Your compost bin could be a plastic factory

Here is something that has been thoroughly categorized by scientists all over the world, and has been used in a variety of applications: bacteria.

Here are two problems: food waste and plastic pollution.

Here is a solution: Bacteria that feed on food waste and have a product of usable plastic.

It may seem like a fantasy, but scientists have been developing sustainable methods of using endogenous pathways inside bacteria that produce plastics from carbon sources. With food waste being well documented as a significant portion of all landfill waste, and plastic production contributing largely to global greenhouse gas (GHG) emissions, diverting food waste to controlled microbial processing facilities will address two problems at once.

Some bacteria can produce a diverse group of plastics known as Polyhydroxyalkanoates (PHA) as a by-product of their regular metabolism (Nielson et al. 2017). This plastic is bridgeable, can be easily moulded into different products, and is a thermoplastic, which means it does not interfere with the recycling process if it is thrown into a blue bin rather than a green bin (Campbell 2019). Luna Yu is a researcher at the University of Toronto who is working to perfect this technique. She specializes in creating PHAs through her start-up Genecis that are used for high-end products such as 3D printing filament, flexible packaging, and medical equipment.

Current hindrances of this process have included the cost of viable carbon sources, which compromised 28-50% of the total production process (Nielson et al. 2017). Although food waste may intuitively be the best carbon source, its composition is often too impure to feed to the PHA-producing bacteria directly (Nielson et al. 2017). Straight food waste must first be pre-treated and processed into basic compounds like simple sugars and fatty acids, which can then be used by bacteria to produce PHAs (Nielson et al. 2017). This process, however, can also be done through genetically engineered bacteria as opposed to using laboratory chemicals (Campbell 2019).

Stressors such as nitrogen and phosphorus starvation are often needed to induce the PHA-producing mechanisms, which adds layers to the work needed for this process to work (Nielson et al. 2017). Using synthetic biology and engineering, however, this system can be hijacked so that the bacteria can constantly produce PHAs (Nielson et al. 2017). A specific strain of Escherichia Coli, the standard organism used in genetic engineering, has been modified to contain A. latus genes that create PHA (Nielson et al. 2017). This strain of E. Coli can produce a dry weight of 80.5% PHA to the weight of a single cell, which means 1kg of dry bacteria would yield 805g of plastic, for example (Nielson et al. 2017). In their paper, Nielson et al. (2017) present a table outlining various combinations of food waste categories, kinds of PHAs that are produced, and the bacterial genes responsible for them.

With future advancements, it could be possible that the technique of converting food waste into plastic could be integrated into modern households. Plastics are a commodity that has become abused and overused to the point where today people cannot envision a world without a plastic grocery bag or disposable utensils. Not only do plastics often pollute our environment and oceans, but their production also involves using oils and natural resources that pollute the earth even more. Investing in synthetic biology to produce bridgeable plastics can change resource use in more ways than one.


Campbell, D. U of T startup that turns food waste into high-quality bio-plastic eyes next phase of growth. University of Toronto News. Posted 24 September 2018. Accessed 12 June 2019. Available from:

Nielsen, C., Rahman, A., Rehman, Rehman, A. U., Walsh, M. K., Miller, C. D. Food waste conversion to microbial polyhydroxyalkanoates. Microbial Technology. 10(6), (2017).



A Chicken in Hand is Worth Ten Apples in the Bush

How many bags of compost do you generate in a week because your food went bad? One or two? But how about supermarkets? Every time you buy food, you may look for the items that look freshest. The one with the furthest expiry date. Most firm. Most ripe. Most pretty. You are not the only one that seeks these characteristics in the food products you buy, so what happens to the food that gets left behind? Once food items become spoiled to the point that supermarkets have deemed they will not be bought, they become waste.

Between six supermarkets studied in Sweden over a three-year period, 1570 tonnes of food waste (excluding bread) was generated (Scholz et al. 2015). Comparatively, the average person in Sweden generates 72kg (0.072 tonnes) of food waste each year. Scholz et al. (2015) analyzed the mass composition and ratio of annual supermarket waste and found discrepancies between the number of food items wasted per category, and their relative greenhouse gas emissions. Results showed that while fruits and vegetables comprised a whopping 85% of food waste by mass, they only contributed to 46% of the wasted carbon footprint (Scholz et al. 2015). As for meat products, they only contributed to 3.5% of the wasted mass but 29% of the total wasted carbon footprint (Scholz et al. 2015).  

In addition to the environmental impact, Brancoli et al. (2017) also state that meat waste contributes more to a supermarket’s economic loss than produce. One technique to reduce meat waste is outlined by Eriksson et al. (2016) whereby reducing storage temperature results in lower quantities of waste. Eriksson et al. (2017) described that changing the storage temperature for deli products from 8˚C to 5˚C results in 15% less food waste. They also point out that minced meats, which are often stored chilled, could be kept frozen to reduce their wastage as well. For produce, the authors categorized the main contributors to still be fresh, edible, and have a high quality (Scholz et al. 2015). This wastage is likely due to supermarkets often providing 7% more food than expected as customer demands can be difficult to project, and as newer and “better” products replace old, although still edible, ones (Brancoli et al. 2017). 

