Thursday, August 15, 2013

The nutritional value of canned food

A few days ago I caught up with a couple of friends, and the topic turned to the value of preserving food. One of my friends was wondering whether canning and preserving was actually worth it. She questioned whether too many vitamins might get destroyed in the canning process.


I am an avid fan of canning and preserving as part of our push to greater food security, lower food costs and better nutrition for our household. 

There is no doubt in my mind, that fresh produce straight from the garden and eaten within a few hours of being picked is better than any other alternative. 

Second best is food canned from home grown organic produce which has been picked and processed as soon as possible after harvesting. 

Farmers' markets and direct farm outlets also provide another good source of fresh produce, but those are still quite rare in Australia. 

So-called "fresh" food from the supermarket, on the other hand, may not be so fresh at all. 

Let's have a look what nutritional science tells us.

The moment fruit and vegetables get harvested vitamins start breaking down. Vegetables kept in storage will have lost a significant proportion of their vitamin content by the time they get eaten:
"Nearly half the vitamins may be lost within a few days unless the fresh produce is cooled or preserved. Within one to two weeks, even refrigerated produce may lose half of its vitamins." (William Schafer, University of Minnesota Extension)
Similarly, cooking vegetables or canning fruits destroys a substantial proportion (between 30 and 50 per cent) of some vitamins, particularly vitamins A, C, B1 (thiamin) and B2 (riboflavin). In other words, after just one week in the fridge, "fresh" produce has a similar vitamin content as canned food. 

Given that most supermarket produce in Australia takes at least several days from harvest to the farm gate, the comparative nutritional superiority of fresh produce is already lost by the time consumers put their fruit and vegetables into their shopping trolley.


Is canning and preserving worthwhile from a nutritional standpoint?

Let's look at the example of tomatoes. I preserve many bottles of tomatoes every year, usually enough to last us until the next harvest. In summer, when the tomatoes are ripe and can be freshly picked and eaten straight away, there is no need for canned tomatoes in cooking. However, in winter - at least in the cold climate zones of Australia, such as Canberra region and Tasmania - the amount of food available in the garden can be very limited, and canned food is a great addition to a varied winter diet.

Australian supermarkets stock "fresh" tomatoes all year round. Sometimes they are even on special in the middle of winter. It is quite reasonable to ask whether "fresh tomatoes" from the supermarket could be nutritionally superior to my home canned produce. To my mind, there is little doubt that my sun-ripened canned tomatoes taste far better than the cardboard varieties on offer in the shops, but lets focus on nutrition alone for a moment.


Almost all of the food sold as "fresh" in our big supermarkets is at least a few days old even if it has been transported as quickly as possible from the farm to the produce market in Sydney and from there to the supermarket shelves. However, fruit and vegetables on supermarket shelves can easily be more than a week old, as reported by Choice Magazine:

Australian grown fresh tomatoes straight from the farm may be already 10 days old by the time they hit the supermarket shelves:

"About 75% of Australian tomatoes are produced in Queensland, where they grow year round. In the Bowen region they’re harvested from May to early November while in Bundaberg they can be harvested for most of the year. In summer they’re also produced in NSW and Victoria. Western Australia is self-sufficient, relying on winter tomatoes from Geraldton and Carnarvon and summer ones from the Perth area. 
So, depending on where you live, tomatoes can be well-travelled by the time you eat them. Not surprisingly, it can take 10 days or longer from when tomatoes are picked to when they arrive at your supermarket — and they can be there a few days more before you actually buy and eat them. All this time they’re losing flavour." (Choice Magazine October 2009)

In the case of tomatoes, canning could even improve the quality of the fruit. Researchers from Ohio State University found that the amount of phytochemicals such as lycopene in tomatoes can be enhanced through the process of cooking. Research into the significance of lycopene in the prevention of cancers is ongoing, but initial findings of a number of studies found that 
"dietary intakes of tomatoes and tomato products containing lycopene have been shown to be associated with decreased risk of chronic diseases such as cancer and cardiovascular diseases."

What about other fresh produce?

Other "fresh foods" are often a lot older than 10 days. The Sydney Morning Herald reported in January 2008 that
"APPLES on sale in supermarkets are up to 10 months old".
The Sydney Morning Herald asked food researcher Dr. Stephen Morris from the independent Sydney Postharvest Laboratory about the quality of apples that old. In the same article, Morries is quoted as saying that 
"Apples can be kept for six months and they will still be of very good quality. After nine months the quality is going to start to be affected and at 10 and 11 months you are not going to get such a good apple."
Fresh food storage technologies are now so sophisticated that it is increasingly difficulty for consumers to work out how fresh the produce is that we take home from the shop.

