tag:theconversation.com,2011:/global/topics/canning-19536/articlesCanning – The Conversation2016-09-15T10:51:56Ztag:theconversation.com,2011:article/643182016-09-15T10:51:56Z2016-09-15T10:51:56ZHere’s the clever chemistry that can stop your food rotting<figure><img src="https://images.theconversation.com/files/137783/original/image-20160914-4989-jrve94.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">All things must die. But when?</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-171293201/stock-photo-green-and-rotten-isolated-object-element-of-design.html?src=ovyhEhsrvj86cyOI0fmtUQ-1-62">Shutterstock</a></span></figcaption></figure><p>A hotel in Reykjavík has on display a McDonald’s burger and fries, seemingly undecomposed after 2,512 days – and counting. It was bought on October 30, 2009, the day that the last McDonald’s in Iceland <a href="http://news.bbc.co.uk/1/hi/8327185.stm">closed</a>. But you don’t have to go to Reykjavík to see it: it has its <a href="http://bushostelreykjavik.com/last-mcdonalds-in-iceland">own webcam so you can watch it from your armchair</a>.</p>
<p>What makes this meal so long-lived? Well, I haven’t examined this particular burger myself, but chemical reactions cause food to decay – and understanding them can help us to keep food better and for longer.</p>
<p>Let’s start with uncooked rice – in many peoples’ minds it’s a foodstuff that will keep for a long while. Experts reckon that <a href="http://www.thefreedictionary.com/polished+rice">polished white rice</a> will keep for 30 years when properly sealed and stored in a cool, dry place. This means in an airtight container with oxygen absorbers that remove the gas that can oxidise molecules in the rice.</p>
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<p>Hotter food goes off faster; as you may remember from school science lessons, chemical reactions are faster at high temperatures because hotter molecules have more energy and so are more likely to react when they collide. It’s one reason we have fridges. But there is a limit. Above a certain temperature (approximately 50-100°C), the enzymes in a bacterium get denatured – their “active site”, where its catalytic activity happens and it binds to molecules to carry out reactions on them, loses its shape and can no longer carry out reactions. </p>
<p>Back in the 19th century, <a href="http://www.bbc.co.uk/timelines/z9kj2hv">Louis Pasteur</a> invented the process that bears his name. <a href="http://www.dairycouncil.co.uk/consumers/industry/what-is-pasteurisation">Pasteurisation</a> kills the bacteria that make food go off and today this is applied mainly to milk. Milk that has been pasteurised by heating to just over 70°C will keep for two to three weeks when refrigerated, while UHT milk, made by heating to 140°C, will keep in airtight, sterile containers for up to nine months. Raw milk left in the fridge would <a href="http://www.raw-milk-facts.com/Raw_Milk_FAQ.html">last only a few days</a>. </p>
<h2>Living off the land</h2>
<p>The short life of food was the reason that medieval armies “lived off the land” by scavenging, but in 1809 a Frenchman named <a href="https://www.britannica.com/biography/Nicolas-Appert">Nicholas Appert</a> won a prize offered by his government for a process for preserving food. He showed that food sealed inside a container to exclude air and then cooked to a high enough temperature to kill microbes such as <em>Clostridium botulinum</em> kept for a long time. </p>
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<img alt="" src="https://images.theconversation.com/files/137908/original/image-20160915-30587-1idxx66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/137908/original/image-20160915-30587-1idxx66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/137908/original/image-20160915-30587-1idxx66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/137908/original/image-20160915-30587-1idxx66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/137908/original/image-20160915-30587-1idxx66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/137908/original/image-20160915-30587-1idxx66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/137908/original/image-20160915-30587-1idxx66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Clostridium botulinum bacteria.</span>
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<p>He’d invented <a href="https://kayjayaitch.wordpress.com/2016/04/15/the-truth-about-canning/">canning</a>, which came into widespread use, and not just for feeding armies and expeditions – it was immediately taken up by the civilian sector, too. <a href="http://www.emeraldinsight.com/doi/pdfplus/10.1108/eb011318">Tinned food certainly works</a>. Sir William Edward Parry, for example, took 26 tons of canned pea soup, beef and mutton with him in 1824 on his expedition to find the Northwest Passage. One of these mutton cans was opened in <a href="http://alanskitchen.com/Food_Preservation/Canning/0001-0025/0001-Canning_History.htm">1939 and found to be edible, if not very palatable</a>. </p>
