辛烯基琥珀酸纳米淀粉酯颗粒的制备及其食品级Pickering乳液的特性

利用醇沉法结合辛烯基琥珀酸酐酯化反应,成功制备能够稳定食品级Pickering乳液的纳米淀粉酯颗粒。以纳米淀粉酯粒径、Zeta电位、光学和荧光显微镜观察为指标,研究颗粒添加量、pH值和离子强度对Pickering乳液稳定性的影响。结果表明,体系pH值和离子强度在一定范围内改变了纳米淀粉酯的电位值,其中在极端pH值或者高离子强度条件下,纳米淀粉酯的电位绝对值最低。研究发现,当纳米淀粉酯添加量为2.0 g/100 mL时,制备的Pickering乳液具有较强的稳定性;此外,在体系pH 6.0并且KCl浓度为0.005 mol/L条件下,Pickering乳液分散相油滴的直径最小并且分布均匀,油滴不容易发生聚结,Pickering乳液的稳定性最高。     

大豆脑磷脂对汉麻分离蛋白Pickering乳液的形成及其性质的影响

为研究大豆脑磷脂对汉麻分离蛋白Pickering乳液性质的影响,本文通过改变大豆脑磷脂添加量考察不同大豆脑磷脂添加量（10%、20%、30%、40%）对汉麻分离蛋白Pickering乳液乳化活性指数、微观结构、乳滴粒径、Zeta电位、流变学特性及贮藏稳定性的影响,初步探究大豆脑磷脂的添加对汉麻分离蛋白Pickering乳液稳定机制的影响。结果表明:在汉麻分离蛋白Pickering乳液体系中加入大豆脑磷脂后,其乳液稳定性有所提高;在大豆脑磷脂添加量为30%时,得到的Pickering乳液各项指标最佳,乳液的乳化活性指数为4.63 m2?g,乳液的分散指数为0.23;乳滴粒径为125 nm,Zeta电位值为?27.12 mV;乳液的表观黏度较小且无明显乳液聚结现象发生,并在贮藏7 d后未出现油析现象,乳液稳定性好。该研究为汉麻分离蛋白Pickering乳液稳定性提高及大豆脑磷脂的应用领域拓宽提供了理论基础。     

不同大分子乳化剂构建番茄红素纳米乳液的体外消化规律比较

通过体外模拟消化,研究以辛烯基琥珀酸酯化（octenyl succinic anhydride,OSA）变性淀粉、乳清分离蛋白（whey protein isolate,WPI）、酪蛋白酸钠（sodium caseinate,SC）为乳化剂构建的番茄红素纳米乳液的消化规律。结果表明,消化过程中纳米乳液的液滴大小、Zeta电位和微观结构取决于乳化剂类型,OSA变性淀粉和蛋白质类乳化剂构建的纳米乳液分别在肠和胃阶段发生水解,液滴聚集,乳液平均粒径增大,同时Zeta电位绝对值达到最小。经胃肠消化后3 种乳化剂构建的番茄红素纳米乳液游离脂肪酸释放率的大小排序为OSA变性淀粉（92.25%）＞SC（86.53%）＞WPI（79.88%）,高于对照组的48.7%,表明纳米乳液包埋体系能有效改善番茄红素的消化特性,且以OSA变性淀粉构建的纳米乳液表现出比蛋白质类乳化剂更高的番茄红素生物利用率,达到（25.60±3.08）%。     

芋头淀粉及其稳定化Pickering乳液的性质表征

为了探究芋头淀粉能否稳定Pickering乳液,通过粒径分析、接触角测定、Zeta电位测定等方法表征芋头淀粉的理化性质,然后以液体石蜡为油相,芋头淀粉为单一乳化剂,考察其乳液的理化性质,同时与粳米、玉米、小麦和山药淀粉进行比较。结果表明:芋头淀粉的平均粒径最小（2.29 μm）,颗粒呈不规则形状和多边形态;摩尔质量最小且分布均匀;持油、持水率最高,分别为158.33%、136.24%;三相接触角为36.60°,Zeta电位为-25.63 mV。在芋头淀粉水分散液质量浓度20 mg/mL、油相分数50%、分散强度10000 r/min和分散4 min条件下制备的Pickering乳液能在30 d内保持稳定,且储藏过程测量到的乳滴粒径最小（34.64~52.20 μm）,其乳液的流变学测定显示形成了较弱的乳液网络结构。综上,芋头淀粉可以有效稳定Pickering乳液,有望进一步开发作为稳定剂或乳化剂应用到食品中。     

