- Email: [email protected]
Food science and technology on the internet
Feature
Food science and The Internet, in its various manifestations, is rapidly becoming both a major means of communication
and an indispensable
information tool for those who know how to use it. In the 199Os, with the advent of the Internet’s rapidly expanding user-friendly interface, the World Wide Web, knowing how to use it has spread far beyond computer experts skilled in a
technology on the Internet*
range of arcane techniques, to virtually anyone with a subscription to a service provider and a PC (or any other computer type) fitted with a modem linked to a telephone line.
J. Ralph Blanchfield
Across the world, government departments, international and national institutions, universities, banks, companies and individuals are either already ‘on the Net’ or hurrying to get on. The already substantial opportunities both to acquire and to communicate food science and technology information may be expected to proliferate and expand as fast as the Internet itself.
Nobody ‘owns’ the Internet, nobody controls it. It is a worldwide anarchic network of computer networks linked via the telephone system in such a way that if any of them is out of action, communications find a route through the rest of the network. It is a means of interrogating computers and databases throughout the world (e.g. of libraries, universities, research institutions, govemment organizations and agencies, and commercial organizations that have chosen to act as ‘servers’) and acquiring or conveying data, text and computer files of all kinds. (Note: being on the Internet does not mean that one’s own computer is open to entry or interrogation, unless one wishes that to take place.) Information is transferred by a common protocol that is recognized and actioned by any computer in, or linked to, the network, regardless of its make or its operating system. The Internet’s origin is traceable back to the 1960s when the US Defense Department established ARPANET (Advanced Research Projects Agency Network), a computer network that would continue to maintain communications even if part of it was destroyed by nuclear attack. During the 1970s and 198Os, academic institutions in the USA established a computer network that became linked into ARPANET. Then the US National Science Foundation established a network. which was initially linked to ARPANET. but subsequently operated separately as NSFNET. Around 1990 it was opened to general use, and became recognized as the Internet. Around 1990, at the European Particle Physics
*Readers should be aware that there are aspects of e-mail security, such as viruses on imported programs and ‘hacking’. These are subjects too wide to address in this article. J. Ralph Blanchfield is at 17 Arabia Close, Chingford, London, UK E4 7DU itel: +44-81-524-1800; e-mail: [email protected].
Trends in
Food Science & Technology
January
1996 [Vol. 71
Laboratory (CERN, in Geneva, Switzerland) the World Wide Web (WWW) was originated as a user-friendly interface with the Internet, and was developed into a publicly usable system by March 1993, initiating evolution at an escalating rate amounting to revolution. It is because of its history that, until very recently, the Internet developed almost entirely as a US phenomenon, with a US ‘culture’. Likewise, US users have a longer-established culture of using the Internet, and still make up the majority of users (75% according to the most recent survey). However, this situation is rapidly changing, especially since the advent of the WWW.
The Internet One way of describing the Internet is in terms of its facilities. These are numerous, but for the purposes of this article the most important are: electronic mail (e-mail for short); the WWW; indexes, search engines and databases; mailing lists; newsgroups; ftp (‘file transfer protocol’); and ‘chat’ systems. Use of any of these facilities involves a modem link with your service provider’s server computer (or your computer may already have a direct link via your employer’s or university’s local network); and if your service provider is in your local telephone area, no matter where in the world your communications are going to or coming from, all your online phone time is at local call rates.
E-mail E-mail software usually forms part of the package you receive from your service provider. It is a means of communicating with one recipient, or simultaneously with any number. It is faster to send an e-mail message than an equivalent fax, and it is charged at local phone call rates. However, although it is faster and cheaper to do the sending, the time it takes for the message to be received depends on the routing of the message, which eventually reaches the recipient after being passed on by many intermediary machines (this can take many hours, and is not controlled by the sender), and also requires recipients to log onto their computers regularly. E-mail is also the means of posting messages to, and receiving them from, mailing lists (see below). 01996,
Elsevier Science Ltd
The use of html permits certain words or phrases (or graphics), designed to be ‘hot spots’, to stand out (e.g. in a different colour and/or underlined) from the rest; thus, when the cursor is placed on one such hot spot, and the computer mouse is clicked, it automatically takes the reader to another page to which the word or phrase refers. A single page may contain numerous links, which readers may follow (or not) as the fancy takes them. Navigating a Web site is therefore nothing like reading the pages of a book in sequence. Moreover, unlike a paper page, a ‘page’ on the WWW is of no fixed size; it corresponds to a computer file and is as short or as long as c!DOClYPE HTML SYSTEM “html.dtd”>cHTML> cBODY>
Welcome to very long pages. the Home Page of the Institute of Food Science & Technology, more familiarly known as In every field of activity and interIFST.~H~XP> eH3>cB4FST is the independent incorporated professionalc/As qualifying body for food scientists and available on the WWW. There are ,technologists. Its purposes are :-~BxIH~~~P%UL>~LI>to serve the also numerous organizations of all public interestc/Az by furthering the application of science and kinds (and even individuals) with technology to all aspects of the supply of safe, wholesome, nutritious and attractive food, home pages, with hundreds more nationally and internationally;to uphold professional spot links with other pages (of the standards of CA HREF=“grades. htm”>competence and integrity4A>cIULs
2
Trends in Food Science & Technology January 1996 [Vol. 71
that the URLs of the main university, government or company computers change less often than the URLs of specific subdirectories, such as a given department or database address, which may be reorganized periodically. So, if you consistently find that you cannot access a given site, try typing in only the beginning of the address, ending after the country or main network code (e.g. ‘.com’, ‘.edu’, ‘.uk’, ‘.au’ or ‘.ca’), possibly followed by a slash (/) mark. This should get you to the site’s main computer; you can then look for the updated links to the relevant department.
Weave your own Web For those accustomed to using ‘Windows’ and word processors, writing html files with the aid of an html text editor (software acquired free by downloading from the Internet) is a skill very quickly and easily acquired from any of the numerous books, Internet magazines (such as Internet, Internet Today, NetUser and .net, all available in newsagents), or articles on the WWW itself - there are several useful links, including one to an interactive tutorial, on Netscape’s own page: http://home.netscape.com/assist/net_sites/index.html Good layout and graphic design of Web pages, which involve different criteria, and have to be achieved by different methods from on-paper design, are another matter and outside the scope of this article. Having a home page does not mean that your computer has to remain online or that those accessing it can ‘invade’ your computer; your home page is maintained (for an annual fee) in the computer of your service provider. You can modify and update your own page(s) but others accessing it cannot. You can, however, provide interactive pages through which a reader can send you feedback.
