高压均质时间对牛骨白汤乳化稳定性的影响

目的 研究不同高压均质时间(4、8、12、16、20、24 min)作用下对牛骨白汤乳化稳定性的影响。 方法 以牛骨素、牛骨油为主要原料制备牛骨白汤,利用紫外分光光度计、纳米电位仪、粘度计、光学显微镜和拉曼光谱仪测定不同均质时间处理的牛骨白汤的乳化活性、乳化稳定性、粒径、多分散系数、Zeta电位、黏度、微观结构以及蛋白二级结构。结果 均质时间增加可显著提高乳化活性、乳化稳定性、黏度、Zeta电位、无规卷曲和β-转角(P<0.05), 降低粒径、多分散系数、α-螺旋和β-折叠(P<0.05),均质时间为12 min时,乳化效果最佳,超过12min,乳化效果下降。结论 均质时间为12 min时对牛骨白汤产生的乳化效果最佳,解决了牛骨白汤均质过程中的技术问题,为食品工业化生产牛骨白汤等复合调味 品提供理论依据和技术支持。     

微射流均质改善热压榨花生粕分离蛋白乳化特性的研究

以热压榨花生粕中提取的花生分离蛋白为原料,采用微射流高压均质进行改性处理,以乳化活性、乳化稳定性、粒度分布和离心乳析率为评价指标,系统研究了不同微射流均质压力对花生分离蛋白乳化特性的影响,并初步探讨了乳状液微观聚集状态和花生分离蛋白宏观乳化特性的相互关系.结果表明:随着均质压力增大,乳化活性和乳化稳定性均呈现先增大后减小趋势;乳化活性和乳化稳定性增大,相应乳状液粒径变小,离心乳析率下降;120MPa是改善花生分离蛋白乳化特性的优选条件.显微镜观察发现,宏观乳化特性改善时,体系微观聚集体减少,120MPa改性的花生分离蛋白制备的乳状液没有发生明显聚集.     

DHA乳状液制备工艺优化及氧化稳定性的研究

以二十二碳六烯酸(Docose Hexaenoie Acid, DHA)微藻油微胶囊化过程中形成的乳状液为研究对象,研究乳状液制备工艺条件及氧化稳定性。利用透射光浊度法和电导率法测定乳状液的稳定性,研究预乳化时间、乳化温度、均质压力、均质级数对乳状液稳定性的影响。以乳状液稳定性和表面张力为评价指标,在单因素试验基础上采用正交试验对乳状液制备工艺进行优化,制备后进行微胶囊包埋,分析了DHA微藻油微胶囊的氧化稳定性。结果表明,乳状液制备的最佳工艺为乳化温度50℃、均质压力30 MPa、预乳化时间3 min,2级均质,在此条件下,透射光浊度法测定得到乳状液稳定性为8.75%,表面张力为20.5 mN/m。乳状液制备工艺优化后得到的DHA微胶囊氧化稳定性得到显著提高。     

磷脂微胶囊化乳化液稳定性的研究

本文主要研究磷脂微胶囊化过程中乳化液稳定性的影响因素、乳化液稳定性表征及磷脂微胶囊化乳化液制备条件.随着乳化液中干物质浓度增加,乳化液稳定性增强,浓度超过35%时稳定性减弱;干物质浓度与乳化液黏度呈指数关系.芯材(磷脂)含量低于70%时,芯材含量的变化对乳化液稳定性影响不显著.乳化温度的升高有利于乳化稳定性.均质时间的延长和压力的增加都会增强乳化稳定性,但乳化时间超过10 min,压力超过45 MPa后,均质条件的变化对乳化稳定性的作用甚小.试验结果证明:乳化液微粒大小、黏度、电导率、吸光度能有效表征磷脂微胶囊化乳化液的稳定性.磷脂微胶囊化稳定乳化液的制备条件:干物质含量30%,乳化温度40℃,芯材(磷脂)含量60%,乳化温度40℃,均质压力45 MPa,均质时间10 min,乳化剂为吐温与司班的混合物(HLB 8),乳化剂添加量0.1%.     

