 commercially available ELISAs. A decrease in the detection of the egg, milk, and gluten in the salad dressing upon storage was observed. Our study highlighted the importance of evaluating the utility of various ELISAs for specific food matrices and the recovery as a function of product storage.     

Rheological Characterization of Low-calorie Milk-based Salad Dressings

Oil-in-water emulsions of different quantitative composition, containing milk powder and locust bean gum. as stabilizing agents, showed similar rheological behavior: time-dependent thixotropic character and yield stress. Thixograms obtained for each sample could be modelled through the Hahn equation for the different shear rates. The analysis of the Hahn parameter variation for each sample as a function of shear rate led to a function σ= f(γ, t). Predicted shear stress values had relative errors lower than 10% in 99.9% of the samples studied. Analysis of composition influence on the rheological parameters showed an interactive role of gum, milk and acetic acid concentrations on emulsion consistency.     

番茄浆料的流变特性

对不同浓度的番茄浆料在30～60℃时的流变学性质进行了研究.结果显示,番茄浆料为假塑体系,屈服应力值的范围比较宽(40～140Pa).通过回归分析得到数学模型K=K0exp(Ea/RT)和K=Aexp(BC).可以分别用来描述温度和浓度对番茄浆料稠度系数的影响.利用这些方程,可以预测实际加工过程中不同温度和不同浓度条件下番茄浆料的粘度.     

车前子胶的流变特性研究

本实验通过浓度、剪切力、温度、pH、盐度、水化时间、冻融等变化对车前子胶溶液表观黏度的影响,对车前子胶溶液的流变性进行了研究。结果表明:车前子胶溶液为"非牛顿流体",具有"假塑性"。其表观黏度随质量分数的增加逐渐增加;体系温度升高可导致溶液黏度降低,溶液在pH5～11时较稳定;车前子胶对NaCl具有良好的兼容性,Ca2+对车前子胶溶液有显著的增稠效应,其增稠效果与离子浓度呈正相关。此外,车前子胶溶液有良好的抗降解性能,冻融变化使车前子胶溶液黏度有所升高。     

Ultrasonic Spectroscopy Study of Salad Dressings

Ultrasonic velocity and attenuation spectra (1 to 100 MHz) of salad dressings with different disperse phase volume fractions (φ= 0 to 0.394) and mean droplet radii (0.3 to 0.6 μm) were measured at 25 °C. There were significant differences between the experimental measurements and theoretical predictions due to droplet flocculation. The measured attenuation coefficient was lower than expected at low frequencies because of thermal overlap effects, but it was greater than expected at high frequencies because of scattering. These deviations could be accounted for using an effective medium theory. Results suggest that ultrasonic velocities at 14 MHz were independent of droplet size and could be used to measure droplet concentration of salad dressings.     

电子束辐照对沙拉酱微生物及品质的影响（网络首发、推荐阅读）

对市购沙拉酱用0、1、2 kGy不同剂量进行电子束辐照,研究电子束辐照对沙拉酱的杀菌效果及辐照后常温放置40 d后产品的微生物、色泽、质构、风味、稳定性等指标的变化,为沙拉酱物理冷杀菌的技术可行性和工艺设定提供技术参考依据。结果表明,电子束辐照对外源添加致病菌鼠伤寒沙门氏菌、大肠埃希氏菌、金黄色葡萄球菌及沙拉酱自身菌落总数、霉菌和酵母有良好的杀灭效果,1 kGy电子束辐照可降低致病菌3~6个log,菌落总数、霉菌和酵母不再检出。室温放置40 d后,感官评价发现1 kGy电子束辐照对沙拉酱色泽、体态、香气、滋味无显著影响,电子鼻分析、质构参数及离心解析率也与未辐照处理无明显差别,但2 kGy电子束辐照的滋味评分显著低于未辐照处理和1 kGy辐照处理,质构参数与未辐照处理、1 kGy辐照处理差异显著。电子束辐照可有效控制沙拉酱中致病菌,1 kGy剂量处理对沙拉酱色泽、质构、风味、稳定性无明显影响,可用于沙拉酱杀菌保鲜。     

荸荠淀粉糊流变性质的研究

为有效开发利用荸荠淀粉,研究不同浓度的淀粉、食盐、蔗糖、黄原胶、卡拉胶以及瓜尔豆胶对荸荠淀粉糊动态及静态流变特性的影响,结果表明:荸荠淀粉糊是典型的剪切稀化的非牛顿型流体,荸荠淀粉浓度的改变以及食盐、蔗糖、黄原胶、卡拉胶和瓜尔豆胶的添加都对此性质不产生影响。表观黏度与剪切速率呈负相关。淀粉浓度越高,体系的储存模量(G′)、损耗模量(G″)越大,但损耗角正切值(tanδ)越小;食盐可提高体系的G′、G″和tanδ;高浓度的蔗糖使体系的G′、G″增大,但蔗糖的加入却使体系的tanδ降低;高浓度的黄原胶、卡拉胶和瓜尔豆胶3种亲水性胶体可提高体系的G′、G″和tanδ。     

