I have spent my week on twitter in a series of quite interesting discussions about, of all things, bananas. This started thanks to a tweet from a local journalist showing a pile of individually wrapped bananas with the comment: “you gotta be kidding me”. On the surface it seemed like a fair concern. We all know about over-packaging and so it is a reasonable reflex to assume that this was just another case of unnecessary packaging. The problem is that in this case (like many in the environmental field) initial impressions can often end up being wrong. Sometimes when you dig deeper into an issue you discover unexpected truths. This banana case provides a useful example of how looking deeper into a story can show our initial impressions to be wrong on complex environmental topics.
So why might wrapping a banana be a good idea from an environmental perspective? As we all know, bananas can be extremely perishable. In warm weather a banana seldom lasts more than a week in my house. Refrigerating bananas doesn’t help a lot either. So why is this the case and how do they ship these perishable fruit from the orchard to market? Like many of my posts we need to start with a quick chemistry lesson.
The secret to banana ripening is a chemical called ethylene (ethene for chemists). Like many fruits, bananas emit ethylene as they ripen and the more ethylene a banana is exposed to, the faster that banana will ripen. A rotten banana emits large (relatively speaking) amounts of ethylene and can thus increase the rate of ripening of any bananas nearby. This is common in fruit and explains the old expression “one rotten apple ruins the barrel”. So to defer ripening you need to keep your bananas from being exposed to or emitting ethylene. In the shipping industry they do this by shipping bananas green, cold and in a controlled atmosphere with low oxygen levels and elevated carbon dioxide concentrations.
When the preserved bananas reach their destination they are sent to a local ripening facility At the ripening facility they are gently warmed (really they are allowed to return to ambient temperatures in a controlled manner) and they are exposed to a precise amount of ethylene (it is injected into a sealed exposure room). Once exposed to ethylene the race is on to get the bananas to the store to be sold and eaten before they go bad. Unpackaged bananas have a shelf life of about 15 days.
This brings us to why a banana company might want to package bananas. To answer this question let’s go to a useful article on the topic: Effect of packaging materials on shelf life and quality of banana cultivars which explains:
Banana remained marketable for 36 days in the high density polyethylene and low density polyethylene bags, and for 18 days in banana leaf and teff straw packaging treatments. Unpackaged fruits remained marketable for 15 days only…. It can, thus, be concluded that packaging of banana fruits in high density and low density polyethylene bags resulted in longer shelf life and improved quality of the produce followed by packaging in dried banana leaf and teff straw.
So by packaging bananas (and protecting them from additional ethylene exposure) a distributor can more than double a banana’s shelf life from 15 days to 36 days. This is a very significant improvement. As Nick Eagland pointed out to me, outside of the distribution channels there is an entire literature on life-hacks which describes how individual consumers use cling wrap to get the same effect.
I am not the first person to address this issue and a previous writer, interested in the topic, went to Del Monte (the distributors of the bananas in question) to ask them why they do it. In an interview on the topic Del Monte explained that beyond extending lifespans the packaging had another use:
the product serves another important role, namely the ability to now offer healthy alternative snacks to consumers in locations when they were previously not available due to the highly perishable nature of bananas.
Everyone knows that there is an obesity epidemic and healthy eating could be an important step forward to address the health and economic consequences on society. A great example of the positive contribution that the Del Monte CRT [“Controlled Ripening Technology”] single finger bananas is the fact that now school children, when they go to their school vending machine, can choose a banana instead of, let’s say, a chocolate bar or potato chips (which coincidentally also use plastic wrappers).
So here we have an example of a business decision, that both extends the shelf life of a banana and contributes to improving nutritional opportunities for kids…seems like a no-brainer right? But we are not finished because besides being good for kids this may also be good for the global environment? How you ask? Well for that we have to remember that each banana is the result of a long production chain and each step in that chain has a large fossil fuel (carbon) footprint. Thus every banana that goes into the trash is wasted fossil fuels and thus wasted carbon emissions.
Here is a link to a discussion of the carbon footprint of your average banana. The most recent research indicates that the carbon footprint for bananas are in the 1.27 kilogram to 1.37 kilogram CO2 per kilogram of bananas. You read that right, each banana results in the generation of more than a banana’s weight in CO2 emissions. Pretty terrifying right? Actually this isn’t bad by food standards. Consider that grass-fed beef can have a carbon footprint of over 25 kilograms of CO2 per kilogram of beef. That doesn’t mean we aren’t getting better according to Agriculture and Agri-Foods Canada:
in Canada the mean carbon footprint of beef cattle at the exit gate of the farm decreased from 18.2 kg CO2 per kg LW [live weight] in 1981 to 9.5 kg CO2 per kg LW in 2006 mainly because of improved genetics, better diets, and more sustainable land management practices.
As for the other fruits? The lowest CO2 fruit are likely apples. Local apples can have a carbon footprint as low as 0.108 kilograms of CO2 per kilogram of apples. Want organic apples? That will increase it to 0.176 kilograms of CO2 per kilogram of apples.
What is even worse is food waste. In retail stores wastage of fruits and vegetables represents a huge environmental cost. One study identified that the fruit & vegetable department of a grocery store contributed 85% of the wasted mass and 46% of the total carbon footprint of wastage from the store. So if the use of a few milligrams of plastic wrap can save kilograms of wasted CO2 emissions, that seems like a pretty good deal for the environment.
Now it is clear that packaging is not the ideal solution for most retail outlets. Most consumers are going to want to (and should) buy unwrapped bananas and avoid throwing out old bananas by making banana bread. But for convenience stores and locations where people will buy and consume individual bananas, the individual wrapping of bananas seems to be an environmentally sound practice. It reduces wastage, extends shelf-life and can have a net effect of reducing overall carbon emissions. So an example of a counter-intuitive result that is ultimately true. So the next time someone gives you a quick and easy answer to a complex question consider that the real answer might be a lot more complicated and your knee-jerk response may be the wrong one.