Effect of Enzymatic Hydrolysis on the Antioxidant Properties of Alcoholic Extracts of Oilseed Cakes

Anna Ratz- Łyko^1*, Jacek Arct¹, Katarzyna Pytkowska¹, Sławomir Majewski^1,2 and Mateusz Bregisz<sup>3

1</sup>Department of Cosmetology, Academy of Cosmetics and Health Care, Podwale 13, PL-00-252 Warsaw, Poland
²Department of Dermatology and Venereology, Medical University of Warsaw, Koszykowa 82 A, PL-02-008 Warsaw, Poland
³Warsaw University of Technology, Faculty of Biotechnology, Noakowskiego 3, PL-00-664 Warsaw, Poland

Article history:
Received November 8, 2012
Accepted September 27, 2013

Key words:
Oenothera biennis, Borago officinalis, Nigella sativa, oilseed cake, polyphenols, enzymatic hydrolysis

Summary:
The aim of the present study is to compare changes in the total phenolic, flavonoid and reducing sugar content and antioxidant activity of alcoholic extracts of Oenothera biennis, Borago officinalis and Nigella sativa oilseed cakes before and after enzymatic hydrolysis. Extraction with ethanol and hydrolysis with different commercially available glycosidases: α-amylase, β-glucosidase, β-glucanase and their combinations in a ratio of 1:1:1 were investigated. Total phenolic, flavonoid and reducing sugar content, iron-chelating activity and antioxidant activity according to DPPH and ABTS tests were measured in non-hydrolysed extracts and compared with the results obtained for the extracts after the application of immobilised enzymes. As a result, the hydrolysed extracts had a higher phenolic and reducing sugar content as well as higher iron-chelating and antioxidant activities. Total phenolic content of Oenothera biennis, Borago officinalis and Nigella sativa oilseed cake extracts after enzymatic hydrolysis was higher in comparison with non-hydrolysed extracts, i.e. 2 times (for the enzyme combination), and 1.5 and 2 times (for ß-glucanase) (p<0.05), respectively. The best results in increasing the flavonoid and sugar content as well as in iron-chelating activity were obtained after enzymatic hydrolysis of oilseed cake extracts by ß-glucanase. Oilseed cake extracts after hydrolysis with an enzyme combination in a ratio of 1:1:1 had the highest increase in antioxidant activity.

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