Web indexes,search engines,special subject databases Web indexes, which are updated with thousands of new entries daily, cover all topics in main categories and several levels of sub-categories, each topic and subtopic name being a hypertext link, so that you can narrow down your topic to a list from which you select the item you want and bring it up on screen. Increasingly, however, these indexes provide an alternative option that allows them to be interrogated as databases using keyword(s). Search engines operate wholly as such databases. See Box 3 for further information.
Mailing lists (‘listservs’) An Internet mailing list is maintained on a ‘listserver’ computer, and you join it (at no cost) by sending a ‘subscribe’ message plus the name of the list and your first and last names, by e-mail to the listserver address, which is the address of the computer that ‘manages’ the list. For example, should 1 wish to join the FOOD-LAW list, I would send an e-mail to the listserver address ([email protected]). I would type: subscribe FOOD-LAW
Ralph Blanchfield
as the body of my message. Inclusion of the name of the list is important as some listservers run a number of Trends in Food Science & Technology January 1996 [Vol. 71
fi.ilniul
ark -* .~ Royal Veterinary & Agricultural University: hu&fwww.fc tici.kvl.dk
http~/~.tuns.ca:8O/foodscif
Technical University of Nova Scotia:
http;//www.umanitoba.c~AgricuIture/Agriculture.html
University of Manitoba:
http#www.fo&ci.uoguetph.ca
University of Guelph:
httpY/www.afns.ualberta.ca
University of Alberta:
N~ingham University:
h~~~~.unl.ac.~k:8~lc~e.h~ml
University of North London:
~~/~.doc.mmu.at.uWhoiACi/courses.html
Manchester Metropolitan University:
https’fwww.food.leeds.ac.uk/food.htm
University of Leeds:
hhttpz//www.fen.bris.ac.uk/mech/frperc/frperc.htm
University of Bristol (Food Refrigeration and Process Engineering ResearchCentre):
UK
http;//www.kc.lu.se/inl/
Lund University:
Acadia University:
http#ace.acadiau.ca/science/nutr/home.html
Sweden
Canada
http;l/www.massey.ac.nz/-wwtech/old/TechnologyHome.html
University of QueensJand:
httpi/www.uq.oz.au/fst/
New Zealand Massey University:
http$vww.spb.wau,nl/lmt/
Wageningen Agricultural University:
5opher~/gopher.acs.ohio-state.edu:70/00/OSU%20Colleges% 20and%ZQDi3partment~/OfficeY~2O~f~~2DAdmission~%2~a~d %2~Fina~ciat%2OA~d/Admissions%2~lnformatjon% 20-%200hio%20StatelUnderg~aduate”~20tnformat~on% ZO-%20 Ohio %20 State/maiors/fdx
Ohio State University:
http#www2.ncsu.edu/ncsu/caIs/food-science/indexexhtml
North Carolina State University:
http#anrwww.unl.edu/ianr/foodsci/fstfpc.htm
University of Nebraska:
http-//www.fsci.umn,edu/
University of Minnesota:
http;//www.uky.edu/AgricuIture/FoodScience/welcome.html
University of Kentucky:
http$w3.ag.uiuc.edu/FSHN
University of Illinois:
http~/gnv.ifas.ufl.edu/www/agator/htm/foodsci.htm
University of Fiarida:
http;//www.nysaes.cornell.edu/cifs/
Cornell University:
http;lfwww.ucdavis.edu
University of California, Davis:
TN0 Nutrition and Food Research: http#.vww.tno.nl/instit/voedin&o~ext.html
USA
Tfte Netherlands
University of New South Wales: http;llwww.unsw.edu.au/clientsfoodsci/food.html
Australia
While most universities are on the Internet, some of those with food science departmentsdo not yet have home pages for, or information about, those departments. The following list is of those that do, and that are known to the author at the time of its compilation.
Box 2. University food science department home pages
Box 3.‘Sa#
different lists. The hyphens and underscore symbols (-) in some of the names are important, and must be included correctly. Any subscriber can ‘post’ a message, article, report, announcement, etc., or a response to someone else’s previous posting, by sending it by e-mail to the list address (note this is not the same as the listserver address). Every posting to the list address goes automatically by e-mail to every subscriber to the list (and cannot be cancelled after it has been sent!). You remain a subscriber until such time as you send an ‘unsubscribe’ message to the listserver address. It is very important to understand that subscribe or unsubscribe commands must not go to the list address (or they would be sent to, and annoy, all other subscribers, who anyway cannot fulfil the command). Likewise, list postings must not be sent to the listserver address, where they would just be automatically discarded by the listserver computer. The Internet is international, but the character of the material posted on mailing lists is dependent on the subscribers and the volume of ‘traffic’ that they create. For historical reasons, it will be found that in most of them (particularly those based in US universities, indicated by ‘.edu’ at the end of an address) the traffic is still predominantly US-related; however, widening the character depends on subscribers from all countries becoming involved. There are many thousands of mailing lists. There are some concerned with different foods and drinks, but not considering scientific or technological aspects. Some important ones that are related to food science and technology are listed in Box 4.
Web indexes,mvch
YahooCatalwe and database of World Wide Web sit& aisle
by &I#& M by keyw~r&s
AddfW:
http&ww.yahoo.com It&seek Database,searchable by keyword(s). Address: http#www.infoseek.com World Wide Web Virtual Library: A comprehensive cataLogw. Address: http~//wMNv.w3.0r9/hy~~e~Da~~~~~b~~~ff~ew.h~l Lycos Catatogueand database,searchableby subject or by keywordts). Address: http$lycos.cs.cmu.edu/ Web Crawler Catalogue and database,searchableby subject or by keyword(s). Address: http#webcrawler.comI The Jump Station:A software robot that searchesthe Wortd Wide Web for ~~~~e a databasethat can be searched.Address:
sites to Greate
http;l/s.stir.ac.uk&binI/js Savvy Search: An innovative keyword(s) search engine that sends your qely in parallel to man Y other sites (including Yahoo, lycos, Web Crawler] and displrtys the results in a s forma t. Address:
CDRDIS (The Community Research & Development coverage of past and present R&D projects of the Eo carries full information, and access to docur+~ in also provides instructions on accessing the d&&r& or on-line via ECHO HOST or using Watch-C~~S.~.