<p>Conversely, cold slows germ growth. Keeping food at around 5°C in a fridge slows microbial growth – but it doesn’t stop it. People living in very cold areas like the Arctic discovered this sooner, of course, without the need for fridges. And watching the Inuit fish under thick ice gave <a href="http://www.biography.com/people/clarence-birdseye-9213147">Clarence Birdseye</a> the idea of fast-freezing food; this creates smaller ice crystals than ordinary freezing, resulting in less damage to cell walls, so the food not only keeps for longer but also tastes better.</p>
<h2>Sugar and spice and all things nice</h2>
<p>Beginning with communities in hotter regions like the Middle East, dried food has been around for thousands of years – the earliest cases are thought to date back to 12,000BC. Drying food, whether using the sun (and wind) or modern factory processes, removes water from the cells of the microbes that break down food. This stops them reproducing and ultimately kills them.</p>
<p>An extension of this is the use of salt (or sugar) to preserve food. While salt beef and pork may conjure up thoughts of the Royal Navy in the days of <a href="https://savoringthepast.net/2013/01/08/salted-meat-for-a-journey-at-sea/">Jack Aubrey and Stephen Maturin</a> – heroes of Patrick O'Brian’s Napoleonic novels – the process goes back much further than that.</p>
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<figcaption><span class="caption">Master and Commander: Aubrey and Maturin.</span></figcaption>
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<p>In the Middle Ages, salted fish like herring and cod were widely eaten in northern Europe, and fish was of course essential during Lent. The cells of microorganisms have walls that are <a href="http://www.scienceclarified.com/everyday/Real-Life-Chemistry-Vol-2/Osmosis-Real-life-applications.html">permeable to water but not to salt</a>. When the cell is in contact with salt, osmosis takes place, so water moves out of the cell in order to try to equalise the salt concentration inside and outside the cell, and eventually so much water is removed from the cell that it dies. No more bacteria.</p>
<p><a href="http://www.scientificamerican.com/article/how-do-salt-and-sugar-pre/">Sugar</a> has a similar effect, just think of fruit preserves, jam or jellies. Smoking also dries out food. Some of the molecules formed when wood is burned, <a href="https://podfanatic.com/podcast/chemistry-in-its-element/episode/vanillin-chemistry-in-its-element-1">like vanillin</a>, will add flavour, while others, including formaldehyde and organic acids have preservative properties.</p>
<p>Freeze-drying is an up-to-date way of removing water from food, perhaps this is the kind of coffee that you use. Modern manufacturers are tapping into something that the Incas in the High Andes developed 2,000 years ago to prepare freeze-dried potatoes, <a href="http://photos.oregonlive.com/photo-essay/2013/08/method_of_freeze-drying_potato.html">known as chuño</a>. The practice continues today. Potatoes are left out overnight, when freezing temperatures are guaranteed, then they trample on them, bare-footed, to mash them up. The blistering sun then completes the job – you have a food that will keep for months, food either for the Inca armies or the peasants of Bolivia and Peru.</p>
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<img alt="" src="https://images.theconversation.com/files/137907/original/image-20160915-30605-11qjxjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/137907/original/image-20160915-30605-11qjxjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=406&fit=crop&dpr=1 600w, https://images.theconversation.com/files/137907/original/image-20160915-30605-11qjxjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=406&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/137907/original/image-20160915-30605-11qjxjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=406&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/137907/original/image-20160915-30605-11qjxjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=510&fit=crop&dpr=1 754w, https://images.theconversation.com/files/137907/original/image-20160915-30605-11qjxjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=510&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/137907/original/image-20160915-30605-11qjxjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=510&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Turmeric: hidden powers.</span>