To last the distance, food is also treated with a range of chemicals, fungicides and in the case of imported fruit and vegetables, fumigated with methyl bromide to comply with quarantine rules. It may still look fresh, but it is definitely past its best:

    "English spinach, for example, retains only 53% of its folate and 54% of its carotene after just eight days stored at fridge temperatures. Apples held in cold storage for three months contain lower levels of antioxidants. With extended storage, they also lose flavour and aroma; they can go floury quickly unless kept in the fridge." (Choice Magazine, November 2010)
And of course, taste and texture suffer as well. Unfortunately for the consumer, it is often only at home when cooking or eating the produce that the inferior quality becomes obvious. Buying organic at the supermarket does not necessarily mean we get fresher produce, either.

It therefore comes as no surprise that research conducted at the University of Minnesota found that
"Vegetables handled properly and canned promptly after harvest may be more nutritious than fresh produce held many days after harvest under abusive conditions."
Happy canning!

Monday, June 17, 2013

We need to take climate change seriously NOW

Last month we passed an unthinkable benchmark - 400ppm of CO2 in the atmosphere. Yet, this terrifying piece of news made hardly any waves among the mainstream news media. Why not??? We should all be completely horrified. We should be out there working hard to change things before it is too late.

We can certainly do things on an individual level - and I firmly believe that there is a lot more individuals could do that would require a minimal investment and which would result in massive energy savings and better lifestyle outcomes. For example, our quarterly electricity bill shows how much electricity we use compared to other households in the area. Based on this chart, my family of six (parents and four boys aged between 6 and 18) uses less electricity than the average 2-person household in our area

The vast majority of households in our area are double income households, so most people are not even at home during the day. As I homeschool my three younger boys, we are at home a lot and use electricity during the day. I also cook every day on an electric hot plate and bake bread in an electric oven, and we have a range of electronic devices, so we certainly do not live a pre-modern lifestyle. It is clear to me that there is a lot of "low hanging fruit" - that is easy things individuals and families could do to improve the energy balance of their lives and thus reduce their carbon footprint. 

But that is not enough.

The latest Australian Climate Commission's Report "The Critical Decade: Extreme Weather" released yesterday said it very clearly: "Most of the available fossil fuels cannot be burnt if we are to stabilise the climate this century."

This is unpalatable news for almost everybody, especially for politicians in resources-rich Australia. It requires us to completely revamp our economy away from digging up fossil fuels towards a new society that we still have to imagine and create. 

The current Australian Labor Party minority government under Prime Minister Julia Gillard managed to put a price on carbon, but they did so without being able to communicate to the wider community how the carbon price works and what they are trying to achieve.

The carbon price has had a positive effect in reducing emissions without too much pain on consumers (who were handsomely compensated anyway), and all the doomsday scenarios conjured up by Liberal-National Party opposition leader Tony Abbott have proven to be complete nonsense. However, only cutting emissions in Australia while continuing to contribute and benefit from emissions abroad will not help fix the climate crisis. 

Unfortunately, Tony Abbott continues with his silly "Axe the Tax" slogan in the lead-up to the 2013 elections and seems committed to abandoning all sensible climate change policies if and, as currently looks likely, when he becomes Australia's next Prime Minister. 

It is easy to just throw our hands in the air and find it all too hard. It is also hard to image what our world will look like if we do not act urgently, but unfortunately, all indicators are that it will be far, far worse than the effects of acting now to prevent run-away climate change.

We already see the early effects of climate change in Australia and around the world, and it is not pretty. And we have not even reached the global 2 degree temperature increase that politicians and scientists believe will still be manageable! 

In December 2012, the Australian public broadcaster ABC's science program "Catalyst" put together a program that showed what effect global warming is already having in Australia: "Climate Change. Taking Australia's Temperature" outlines some of the visible impacts around the country. The show was produced before the "Angry Summer" heat waves of early 2013 which broke temperature records across Australia.










