Alternative feed ingredients in farm animal diets are a sustainable option from several
perspectives. Former food products (FFPs) provide an interesting case study, as they represent a
way of converting food industry losses into ingredients for the feed industry. A key concern
regarding FFPs is the possible packaging residues that can become part of the product, leading to
potential contamination of the feed. Although the level of contamination has been reported as
negligible, to ensure a good risk evaluation and assessment of the presence of packaging remnants
in FFPs, several techniques have been proposed or are currently being studied, of which the main
ones are summarized in this review. Accordingly visual inspections, computer vision (CV),
multivariate image analysis (MIA), and electric nose (e-nose) are discussed. All the proposed
methods work mainly by providing qualitative results, while further research is needed to quantify
FFP-derived packaging remnants in feed and to evaluate feed safety as required by the food
industries.