均质条件对辛烯基琥珀酸淀粉酯制备的水油乳化体系粒径的影响研究

通过离心法、分光光度计法、电导率法证明了辛烯基琥珀酸淀粉酯具有良好的乳化性和乳化稳定性。以低黏度辛烯基琥珀酸淀粉酯为乳化剂,以大豆油为乳化对象,利用激光粒度仪和光学显微镜探讨了均质转速、均质温度、均质时间、均质pH对辛烯基琥珀酸淀粉酯制备的乳化体系粒径的影响。结果表明:均质pH对乳化体系粒径具有显著的影响;均质时间越长和均质转速越大,乳化体系的粒径越小;均质温度对乳化体系粒径影响较小。     

基于大豆分离蛋白的脂肪模拟工艺条件优化

为获得与油脂感官特征相近的大豆分离蛋白基脂肪替代物,综合运用单因素和Box-Behnken试验设计,以大豆分离蛋白添加量、魔芋胶添加量、加热温度、加热时间、均质时间为考察因子,以复合体系的黏度及乳化稳定性为响应值,确定制备大豆分离蛋白基脂肪替代物的最佳工艺条件。结果表明,最佳工艺条件为大豆分离蛋白质量分数8%、魔芋胶质量分数0.08%、加热温度79.8 ℃、加热时间13 min、均质时间40 s,此条件下复合体系的黏度为45.94 mPa·s,乳化稳定性为74.49 min,与市售植物油相当。     

辛烯基琥珀酸淀粉酯乳化白藜芦醇的工艺研究

以辛烯基琥珀酸淀粉酯为乳化剂,白藜芦醇为药物模板,利用剪切乳化结合高压均质技术制备白黎芦醇乳液,单因素实验考察了剪切乳化过程中乳化剂用量、乳化时间、乳化温度和白藜芦醇加入量对初乳液稳定性的影响,获得制备白藜芦醇初乳液的优化工艺为SSAS加入量4%,白藜芦醇加入量0.2%,乳化温度50℃、乳化时间20 min,此条件下SSAS制备的白藜芦醇初乳液的稳定性较好。在剪切乳化优化工艺条件下考察了高压均质压力和均质次数对白藜芦醇乳液粒径分布的影响,结果表明,高压均质对辛烯基琥珀酸淀粉酯制备白藜芦醇乳液的粒径分布有显著影响,均质压力在40~100 MPa、均质2次的条件下,乳液的粒径分布较好。     

高压均质对大豆β-伴球蛋白富集组分乳化特性的影响

研究了高压均质对大豆β-伴球蛋白(7S)富集组分乳化活性、乳化稳定性、粒度分布和乳析稳定性的影响。结果表明:与未均质相比,均质处理使7S富集组分乳化活性降低,但可提高其乳化稳定性;乳化活性随均质压力的升高而降低,均质次数对其影响不明显,随着均质压力的升高和均质次数的增多7S富集组分乳化稳定性逐渐提高;高压均质改性的7S富集组分制备的乳状液粒径更小,并且乳析率下降;均质压力不变时,一次均质的7S富集组分比2次均质的7S富集组分形成的乳状液粒径更大,但乳析率降低。     

羧甲基纤维素钠及酸性乳饮料加工工艺对其稳定性及粒径分布的影响

研究了羧甲基纤维素钠（CMC）及酸性乳饮料加工工艺对其稳定性及粒径分布的影响。通过离心沉淀法检测酸性乳饮料的稳定性．对影响稳定效果的主要加工工艺进行了试验。同时测定了这些加工工艺对产品粒径分布的影响,并分析了体系粒径分布与产品稳定性之间的关系。结果表明,CMC添加量、pH值、均质压力、调酸温度等因素都会影响酸性乳饮料的稳定性和粒径分布,其中CMC添加量和均质压力对结果影响明显,调酸温度次之,pH值对结果影响最小。     

