单硬脂酸甘油酯对棕榈硬脂固体脂肪含量及硬度的影响

食品工业中通常利用乳化剂调控塑型脂肪的物理性质及加工性能,其中,单硬脂酸甘油酯(GMS)是应用较为广泛的乳化剂。通过考察质量分数1%,2%,4%的GMS对棕榈硬脂在不同温度下的固体脂肪含量(SFC)、硬度及微观结构的影响,发现:棕榈硬脂及其与质量分数1%,2%,4%的GMS混合物的SFC和硬度随着温度的升高而降低。GMS的添加量对棕榈硬脂SFC的影响在较高温度(21.1~33.3℃)下更显著,当GMS添加量高于1%时,棕榈硬脂的SFC随GMS质量分数的增加而增加。而在15~30℃时,4%GMS的棕榈硬脂的硬度显著高于其它质量分数,且结晶颗粒细小,结晶网络结构致密。结果表明,在温度高于30℃时,添加GMS可以增加棕榈硬脂的SFC及硬度,且减小其结晶颗粒粒度,赋予更为致密的结构,这对棕榈硬脂基塑性脂肪在温度较高季节的储运及品质改善提供了理论依据。     

大米淀粉-甘油单棕榈酸酯复合物的制备及其老化性质研究

目的 为了减缓大米淀粉在加工过程中的老化,延长大米淀粉制品的货架期,制备具有抗老化效果的大米淀粉-甘油单棕榈酸酯复合物。方法 以复合指数为评价指标,通过单因素及响应面试验对复合物制备工艺中甘油单棕榈酸酯添加量、复合温度和复合时间进行优化,对大米淀粉及最优条件下制备的大米淀粉-甘油单棕榈酸酯复合物的溶解度、膨胀度、冻融稳定性和糊化特性进行了测定。结果 试验得到的最佳制备工艺参数为：甘油单棕榈酸酯添加量5%、复合温度80 ℃、复合时间30 min。同时与大米淀粉相比,大米淀粉-甘油单棕榈酸酯复合物的溶解度、膨胀度、冻融稳定性、糊化特征参数均呈下降趋势,其中冻融后复合物的析水率下降了35.62%。 X衍射结果表明,复合物的晶型由A型向V型转变。结论 大米淀粉-甘油单棕榈酸酯复合在一定程度上可延缓淀粉老化。     

抗坏血酸棕榈酸酯对玉米油储藏稳定性的影响

采用Rancimat法测定不同抗坏血酸棕榈酸酯（AP）添加量下玉米油的氧化诱导时间,筛选出与添加50 mg/kg特丁基对苯二酚(TBHQ)玉米油氧化诱导时间相近的150 mg/kg AP添加量作为玉米油中AP目标添加量,开展6周玉米油储藏加速试验,每7 d取样检测酸值、过氧化值、回色（红值）、植物甾醇含量和维生素E含量,同时与TBHQ组（添加量50 mg/kg）、充氮组及空白组样品进行比较,分析AP对玉米油储藏稳定性的影响。结果表明：在玉米油储藏过程中,AP组样品与TBHQ组、充氮组样品在酸值、过氧化值、回色（红值）及植物甾醇含量方面无明显差别;但添加AP对玉米油中维生素E的保留作用明显优于添加TBHQ及充氮。     

抗坏血酸棕榈酸酯对油脂的抗氧化效果观察

抗坏血酸棕榈酸酯国外已用作食品抗氧化剂，１９７７年世界粮农组织已批准作为强化剂和食品抗氧化剂，本研究试用本实验室合成的抗坏血酸棕酸酯，进行了对食用同的抗氧化效果观察，结果说明合成的抗坏血酸棕榈酸酯具有明显的防止油脂氧化的作用，效果优于ＢＨＡ和茶多酚。     

母乳中二位棕榈酸酯含量分析及研究现状

综述了中国及欧美等国家母乳、动物乳中sn-2棕榈酸酯含量对比,以及对婴幼儿生理功能的研究报道,并对sn-2棕榈酸酯在婴幼儿食品中的应用和潜在前景进行了展望。     

抗坏血酸棕榈酸酯测定方法的比较

将改进滴定碘法应用于抗坏血酸棕榈酸酯含量的测定,并与碘滴定法和硅钼兰分光光度法进行了比较。结果表明,几种常用方法的测定结果略有差异,《食品添加剂手册》中的碘滴定法由于溶液混浊影响终点判断,导致结果偏高,重现性较差;硅钼兰分光光度法灵敏度较高,但需要试剂多,测定周期长;滴定碘法与GB 16314-1996中方法的测定结果在5%水平上无显著差异,但由于滴定碘法中淀粉指示剂变色更明显,易于判断滴定终点,方法的精密度更高,且简单快速,可用于抗坏血酸棕榈酸酯含量的日常检测。     

Vc棕榈酸酯的合成工艺改进

在V_C棕榈酸酯的合成过程中,将反应温度从20℃提高到 24℃,W(硫酸)=99％的溶液改为100％,在产品收率基本 不变的情况下反应时间由48h降到了36h。在精制过程 中,用已烷代替正己烷,用氯仿替代已醚,成本降低,溶剂 回收率提高5%。      

酶促反应合成蔗糖棕榈酸酯的研究

讨论了以Novozym 435脂肪酶为催化剂,以蔗糖和棕榈酸为底物的糖酯合成反应及其影响因素.考察了在丙二醇和正己烷存在下,底物酸糖摩尔比、含水量、温度、脂肪酶浓度、时间以及摇床速度对转化率的影响.实验结果表明,底物棕榈酸与蔗糖的摩尔比为1.2∶1.0、含水量为4%,反应温度为65℃、脂肪酶浓度为棕榈酸质量的4%、反应时间为4.5 h、摇床速度为200 r/min时,棕榈酸的转化率可达到86.94%.     