Supermarkets do have tools to reduce their food waste. Keeping foods frozen and at different temperatures, and possibly purchasing less, are small steps that could make big a difference.


Brancoli, P., Rousta, K., Bolton, K. Life Cycle Assessment of supermarket food waste. Resources, Conservation and Recycling. 188, 39-46 (2017).

Eriksson, M., Strid I., Hansson, P. Food waste reduction in supermarkets – Net costs and benefits of reduced storage. Resources, Conservation and Recycling. 107, 73-81 (2017).

Scholz, K., Eriksson, M., Strid, I. Carbon Footprint of Supermarket Food Waste. Resources Conservation & Recycling. 94, 56-65 (2015).

Alternatives to the Composter!

Food waste occurs from parts of food that we deem to be waste, but in some cases, we can do something with those off-casts. Below is a list of food items I see others commonly throwing in the composter, but that I as a home chef have found other ways to use.

Baked Broccoli and Cauliflower Stems Recipe

  1. Chop stems into disks.
  2. Mix in some olive oil, paprika, garlic powder, salt, and pepper with the disks.
  3. Bake disks in the oven at 450˚F for 30 minutes or until crispy brown (this time could change depending on how big your disks are).

Fried Potato Skin Recipes

  1. Heat canola oil in a skillet about 1cm deep.
  2. Pat dry potato skins with a towel.
  3. Fry potato skins on oil until crispy and brown.
  4. Scoop out potato skins with a draining spoon and put onto a plate lined with a paper towel.
  5. Sprinkle with salt and serve.

Avocado Appetizers In Skins

  1. Ensure you have cut the avocado into two symmetrical halves, keeping the flesh as intact as possible.
  2. Dice the flesh.
  3. In a frying pan, heat olive oil and pan-fry the diced avocado with some salt and pepper.
  4. When crispy and golden brown, put the fried avocado into the skins for a fancy presentation, and garnish with salsa to-taste. Serve with spoons.
  5. I also like to use the avocado skins for individual guacamole.

Fruit Pulp Crackers

This is a recipe I found on OneGreenPlanet, but always works!

  1. Mix all of the ingredients below in a food processor, and thinly spread the mixture on a baking sheet:
    • 2 cups juice pulp
    • 1 tablespoon chia seeds
    • 1/2 cup flaxseeds
    • 3 tablespoons tamari
    • Dash of turmeric
    • 1 teaspoon dried oregano
    • Black pepper, to taste
    • 1/4 cup water, or a bit more to allow contents to mix in the processor
  2. Bake at 320˚F for 40-50 minutes and flip halfway through.

Flavoured Banana Peels
This recipe one I found on a youtube video. When I make it, I omit the cumin seeds and coriander powder because I find them overpowering.

  1. Dice one or two banana peels on a cutting board.
  2. Heat about two tablespoons of oil in a pan.
  3. Add in some fennel seeds, cumin seeds, and mustard seeds.
  4. Mix in the banana peels and add chilli powder, salt, coriander powder, and lemon juice.
  5. Continue cooking until the peels are reasonably golden brown and serve

Can Animals be Composters?

On my volunteering trip to a rural part of Panama, the compound at which my team stayed often had stray dogs that circulated the outdoor dinner table every night. We scared 3 or 4 different dogs away every time in fear of catching diseases they might spread, but we were puzzled as to why they kept coming back. On the last day of the trip, we found that our leftover food was being left outside every night for the dogs to feast on just meters away from the dinner table. 

Image preview

A stray Panamanian dog resting as she waits for us to finish our dinner

My team and I were shocked—in Canada, some individuals buy heavy-duty lockable trash bins or even go as far as tainting their garbage with poison to deter animals from getting to it. In Panama, they treat wild animals as part of their community. I wondered if it is because humans have a stronger emotional connection to dogs as opposed to raccoons. Or, maybe in North America we are too concerned with attracting pathogenically contagious vermin (a valid argument), and not consciously allowing our street to look “dirty”. Why are Panamanians not concerned like we are? In the previous trips I’ve been on to Central America, the cultures are often described as being much more “community-oriented” compared to the North; they have tighter relationships and interact more frequently with neighbours, and I argue that this strong sense of care to each other extends to the wildlife around them. Panamanians are more concerned with the well-being of the stray dogs in their community than the detriment to their health or aesthetic brought by the animals’ presence.

The United States Environmental Protection Agency describes feeding animals as the third tier in their food recovery pyramid, preceded only by source reduction and feeding other people. Click here to go to their website. Surprisingly, composting—the holy grail of mitigating food waste—is tier five of six on their pyramid, which puts into perspective how beneficial feeding animals our food scraps could be.

Am I suggesting you start a food scrap pile in your neighbourhood? 

No. The reality is, stray animals can still carry diseases, be nuisances, and maybe even be aggressive. Given the structure of some cities and towns, feeding animals might not be easy to do, and it is not always safe. Just because Panamanians have grown accustomed to this lifestyle does not mean it can be replicated everywhere. 

