The pomegranate is a fruit belonging to the family Lythraceae (Punicaceae) and the genus Punica. Its Latin name Punica granatum, which translates as Phoenician apple, suggests that the Phoenicians introduced the fruit to the Mediterranean. In the UK, pomegranates are cultivated in various regions, particularly within the Aegean and Mediterranean areas.
Pomegranate peel constitutes a significant by-product in the industrial processing of the fruit, particularly the production of pomegranate juice, as the fruit contains 26-30% peel by weight. Various studies have shown that pomegranate peel contains numerous bioactive, antioxidant compounds that are significantly higher than those found in pomegranate seeds, apple peel, red wine and green tea. For example, one study reported that pomegranate peel contains antioxidants that are 114 times more concentrated than those found in pomegranate seeds, 5 times more concentrated than apple peel, 3 times more concentrated than red wine and green tea. The structure of the pomegranate contains several bioactive components, including punicalagin, ellagic acid, delphinidin, gallic acid, kaempferol, rutin and quercetin. Pomegranate arils contain polyphenols including anthocyanins, ellagitannins, galagyl esters, hydroxybenzoic acid, hydroxycinnamic acid and dihydroflavonols, which have powerful antimutagenic, antioxidant, antimicrobial and apoptotic properties. The pomegranate's antioxidant effect provides protection for liver and heart health, as well as antihyperlipidaemic, antihyperglycaemic, and anti-ageing benefits.
Furthermore, research has demonstrated the antioxidant properties of bioactives present in pomegranate peel, which in turn provides protection for gastric mucosa, prevents cancer, and offers therapeutic effects against ethanol-induced ulcers and diabetic oxidation.
The study investigated the probiotic impact of pomegranate peel extract, loaded with phenolic compounds, on the intestinal microbiota, which is particularly linked to the risk of obesity in high-fat diet-fed mice. The extract boosted the number of bifidobacteria in the ileal lumen but had no effect on weight gain, glycaemia, and glucose tolerance. Additionally, it reduced serum cholesterol levels (LDL/HDL).
Pomegranate peel and extract are useful natural additives for improving the quality and extending the shelf life of food products, acting as antioxidants, antimicrobials, colourings and sweeteners, while also possessing impressive nutraceutical properties.