Food Waste: Slimmer Waste-line

Why does so much good food end up in the bin?
21 January 2020
Presented by Katie Haylor, Chris Smith
Production by Katie Haylor.




This week: food waste. Worldwide, a third of the food we buy ends up in the bin. Why? And what can science do to help? Plus - will 2020 be another climate record-breaker, and what are the climate-change consequences for future food production here? A new way to treat type 1 diabetes. And why, nutritionally-speaking, packed lunches for many children leave a lot to be desired...

In this episode


01:02 - Climate change and UK farming

What will climate change mean for growing crops in the UK?

Climate change and UK farming
Professor Ian Bateman, University of Exeter

This week scientists confirmed that 2019 was the second hottest on record, worldwide, and that the last decade was the hottest for 150 years. It’s a trend likely to continue: researchers are already predicting that 2020 will be another record-breaker. But what’s happening in the UK, and what are the consequences for one thing our green and pleasant land is famous for: farming? According to a new report, for a while, climate change could be good for Britain’s agriculture, bringing warmer weather and the right amount of rain to grow high-value crops. But there’s a sting in the tail: if global temperatures rise by more than 3 degrees - which is entirely feasible - this could be enough to halt the Gulf Stream and make the weather take an abrupt turn for the worst. Chris Smith spoke to Ian Bateman, who authored the new study…

Ian - What we're showing is the effect of expected climate change and extreme climate change upon agriculture in Britain over about the next 60 years. As the climate warms, Britain will respond to that by being able to grow more than it did in the past. However, we show that if it warms too much, then actually there will be effects on what is commonly called the Gulf stream that keeps Britain warm, which actually will be quite negative for this country.

Chris - Let's look at the good news side of it first, the fact that you thought there might be an increased productivity. How did you make those assessments and appraisals?

Ian - First of all, we looked at farmers' behaviour over the whole area of the UK for about the last 60 years, and some years are really warm, and some years are pretty cold and you can see farmers responding to that. And because you now understand that relationship, you can then say, well, what will happen if the weather changes in a certain direction into the future?

Chris- And under those scenarios it shows that will at least stay the same or we could even see a slight increase in productivity?

Ian - Staying the same, I'm afraid, that's not an option anymore. Climate change is already proceeding so rapidly and you've seen that in the results announced just today actually, this is the warmest decade ever. The 19 years of this century to date are 19 of the 20 hottest years ever recorded. So what we're looking at is what will happen if climate change proceeds as expected and in a country like Britain, that means we will get warmer and in the growing season, drier conditions and that'll allow us to grow a lot of high value crops.

Chris - What about water though Ian, because this is very important for crop production and it's not that the whole country gets the same amount of water everywhere. How do we take that into account?

Ian - So even under what we might call standard climate change, you are going to get areas, particularly in the East of the country, which are going too get to dry for agriculture. Now we have sufficient water falling on the country as a whole to irrigate, so if we are prepared to invest in piping water across from the North and the West, which will still remain fairly wet, there will be enough water to irrigate. But what we show in the paper is that the costs of doing that will exceed the value of the extra crops. But one of the big things that we looked at in our paper is what if it's not standard climate change? What if instead it's more extreme? And that's where things get really bad, I'm afraid.

Chris- What do you call really extreme though?

Ian - Standard climate change, we're looking at anything up to, sort of, two degrees, hopefully not much more than that over say that the average person's lifetime here. In the extreme scenario, there is an effect on Britain, which is almost different to every other country in the world, and that's for a very specific reason. Britain is warmer than you would expect for a country that is so Northern in the world. So, you've got to realise Edinburgh is north of Moscow. This country should be really, really cold, but we're not because we benefit from what people call the Gulf Stream, that huge warm current awards that comes across the Atlantic from the Caribbean and keeps us relatively insulated from the cold North. Unfortunately, if climate change proceeds fast, what you're going to find is that the melting of the Arctic glaciers on Greenland is going to disturb that Gulf stream and push it south so that unfortunately all that hot water instead of coming up to us, it'll push straight across the Atlantic. The results for Britain then is that we go from getting warmer and warmer and warmer to suddenly by the time you get to three degrees getting colder. Scientists call it a tipping point. It'll be cold and dry.

Chris - Have you put any financial numbers on these numbers as in have you said, and if we then compute what the cost of this is, in terms of the return for the beneficial scenarios versus the really extreme scenarios, what's the economic cost of this?

Ian - Yeah, we have done that. When you're looking at the more extreme case, you're looking at values that aren't that far off about a third of the value of farm production. These are substantial figures. You've got to add on to that, which we haven't done, the fact that it's not just us that's going to be affected. We import a very large proportion of our food from abroad, but if the rest of the world is suffering actually worse consequences from climate change than us, in the extreme case, the world will be very challenged to feed itself. Adding that onto these consequences makes it a much more worrying situation.

PTSD, trauma, mental health

07:25 - Potential treatment for PTSD

What could a newly-identified protein complex mean for PTSD?

Potential treatment for PTSD
Dr Camilla Nord, Cambridge University

Post-traumatic stress disorder (PTSD) is a common anxiety state triggered by frightening or distressing events. Sufferers speak of becoming hypervigilant for danger, and often develop disabling flashbacks to the events that precipitated their problem. But now scientists in Canada have found a chemical marker that’s present at higher levels in the brain when a person develops PTSD, which might reveal new ways to tackle the condition. Camilla Nord is from Cambridge University’s MRC Cognition and Brain Sciences Unit and has been looking at the new work for us, and she spoke to Katie Haylor...

