最近的一次作业——翻译（blogcn: 2006-10-18 22:12）

12
Probiotic functional foods
T. Mattila-Sandholm and M. Saarela, VTT Biotechnology, Espoo

12.1 Introduction: the health benefits of probiotic foods
The area of food for health has been identified as a priority area for research in
Europe. This is based on the recognition that there is enormous potential for
improving health through food. Furthermore, diet is a major focus of public
health strategy aimed at maintaining optimum health throughout life, preventing
early onset of chronic diseases such as gastrointestinal disorders, cardiovascular
disease, cancer and osteoporosis, as well as promoting healthier ageing.
Although the highly complex relationship between food and health is still poorly
understood, recent research advances in different disciplines provide promising
new approaches to improve our understanding. The growing demand for
‘healthy’ foods is stimulating innovation and new product development in the
food industry internationally. Indeed, the food industry has a central role in
facilitating improved eating practices through the provision and promotion of
healthy foods.

Probiotics are live microbial food supplements which benefit the health of
consumers by maintaining or improving their intestinal microbial balance.1 Due
to their perceived health benefits probiotic bacteria have been increasingly
included in yoghurts and fermented milks during the past two decades. Most
commonly they have been lactobacilli such as Lactobacillus acidophilus, and
bifidobacteria often referred to as ‘bifidus’ (see Table 12.1).2 A major
development in functional foods pertains to foods containing probiotics and
prebiotics which enhance health-promoting microbial flora in the intestine.
There is growing scientific evidence to support the concept that the maintenance
of healthy gut microflora may provide protection against gastrointestinal
disorders including gastrointestinal infections, inflammatory bowel diseases and
even cancer. The use of probiotic bacterial cultures stimulates the growth of
preferred micro-organisms, crowds out potentially harmful bacteria and
reinforces the body’s natural defence mechanisms.

Before a probiotic can benefit human health it must fulfil several criteria: it
must have good technological properties so that it can be manufactured and
incorporated into food products without losing viability and functionality or
creating unpleasant flavours or textures; it must survive passage through the
upper gastrointestinal tract and arrive alive at its site of action; and it must be
able to function in the gut environment. To study the probiotic strain in the
gastrointestinal (GI) tract, molecular techniques must be established for
distinguishing the ingested probiotic strain from the potentially thousands of
other bacterial strains that make up the gastrointestinal ecosystem. Techniques
are also required to establish the effect of the probiotic strain on other members
of the intestinal microbiota and importantly on the host. This includes not only
positive health benefits, but also demonstration that probiotic strains do not have
any deleterious effects. Armed with this knowledge, the probiotics can then
enter human clinical pilot studies that attempt to assess their clinical health
benefits to consumers (Table 12.2).3, 4

12.1.1 Demonstration of Nutritional Functionality of Probiotic Foods
(FAIR CT96-1028)
Europe has traditionally had a leading position on the probiotic market.
Considerable confusion and scepticism, however, exists on the side of consumers,
consumer organisations and certain quarters of the scientific community about the
claims associated with probiotic products. This greatly hampers further
exploitation of functional foods containing probiotic bacteria and weakens the
market position of European producers in the face of competition. To eliminate
these hurdles, to speed up adaptation of the probiotic food technology and to
enhance the attractiveness of new probiotic foods, it is essential to demonstrate
the up-to-date basis for marketable claims by presenting the health and nutritional
benefits of probiotic bacteria and foods. Special emphasis should be put on
intestinal integrity and immune modulation, exploitation of validated methods for
the selection of novel probiotic bacteria and foods, and dissemination of the
obtained knowledge to the extended audiences consisting of industries,
authorities and consumers. The Probdemo project was initiated to demonstrate
the value of probiotic products to European consumers. The project objectives
were divided into four interactive tasks (Table 12.3):

