矢车菊-3-O-葡萄糖苷及其代谢物原儿茶酸对杂环胺诱导细胞损伤的修复机制

目的：研究矢车菊-3-O-葡萄糖苷（cyanidin-3-O-glucoside,C3G）及其主要代谢物原儿茶酸（protocatechuic acid,PCA）对杂环胺诱导细胞损伤的修复机制。方法：分别采用2-氨基-3-甲基咪唑并[4,5-f]喹啉（2-amino-3-methylimidazo[4,5-f]quinoline,IQ）和2-氨基-1-甲基-6-苯基-咪唑[4,5-b]吡啶（2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine,PhIP）诱导HepG2细胞损伤,利用细胞毒性实验（cell counting kit-8,CCK-8）、Hoechst33258染色法、流式细胞术和实时荧光定量聚合酶链式反应（quantitative polymerase chain reaction,qPCR）技术,评价C3G和PCA对杂环胺诱导损伤细胞的存活情况、细胞周期以及凋亡和DNA损伤关键基因表达的影响。结果：C3G和PCA能够显著提高杂环胺损伤细胞的存活率（P<0.05）,并使细胞发生S期阻滞。与IQ单独损伤组相比,C3G和PCA均可...     

三种粗粮粉体外调节肠道菌群的作用研究

通过在体外模拟构建消化和发酵体系,研究不同来源的三种麸皮(小麦麸皮、黑小麦麸皮和燕麦麸皮)配制成的粗粮粉对肠道菌群调节作用的影响。采用高通量测序技术16S rRNA对肠道菌群的多样性和组成进行分析,结果表明,粗粮粉发酵后微生物多样性降低,肠道菌群组成发生了较大变化,拟杆菌门比例下降,厚壁菌门比例升高,代谢产生的短链脂肪酸含量显著增多(p<0.05);其中,燕麦粗粮粉促进双歧杆菌体外增殖的效果优于其他两组粗粮粉,分别是小麦粗粮粉和黑小麦粗粮粉的1.45和2.14倍。本研究为调制加工性能好、保健价值高的粗粮粉配方提供了理论依据。     

大豆低聚肽对自发性高血压大鼠血压及血浆血管紧张素的影响

目的：探究大豆低聚肽对于大鼠血压及血浆血管紧张素的影响。方法：采用酶法制备大豆低聚肽,随后进行体外血管紧张素I转换酶（angiotensin I converting enzyme,ACE）活性抑制实验及体内实验,实验设正常对照组（正常血压大鼠（WKY大鼠）饲喂高剂量大豆低聚肽）、阴性对照组（自发性高血压大鼠（SHR大鼠））、阳性对照组（SHR大鼠饲喂卡托普利）和低、中、高剂量组（SHR大鼠饲喂0.90、1.80、4.50 g/kg大豆低聚肽）,喂养30 d后,观察大鼠血压、心率、尿蛋白质量、血管紧张素II质量浓度等指标的变化。结果：大豆蛋白最佳酶解条件为：碱性蛋白酶和中性蛋白酶质量分数各0.1%、50 ℃酶解4 h,此条件下10 mg/mL大豆低聚肽ACE活性抑制率达到71.2%。经饲喂不同剂量大豆低聚肽30 d后,WKY大鼠血压变化不显著（P＞0.05）,SHR大鼠血压有下降趋势;饲喂高剂量大豆低聚肽在第4周时可以显著降低SHR大鼠血压和血管紧张素II质量浓度（P＜0.05）,但对于大鼠心率和尿蛋白质量无显著影响（P＞0.05）。结论：体外实验证明,与大豆蛋白相比,大豆低聚肽对于ACE活性的抑制效果更好;体内实验证明大豆低聚肽可以降低SHR大鼠的血压和血管紧张素II质量浓度,且对正常大鼠血压无明显影响,推测大豆低聚肽通过抑制ACE活性的方式发挥降压功效。     

基于不同乳糖浓度的乳蛋白浓缩物发酵特性研究

利用保加利亚乳杆菌和嗜热链球菌复合发酵剂对乳蛋白浓缩物(milk protein concentrate,MPC)进行发酵,研究了不同乳糖浓度下MPC的发酵特性。结果表明,乳糖浓度影响MPC发酵进入稳定期的时间与pH值,随着乳糖浓度的升高,MPC发酵物的最终pH值下降(pH值范围4.14～4.59);微流变学研究表明,随乳糖浓度升高,MPC发酵物的宏观黏性因子减小,而固液平衡值和流动性指数增大;质构特性研究表明,MPC发酵物的持水力随乳糖浓度升高而逐渐升高,胶着性、弹性则呈现先增大后减小的趋势,而硬度、黏力不受影响;气相色谱-质谱联用分析结果显示,酸类化合物和酮类化合物是MPC发酵物中的主要挥发性物质,随乳糖浓度的增加,酸类化合物含量减少,而2,3-丁二酮、3-羟基-2-丁酮等乳糖代谢物的含量增加。本研究结果旨在为进一步了解MPC的发酵特性并拓宽MPC在不同发酵乳制品中的应用提供基础数据。     

Innovative multilayer antimicrobial films made with Nisaplin® or nisin and cellulosic ethers: Physico-chemical characterization,bioactivity and nisin desorption kinetics

