模拟失重条件下水苏糖对大鼠肠道双歧杆菌的影响

研究水苏糖对模拟失重条件下大鼠肠道双歧杆菌的影响。SD大鼠随机分为地面对照组(FC组,饲喂基础饲料)、地面处理组(FTK组,饲喂添加水苏糖的饲料)、尾吊对照组(SC组,饲喂基础饲料)、尾吊处理组(STK组,饲喂添加水苏糖的饲料),试验28 d。采用选择性培养基测定不同时间节点大鼠粪便中双歧杆菌数量。结果表明:与FC组比较, SC组双歧杆菌数量显著减少(P<0.05或P<0.01), FTK组双歧杆菌数量显著增加(P<0.05);与SC组比较,STK组双歧杆菌数量显著增加(P<0.05)。模拟失重导致双歧杆菌生长受到抑制,水苏糖可促进双歧杆菌的增殖,能在一定程度上减轻模拟失重导致的大鼠肠道微生态失调。     

原花青素对模拟失重条件下大鼠体内铁过载的影响

研究了在模拟失重的条件下原花青素对大鼠体内过量铁的影响。通过对大鼠进行尾部悬吊使后肢去负荷,身体倾斜-30°建立模拟失重模型,大鼠能自由取食取水。通过对大鼠进行右旋糖酐铁腹腔注射建立铁过载模型(每两天一剂100 mg/(kg·体重),共5剂),对照组注射等体积的生理盐水。通过灌胃原花青素给予大鼠原花青素处理(40 mg/(d·(kg·体重)-1),原花青素溶解于饮用水中。通过检测大鼠体重、血红蛋白、血清铁蛋白判定模型建立是否成功,通过检测大鼠体重、血红蛋白、红细胞和血清铁蛋白、肝脏切片、股骨等指标综合评价原花青素对模拟失重条件下铁过载大鼠的影响。结果表明,原花青素处理未能够缓解模拟失重条件下过量铁造成的大鼠体重增长幅度的下降、血红蛋白和血清铁蛋白的增加、肝脏内铁的沉积、骨体积分数的降低以及血清铁调素含量的变化。铁过载和模拟失重对大鼠的健康有危害作用,并且在部分器官上表现为协同作用。原花青素并未缓解模拟失重条件下大鼠体内铁过载产生的不良影响。     

滁菊总黄酮对糖尿病大鼠血液流变学的影响

目的:观察滁菊总黄酮对糖尿病大鼠血液流变学的影响。方法:采用尾静脉注射链脲佐菌素(STZ)的方法建立糖尿病大鼠模型,观察滁菊总黄酮对糖尿病大鼠凝血时间,体外血栓长度及干、湿重,全血和血浆粘度,红细胞压积和红细胞沉降速率,以及血清一氧化氮(NO)含量的影响。结果:滁菊总黄酮能显著延长糖尿病大鼠凝血时间,降低体外血栓长度和干、湿重,降低红细胞压积,减慢红细胞沉降速率,升高血清NO含量。结论:滁菊总黄酮能够改善糖尿病大鼠血液流变学异常。      

模拟失重条件下复合活菌制剂对肠道双歧杆菌的影响

本研究采用-6°头低位卧床方法,模拟失重效应,通过观察和比较30 d卧床期间不同时间节点,受试者便样中双歧杆菌含量的变化,探讨食用复合活菌制剂对模拟失重条件下肠道中双歧杆菌数量降低的拮抗效果,为制定航天员肠道菌群失调调节方案提供技术支持。14名健康男性受试者,随机分为对照组、食用活菌制剂组,每组7人。对照组仅-6°头低位卧床,在30 d卧床期间第15天开始食用安慰剂,食用活菌制剂组于30 d卧床期间第15天开始每日口服活菌制剂。实验期间定期采集便样测定双歧杆菌数目。实验表明,对照组及食用活菌制剂组在卧床初期便样中双歧杆菌数量均显著降低(p0.05);卧床期间,食用复合活菌制剂组与对照组相比,双歧杆菌水平差异显著(p0.05)。30 d头低位卧床可引起双歧杆菌数量显著下降,这提示模拟失重导致肠道菌群失调,食用复合活菌制剂可在一定程度上促进双歧杆菌的增殖,能够拮抗模拟失重致肠道菌群失调。     