Address:
hnp&+ww.cordis.lu DejaNews ResearchService: A databaseof all past postings bra .yearor so&n all ,~~~r~~~. Yo U enter the complete name of the newsgroup, and can search by subject, ‘by date or by oames cIf people posting. The search brings up a tist of links; click on the one you want, and the fufL posting comes on scfeen. Address: hnp$/dejanews.com/ OKRA net citizen Directory Service: A compkzte d ha ever posted a messageon any Usenet ~~~. re! appears (or, in scrnte cases‘address&. if the person has a ~~~Y~U~Y~ addressesfor more than one person of that name. Or if a person has, over a period, had more tha one e-mail address, you will get them ali. Address: http;//wilcox.ucr.edu/okra/
Usenet newsgroups Newsgroups are Internet ‘virtual locations’ where anyone can log-on, read all or any of the messages, statements, announcements, etc. that have been previously posted, and/or respond to any of them or post a new message, announcement, etc. There are over 14 000 newsgroups, each covering a specific topic. All conceivable topics (and some barely conceivable ones) are covered. They fall into a number of main hierarchy groups, indicated by the first syllable of the name (e.g. ‘alt.’ for alternative; ‘camp.’ for computer; ‘misc.’ for miscellaneous; ‘rec.’ for recreation; and ‘sci.’ for science). Some of the newsgroups in the ‘alt.’ hierarchy Trends in Food Science & Technology January 1996 [Vol. 71
are the main homes of the much-hyped Internet pornography. To put the hype into perspective, these constitute about 50 out of the 14 000 plus newsgroups. Newsgroups are supposedly for discussion of their respective topics, but in many cases the signal-to-noise ratio is very low. Occasional nuggets are to be found but are not easy to pick out from a predominance of dross, inconsequential chitchat, peddling of unsubstantiated ‘facts’ by zealots for (or against) various causes, bigots and conspiracy theorists, abusive personal attacks (‘flaming’) and dubious advertising. To see a newsgroup, read what is posted or post to it, you need a ‘newsreader’, a piece of software that will
Box 4. Mailing lists rel&&g to food science and technology DNH-PILOT The Diet, Nutrition and Health project mailing list, covers sociology, food science and technology, agricultural economics and psychology. Researchersin academic institutions across the European Union, ideally together with industrial partners and with some external funding, are involved. Listserveraddress:dnh-pilot-requestQmaiIbase.ac.uk E-mail address:[email protected] FOOD-COMP As the name suggests,this list deals with food composition issuesand data. Listserveraddress:[email protected] E-mail address:[email protected] FOODENG A list for discussion and announcementson food engineering topics and events. Listserveraddress:[email protected] E-mail address:[email protected] FOOD-FOR-THOUGHT is a forum for discussion on all aspects of food, and a bulletin board for relevant announcements. Listserveraddress:[email protected] E-mail address:[email protected] FOOD-LAW deals with (at present, almost entirely US) existing and proposed foods laws and regulations. Listserveraddress: IistservQvml .spcs.mnu.edu E-mail address:food-IawQvml .spcs.mnu.edu
news:sci.bio.food-science
FOODLINK deals with food safety issues. Listserveraddress:[email protected] E-mail address:[email protected] FOODSCI This is a closed list, restricted to academic food science administrators (department
,chairs, heads, deans or directors); only they may subscribe (and hence receive e-mails), but anyone can post to it. It is intended to enable a single notice to be sent to all of the subscribers simultaneoysly. Listserveraddress: [email protected] E-mail address:[email protected]&u IFT This is intended for institute of Food Technologists (IFT) Food Science Communicators and other food scientists and technologists approved by the group. Its purpose is to permit very rapid dialogue on fast-breakingpublic and media issuesaffecting the food science and technology profession, Listserveraddress:[email protected] E-mail address:[email protected]
and ‘sci.med.nutrition’. As far as food science is concerned, however, in all three the signal-to-noise ratio is very low; in the first two mainly because other aspects of their subject areas heavily predominate, and in the third because the ‘sci’ is heavily outweighed by the dross already described. On 2.5 May 1995, however, the first newsgroup dealing specifically with food science and technology, called ‘sci.bio.food-science’, came into existence. Great credit is due to Rachel Beth Zemser, a postgraduate student in the Food Science Department of the University of Illinois, UrbanaChampaign, IL, USA, who took the initiative and carried out all the considerable amount of organizational work to bring it into existence, dealing with the technicalities and bureaucratic procedures required to create a new newsgroup. So far, its signalto-noise ratio has been fairly high. One way of accessing this newsgroup using Netscape is simply to type:
in the box that appears under ‘Open location’ under the ‘File’ menu. To save the location for easy future reference, go into the ‘Bookmark’ menu and select ‘Add bookmark’. The newsgroup (or any other URL stored in this way) can then be accessed simply by selection from the ‘Bookmark’ menu. As with mailing lists, newsgroups are global in scope. The character and quality of this one depends on its postings, which in turn depend on food scientists and technologists making worthwhile contributions to the discussions. It has already been attracting postings from around the world.
NUTEPIThis list deals with nutritional epidemiology. Listserveraddress:[email protected] E-mail address: NUTEPIQTUBVM.CS.TU-BERLIN.DE
usually be part of your service provider’s software package. If not, you can download the software free; an excellent one called ‘Free Agent’ is available from the Web address: http:Nwww.forteinc.com/forte There are several ‘rec.’ (recreation) newsgroups dealing with food and drink from the viewpoints of cookery, kitchen recipes, etc. In the ‘sci.’ (science) hierarchy, there are: ‘sci.bio.technology’, ‘sci.bio.microbiology’
FAQ (frequently askedquestions) Numerous sites on the Internet have their FAQ. Each is a set of answers to the most frequently asked questions on the topic with which the site is concerned. Identical sets of FAQ on food science and technology are to be found on two different sites. The IFST’s Web site: http://www.easynet.co.uMifstJ carries 51 FAQ, grouped under the main headings of ‘Food and nutrition’; ‘Food safety’; ‘Additives and packaging’; and ‘Science and food’. When the aforementioned sci.bio.food-science newsgroup was established, Trends in Food Science &Technology January 1996 [Vol. 71
the IFST’s FAQ were adopted, with permission and acknowledgement, as the FAQ for the newsgroup. The brief answers are written in popular language, to be comprehensible by non-scientists online, and to assist food scientists to respond to questions asked of them by members of the public.
ftP
Although files of ail kinds (text, graphics, software) can be transmitted from one computer to one or many others as ‘attachments’ to an e-mail, the method of downloading software from various servers around the world, where it is available free, is by ftp (‘file transfer protocol’), by either using ftp software (which is usually part of your service provider’s software package) or addressing the distant host server’s ftp address via your WWW browser.