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<p>How about spices? Well, <a href="http://theplate.nationalgeographic.com/2014/12/01/stinky-smelly-wonderful-onions/">both onion and garlic have antimicrobial properties</a>. There is <a href="https://blogs.cornell.edu/cibt/files/2015/05/Antimicrobial-Functions-of-Spices.pdf">evidence</a> that the use of spices in warmer climates is linked with their <a href="http://news.nationalgeographic.com/news/2005/11/1111_051111_spicy_medicine.html">antimicrobial properties</a>, so adding them to food can help preserve it.</p>
<p>The antibacterial activity of some spices, notably cinnamon and coriander, is probably due to the <a href="https://www.chemistryworld.com/podcasts/hexenal/6836.article">aldehydes</a> – reactive molecules containing a –CHO group, formed by oxidising alcohols and including hexenal, the molecule we smell when grass is freshly cut – <a href="http://www.academicjournals.org/article/article1380527716_Joe%20et%20al.pdf">they contain</a>. </p>
<p>The spice that has got most attention is turmeric, made from the roots of a plant in the ginger family, <em>Curcuma longa</em>, and particularly a molecule it contains, called <a href="http://www.ncbi.nlm.nih.gov/pubmed/26652155">curcumin</a>. Turmeric was used in food in the Indus valley over 4,000 years ago, as well as in medicine. Today, it may be a useful lead molecule against <a href="http://news.vanderbilt.edu/2015/01/curcumin%E2%80%99s-ability-to-fight-alzheimer-studied/">Alzheimer’s disease</a>, as well as possibly interfering with various signalling pathways implicated in cancers.</p>
<p>So there is sound science behind the processes used to preserve food and some of these substances <a href="http://www.ccsenet.org/journal/index.php/jfr/article/download/26027/17077">may have hidden benefits to our health</a>. That hamburger in Iceland, however, remains a mystery. There certainly have been plenty of media stories trying to get the <a href="http://www.businessinsider.com.au/myth-mcdonalds-burgers-dont-rot-2012-10?_ga=1.255710472.1434746596.1397489641">bottom of its apparent immortality</a> – but the only way to be sure would be to subject it to rigorous scientific enquiry. Perhaps I’ll book my flight.</p><img src="https://counter.theconversation.com/content/64318/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Cotton does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Anyone for a 2,512-day-old burger?Simon Cotton, Senior Lecturer in Chemistry, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/462862015-08-18T12:38:21Z2015-08-18T12:38:21ZThe voters of Canning could have quite a say on Tony Abbott’s leadership<p>So once again Tony Abbott has told the Coalition partyroom that he’s ticked off his cabinet ministers. Read them the riot act, he said.</p>
<p>They seem to be slow learners, those ministers. Or, more to the point, some of them are increasingly angry with their leader. It was only June when Abbott lectured them about leaking and <a href="https://theconversation.com/oh-lordy-what-a-sight-a-cabinet-room-come-to-jesus-moment-42690">said later</a> there had been a “come to Jesus moment” in cabinet. The moment quickly passed, apparently.</p>
<p>Abbott now is frustrated by both leaks and ministers speaking out publicly about the way forward on same-sex marriage. But at Monday’s cabinet meeting he failed to finalise a process, beyond confirming the popular vote would be next term, not before.</p>
<p>Crucially, there is no decision on whether that vote would be a plebiscite or referendum. Abbott is bringing something back to cabinet and the party room. The majority thinking in cabinet seems for a plebiscite; if he proposed a referendum, he might need to get out the tear gas.</p>
<p>Amid reports of leadership chatter – going nowhere at the moment – a <a href="https://theconversation.com/heydons-email-trail-for-barwick-dinner-made-its-liberal-connections-clear-from-the-start-46211">serious crisis</a> over the position of royal commissioner Dyson Heydon and mounting fear on the backbench came <a href="http://www.theaustralian.com.au/national-affairs/newspoll/newspoll-canning-by-election-looks-tight-as-liberals-support-sinks/story-fnc6vkbc-1227487556628">Tuesday’s Newspoll</a>, taken in the byelection seat of Canning in Western Australia. It showed a 10.8% swing against the government in an electorate it holds with an 11.8% margin. The Liberal-Labor two-party vote in the poll was 51-49%.</p>
<p>If Canning were lost on September 19, or even run very close, Abbott’s grip on the leadership would become quite tenuous, with pressure potentially coming on him to consider a walk in the snow for the good of the party.</p>
<p>But the byelection is also a test for Labor. So if the swing were modest, Abbott would get protection and attention would come back on Bill Shorten.</p>
<p>In between, say a swing of around 8%, would be open to “spin” from winner and loser.</p>
<p>At present the predictions on both sides are that the government will narrowly retain the seat.</p>