递增负荷训练和力竭运动对大鼠血液流变学的影响

通过对递增负荷训练和力竭运动后血液流变学指标变化的研究,探讨递增负荷训练对血液流变学的影响。运动训练可以使血液流变性得到改善,从而提高机体的运动能力。     

等离子体活性水对生鲜黄鱼杀菌效果及品质的影响

为开发适用于生鲜鱼肉的新型杀菌方法,本文采用等离子体射流装置分别处理去离子水(1000 mL)1、2和3 min,制备三种等离子体活性水,以肠炎沙门氏菌菌液(10⁸ CFU/mL)为菌体模型,研究活性水的抗菌活性及时效,并对活性水中长效杀菌物质进行测定。采用三种等离子体活性水分别处理表面接种肠炎沙门氏菌的黄鱼片,测定黄鱼表面残留肠炎沙门氏菌数量,并研究其对鱼肉色泽、pH、脂质氧化、亚硝酸盐含量、持水力、气味及味感的影响。结果表明:处理3 min的等离子体活性水表现出最强的抗菌活性,对肠炎沙门氏菌的杀菌率达99.91%,其抗菌活性最高能维持8 h,这主要由于亚硝酸根在酸性条件下分解形成的具有较强杀菌活性的NO·和NO₂·。采用等离子体活性水处理对鱼肉表面肠炎沙门氏菌的杀菌率最高达92.41%,有效抑制鱼肉储藏过程中的腐败,且不会对鱼肉的色泽、pH、脂质氧化、亚硝酸盐含量、持水力、气味以及味感造成显著影响而破坏鱼肉品质。     

射频等离子体活性水处理对火腿发色的影响

探讨射频等离子体活性水（radio frequency plasma activated water,RF-PAW）处理对肌红蛋白颜色及火腿发色的影响,对比亚硝酸钠溶液与RF-PAW的发色效果以及这2 种发色剂用于火腿发色后亚硝酸盐的残留量。结果表明,等离子体处理6 min以内得到的PAW,不会对高铁肌红蛋白（metmyoglobin,metMb）的颜色产生显著影响,会使氧合肌红蛋白逐渐氧化成metMb,颜色由鲜红色变为红棕色;肉眼观察发现,采用RF-PAW、亚硝酸盐溶液（nitrite,NI）作为亚硝酸盐来源来腌制火腿,都能使新鲜猪肉发色,且RF-PAW腌制的火腿发色效果更好,RF-PAW中的活性物质并未对火腿发色造成不良影响;色差分析结果显示,PAW腌制出的火腿有更高的a*、C*值以及更低的b*值,色素含量测定显示,PAW处理的火腿具有更高的亚硝化肌红蛋白色素百分比（43.52%）,说明PAW腌制比NI腌制形成更多的亚硝化肌红蛋白色素,使火腿的红色更深;通过亚硝酸盐残留测定发现,NI腌制的火腿亚硝酸盐残留量为54.45 mg/kg,而PAW腌制的火腿亚硝酸盐残留量为52.79 mg/kg,均小于国标限量值70 mg/kg。该研究结果为肉品低温等离子体保鲜与腌制技术的工程化应用提供理论基础和科学指导。     

黄芪豆豉对气虚血瘀型大鼠血液流变学的影响

研究黄芪豆豉对气虚血瘀型大鼠血液流变学和其相关因子的影响,探讨其益气活血作用及其机制。采用饥饿加疲劳的方法建立气虚血瘀大鼠模型,考察各组大鼠血流变学指标和因子,分析其益气活血作用。在血流变学指标方面:与模型组相比,空白组的全血高、中、低切,黄芪豆豉高、中、低剂量组的低切、高切,差异极显著;空白组,黄芪豆豉低、中组的全血相对指数低、高切及高剂量组的低切差异极显著;而血浆黏度和红细胞聚集指数无显著性差异。在相关因子方面:模型组大鼠血栓素B₂ (TXB₂)和6-酮前列腺素-PGF1α (6-keto-PGF1α)含量比值为0.009 9;黄芪豆豉高、中、低剂量组TXB₂与6-keto-PGF1α比值分别为0.003 5, 0.002 9和0.004 6。黄芪豆豉通过降低气虚血瘀模型大鼠全血黏度、血浆黏度及血液流变学相关因子含量比值,来改善气虚血瘀状态,从而减轻“血瘀证”,具有活血作用。     

