Scientific journal

58 2019

Journal of Food and Nutrition Research
Summary No. 1 / 2019

Jurmanović, S. – Jug, M. – Safner, T. – Radić, K. – Domijan, A.-M. – Pedisić, S. – Šimić, S. – Jablan, J. – Vitali Čepo, D.
Utilization of olive pomace as a source of polyphenols: Optimization of microwave-assisted extraction and characterization of spray-dried extract
Journal of Food and Nutrition Research, 58, 2019, No. 1, s. 51-62

Dubravka Vitali Čepo, Department of Food Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kovačića 1, 10000 Zagreb, Croatia. E-mail: dvitali@pharma.hr

Received 27 June 2018; 1st revised 21 August 2018; accepted 28 August 2018; published online 27 January 2019

Summary: Olive pomace lags behind in significant amounts after production of olive oil. Although it contains various biologically active compounds, its potential as a valuable source of functional ingredients has not been fully utilized. The main reasons are shortages of existing extraction and drying methods that result in poor quality extracts, unsuitable for further testing and processing. In this study, optimal conditions for sustainable, fast and efficient microwave-assisted extraction of pomace phenols has been proposed. The proposed procedure is based on applying the power of 700 W for 10 min in a closed vessel system, using 20% ethanol as the extraction solvent. For ensuring satisfactory yields and powder characteristics during spray drying, hydroxypropyl-beta-cyclodextrin was used and inlet temperature was set to 130 °C with the aspirator set at 100 %. Dry extracts obtained under optimized conditions contained significantly higher amounts of hydroxytyrosol (1216 mg·kg-1) and showed improved antioxidant activity in beta-carotene model system (214.7 g·kg-1) and DNA-scisson model system (minimal inhibitory concentration was 52.9 mg·l-1) in comparison to conventionally obtained extracts. Presented results enable objective assessment of the advantages of microwave extraction in processing olive waste into a functional food ingredient.

Keywords: olive pomace; microwave-assisted extraction; spray drying; scan electron microscopy; antioxidant activity

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