Food wastage has become a hot topic with everyone from the United Nations to numerous NGOs decrying the size of the loss and promoting opportunities to do better. Though I have been critical of some of these reports which usually don’t include any analysis of what a major reduction in food wastage would mean for the entire food system (smaller processing and retail industry sales and employment, as examples), I agree that less wastage would be beneficial in many ways.

There have been some excellent studies. To cite one, Dr. Mike von Massow and colleagues at U Guelph measured the quantity and composition of weekly food wastage for 94 Guelph households that had at least one child. An average of about 3 kg of food per week was found in their household garbage or 230 kg worth an estimated $936 per year. About two-thirds was fruit and vegetables. If an average household had three people, that’s about 80 kg and $312 per person/year. If multiplied by 38 million Canadians, that’s about 3 million tonnes and $12 billion – with almost all of that going to landfills or composting.

The United Nations estimates than 17% of global food is lost or wasted, 14% of that post harvest, and about 11% of the 17% in households. Reference here. If Canadians consume about 26 million tonnes of food per year (reference here), the measurements of wastage by von Massow et al equate (albeit calculated crudely) to about 12% of that – essentially the same percentage as the UN figure.

Though I’ve not provided more references, my impression is that other studies also show food wastage percentages to be in the range of 10-20% with the majority of this being perishable fruits and vegetables.

So it was a real surprise to me when I saw a couple of high-profile reports from University of Guelph researchers in past months stating that Canadians lose or waste about 58% of all food and food ingredients. That includes this recent publication from researchers whom I hold in highest regard.

The 58% figure seemed away too high for me, and inconsistent with the other reports. I decided to dig deeper.

It turns out that it comes from a study done by the consulting company, Value Change Management Inc (VCMI), for Second Harvest, a food bank in Toronto. There are two publications – a shorter summary written by Second Harvest staff – and a 118-page full technical report written by VCMI. Both are accessible here. The following comments pertain mostly to the latter.

Two key tables in the technical report are these (FLW means food loss and wastage, HH means household and HRI means hotels, restaurants and institutions):

From Table 3.2 we see that, unlike in the other studies, most of the loss (21.89 million tonnes, or nearly two-thirds of the calculated total 34.89 million tonnes of annual food loss and wastage) involves field crops – mainly grains and oilseeds. It’s not fruits and vegetables as in other studies. And only about 5 million tonnes (2.76 + 2.38), or 15%, is at the consumer level.

Table G enlarges on this, showing that a total of 65% (5% + 8% + 30% + 6% + 5% + 10% +1%) of field crops are loss or wasted in the food chain process.

The technical report is rather vague as to where all these numbers come from. But, it appears that in the case of grain corn that I am most familiar with – they have first taken a crude estimate of the percent of total Canadian grain supply used directly for feed – 60% for corn (also 30% of wheat and 80% of barley) using base figures rounded to the closest 10% provided by this feed industry source. Then they have assumed that all the rest of the corn is used to manufacture food. Hence, they assumed that the difference in weight between the 40% of non-feed corn (adjusted for imports and exports) minus food products produced from corn is all loss or wastage. It’s true as they’ve noted that Statistics Canada does not segregate annual data on corn usage for food and industrial processing, but it seems very incorrect to assume that it’s all (or even mostly) food. And if the same was assumed for usage/processing of all other grains and oilseeds, the error could be huge.

To check further, I had a telephone conversation with two principal researchers at VCMI and it appears that this is only partly right. In the case of soybeans, for example, where about 80% of processed weight ends up as livestock protein feed, they did not assume the 80% is loss or wastage. But in the case of corn, it looks like they did. Other grains are partly in between.

For corn, the 40% for processing produces non-food products like fuel and industrial-grade ethanol, carbon dioxide (which has a surprisingly strong market demand despite greenhouse gas concerns), paper coatings, protein byproduct feeds and more. This is not food loss or wastage.

The authors take some pains to differentiate between planned (or unavoidable) losses and unplanned (or avoidable) losses. See the red columns in Table 3.2. However, this does not really correct for the original flaw. And in the higher-profile material released from this study (see the adjectives like “staggering,” “depressing” and “enormous” used by Second Harvest), it’s the 58% total figure that gets most play.

In summary, I believe that 58% wastage or loss is grossly misleading.

There are three other questionable assumptions in the report that I’ll mention briefly.

1. In the production of processing crops (good examples being tomatoes and fresh peas in Ontario), it is standard practice to plant more crop than is needed for processing in an average year. This is to ensure that there is still enough crop for processing in years with poor growing conditions – or years when high temperatures mean crops in the field reach and pass the harvestable stage (eg., peas, sweet corn) too quickly for the processing plants to accommodate. Without this allowance for excess in average or better years, there would not be enough crop to meet processor needs in unfavourable years. There are processes in place – for example, crop insurance – to ensure that farmers are compensated financially in years when their crop is ‘bypassed.’

There is, at best, a vague reference to this practice in the technical report. In the summary written by Second Harvest, it states ‘thousands of acres of produce are plowed under due to cancelled orders’ which likely includes this practice. Labelling this as wastage or loss seems misleading as it implies that a societal goal should be its reduction. One could obviously eliminate it if farmers were only to plant enough crop to meet processor needs in better-than-average years. But that would mean plant shut-downs and insufficient food supply in all other years – hardly an appropriate or responsible solution.

2. The technical report makes an estimate of the value of the food loss or wastage by dividing total value of food produced/marketed in Canada by total tonnes of food. Hence, all wastage and loss is assumed to be worth $4,351 per tonne (the figure is about 10% higher for losses in the HRI sector). That includes agricultural product losses at an early stage of processing and lower-value byproducts like ethanol, paper starch and livestock feed protein. That does not seem realistic.

 Also, the report implies that if this calculated wastage and loss did not occur – meaning that total food supply were    100%/(100% – 58%) or 2.4 times (240%) as large as at present – the value of Canadian food would be 240% higher too. This ignores obvious questions like “Who would eat the additional supply?” It also ignores the basic economics of supply/demand balance.

To the suggestion that it could be mostly sold for export, my response is “At $4351/tonne, I don’t think so.”

3. My third point seems trivial by comparison, but in the technical report it refers to a 10% loss in onion production attributable to moisture loss during conditioning for storage. However, the same process occurs with several grains including grain corn. Corn dried from about 24% moisture at harvest to 15.5% or lower for storage also endures a weight loss of at least 10%. If the onion calculation was applied to field crops, the calculated Canadian loss and wastage percent would be even higher than 58%.

In summary, I’d recommend that reviewers and others not use 58% as a meaningful estimate of loss and wastage in the Canadian food system. The United Nations figure of 17% seems more appropriate. The 17% loss is still in serious need of reduction, for a world faced with feeding 10 billion by about 2050, but it’s not nearly the 58% calculated in the Second Harvest reports.