葡萄籽粉对高脂膳食喂饲大鼠血液流变学和抗氧化功能的影响

目的:研究葡萄籽粉对高脂膳食喂饲大鼠血液流变学和抗氧化功能的影响。方法:雄性Wistar大鼠60只,按体重随机分为五组,分别为对照组,高脂模型组,葡萄籽粉低、中和高剂量组。对照组给予基础饲料,高脂模型和葡萄籽粉各剂量组给予高脂饲料喂养。低、中和高剂量组分别灌胃0.33 g/kg·bw、1.67 g/kg·bw和3.33 g/kg·bw的葡萄籽粉,连续28 d后,分别测定大鼠血液流变性指标和血清抗氧化指标。结果:与高脂模型组相比,葡萄籽粉干预能显著(p<0.05)降低高脂膳食大鼠全血还原粘度、血浆粘度、红细胞压积、红细胞刚性指数和红细胞聚集指数,提高红细胞变形指数,使血清SOD活性明显增强,MDA生成量显著降低。结论:葡萄籽粉对高脂膳食喂饲大鼠的血液流变性有明显的调节作用,可降低血液粘度,提高血液流动性,减轻脂质过氧化损伤,预防血管早期病变。      

等离子体活性水腌制对猪肉肌原纤维蛋白氧化及结构的影响

研究等离子体活性水(plasma-activated water,PAW)腌制对猪肉肌原纤维蛋白氧化及结构变化的影响.在输出电压20 kV、输出电流0.025 mA条件下,采用等离子体射流装置分别处理蒸馏水0、40、60 s和80 s制备PAW,随后在PAW溶液和纯水中分别加入8％NaCl、3％白糖和0.5％焦磷酸钠配...     

土鳖虫活性肽组分对急性血瘀模型大鼠血液流变学、血脂四项指标及血液因子含量的影响

用胃蛋白酶和胰蛋白酶复合酶系对土鳖虫药材进行仿生酶解,产物经除盐、超滤、纳滤、DA201-C型大孔吸附树脂、葡聚糖凝胶G-25层析、反相高效液相色谱以及半制备液相色谱分离纯化,获得纤溶活力最强的土鳖虫活性肽组分。并研究其对急性血瘀模型大鼠的血液流变学指标、血脂四项指标和血清内一氧化氮(NO)、超氧化歧化酶(SOD)、组织性纤溶酶原激活物(t-PA)和纤维蛋白(FIB)含量等的影响。结果表明:土鳖虫活性肽组分F2能显著降低血液黏度、红细胞压积、血小板计数(P<0.05);与模型组相比,土鳖虫活性肽组分F2能显著降低大鼠血液内甘油三脂(TG)、胆固醇(T-CHO)、高密度脂蛋白(HDL)和低密度脂蛋白(LDL)的含量(P<0.05);大鼠血液中NO、SOD、t-PA含量较模型组明显升高,血清内FIB含量明显减少,差异有统计学意义(P<0.05)。土鳖虫经仿生酶解、分离纯化后制备的土鳖虫活性肽组分F2具有改善急性血瘀模型大鼠血液流变学指标,降低血脂四项指标和改变血液因子含量的作用。     

绿茶、白茶水提物对肥胖小鼠血糖、血脂的干预作用及肠道微生物的影响

实验比较不同剂量白茶水提物和绿茶水提物对肥胖小鼠降糖、降脂的效果及对小鼠肠道菌群的影响.随机将48只小鼠分为正常组(CK)6只小鼠、造模组(HFD)6只和造模干预组36只小鼠.造模组分别采用2.5％、5％、10％白茶水提物和绿茶水提物处理.实验结束测定小鼠血糖、血脂,并通过高通量测序技术研究小鼠肠道微生物菌属相对丰度变...     

