I would expect the wasteage to outstrip the packaging and shipping contributions. Increased waste also calls for increased production and conversion from wild habitats.
I am not saying don't preserve food though, rather cut out the activities that make us need to preserve it so long. For example, shipping food internationally in cooled shipping containers. It seems pretty excessive, in some cases frivolous. Like shipping out of season fruits to Australia so we don't miss out year round.
I think I wouldn't have this opinion if shipping were carbon nuetral mind you.