动态超高压微射流均质对大米蛋白功能特性的影响

以大米蛋白为原料,在不同料液比(1∶100~12∶100)和不同p H(2~12)的条件下,采用动态超高压微射流进行均质处理,研究不同均质压力(40~200 MPa)和均质次数(1~5次)对大米蛋白功能特性(溶解性、乳化性及稳定性、起泡性及稳定性和粘度)的影响。结果表明:不同料液比和不同p H的大米蛋白溶液经动态超高压微射流均质后其溶解性、起泡性、粘度均有显著的提高,而不同料液比和不同p H的大米蛋白溶液的起泡稳定性均无显著的提高。不同p H的固定料液比(3∶100)大米蛋白溶液经动态超高压微射流均质后其乳化性及稳定性有显著的改善,而不同料液比(尤其是料液比较高时)的固定p H(p H=7)大米蛋白溶液的乳化性及稳定性无显著性改善。均质压力对固定料液比(3∶100)和p H(p H=7)大米蛋白溶液的溶解性、乳化性及稳定性、起泡性、粘度的提高影响显著,而对其起泡稳定性无显著性作用。均质次数对固定料液比(3∶100)和p H(p H=7)大米蛋白溶液的溶解性、乳化性稳定性、起泡性及稳定性、粘度的提高影响显著,而对其乳化性无显著性作用(1~3次),甚至在均质次数较多(4~5次)时有负面性影响。     

高压均质技术提高烟用料液稳定性

  目的  为改善烟用料液的均一性,避免分层、沉淀产生,运用高压均质技术提高料液的稳定性。  方法  通过选取不同的均质压力、均质次数探讨高压均质对料液稳定系数、离心沉淀率、颗粒粒径、烟草提取物粘度及颗粒沉降速率的影响。  结果  :（1）随着均质压力的升高,料液的稳定系数先增加后下降,离心沉淀率减小后又增大,均质压力120 MPa时料液稳定性较好;（2）随着均质次数的增加,料液的稳定系数增加,离心沉淀率下降后上升,根据回归分析的结果,均质次数7次时料液稳定性较好;（3）增大均质压力至150 MPa,料液颗粒粒径显著减小（均质前:1.02 μm;均质后:0.4 μm,P < 0.01）,增加均质次数对料液颗粒粒径无显著影响;（4）均质次数较均质压力对料液烟草提取物粘度的影响更为显著;（5）增加均质压力至120 MPa,颗粒在料液中的沉降速率减小约45%（均质前:1.98 μm/s;均质后1.07 μm/s,P < 0.05）。  结论  高压均质技术可有效提高烟用料液均一、稳定性。      

浓缩和酸化对番茄汁质量的影响

本文研究了不同热破碎温度和时间对番茄汁粘度的影响，及浓缩过程中番茄汁色泽和粘度的变化，给出了浓缩时间、浓缩番茄汁的可溶性固形物含量和浓缩番茄汁的ａ／ｂ值间的回归方程；并探讨了酸化保存番茄汁的可能性。     

均质与热处理对脱脂搅拌型酸奶的流变性影响

就部分工艺条件对脱脂搅拌型酸奶的流变性影响进行了研究。结果表明,随着乳固体含量的增高,酸奶的粘度增高,但当乳固体含量增加到11．5％或13．0％时,酸奶的粘度并无显著提高;乳固体为10％时,抗剪切能力最好。在蛋白质含量不变的情况下添加乳清粉,用质量分数为0．41％乳清粉代替1％脱脂奶粉制得的酸奶,其抗剪切能力明显比全部用脱脂奶粉制得的酸奶好。均质和热处理条件是影响酸奶粘稠度的重要因素。均质的最佳压力为20Mpa,温度为60℃。原料乳的最佳条件是95℃、5min,经过这样处理的原料乳酪蛋白在酸奶中可以完全凝固,乳清蛋白因充分受热而完全变性沉淀,可以使搅拌型酸奶的粘度增加,抗剪切能力也比较好。     