In mid-1995, Cheesemaking in Scotland: A History, by John Smith, a now-retired dairy scientist, was published by the Scottish Dairy Association as a conventional book, but extracts were simultaneously published on the WWW, by permission of both the publisher and the author ‘for the benefit of the academic and research community’: http://www.efr.hw.ac.uMSDA/bookl.html In September 1995, R. Paul Singh, Professor of Food Engineering at the University of California, Davis, CA, USA, in addition to publishing on his home page outlines of current research projects in his department, gave the full text of one of the modules (‘Heat and mass transfer processes in food processing’) of his food engineering teaching course (for address see Box 1). He prefaced the material with the following:
‘Chat’systems
Important Copyright Information
The best-established chat system is Internet Relay Chat or IRC (with software often forming part of the service provider’s package but easily obtained free on the Internet) by which any number of persons, anywhere in the world, may take part in open, or arrange for closed, channels and take part in virtually real-time typed discussions on screen. Software is available to include voice contact (at local phone call rates!). Newer systems, accessible via the WWW, include Web Chat Broadcasting System:
I believe that creation of teaching resources, such as the material presented here, is of enormous potential for everyone on the Internet. I hope that everyone will conform to the spirit of the Internet in using the copyrighted information included here. I am pleased to grant implicit permission to the Internet community to
http:Nwww.irsociety.com/wbs.html and Powwow: http://www.tribal.comlpowwow/ The scope for prearranged discussions among geographically scattered food scientists and technologists is obvious.
Possiblefuture trends If you are a book or journal publisher, will you lose income by publishing on the WWW? And what about copyright? If you are a researcher, and citations are important to your career, will publishing on the WWW result in citations, as would result from publishing in a reputable printed journal? What would be the advantages and disadvantages of online symposia, for participants (including those who for reasons of geography, cost or time cannot attend a conventional symposium) and for organizers? Questions such as these are exercising many minds, but this is not the occasion to discuss them. It is, however, interesting to note a few sample straws in the wind. The journal Emerging Infectious Diseases: http:Nwww.cdc.gov/ncidod/EID/eid.htm is published on the Web site of the US Centers for Disease Control (http://www.cdc.gov/). The full text of any papers in current and earlier issues can be accessed and downloaded. These include important papers on foodpoisoning outbreaks and emerging foodbome pathogens. Trends in Food Science & Technology January 1996 [Vol. 71
use this information for their personal benefit in exploring the field of food engineering. However, please note that using the information included in these docu-
ments for commercial gain, or taking control of the information for reusing, reposting on the Internet, or modifying it in any way, would be detrimental to the spirit of this effort and would be a violation of the international copyright law.
Note to Instructors In future, I plan to augment these lectures with a number of photographs taken from food processing facilities around the world. These photographic slides are copyrighted and they must not be copied from these pages. Current browsers allow your students to
instantly accessthese slides for viewing purposes by connecting to this homepage. I suggest that you may want to include viewing and commenting on these slides as part of their homework assignments,I have found this method to be of considerable value in teaching at Davis. I will also hope that you will add material at your sites that will be useful in teaching food engineering. Please advise me when you have added such material so that I can ask my students to view your sites. R. Paul Singh
In preparation for the celebration, in Quebec City during October 1995, of the 50th anniversary of the foundation of the Food and Agriculture Organization of the United Nations (FAO), an interactive Internet Forum on Food Security was organized, on the FAO’s behalf, on the WWW by Lava1 University: http://FAO5O.FSAA.ULAVAL.CA/english/start.html
Kansas State University is offering five distancelearning food science and technology courses, using the Internet to deliver the course material to the students’ homes or offices:
Department’s Web (see Box 2) and linked VCCs around the world. Registration using an online form was required for access to full papers (all written in html and readable by a Web browser), mailing lists and other facilities.
http:llwww.dce.ksu.edul North Carolina State University is also developing a Master’s degree in food law (for information, send an e-mail message to: [email protected]). During September and October 1995, a comprehensive online international conference on carbohydrate and glucoconjugate chemistry was held, with abstracts of numerous papers online at the Virtual Conference Center (VCC) on Purdue University Food Science
Conclusions The foregoing outline of what already exists plus just a few pointers to the shape of things to come hold lessons for all whose work involves communication and access to information - and that includes food scientists and technologists. Just as computer literacy became vitally necessary in the 198Os, so being online and acquiring Internet and html literacy is essential now and for the future.
Review
Chlorophyll degradation in processed foods and senescent plant tissues James W. Heaton and Alejandro G. Marangoni Green colour losses in processed and minimally
processed
fruit and vegetable products are associated with decreases in the quality
of such products.
Chlorophyll,
the pigment
responsible for the characteristic green colour of several fruit and vegetables, can degrade to undesirable grey-brown compounds such as pheophorbide and pheophytin. This degradation is mediated by acid and the enzyme chlorophyllase. Pheophorbide can be further metabolized to colourless compounds in metabolically active tissue. This article summarizes the accepted mechanism of chlorophyll
degradation in fruit
and vegetables, and extends it to include the degradation of pheophorbides into colourless compounds. Strategies for the control of chlorophyll
degradation in food products are also
discussed.
lames W. Heaton and Alejandro G. Marangoni (corresponding author) are at the Department of Food Science, University of Guelph, Guelph, Ontario, Canada NlG 2Wl (fax: tl-519-824-6631; e-mail: [email protected]).
01996,
Elseviw Science Ltd
The most common change in green plants is the loss of chlorophyll. The loss of chlorophyll causes a shift in colour from brilliant green to olive brown in processed foods and to a wide variety of colours (yellow, brown, orange) in senescent tissues (Box 1). Colour changes in processed foods often represent a loss of quality, whereas colour changes of autumn leaves are desirable. Even though over lOgtonnes of chlorophyll are catabolized yearly’, its degradation pathway still remains a mystery. To understand the fate of chlorophyll in processed foods and senescent tissues, it is necessary to take a look at the changes that occur at the cellular and molecular levels. The degradation of chlorophyll in processed foods and senescent tissues will be compared in this article, in order to derive a generalized model for chlorophyll degradation. What is senescence? Senescence is best described as endogenously-controlled deteriorative changes, which are natural causes of death in cells, tissues, organs or organisms*. The key points in this definition are that changes taking place at the microscopic level affect the whole organism, and that the changes seem to be regulated internally by the cell and not by the environment. Although environmental factors may trigger senescence or enhance it, it is imperative to understand that environmental factors do not regulate it. This is different, however, from the situation in processed foods, where both the environment and the cell regulate chlorophyll catabolism. As will become apparent, ingredients in processed foods and processing conditions greatly influence the pathway of chlorophyll destruction. Chloroplastic changes During senescence, large structural changes are readily observed in the chloroplast. The first noticeable Trends in Food Science & Technology
January 1996 [Vol. 71
Food science and The Internet, in its various manifestations, is rapidly becoming both a major means of communication
and an indispensable
information tool for those who know how to use it. In the 199Os, with the advent of the Internet’s rapidly expanding user-friendly interface, the World Wide Web, knowing how to use it has spread far beyond computer experts skilled in a
technology on the Internet*
range of arcane techniques, to virtually anyone with a subscription to a service provider and a PC (or any other computer type) fitted with a modem linked to a telephone line.