Camilla - So at the moment there are two main routes to treatment with PTSD. Perhaps the most common is a type of cognitive behavioural therapy, a psychological therapy that really focuses on the trauma, and tries to recontextualize it and reduce those kinds of fear related responses or traumatic flashbacks. And the second is different types of antidepressant drugs, which seem to show some efficacy in treating PTSD.

Katie - And how well do these two approaches work broadly speaking?

Camilla - Neither are perfect. I think the evidence suggests that psychological treatments are a little bit better than antidepressant drugs. But, of course, one of the main symptoms of PTSD is a sort of depression-like state and antidepressant drugs can be quite effective at remedying that, whilst the PTSD-specific psychological therapies can be a little bit better at remedying the flashbacks and the more memory dependent effects.

Katie - So tell us about this study then, what did they seek to achieve?

Camilla - So this study was quite unusual because it proposes a new molecular treatment for post-traumatic stress disorder and it does that by combining mouse research, in which we can look at levels of this new protein complex in mice, with some human results giving it a kind of translational "maybe we could use it in the clinic" type result.

Katie - Okay. Can you just break down what they actually found out?

Camilla - The first was that they found this receptor protein complex. It's got this really wordy name called the glucocorticoid receptor FK binding protein five one complex. So I'll just call it the receptor protein complex. And what they found was that this complex, the levels of it are raised in patients with PTSD but also in a mouse model of PTSD. And then they created their own little protein called a peptide that competes with the FK protein to bind with the glucocorticoid receptors and that essentially makes levels of this whole complex reduce. So maybe a potential treatment for this raised level of the protein complex.

Katie - Do we know practically what it's doing to, say someone's symptoms of PTSD, what's going on in the memory recall or things like that?

Camilla - I think that's totally unclear in human patients because that level of mechanism was only explored in animals. But what did seem to happen in the animal model, which is a kind of conditioning model, so you've got to imagine these mice are essentially exposed to, I think it was a light and a sound, and then they get a foot shock. And once you do that for not very many times, the mice developed this freezing response to the light and the sound. And that freezing response continues even when they don't get the cue. And that's what they call their PTSD symptoms and you could reduce that with this drug. And that gives you a little idea of the sort of avoidance symptoms that could be targeted in humans with this drug.

Chris - That sort of addresses the question I was going to ask you, Camilla, which is how do we know that this complex is bound up with getting the symptoms and it's not just a marker that's nothing to do with causing the symptoms it's just produced as a spinoff of them being there?

Camilla - I still think that both are entirely possible. What you have to remember is that the clinical symptoms of PTSD, as you've already mentioned actually, are things like flashbacks as well as avoidance responses and things like mood. And those more complex areas of symptoms are not modeled at all in a rodent model. So all they have is this kind of freezing avoidance response, so all we know about is the mechanism of that particular avoidance response and how that could maybe be reduced with this new peptide.

Katie - So is this a therapy or is it a diagnostic marker or both?

Camilla - The authors suggest that it's both. What their one human result shows is that in 22 patients with PTSD, levels of this protein complex are different in the same direction as the animals, and they think maybe this could be a diagnostic marker. But what you have to remember is that first of all, it's 22 people and it's not necessarily everyone, at least in their data, that shows that difference. So it's a strong suggestion that it could be a diagnostic marker, but not proof.

Katie - How significant do you think this is?

Camilla - I think it's quite significant for future scientific research. I think I would be a little more tentative about the clinical significance, but certainly what excites me a lot about the results is that I think it opens up a whole new range of studies that we need to do about this protein complex.


New cell transplant for diabetes
Professor Shareen Forbes, Edinburgh University

Diabetes - and a better way to manage the condition in some people. Diabetes comes in two forms; type 2 diabetes is usually associated with being overweight and it’s more common in older people. Type 1 diabetes, on the other hand, often begins in childhood and is caused by the immune system attacking the islet cells in the pancreas, meaning that patients can’t make any of the insulin they need to control blood glucose; instead they have to inject it. But despite this, for some people the condition can become extremely difficult to control. When this happens, doctors sometimes resort to a procedure called an “islet cell transplant” to replace the lost insulin-producing cells with donor cells. While this can control blood sugar, the downside is that patients need to take immune-suppressing drugs, and the benefits may only be short lived. Now, researchers in Edinburgh have discovered a way to boost the effectiveness of the transplanted cells: by adding alongside them stem cells collected from the umbilical cords of newborn babies. Chris Smith spoke to Shareen Forbes…

Shareen - So in an islet transplant, a pancreas is donated, the insulin producing cells are isolated, they're purified, and the vein to the liver is actually identified and the islets are actually infused. Just fire a needle into this vein!

Chris- And those cells presumably drift along and then lodge in the liver where they do the job they would do in the pancreas but they're doing it from within the liver?

Shareen - That's right. But there are major issues in that the islets go in without a blood vessel supply. Then blood vessels form within the first 48 hours to seven days. So they're very vulnerable to dying off in that period.

Chris- And when you do one of these transplants, how long does the effect or the benefit last for?

Shareen - That can be very variable. In many patients the graft function can deteriorate and it may last maybe 10 years.

Chris- And you have got a way of improving the prognosis, have you?

Shareen - We're hopeful that our experiments might lead to further experiments, in man, where we're hopeful that this might actually have improved effects. My colleagues at the Scottish National Blood Transfusion Service characterised and made something called stromal cells from umbilical cord. So this is umbilical cord that would normally be thrown away and these cells they found produced growth factors and also affect the immune system. And what we found when we co-transplanted these cells with the islets, blood glucose levels were improved for a longer period of time and the rejection of the insulin secreting cells was less, as compared to our parallel experiments where just islets alone were transfused into the mouse models.