不同均质工艺处理对巴氏杀菌乳脂肪球膜蛋白质组成的影响

乳脂肪球大小和膜蛋白组分的变化决定了脂肪球稳定性,从而影响巴氏杀菌乳在贮藏期内的品质稳定性。本研究通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和液相色谱-质谱联用法分析不同预热温度（50、60、70?℃）和不同均质压力（20、30、40、45?MPa）对脂肪球膜蛋白的影响,并通过稳定性分析仪探究脂肪球膜蛋白变化与稳定性的关系。结果表明,均质工艺对脂肪球膜蛋白种类无显著影响,但对脂肪球膜蛋白的含量有一定影响：黄嘌呤氧化还原酶（xanthine dehydrogenase/oxidase,XO）、嗜乳脂蛋白（butyrophilin,BTN）、脂肪滴结合蛋白（adipophilin,ADPH）在预热60 ℃时的含量最低,黏液素（mucin 1,MUC1）在预热60 ℃时的含量最高,脂肪酸结合蛋白（fatty acid binding protein,FABP）、组织糖蛋白高碘酸烯夫6/7（periodic acid Schiff 6/7,PAS6/7）的含量随着预热温度的升高而减少,组织糖蛋白高碘酸薛夫IV（cluster of differentiation 36,CD36）的含量随着预热温度的升高而增多;XO、PAS6/7、BTN、ADPH、FABP在均质压力40 MPa时含量最低,CD36的含量随均质压力的增加而减少;脂肪球膜蛋白构成中,牛血清白蛋白（bovine serum albumin,BSA）、αs1-酪蛋白（casein,CN）和β-CN含量增加,其中BSA含量增加最明显。综上,推测均质工艺导致αs1-CN、β-CN和BSA组分参与了脂肪球膜的构建,并对脂肪球稳定性产生了积极的影响。     

贮藏时间对超高压处理鲜榨番茄汁品质的影响

以热处理(100℃处理5 min)作为对照,评价超高压处理(25℃和400 MPa处理30 min)鲜榨番茄汁贮藏3个月期间的品质和风味变化规律。结果显示超高压处理的鲜榨番茄汁在2个月的贮藏期内,菌落总数、霉菌和酵母菌数量均在国家食品卫生标准以内;pH值、PPO和POD活性逐渐降低;维生素C含量降低约24%,而热处理的鲜榨番茄汁中维生素C含量降低约96%;超高压处理的鲜榨番茄汁风味更加接近于番茄的原有香气,而热处理引起风味的显著性变化。因此,超高压处理的鲜榨番茄汁在2个月的贮藏期内品质和风味均优于传统热处理番茄汁。     

番茄汁饮料加工技术研究

本文以番茄为原料,研究生产番茄汁饮料的工艺技术,包括不同破碎方法及不同破碎温度对番茄汁粘度的影响,同时对番茄汁饮料在加工贮藏过程中极易分层和色泽变暗的不稳定现象进行了研究,最后确定了一组生产番茄汁的最佳工艺参数.     

高压均质压力对烟用料液中致香物质含量的影响

  目的  研究高压均质压力对烟用料液中主要致香物质含量的影响,为该技术在烟用料液生产加工中的应用提供数据支撑。  方法  分别设定不同的均质压力（0 MPa、60 MPa、90 MPa、120 MPa、150 MPa）对同一批次烟用料液进行高压均质处理,检测均质后料液中的致香物质,并利用单因素方差分析、回归分析和聚类分析研究不同均质压力条件下料液中致香物质含量的差异性及变化趋势。  结果  (1) 当均质压力从0 MPa升高至150 MPa,对所检测到的22种主要致香物质含量均产生了显著性影响,其中有18种致香物质含量呈逐渐增加的趋势。(2)在实验范围内,随着均质压力的升高,料液中的各类致香物质含量及其总量呈逐渐增加的抛物线型变化趋势,且回归方程的拟合度均较高（R2≥0.8778）。(3)几个不同均质压力处理后的料液样品可以分为中低压（60 MPa和90 MPa）和高压（120 MPa和150 MPa）两类,说明当均质压力由90 MPa升高至120 MPa后,对料液中的整体致香物质含量产生了非常显著的影响。  结论  高压均质技术可以有效提升烟用料液中的小分子致香物质含量。验证实验结果表明,高压均质技术主要通过促进料液中大分子物质的降解或水解反应,从而增加了小分子物质的含量。      

红外预热处理对压榨紫苏籽油品质 及抗氧化活性的影响

采用不同温度、时间红外预热处理紫苏籽,探讨其对压榨紫苏籽油品质（包括理化指标、脂肪酸组成、褐变程度、活性成分含量）、抗氧化活性及氧化稳定性的影响。结果表明：经红外预热处理制备的紫苏籽油理化指标、脂肪酸组成均符合LS/T 3254—2017《紫苏籽油》要求,脂肪酸组成与未经红外预热处理的无显著差异,且180 ℃红外预热处理30 min能够显著提高紫苏籽油多酚和黄酮含量、抗氧化活性及氧化稳定性（P＜0.05）。此外,相关性分析表明紫苏籽油褐变程度、多酚含量、黄酮含量与抗氧化活性、氧化稳定性呈极显著或显著正相关（P<0.01,P＜005）。180 ℃、30 min适宜作为紫苏籽红外预热处理条件,研究结果为紫苏籽油的制备提供了参考依据。     

