不同盐脱水加工工艺对榨菜质构的影响

采用一盐脱水工艺腌制榨菜和三盐脱水工艺腌制榨菜为实验材料。榨菜质构测定采用TMSTRO专业研究级物性分析仪进行分析。结果表明:不同盐脱水腌制工艺对榨菜的质构影响较大,具体表现为经加工后榨菜的硬度增大,三盐榨菜的硬度一盐榨菜;一盐榨菜的脆度茎瘤芥,三盐榨菜经加工后的脆度原料茎瘤芥;弹性均增大,但三盐榨菜较茎瘤芥的弹性增加幅度不大,一盐榨菜的弹性有大幅度的增加;咀嚼性值较原料也有增加,一盐榨菜的咀嚼性值三盐榨菜;粘结性值呈递增性增加,三盐榨菜一盐榨菜茎瘤芥;内聚性值也有一定程度的增加,三盐榨菜一盐榨菜;3种实验材料测得质构各指标值的变异系数小,表明测得值的离散程度小。     

TPA质构分析茎瘤芥脱水过程中质地变化

应用质地多面分析(TPA)方法,以新鲜茎瘤芥为试材,研究其在风脱水和盐脱水过程中的质地变化。结果表明:茎瘤芥的硬度与脆性、凝聚性与弹性、咀嚼性之间相关性良好,回复性与其他质地参数相关性都较差;在风脱水和盐脱水中各项质地参数之间的相关性表现一致;脆性、凝聚性、弹性、咀嚼性能作为评判茎瘤芥质地的代表性参数。在风脱水期间茎瘤芥质地的代表性参数变化较为稳定,质地特性易于控制,而盐脱水的质地参数变化较大;经过风脱水后除了脆性外,其他质地参数值均低于盐脱水的。试验也表明TPA测试能够较好地反映茎瘤芥各项质地参数的变化规律,适用于茎瘤芥质地品质的客观评价。     

茎瘤芥质量安全分析与控制对策

茎瘤芥(榨菜)是涪陵的特色蔬菜,得天独厚的气候,造就了茎瘤芥优秀的品质,辅以标准化的栽培与管理,必将大大提高其安全性,使涪陵榨菜产业更上新的台阶。文章分析了影响茎瘤芥安全的危害因素,提出了一些解决措施和对策,以期为提高茎瘤芥的品质与安全性有所帮助。     

茎瘤芥皮筋叶绿素提取工艺优化

采用茎瘤芥皮筋为试验材料,采用二次回归正交旋转组合试验优化超声波辅助提取茎瘤芥皮筋中叶绿素,通过试验得出乙醇体积分数、料液比和超声时间与茎瘤芥皮筋叶绿素提取率的回归方程,该二次回归方程模型的F检验达到了极显著水平,可用于对模型的预测。通过回归方程得出茎瘤芥皮筋叶绿素提取优化工艺条件为乙醇体积分数为30%,料液比为1∶2,超声提取时间为80 min。该项研究可为榨菜的深度开发提供理论依据。     

模糊数学评价煮烫处理后的榨菜质构

采用不同煮烫时间处理榨菜,并用模糊数学综合评判法对榨菜质构变化进行感官评价,从而获得榨菜质构品质评价的有效方法。结果表明,榨菜的脆度、硬度、弹性、咀嚼性权重分数从大到小依次为脆度(0.33)、咀嚼性(0.26)、硬度(0.23)、弹性(0.18);随着煮烫时间增加,感官评价隶属度越低,榨菜质构品质下降;煮烫处理0、20 min的榨菜样品综合评分接近于1,榨菜质构品质偏向于很好;煮烫处理40、60和80 min的榨菜质构评分为良好,煮烫处理100 min榨菜质构评语为一般。     

茎瘤芥叶片中叶绿素的稳定性

采用丙酮溶液提取茎瘤芥叶片中的叶绿素,利用紫外-可见分光光度计研究光照、温度、pH值、氧化剂、还原剂和金属离子对茎瘤芥叶片叶绿素稳定性的影响。结果表明：茎瘤芥叶片叶绿素的稳定性受到多种因素的影响,光照、H2O2、VC、酸碱性条件以及Mg2+、Cu2+、Fe3+、Ca2+等金属离子均影响茎瘤芥叶片叶绿素的稳定性。在10～70℃茎瘤芥叶片叶绿素稳定,80℃茎瘤芥叶片叶绿素稳定性下降。中性条件、Na2SO3的存在均对茎瘤芥叶片叶绿素有增色作用。     