Chris - So you did this in mice. Where did you put the insulin secreting cells, the islet cells, with these new umbilical cord derived cells? Where did you put them?

Shareen - So we put them both under the kidney capsule, which is an experimental route, which allows us to assess the vascularisation well, so the amount of blood vessel formation well. And with that route we showed that the amount of blood vessel formed was much greater in the mixture of the cells with the islets as compared to the islets alone. And we also transplanted them into the liver, so we emulated the clinical scenario in man and showed again that the effects on blood glucose control was much improved.

Chris - Do you think this is just attributable to the blood vessels behaving better when you've got these umbilical cord cells there or do you think that the umbilical cord cells are manipulating the immune response as well?

Shareen - I think that it's both factors which are important. The cells have a lot of anti-inflammatory properties and they also can modulate the immune response. So I think there's a protective effect there, as well as what you've mentioned, enabling the formation of blood vessels to form much more quickly and therefore protect the insulin producing cells.

Chris - And if you do a comparison of a mouse that doesn't get these new cells but does get the islet transplant and a mouse that gets the same islet transplant, but with some of these new cells, how much better off is the second situation?

Shareen - We show in our study that actually blood glucose levels are mainly cured. Mice that received the islets alone, their blood glucose levels would double versus, those that received the same number of islets plus these cells.

Chris - So do you think this is a realistic clinical prospect now, to take what we know works in these mice and translate that to people? Because we are using umbilical cord blood STEM cells in the clinic at the moment for other things, aren't we? So presumably there's already a tried and tested route for using these sorts of cells so it's not such a leap to now translate this?

Shareen - We need to go into larger animal models and then do safety studies before we go into man. But certainly it's a realistic step change in the field.


What causes solar flares?
Gregory Fleishman, New Jersey Institute of Technology

Solar flares are areas of unusual brightness in the Sun. Now we have a better idea what causes them. Adam Murphy reports…

Adam - At the heart of our solar system, the Sun pumps out incomprehensible amounts of energy, that allow life on this planet to exist. But sometimes that energy gets a little more concentrated into what's called a solar flare.

Gregory - What happens fundamentally, some energy is very quickly being released and converted to various forms of energy; energy of motion, energy of heating and energy of energetic charged particles. And this manifests a phenomena which we call a solar flame.

Adam - That's Gregory Fleishman from the New Jersey Institute of Technology explaining a solar flare. But the scale of these things is spectacular as well. A single flare can release more than a billion, billion joules of energy, and is capable of sending particles streaming all the way here to Earth. But what is actually going on in the Sun? How do solar flares get going?

It wasn't something we had a very strong idea about, what the catalyst was, but using an array of telescopes in California looking at the microwave radiation the Sun is giving off, just like the energy in a microwave oven, Gregory's work may shine a light on it.

Gregory - What we found, we found that the magnetic field at the flare location decays very quickly and very strongly. For example, in the beginning of a flare in a given location, you may have magnetic field. We quantify magnetic fields in units called Gauss. So for example, initially you observed 1000 Gauss and after this release, the magnetic field dropped by a factor of five. It's only 200 Gauss and all this 800 Gauss of magnetic field, like 80% of magnetic field strengths disappeared, and transferred to other forms of energy. And these other forms of energy is energy of accelerated charged particles. It's energy of heated plasma and also energy of microscopic motions, also observed from the same location.

Adam - The Sun's magnetic field is very strange. Unlike Earth's magnetic field, which is roughly the same shape as a bar magnet, the Sun's magnetic field twists and turns and changes, and it looks like these play a key role in the generation of solar flares. And as these fields twist and scrunch and collide and combine, they give off huge amounts of energy. And these telescopes in California give us a new level of detail with which to measure solar flares.

Because the thing about flares is that we can't predict them. And if particles from a particularly strong one hit the Earth at the wrong time, they could damage the communication systems the planet relies on. And this work could be the first step towards predicting them.

Gregory - We are quantifying now what we could call "nowcasting", so we can analyse it in almost real time, and we can predict severe space weather effects. We can predict what will happen in the space plasma close to the Earth produced by such flares.


21:58 - What's in your lunchbox?

Are kids eating enough vegetables in their packed lunches?

What's in your lunchbox?
Dr Charlotte Evans, University of Leeds

Fifteen years ago the chef Jamie Oliver made a stand to get schools to dish up healthier lunches for their children. His message did get through, and now school lunches do have to follow stringent nutritional guidelines. But the same obviously isn’t true for kids’ packed lunches, and a new study suggests that because they often don’t have enough vegetables, many children aren’t getting the nutrients they need as they grow. Phil Sansom spoke to researcher Charlotte Evans from the University of Leeds - and adults’ packed lunches are often as bad as kids’ ones...

Charlotte - We have surveyed children's packed lunches twice, once in 2006 and again in 2016, and what we found was that sugars had really come down quite a lot, and this was due to fewer children taking a chocolate bar or a sugary drink to school. And also the portion size of some sweet foods like yogurts and cakes had reduced. But one of the downsides is that there are still children, many children, who are not having any salad or vegetables in their packed lunch. So only one in five children had some vegetables.

Phil - How old were these children?

Charlotte - These children were aged eight to nine years old. So children who are younger have a free school meal under the universal free school meals scheme.

Phil - And how many kids do take a packed lunch versus a school meal?

Charlotte - About half of the children in this age group take a packed lunch and about half have a school meal.