超高压协同中温处理对番茄汁中番茄红素和总VC 含量的影响

探讨超高压协同中温加工对番茄汁中番茄红素和总VC 含量的影响。番茄汁在温度为33.5℃,压力为469.2MPa,时间为14.0min 的条件下处理,番茄红素含量显著增加,但番茄红素顺反异构体变化不明显;VC 含量变化不显著。     

EFFECT OF HOMOGENIZATION PRESSURE ON CONSISTENCY OF TOMATO JUICE 1

Pressurized homogenization of tomato juice at room temperature (28C) leads to an increased consistency and reduced serum separation in the juice. Percentage increase in consistency (as measured by Libby's tube) of hot processed juice from different cultivars ranged from 95 ± 3 to 282 ± 13 s. The magnitudes of change in consistency and serum spearation of cold processed juice due to homogenization were smaller than those for hot processed juice. Increases in consistency of cold processed juice ranged from 42 ± 4 to 213 ± 10 s. Consistency in all the samples increased with increasing pressure of homogenization up to a pressure of 3000 psi, above which it became constant. Homogenization of juice at higher temperature resulted in a very small increase in consistency. However, the magnitude of increase in consistency decreased with increasing temperature. Serum separation slightly increased at higher pressure of homogenization, after reaching a minimum with increasing pressure initially. In general, the juice with higher initial efflux and serum viscosities showed a larger increase in consistency and greater reduction in serum separation.     

VISCOSITY AND QUALITY OF TOMATO JUICE AS AFFECTED BY PROCESSING METHODS

ABSTRACT

Quality and viscosity of tomato juice is strongly governed by mechanical and thermal abuse during processing. The effect of processing and storage duration on the viscosity and quality parameters of tomato juice was evaluated in the present work. Tomato juice was obtained by two different methods, normal method (NM) and variable method (VM), and was heated by both conventional and microwave hot break treatments. Tomato juice was evaluated for various quality characteristics including precipitate weight ratio, degree of serum separation (DOSS), Brookfield viscosity, lycopene levels, vitamin C, phenols and antioxidant activity. Changes observed in several quality parameters during storage were statistically insignificant. The methods and processing had the greatest contribution toward viscosity, whereas storage duration had no significant effects. Viscosity parameters viz precipitate weight, DOSS and Bostwick consistency revealed that juice processed by VM was more viscous than that of NM, irrespective of the hot break processing used. Ascorbic acid and lycopene content varied significantly with mechanical methods and processing conditions. However, phenolic content and antioxidant activity remained stable. The variable process represents an improvement over the conventional by enabling tomato processors to improve the consistency of the tomato product.

PRACTICAL APPLICATIONS

Quartering or slicing tomatoes followed by hot break processing techniques can significantly improve the quality of tomato juice in terms of reduced degree of serum separation and precipitate weight ratio. The modified technology could be considered as a viable and economical method for small‐ and medium‐scale tomato processors with limited resources and facilities at their disposal.

     

Pectin-Protein Interaction in Tomato Products

The pH influenced the viscosity of a model system of tomato product which consisted of citrus pectin and bovine serum albumin. The viscosity change was completely reversible depending on the pH. The same pH effect was observed in tomato products. Since the amino acid compositions of proteins suggest that the electrostatic property of water-soluble protein fraction from tomato juice can be similar to that of bovine serum albumin, the comparison of pH effects indicates that pectin-protein interaction may be involved in consistency of tomato products. Denaturation of protein may result in a decrease in the serum viscosity during processing.     

THE ROLE of PULP INTERPARTICLE INTERACTION IN DETERMINING TOMATO JUICE VISCOSITY

Pulp interparticle interaction plays a major role in determining the viscosity of tomato juice. Indices of second order and of compounded high order interparticle interaction have been evaluated by diluting tomato juice samples with their own serum, and determining the slope of the reduced viscosity curves at the very dilute and at the original concentration regions, respectively. the second order interaction index, reflecting the behavior of a pair of colliding particles, has practically a similar value for samples having the same process history. On the other hand, tomato juice samples differ markedly in their value of the interaction index describing the effect of high order interparticle interaction on the viscosity at the original juice concentration. the higher that value, the higher the viscosity. the value of this index decreases by concentrating the tomato juice and increases by homogenization. It has a maximum value at pH 4–4.5 and most importantly it is greatly dependent on the mechanical abuse history of the juice. Enzymatic depolymerization of the soluble and especially the insoluble pectin markedly reduces the value of the interaction index, indicating that pectin plays a major role in determining the level of that interparticle interaction.     

