Júlia Ribeiro Sarkis

Pecan nuts are known for having high‐phenolic content and antioxidant capacity. In the present work, exhaustive extraction and LC–MS analysis of the soluble (SP) and insoluble‐bound phenolics (IBP) from pecan nut cake were performed. Its SP fraction (1.72 mg/g) is composed of ellagic acid, its glycosylated derivatives and gallic acid. The IBP fraction (2.20 mg/g) includes hydrolysable tannins derived from ellagic and gallic acids and proanthocyanidins from (epi)catechin and (epi)gallocatechin monomers; comprising 56% of the total phenolic content in pecan. Ellagic acid is the main phenolic found in both extracts corresponding to 1.96 mg/g of pecan nut cake. In addition, the extraction of the main SP found in pecan nut cake (ellagic acid and its derivatives) was optimized. The optimal conditions for SP extraction (40% ethanol, 85°C, and 60 ml/g) were able to extract 77% of the total ellagic acid found in pecan nut cake. In addition, the optimized condition for SP extraction (without the heated acid and methanol applied in IBP extraction) released a substantial quantity of ellagic acid and its glycosylated derivatives that are likely noncovalently absorbed in the pecan matrix. Therefore, the extraction process proposed in the present work shows considerably high efficiency using aqueous ethanol and high temperatures for the obtention of phenolics, particularly of ellagic acid, from pecan nut cake.

The objective of this work was to extract water‐soluble compounds from different seed and nut cakes under the same conditions and compare the phenolic content and antioxidant activity of the cake extracts. Seed cakes of sunflower, pumpkin, flaxseed and defatted sesame, and nut cakes of almond, pecan, macadamia and hazelnut were used in the experiments. Extracts were obtained by solid–liquid extraction with a water/ethanol solution (20:80, v/v). Total phenolic content, flavonoids, flavan‐3‐ols and condensed tannins in the extracts were determined using spectrophotometric analysis. Antioxidant properties of the extracts were determined by the DPPH and ABTS radical scavenging methods, and by determination of the reducing power and chelating activity. The extract from pecan nut cake presented the highest amounts of all compounds analyzed, followed by sunflower seed and hazelnut cake extracts. These samples also had the highest effects on the ABTS and DPPH radicals, as well as the uppermost reducing powers. The extracts from pecan nut and sunflower and sesame seeds were analyzed using HPLC and individual phenolics were further characterized.