HPLC-MSn identification and quantification of phenolic compounds in hazelnut kernels, oil and bagasse pellets

- Differences among major phenolic groups in hazelnut kernels, pellets and oils
- Glansreginin A and glansreginin B detected for the first time in hazelnuts
- Total phenolic content decreases in the following order: kernels > pellets > oils.
- The prevalent phenolic subclass in hazelnut products comprised of flavan 3-ols.

The paper reports the phenolic content of kernels, bagasse pellets (residue of oil pressing) and oils from five different cultivars and a mix of cultivars. Phenolic compounds were identified by high-performance liquid chromatography coupled with mass spectrometry. Two compounds, glansreginin A and glansreginin B, were detected for the first time in hazelnuts. The main polyphenolic subclass comprised of mono- and oligomeric flavan 3-ols, which accounted between 34.2 and 58.3% in hazelnut kernels and between 36.7 and 48.6% in pellets of the total phenolics detected. In hazelnut oils four compounds have been detected, their content levels ranged from 0.97 to 0.01 μg g− 1. Total phenolic content ranged from 491.2 to 1700.4 mg GAE kg− 1 in kernels, from 848.4 to 1148.5 mg GAE kg− 1 in pellets and only from 0.14 to 0.25 mg GAE g− 1 in oils. The percentage of radical scavenging activity ranged from 60.0 to 96.4% for kernels, 63.0 to 73.2% for pellets and from 17.7 to 29.9% for oil. The study provides clear evidence on high phenolic contents and similarly high antioxidant potential of hazelnut kernels and bagasse pellets. The latter could be used as ingredients in cooking and baking or even for production of plant-based pharmaceuticals.