J. Ralph Blanchfield
Across the world, government departments, international and national institutions, universities, banks, companies and individuals are either already ‘on the Net’ or hurrying to get on. The already substantial opportunities both to acquire and to communicate food science and technology information may be expected to proliferate and expand as fast as the Internet itself.
Nobody ‘owns’ the Internet, nobody controls it. It is a worldwide anarchic network of computer networks linked via the telephone system in such a way that if any of them is out of action, communications find a route through the rest of the network. It is a means of interrogating computers and databases throughout the world (e.g. of libraries, universities, research institutions, govemment organizations and agencies, and commercial organizations that have chosen to act as ‘servers’) and acquiring or conveying data, text and computer files of all kinds. (Note: being on the Internet does not mean that one’s own computer is open to entry or interrogation, unless one wishes that to take place.) Information is transferred by a common protocol that is recognized and actioned by any computer in, or linked to, the network, regardless of its make or its operating system. The Internet’s origin is traceable back to the 1960s when the US Defense Department established ARPANET (Advanced Research Projects Agency Network), a computer network that would continue to maintain communications even if part of it was destroyed by nuclear attack. During the 1970s and 198Os, academic institutions in the USA established a computer network that became linked into ARPANET. Then the US National Science Foundation established a network. which was initially linked to ARPANET. but subsequently operated separately as NSFNET. Around 1990 it was opened to general use, and became recognized as the Internet. Around 1990, at the European Particle Physics
*Readers should be aware that there are aspects of e-mail security, such as viruses on imported programs and ‘hacking’. These are subjects too wide to address in this article. J. Ralph Blanchfield is at 17 Arabia Close, Chingford, London, UK E4 7DU itel: +44-81-524-1800; e-mail: [email protected].
Trends in
Food Science & Technology
January
1996 [Vol. 71
Laboratory (CERN, in Geneva, Switzerland) the World Wide Web (WWW) was originated as a user-friendly interface with the Internet, and was developed into a publicly usable system by March 1993, initiating evolution at an escalating rate amounting to revolution. It is because of its history that, until very recently, the Internet developed almost entirely as a US phenomenon, with a US ‘culture’. Likewise, US users have a longer-established culture of using the Internet, and still make up the majority of users (75% according to the most recent survey). However, this situation is rapidly changing, especially since the advent of the WWW.
The Internet One way of describing the Internet is in terms of its facilities. These are numerous, but for the purposes of this article the most important are: electronic mail (e-mail for short); the WWW; indexes, search engines and databases; mailing lists; newsgroups; ftp (‘file transfer protocol’); and ‘chat’ systems. Use of any of these facilities involves a modem link with your service provider’s server computer (or your computer may already have a direct link via your employer’s or university’s local network); and if your service provider is in your local telephone area, no matter where in the world your communications are going to or coming from, all your online phone time is at local call rates.
E-mail E-mail software usually forms part of the package you receive from your service provider. It is a means of communicating with one recipient, or simultaneously with any number. It is faster to send an e-mail message than an equivalent fax, and it is charged at local phone call rates. However, although it is faster and cheaper to do the sending, the time it takes for the message to be received depends on the routing of the message, which eventually reaches the recipient after being passed on by many intermediary machines (this can take many hours, and is not controlled by the sender), and also requires recipients to log onto their computers regularly. E-mail is also the means of posting messages to, and receiving them from, mailing lists (see below). 01996,
Elsevier Science Ltd
The use of html permits certain words or phrases (or graphics), designed to be ‘hot spots’, to stand out (e.g. in a different colour and/or underlined) from the rest; thus, when the cursor is placed on one such hot spot, and the computer mouse is clicked, it automatically takes the reader to another page to which the word or phrase refers. A single page may contain numerous links, which readers may follow (or not) as the fancy takes them. Navigating a Web site is therefore nothing like reading the pages of a book in sequence. Moreover, unlike a paper page, a ‘page’ on the WWW is of no fixed size; it corresponds to a computer file and is as short or as long as c!DOClYPE HTML SYSTEM “html.dtd”>cHTML>
Welcome to very long pages. the Home Page of the Institute of Food Science & Technology, more familiarly known as In every field of activity and interIFST.~H~XP> eH3>cB4FST is the independent incorporated professionalc/As qualifying body for food scientists and available on the WWW. There are ,technologists. Its purposes are :-~BxIH~~~P%UL>~LI>to serve the also numerous organizations of all public interestc/Az by furthering the application of science and kinds (and even individuals) with technology to all aspects of the supply of safe, wholesome, nutritious and attractive food, home pages, with hundreds more nationally and internationally;cLl>to advance the standing of CA being added and announced every HREF=“fst. htm”>food science and technology
, both as a subject and as a day. In most cases, the home page will profession;cP>cLlsto assist members in their career and contain a number of hypertext hotpersonal developmentc/A> within the profession;cP>2
Trends in Food Science & Technology January 1996 [Vol. 71
that the URLs of the main university, government or company computers change less often than the URLs of specific subdirectories, such as a given department or database address, which may be reorganized periodically. So, if you consistently find that you cannot access a given site, try typing in only the beginning of the address, ending after the country or main network code (e.g. ‘.com’, ‘.edu’, ‘.uk’, ‘.au’ or ‘.ca’), possibly followed by a slash (/) mark. This should get you to the site’s main computer; you can then look for the updated links to the relevant department.
Weave your own Web For those accustomed to using ‘Windows’ and word processors, writing html files with the aid of an html text editor (software acquired free by downloading from the Internet) is a skill very quickly and easily acquired from any of the numerous books, Internet magazines (such as Internet, Internet Today, NetUser and .net, all available in newsagents), or articles on the WWW itself - there are several useful links, including one to an interactive tutorial, on Netscape’s own page: http://home.netscape.com/assist/net_sites/index.html Good layout and graphic design of Web pages, which involve different criteria, and have to be achieved by different methods from on-paper design, are another matter and outside the scope of this article. Having a home page does not mean that your computer has to remain online or that those accessing it can ‘invade’ your computer; your home page is maintained (for an annual fee) in the computer of your service provider. You can modify and update your own page(s) but others accessing it cannot. You can, however, provide interactive pages through which a reader can send you feedback.