Phil - Well, they're eight to nine years old. I'm 25 and I also bring in a packed lunch. Can you rate how mine compares? I've got here, this toasted sandwich in clingfilm and I've also brought in this Apple and a couple of chocolate biscuits.

Charlotte - Well that's not sounding too bad. Have you got any vegetables?

Phil - No, salami and cheese.

Charlotte - Well that's one improvement that you could make, but it's great that you've got fruit and you've got dairy and plenty of protein. You know it would be good to have some vegetables in there as well.

Phil - Is that the key message for the children's packed lunches then, that there needs to be more vegetables.

Charlotte - I think a lot of adults and parents think that children don't like vegetables, and vegetables aren't a children's food, but vegetables are so nutrient dense that it is really important that children eat vegetables every day.

Phil - There's been lots of campaigns for school lunches. Jamie Oliver comes to mind as the most famous campaigner. Why are you focusing on packed lunches instead? ‘Cause that seems like something that you can't really control.

Charlotte - Since the food standards came in for school meals in 2006, they have continued to improve whereas packed lunches haven't changed as much. So there's this gap in the quality between packed lunches and school meals. So we do encourage children to have a school meal. But of course there are lots of different reasons why children might choose not to. I don't want it to be all about parents and making parents feel guilty, because it is very difficult to pack foods like vegetables in a child's lunch when they don't want them or they don't want something different from what that friend eats.

So you know, having a universal packed lunch policy could be helpful, although it's still telling parents what to do. Another option would be to subsidise school meals, and we know that the cost is an issue for parents. So if school meals were cheaper than it is very likely that a higher proportion of children would have a school meal rather than a packed lunch.

Phil - Would you like to see something like free school lunches like you have for the younger ages? Up to age nine or ten?

Charlotte - I'd like to see subsidised school meals. To actually have free school meals for the whole of primary school would be quite expensive. And I'm not sure that the government would want to spend that much, but there are certainly some countries like Sweden and Finland, that have decided that it is worthwhile, so it is definitely something to consider, but if free school meals aren't possible, I would still say it's worth subsidising them to any extent just to reduce the price.

Phil - And what are the consequences for kids if they continue to not get enough vegetables, for example?

Charlotte - Well, children do need to have a nutritious diet, and we found that there were some nutrients such as vitamin A, zinc, and iron, that are found in fresh foods like vegetables and fruits, that were very low in packed lunches, and although we don't see out-and-out deficiency in children, if they do have a sub-optimal diet during childhood when they're growing and developing, then it could be possible that the risk of noncommunicable diseases like cardiovascular disease are increased later in life.


28:52 - Indoor farming - the future?

Adam Murphy hears about a less traditional approach to farming...

Indoor farming - the future?
James Lloyd-Jones, Jones Food Company

According to the sustainability charity WRAP, almost 1 in 5 lettuces grown in the UK go to waste. In general, fruits and vegetables have the highest wastage rates. But in a warehouse in Scunthorpe, Jones Food Company director James Lloyd-Jones is taking a less traditional approach to growing his produce. For one thing, the whole operation is inside, and you’d be hard pushed to find some soil. James took Adam Murphy on a virtual tour...

James - It looks exactly like Willy Wonka's TV room. It's large, white rooms with white apparatus, with white light that comes through over the crops. So it's very spaceship-esque. So the crops... our largest facility is over 12 metres high, and they are on carrier trays that get moved around the facility as a crop grows, and it allows for the crops then to go from seeding, to germination, to growing period, back to being harvested, and recleaned, and seeded again. So it's a big moving machine that you would be immersed in.

Adam - Immersed in farming that looks like a spaceship? That sounds fun to me. The Jones food company is a hydroponics lab that's currently growing things like herbs and dill. And since hydroponics is a word I first heard on Star Trek, the future feeling is fitting. But what is hydroponics?

James - Hydroponics in its simplicity is growing without soil, using nutrient-rich water. Hydroponics isn't new, it's been around since the Aztecs. The Hanging Gardens of Babylon were hydroponic. And the 1965 Pan-Am used to have a hydroponics facility where they would land to refuel on their longer journeys.

Adam - So if there's no soil, and you're inside, which means there's no sunlight, how do you grow things in that?

James - I'm not going to say it's a simple way of growing indoors. There's lots of nuances, but it does take away elements that you would find in greenhouses or field-grown, but that does still provide us with other challenges. Which would effectively be: controller lighting; nutrient patterns to optimise the plant's growth throughout its life; temperature; wind; and humidity. Effectively we go from a seeding onto a substrate, into a germination room for a couple of days, and then that goes onto the racks, which then move from one end to another ready for harvesting as the plant grows throughout its life; and then it runs through automated harvesters, and then the crop goes in one direction and the operators that were used to transport the crop go the other, ready for cleaning and reseeding. To replicate lights indoors we've effectively got 2.8 metre long LED lights which cover the trays in a very uniform manner, so the lighting is similar across all the crops.

Adam - Well then, you can grow crops, and you can control the conditions. You can even do things like grow strawberries all year round. But how does that help with problem of wasting food?

James - The way this combats food waste is you can plan how you crop, effectively. If your customer is going to make 11 million sandwiches a week and they need X amount of produce in tonnage, you can seed and grow and produce in a very controlled manner all the way through the year, to reflect the, say, 11 million sandwiches a week. So we're not having to then oversow or undersow; everything is very predictable. So the wastage is vastly reduced. And also, because you're not refrigerating and flying it in, or putting it on a ship to bring produce in, you're cutting all that waste away as well that you would have to overgrow, oversow, overharvest, so that when you're importing it, you've still got a buffer. Our buffer is vastly reduced because it's so close to source.