斐林氏法测定还原糖的误差分析

本研究根据斐林氏法测定还原糖的基本原理，采用自动控制系统调整反应条件，定量分析了加热温度、加热时间、测定速度、搅拌力度对测定结果的影响。     

外界因子对提取双低菜籽粕分离蛋白效果的影响

通过鉴别设计法(SD)对影响提取双低菜籽粕分离蛋白效果的外界因子,如pH、料液比(g/ml)、提取温度、振荡时间、离心时间、离心转速等关键因子进行考察与评价。结果表明:pH、料液比(g/ml)和提取温度对提取双低菜籽粕分离蛋白影响显著,振荡时间、离心时间和离心转速对提取双低菜籽粕分离蛋白影响不显著。     

35—THE TREATMENT OF WOOL-SCOURING EFFLUENT: CENTRIFUGATION STUDIES

An account is given of an investigation in which an attempt was made to isolate the reasons for the apparently inevitable limitation in the recovery of grease from wool-scouring liquors in a centrifuge, as a prelude to the development of a process to treat effluent discharged from the primary centrifuge before biological processing.

The recovery of grease with a centrifuge from a wool-scouring liquor that has not been excessively agitated is shown to depend primarily on the composition of the disperse-phase particles. The composition of those particles not capable of being separated in a centrifuge is almost solely dependent on the quantity and density of detergent employed in scouring. Excessive agitation of the scouring liquor dramatically reduces recovery and should be strictly avoided.     

三足离心机振动模型的建立

三足离心机被广泛用来分离固体和液体的混合物,其工作转速一般在2 000 r/min,但是对于颗粒更细的混合液的离心效果不是很好。文章分析离心机组成结构,对分部件分类描述,并推导出相应的动能描述形式。进而在分析悬挂力的基础上,应用第二类Lagrange方程,建立了离心机的动力学模型。在此基础上,采用四阶Runge—Kutta求解整机的运动轨迹,并验证了该动力学模型的正确性。从而为三足离心机减振抑噪的进一步研究提供了理论依据。     

46—THE EXTRACTION OF WATER FROM COTTON-YARN PACKAGES BY CENTRIFUGAL FORCE. PART I: SPINNING IN A BASKET CENTRIFUGE

A study is reported of the removal of moisture from cotton-yarn packages by centrifugal force in the basket type of centrifuge or hydro-extractor. Equations describing the influence of time, centrifugal force, and package characteristics on the rate of moisture removal are developed.     

MEASURING THE WATER HOLDING CAPACITY OF NATURAL ACTOMYOSIN FROM CHICKEN BREAST MUSCLE IN THE PRESENCE OF PYROPHOSPHATE AND DIVALENT CATIONS

The water holding capacity (WHC) of natural actomyosin (NAM) extracted at pH 9.2 in 0.6M KCl was measured in the presence and absence of various combination of sodium pyrophosphate (PP_i), MgCl₂ and CaCl₂ using a modification of the classical centrifugation technique. Samples, in the presence of 0.15M NaCl and 20 mM sodium phosphate buffer pH 6, were spun at 30,900 X G (as measured at the bottom of the centrifuge tube) for 15 min at 2–4C. The results show that between 17 and 20 g water/g protein were bound over a wide range of NAM concentrations. In each case the amount of water held by the experimental sample was equal to or less than the amount held by a control run at the same time: 5 mM PP_i= 100%; 5 mM PP_i+ 5 mM MgCl₂= 58%; 5 mM MgCl₂= 85%; 5 mM PP_i+ 5 mM CaCl₂= 68% and 5 mM CaCl₂= 92% of the control. Thus polyphosphate addition in the presence of divalent cations lowers the WHC of NAM. The absence of the organized structure of muscle in NAM is postulated to be the reason that polyphosphate plus divalent cation reduced WHC in these samples. A series of preliminary experiments were run in order to determine the effect of experimental parameters on WHC.     