1. To establish a scientifically based selection of probiotic bacterial strains
currently available for functional foods. Six probiotic strains representing
Lactobacillus and Bifidobacterium species were chosen for demonstration
purposes.
2. To demonstrate the beneficial value of probiotic products in human pilot
trials both in children and adults. Initial tests showed that probiotic strains
did not have any deleterious effects in healthy children or adults.
Furthermore, probiotic strains were shown to be effective in the treatment
of infants with food allergy and small children with rotavirus diarrhoea. The
effect of probiotics was also demonstrated in adults with inflammatory
bowel disease (IBD).
3. To demonstrate and meet the functional and technological requirements
essential for the industrial production of probiotics as functional foods. This
has been established by studying probiotic strain properties in vitro and
reflecting these results to the clinical situations. The main focus has been on
demonstrating adhesion in vitro and in vivo using human biopsies, on
demonstrating the technological criteria for probiotic products, and on pilot
production of probiotic strains.
4. To disseminate the knowledge and results to extended audiences consisting
of industrial users, authorities and consumer organisations. This has been
established by annual workshops (Workshop 1 was held on Safety of
Probiotics in 1996, Workshop 2 on Probiotic Research Tools in 1997,
Workshop 3 on Functional Food Research in 1998, Workshop 4 on
Functional Foods in 2000).5–8

The project participants and institutes collectively have wide experience in
this research area, building on the results of former EU programmes on lactic
acid bacteria and probiotics. The industrial partners have long traditions in the
markets of functional foods with special reference on probiotic products. VTT
Biotechnology, Finland, has the role of coordination and dissemination of
activities and demonstration tasks on probiotic strain properties, technological
properties and clinical testing on adults. The University of Wageningen,
Netherlands, has the key role of demonstrating the activity and viability of
probiotic strains in human clinical trials by using molecular methods including
PCR, in situ hybridisation and DGGE/TGGE. The Catholic University of
Piacenza, Italy, has the role of showing the adhesive and aggregation properties
of the strains to be demonstrated. The University of College Cork, Ireland, has
profound expertise on human gastroenterology, clinical testing with adults and
immune modulation activities of probiotics. University of Turku, Finland, has a
long scientific tradition of clinical testing with children and the links between
clinical pediatrics and functional foods. The industrial partners Valio Ltd.
(Finland), Arla (Sweden), Nestle´ (Switzerland) and Christian Hansen Laboratories
(Denmark) have sound basis of industrial production of probiotic products
and long experience on functional foods market as well as research in this area.
This industrial role is of utmost importance in selecting the strains to be
demonstrated, preparing the products to be developed and in verifying their
beneficial effects.

12.2 Selecting probiotic strains
The theoretical basis for selection of probiotic micro-organisms illustrated in
Table 12.4 and Fig. 12.1 includes:
• safety
• functional behaviour (survival, adherence, colonisation, anti-microbial
production, immune stimulation, anti-genotoxic activity and prevention of
pathogens such as Helicobacter pylori, Salmonella, Listeria and Clostridium)
• technological aspects (growth in milk, sensory properties, stability, phage
resistance, viability in processes).

In general, strains for pilot testing should be selected based on established in
vitro scientific data. Naturally, the safety of probiotic strains has been of prime
importance and new guidelines have been developed.9–13 Current safety criteria
and functional properties for successful probiotics have been defined in recent
reviews.14–16 These include the following specifications:
• Strains for human use are preferably of human origin.
• They are isolated from healthy human GI tract.
• They have a history of being non-pathogenic even in immunocompromised
hosts.
• They have no history of association with diseases such as infective
endocarditis or GI disorders.

The significance of human origin has been debated recently, but most if not
all current successful strains are indicated to be of human origin. Similarly, the
importance of the ability to colonise the human gastrointestinal tract has been
questioned. However, most current strains are reported to persist in humans at
least temporarily as measured by faecal counts following ingestion. Acid and
bile stability are self-evident properties for any strain expected to have effects in
the intestinal tract. Ability to adhere and persist are also closely related to
potential immune effects. It is likely that some mechanisms of adhering and/or
binding to the intestinal cells are required. Thus controlled comparable studies
on in vitro model systems, such as the Caco-2 cell line, are of importance.17, 18
Adherent strains of probiotic bacteria are favoured since they are likely to persist
longer in the intestinal tract and thus have better possibilities of showing
metabolic effects than non-adhering strains. At least one of the commercial
probiotic strains has been demonstrated to adhere to the colonic mucosae in
vivo.19

