Potential of pomegranate peel extract as a natural additive in foods

During the last years, there has been a continuously growing demand from the food industry for additives from natural sources (e.g. plant materials) as an alternative to synthetic ones that have been associated with toxic effects. Moreover, the fact that the consumption of functional foods could boost the immune system and resistance of the human body against viruses, has been a priority for consumers through the last decades. This trend has been magnified during the coronavirus disease 2019 (COVID-19) pandemic and is expected to remain high also within the post-lockdown and post-pandemic era.Pomegranate is one of the healthiest fruits worldwide with a significant amount of various phenolic compounds. The processing of pomegranate into juice generates huge amounts of by-products, such as peels and seeds, leading to disposal issues and environmental pollution. Pomegranate peels contain higher amounts of bioactive compounds, mainly phenolic acids, flavonoids and tannins, than the edible fleshy parts. These compounds possess antioxidant and antimicrobial properties that inhibit the process of lipid peroxidation in fatty foods and scavenging free radicals and prevent the growth of microorganisms, respectively. In this perspective, the present review analyzes and critically discusses the state of the art about the current and potential uses of pomegranate peel extract (PPE) as a natural food additive. The enriched food systems (e.g. meat, poultry and fish products, dairies, edible oils and fats), the form of added extract (crude or encapsulated), the method of extraction employed, the extract concentration and the main outcomes of each study are reviewed and discussed.Crude or encapsulated pomegranate peel extracts increase food stability upon processing, storage or gastrointestinal digestion conditions by inhibiting oxidation as well as the growth of pathogenic microorganisms. In most of the studies, the addition of PPE was not found to negatively affect the sensorial properties of the final products up to a specific addition level.