| Abstract [eng] |
White mulberry leaves (Morus alba) have been used for many years as a food source for silkworm caterpillars, but now they are increasingly used in the food industry, pharmacy. According to scientific articles, white mulberry leaves contain useful bioactive compounds that have a positive effect on human body. The leaves of this plant also have antioxidant properties. One of the oxidation sensitive products is hemp oil, so this final project is looking for ways to extend the shelf life of the oil and to slow down oxidative processes. Seventeen different extracts were used for the studies. They were extracted using accelerated solvent extraction (ASE) and supercritical extraction with carbon dioxide (SKE-CO2). The highest yields of ETPS extracts were obtained by extraction with ethanol and the lowest yields were found in hexane and acetone extracts. SKE-CO2 extraction gave a higher yield at a pressure of 30 MPa. The highest antiradical and antioxidant activity by DPPH, ABTS and ORAC methods was observed in the methanol extract when the raw material was used after SKE-CO2 extraction at a pressure of 30 MPa. The biggest amount of phenolic compounds was detected in ethanol extract prepared by ETPS extraction method. Chemical composition of white mulberry leaf extracts was determined by liquid chromatography with mass spectrometry. Dominant bioactive compounds in the extracts: 1. kaempferol derivatives: kaempferol rutinoside hexoside, kaempferol malonylhexoside, kaempferol hexoside (astragalin), kaempferol acetylhexoside; 2. quercetin derivatives: quercetin hexoside, quercetin acetylhexoside, quercetin hexoside hexoside, quercetin malonylhexoside; 3. caffeic acid derivatives: (3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, 4-O-caffeoylquinic acid); 4. others: eriodicitol, ferulic acid, salicylic acid. The content of triglyceride in hemp oil was also assessed using liquid chromatography system. This oil is dominated by 1-linoleoyl-2-linoleoyl-3-linolenoylglycerol (LLLn) and 1,2,3-trilinoleoylglycerol (LLL). The oxidative stability study of hemp oil without additives and with white mulberry leaf extracts was performed by the oxipres method. The induction period was similar for all extracts tested. However, a slightly slower oxidative degradation was observed in hemp oil with SKE-CO2 30 MPa extract. The antioxidant activity of hemp oil without additives and with different extracts of Morus alba was evaluated by the weight gain method. After three months, the results of the study were quite similar, but acetone extract after ETPS extraction was the most active and increased the stability of hemp oil by 7 days compared to the control. |