推料离心机液压调节推料次数的研究与实践

文章对P系列双级推料离心机推料次数调节的液压调速系统进行了研究,分析了离心机的液压回路,指出用节流阀旁路节流来调节推料次数会降低系统的最大承载能力,以及调节的推料次数范围较小的缺点。通过对液压调速阀的研究,指出用调速阀旁路节流对推料次数进行调节,系统最大承载压力不会因调速阀的开度增大而减小,同时推料次数的调节范围也加大了,从而使离心机更能适应物料的波动,具有节省能耗的效果。     

EFFECT OF LUBRICATION ON THE COMPRESSION BEHAVIOUR OF CHEESE AND FRANKFURTERS

Cylindrical samples of cheese and frankfurters were subjected to a 50% uniaxial compression between flat plates and artificial molars, mounted on a Texture Analyser, operating at two speeds, with and without lubrication. At both speeds and with both types of probe the maximum force was less for the lubricated probes than the unlubricated probes. In all cases the maximum force recorded at the higher speed was greater than at the lower speed and greater when plates were used than when teeth were used. Through observations made during the testing and from photographs taken, it was concluded that the frictional effect of the cusps on the molar teeth was greater than the effect of lubrication. Observations made when samples were compressed between molar teeth in the mouths of panellists confirmed the conclusion that compression of foods in the mouth follows the nonlubricated pattern despite the lubrication provided by saliva.     

EFFECTS OF PHYSICAL PROPERTIES AND ORAL PERCEPTION ON TRANSIT SPEED AND PASSING TIME OF SEMILIQUID FOODS FROM THE MID-PHARYNX TO THE HYPOPHARYNX

The results of two sensory analyses, using healthy young individuals as assessors and semiliquid foods with markedly different physical properties as samples, were compared. One analysis required the assessors to perceive the food texture by oral perception alone and to use it as a basis for predicting the ease of swallowing of the bolus samples (i. e., the mobility of the samples through the pharynx) without actually swallowing the samples. The other analysis required the assessors to evaluate the mobility of the bolus samples through the pharynx, by actually swallowing them. Comparison of the results implied that human beings predict how easy it is to swallow a bolus (i. e., the mobility of the bolus through the pharynx) by perceiving in the oral cavity the texture of the food. Examinations were also made on the relationship between the evaluation of mobility of the bolus through the pharynx obtained by sensory analyses, and the transit speed and passing time of the bolus samples obtained by videomanofluorography. It was recognized that the front end speed was fast for semiliquid food samples that were soft and easy to swallow (and therefore easy to move through the pharynx), whereas the front end speed was slow for semiliquid food samples that were hard and difficult to swallow (and therefore perceived as being difficult to move through the pharynx.) These findings suggest that human beings' perception of the ease of swallowing of semiliquid food is closely related to the front end speed of the bolus. No significant difference was found among samples, either in the tail end speed of the bolus samples, or in the passing time from the front end to the tail end of the bolus samples. These results imply that, through some kind of swallowing efforts, healthy individuals are controlling the passing time through the pharynx of boluses with markedly diflerent physical properties, so that the time remains constant.     

20—THE INFLUENCE OF THE AIR PRESSURE AT THE ROTOR-CLEANING DEVICE OF ROTOR-SPINNING MACHINES ON THE PROPERTIES OF COTTON OPEN-END-SPUN YARNS

The effect of under-pressure at the entrance to the rotor-cleaning device on the properties of cotton open-and-spun yarns is studied in relation to the opening-roller speed, the total draft, and the rotor geometry. It is shown that there are differences in behaviour between the three rotor types studied; these chiefly concern yarn unevenness and imperfection content.

The air pressure at the entrance to the rotor-cleaning device influences, to a small extent, yarn elastic characteristics and, to a greater extent, yarn irregularity and imperfection content for one rotor type (type J). The opening-roller speed affects only certain aspects of yarn unevenness and imperfection content for one of the rotors (type F). whereas the total draft, allied to the yarn linear density, is the factor that has most influence on yarn parameters. The presence of an optimum draft zone between about 90 and 100 is confirmed.     

应用熔体指数仪研究聚丙烯流变特性

通过比较不同载荷和温度下聚合物熔体单位时间内的挤出量和挤出物直径，预测其流变特性，应用国产的标准熔体指数仪，考察了温度和载荷对几种熔体指数不同的聚丙烯熔体流动速率的影响。通过对实验数据的统计分析，采用二元非线性回归分析的方法，发现聚丙烯的熔体流动性与压力和温度服从二元指数函数关系，并且不同熔融指数的聚丙烯其熔体流动性对温度和压力的敏感性是不同的，结合高聚物的加工理论，对指导聚丙烯的加工有一定的意义