软包装即食茎瘤芥的研制

以茎瘤芥为主料,青椒和胡萝卜为辅料,通过单因素试验及正交试验,采用感官评价方法,制得软包装即食茎瘤芥。结果表明:茎瘤芥脱苦最佳工艺为浓度2.5%食盐腌渍30 min;硬化最佳工艺为0.2%氯化钙溶液浓度浸泡20min;软包装茎瘤芥最佳配方为新鲜茎瘤芥70 g,青椒10 g,胡萝卜20 g,食用油10 g,食盐1.5 g,大蒜4 g,红辣椒2.5 g,花椒0.2 g,五香粉0.5 g,味精0.5 g。产品颜色鲜艳、香辣爽脆,且安全方便,为新鲜茎瘤芥资源利用提供了新思路和理论依据。     

1-MCP结合PVC处理对茎瘤芥贮藏品质的影响

为了研究75 μL/L的1-甲基环丙烯（1-Methylcyclopropene, 1-MCP）结合两种不同厚度（30、45 μm）的聚氯乙烯（polyvinyl chloride, PVC）包装处理在4 ℃贮藏条件下对茎瘤芥贮藏品质的影响。结果表明:在贮藏60 d，75 μL/L 1-MCP结合两种不同厚度（30、45 μm）的PVC处理茎瘤芥的硬度分别比对照组高312.13%、266.72%，衰老指数分别比对照组低50.00%、25.00%，保持着较高的商品率；叶绿素的含量分别比对照组高82.48%、89.31%，游离氨基酸总量均低于对照组；肉组织的过氧化物酶（peroxidase, POD）活性分别比对照组低64.29%、51.23%，皮组织的POD活性分别比对照组低73.47%、49.88%；肉组织苯丙氨酸解氨酶（phenylalamine ammonia lyase, PAL）活性分别比对照组低10.60%、10.44%，皮组织的PAL活性分别比对照组低71.23%、64.86%，并抑制了茎瘤芥粗纤维的积累。该研究可为茎瘤芥贮藏保鲜提供了一定的技术指导和理论参考。     

保脆剂对腌制大头菜质构特性的影响研究

采用氯化钙、乳酸钙、丙酸钙3种保脆剂对腌制大头菜进行保脆处理,利用质构仪质地多面分析(TPA)方法定时测定大头菜腌制期间硬度、脆度、弹性、咀嚼性、黏附性和凝聚性6个质构参数的变化情况,并分析各质构参数之间的相关性。结果表明,在腌制期间,TPA测试反映了经保脆剂处理后的大头菜各项质地参数总体呈先上升后下降的趋势,且不同保脆剂间各质地参数下降规律有所差异。大头菜的黏附性和硬度、脆度、弹性、咀嚼性、凝聚性均呈负相关;硬度和脆度具有高度的正相关性(R=0.966);咀嚼性与弹性、凝聚性、硬度呈较好的相关性(R=0.876、R=0.964、R=0.923);凝聚性和硬度、脆度的相关性较好(R=0.934、R=0.919)。     

贮藏温度对新鲜茎瘤芥品质和保鲜的影响

研究不同贮藏温度对新鲜茎瘤芥品质和保鲜效果的影响。茎瘤芥经预处理后,用聚乙烯袋(厚度0.03mm)包装,分别贮藏于相对湿度(RH)85%～95%的0、5、10℃和15℃恒温箱中,统计22d贮藏期内发芽率、腐烂率、商品率,每5d测定抗坏血酸、可溶性固形物、可溶性蛋白等指标。结果表明：0℃和5℃的低温贮藏与10℃和15℃的贮藏条件相比,显著提高了茎瘤芥的商品率,降低了茎瘤芥的发芽率、腐烂率、质量损失率,延缓了抗坏血酸、可溶性固形物和可溶性蛋白含量的下降,但不同温度间总酚和类黄酮变化规律性不强。其中0℃贮藏效果最好,商品率100%、腐烂率0%,贮藏期可达50d,且保持了茎瘤芥良好的品质,贮藏至第20天,其抗坏血酸分别比10、15℃贮藏的茎瘤芥高109%和208%,可溶性蛋白较5、10℃和15℃贮藏高16.7%、59.0%和89.6%。由此可知,10、15℃不利于茎瘤芥保鲜与贮藏,而0℃和5℃对茎瘤芥具较好保鲜效果,保持茎瘤芥良好的采后品质,但0℃总体上优于5℃,故0℃是茎瘤芥最适宜的贮藏温度。     

茎瘤芥叶胡萝卜混合汁复合乳酸菌发酵饮料的研制

研制茎瘤芥叶胡萝卜混合汁复合乳酸菌发酵饮料。方法:以优质茎瘤芥叶子原汁和胡萝卜汁为原料,用嗜热链球菌、植物乳杆菌和嗜酸乳杆菌为菌种,采用单因素试验和五因素四水平正交试验,以产酸量和乳酸活菌数为指标,确定最终发酵菌种和发酵液及发酵饮料口感稳定性的最佳工艺配方。结果:用嗜热链球菌、植物乳杆菌和嗜酸乳杆菌按1:1:1比例作为发酵菌种;发酵液最佳配方为茎瘤芥叶胡萝卜混合汁配比6:4、脱脂乳4%、接种量2%、发酵温度40℃、发酵时间24h;发酵饮料最佳配方为发酵原液中添加蔗糖4%、柠檬酸0.04%、耐酸羧甲基纤维素钠(CMC-Na)0.2%、黄原胶0.03%。     

