Pomegranate pomace from juice processing possesses a great potential to be used as functional food ingredients. We investigated the efficient and environmentally friendly methods to extract valuable oil, protein, and antioxidant compounds from pomegranate peel and seed separated from the by-products and determine their functional profiles. The research also determined the yields and properties of antioxidants and oil extracted from various dry and wet constituents of pomegranate, including peel, seeds, and mixture. As an integrated utilization approach, we evaluated the anaerobic digestibility and biogas production potential of pomegranate pomace before and after antioxidant and oil extraction. The quality changes of liquid extracts from pomegranate peel before and after thermal treatment during sterilization and storage were also determined.
Main findings:
- The antioxidants extracted from the pomegranates peel had higher yield and content than those from the seeds.
- Water extraction, which has the economic and safety merits, can be used as an environmentally friendly method for producing phenolics, proanthocyanidins and flavonoids from the pomegranates peel.
- The yield and content of antioxidants increased with reduced particle size and increased water/sample ratio and temperature, but antioxidant activity was low when extraction temperature was too high.
- The aqueous extracts prepared from pomegranate peel can be used as a stable nutraceuticals or food additives with a reasonable shelf life.
- Compared with conventional extraction and continuous ultrasound-assisted extraction, pulsed ultrasound-assisted extraction was a superior technology for producing antioxidants from peel of pomegranate marc.
- It is a valuable approach to extract oil and antioxidants followed by anerobic digestion of the residuals to produce biogas.
Selected Publications:
Teh H.E., W.H. Yokoyama, J.B. German, T.H. McHugh, and Z. Pan. 2019. Hypocholesterolemic effects of expeller-pressed and solvent-extracted fruit seed oils and defatted pomegranate seed meals. Journal of Agricultural and Food Chemistry. 67:6150-6159. https://doi.org/10.1021/acs.jafc.8b07186.
Young, J.E., Z. Pan, H. Teh, V. Menon, B. Modereger, J.J. Pesek, M., Matyska, L. Dao, and G. Takeoka. 2017. Phenolic composition of pomegranate peel extracts using a liquid chromatography-mass spectrometry approach with silica hydride columns. Journal of Separation Science. 40:1449-1456. https://doi.org/10.1002/jssc.201601310.
Qu, W., Z. Pan, A. Breksa, and H. Ma. 2014. Thermal stability of antioxidative extracts from pomegranate peel. Journal of the Science for Food and Agriculture. 1005-1012.
Qu, W., A.P. Breksa III, Z. Pan, and H. Ma. 2012. Quantitative determination of major polyphenol constituents in pomegranate products. Food Chemistry. 132:1585-1591.
Qu, W., A.P. Breksa III, Z. Pan, H. Ma, and T.H. McHugh. 2012. Storage stability of sterilized liquid extracts from pomegranate peel. Journal of Food Science. 77(7):765-772.