Adam - Beyond food waste though, what advantages can vertical farming give us? Beyond sounding sci-fi?

James - Oh, it's a huge amount of advantages. There's three things you've got to think about hydroponics: it's people, produce, and power. If you can remove people out of the growing systems you're not introducing dirt, so that's why we automate a lot. Power: one of the largest contributors to carbon emissions is modern agriculture. We're aiming to be completely carbon neutral by the end of 2020. We are adopting some very exciting technology which can produce electricity, heat, and CO2, and the CO2 goes into the growth chambers. The heat will be used to work with the water patterns that we've already got to help sterilisation. And the power of course will be used for the environment and light power needs. That takes away the power elements, or the power problem. And then the produce is the third P, and effectively, if you can have year round specification-grown crop which goes into the food supply chain, pretty much at source, that's much better than growing and importing from all over the world because you can maintain a nutritional quality and it can be delivered and eaten within hours.


34:41 - Extending food shelf life

How can plasma help to keep fruit and veg good for longer?

Extending food shelf life
James Walsh, University of Liverpool

Once food has been grown or raised, it needs to be distributed to customers. And food is routinely shipped or flown all around the world, so storing food in a way to minimise spoilage during the trip is a key area ripe for research. One idea being developed involves bathing food items with chemicals that can boost the defences of fruits and vegetables, and kill the microbes that make things go bad so they last longer. Chris Smith spoke to James Walsh from the University of Liverpool...

James - Well, there's several non-thermal processing technologies currently in use and currently being investigated as well. An example would be ultraviolet light, so we expose products to ultraviolet light and that can kill microbes on the surface. And another quite topical area is chemical methods, so chlorine washing or applying ozone to decontaminate those products.

Chris - And are there no negative effects on the products by doing that? I would imagine that bathing something in ultraviolet light, which is quite high energy, quite ionizing, might be bad. Does it not affect the flavour?

James - Well, there's actually very strict guidelines on that so if there's any change to the products, so nutritional changes or changes to coluor or flavour or anything like that. Then that novel processing technology is subjected to some extremely sort of strict guidelines and there has to be several years of very expensive testing to prove it's actually safe to use before any consumer would ever eat a product treated by that method.

Chris - And with these sorts of methods, how much shelf life can you add?

James - Well, it depends a lot on the method and it depends a lot on the product as well. The particular method I am interested in, which is using plasma to treat products, that can, from the literature, it appears to give between one and four days additional shelf life depending on the type of product you're actually treating.

Chris - Now when you say plasma James, most people when you say plasma, we'll think of the stuff that washes around in your bloodstream and carries blood cells along. This is a totally different type of plasma, isn't it?

James - Absolutely. So this is a plasma, as in the fourth state of matter. So if you imagine you took an ice cube and you warmed it up, you'd get a liquid, you warm that liquid, you get steam. If you warm that steam, what comes next? Well that's actually a plasma. And in that plasma you've actually got a soup of ions, which have got a positive charge, electrons which you've got a negative charge and lots of reactive chemical species. And that's what really does the business in plasma technology.

Chris - How would it be used then? Would you generate the plasma and then spray it on to the food stuff as it sort of goes along on a conveyor belt?

James - That's essentially the idea. Although the plasma is only there whilst you use electricity to generate the plasma. The plasma is only there while you're applying the electricity. So it's really generated when and where you like it. So as you can imagine, you create a plasma or over a conveyor belt, the products pass underneath and they get exposed to all these chemical species and some UV light as well, and that's what actually damages the spoilage organisms on the surface.

Chris - So it zaps the bugs, things like fungi and moulds that would want to degrade the food, but it doesn't degrade the food item itself?

James - Well it's a very fine line where we're sort of treading there. So it's, there's a vast amount of research on finding the correct dose of plasma species to be able to get rid of those organisms that we don't want on the surface, but not have any sort of underpinning impact on the food matrix, that's really the key to this technology.

Chris - I spoke to Kirsty Bayliss who's a researcher at Murdoch University in Western Australia and she's doing something similar. I spoke to her about a year ago and she said that the effect it has on the foods that they've tested, she said to me quite literally, she can take an avocado and have it last in her fridge for three weeks, not three days. And she wasn't exaggerating. She was saying though that the extension in shelf life she's getting is way beyond what can be accounted for just on the basis of suppressing or removing the microbes, because after all they will just come back again later from the environment. So she was thinking there must be something else going on and perhaps that the exposure to these plasmas changes almost like the immune system of the fruits and vegetables. It makes them more resilient and resistant so they can fend off assault from the microbial flora and fauna better.

James - It's definitely a possibility, although I'm not so familiar with that area of research. An alternative sort of theory for that could be that if there's water on the product, you actually activate that water, you give it some chemical reactivity and that lasts much longer than natural gas plasma you're applying. So it has a longterm effect for sure that can give shelf life extensions for longer than a few days.

Chris - When you do the numbers, do the maths, as they like to say, on this, does it translate into a viable prospect? As in there's gotta be infrastructure put in place to do this. You've got to have the machinery, you've got to have plant that's capable of actually processing things in this way. When you add up the cost of all of that, does it translate into a benefit?

James - The figures are still being run, I'd say. But actually plasma technology is a very low cost because it doesn't use any consumables. You don't have to make anything in a factory and transport it to where you are processing your products. You actually create it in situ using only air and electricity. And also the amounts of electricity, the power is, is very low. It's sort of hundreds of watts per square metre of plasma generation. So that's, that's really low. It's less than boiling a kettle for example.