大豆分离蛋白-花青素共价复合物制备纳米颗粒及其Pickering乳液特性分析

构建大豆分离蛋白-花青素共价复合纳米颗粒,以粒径、Zeta电位、自由基清除能力、光学显微镜观察为指标,对纳米颗粒和Pickering乳液进行研究。结果表明,通过添加花青素在一定程度上改变了纳米颗粒和Pickering乳液的粒径分布与Zeta电位值;对比可知,添加花青素后纳米颗粒和乳液体系更加稳定。此外,当花青素添加量为0.15%时,纳米颗粒的粒径分布较为均一,粒径相对体积最大;纳米颗粒Zeta电位绝对值最大;自由基清除能力相对较强;并且以0.15%花青素添加量的纳米颗粒制备的Pickering乳液液滴分布较为均匀,不易发生聚集,较为稳定。     

阿魏酸藜麦淀粉酯Pickering乳液的制备及其抗氧化特性

为了研究阿魏酸藜麦淀粉酯对Pickering乳液的结构和抗氧化特性的影响,实验以藜麦淀粉为原料,采用双酯化法对藜麦淀粉进行改性处理,对比分析阿魏酸接枝前后及不同取代度淀粉酯的结构和性质,并对其稳定Pickering乳液的稳定性、粒径、Zeta电位、抗氧化性及液滴微观结构变化等进行研究。结果显示:藜麦淀粉颗粒经辛烯基琥珀酸酐和阿魏酸双酯化改性后,随着阿魏酸取代度的增加,乳液液滴的粒径随之增大,Zeta电位下降,抗氧化特性显著(P<0.05)增强。通过激光共聚焦显微镜、扫描电镜与光学显微镜观察发现,乳液液滴呈圆球形且分布均匀。当阿魏酸取代度为0.69%时,ABTS+自由基清除率达到70.77%,与未接枝阿魏酸的乳液相比,ABTS+自由基清除率增加65.40%,乳液的抗氧化能力明显提高。     

木薯纳米淀粉的制备及乳化性能研究

以木薯淀粉为原料,采用沉淀法制备木薯纳米淀粉,探究淀粉添加量、超声波振幅、乙醇体积分数、搅拌时间对纳米淀粉粒径的影响,同时分析了木薯纳米淀粉的基本特质和乳化性能。结果表明,淀粉添加量5%(质量分数)、超声波振幅70%、乙醇体积分数60%、搅拌时间15 min时,粒径最小为75.91 nm。核磁共振氢谱、扫描电镜、透射电镜分析表明,沉淀法成功制备木薯纳米淀粉,淀粉基本化学结构不变;与原淀粉相比,用纳米淀粉为乳化剂制备的Pickering乳液粒径较小,乳化活性、乳化稳定性及贮藏稳定性均得到显著提升。该研究结果可为木薯淀粉应用提供参考依据。     

大豆分离蛋白-卡拉胶-黄原胶三元复合Pickering乳液的制备与特性分析

本研究制备大豆分离蛋白（Soybean protein isolate,SPI）-卡拉胶-黄原胶三元复合Pickering乳液，考察不同SPI与卡拉胶-黄原胶配比、乳液pH、卡拉胶质量浓度、黄原胶质量浓度以及大豆油内相体积对三元Pickering乳液体系的粒径、Zeta电位、乳化活性指数（Emulsifying activity index,EAI）、乳化稳定性（Emulsifying stability index,ESI）和SPI二级结构的影响，并研究常温贮藏条件下不同内相体积乳液体系的特性变化。结果表明：当SPI与复合多糖的质量浓度比为1:10,pH为9.0，卡拉胶和黄原胶质量浓度均为0.2%，油相体积为10%～85%时，SPI-卡拉胶-黄原胶三元复合Pickering乳液的稳定性均较好，平均粒径达351±24.12 nm,Zeta电位绝对值达99.4±1.4 mV。随着大豆油内相体积从10%增大至85%,Pickering乳液颗粒的粒径分布更加均一、稳定，当油相体积分数为75%时，乳液颗粒分散状态最佳，EAI和ESI达到最大值，SPI α-螺旋和β-折叠含量最高。常温贮藏实验表...     