That does not mean, however, that your food waste should always be destined for the composter—which brings me to my second point. For the many of you that have pets at home, there is a large variety of foods that can be safely consumed by cats and dogs including certain meats, veggies and grains. Dogs specifically evolved alongside humans eating their leftovers, and it was not until the past several decades that industries began heavily marketing synthetic dog food. If you are unsure of what you can feed to your pets, you can always reference reputable internet sources or contact your local vet—it may save resources and your money.

Some Universities and institutions are even donating food scraps to nearby farms. Everyday, 1 ton the food scraps from the kitchens at Rutgers University go directly to the hogs and cattle of a nearby farm. The university only pays half of what it would to the city’s organic collection system, and the animals get to enjoy a healthy variety of food. If you live near farm, this extra step could be an option for you too.

Although it may not be ideal to live exactly like generous Panamanians, we North Americans can still learn from their lifestyle to reduce our food waste in an alturistic manner.

Tub or Tube?

I am sure we all know the irritating feeling of having food right in front of us and not being able to eat it, and then having to throw it away. 

But, let me be more specific—you are famished and holding a nearly empty tub of Nutella. Your spoon is just enough to reach the bottom, and the container is too small for your big hands to really have any autonomy over it. The more you scrape, the harder it becomes to fill your spoon. You enjoy any little bit you can manage to get on the tip of your silverware, but you know you will soon have nothing. And then it happens. In the midst of the adrenaline and hopefulness you had of having a fulfilling snack after a long day of work, you accept that you have lost the battle to the Nutella container and can’t get any more onto your spoon. As you lick the messy fingers of one hand, the other hand throws away a jar cumulatively containing at least a whole delicious spoonful of hazelnut spread into the garbage. A tragedy to your taste buds, but there is nothing else you could have done.

If containers like those of Nutella jars had been designed differently, maybe you would not have been left in sorrow wondering if you should have tried harder. Not only can it be a tough play on our emotions, inefficient food packaging is a considerable source of food waste. Nutella is not the only brand guilty of forcing us to waste food—peanut butter, condiments like ketchup and mayonnaise bottles, salsa jars, glass bottles of thick sauces like teriyaki, and even yogurt cups all leave behind dirty containers that often end up either down the sink or in a landfill. 

If you were to add up all the ketchup you’ve thrown away during you whole like from “empty” bottles, how many new bottles could you fill? One? Five? Food waste in landfills is a significant producer of methane, a greenhouse gas 30 times more potent than the infamous carbon dioxide.

Not all packaging favours food waste like the examples above. Yogurt tubes, freezies, and bagged milk allow you to perfectly squeeze out all the contents, popsicles can be sucked until only a compostable wooden stick is left, and butter wrappers perfectly peel off the block when it is cold enough. Trying to decide between a tasty treat and being conscientious of the environment can often require making sacrifices; without our continuous awareness of climate change, however, we might not be around for too long to be able to make these decisions.

It’d just be nice if they made tubed Nutella.


100 Meter Diet

variety of vegetables

Photo by Ella Olsson on

Imagine hardly having to go to the supermarket. Imagine having a variety of healthy food available at your fingertips. Imagine having almost all the food you could ever need growing in the comfort of your own backyard.

Though this exact kind of a life might seem almost imaginary, a woman in Toronto named Julie nourishes herself with her own 4×8 meter vegetable garden for a large portion of the year, a style of living that she calls the 100 Meter Diet. Having spent a large portion of childhood on her grandparent’s farm, Julie became familiar with different kinds of edible plants, their optimal growing conditions, growing seasons, and today still learns from growing plants she is not familiar with. Julie says growing food has always come naturally to her; although it may seem as difficult labour for many, she finds picking fruits and making jam a relaxing part of her everyday life.

Julie grows a variety of foods while ensuring that at least something is always ready to harvest during the summer. For example, she says she can collect a lot of asparagus at the beginning of the summer, but must wait for squash until the end. Preparation for the garden happens year-round, however, with garlic being planted in the fall and starting pepper and tomato seeds indoors as early as mid-February. Julie clarifies, however, that she cannot always be completely independent, as she does not grow too many protein-rich plants like chickpeas, cannot grow certain herbs and spices because of Canada’s climate, and does not have access to animal-based products like eggs and milk, which does lead her to the supermarket for certain foods.

Even as an experienced gardener with an academic background in forestry, Julie subscribes to different magazines such as Small Farms Canada and experiments with different techniques of growing every year. She says to ensure not too many of one thing is planted at the same time, as she mentions a time when she accidentally planted too many radishes and they all went to seed, making it so they could no longer be eaten. If she has an excess of food, she often pickles it in jars, freezes it, makes jam, or shares it with her neighbours. Julie loathes food waste, and keeps her own composter in her backyard which she feeds right back into her crops whenever she can.

Julie’s garden is built from passion, history, and her devotion to sustainability. If you are looking for a way to eat healthier and more locally, starting you own backyard garden – or even participating in a community garden – is an amazing first step.