Processing Factors Affecting the Phytochemical and Nutritional Properties of Pomegranate (Punica granatum L.) Peel Waste: A Review

Abstract

Pomegranate peel has substantial amounts of phenolic compounds, such as hydrolysable tannins (punicalin, punicalagin, ellagic acid, and gallic acid), flavonoids (anthocyanins and catechins), and nutrients, which are responsible for its biological activity. However, during processing, the level of peel compounds can be significantly altered depending on the peel processing technique used, for example, ranging from 38.6 to 50.3 mg/g for punicalagins. This review focuses on the influence of postharvest processing factors on the pharmacological, phytochemical, and nutritional properties of pomegranate (Punica granatum L.) peel. Various peel drying strategies (sun drying, microwave drying, vacuum drying, and oven drying) and different extraction protocols (solvent, super-critical fluid, ultrasound-assisted, microwave-assisted, and pressurized liquid extractions) that are used to recover phytochemical compounds of the pomegranate peel are described. A total phenolic content of 40.8 mg gallic acid equivalent (GAE)/g DM was recorded when sun drying was used, but the recovery of the total phenolic content was higher at 264.3 mg TAE/g when pressurised liquid extraction was performed. However, pressurised liquid extraction is costly due to the high initial investment costs and the limited possibility of carrying out selective extractions of organic compounds from complex peel samples. The effects of these methods on the phytochemical profiles of pomegranate peel extracts are also influenced by the cultivar and conditions used, making it difficult to determine best practice. For example, oven drying at 60 °C resulted in higher levels of punicalin of 888.04 mg CE/kg DM compared to those obtained 40 °C of 768.11 mg CE/kg DM for the Wonderful cultivar. Processes that are easy to set up, cost-effective, and do not compromise the quality and safety aspects of the peel are, thus, more desirable. From the literature survey, we identified a lack of studies testing pretreatment protocols that may result in a lower loss of the valuable biological compounds of pomegranate peels to allow for full exploitation of their health-promoting properties in potentially new value-added products.

Nutritional and Bioactive Components of Pomegranate Waste Used in Food and Cosmetic Applications: A Review

“…To produce 5.6 tons of pomegranates per acre in San Joaquin Valley, 41 gallons of fuel and over 1.2 million gallons of water are consumed [ 7 ]. On a global scale, there are three-million tons of total pomegranate production, resulting in approximately 1.62 million tons of waste [ 8 ]. For comparison measures, 68 million tons of oranges are produced globally each year, which is 8.5% of total fruit production, and it results in 15 to 25 million tons of orange biowaste [ 9 ].…”

Characterization of Alternaria Species Associated with Heart Rot of Pomegranate Fruit

“…The most successful cultivar is Wonderful, originating from California and then introduced by Israeli in Italy, which is suitable for consumption as fresh fruit and fresh-cut products as well as for processing to produce juice. Moreover, several industrial and medical applications of pomegranate peel extracts, e.g., as food preservatives, are being envisaged, as pomegranate peel is rich in phenolic compounds, which are responsible for strong antioxidant and antimicrobial activity [3][4][5][6][7][8][9][10].…”

Effects of Methanolic Extract Based-Gel From Saudi Pomegranate Peels With Enhanced Healing Potential on Excision Wounds in Diabetic Rats

“…Pomegranate consists of various phytoconstituents having wide therapeutic potential (Reddy et al, 2007;Yuan et al, 2015). Most importantly its ability to treat inflammatory conditions, cancers, cardiovascular diseases, diabetes and dental problems (Lansky and Newman, 2007;Ismail et al, 2012;Darakhshan et al, 2019;Magangana et al, 2020). Almost all sections of a pomegranate have biological activities and are used in therapy.…”