To have an impact on colon flora it is important for probiotic strains to show
antagonism against pathogenic bacteria via anti-microbial substance production
or competitive exclusion. Enormous research efforts have focused on bacteriocin
research. However, the mode of action and efficacy of bacteriocins in the gut is
not known for probiotic bacteria. Although probiotic strains may produce
can only be limited, since traditional bacteriocins have an inhibitory effect only
against closely related species such as other Lactobacillus or on sporeformers
such as Bacillus or Clostridium. However, low molecular weight metabolites
(and secondary metabolites) may be more important since they show wide
inhibitory spectrum against many harmful organisms like Salmonella,
Escherichia coli, Clostridium and Helicobacter.20–22

12.2.1 Development of cultures aimed for functional probiotic foods
Probiotic dairy foods and cultures have a long history and large consumption in
the Nordic diet. Industrial products, including cultured dairy products, and their
probiotic properties have been studied for many decades. The objective of the
Nordic programme (from 1994 to end of 1997) was to validate industrial
probiotic strains with regard to in vitro functionality. Strains were provided by
project participants Arla (Sweden), Christian Hansen (Denmark), Norwegian
Dairies (Norway) and Valio Ltd (Finland). Strains studied included the
following: Lactobacillus paracasei subsp. paracasei strains E-94506 and E-
94510, Lactobacillus rhamnosus strains E-94509 and E-94522, Lactobacillus
acidophilus E-94507, Lactobacillus plantarum E-79098, Lactococcus lactis
subsp. lactis E-90414, L. lactis subsp. cremoris E-94523, Bifidobacterium
animalis (lactis) E-94508 and Bifidobacterium longum E-94505. The studies
included research on the in vitro cytokine release effects, adhesive properties,
anti-mutagenicity and behaviour in the gastrointestinal tract models (TNO
gastrointestinal tract model in the Netherlands, and the SHIME ecosystem at
Ghent, Belgium). Also technological and production properties were assessed.

Assessment of adhesion properties
Adhesion of probiotic strains to human intestinal cells and the following
colonisation of the human gastrointestinal tract has been suggested as an
important prerequisite for probiotic action. Adhesion verifies the potential of the
strain to inhabit the intestinal tract and to grow in intestinal conditions. Adhesion
also provides an interaction with the mucosal surface facilitating contact with
gut-associated lymphoid tissue mediating local and systemic immune effects.
Thus, only adherent probiotics have been thought to induce immune effects and
to stabilise intestinal mucosal barrier.23 The Nordic programme project results of
in vitro adhesion assays gave a clear indication of differences and variation
between assays and different strains.24, 25 It was evident that in addition to Caco-
2 cell line experiments, other test systems were also needed to characterise the
adhesion potential and different adhesion mechanisms. The adhesion system was
also used to study the anti-invasion potential of probiotic stains. Different
probiotic strains show relatively different behaviour in invasion inhibition and
novel methodologies are needed to assess these properties in a way that relates
them to clinical situations. Adhesion experiments indicate clear differences in
the colonisation potential of different probiotic strains and, when later connected
with clinical data, may provide a useful basis for selection and method
development for future probiotic strains.17, 18 Lately adhesion assays have also
been applicated to human ileostomy glycoproteins (modelling for small
intestinal mucus), showing once again different characteristics of the probiotic
features.26

