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Evaluation of polyphenol content and lipoxygenase activity in selected oil cakes in terms of their valorization
* 1 , 2 , 2 , 3
1  Warsaw University of Life Sciences, Institute of Food Sciences, Department of Chemistry
2  Student Scientific Club of Biotechnologists—KNBiotech, Warsaw University of Life Sciences, 159 Nowoursynowska Str., 02-776 Warsaw, Poland
3  Oleovital Company, 32-020 Grajów, Poland
Academic Editor: Sonia Medina


Press cakes are pomace that is a by-product of pressing oil from oilseeds. Due to the high content of the lipid fraction, protein, carbohydrates and minerals, press cakes are used, among others, in the production of animal feed, and in recent years there is talk about the use of oil cakes/meals in human nutrition. Press cake can also be a good component of microbiological media. The aim of this study was the assessment of selected press cakes (linseed, rapeseed, hemp, safflower and camelina) in the context of their potential use as a lipid source in the biosynthesis of green note aroma compounds with the use of Yarrowia lipolytica yeast. For this purpose, the lipid fraction of press cakes was analyzed for unsaturated fatty acids and the activity of lipoxygenase - a key enzyme in the synthesis of green note aroma compounds. Due to the fact that lipoxygenase activity significantly depends on the acidity of the extraction medium and the presence of phenolic compounds, buffers with different pH (from 2 to 9) were used in the analysis and the content of polyphenols in individual extracts was determined.

Chromatographic analysis (GC) of the lipid fraction showed that the hemp and safflower cakes had the highest content of polyunsaturated fatty acids. PUFAs accounted for 68% and 73% of the total lipid fraction, respectively. Hemp cake extracts were also characterized by the highest lipoxygenase activity, at the level of approx. 76.4 ± 1.2 U/ml, with the lowest content of phenolic compounds (1.2 mg of chlorogenic acid/ml of the extract). It has been shown that it is worth undertaking optimization studies on the valorization of selected press cakes aimed at the use of the lipid fraction and oxidative activity of press cakes, which in combination with the activity of microorganisms can give promising results in the biosynthesis of green note aroma compounds.

Keywords: press cakes; valorization of waste; lipoxygenase; green note aroma compounds;