Chris - So when you make your cost benefit analyses for this sort of work, what's your bottom line? How much do you think that the industry could save if you were to implement this technology?

James - Well the types of products we're interested in, commodity products, say tomatoes and salad leaves and things like that. There's a tiny margin of profit made by those food producers on those. So we really, we have to get those costs down for the plasma treatment to be sub pennies per product as it were, to make it viable.

Chris - But the return for them? How much are they actually going to potentially save and make if they can extend the shelf life?

James - There's an enormous amount for both producers and consumers to save. If you can extend shelf life just by a single day. So producers, obviously they can employ people to not work weekends for example, so they can have that extra day storage. Or it was passed onto the supermarkets, they can last longer on the shelves. And of course the biggest loss of food in the UK is in households, 70% of it. So that extra one day shelf life may translate into maybe an £800 a year saving for an average family. So it's quite enormous.


40:27 - Food waste in your fridge

Why do we buy food, that we end up throwing away?

Food waste in your fridge
Cathrine Jansson-Boyd, Anglia Ruskin University

So far we’ve discussed limiting food waste in production and distribution, but a major contributor to food waste is what we throw away at home. So why do we buy stuff that we end up throwing away? Katie Haylor and Chris Smith spoke to consumer psychologist Cathrine Jansson-Boyd from Anglia Ruskin University. First up, Katie asked, what can studying the way we think of food tell us about why so much of it ends up in the bin?

Cathrine - To start off with, we can get a good understanding of perhaps why are we buying it in the first place. So if we think we get a good bargain, buy one get one free, then if we think that's important, then we're more likely to buy two. But however at home we may not use it and it might end up in the bin because we bought something just because we thought it was a bargain to start off with.

Katie - So are we talking about shops' behaviour, or are we talking about consumer behaviour, or both?

Cathrine - We're talking about both. So consumers of course in theory should be in charge of why they're purchasing something in the first place. But it's never as simple as that, as marketing, shops and so forth know all the tricks of the trades to try to entice you to buy more because it's more profitable if you do, of course.

Katie - What could, or can, or are, retailers doing to help minimize food that they are wasting potentially, and then food that we might be wasting at home?

Cathrine - Well if they wanted to help us to change our behaviours - because that's really what we're looking at, we need to rethink why we're buying things - a good start would be stop using packaging for fruits and vegetables, which has expiration dates on. Because that tells consumers you shouldn't use something after a certain date, when actually often in fact it's still perfectly useable. Um, but we don't look at them, instead we look at the date. So if we could change that, that would be a good starting point as one example.

Chris - Can we get rid of best before dates or is there a legal reason why they have to be there, Catherine? Cause I must admit I've met people, even members of my own family, a yogurt will go one day over this magic best before date and then magically they've decided that's now inedible and it goes in the bin. You say look, come on 12 hours. Do you think it's really made a difference? And they chuck it. If we could chuck away best before dates. I think the psychology wouldn't be there to chunk the food away would it? But are they there for a reason? Are they there for legal reasons?

Cathrine - They're not actually there for legal reasons. They are there because they're meant to act as a guideline. Now, I think a better system would be to say perhaps display by dates in the shops so the shop knows "now we've got three or four days" or whatever, but then consumers should use a bit of common sense. Of course, if you're buying fish and it smells really badly, then no one's going to want to eat it and I understand that. But often again, you can actually taste test things even in your own home, to see whether or not it's still edible. It's a bit of a risky game perhaps at times, but you can use common sense and if you use common sense, hopefully you won't put it in the bin, you'll still use it. If you get consumers to use common sense, feel empowered, that they're taking charge of things they can save money and money is something that consumers quite often like to save all fairness.

Katie - Is part of the problem our expectation when it comes to food? Perhaps we expect certain, especially fruit and veg to look a certain way. I know I'm awful, I'm really picky with apples. I do judge some apples before I pick it up as to whether it looks like an apple I would expect. Is it the right colour, is it the right shape? That kind of thing. Are any shops getting this right, do you think?

Cathrine - I am not so sure that they are getting it right because we are trained as consumers to like the aesthetics of anything we purchase, whether this be food or anything else. And the reality is it's not about taste, but we are now so conditioned into actually believing it has to look a certain way, that we won't, like you said, we'll look at an apple and judge is this really an apple? And that's where food waste often starts, because they actually throw away tons of fruit and vegetables because they don't look the part. So if we could change and go back to "it's fine to have something that perhaps looks a little wonky. It doesn't taste any different", then that would be a very good start in terms of reducing food waste.

Katie - So once you've got your food, you've made your decision, you've got at home, asking for a friend, do you have any tips on organization? Because there's a load of stuff in the fridge. Sometimes things go to the back that should be at the front. I think I could do a bit better when it comes to organizing stuff in priority order of eating it.

Chris - You should come and look at my fridge at home!

Katie - Cathrine, can you give us both some tips?

Cathrine - Well again, this is often to do with time. You don't want to rush. So people often, again, they're rushed in the supermarket, they come home and they just kind of jam everything in wherever it fits. And that's where people go wrong because you can't then see what's what, and you need to kind of stack them a bit like the supermarkets do. The ones that you think is going to expire first needs to go at the front. And again, if you want to be very well organized when you're actually purchasing things in the supermarket, you write them down on your shopping list that you presumably have with you, that tells you exactly what you're going to buy and say this will expire on such and such date. So if you then had decided to have your mac and cheese on the Monday and the cheese is going to expire on the Tuesday, maybe move that and move something else up to the Monday that is actually expiring before so that you have the list in parallel with what you're purchasing.