L-抗坏血酸棕榈酸酯的抗氧化效果研究

L-抗坏血酸棕榈酸酯(AP)是具有功能性、营养性、无毒、高效的抗氧化剂,应用范围广泛。本实验以乌桕脂棕榈酸甲酯为原料,采用化学法将其与抗坏血酸合成AP,并将其应用到大豆油与菜籽油当中,与BHA、TBHQ、VE及AP/VE效果相比较,评价其抗氧化效率。结果表明,AP具有显著的抗氧化性,是一种安全、高效的抗氧化剂和增效剂。     

基于山梨醇酐单棕榈酸酯防雾膜制备与性能研究

为研究山梨醇酐单棕榈酸酯的防雾效果,以山梨醇酐单棕榈酸酯为主要防雾材料,通过造粒得到防雾母料,三层吹塑共挤得到防雾聚烯烃薄膜,并对防雾母料造粒加工性能、薄膜防雾性能、光学性能、力学性能进行测试。结果表明,随着防雾剂在母料中含量的增加,母料熔点降低,融熔指数提高,流动性得到提升,利于母料的加工;当防雾剂在薄膜中含量为时,水滴在薄膜表面接触角为9.72°,薄膜的防雾等级在水浴热雾与急速热雾法测试条件下可到达1级;防雾剂含量在薄膜中含量为1.5%高温测试环境下的持久性达到168 h;随着防雾剂含量继续增加,薄膜的力学性能与光学性能均不同程度的下降,防雾剂在薄膜中的含量在达到防雾要求时应控制在适当水平。     

The Effect of Minor Components on Milk Fat Microstructure and Mechanical Properties

ABSTRACT: Although minor polar components affected the kinetics of milk fat crystallization, its structure and mechanical properties remained unchanged. At 5 °C, a granular microstructure was observed, while at 20 °C, a combination of granular and spherulitic microstructures were observed. By 27.5 °C, only spherulites were present after 24 h. There were no differences observed in the fractal dimension (D) determined by microscopy or rheology for anhydrous milk fat, milk fat triacylglycerols and MF‐TAGs with added diacylglycerols at 5 °C. There was, however, a strong temperature effect on D, increasing from 1.87 at 5 °C to 1.98 at 22.5 °C. The yield force and storage modulus were unaffected by removal of minor components.     

Evaluation of force deformation data as indices to hydrocolloid gel strength and perceived texture

Yield stress and differential strain have been tested as indices to compare the strength of three different gelling systems with a wide range of mechanical behaviour. Differential strain index was useful because it requires only simple and inexpensive equipment to measure strain on increasing force from 1 to 2 N and it correlates well with yield stress and with several sensory textural attributes. Furthermore, it could be used on gels that do not fracture under normal compression tests, and which cannot be characterized by yield stress. However, in other cases, yield stress is interchangeable with the differential strain index.     

Biopolymers interaction elaborating using viscoelastic relaxation spectra,network parameters,and thermodynamic properties

Herein, oscillatory rheological measurements were performed to study the interaction behavior of xanthan gum‐sage seed gum blends at different ratios (SSG‐XG: 1–0, 3–1, 1–1, 1–3, 0–1), from the dynamic viscosity behavior, relaxation spectrum, fracture properties, network parameters, and thermodynamic points of view at the temperature range of 10–90°C. Then, the coefficient of the interaction of four parameters, which were obtained from the clustering technique and Han curves, were used to investigate the interaction behavior quantitatively. At 90°C, SSG showed 2.01 extent of loss modulus overshoot, which was the highest value among different gum dispersions at different temperatures, while XG showed strain softening behavior. At 10 and 90°C, SSG and 1–1 SSG‐XG showed the highest spreadability reflected by the slope of loss tangent after flow point stress (tan δ_AF ) of 0.52 and 0.40, respectively. The high values of ψ parameter, which represented the Gibbs free energy change, of both 1–3 and 3–1 SSG‐XG blends and the lowest entropy value of 1–3 SSG‐XG, suggested that the role of entropy change in incompatibility behavior of 1–3 SSG‐XG was higher than that of 3–1 SSG‐XG blend. With the increase in temperature from 10 to 70°C, the XG Euclidean distance from SSG decreased, while it increased from 70 to 90°C and showed the highest Euclidean distance with XG at 10°C (3.92) and 90°C (4.05). Interaction coefficients and Han curves results showed that all blends were incompatible with the lowest antagonistic behavior for 1–1 SSG‐XG dispersion at 50°C. Often, a mixture of hydrocolloids, especially xanthan gum and a galactomannan, are employed in processed foods to modify their rheological properties and cut the cost. The synergistic/non‐synergistic effect of biopolymers mixture, which is invaluable from the practical and economical points of view, seems to be mainly induced by their thermodynamic status of interaction. Our former study showed that the thermodynamic indices of mixing could be probed by mechanical parameters. On the other hands, we found that the mechanical properties of materials are highly temperature dependent. Therefore, in this study, to better investigate the effect of temperature on the biopolymers interaction, first we classified all the thermodynamic and mechanical properties (relaxation spectrum, fracture properties, and network parameters) of hydrocolloids into four classes, then one parameter was selected randomly from each class. The selected parameters were employed to investigate the synergistic/non‐synergistic effect at all temperature ranges by determining the interaction coefficient and decide on the best interaction temperature.     