In vivo adhesion studies using colonic biopsies
Faecal samples have been used in most colonisation studies on probiotic
bacteria.27, 28 These, however, reflect only the bacteriological situation in faecal
material and do not give an accurate picture about the situation in different parts
of the gastrointestinal tract or in the mucosal layer of the gut. There are
advantages in taking biopsy material from colonoscopy patients: in this way
tissue samples have been obtained, not only from the rectal-sigmoidal region,
but also from other parts of large intestine (ascending, transverse and descending
colon). As a result the preferential adhesion of a commercial probiotic strain
(Lactobacillus GG) to the descending part of large colon was detected by using
biopsy material. This probiotic strain was shown to survive in the gut epithelium
for several days after consumption of the probiotic preparation was stopped and
even after the strain could no longer be detected in faecal samples.19 Johansson
and co-workers have also demonstrated the adhesion of different Lactobacillus
strains to rectal mucosal biopsy samples obtained from volunteers who had
consumed fermented oatmeal soup.29

Immunological assessment
Gut-associated lymphoid tissue may have contact with adhesive probiotic
preparations and therefore adhesion is one way of provoking immune effects.
The Nordic network studied the interactions of probiotic strains and dairy
cultures (Lactobacillus bulgaricus, Streptococcus thermophilus) with cytokine
production (human TNF-, interleukin-6, interleukin-10, interleukin-12, TGF-,
and interferon-). Probiotic strains which had passed through the in vitro TNO
gastrointestinal tract model were also assayed for their ability to induce cytokine
production (TNF-, interleukin-6).30 The main goal was to investigate whether
probiotic strains stimulate the immune system in vitro through cytokines. IL-6
production showed considerable variation between experiments performed with
live bacteria. Test strains were not observed to induce IL-10.31 Efforts were
made to develop new methods to measure early cytokine responses by detection
of mRNA by Northern hybridisation. This method proved more sensitive than
the ELISA and has demonstrated that probiotic strains indeed produce IL-10 and
IL-1b. Further investigations focused on analysis of the pathway of cytokine
induction by probiotics, estimation of the effect of serum proteins, interaction
between probiotics and human cell surface molecules.32

原来我遮住了自己生活中的阳光（blogcn: 2006-10-18 18:47）

食品工程的课结束了，没有考试，最后的考核是两个班的人一共翻译两本书，然后按小组用PPT讲一下自己的主要内容。于是，我害怕了。我从来不喜欢这种分组的形式，因为我的组员都不是 我选的。事实按照我为自己设想的最坏的思路发展下去，七个人的小组，我做了内容最多、最难翻译的一部；今天下午的所谓的答辩，根本没有人关心，有人连来也 不来。本来各自讲各自的内容，成了我跟一个要好的朋友的活儿。恶心的结果是可想而知的。我没有什么权力去要求别人；事实上，我根本不忍去要求别人，别人要 考研，别人根本不在乎自己的成绩，那对他们完全没有用，90分和60分的成绩没有区别。我请自己不要难过，好吗？

辅修成绩出来了，我进入了能够参加最后双位学选拔考试的大名单。但是成绩依旧有问题。我的一门课的成绩本来是95分，结果也不知道为什么录成了80分，去找 教务处的老师，她让我去找任课老师；可是，任课老师在辅修的第一学期成绩出来的时候已经明确地告诉我，是95分，80分确实是有问题的。然而，问题还没有 解决，辅修的成绩单也没法打，出国成绩单于是一拖再拖。我请自己忍耐一下，好吗？

P&G的第一轮考试轻松通过。一天早上P&G的电话要我去参加他们的英才见面会。于是，满心喜欢地第一次以正当的理由走进了五星级酒店。然而，拥挤的会场，无聊的 演讲，冗长的内容。四点多没有吃饭就去了酒店，去了才知道没有饮食方面的照顾，而且要至少到九点才结束。快十点的时候出来，饥肠辘辘。这就是世界五百强 的、有着上百年历史的外企。我请自己不要失望，好吗？

一天接到系里一个老师的电话，要我过去帮忙做个研究生的项目。我答应了。老师先介绍了一个内容，我首先想到的解决方法就是分子克隆。老师和研究生姐姐也认可了，可是说这样的东西系里三年内都没有人做过了。我 说我还比较熟悉一些过程，暑假在IBP做了几乎一个假期，也学了些东西。研究生姐姐说那就好，让我回去找找资料。于是找文献，结果发现跟我的大思路类似的 东西在今年就有国外的人发了文章。不知道该怎么办了。化学合成或者是诱变育种的方法我真的一点都没有接触过。我请自己不要放弃，接着努力，好吗？