46:08 - Fish food from abattoir waste

Can the waste water from abattoirs be put to better use than going in the bin?

Fish food from abattoir waste
Navid Moheimani, Murdoch University

However much progress is made towards reducing food waste, arguably some waste is inevitable. But what if it could be re-purposed? Scientists in Western Australia have found a way to make better use of the waste water from abattoirs. And, if you’re eating right now, you might want to put down your knife and fork for a few minutes! The group have developed a process to use the nutrient-rich blood and other waste material left over after animal slaughter and turn it into a food for other valuable foodstuffs like prawns and shellfish. They first pass the waste water through an anaerobic digester to convert the organic molecules to methane (which can be used as an electricity source), leaving a liquid rich in ammonia and phosphate. These compounds are fed large pools containing algae, which are aquatic plants. The algae use them, together with light, to grow. Chris spoke to Murdoch University’s Navid Moheimani. First up, he asked, quite how much waste water are we talking about that abattoirs need to get rid of?

Navid - I've done just a little calculation this morning and from a single abattoir in WA, we can generate something around 400 tons of algae per year.

Chris - So it's literally, Olympic swimming pools' worth of water regularly coming out of these industries?

Navid - Yeah, something in that line.

Chris - How do you use it then? Have you've got a swimming pool that you actively fill and turn into an algal bath?

Navid - So the algae grows in there, they take up all of these in-organics, which are nitrogen and phosphorous, and they convert it to the goodies - protein, lipids, and carbohydrates. Those are now very valuable for the aquaculture, for instance, and we can use them as a prawn feed.

Chris - Algae need a lot of light. Are these pools that you put the water in outside? They're just effectively a pond? Or have you got some other clever setup for growing the algae?

Navid - So we try to keep everything as cheap as possible. So these ponds - we're not introducing any other systems - we use a technology called raceway ponds. The shallow Raceway with a paddle wheel on it, which would cause the mixing. So mixing is very important because that mixing would allow the algae to receive the light.

Chris - Is this a continuous process or is it a batch process? Do you fill a pond up, stir it up, let the algae grow, get the algae, chunk the water away? Or do you feed a bit of water in steadily and let the algae continue to grow?

Navid - We call it semi continuous because algae would only receive the light 12 hours a day. We cannot continuously harvest it, but we can semi-continuously harvest it during the day and add the new effluent to it.

Chris - And how do you get the algae out then?

Navid - That's potentially the hardest part of the whole process. The algae, even in the most concentrated, algal pond is still something around one to two grams of algae per litre. So concentrating that is one of the challenges that we face. However, we've been looking at very novel technologies for taking the algae out of the water.

Chris - Cause people sometimes use things like ultraviolet light, which makes the algae die and get charged, so they all clump up and then you can filter out the clumps.

Navid - That can be done. We don't necessarily like to kill them in the water because if we kill the algae in the water, that means that they would release some of the stuff that inside of the cell out of which we don't want to do that. We want to collect them as healthy as possible because then that we can feed it back to the aquaculture organisms.

Chris - And once you've got the algae, what do you do with it then?

Navid - If you are using it as a fertilizer in agriculture for instance, we can use it wet. If we are using it as an aquaculture feed, we need to dry it, we need to palletize it, and then we can directly use it as a feed for aquaculture organisms such as prawn, marin, crayfish, etc. It depends where you are.

Chris - And is this environmentally sound? We're very worried about feeding animals to animals because of the risk of cycling various toxins, other possible infections and so on. Is there anything that might be in there that could be picked up by the algae, concentrated by the algae and then introduced back into the food chain? Because at the end of the day, these things are going to be fed to things that could be eaten by humans, or even eaten directly by humans, so it's got to be safe.

Navid - That's a very good question. So far in none of the animal waste that we are dealing with, we picked up any heavy metals. We also didn't pick up anything toxic. However, if you are dealing with the waste, which can potentially contain a huge amount of heavy metals, you're right, algae may be able to accumulate those. So far we dealt with the piggeries waste and also abattoir waste. We could not detect any heavy metals or any toxic in the process.

Chris - Antibiotics that are given to farm animals? There's also questions about some drugs, some hormone treatments. Could these things be concentrated? And also some algae make toxins in their own right, don't they? Blue green algae. Not that you're going to grow any of those, but they exist. And things like ciguatera toxin, which you get from the ocean.

Navid - Normally the cyanobacteria or dino-flagellates are the one which cause toxic algal bloom or they are producing toxins. The species that we're using, the green algae. These guys don't generate any toxins. Now, antibiotics, and you're right, somebody may actually feed antibiotics to their animals. However, the process we're going through is not directly using the effluent. The effluent goes primarily to anaerobic digestion. It's already treated. So if there is any antibiotics at that point, it's already been gone. If not, the process of anaerobic digestion wouldn't work, so I'm fairly confident that there would be no hormones and no antibiotics by the time that we get the effluent to grow the algae.

Chris - Say I'm an abattoir owner. How much revenue could I see coming back from this? What would previously have been a complete waste stream that I have to pay money to get rid of?

Navid - I don't have all of the numbers, but I can just summarize it this way. That right now, as you rightly said, this effluent is not being used anywhere in the world. So now we can potentially produce 20 grams per square metre per day of algae generated from this. We think that the cost of producing of the algae is around $1 to $1 50 cents a kilogram. Even if you're not putting any value on the water which has been cleaned, if we can sell the algae anything higher than $1 50 cents a kilogram, we generating revenue for the abattoirs.