<p>The spinning is already starting in an attempt to manage expectations. The government argues that former member Don Randall, whose death precipitated the byelection, had a very strong personal following – highlighted when lower house and Senate votes in individual WA seats are compared.</p>
<p>Labor counters by noting that when an MP dies, the swing is less than in contests triggered by a resignation, which is often accompanied by anger over the circumstances.</p>
<p>Figures prepared by the Parliamentary Library of two-party swings against governments at byelections between 1949 and 2014 show an average of 4% for all seats (5% in government-held seats). At byelections following resignations the average swing against governments was 4.9%; it has been only 2.5% where the vacancy was caused by a death.</p>
<p>But averages mask some important individual cases, because byelections can be politically defining. When, after the death of the Liberal member, John Howard held Aston in 2001 with an anti-government swing of 3.7%, it was a significant step in his recovery from the dramatic low that had seen him written off by many of his own.</p>
<p>The last time a seat changed hands after a death was in 1966 – Labor seized the Queensland regional electorate of Dawson from the Country Party. This was an early demonstration of the campaigning skills of Gough Whitlam, who was deputy leader of the ALP.</p>
<p>If Shorten wants a benchmark, he might note that the swing in Dawson was 11.9%.</p>
<p>Canning, which divides into distinct geographic sections, stretches from southeast Perth to the regional centre of Mandurah, about 70 kilometres from Perth and the second-largest city in Western Australia. Its make-up is variously described by the parties as including tradies, lower middle-class voters, “aspirational Australians” and retirees.</p>
<p>The voters’ concerns will include the basics of jobs and cost of living. The Liberals will attempt to make the contest as local as possible – about who is the best candidate to follow Randall. Labor will try to exploit the unpopularity of the federal government and Abbott, and the feeling against the Barnett state government.</p>
<p>The Liberals have been quick out with a candidate – a 32-year-old SAS captain, Andrew Hastie, who has served in Afghanistan. The party will be anxious to broaden his image beyond that of the elite soldier.</p>
<p>Labor appears to have been caught rather off guard, thinking the election might be in October; its candidate will be selected at the weekend. The frontrunner is a lawyer, Matt Keogh, but there is also interest in Kelly McManus, a one-time staffer of Kim Beazley who works in Mandurah. Labor’s vote there was low last time, so she could be well placed to maximise the pick-up in that area.</p>
<p>Abbott will be in Perth on Friday and Saturday to address the Liberal state council and do some campaigning. For most of the coming weeks, however, he will be either on his annual stint in an Indigenous community or in Canberra for parliament. He’ll obviously return to Canning but the electors are unlikely to see much of him. It wouldn’t be the first occasion that a strategic absence is seen as his best approach.</p>
<p>For both the Greens and Clive Palmer, the byelection will be important. It will be Richard Di Natale’s first test as Greens leader. Palmer’s party triumphed in the WA Senate election re-run, but since then has effectively collapsed, with Dio Wang, from WA, its only senator, down from its original three. The byelection will test whether PUP has disappeared from the radar altogether.</p>
<p>The voters of Canning will feel the political love or, more likely, be driven mad by it. The focus groups and polling will be intense; the spending will be huge, especially by the Liberals, given the stakes.</p>
<p>The mood of Canning could help determine whether Abbott’s colleagues have a “come to Jesus moment” – defined by the Prime Minister’s Office in June as a moment of collective clarity – in their view about their futures and his.</p>
<p><strong><a href="https://theconversation.com/politics-podcast-clare-oneil-and-the-future-of-progressive-politics-in-australia-46208">Listen to the latest Politics with Michelle Grattan podcast with guest, Clare O'Neil, talking about her new book Two Futures.</a></strong></p>
<iframe id="audio_iframe" src="https://www.podbean.com/media/player/3gsrk-580f97?from=wp" data-link="http://www.podbean.com/media/player/3gsrk-580f97?from=wp" height="100" width="100%" frameborder="0" scrolling="no" data-name="pb-iframe-player"></iframe><img src="https://counter.theconversation.com/content/46286/count.gif" alt="The Conversation" width="1" height="1" />
So once again Tony Abbott has told the Coalition partyroom that he’s ticked off his cabinet ministers. Read them the riot act, he said. They seem to be slow learners, those ministers. Or, more to the point…Michelle Grattan, Professorial Fellow, University of CanberraLicensed as Creative Commons – attribution, no derivatives.