In this study, ethylcellulose/hydroxypropylmethylcellulose/ethylcellulose (EC/HPMC/EC) three-layer films including Nisaplin® or nisin and lecithins were formulated. Lecithins were used as plasticizers to ensure cohesion between hydrophobic ethylcellulose and hydrophilic HPMC layers. It was observed that the introduction of pure nisin or its non-pure commercial form Nisaplin® into films didn't significantly alter their mechanical and optical properties. Additionally, these nisin or Nisaplin-loaded multilayer films showed significant antimicrobial activity. The comparison of inhibition diameters obtained with EC/HPMC film used as control and EC/HPMC/EC films demonstrated that the three-layer films delayed nisin desorption. This was confirmed by the kinetics of nisin release in a (0.8% w/v) NaCl solution at 28 °C: nisin from two-layer EC/HPMC films totally desorbed within 0.5 h, while the three-layer films allowed to expand nisin release time over 20 h. The ratio of nisin desorption coefficients (k_d): k_{d (EC/HPMC)}/k_{d (EC/HPMC/EC)} was determined after desorption modelling, and was found to be up to 118, proving that multilayer films with hydrophobic layers could be a potential way to control nisin release from antimicrobial bio-packagings.Industrial relevanceThis paper concerns active packaging, considered as a new approach to preserve food shelf life. Active packaging is a real gain for plastic and food industrials. Coating was used to obtain antimicrobial packaging. The impact of incorporating the antimicrobial agent in multilayer films on the release kinetics is investigated.     

不同分子特性玉米蛋白高F值活性肽的制备及其模拟消化吸收

以玉米黄粉为原料,通过碱性蛋白酶和风味蛋白酶复合酶解制备玉米蛋白高F值活性肽(High Fischer ratio peptide,HFRP),同时根据分子量、电荷性和疏水性差异将HFRP进行分离纯化,并对其吸收特性和耐胃肠消化特性进行探究。结果表明:通过复合酶解法对玉米黄粉进行水解,得到HFRP(F值=26.29)。将HFRP分别按照分子量、电荷性和疏水性进行分离、收集,得到12种组分。通过构建Caco-2细胞体外吸收模型,研究不同分子特性组分的吸收状况,采用质谱扫描鉴定出质荷比(m/z)分别为203.1409、229.2980、226.9517、284.2966的高吸收短肽LA、IP、PL、HQ;通过研究不同分子特性组分的胃肠消化状况,采用质谱扫描鉴定出质荷比(m/z)分别为226.9517、284.2966的耐消化短肽PL和HQ。短肽PL和HQ分子量小,疏水性高,在溶液中带有正电荷,具有优先吸收和耐胃肠消化的特点。本研究为玉米蛋白高F值活性肽的开发提供了理论依据。     

冷破、热破番茄酱的香气特征及其与非挥发性组分之间的关系

番茄酱是一种重要的调味品,因其独特的口感和风味而广受消费者喜爱。本文以通过冷破（cold break,CB）、热破（hot break,HB）生产的8种番茄酱作为研究对象,采用顶空固相微萃取-气相色谱-质谱联用（headspace solid-phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）技术对其挥发性风味化合物的组成及相对含量进行分析,计算香气活度值（odor activity value,OAV）确定特征风味化合物,结合主成分分析（principal component analysis,PCA）以及相关性分析确定番茄酱中的香气成分与还原糖、有机酸、抗坏血酸以及果胶含量之间的关系。结果表明：不同破碎方法的番茄酱中挥发性风味化合物的组成及相对含量存在明显差别,8个样品中共鉴定出61种挥发性风味化合物,以醛类、醇类和酮类为主,其中22种为OAV≥1的香气活性化合物;CB番茄酱中的挥发性风味化合物组成及相对含量要显著（P<0.05）高于HB番茄酱,并且CB处理有利于保持番茄酱中较高的...     

Biopolymer nanoparticles as potential delivery systems for anthocyanins: Fabrication and properties

Biopolymer nanoparticles and microparticles may be used as delivery systems for bioactive compounds in food and pharmaceutical applications. In this study, biopolymer nanoparticles were assembled from whey protein isolate (WPI) and beet pectin (BP) using thermal processing and electrostatic complexation. This approach involved mixing the two biopolymers at pH 5.8, heating (90 °C, 5 min) to induce protein nanoparticle formation and then adjusting the solution to pH 4.0 to promote coating of the protein nanoparticles with pectin. This process led to the formation of relatively small anionic biopolymer nanoparticles (d < 200 nm) at pH 4. The biopolymer particles had a high negative charged from pH 8 to 4.0 but became less anionic at lower pH values. The mean particle diameter was relatively small (d < 200 nm) around pH 4.0 but increased appreciably at lower and higher pH due to particle flocculation. The biopolymer nanoparticles were loaded with an anthocyanin-rich extract. A higher loading efficiency was observed when anthocyanin was added before heating the WPI-BP solution (LE = 55%) rather than after (LE = 35%), which was attributed to increased protein–polyphenol interactions. The encapsulation of anthocyanins within biopolymer particles improved their heat stability. However, encapsulated anthocyanin had a lower antioxidant activity than non-encapsulated anthocyanin, which was attributed to the thermal processing step required during particle fabrication and the binding of anthocyanins to biopolymers within the nanoparticles. Color measurements indicated that the encapsulation of anthocyanin within biopolymer particles did not inhibit its degradation after ascorbic acid addition. Overall, our results show that the encapsulation of anthocyanins within the biopolymer particles fabricated in this study was not particularly effective at improving their antioxidant activity or color stability. Alternative strategies are therefore needed to encapsulate this important color and nutraceutical agent.