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Phenolic antioxidants extraction from hazelnut shells

Bo Yuan, University of Nebraska - Lincoln


Hazelnut shells are rich in potentially health-promoting phenolic antioxidants. Various novel extraction techniques, which are considered as efficient alternatives to conventional extraction methods, have been developed for the extraction of nutraceuticals from different feedstocks. However, limited research has been conducted on novel techniques for the highly effective extraction of phenolic antioxidants from hazelnut shells. From a commercial point of view, conducting research to extract phenolic compounds from hazelnut shells efficiently in terms of high extraction rate and yield, using newly developed techniques, is important and timely. Therefore, the goal of this project was to develop and optimize novel extraction methods for the production of phenolic antioxidants from hazelnut shells. In this dissertation, effects of different extraction techniques, including conventional shaking bath extraction (SBE), and novel ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and high pressure/temperature extraction (HPTE), and their extraction conditions on total phenolic content and antioxidant capacities in the extracts were investigated and compared. Phenolic composition of the extracts under different extraction processes were analyzed. The total phenolic content and antioxidant capacities of the phenolic extracts under the optimal conditions from Nebraska hybrid hazelnut shells also were evaluated and compared. Results showed that hazelnut shells were rich in phenolic compounds with high antioxidant capacity. MAE could recover almost double the amount of total phenolics compared with SBE and UAE under their individual optimal extraction conditions, meanwhile, spending much shorter extraction time. Of these extraction methods, HPTE could recover the highest amount of phenolic compounds from hazelnut shells. Under the optimal HPTE conditions, the total phenolic content in the extracts was about 1.5 times higher than that of MAE, while the extraction time of HPTE was much longer than that of MAE and UAE using probe-type sonication, and the extraction temperature of HPTE was much higher than any other method. Among the tested Nebraska hybrid hazelnuts, cultivar 6-2 had the highest total phenolic content and antioxidant capacity.

Subject Area

Food Science|Chemical engineering

Recommended Citation

Yuan, Bo, "Phenolic antioxidants extraction from hazelnut shells" (2016). ETD collection for University of Nebraska-Lincoln. AAI10097962.