复合改性小米淀粉Pickering乳液负载β-胡萝卜素性能研究

该文以复合改性小米淀粉稳定的Pickering乳液负载β-胡萝卜素,研究了功能性Pickering乳液的pH稳定性、盐离子稳定性、贮存稳定性,通过透析实验、贮存实验、模拟人体胃肠消化实验,研究功能活性物质在复杂环境中的荷载特性和释药特性。结果表明,负载β-胡萝卜素的复合改性小米淀粉Pickering乳液具有良好的pH稳定性、盐离子稳定性和贮存稳定性;β-胡萝卜素在复合改性小米淀粉Pickering乳液的初始负载率为92.92%,相较单一改性辛烯基琥珀酸淀粉(82.44%)显著提高;光照、高温等不良条件会引起负载率下降,15 d后复合改性小米淀粉Pickering乳液中β-胡萝卜素负载率依次为71.71%(4℃避光)>62.60%(25℃避光)>58.25%(25℃光照)>51.97%(37℃避光)。透析释放和模拟体外胃肠消化实验结果表明,复合改性小米淀粉稳定的Pickering乳液对β-胡萝卜素有较强的保护作用,有效降低了β-胡萝卜素释放速率,提升了β-胡萝卜素保留率。     

茶黄素-壳聚糖纳米乳液的制备及其性能分析

纳米乳液系统解决了生物活性分子在运输、传递过程中不稳定、易氧化,聚合或缩合、生物利用率低等问题.本试验利用壳聚糖包埋茶黄素制备纳米乳液,再通过体外模拟消化,对乳液进行乳滴粒径、Zeta电位和微观结构检测,探究其在各消化阶段的水解程度.结果表明,原始乳滴对茶黄素的包埋率为80.04％;在唾液消化中,液滴粒径、Zeta电位...     

Ferrous bisglycinate content and release in W1/O/W2 multiple emulsions stabilized by protein–polysaccharide complexes

Ferrous bisglycinate aqueous solution was entrapped in the inner phase (W₁) of water-in-oil-in-water (W₁/O/W₂) multiple emulsions. The primary ferrous bisglycinate aqueous solution-in-mineral oil (W₁/O) emulsion contained 15% (w/w) ferrous bisglycinate, had a dispersed phase mass fraction of 0.5, and was stabilized with a mixture of Grindsted PGPR 90:Panodan SDK (6:4 ratio) with a total emulsifiers concentration of 5% (w/w). This primary emulsion was re-emulsified in order to prepare W₁/O/W₂ multiple emulsions, with a dispersed mass fraction of 0.2, and stabilized using protein (whey protein concentrate (WPC)):polysaccharide (gum arabic (GA) or mesquite gum (MG) or low methoxyl pectin (LMP)) complexes (2:1 ratio) in the W₂ aqueous phase. The W₁/O/W₂ multiple emulsion stabilized with WPC:MG (5% w/w total biopolymers concentration) provided smaller droplet sizes (2.05 μm), lower rate of droplet coalescence (7.09 × 10⁻⁷ s⁻¹), better protection against ferrous bisglycinate oxidation (29.75% Fe³⁺) and slower rate of ferrous bisglycinate release from W₁ to W₂ (K_H = 0.69 mg mL⁻¹ min^−0.5 in the first 24 h and 0.07 mg mL⁻¹ min^−0.5 for the next 19 days of storage time). Better encapsulation efficiencies, enhanced protection against oxidation and slower release rates of ferrous bisglycinate were achieved as the molecular weight of the polysaccharide making up protein:polysaccharide complex was higher. Thus, the factor that probably affected most the overall functionality of multiple emulsions was the thickness of the complex adsorbed around the multiple emulsion oil droplets. These thicknesses determined indirectly by measuring the z-average diameter of the complexes, and that of the WPC:MG (529.4 nm) was the largest.     

Structural and textural characteristics of reduced-fat cheese-like products made from W1/O/W2 emulsions and skim milk

The chemical composition, yield, structural arrangement, instrumental textural characteristics, and preference sensory evaluation of reduced-fat cheese-like products manufactured from skim milk and different water-in-oil-in-water (W₁/O/W₂) emulsions were determined. A full-fat white fresh cheese (WFC) was prepared from milk containing 27 g of milk-fat L⁻¹, and five reduced-fat white fresh cheese-like products (EC) were made from skim milk added with 25 g of multiple emulsions L⁻¹ containing canola oil and stabilized/emulsified by amidated low-methoxyl pectin (LMP), carboxymethylcellulose (CMC), gum Arabic (GA), and blends of GA-CMC or GA-LMP. The chemical composition, yield, structural arrangement and texture of the cheese-like products were affected by the biopolymers used as emulsifying/stabilizing agents of the multiple emulsions. CMC produced an EC with similar textural behaviour than the WFC cheese. GA contributed to a higher yield and fat content in the EC cheese in comparison with CMC and LMP cheese. GA and LMP contributed to increased values of hardness and chewiness of the EC cheese. The cheese made with multiple emulsions incorporating GA and LMP emulated best the textural characteristics of the WFC cheese. All of the EC cheese showed marked differences in microstructure.     