食堂师傅四毛钱的米饭打的像两毛半，一碗面不知道有多少盐，咸得我只吃了不到十根（不是裤带面），收拾碗筷和残食的师傅把残食弄到了我身上，吃出小虫虫，我没说话就走了。我知道，可能我的一次投诉，就会让一个师傅下岗或者停职，至少写个检讨吧。大家都不容易，也许他或她的背后就是一个家庭，一个要供养的大学 生，一个生病的老人。我请自己不要强求，好吗？

刚洗好的衣服，掉到了地上，满是灰土。我请自己不要郁闷，再洗一遍，好吗？

出国申请的事情依旧进展缓慢，我的自卑到了无以复加的地步。我请自己自信一些，好吗？

跟MM闹别扭了。就算先是她的不对，但后来是我的错。我请自己不要冲动。对不相识的人都笑脸以对，而对MM却那么苛刻。我请自己宽容一些，好吗？

刚才同学来电话，说是Unilever的招聘宣讲会，问我去不去。我说去。我让自己不要把自己逼到一个没有退路的死胡同里，好吗？

我要自己看到自己的优点，看到未来的光明，不要总是觉得自己这也不行那也不好；我要自己从阴影中走出来，想想过去其实我实现的事情也不比没有实现的事情少多 少；我要自己相信自己能有一个美好的未来；我要自己笑一笑，不要总在伤心的时候望着窗外的天空听悲伤的歌曲；我要自己不要总是对别人宽容，而对自己或是 MM苛刻；我要自己在晚上躺在床上的时候能够想想自己的收获，不要总把焦点集中在自己的过失上；我要自己不要总是在别人有困难的时候去帮忙和安慰，而在自 己遇到困难的时候却总是一个人面对，连心里的那一扇透气的窗都紧闭不开。

好吗？

日子依然继续，不好不坏（blogcn: 2006-09-26 19:51）

因为去新加坡的师兄走后那个项目就搁置下来了，再加上相关负责老师的从这学期开始的一学期的产假，PHBHHx的纳米级颗粒的制备的项目去不了了，这让我难过了两天，毕竟认认真真地看 了很多资料。老师不冷不热的回信让我的一腔热情碰得冰冷。于是只能周一下午去找了另一位老师，老师很好，聊了一个多小时，答应我去跟着她的课题组做。其间谈到去新加坡的那个师兄，老师笑兮兮充满喜欢地说：“**说他在我的组里做了什么什么，其实基本上啥也没做，推荐信只要写得不要太那个（太夸张）就行了。 ”其实国外教授现在也知道，中国学生的推荐信基本是自己写的，然后找老师签字。。。这下好了，又得重新找资料、看文献，熟悉一个新的研究内容。。。

说到了推荐信，其实昨天早上就在跑这件事情。思来想去自己系里没有什么太牛的老师，于是就去找了大二时教过我物理化学的理学院的从日本回国的大牛（好像SCI就有50多篇~~ ）。老师倒是热情得出乎我的意料。。我去他上课的教室等他，他一进来看见我在，直接在第一排大声说：“小于，你怎么来了？”然后径直往我坐的后排走。弄得我怪不好意思的，没想到老师还记得我~~ 


后来他也答应给我写推荐信了，只是我得提供自己资料，他才能写出positive的内容。教授说，出国一定要对自己今后的发展有好处，要不然不出也罢，为了出国而出国是很dangerous的。那个dangerous吓得我一哆嗦。

给大一的小朋友们做经验交流，没想到最让全场掌声雷动的竟然是那句“真正的爱情还是很值得追求的东西，那是种很美妙的感觉”。已经有阵子没有在上百人面前讲 过话了，竟然有些紧张。于是，趁机发挥吧，“我自从离开学生会就很少有机会在这么多人面前讲话了，因此，讲你们珍惜每一个在很多人面前讲话的机会，这至少对你是一个锻炼。”