Web indexes,search engines,special subject databases Web indexes, which are updated with thousands of new entries daily, cover all topics in main categories and several levels of sub-categories, each topic and subtopic name being a hypertext link, so that you can narrow down your topic to a list from which you select the item you want and bring it up on screen. Increasingly, however, these indexes provide an alternative option that allows them to be interrogated as databases using keyword(s). Search engines operate wholly as such databases. See Box 3 for further information.
Mailing lists (‘listservs’) An Internet mailing list is maintained on a ‘listserver’ computer, and you join it (at no cost) by sending a ‘subscribe’ message plus the name of the list and your first and last names, by e-mail to the listserver address, which is the address of the computer that ‘manages’ the list. For example, should 1 wish to join the FOOD-LAW list, I would send an e-mail to the listserver address ([email protected]). I would type: subscribe FOOD-LAW
Ralph Blanchfield
as the body of my message. Inclusion of the name of the list is important as some listservers run a number of Trends in Food Science & Technology January 1996 [Vol. 71
fi.ilniul
ark -* .~ Royal Veterinary & Agricultural University: hu&fwww.fc tici.kvl.dk
http~/~.tuns.ca:8O/foodscif
Technical University of Nova Scotia:
http;//www.umanitoba.c~AgricuIture/Agriculture.html
University of Manitoba:
http#www.fo&ci.uoguetph.ca
University of Guelph:
httpY/www.afns.ualberta.ca
University of Alberta:
N~ingham University:
h~~~~.unl.ac.~k:8~lc~e.h~ml
University of North London:
~~/~.doc.mmu.at.uWhoiACi/courses.html
Manchester Metropolitan University:
https’fwww.food.leeds.ac.uk/food.htm
University of Leeds:
hhttpz//www.fen.bris.ac.uk/mech/frperc/frperc.htm
University of Bristol (Food Refrigeration and Process Engineering ResearchCentre):
UK
http;//www.kc.lu.se/inl/
Lund University:
Acadia University:
http#ace.acadiau.ca/science/nutr/home.html
Sweden
Canada
http;l/www.massey.ac.nz/-wwtech/old/TechnologyHome.html
University of QueensJand:
httpi/www.uq.oz.au/fst/
New Zealand Massey University:
http$vww.spb.wau,nl/lmt/
Wageningen Agricultural University:
5opher~/gopher.acs.ohio-state.edu:70/00/OSU%20Colleges% 20and%ZQDi3partment~/OfficeY~2O~f~~2DAdmission~%2~a~d %2~Fina~ciat%2OA~d/Admissions%2~lnformatjon% 20-%200hio%20StatelUnderg~aduate”~20tnformat~on% ZO-%20 Ohio %20 State/maiors/fdx
Ohio State University:
http#www2.ncsu.edu/ncsu/caIs/food-science/indexexhtml
North Carolina State University:
http#anrwww.unl.edu/ianr/foodsci/fstfpc.htm
University of Nebraska:
http-//www.fsci.umn,edu/
University of Minnesota:
http;//www.uky.edu/AgricuIture/FoodScience/welcome.html
University of Kentucky:
http$w3.ag.uiuc.edu/FSHN
University of Illinois:
http~/gnv.ifas.ufl.edu/www/agator/htm/foodsci.htm
University of Fiarida:
http;//www.nysaes.cornell.edu/cifs/
Cornell University:
http;lfwww.ucdavis.edu
University of California, Davis:
TN0 Nutrition and Food Research: http#.vww.tno.nl/instit/voedin&o~ext.html
USA
Tfte Netherlands
University of New South Wales: http;llwww.unsw.edu.au/clientsfoodsci/food.html
Australia
While most universities are on the Internet, some of those with food science departmentsdo not yet have home pages for, or information about, those departments. The following list is of those that do, and that are known to the author at the time of its compilation.
Box 2. University food science department home pages
Box 3.‘Sa#
different lists. The hyphens and underscore symbols (-) in some of the names are important, and must be included correctly. Any subscriber can ‘post’ a message, article, report, announcement, etc., or a response to someone else’s previous posting, by sending it by e-mail to the list address (note this is not the same as the listserver address). Every posting to the list address goes automatically by e-mail to every subscriber to the list (and cannot be cancelled after it has been sent!). You remain a subscriber until such time as you send an ‘unsubscribe’ message to the listserver address. It is very important to understand that subscribe or unsubscribe commands must not go to the list address (or they would be sent to, and annoy, all other subscribers, who anyway cannot fulfil the command). Likewise, list postings must not be sent to the listserver address, where they would just be automatically discarded by the listserver computer. The Internet is international, but the character of the material posted on mailing lists is dependent on the subscribers and the volume of ‘traffic’ that they create. For historical reasons, it will be found that in most of them (particularly those based in US universities, indicated by ‘.edu’ at the end of an address) the traffic is still predominantly US-related; however, widening the character depends on subscribers from all countries becoming involved. There are many thousands of mailing lists. There are some concerned with different foods and drinks, but not considering scientific or technological aspects. Some important ones that are related to food science and technology are listed in Box 4.
Web indexes,mvch
YahooCatalwe and database of World Wide Web sit& aisle
by &I#& M by keyw~r&s
AddfW:
http&ww.yahoo.com It&seek Database,searchable by keyword(s). Address: http#www.infoseek.com World Wide Web Virtual Library: A comprehensive cataLogw. Address: http~//wMNv.w3.0r9/hy~~e~Da~~~~~b~~~ff~ew.h~l Lycos Catatogueand database,searchableby subject or by keywordts). Address: http$lycos.cs.cmu.edu/ Web Crawler Catalogue and database,searchableby subject or by keyword(s). Address: http#webcrawler.comI The Jump Station:A software robot that searchesthe Wortd Wide Web for ~~~~e a databasethat can be searched.Address:
sites to Greate
http;l/s.stir.ac.uk&binI/js Savvy Search: An innovative keyword(s) search engine that sends your qely in parallel to man Y other sites (including Yahoo, lycos, Web Crawler] and displrtys the results in a s forma t. Address:
CDRDIS (The Community Research & Development coverage of past and present R&D projects of the Eo carries full information, and access to docur+~ in also provides instructions on accessing the d&&r& or on-line via ECHO HOST or using Watch-C~~S.~.