固体酸SiO_2-Ti(SO_4)_2-Zr(SO_4)_2催化麻疯树籽油醇解反应的研究

通过溶胶-凝胶法制备了Si O2载体,所得载体再通过浸渍法制备得到负载Ti(SO4)2和Zr(SO4)2的复合型固体酸催化剂Si O2-Ti(SO4)2-Zr(SO4)2,利用热重分析(TG-DTG)和傅里叶红外光谱(FTIR)对催化剂的特性进行初步表征。此外,以转化率为指标,研究了复合型固体酸催化剂在麻疯树籽油醇解反应中的催化活性,并考察催化剂用量、醇油摩尔比、反应温度和反应时间对醇解反应的影响。TG-DTG分析结果表明,催化剂的焙烧温度应选择300℃,此条件下可以制备催化活性较好的催化剂;FTIR表征结果表明,浸渍Ti(SO4)2和Zr(SO4)2后,该活性物质成功负载到Si O2载体表面。单因素实验结果表明最佳反应条件为:反应温度120℃,催化剂用量5%,醇油摩尔比15∶1,反应时间5 h;在此条件下,麻疯树籽油的转化率最高可达92.53%。     

含水量对新疆鲜食核桃贮藏期黄曲霉生长及黄曲霉毒素M1积累的影响

目的:提高新疆鲜食核桃的贮藏安全性。方法:以新疆“新2”薄皮核桃为材料，无菌水接种为对照组，黄曲霉菌接种为试验组，将从自然霉变核桃上分离纯化出的黄曲霉菌人工接种至不同含水量(10%,15%,20%,25%,30%)的新疆薄皮鲜食核桃上，探究黄曲霉菌生长量及产毒变化情况。结果:最适宜黄曲霉菌生长繁殖并分泌黄曲霉毒素M₁的核桃含水量为15%;随着核桃含水量的升高，黄曲霉菌生长量呈先上升后下降趋势，但各含水量之间的生长量各不相同，且黄曲霉菌生长量与产生黄曲霉毒素M₁的量成正比。结论:原料的含水量与黄曲霉菌生长量及产生黄曲霉毒素M₁的量有着密切的关系。     

Zur Untersuchung von Milch und Milchprodukten auf die Aflatoxine B1, B2, G1, G2 und M1

Zusammenfassung Der vom Bundesgesundheitsamt vorgelegte Entwurf zur Bestimmung der Aflatoxine B₁, B₂, G₁ und G₂ wurde auf die zusätzliche Erfassung des Aflatoxins M₁ überpruft. Es wurde Wert darauf gelegt, die ursprüngliche Methode nur wenig zu ändern, um die zahlreichen Vorschläge zur Aflatoxin-Analytik nicht noch weiter zu vermehren. Mit verhältnisäßig geringen Änderungen können alle Aflatoxine, also B₁, B₂, G₁, G₂ and M₁ in flüissiger Milch, Milchpulver, Butter, Käse, Quark, Saline, Joghurt und Fruchtjoghurt quantitativ erfaßt werden.

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Investigations of aflatoxin B₁, B₂, G₁, G₂, and M₁ in milk and milk products

Summary The method proposed by the Federal Department of Health for the determination of aflatoxin B₁, B₂, G₁, and G₂ was tested for additional determination of aflatoxin M₁. With relatively small changes of the original method, all aflatoxins including. B₁, B₂, G₁, G₂, and M₁ can be determined quantitatively in milk, milk powder, butter, cheese, quark, cream, yoghurt and fruit yoghurt.

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37. Mitteilung: Zur Aflatoxinbildung in Milch und Milchprodukten.     

Zur Untersuchung von Milch und Milchprodukten auf die Aflatoxine B1, B2, G1, G2 und M1

Der vom Bundesgesundheitsamt vorgelegte Entwurf zur Bestimmung der Aflatoxine B₁, B₂, G₁ und G₂ wurde auf die zusätzliche Erfassung des Aflatoxins M₁ überpruft. Es wurde Wert darauf gelegt, die ursprüngliche Methode nur wenig zu ändern, um die zahlreichen Vorschläge zur Aflatoxin-Analytik nicht noch weiter zu vermehren. Mit verhältnisäßig geringen Änderungen können alle Aflatoxine, also B₁, B₂, G₁, G₂ and M₁ in flüissiger Milch, Milchpulver, Butter, Käse, Quark, Saline, Joghurt und Fruchtjoghurt quantitativ erfaßt werden.     

