不同乳粉溶液超高压处理后理化性质的变化

对超高压处理后全脂乳粉、脱脂乳粉和乳清粉配制成的乳蛋白质溶液的理化性质变化进行了研究，４００ＭＰａ处理１５ｍｉｎ后，全脂乳粉液的浊度下降很少，乳清粉液浊度的下降也不很明显，而脱脂乳粉液浊度的下降则非常明显；超高压处理后的全脂乳粉液离心时脂肪的上浮量与处理压力呈正比。超高压处理后三种溶液的粘度均提高，其中以脱脂乳粉液增加的较为明显。处理后的全脂和脱脂乳粉液酸化时凝乳的得率有所提高，但全脂乳粉的凝结时间在＞２００ＭＰａ压力处理后会增加，而脱脂乳粉液的凝结时间在＞２００ＭＰａ时明显减小。这些结果显示，超高压处理后，乳粉溶液中脂肪球凝聚而增大。溶液中脂肪、糖等成分的存在，使超高压处理后蛋白质溶液理化性质的变化有明显不同。     

超高压处理对豆浆凝胶特性的影响

豆浆在２００～５００ＭＰａ超高压处理后,葡萄糖酸内酯点浆后加热时开始出现凝结的时间变迟,所形成的豆腐持水性升高、质地细腻,形成豆腐后的豆清中氮的含量降低,豆腐的得率提高。超高压的作用使得豆浆中蛋白质发生解聚和伸展,暴露了内部的－ＳＨ基团并促进二硫键的形成或交换,有利于豆浆形成豆腐。压力所导致的凝胶效果随压力的增大而增加,当压力≥３００ＭＰａ时即可使点浆后的豆浆形成质地细腻,持水性良好的豆腐凝胶。２００ＭＰａ超高压处理对豆腐的影响不大,但４００ＭＰａ超高压处理后,豆腐略有收缩并析水,豆腐的持水性下降、硬度略有增加。     

超高压处理对平浆凝胶特性的影响

豆浆在２００－５００ＭＰａ超高压处理后，葡萄糖酸内酯点浆后加热时开始出现凝结的时间变迟，所形成的豆腐持水性升高、质地细腻，形成豆腐后的豆清中氮的含量降低，豆腐的得度提高。超坑压的作用使得豆浆中蛋白质发生解聚和伸展，暴露了内部的－ＳＨ基团并促进二硫键的形成或交换，有利于豆浆形成豆腐，压力所导致的凝胶效果随压力的增大而增加，当压力≥３００ＭＰａ时即可使蹼浆后的豆浆形成质地细腻，持水性良好的豆腐凝胶。２     

高压对玉米淀粉糊化特性的影响

本文采用ＤＳＣ法研究了玉米淀粉经４００ＭＰａ以下的高压处理后，其糊化特性的变化。处理压力越高，保压时间越长，则糊化温度降低越大。４００ＭＰａ处理３０ｍｉｎ，糊化温度降低２．３７℃，糊化焓则在３００ＭＰａ，３０ｍｉｎ的出现最低点。     

小麦淀粉高压糊化动力学的研究

本文采用差示扫描热分析（ＤＳＣ）法测定了不同压力下处理不同时间的小麦淀粉的糊化度,计算了小麦淀粉压车湖化反应动力学参数,结果表明,科淀偻的加压糊化为一级反应,压力分别在３００ＭＰａ、４００ＭＰａ、４５０ＭＰａ其糊化速率常数０．３６、０．４５和０．５;压力对速率常数的影响可用。     

超声处理对豆浆流变学特性和微观结构的影响研究

研究豆浆经过不同超声功率(200、300、400、500、600 W)处理后,利用高速离心机、HR-1动态剪切流变仪以及激光共聚焦显微观察超声功率的改变对豆浆的持水特性、流变特性和微观结构的影响。结果表明,豆浆经过超声处理后,其持水力增大,但是超过300 W时,豆浆持水力没有显著变化;同时表现出较强的黏弹性以及剪切稀化特性,表观黏度和剪切应力也有所增加,并且随处理超声功率的增加,这种趋势愈发明显;未处理豆浆呈现油包水状态,超声处理后,豆浆的微观结构中孔隙变小,蛋白质颗粒与脂肪球均减小,且分散均匀,分子间作用力增大,蛋白与脂肪之间交联增多,乳液整体呈现水包油状态,当超声达到500 W时,体系中蛋白质将油脂包裹均匀,形成更加均一致密的凝胶网络结构,超声会对豆浆流变特性和微观结构产生积极影响。     