沙蒿籽胶的流变学性质研究

研究了沙蒿籽胶的静态流变学特性和动态流变学特性。静态流变学表明:沙蒿籽胶溶液是触变性流体,其表观粘度随质量分数的增加而增加,且随剪切速率变化的影响符合Herschel-Bulkey模型;温度、pH值等对沙蒿籽胶溶液的表观粘度影响较小;盐的加入能改变沙蒿籽胶溶液的粘度。动态流变学特性表明:沙蒿籽胶溶液显示弱凝胶特性。     

造纸污泥的流变特性测试

以造纸污泥为研究对象,采用NXS-11型旋转黏度计在室温(23·5℃)条件下对质量浓度为55%、60%和65%的污泥进行剪切应力测试,获得不同剪切速率下对应的剪切应力和黏度值,得出造纸污泥的流变曲线,并回归出流变方程和黏度表达式。可以看出浓度为55%和65%污泥的流体类型为假塑性流体,60%污泥的流体类型为宾汉流体。     

辛烯基琥珀酸淀粉酯的流变性质(Ⅰ)

通过合成不同取代度的辛烯基琥珀酸淀粉酯,采用旋转粘度计研究了不同产品淀粉糊的流变特性.结果表明,所有淀粉样品糊均呈现假塑性流体特征.取代度越大的样品,其糊的表观粘度越高,触变性相应减弱.     

果仁糖果用高质量分数糖浆的流变特性

采用R/S plus流变仪对不同质量分数（80%～92%）的果仁糖果用蔗糖-麦芽糖混合糖浆在不同温度下的流变特性进行研究。结果表明：温度对黏度的影响可用阿累尼乌斯（Arrhenius）方程表示,质量分数对黏度的影响可用幂函数的形式表示。通过回归分析,给出在研究的温度和质量分数范围内黏度随温度、质量分数各自变化的函数式以及温度和质量分数对黏度的综合方程式。所建立的方程式能够成功地描述在相应质量分数和温度范围内的数据。     

小麦淀粉-离子液体溶液流变性质的研究

采用哈克流变仪研究小麦淀粉-离子液体氯化1-烯丙基-3-甲基咪唑([AMIM]Cl)溶液的流变性质。结果表明：不同质量浓度的小麦淀粉-离子液体[AMIM]Cl溶液均为假塑性流体;离子液体溶液表现出黏度随剪切速率的升高而降低,溶液体系随着淀粉质量浓度增高而剪切稀化增强;溶液的触变性随温度的升高而减小。     

Rheological modeling of tubular weft knitted textiles

Tubular-knitted fabrics are used in various medical and tissue engineering applications. The mechanical behavior of such structures is important and therefore, it should be considered to design the artificial grafts and prosthesis prior to specific applications. Twenty different structures of tubular silk weft-knitted fabrics (five knitting patterns, two different yarn counts, and two different stitch lengths) were produced, and their mechanical properties were measured in longitudinal and circumferential directions under the constant rate of elongation. Twelve samples were used to study the performance of seven rheological models in order to investigate the mechanical performance of tubular-knitted structures. The results showed that the rheological model of a non-linear spring (that followed the power rule) parallel with a Newtonian dashpot could properly estimate the stress–strain curves of the tubular fabrics under loading. Mathematical equations of this model were derived based on the rheological parameters of the structural elements of the weft-knitted fabrics. The model validation was also investigated using the eight different remaining tubular structures. The results showed that the developed model could be used to describe the mechanical behavior of the knitted structures based on the viscoelastic coefficients of the knitted fabrics.     

SPI/甘油水溶液流变性的研究

采用流变仪初步研究了甘油对大豆分离蛋白（SPI）静态流变性能的影响及其溶液性质,讨论了添加甘油后,SPI水溶液剪切粘度随浓度和温度的变化,并与没添加甘油的SPI水溶液对比。结果表明：SPI/甘油水溶液体系呈现剪切变稀性,甘油不仅降低了体系的粘度和减弱其剪切变稀性,同时还提高了体系的抗热性能。     

4种蛋黄酱的流变特性比较研究

针对4种蛋黄酱样品(丘比蛋黄酱、丘比蛋黄酱(2005)、丘比香甜味蛋黄酱、丘比千岛酱),对其进行成分、流变特性(静态流变特性和动态流变特性)及感官评定实验。静态流变测定表明：蛋黄酱样品呈现出触变性、假塑性;动态流变测定表明：蛋黄酱样品显示弱凝胶特性。结果表明：丘比蛋黄酱的流变学特性、感官特性最优,丘比蛋黄酱(2005)其次,丘比香甜味蛋黄酱再次,丘比千岛酱最差。     

大豆磷脂流变性能的研究

分析了影响流化磷脂流变特性的因素。结果表明:在一定的实验条件下,流化磷脂的粘度随着剪切速率的增加而减小,其变化符合幂律方程。流化磷脂的粘度与磷脂的质量百分数、温度及无机盐的质量百分数有关;随着磷脂的质量百分数增加,流化磷脂的粘度也随着增加;随着无机盐的质量百分数增加及温度升高,流化磷脂的粘度下降。