|Pan, Zhongli - John|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2009
Publication Date: 12/1/2009
Citation: Qu, W., Pan, Z., Zhang, R., Ma, H., Chen, X., Zhu, B., Wang, Z., Atungulu, G.G. 2009. Integrated extraction and anaerobic digestion process for recovery of nutraceuticals and biogas from pomegranate marcs. Transactions of the ASABE. 52(6):1997-2006. Interpretive Summary: This research developed an integrated process of antioxidant extraction followed by anaerobic digestion, which can be used to produce high functional antioxidants and high quality biogas and oil from the pomegranate marc. This process provides value-added utilizations of the by-product.
Technical Abstract: Pomegranate marc (PM), a by-product from pomegranate juice processing, has not been effectively utilized. The objectives of this study were to (1) determine the yields and properties of antioxidants (henceforth referring to total phenolics in terms of tannic acid equivalent) and oil extracted from various dry and wet constituents of PM, including peels, seeds and mixture and (2) evaluate the anaerobic digestibility and biogas production potential of PM before and after antioxidant extraction (AE) and oil extraction (OE). Water and petroleum ether were used as solvents in the extraction of antioxidants and oil respectively. The anaerobic digestion tests were conducted at 35 ± 2 °C with feedstock to microorganism ratio of 0.5 on volatile solid (VS) basis under two initial organic loadings of 3.0 and 5.0 gVS L"1. According to the results, both dry and wet PM extracts had similar extraction efficiency and functionality. The wet PM extract had antioxidant content of 23.0% which corresponded to antioxidant yield of 106 kg per ton of PM peel on dry basis (d.b. The DPPH scavenging activities of antioxidants were 6.5-6.6 g g"1 (d.b.). The oil yield from the dry PM seeds was 138 kg ton"1 (d.b.). Compared to the low initial organic loading, the high initial organic loading improved methane contents (55.1-67.5%), but not biogas yield. The extracted residuals of peel, seeds and mixture had methane yields of 148, 183 and 161 mL gVS"1, respectively, which were lower than that from the raw PM. Because the integrated process of extraction followed by anaerobic digestion can produce high functional antioxidants and high quality biogas and oil from the PM, it is recommended as a value-added utilization method for the by¬product.