高静压对嗜热脂肪芽孢杆菌的杀菌作用

研究了高静压协同热处理工艺和添加溶菌酶等方法对嗜热脂肪芽孢杆菌的灭菌作用。结果表明,压力处理前的预热处理（如４５℃,２０ｍ ｉｎ）比压力处理后的热处理有更高的灭菌作用。６５℃的预热处理优于其它热处理温度（４５℃、８５℃）。微波预热处理比传统预热处理有更好的协同灭菌作用。压力处理中溶菌酶的存在有较好的协同灭菌作用。当介质中溶菌酶浓度达到２０００ＩＵ／ｍ ｌ、在３００ＭＰａ 下灭菌１５ｍ ｉｎ,嗜热脂肪芽孢杆菌残留可下降５ 个数量级。     

乳酸菌产粘菌株筛选及其产粘特性影响因素的研究

从八种乳酸菌种计２５个菌株中筛选产粘菌株，采用旋转粘度计测定其粘度值作为筛选标准，从中筛选了三株高粘菌株，二株中度粘性菌株，其平均粘度值分别为５００ＭＰａ·Ｓ和２００Ｍｐａ·Ｓ。菌株在低于其适宜生长温度时产粘显著，随着温度升高而粘度下降，干物质含量可增加其粘度，粘度大乳清杆出量少，但与保水性无确切的相关性，在刚形凝胶时粘度即达到最大，经过酶解蛋白后薄层色谱分析，初步证明是半乳糖聚合而成的低聚半乳糖     

高压下牛乳IgG的变性及稳定化作用

高压下（２００￣７００ＭＰａ）牛乳ＩｇＧ的变性及稳定化研究表明：随着蔗糖浓度的提高，ＩｇＧ在高压下的稳定性增大，并伴随ＩｇＧ最大发射波长的蓝移和荧光强度的降低。蔗糖对ＩｇＧ在高压下的稳定化作用是由于其增加了ＩｇＧ分子内部疏水交互作用，从而稳定了其三级结构。     

不泛黄白金油的研制及应用

本专题为皮革用ＤＧ白金油，以醋丁纤维素１００－２００份，丙烯酸酯２００－４００份，水１５０－２５０份，在适量的催化剂作用下，温度５０－６０℃，进行接矣合反应约４－６小时。反应后干燥物３００份，醋酸丁酯３００份，醋酸乙酯３００分，甲苯１００份，溶解后加入钛白粉１００－２５０粉，分散稳定剂若干份，研磨４小时，出料。本产品适用白色运动旅游鞋革的顶层作饰，具有不泛黄、增加白度，耐干湿擦，耐折等优点。     

High pressure homogenisation of raw whole bovine milk (a) effects on fat globule size and other properties

Although widely adopted by the chemical and pharmaceutical industries in recent years, little published data is available regarding possible applications of high pressure homogenisation for dairy products. The objective of this work was to compare the effects of conventional (18 MPa, two-stage) and single or two-stage high pressure homogenisation (HPH) at 50-200 MPa on some properties of raw whole bovine milk (approximately 4% fat). Fat globule size decreased as HPH pressure increased and, under certain conditions of temperature and pressure, HPH yielded significantly smaller fat globules than conventional homogenisation. Fat globule size was also affected by milk inlet temperature. The pH of all homogenised milk samples decreased during 24 h refrigerated storage. Total bacterial counts of milk were decreased significantly (P < 0.05) for milk samples HPH-treated at 150 or 200 MPa. Whiteness and rennet coagulation properties of milk were unaffected or enhanced, respectively, as homogenisation pressure was increased. Average casein micelle size decreased slightly when skim milk was homogenised at 200 MPa. Thus, HPH treatment has several, potentially significant, effects on milk properties.     

Structural and Textural Changes in Kinu-Tofu Due to High-Pressure-Freezing

To determine the effect of high-pressure-freezing on quality, kinu-tofu (soybean curd) was frozen at 100 MPa (ice I), 200 MPa (liquid phase), 340 MPa (ice III), 400, 500, 600 MPa (ice V) or 700 MPa (ice VI) at ca. –20°C for 90 min. After reduction to atmospheric pressure, tofu was stored 2 days at –30°C then thawed at 20°C. Texture and structure were compared with kinu-tofu frozen (–20°C, –30°C or –80°C) at atmospheric pressure (0.1 MPa). The rupture stress and strain of tofu frozen at 0.1 MPa and 100 MPa increased, but that of tofu frozen at 200 MPa and 340 MPa was similar to untreated tofu. As pressure rose above 500 MPa, rupture stress increased. The ice crystals in tofu frozen at 200 MPa ～400 MPa were smaller than in tofu frozen at 100 MPa or 700 MPa. Thus, high-pressure-freezing at 200 MPa ～400 MPa was effective in improving the texture of frozen tofu.     