Chris - You're very lucky here in WA that the sun shines a lot more than it does, say, in Britain. To what extent is that going to determine the viability of doing this? Because abattoirs are everywhere, but the sun doesn't shine everywhere.

Navid - This process would work in every place that you've got light. Now, if you don't have access to the light in some places such as a Scandinavia, they've got access to a huge amount of geothermal that would generate very cheap, at some points, even free electricity. You can use those electricity to generate the light, to grow the algae in more contained conditions. In some places, some other places, I have to admit, this may not work, so it's not a unique process that can work everywhere in the world. You must give them light. Light is a must for the algae.


52:28 - Take home tips to tackle kitchen food waste

How can you minimise the amount of food that gets thrown out from your fridge?

Take home tips to tackle kitchen food waste
Cathrine Jansson-Boyd, Anglia Ruskin University

We’ve only just scratched the surface of the conversation around food waste! Katie Haylor asked consumer psychologist Cathrine Jansson-Boyd from Anglia Ruskin University for a few take home tips...

Cathrine - It's all about being practical and trying to take an organised approach to shopping. Try to decide on a weekly basis what you're going to eat for every day of the week. Are you going to eat out? Then you know you don't need to buy something for that particular day. Make a very structured shopping list. Go to the supermarket, or online shopping, wherever you do shopping, buy only exactly what you think you're going to need. And don't fall for any extra sort of bargains, or resist those, make sure you have plenty of time when you're in the supermarket because when you're rushed, you tend to make decisions that aren't based on the practicality of what you're actually needing.

Chris - Do you think the answer might be to encourage people to grow more of their own? If you look at the times when food was more precious to us because we had to go to a lot more effort, and we had to spend more money to get it, we were much more careful with it. And it's now we've got this embarrassment of riches and we don't actually care for it.

Cathrine - The more ownership you take over anything in life, including food, the more likely you are to make sure that you're actually using it. So that could be one way forward, absolutely. But of course, not everybody has a garden to grow their own food, in which case we need to be more practical. And equally they should consider going with a set budget, only buy exactly the items that you need for a certain kind of amount. And hopefully people also will reduce their spend on things like sweets.

Chris - Do you think that the loss of home economics classes in schools for a whole generation, people my sort of age; it had been dropped from the curriculum, regarded as a bit boring and not very sexy - it's back now, a bit, but not perhaps as much as you could do - but people don't really understand the value of food, so they don't necessarily repurpose things. "Ooh, I'll turn those vegetables, they're looking a bit iffy, I'll turn them into a stew now." People don't think like that.

Cathrine - Of course that would be helpful. Maybe we need to start teaching children at a young age what it actually means to reuse food, so we all have a better understanding of it. Part of what's actually gone missing in the process is people are scared to be creative with food, but if you have some not so nice looking vegetables, you can actually still reuse them, you can do something. But you might not know what to do with them unless you're happy to be creative and experiment a bit with food, come up with a different type of recipe. What could you do with your leftovers if you're stuck with loads of vegetables? Well, that's up to you to come up with. Maybe make a nice vegetable stew or a curry or something, where it doesn't matter about their appearance. But people do need to be more experimentally enticed when it comes to different types of dishes and food use.

A sperm and egg meeting

55:41 - QotW: Why don't women's bodies reject sperm?

Take a listen to this rather fertile question of the week...

QotW: Why don't women's bodies reject sperm?
Graham McKinnon, iCASH Peterborough

Sexual health doctor Graham McKinnon helped us out with this question from listener Jure...

Jure - Why doesn’t a woman’s body reject sperm as a foreign object?

Phil - It really would be the ultimate form of birth control, wouldn’t it? I went to Graham McKinnon, who’s a doctor and a consultant in sexual health. He explained how the sperm stays safe as it goes through the cervix, across the uterus, into the fallopian tubes, and eventually gets to the egg.

Graham - The female reproductive tract, like any other part of the body, needs to protect against infection via the immune system. A healthy immune system is one which recognises and eliminates anything that is foreign to it. But there have to be exceptions to that. We call those exceptions ‘immune tolerance’.

Phil - The key exception in this case being sperm. If the immune system treated sperm the same way it did a virus, then nobody would ever get pregnant, and oops, there goes the human race. And in fact, some people’s immune systems do react like this.

Graham - The 2% of women who produce antibodies to sperm are often infertile. So it is a delicate balancing act, and the consequences of it going wrong can be significant.

Phil - So what’s doing the balancing in this balancing act? What’s happening in the other 98% of women to create this immune tolerance?

Graham - Well the answer lies not just with the sperm, but with the seminal fluid that surrounds the sperm. A male ejaculate does not just consist of sperm! It consists of seminal fluid, which contains various other cells and bioactive substances, including a cocktail of components which alter and modulate the immune response within the female reproductive tract. In particular these prevent the development of anti-sperm antibodies.

Phil - So molecules in the semen basically act like bodyguards for the sperm. And these bodyguards come in a few different types.

Graham - Seminal fluid has one of the highest concentrations of prostaglandins of any bodily secretion.  Prostaglandins are hormone-like substances that can have immunosuppressive effects by activating immune suppressor cells and inhibiting cellular destruction. Seminal fluid also contains specialised cell signalling molecules known as cytokines which modulate the immune response.  Furthermore, specialised glycoproteins found on sperm and in the seminal fluid interact with the female immune response to suppress it. All these factors and more modulate the female immune response and that is why sperm aren’t rejected as a foreign object and are able to fertilise an egg!



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