Effect of high pressure homogenization (HPH) on the rheological properties of a fruit juice serum model

High pressure homogenization (HPH) is a non-thermal technology that has been widely studied as a partial or total substitute for thermal food processing. The present work evaluated the effect of HPH on the rheological properties of a fruit juice serum model, designed to be similar to tomato juice serum. Product viscosity decreased due to the increase in homogenization pressure, and could be modelled well using two functions (power-sigmoidal and exponential; R² > 0.98). The serum model processed at 200 MPa showed a viscosity decrease of 20% when compared to the original. Since fruit juice rheology is defined by the interactions occurring between the dispersed phase (suspended particles) and the solution (serum), the expected fruit juice behaviour was then discussed.     

EFFECTS OF pH ON QUALITY OF STORED TOMATO JUICE

Tomato juice was prepared by the hot-break method and filled hot into cans containing sufficient concentrated HCl to adjust pH to 4.0, 3.5, 3.0, 2.5 and 2.0. Controls were also prepared with no HCl added. Product was stored at ambient (18–22°C) and 40°C up to 3 months. As pH decreased below 4.0, consistency also showed a significant decline through pH 2.0. At the same time there was no apparent pH effect on serum viscosity. Further studies indicated that this effect was noticeable after 4 hr, at pH 3.0 to 5.0. Addition of as much as 1% NaCl to tomato juice had no effect on consistency of tomato juice. Lightness (Hunter color L ) decreased with pH after 3.5, redness (a_L) decreased after pH 4.0, and yellowness (b_L) decreased after pH 3.0. All storage effects were more profound at the higher temperature. The storage of tomato juices at pH less than 4.0 does not appear to be advantageous to the processor.     

取汁方式对热破碎番茄汁品质的影响

研究了2种取汁方式在不同的热处理条件下对热破碎番茄汁品质的影响。结果表明,破碎-加热-打浆取汁方式(简称为BHJ)的番茄汁粘度、果胶含量和番茄红素含量显著高于打浆取汁-加热的取汁方式(简称为JH),但取汁方式对汁的色差影响不大。在本试验范围内,BHJ取汁的番茄汁品质优于JH取汁。     

Tomato Product Quality from Transgenic Fruits with Reduced Pectin Methylesterase

Juice from transgenic tomato (Lycopersicon esculentum cv Rutgers) fruits with reduced levels of pectin methylesterase (PME) activity due to the expression of a PME antisense gene exhibited improvement in quality. The percentage increase in juice from transgenic fruits over that of juice from wild type Rutgers ranged between 5.1–5.3 for total solids, 3.8–6.1 for soluble solids, 70–80 for efflux viscosity, 180–220 for serum viscosity and about 50 for precipitate weight ratio. Time of harvest had no effect on quality of juice. Ketchup prepared from transgenic fruit juice had a lower Bostwick value, reduced serum separation and high serum viscosity compared to ketchup from parental Rutgers.     

Frozen Concentrated Orange Juice (FCOJ) Processed by the High Pressure Homogenization (HPH) Technology: Effect on the Ready-to-Drink Juice

The high pressure homogenization (HPH) process can be used to reduce the consistency of frozen concentrated orange juice (FCOJ), which is highly desirable in industrial processing due to the reduction in energy costs. The production of FCOJ is almost entirely destined to obtaining the reconstituted (ready-to-drink (RTD)) juice. Consequently, this study aimed to evaluate the effect of the HPH processing on the ready-to-drink juice. FCOJ (66°Brix) was processed by HPH up to 150 MPa and then diluted to 11°Brix for evaluation. The RTD juice was evaluated by pulp sedimentation, instrumental colour, turbidity (serum cloudiness), rheological properties and sensorial perception. The HPH process decreased the absorbance of the serum phase, which was related to the disruption of the suspended particles. Further, the process slightly reduced the RTD juice viscosity. However, the HPH showed no effect on the product colour, pulp sedimentation behaviour and sensorial perception (visual aspect, odour, flavour, viscosity, overall liking). Therefore, it was concluded that the HPH process can be used to promote desirable effects on FCOJ, without affecting the RTD juice properties.     

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。