Influence of precooking on the firmness and pectic substances of three stem vegetables

Edible portions of the stems of sprouting broccoli, asparagus lettuce, and large-stem mustard were compared for total pectin contents, amounts of different pectin fractions, pectinesterase activities and changes during cooking to investigate effects on the textural changes during cooking. Slices precooked for 30min at temperatures below 60°C (broccoli) or 70°C (lettuce, mustard) were firmer after 15 min recooking in boiling water than those directly cooked without precooking. Optimum temperatures for this firming effect of precooking were 50, 60 and 60°C, respectively, and coincided with the optimum temperatures of activity of pectinesterases extracted from the fresh tissues. Analysis of pectin fractions revealed that the firming effect of precooking is related to the shift from the cold water-soluble fraction to sodium hexametaphosphate-soluble and hot water-soluble fractions of pectins.     

When nano meets stem: the impact of nanotechnology in stem cell biology

Nanotechnology and biomedical treatments using stem cells are among the latest conduits of biotechnological research. Even more recently, scientists have begun finding ways to mate these two specialties of science. The advent of nanotechnology has paved the way for an explicit understanding of stem cell therapy in vivo and by recapitulation of such in vivo environments in the culture, this technology seems to accommodate a great potential in providing new vistas to stem cell research. Nanotechnology carries in its wake, the development of highly stable, efficient and specific gene delivery systems for both in vitro and in vivo genetic engineering of stem cells, use of nanoscale systems (such as microarrays) for investigation of gene expression in stem cells, creation of dynamic three-dimensional nano-environments for in vitro and in vivo maintenance and differentiation of stem cells and development of extremely sensitive in vivo detection systems to gain insights into the mechanisms of stem cell differentiation and apoptosis in different disease models. The present review presents an overview of the current applications and future prospects for the use of nanotechnology in stem cell biology.     

Culture systems for pluripotent stem cells

Pluripotent stem cells have the capacity to self renew and to differentiate to cells of the three somatic germ layers that comprise an organism. Embryonic stem cells are the most studied pluripotent stem cells. Pluripotent stem cells have also been derived from adult tissues. Both embryonic and adult stem cells represent valuable sources of cells for applications in cell therapy, drug screening and tissue engineering. While expanding stem cells in culture, it is critical to maintain their self-renewal and differentiation capacity. In generating particular cell types for specific applications, it is important to direct their differentiation to the desired lineage. Challenges in expansion of undifferentiated stem cells for clinical applications include the removal of feeder layers and non-defined components in the culture medium. Our limited basic knowledge on the requirements for maintaining pluripotency of adult pluripotent stem cells and the lack of appropriate markers associated with pluripotency hinders the progress toward their wide spread application. In vitro differentiation of stem cells usually produces a mixed population of different cell lineages with the desired cell type present only at a small proportion. Use of growth factors that promote differentiation, expansion or survival of specific cell types is key in controlling the differentiation towards specific cell lineages. A variety of bioreactors for cell cultivation exist and can be readily adapted for stem cell cultivation and differentiation. They provide a well-controlled environment for studying the process of stem cell propagation and differentiation. Their wide use will facilitate the development of processes for stem cell application.     

利用芦笋弃料制作饮料的工艺研究

以芦笋弃料为原料,经加热软化、榨汁后,用β－环状糊精(β－CD)掩盖苦味,研制成芦笋饮料。研究表明,芦笋弃料在温度为85℃,柠檬酸含量为0.2％的热烫液中软化7min,出汁率高,色泽淡。原汁中添加1.0％～1.5％的β－CD可有效地掩盖芦笋的苦味,而风味不受影响。芦笋原汁60％、β－CD1.2％、甜味剂(蔗糖：阿斯巴甜为100∶1)2.5％、柠檬酸0.15％,加水至100％,制成的饮料具有芦笋的清香味,甜酸适口。     

四川四大腌菜发展战略的研究

从四大腌菜产业的概况入手,通过分析四川四大腌菜发展面临的挑战,获知四大腌菜存在的问题。进一步研究四大腌菜发展面临的机遇,提出四大腌菜的发展战略。四大腌菜发展战略为:建立"市场准入机制"和"终身出局机制";转变产业发展模式;加强同其它产业的联系;研发功能性腌菜满足市场需要;深挖四大腌菜的文化内涵;建立四大腌菜产业人才培养机制;引入现代营销理念,创新营销手段;重点扶植腌大头菜的发展。