Address:
hnp&+ww.cordis.lu DejaNews ResearchService: A databaseof all past postings bra .yearor so&n all ,~~~r~~~. Yo U enter the complete name of the newsgroup, and can search by subject, ‘by date or by oames cIf people posting. The search brings up a tist of links; click on the one you want, and the fufL posting comes on scfeen. Address: hnp$/dejanews.com/ OKRA net citizen Directory Service: A compkzte d ha ever posted a messageon any Usenet ~~~. re! appears (or, in scrnte cases‘address&. if the person has a ~~~Y~U~Y~ addressesfor more than one person of that name. Or if a person has, over a period, had more tha one e-mail address, you will get them ali. Address: http;//wilcox.ucr.edu/okra/
Usenet newsgroups Newsgroups are Internet ‘virtual locations’ where anyone can log-on, read all or any of the messages, statements, announcements, etc. that have been previously posted, and/or respond to any of them or post a new message, announcement, etc. There are over 14 000 newsgroups, each covering a specific topic. All conceivable topics (and some barely conceivable ones) are covered. They fall into a number of main hierarchy groups, indicated by the first syllable of the name (e.g. ‘alt.’ for alternative; ‘camp.’ for computer; ‘misc.’ for miscellaneous; ‘rec.’ for recreation; and ‘sci.’ for science). Some of the newsgroups in the ‘alt.’ hierarchy Trends in Food Science & Technology January 1996 [Vol. 71
are the main homes of the much-hyped Internet pornography. To put the hype into perspective, these constitute about 50 out of the 14 000 plus newsgroups. Newsgroups are supposedly for discussion of their respective topics, but in many cases the signal-to-noise ratio is very low. Occasional nuggets are to be found but are not easy to pick out from a predominance of dross, inconsequential chitchat, peddling of unsubstantiated ‘facts’ by zealots for (or against) various causes, bigots and conspiracy theorists, abusive personal attacks (‘flaming’) and dubious advertising. To see a newsgroup, read what is posted or post to it, you need a ‘newsreader’, a piece of software that will
Box 4. Mailing lists rel&&g to food science and technology DNH-PILOT The Diet, Nutrition and Health project mailing list, covers sociology, food science and technology, agricultural economics and psychology. Researchersin academic institutions across the European Union, ideally together with industrial partners and with some external funding, are involved. Listserveraddress:dnh-pilot-requestQmaiIbase.ac.uk E-mail address:[email protected] FOOD-COMP As the name suggests,this list deals with food composition issuesand data. Listserveraddress:[email protected] E-mail address:[email protected] FOODENG A list for discussion and announcementson food engineering topics and events. Listserveraddress:[email protected] E-mail address:[email protected] FOOD-FOR-THOUGHT is a forum for discussion on all aspects of food, and a bulletin board for relevant announcements. Listserveraddress:[email protected] E-mail address:[email protected] FOOD-LAW deals with (at present, almost entirely US) existing and proposed foods laws and regulations. Listserveraddress: IistservQvml .spcs.mnu.edu E-mail address:food-IawQvml .spcs.mnu.edu
news:sci.bio.food-science
FOODLINK deals with food safety issues. Listserveraddress:[email protected] E-mail address:[email protected] FOODSCI This is a closed list, restricted to academic food science administrators (department
,chairs, heads, deans or directors); only they may subscribe (and hence receive e-mails), but anyone can post to it. It is intended to enable a single notice to be sent to all of the subscribers simultaneoysly. Listserveraddress: [email protected] E-mail address:[email protected]&u IFT This is intended for institute of Food Technologists (IFT) Food Science Communicators and other food scientists and technologists approved by the group. Its purpose is to permit very rapid dialogue on fast-breakingpublic and media issuesaffecting the food science and technology profession, Listserveraddress:[email protected] E-mail address:[email protected]
and ‘sci.med.nutrition’. As far as food science is concerned, however, in all three the signal-to-noise ratio is very low; in the first two mainly because other aspects of their subject areas heavily predominate, and in the third because the ‘sci’ is heavily outweighed by the dross already described. On 2.5 May 1995, however, the first newsgroup dealing specifically with food science and technology, called ‘sci.bio.food-science’, came into existence. Great credit is due to Rachel Beth Zemser, a postgraduate student in the Food Science Department of the University of Illinois, UrbanaChampaign, IL, USA, who took the initiative and carried out all the considerable amount of organizational work to bring it into existence, dealing with the technicalities and bureaucratic procedures required to create a new newsgroup. So far, its signalto-noise ratio has been fairly high. One way of accessing this newsgroup using Netscape is simply to type:
in the box that appears under ‘Open location’ under the ‘File’ menu. To save the location for easy future reference, go into the ‘Bookmark’ menu and select ‘Add bookmark’. The newsgroup (or any other URL stored in this way) can then be accessed simply by selection from the ‘Bookmark’ menu. As with mailing lists, newsgroups are global in scope. The character and quality of this one depends on its postings, which in turn depend on food scientists and technologists making worthwhile contributions to the discussions. It has already been attracting postings from around the world.
NUTEPIThis list deals with nutritional epidemiology. Listserveraddress:[email protected] E-mail address: NUTEPIQTUBVM.CS.TU-BERLIN.DE
usually be part of your service provider’s software package. If not, you can download the software free; an excellent one called ‘Free Agent’ is available from the Web address: http:Nwww.forteinc.com/forte There are several ‘rec.’ (recreation) newsgroups dealing with food and drink from the viewpoints of cookery, kitchen recipes, etc. In the ‘sci.’ (science) hierarchy, there are: ‘sci.bio.technology’, ‘sci.bio.microbiology’
FAQ (frequently askedquestions) Numerous sites on the Internet have their FAQ. Each is a set of answers to the most frequently asked questions on the topic with which the site is concerned. Identical sets of FAQ on food science and technology are to be found on two different sites. The IFST’s Web site: http://www.easynet.co.uMifstJ carries 51 FAQ, grouped under the main headings of ‘Food and nutrition’; ‘Food safety’; ‘Additives and packaging’; and ‘Science and food’. When the aforementioned sci.bio.food-science newsgroup was established, Trends in Food Science &Technology January 1996 [Vol. 71
the IFST’s FAQ were adopted, with permission and acknowledgement, as the FAQ for the newsgroup. The brief answers are written in popular language, to be comprehensible by non-scientists online, and to assist food scientists to respond to questions asked of them by members of the public.
ftP
Although files of ail kinds (text, graphics, software) can be transmitted from one computer to one or many others as ‘attachments’ to an e-mail, the method of downloading software from various servers around the world, where it is available free, is by ftp (‘file transfer protocol’), by either using ftp software (which is usually part of your service provider’s software package) or addressing the distant host server’s ftp address via your WWW browser.