Effect of stabiliser classes (animal proteins,vegetable proteins,starches, hydrocolloids and dietary fibre) on the physicochemical properties of a model lean meat product

The effects of eleven ingredients (originating from various ingredient classes: animal proteins, plant proteins, starches, hydrocolloids and fibres) applied in two different concentrations on drip loss, rheological characteristics and hardness were evaluated in a lean meat model system. The high concentration of potato starch, insoluble citrus fibre, rice starch or pea protein significantly (P < 0.05) reduced drip losses (6.92%, 17.87%, 15.70%, 17.60%, respectively) compared to control (30.80%), while rheological measures and hardness remained unchanged (P > 0.05). Moreover, the addition of low concentrations of soluble citrus fibre did not significantly affect hardness (4.11 N), whereas its inclusion at high concentrations had a significant effect on the final hardness (7.17 N). Among all the tested ingredients, xanthan presented the lowest drip loss value (0.12% and 0.40% for high and low concentration, respectively). Finally, gelatine did not show any differences in water holding capacity, storage modulus nor hardness compared with the control group.     

乙基纤维素对油脂流变性质和凝胶特性的影响

将不同黏度和质量分数的乙基纤维素(EC)添加到大豆油中,研究EC凝胶剂在油相中的流变性能、凝胶网络结构稳定性、硬度和液态油脂损失率。结果显示,EC油相溶液属于假塑性流体,当EC黏度为7~100 m Pa·s,溶液表观黏度呈现增大趋势,当EC黏度为200 m Pa·s时,溶液表观黏度下降;随着EC质量分数增加,溶液表观黏度逐渐增大,并出现凝胶化。其中,当EC质量分数为8%时,EC100凝胶网络对振荡频率的稳定性最好。质构分析显示,凝胶硬度的变化趋势与其网络结构稳定性相一致,EC100凝胶的硬度达到最大175.94 g,同时EC100凝胶的油相损失率最低,仅为3.14%,表明稳定的凝胶网络结构有利于更好地截留液态油。     

超声波对肌原纤维蛋白理化和质构特性的影响

目的:研究超声波功率:0、100、200、300、400、500 W对肌原纤维蛋白(myofibrillar proteins,MP)理化与质构特性的影响。方法:取活AA鸡屠宰,提取MP,用超声波处理MP然后制成热诱导凝胶。结果:随着超声功率的增加,MP粒径从1914.67(0 W)显著降低至624.50(500 W)(p<0.05)而溶解度从8.15%(0 W)显著增加至15.50%(500 W)(p<0.05);Zeta电位绝对值从5.36(0 W)一直增加至 7.40(500 W);表面疏水性从398.63(0 W)缓慢增加至 526.11(200 W)后快速增加至772.29(500 W);MP凝胶的硬度先从30.10 g(0 W)迅速增加至51.40 g(200 W)而后缓慢降低至49.40 g(500 W);超声波处理功率为200 W时,动态流变特性的储能模量(G')和损耗模量(G″)的效果最好,同时MP凝胶网络结构致密,网孔均匀。相关性分析结果表明,超声波功率与MP理化特性(粒径、溶解度、电位绝对值和表面疏水性)显著相关(p<0.05)而与质构特性(硬度)相关性不显著(p>0.05)。结论:超声波显著影响MP的理化特性,对质构特性影响较小。     

Application of a Depth Sensing Indentation Hardness Test to Evaluate the Mechanical Properties of Food Materials

ABSTRACT: A depth sensing indentation hardness test with an associated analysis is described as a convenient and simple technique for characterizing mechanical properties of food materials, such as hardness (H), elastic modulus (E), and an elasticity index (I_E), which represents the ratio of elastic to total deformation. Storage modulus (G') and loss tangent (tan§) of the selected model food material, a whey protein concentrate (WPC) gel, have also been determined using an oscillatory dynamic testing. Fractal dimension (D) and strain rate (or frequency) exponent (n) of the WPC gels were determined using both the indentation and dynamic test results. A good correlation between the results from the indentation and the dynamic tests was established. The effects of protein concentration, deformation rate, and chemical treatment on the mechanical properties of the WPC gels were clearly illustrated using the indentation test.