3.4.1 Fresh vs. frozen.
Fresh vs. frozen food
Ligthart, Ansems and Jetten (2005)
This study finds that frozen carrots have higher impacts than fresh, due to energy use for freezing and cold storage. Similar results are found for broccoli.
But there are questions to consider:
- To what extent does fresh produce generate greater waste than frozen?
- If year-round fresh broccoli or carrots is obtained through imports that have energy costs, might frozen produce be better outside of the growing season?
Freezing food requires energy and packaging. This research showed higher GHGs for frozen, canned and packaged (laminate carton) carrots than fresh.
Frozen broccoli has been shown to have higher GHGs than fresh broccoli, but the difference in GHGs depends on other factors such as food waste and transport.
If less food is wasted from frozen produce, then the difference between fresh and frozen in GHGs per consumed food may be less significant.
With regard to seasonality, eating frozen produce “out of season” that has been produced locally could offset the transport GHGs of eating fresh produce that has been transported long distances.
As always, the full life cycle of the product needs to be considered.
3.4.2 Packaged and canned food.
Canning and packaging increase GHGs due to material extraction, production and energy use. Here, all forms of packaging increased the GHG emissions associated with tuna.
Poovarodom, Ponnak and Manatphrom (2012)
However, these additional emissions also need to be compared to emissions from cold storage (freezing or refrigeration) of tuna meat, and potential product wastage of fresh tuna.