尽管暑期实习的答辩我很不满意，但依然取得了优秀的成绩。做与不做是不一样的，加上我10个打印页的报告，老师是能看出好坏的。但如何能在众人面前把握好自己表达的重点，有简有繁地表达自己的思想，的确是我应该加强的地方。这两天去了baidu和P&G的校园宣进会，明白了原来大牛都是怎样炼成的 了。只那在近千人面前的自如的谈吐，便不是我这等小辈一朝一夕可以练成的。

昨天去找院里的辅导员签P&G的推荐信，里面要填英语水平，于是我写了CET6&TEM4。MM问我为什么不写TOEFL&GRE ，我愣了一下，说它们都不是资格认证考试。是啊，那两个考试是我为了出国才考的，我提醒自己，别忘了自己那个大洋彼岸的遥远的梦。

我的生活轻闲得让保研的同学都羡慕我的随心所欲，但谁又知道我心中的苦。。。毕竟保研的人已经有了一年后的着落，考研的人依靠三个多月的奋斗至少可以让自己 问心无愧，而我想起未来等offer的日子，便一阵冷汗，我可能在别人已经开始读研究生或者开始工作后，依然过着没有着落的日子，虽然我已经做好心理准 备，但我依然无法确定地想像出那是一种怎样的煎熬。现在确定自己的申请方向也让我头疼不已。。。而面对PS，我甚至不知道自己是谁。

拨云见日（blogcn: 2006-09-20 09:15）

自己的事情只有自己能够解决，心理上的问题尤甚。上周日的时候还因为一些事情很难受，竟然伤心到肝都疼，几乎泪流满面，自己都不明白为什么，只是突然好伤心。

于是申请的事情先暂时地放一小下，从简单的事情出发，给自己一种努力的状态。开始看文献了，关于生物材料的，羟基丁酸酯-羟基己酸酯的共聚物 （PHBHHx）的纳米级颗粒的制备。这是一个跟我关系很好的已经拿着全奖去新加坡的师兄的毕设内容，希望能尽快看完他的资料，之后进实验室跟着其他师兄 做相关的内容。

虽然出国的事情仍是压在我肩头上的挥之不去的重担，但是现在不像前几天那样总想着这件事情，心里就会轻松一些。占师兄说得对，走的路有时候恰恰不是自己设想的任何路中的一条，想得太多反而给自己太大的压力。有时候我就是固执到给自己一个放松的理由都不行。

TEM4（英语专业四级考试）的成绩终于出来了，我通过了，虽然成绩并不高，但我已经满足了，看着英语专业还有许多人没有通过，心头还是闪过了一丝小小的得意，毕竟只是随便考了考；那考试跟TOEFL、GRE的考查内容和方式差得太多~~

我在学生会的部员，现在已经当上了主席，让我不禁感叹时间的飞逝，想想自己的本科还有不到一年了。那小兄弟邀请我去给大一的小朋友们做一次报告，基 本就是经验交流吧，我同意了。MM说像我这么彪悍的人，会把小朋友们吓到的。我笑，只怕把小朋友们都带坏了，因此还是准备一下，不能去了胡抡~~ 否则一定会把有些小朋友打击到的。

今天用几种GPA的算法，都能比较大地提高我的GPA，浙江大学的算法竟然能把Overall的GPA算到将近3.30，我彻彻底底地服 了；UCLA的算法也能把我的GPA算到3.0以上。只是这样的GPA我都有些不敢写到申请材料里，怕小米自己用标准算法算过后发现有比较大的出入。自己 出不去是小事情，失了诚信耽误了弟弟妹妹们的前途是大事~~ 但至少让我放了些心，我的GPA也是可以到3.0的。这学期还选了选修课，是自己学院开的，希望拿到高分来弥补自己GPA的不足。我这已经是在为明年的申 请做准备了。把专业课考得尽量高也是在我看来和出国申请同等重要的事情，我不想再被GPA这东西折磨了。

一切似乎都开始慢慢进入正轨了，我要再一次把命运牢牢地掌握在自己的手中。