Dynamics of casein micelles in skim milk during and after high pressure treatment

The effect of high hydrostatic pressure on turbidity of skim milk was measured in situ together with casein micelle size distribution. High pressure (HP) treatment reduced the turbidity of milk with a stronger pressure dependency between 50 and 300 MPa when the temperature was decreased from 20 to 5 °C, while at 30 °C (50–150 MPa) turbidity exceeded that of untreated milk. At 250 and 300 MPa turbidity decreased extremely. During pressurization of milk at 250 and 300 MPa, the turbidity initially decreased, but treatments longer than 10 min increased the turbidity progressively, indicating that re-association followed dissociation of casein micelles. Especially at 40 °C and at 250 and 300 MPa, the turbidity increased beyond untreated milk. Dynamic light scattering was used to investigate casein micelle sizes in milk immediately after long time (up to 4 h) pressurization at 250 and 300 MPa and casein micelle size distributions were bimodal with micelle sizes markedly smaller and markedly larger than those of untreated milk. Pressure modified casein micelles present after treatment of milk at 250 and 300 MPa were concluded to be highly unstable, since the larger micelles induced by pressure showed marked changes toward smaller particle sizes in milk left at ambient pressure.     

Effects of high pressure on some constituents and properties of buffalo milk

In this study, effects of high pressure (HP) on some constituents and properties of buffalo milk were examined. HP treatment at 100-600MPa for 30 min affected casein micelle size only slightly, whereas treatment at 800 MPa increased it by approximately 35%. Levels of non-micellar alpha(S1)and beta-caseins were increased by treatment > or = 250MPa, and were highest after treatment at 400-800MPa. The level of non-micellar calcium increased with increasing pressure up to 600 MPa. The L*-value of the milk decreased gradually with increasing pressure, from approximately 82 for untreated milk to approximately 65 for milk treated at 800 MPa. Milk pH was increased by approximately 0.07 units after treatment at 100-800 MPa, with no significant difference between treatment pressures. Denaturation of alpha-lactalbumin occurred at pressures > or = 400 MPa, and reached >90% after treatment at 800 MPa, whereas beta-lactoglobulin (beta-Ig) was denatured > 100 MPa, reaching approximately 100% after treatment at 400MPa; after treatment > or = 400MPa, all beta-Ig was associated with the casein micelles. The rennet coagulation time of buffalo milk increased with increasing pressure, whereas the strength of the coagulum formed decreased after treatment at 250-800 MPa. Overall, HP treatment affected many constituents and properties of buffalo milk; some of these effects have also been observed in the milk from other species, but the extent of the effects, and the pressure at which they occurred, differed considerably.     

High pressure treatment of bovine milk: effects on casein micelles and whey proteins

Effects of high pressure (HP) on average casein micelle size and denaturation of alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg) in raw skim bovine milk were studied over a range of conditions. Micelle size was not influenced by treatment at pressures <200 MPa, but treatment at 250 MPa increased micelle size by approximately 25%, while treatment at > or = 300 MPa irreversibly reduced it to approximately 50% of that in untreated milk. The increase in micelle size after treatment at 250 MPa was greater with increasing treatment time and temperature and milk pH. Treatment times > or = 2 min at 400 MPa resulted in similar levels of micelle disruption, but increasing milk pH to 7.0 partially stabilised micelles against HP-induced disruption. Denaturation of alpha-la did not occur < or = 400 MPa, whereas beta-lg was denatured at pressures >100 MPa. Denaturation of alpha-la and beta-lg increased with increasing pressure, treatment time and temperature and milk pH. The majority of denatured beta-lg was apparently associated with casein micelles. These effects of HP on casein micelles and whey proteins in milk may have significant implications for properties of products made from HP-treated milk.     