In mid-1995, Cheesemaking in Scotland: A History, by John Smith, a now-retired dairy scientist, was published by the Scottish Dairy Association as a conventional book, but extracts were simultaneously published on the WWW, by permission of both the publisher and the author ‘for the benefit of the academic and research community’: http://www.efr.hw.ac.uMSDA/bookl.html In September 1995, R. Paul Singh, Professor of Food Engineering at the University of California, Davis, CA, USA, in addition to publishing on his home page outlines of current research projects in his department, gave the full text of one of the modules (‘Heat and mass transfer processes in food processing’) of his food engineering teaching course (for address see Box 1). He prefaced the material with the following:
‘Chat’systems
Important Copyright Information
The best-established chat system is Internet Relay Chat or IRC (with software often forming part of the service provider’s package but easily obtained free on the Internet) by which any number of persons, anywhere in the world, may take part in open, or arrange for closed, channels and take part in virtually real-time typed discussions on screen. Software is available to include voice contact (at local phone call rates!). Newer systems, accessible via the WWW, include Web Chat Broadcasting System:
I believe that creation of teaching resources, such as the material presented here, is of enormous potential for everyone on the Internet. I hope that everyone will conform to the spirit of the Internet in using the copyrighted information included here. I am pleased to grant implicit permission to the Internet community to
http:Nwww.irsociety.com/wbs.html and Powwow: http://www.tribal.comlpowwow/ The scope for prearranged discussions among geographically scattered food scientists and technologists is obvious.
Possiblefuture trends If you are a book or journal publisher, will you lose income by publishing on the WWW? And what about copyright? If you are a researcher, and citations are important to your career, will publishing on the WWW result in citations, as would result from publishing in a reputable printed journal? What would be the advantages and disadvantages of online symposia, for participants (including those who for reasons of geography, cost or time cannot attend a conventional symposium) and for organizers? Questions such as these are exercising many minds, but this is not the occasion to discuss them. It is, however, interesting to note a few sample straws in the wind. The journal Emerging Infectious Diseases: http:Nwww.cdc.gov/ncidod/EID/eid.htm is published on the Web site of the US Centers for Disease Control (http://www.cdc.gov/). The full text of any papers in current and earlier issues can be accessed and downloaded. These include important papers on foodpoisoning outbreaks and emerging foodbome pathogens. Trends in Food Science & Technology January 1996 [Vol. 71
use this information for their personal benefit in exploring the field of food engineering. However, please note that using the information included in these docu-
ments for commercial gain, or taking control of the information for reusing, reposting on the Internet, or modifying it in any way, would be detrimental to the spirit of this effort and would be a violation of the international copyright law.
Note to Instructors In future, I plan to augment these lectures with a number of photographs taken from food processing facilities around the world. These photographic slides are copyrighted and they must not be copied from these pages. Current browsers allow your students to
instantly accessthese slides for viewing purposes by connecting to this homepage. I suggest that you may want to include viewing and commenting on these slides as part of their homework assignments,I have found this method to be of considerable value in teaching at Davis. I will also hope that you will add material at your sites that will be useful in teaching food engineering. Please advise me when you have added such material so that I can ask my students to view your sites. R. Paul Singh
In preparation for the celebration, in Quebec City during October 1995, of the 50th anniversary of the foundation of the Food and Agriculture Organization of the United Nations (FAO), an interactive Internet Forum on Food Security was organized, on the FAO’s behalf, on the WWW by Lava1 University: http://FAO5O.FSAA.ULAVAL.CA/english/start.html
Kansas State University is offering five distancelearning food science and technology courses, using the Internet to deliver the course material to the students’ homes or offices:
Department’s Web (see Box 2) and linked VCCs around the world. Registration using an online form was required for access to full papers (all written in html and readable by a Web browser), mailing lists and other facilities.
http:llwww.dce.ksu.edul North Carolina State University is also developing a Master’s degree in food law (for information, send an e-mail message to: [email protected]). During September and October 1995, a comprehensive online international conference on carbohydrate and glucoconjugate chemistry was held, with abstracts of numerous papers online at the Virtual Conference Center (VCC) on Purdue University Food Science
Conclusions The foregoing outline of what already exists plus just a few pointers to the shape of things to come hold lessons for all whose work involves communication and access to information - and that includes food scientists and technologists. Just as computer literacy became vitally necessary in the 198Os, so being online and acquiring Internet and html literacy is essential now and for the future.
Review
Chlorophyll degradation in processed foods and senescent plant tissues James W. Heaton and Alejandro G. Marangoni Green colour losses in processed and minimally
processed
fruit and vegetable products are associated with decreases in the quality
of such products.
Chlorophyll,
the pigment
responsible for the characteristic green colour of several fruit and vegetables, can degrade to undesirable grey-brown compounds such as pheophorbide and pheophytin. This degradation is mediated by acid and the enzyme chlorophyllase. Pheophorbide can be further metabolized to colourless compounds in metabolically active tissue. This article summarizes the accepted mechanism of chlorophyll
degradation in fruit
and vegetables, and extends it to include the degradation of pheophorbides into colourless compounds. Strategies for the control of chlorophyll
degradation in food products are also
discussed.
lames W. Heaton and Alejandro G. Marangoni (corresponding author) are at the Department of Food Science, University of Guelph, Guelph, Ontario, Canada NlG 2Wl (fax: tl-519-824-6631; e-mail: [email protected]).
01996,
Elseviw Science Ltd
The most common change in green plants is the loss of chlorophyll. The loss of chlorophyll causes a shift in colour from brilliant green to olive brown in processed foods and to a wide variety of colours (yellow, brown, orange) in senescent tissues (Box 1). Colour changes in processed foods often represent a loss of quality, whereas colour changes of autumn leaves are desirable. Even though over lOgtonnes of chlorophyll are catabolized yearly’, its degradation pathway still remains a mystery. To understand the fate of chlorophyll in processed foods and senescent tissues, it is necessary to take a look at the changes that occur at the cellular and molecular levels. The degradation of chlorophyll in processed foods and senescent tissues will be compared in this article, in order to derive a generalized model for chlorophyll degradation. What is senescence? Senescence is best described as endogenously-controlled deteriorative changes, which are natural causes of death in cells, tissues, organs or organisms*. The key points in this definition are that changes taking place at the microscopic level affect the whole organism, and that the changes seem to be regulated internally by the cell and not by the environment. Although environmental factors may trigger senescence or enhance it, it is imperative to understand that environmental factors do not regulate it. This is different, however, from the situation in processed foods, where both the environment and the cell regulate chlorophyll catabolism. As will become apparent, ingredients in processed foods and processing conditions greatly influence the pathway of chlorophyll destruction. Chloroplastic changes During senescence, large structural changes are readily observed in the chloroplast. The first noticeable Trends in Food Science & Technology
January 1996 [Vol. 71