Theasaponin E1 destroys the salt tolerance of yeasts

Cells of Zygosaccharomyces rouxii in a medium containing a high concentration of NaCl were killed during incubation for 2–4 h with a low concentration of a mixture of saponins from tea seeds (TSS). The higher the concentration of NaCl in the medium, the higher the inhibitory effect of TSS on the growth of the yeast. The above inhibitory effect of TSS on the growth of the yeast was not observed when cells were incubated in hypertonic media composed of nonionic substances such as sugars. The ATPase activity of plasma membrane preparations from the yeast cells was slightly affected by the addition of TSS. It is shown that TSS facilitates leakage of glycerol from the yeast cells under NaCl-hypertonic conditions. The major inhibitor in the mixture of saponins was isolated and identified as theasaponin E₁. Its isomer, theasaponin E₂, did not have any effect on the salt tolerance of Z. rouxii or Saccharomyces cerevisiae.     

纳米Ag@TiO2、Fe@TiO2和Zn@TiO2的抑菌活性比较研究

探索常见金属离子掺杂对抑菌片的抑菌性能的影响,为新型纳米TiO₂抑菌片的制备与改善提供技术基础。选择固定质量分数的Ag⁺、Zn²⁺和Fe³⁺掺杂TiO₂,通过抑菌圈、MIC与MBC方法综合评价其抑菌性能,对微观结构进行表征分析,探讨抑菌性能差异的原因。结果表明:抑菌性能大小顺序为Ag@TiO₂> Zn@TiO₂> Fe@TiO₂,Zn@TiO2 的抑菌活性较好但抑菌稳定性差Ag@TiO2对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是10、20 mg/L,Zn@TiO₂对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是30、50 mg/L。表征发现抑菌活性强弱主要归因于纳米TiO₂表面与金属离子共同产生的活性位点数量及稳定性,与孔结构或表面宫能团的关联不大。     

免疫亲和层析净化-高效液相色谱法同时测定牛奶和奶粉中黄曲霉毒素B1、B2、G1、G2、M1、M2

建立牛奶和奶粉中黄曲霉毒素B1、B2、G1、G2、M1、M2的免疫亲和层析净化和柱后衍生高效液相色谱测定方法。样品经溶解、离心、过滤后,通过免疫亲和柱,黄曲霉毒素特异性抗体选择性地与存在的黄曲霉毒素抗原键合,形成抗体-抗原复合体。甲醇-乙腈混合溶液(4:5,v:v)洗脱,带荧光检测器的高效液相色谱仪经柱后衍生测定,外标法定量。标准曲线线性良好,添加回收率在57.0%～88.7%,相对标准偏差在3.37%～16.9%,牛奶中各黄曲霉毒素检出限:B1为2ng/kg,B2为1ng/kg,G1、G2为3ng/kg,M1、M2为5ng/kg;奶粉中B1为20ng/kg,B2为10ng/kg,G1、G2为30ng/kg,M1、M2为50ng/kg,检测低限能够满足各国对牛奶和奶粉中黄曲霉毒素的限量要求。该方法准确、快速、灵敏度高,适用于牛奶和奶粉中黄曲霉毒素的测定。     

Storage of green coffee in hermetic packaging injected with CO2

The objective of this study was to evaluate the physical, chemical, and sensory qualities of green coffee beans (Coffea arabica L.) during storage in different types of packaging. Coffee was stored from October 2008 to September 2009 in a warehouse of the Agriculture Society Ltda. (SAAG) in Santana da Vargem, southern Minas Gerais State, Brazil. The treatments in the factorial design consisted of two types of packaging (hermetic big bags with the injection of up to 60% CO₂ in a controlled atmosphere; similar bags but without the injection of CO₂ in a modified atmosphere) and three sampling positions in the bags (high, medium, and low). At 3-month intervals during a 12-month period, grains were analyzed to determine their water content, color, electrical conductivity, potassium lixiviation, and content of sugars. Sensory analysis was also conducted at these sampling times. The storage of green coffee beans in hermetic big bags on a commercial scale under modified and controlled atmospheric conditions is viable over a 12-month period. The coffee packed in big bags maintained its quality and exhibited an intensification of the green coloration of the grains during storage. Sensory analysis of coffee beans stored in a controlled atmosphere showed that the medium sampling position yielded the best ratings. The results of this analysis demonstrated that this storage technique can potentially increase the effectiveness of methods used to preserve the sensory quality of coffee beans.