A comparative analysis of polyphenols and fatty acids contents in methanol and acetone extracts from walnut and pumpkin meals

Abstract

In the last years the utilization of natural waste for alternative uses gained a lot of interest. The aim of this paper was to analyze the total polyphenols and the fatty acids content of a walnut and a pumpkin meal using two extraction methods. Bioactive compounds were extracted in acetone and methanol for 24 hours. The total phenolic content, antioxidant activity and fatty acids composition was determined in extracts by Folin–Ciocalteu , DPPH assay and gas chromatography. The acetone extracts have higher total polyphenol content and antioxidant capacity. Methanol extraction allowed the extraction of only 39% of the total polyphenols obtained in the acetone extracts. The antioxidant capacity was highly correlated with the total polyphenol contents irrespective of the type of the solvent or of meal. Only palmitic, stearic, oleic and linoleic fatty acids were extracted in acetone, where lauric, miristic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic acids were found in methanol extracts for both walnuts and pumpkin meals. In conclusion, walnut extracts have a higher content in total polyphenols, fatty acids and have a higher antioxidant activity than pumpkin extracts, in both solvents.