Effects of processing on rheology and structure of double cream cheese

Double cream cheese curd was industrially made and post-treated in a pilot scale plant. After storage at 5 °C for 7–9 days, rheological properties of the intermediate and final products were measured using penetrometry, flow curves recording and dynamic testing. Results showed that the curds exhibited timedependent hysteresis of the flow properties and polymer-like dynamic viscoelastic behaviour, independently of the manufacturing stage. Curd mixing at 70 °C and 500 r.p.m. with salt and predenatured whey protein concentrate and dynamic cooling at 20 or 13 °C decreased firmness and dynamic viscoelastic parameters G′ and G″, while tan δ (G″/G′) increased. There was a breakdown of the curd with a decrease in elastic deformation, typical of a solid material and a corresponding increase in viscous flow, characteristic of a liquid. On the other hand, evolution of the rheological parameters was the reverse after heat treatment at 85 °C and homogenization at 20 MPa (first stage) + 5 MPa (second stage). The curd structure was developed with a transition of behaviour to that typical of an elastic solid. Curd cooled dynamically to 13 °C became unstable during subsequent storage. This phenomenon was thought to result from an important breakdown of the curd during dynamic cooling and from aggregation of the milk fat globules during storage.     

Effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut in relation to antioxidant activity

The effects of short-term anoxia pre-treatment on browning of fresh-cut Chinese water chestnut (CWC), stored at 4 °C, in relation to antioxidant activity were investigated. CWC slices were exposed to pure N₂ for 4 h and then stored at 4 °C for 18 d. Anoxia significantly inhibited browning of CWC slices during storage, accompanied by lower contents of malondialdehyde, H₂O₂, and lipoxygenase activity. Furthermore, anoxia induced the activities of superoxide dismutase and ascorbate peroxidase, which could benefit scavenging reactive oxygen species and alleviating lipid peroxidation. In addition, better maintenance of reducing power and free-radical-scavenging activities against α,α-diphenyl-β-picrylhydrazy (DPPH), superoxide anions and hydroxyl was observed in N₂-treated CWC slices, with higher phenolic compounds and ascorbic acid contents. Collectively, these finds suggest that N₂ pre-treatment enhanced enzymatic and non-enzymatic antioxidant activity in CWC slices, and thereby contributed to alleviating lipid peroxidation and maintenance of storage quality.     

血水比例对羊血豆腐凝胶特性和品质的影响

血水比例是调控血豆腐口感品质的关键。本实验以湖羊血液为原料,按照血水比(v/v)1∶0、1∶1、1∶2、1∶3、1∶4、1∶5、1∶6稀释后制作血豆腐凝胶,从血浆纤维蛋白原浓度、动态流变特性、微观结构、质构、保水性等指标的角度,研究血水比例对血豆腐凝胶特性和品质的影响。结果表明:随着血浓度降低,血豆腐储能模量、损能模量弱化,凝胶强度呈下降趋势,同时血豆腐凝胶蒸煮损失和离心损失增大,不易流动水比例下降,水分向慢弛豫方向移动。当血水比<1∶3时,凝胶网状结构稳定性下降,水分易渗出,且不具有动态流变特性,凝胶强度极弱;除弹性外,血豆腐硬度、咀嚼性、内聚性以及黏性均显著降低。血水比≥1∶3时能较好地保持羊血豆腐凝胶的质构特性和持水力,是制作血豆腐的适宜比例范围。      

大豆乳清蛋白的面粉增白效果及其对面团流变学特性的影响

研究了大豆乳清蛋白粉对面粉的增白效果,并进一步研究了在增白过程中起主要作用的脂肪氧化酶活性的变化规律。通过考察不同添加量及温度对面粉增白效果的影响,得出大豆乳清蛋白在添加量为2%、温度为30℃条件下增白效果最好。在此基础上采用Brabender粉质仪测定了添加大豆乳清蛋白粉后面团的流变学特性。粉质实验表明面粉的吸水率增大,面团的形成时间、稳定时间、断裂时间延长,评价值提高,公差指数及面团弱化值减小。     

