Valorization of Olive Pomace: Extraction of Maslinic and Oleanolic by Using Closed Vessel Microwave Extraction System
2022
Biltekin, Süheyla İlgün | Göğüş, Fahrettin | Yanık, Derya Koçak
PURPOSE: Maslinic and oleanolic acids are some of the valuable bioactive compounds present in olive pomace. The aim of this study is to investigate the direct use of wet olive pomace (without drying) for the extraction of these acids by taking advantage of the microwave technique and to determine the effect of extraction parameters on yield and quality. METHODS: The effects of microwave power (150–300 Watt), extraction time (4–20 min), and solvent to solid ratio (2.5–10) on extraction efficiency were examined. The extract further separated into maslinic and oleanolic acid fractions. The antioxidant activity and the antimicrobial effect of both extract and acid fractions were determined. RESULTS: Optimum conditions which provide the highest yield were found as 250 Watt, 12 min, and 10:1 for microwave power, time, and solvent to solid ratio, respectively. The total amount of maslinic and oleanolic acid obtained under optimum conditions was 26 ± 1.27 mg/g dry matter corresponding to 98.21% of the extract. The percentages of triterpenic acids present in the extract were 80% maslinic acid and 20% oleanolic acid. According to the DPPH (% inhibition 22.9 ± 0.8) and FRAP (263.1 ± 3.9 μM TE) results the maslinic acid fraction has shown the highest antioxidant activity. In addition, it was observed that the maslinic acid fraction had almost as much antimicrobial effect on the microorganisms as amoxicillin. CONCLUSION: Microwave-assisted extraction could be an efficient way for the extraction of maslinic and oleanolic acids from wet olive pomace with minimal processing and high yield.
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