The full Climate Commission Report can be found here: http://climatecommission.gov.au/report/the-critical-decade-2013/. Below are the key facts from the report:

The Critical Decade: Extreme weather - key facts
1. Climate change is already increasing the intensity and frequency of many extreme weather events, adversely affecting Australians. Extreme events occur naturally and weather records are broken from time to time. However, climate change is influencing these events and record-breaking weather is becoming more common around the world. 
Some Australian examples include: 
• Heat: Extreme heat is increasing across Australia. There will still be record cold events, but hot records are now happening three times more often than cold records. 
• Bushfire weather: Extreme fire weather has increased in many parts of Australia, including southern NSW, Victoria, Tasmania and parts of South Australia, over the last 30 years. 
• Rainfall: Heavy rainfall has increased globally. Over the last three years Australia’s east coast has experienced several very heavy rainfall events, fuelled by record-high surface water temperatures in the adjacent seas. 
• Drought: A long-term drying trend is affecting the southwest corner of Western Australia, which has experienced a 15% drop in rainfall since the mid-1970s. 
• Sea-level rise: Sea level has already risen 20 cm. This means that storm surges ride on sea levels that are higher than they were a century ago, increasing the risk of flooding along Australia’s socially, economically and environmentally important coastlines. 
2. Climate change is making many extreme events worse in terms of their impacts on people, property, communities and the environment. This highlights the need to take rapid, effective action on climate change. 
• It is crucial that communities, emergency services, health and medical services and other authorities prepare for the increases that are already occurring in the severity and frequency of many types of extreme weather. 
• The southeast of Australia, including many of our largest population centres, stands out as being at increased risk from many extreme weather events - heatwaves, bushfires, heavy rainfall and sea-level rise. 
• Key food-growing regions across the southeast and the southwest are likely to experience more drought in the future. 
• Some of Australia’s iconic ecosystems are threatened by climate change. Over the past three decades the Great Barrier Reef has suffered repeated bleaching events from underwater heatwaves. The freshwater wetlands of Kakadu National Park are at risk from saltwater intrusion due to rising sea level. 
3. The climate system has shifted, and is continuing to shift, changing the conditions for all weather, including extreme weather events. 
• Levels of greenhouse gases from the combustion of fossil fuels have increased by around 40% since the beginning of the Industrial Revolution, causing the Earth’s surface to warm significantly. 
• All weather events are now occurring in global climate system that is warmer and moister than it was 50 years ago. This has loaded the dice towards more frequent and more severe extreme weather events. 
4. There is a high risk that extreme weather events like heatwaves, heavy rainfall, bushfires and cyclones will become even more intense in Australia over the coming decades. 
• There is little doubt that over the next few decades changes in these extreme events will increase the risks of adverse consequences to human health, agriculture, infrastructure and the environment. 
• Stabilising the climate is like turning around a battleship – it cannot be done immediately given its momentum. When danger is ahead you must start turning the wheel now. Any delay means that it is more and more difficult to avert the future danger. 
• The climate system has strong momentum for further warming over the next few decades because of the greenhouse gases that have already been emitted, and those that will be emitted in future. This means that it is highly likely that extreme weather events will become even more severe in Australia over that period. 
5. Only strong preventive action now and in the coming years can stabilise the climate and halt the trend of increasing extreme weather for our children and grandchildren. 
• Averting danger requires strong preventative action. How quickly and deeply we reduce greenhouse gas emissions will greatly influence the severity of extreme events in the future. 
• The world is already moving to tackle climate change. Ninety countries, representing 90% of global emissions, are committed to reducing their emissions and have programs in place to achieve this. As the 15th largest emitter in the world, Australia has an important role to play. 
• Much more substantial action will be required if we are to stabilise the climate by the second half of the century. Globally emissions must be cut rapidly and deeply to nearly zero by 2050, with Australia playing its part. 
• The decisions we make this decade will largely determine the severity of climate change and its influence on extreme events that our grandchildren will experience. This is the critical decade to get on with the job. 




Wednesday, June 12, 2013

A new beginning

It has been a while since I last wrote on this blog. Indeed, it has been close to four years. I stopped writing when I realised that between having a toddler and homeschooling two young boys, as well as growing a lot of our own food, baking all our bread, cooking from scratch every day and writing a blog, something had to give, at least for a while. In other words - I could either live the sustainable lifestyle or write about it, but not both!

So what has changed? To start with, my youngest has outgrown his toddler years and is now in his second year of homeschooling. The boys are becoming more independent and are able to help around the house. I feel that I have finally emerged from the phase of intensive early parenting and can now again focus on something beyond the immediate needs of our family.

I also felt increasingly frustrated by the noise generated by climate change deniers and anti-environmental campaigners. As many others at the time, I realised that this was an orchestrated campaign, and that there is not much point in trying to argue with people who are either ideologically opposed to science or the environmental movement or who simply have a vested interest in preserving their status quo.

Of course, given the scientific consensus that climate change is real, it doesn't actually matter what some people believe or say and how loud they are, in the end the effects will start to bite for all of us, and we better do something about it while we still have a chance.