平衡相对湿度ERH原理在水分活度测量中的应用

目的:介绍目前市场上水分活度测量的主导产品和测量原理。方法:水分活度测量的平衡相对湿度ERH原理。结果:方法简单、操作方便,性价比高,测量准确±0.02。结论:ERH原理已成熟应用于水分活度的测量,产品在食品、生物、医药、卫生、检验检疫、烟草、造纸、园林等领域广泛应用。本文以瑞士ROTRONIC公司的水分活度仪为例,介绍目前市场上水分活度测量的主导产品和测量原理,以及水分活度在不同领域的应用。     

Revised PEC method for measuring water activity

The Proximity Equilibration Cell (PEC) method of Lenart & Flink (1983) for measuring water activity (a_w) in foods was revised by improving equilibration cell design and cell handling procedures. Calibration methods were changed to eliminate time and temperature variation effects on measured (a_w). The PEC cells are inexpensive, easy to use and can measure a_w over the range 0.4–1.0, although accuracy is greatly improved above 0.6. In a study of osmotic concentration of apple (Palacha & Flink, 1987) over 1000 a_w measurements were made over a 3-month period. Values of a_w for raw apple (0.985) and sucrose osmosis solutions were in good agreement with literature values.     

乳清蛋白对脱脂发酵乳的流变特性及贮存稳定性的影响

研究了乳清蛋白对脱脂发酵乳流变学特性及贮存稳定性的影响，在VAYC-370为发酵剂的情况下，分别以质量分数为10％，20％，30％和40％的乳清蛋白替代脱脂奶粉进行发酵，结果表明，乳清蛋白会降低发酵乳凝胶的硬度、提高发酵乳的内聚性，同时发现乳清蛋白可提高搅拌型发酵乳的贮存稳定性．表明发酵乳凝胶的内聚性与贮存稳定性呈正相关关系。     

Characterization of water distribution in xanthan-curdlan hydrogel complex using magnetic resonance imaging, nuclear magnetic resonance relaxometry, rheology, and scanning electron microscopy

Abstract: Xanthan‐curdlan hydrogel complex (XCHC) has been shown capable of retaining moisture up to 5 freeze‐thaw cycles (FTCs); however, moisture distribution in the complex in relation to the hydrogel composition and structure remains uncharacterized. In the present study, magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) relaxometry, rheology, and scanning electron microscopy (SEM) were used to examine the effect of water distribution and interaction with 2.0% aqueous solutions of xanthan, curdlan, and XCHC consisting of equal amounts of both polysaccharides. A gel structure with an indication of syneresis was clearly seen in the MR image of curdlan alone, whereas the distribution of protons throughout xanthan and XCHC samples remained homogeneous and showed no detectable syneresis. The three‐dimensional network, indicated by frequency sweeps, of curdlan was responsible for curdlan's gel structure. The frequency sweep and slope of the storage modulus (G′) of XCHC was significantly closer to curdlan with higher elasticity and less dependency upon angular frequency than xanthan alone. The reduction in XCHC dynamic moduli (G′ and G″) compared to curdlan could be attributed to the formation of wavy layers instead of a fully cured three‐dimensional structure. Addition of xanthan to curdlan restricted XCHC spin–spin relaxation time (T₂) to intermediate and slower exchange regimes, namely approximately 110 and 342 ms, respectively, promoting the polymer's interaction with water while inhibiting interpolymer interactions found in curdlan. A 3rd proton pool with the slowest T₂ seen in curdlan was not found in XCHC, correlating to the absence of syneresis. Practical Application: The combination of texture measurements and discrete noninvasive techniques was found capable of providing insightful understanding of water distribution in a gel system. These techniques may be applied to other hydrogel complexes. The XCHC system investigated has the potential to enhance freeze‐thaw stability in frozen food products by minimizing syneresis due to undesirable temperature fluctuations during distribution and consumer application.