超高压结合温热处理对脱脂乳透光率和粒径及蛋白溶解性的影响

目的：研究高压结合温热（≤50 ℃）处理对脱脂乳粒径、透光率及蛋白溶解性的影响。方法：采用不同温度（常温、30、40、50 ℃）和压力（0.1～700 MPa）分别处理脱脂乳10～30 min,利用激光纳米粒度仪检测脱脂乳粒径变化,分光光度法检测透光率变化,考马斯亮蓝法测定可溶性蛋白质量浓度变化。结果表明,脱脂乳透光率在压力不高于100 MPa范围内不受温度、压力和处理时间的影响;在200～700 MPa范围内,常温条件下处理的脱脂乳透光率随压力的升高和处理时间的延长而增大,在700 MPa下处理20 min时透光率最大,增幅为1 011%;在30～50 ℃范围内,透光率随压力增大（200～700 MPa）呈现先升高后降低的趋势,在40 ℃、500 MPa下处理10 min时透光率增幅最大（537%）,透光率受温度和保压时间的影响,且超高压结合温热处理脱脂乳透光率均高于未处理脱脂乳。在常温、0.1～400 MPa范围内,脱脂乳的中位径（Dx(50)）随压力的增大而总体降低,在400～700 MPa范围内变化趋势平稳,但均小于未处理脱脂乳的Dx(50);30、40、50 ℃下,脱脂乳Dx(50)随压力增大呈现先升高后降低的趋势,分别在400～700、300～500、200～400 MPa范围内变化趋势平稳,且受时间影响较小。经高压处理的脱脂乳中可溶性乳蛋白（soluble protein,S-Pro）质量浓度总体呈增加趋势,且受压力、时间和温度的影响,在30 ℃、500 MPa下处理30 min,S-Pro质量浓度增幅最大（83.55%）。pH 4.6下可溶性蛋白（S-Pro-pH 4.6）质量浓度在压力不高于100 MPa时不受温度、压力和时间的影响;在200～700 MPa范围内,不同温度下,随压力升高和处理时间的延长,S-Pro-pH 4.6质量浓度呈现下降趋势。对各指标间相关性进行分析发现,透光率与Dx(50)间的相关性随温度升高减弱;透光率与S-Pro质量浓度呈正相关,与S-Pro-pH 4.6质量浓度呈负相关。S-Pro与S-Pro-pH 4.6之间呈负相关。结论：经超高压结合温热处理,能够引发脱脂乳透光率、粒径及蛋白溶解性的变化,且这些变化存在一定的相关性。     

High-pressure-induced interactions between milk fat globule membrane proteins and skim milk proteins in whole milk

The association of beta-lactoglobulin (beta-LG) and alpha-lactalbumin (alpha-LA) with milk fat globule membrane (MFGM), when whole milk was treated by high pressure in the range 100 to 800 MPa, was investigated using sodium dodecyl sulfate (SDS)-PAGE under reducing and nonreducing conditions. In SDS-PAGE under reducing conditions, beta-LG was observed in the MFGM material isolated from milk treated at 100 to 800 MPa for 30 min, and small amounts of alpha-LA and kappa-casein were also observed at pressures >600 MPa for 30 min. However, these proteins were not observed in SDS-PAGE under nonreducing conditions. These results indicate that beta-LG and alpha-LA associated with MFGM proteins via disulfide bonds during the high-pressure treatment of whole milk. The amount of beta-LG associated with the MFGM increased with an increase in pressure up to 800 MPa and with increasing time of pressure treatment. The maximum value for beta-LG association with the MFGM was approximately 0.75 mg/g of fat. Of the major original MFGM proteins, no change in butyrophilin was observed during the high-pressure treatment of whole milk, whereas xanthine oxidase was reduced to some extent beyond 400 MPa. In contrast to the behavior during heat treatment, PAS 6 and PAS 7 were stable during high-pressure treatment, and they remained associated with the MFGM.     

超高压处理对芒果泥品质的影响

为了提升芒果泥的品质,本研究采用了超高压、辐照和低温等离子三种非热加工手段对芒果泥进行处理,并对不同方法的杀菌效果进行分析比较。选取其中较优的方法（超高压）,进一步研究其对芒果泥的色度、感官、可溶性固形物含量以及储藏稳定性的影响。结果表明,超高压（≥200 MPa）和辐照（≥3 kGy）处理均对芒果泥有良好的杀菌效果,果泥的菌落总数均≤2 lg(CFU/g),达到商业无菌标准。但低温等离子处理效果不理想,当处理时间≤6 min时,果泥中的菌落总数均未达到商业无菌标准。超高压处理后芒果泥的口感与对照样品较为接近。大于500 MPa的压力处理后,芒果泥的储存期稳定性较好,特别是用600 MPa处理后的样品,其储存期至少可以达到9个月。这一结果表明,超高压可以在杀灭芒果泥中有害微生物提高芒果泥稳定性的同时,最大限度地保持芒果泥的原有品质。本研究为超高压技术在食品加工中的应用提供了一定的理论依据和方法指导。     

超高压射流灭菌对牛奶理化特性的影响

利用超高压射流对撞式/碰撞式技术处理液态奶,考察其相对密度、滴定酸度、pH值、灰分碱度、浊度、颗粒粒径等理化性质。结果表明,超高压射流处理后,液态奶的灰分碱度及压力≥200 MPa时滴定酸度均符合灭菌乳国家标准(GB5408.2-1999);相对密度保持不变;浊度呈上升趋势;对撞方式均质效果明显优于碰撞方式。超高压射流处理牛奶的最佳工艺为200 MPa对撞方式处理。该研究为超高压射流杀菌奶的后续深入研究奠定了基础。